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1
Fransen, J. A. M., K. V. Kardong, and P. Dullemeijer. "Feeding Mechanism in the Rattlesnake Crotalus durissus." Amphibia-Reptilia 7, no. 3 (1986): 271–302. http://dx.doi.org/10.1163/156853886x00055.
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AbstractCineradiography and electromyography were used to study the strike and swallowing behaviour of the rattlesnake, Crotalus durissus. From the data gathered, we describe the kinetic events of the cranial bones correlated with both the activity of individual jaw muscles (electromyograms) and with the calculated relative forces produced by these same muscles. During the strike, the independently suspended jaws of left and right sides simultaneously protract to erect the folded fangs. This is accompanied by opening of the lower jaws. Some low level activity first appears in the depressor muscles, but immediately thereafter they and all other jaw muscles suddenly and nearly simultaneously reach peak output. From the calculated relative muscle forces, vector models of the jaws were determined for early and peak points in the strike. Swallowing is accomplished by reciprocating alternate motions of bones on the left and right sides of the skull. This produces a swallowing cycle of two phases, moving and fixing. In turn, each phase divides into three parts-opening, advance, close. On the ipsilateral side, opening is characterized by a relaxation of contact of bones and teeth they bear with the prey and the braincase begins rotation about three axes simultaneously. Motions begun in opening, contiue into advance, but now the ipsilateral jaw elements are protracted to progress them along the prey. As protraction ends, the jaws again come into contact with the prey to establish the close part of the moving phase of swallowing. After a pause, the fixing phase begins while opposite jaw elements now take their turn to progress through similar displacements. During this fixing phase ipsilateral elements arc often further retracted. Emphasis is given to the complicated rotations of the braincase which contribute first to disengagement of teeth and second to advancement of suspended jaw elements around and along the prey. Most muscles reached peak output during one of the two swallowing phases, although the timing and intensity of these peaks varied between muscles. The relative muscle forces were used to construct vector models of the jaws during stages of swallowing. Upon these vector models and from the overall patterns of activity, determination was made of the likely roles played by individual muscles in abduction, protraction, and adduction of jaw elements. Muscles, besides being basic movers of the jaw elements, apparently also play critical parts in stabilizing and regulating the controlled positioning of bones.
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Wilga, C. D., and P. J. Motta. "Feeding mechanism of the atlantic guitarfish rhinobatos lentiginosus:modulation of kinematic and motor activity." Journal of Experimental Biology 201, no. 23 (December 1, 1998): 3167–83. http://dx.doi.org/10.1242/jeb.201.23.3167.
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The kinematics and muscle activity pattern of the head and jaws during feeding in the Atlantic guitarfish Rhinobatos lentiginosus are described and quantified using high-speed video and electromyography to test hypotheses regarding the conservation and modulation of the feeding mechanism. Prey is captured by the guitarfish using suction. Suction capture, bite manipulation and suction transport behaviors in the guitarfish are similar to one another in the relative sequence of kinematic and motor activity, but can be distinguished from one another by variation in absolute muscle activation time, in the presence or absence of muscle activity and in the duration of muscle activity. A novel compression transport behavior was observed that is strikingly different from the other feeding behaviors and has not been described previously in elasmobranchs. The mechanism of upper jaw protrusion in the guitarfish differs from that described in other elasmobranchs. Muscle function and motor pattern during feeding are similar in the plesiomorphic cranial muscles in the guitarfish and the spiny dogfish probably because of their shared ancestral morphology. Modulation in recruitment of jaw and hyoid depressor muscles among feeding behaviors in the guitarfish may be a consequence of duplication of muscles and decoupling of the jaws and hyoid apparatus in batoids.
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Friel, J. P., and P. C. Wainwright. "Evolution of complexity in motor patterns and jaw musculature of tetraodontiform fishes." Journal of Experimental Biology 202, no. 7 (April 1, 1999): 867–80. http://dx.doi.org/10.1242/jeb.202.7.867.
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The prey-processing behavior and jaw-adducting musculature of tetraodontiform fishes provide a novel system for studying the evolution of muscles and their function. The history of this clade has involved a pattern of repeated ‘duplications’ of jaw muscles by physical subdivision of pre-existing muscles. As a result, the number of adductor mandibulae muscles in different taxa varies from as few as two to as many as eight. We used electromyography (EMG) to quantify motor-pattern variation of adductor mandibulae muscles in four tetraodontiform species during feeding events on prey items that varied in durability and elusiveness. Statistical analyses of variation in EMG variables revealed significant differences in motor patterns between duplicated muscles derived from a common ancestral muscle in seven of nine cases examined. Overall individual EMG timing variables (e.g. relative onset or duration of bursts) were slightly less likely to diverge functionally than amplitude variables (e.g. relative intensity of bursts). Functional divergence was found in significant overall differences between muscles and twice as frequently in significant muscle-by-prey interaction terms. Such interactions represent an underappreciated way in which motor patterns can evolve and diversify. Regional variation was documented in undivided muscles in two species, indicating that it is possible for functional subdivision to precede anatomical subdivision. This study shows that phylogenetic increases in the number of tetraodontiform jaw adductor muscles have been associated with increases in the functional complexity of the jaws at the level of muscle activation patterns.
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Previatto, DM, and SR Posso. "Jaw musculature of Cyclarhis gujanensis (Aves: Vireonidae)." Brazilian Journal of Biology 75, no. 3 (September 25, 2015): 655–61. http://dx.doi.org/10.1590/1519-6984.20113.
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AbstractCyclarhis gujanensis is a little bird which feeds on high number of large preys, such frogs, lizards, snakes, bats and birds. As there are few studies on the cranial anatomy of this species, we aimed to describe the cranial myology to contribute to the anatomical knowledge of this species and to make some assumptions about functional anatomy. Thus, we described the muscles from the jaw apparatus (external and internal adductor muscles, the muscles of the pterygoid system and the depressor muscles of the mandible). The adductor system is the greatest and multipinulated, particularly in its origin in the caudal portion of the temporal fossa. The depressor jaw muscles systems are enlarged with many components in complexity. The most of jaw apparatus muscles are short, but the strength (biting or crushing forces) from short feeding apparatus fibers probably is increased by high number of components and pinnulation. These anatomical aspects of the muscles indicate a considerable force in the jaws, without which C. gujanensis probably could not cut their prey into smaller pieces. However, functional approaches to analysis of forces of the muscle fibers are needed to corroborate / refute the hypotheses mentioned above.
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Patil, Santosh R., G. Maragathavalli, and DNSV Ramesh. "Bite Force: A Contemporary Narrative Review." International Journal of Health Sciences and Research 12, no. 5 (May 10, 2022): 108–16. http://dx.doi.org/10.52403/ijhsr.20220514.
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Bite force is one of the indicators of the masticatory apparatus's functioning status, as determined by the activation of the jaw's elevator muscles as a result of craniomandibular biomechanics. Bite force is used to investigate the activity related to the dentition, occlusal factor, dentures and implant therapy, temporomandibular diseases, orthognathic surgery, and neuromuscular modifications. Masticatory functions are determined by muscular forces and the total number of functioning teeth. The goal of calculating maximal biting force is to assess the force generated by the mandible's elevator muscles. The biting force is generated by the action of muscles in the maxilla and mandible, which is then disseminated to the thing being chewed via the teeth. The forces which result essentially while during chewing activity performance on the jaw bones in varying dimensions which depends on activity of musculature that cause an unambiguous action. Key words: Bite force, muscles, teeth, jaws, factors.
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Hollowell, D. E., and P. M. Suratt. "Mandible position and activation of submental and masseter muscles during sleep." Journal of Applied Physiology 71, no. 6 (December 1, 1991): 2267–73. http://dx.doi.org/10.1152/jappl.1991.71.6.2267.
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Movement of the mandible could influence pharyngeal airway caliber because the mandible is attached to the tongue and to muscles that insert on the hyoid bone. In normal subjects and patients with obstructive sleep apnea (OSA) we measured jaw position during sleep with strain gauges, as well as masseter and submental electromyograms, airflow, esophageal pressure, oximetry, electroencephalograms, and electrooculograms. Jaws of patients with OSA were open more than those of normal subjects at end expiration and opened further at end inspiration, particularly at the termination of apneas when the masseter and submental muscles contracted. Masseter activation occurred only in patients with OSA and in a pattern similar to that of submental muscles. Jaw opening at end expiration could narrow the upper airway, whereas opening at end inspiration could reflect efforts to expand the airway with tracheal tug and with submental muscle activation and efforts to open the mouth to allow mouth breathing. Masseter contraction does not close the jaw but may serve to stabilize it.
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Gn, Suma, and Adrita Nag. "Management of Oromandibular Dystonia: A Case Report and Literature Update." Case Reports in Dentistry 2017 (2017): 1–7. http://dx.doi.org/10.1155/2017/3514393.
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Oromandibular dystonia (OMD) is a movement disorder characterized by involuntary, paroxysmal, and patterned muscle contractions of varying severity resulting in sustained spasms of masticatory muscles, affecting the jaws, tongue, face, and pharynx. It is most commonly idiopathic or medication-induced, but peripheral trauma sometimes precedes the condition. We present a case report of a 26-year-old female patient who suffered repetitive bouts of hemifacial muscle contractions for 2 years on closing the mouth which interfered in patient’s well-being and quality of life by hampering her ability to eat and talk and to the extent of inability to breath due to contractions of her neck muscles. Prompt diagnosis of a chronic oromandibular dystonia jaw closing type led to the control of the spasmodic muscle contractions within 24 hours and alleviation of patients fear of morbidity.
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Greaves, Walter Stalker. "Modeling the distance between the molar tooth rows in mammals." Canadian Journal of Zoology 80, no. 2 (February 1, 2002): 388–93. http://dx.doi.org/10.1139/z02-008.
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The sum of all possible bite forces along a mammalian tooth row is related to the area under the curve when bite force is plotted from one end of the tooth row to the other. Integrating the equation of this plot and dividing by the length of the entire jaw, from joint to incisor, gives the average bite force along the entire jaw (as opposed to along the tooth row). Calculations indicate that for any jaw shape there is only one location for the tooth row relative to the midline of the skull, where the average bite force is maximized; the average force is lower when the tooth row is closer to, or farther from, the midline. In addition, for animals with long narrow jaws, the location where this maximum is realized is relatively closer to the midline than it is for animals with short wide jaws. In many mammals, the distance between the jaw joints (jaw width) often varies between 60 and 80% of the distance from the jaw joints to the incisor (jaw length) in narrow and wide jaws, respectively. Length is measured perpendicular to the resultant force of the jaw muscles. Accepting that average bite force will be maximized, the model predicts that in the longer, narrower jaws the distance between the two molar rows will be approximately half the width of the jaw (and will approach 60% in the shorter, wider jaws).
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Wainwright, P. C., and R. G. Turingan. "COUPLED VERSUS UNCOUPLED FUNCTIONAL SYSTEMS: MOTOR PLASTICITY IN THE QUEEN TRIGGERFISH BALISTES VETULA." Journal of Experimental Biology 180, no. 1 (July 1, 1993): 209–27. http://dx.doi.org/10.1242/jeb.180.1.209.
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Teleost fishes typically capture prey with the oral jaws and perform most types of prey- processing behavior with the pharyngeal jaw apparatus. In these fishes, the motor patterns associated with the different stages of feeding are quite distinct, and fish can modify muscle activity patterns when feeding on different prey. We examined motor pattern variation in the queen triggerfish, Balistes vetula, a versatile predator that both captures and processes prey with its oral jaws. During feeding on three prey that differed in hardness and elusiveness, three distinct patterns of behavior could be identified on the basis of patterns of muscle activity: prey capture, buccal manipulation and blowing. During prey capture by suction feeding, the retractor arcus palatini muscle (RAP) commenced activity before the levator operculi muscle (LOP). In both buccal manipulation and blowing, the RAP began activity well after the onset of activity in the LOP. Both prey capture and buccal manipulation motor patterns varied when fish fed on different prey. When capturing hard-shelled and non-elusive prey, B. vetula did not employ suction feeding but, instead, the fish directly bit parts of its prey. The motor pattern exhibited during direct biting to capture prey was different from that during suction feeding, but was indistinguishable from the pattern seen during the repeated cycles of buccal manipulation. Harder prey elicited significantly longer bursts of activity in the jaw adductor muscles than did soft prey. In spite of the involvement of the oral jaws in virtually all stages of feeding, B. vetula shows levels of variation between patterns of behavior and types of prey characteristic of previously studied teleost fishes. Thus, the coupling of capture and processing behavior patterns in the repertoire of the oral jaws does not appear to constrain the behavioral versatility of this species.
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Huby, Alessia, Aurélien Lowie, Anthony Herrel, Régis Vigouroux, Bruno Frédérich, Xavier Raick, Gregório Kurchevski, Alexandre Lima Godinho, and Eric Parmentier. "Functional diversity in biters: the evolutionary morphology of the oral jaw system in pacus, piranhas and relatives (Teleostei: Serrasalmidae)." Biological Journal of the Linnean Society 127, no. 4 (May 8, 2019): 722–41. http://dx.doi.org/10.1093/biolinnean/blz048.
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Abstract Serrasalmid fishes form a highly specialized group of biters that show a large trophic diversity, ranging from pacus able to crush seeds to piranhas capable of cutting flesh. Their oral jaw system has been hypothesized to be forceful, but variation in bite performance and morphology with respect to diet has not previously been investigated. We tested whether herbivorous species have higher bite forces, larger jaw muscles and more robust jaws than carnivorous species. We measured in vivo and theoretical bite forces in 27 serrasalmid species. We compared the size of the adductor mandibulae muscle, the jaw mechanical advantages, the type of jaw occlusion, and the size and shape of the lower jaw. We also examined the association between bite performance and functional morphological traits of the oral jaw system. Contrary to our predictions, carnivorous piranhas deliver stronger bites than their herbivorous counterparts. The size of the adductor mandibulae muscle varies with bite force and muscles are larger in carnivorous species. Our study highlights an underestimated level of functional morphological diversity in a fish group of exclusive biters. We provide evidence that the trophic specialization towards carnivory in piranhas results from changes in the configuration of the adductor mandibulae muscle and the lower jaw shape, which have major effects on bite performance and bite strategy.
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Nguyen, Allyn, Jordan P. Balaban, Emanuel Azizi, Robert J. Talmadge, and A. Kristopher Lappin. "Fatigue resistant jaw muscles facilitate long-lasting courtship behaviour in the southern alligator lizard ( Elgaria multicarinata )." Proceedings of the Royal Society B: Biological Sciences 287, no. 1935 (September 23, 2020): 20201578. http://dx.doi.org/10.1098/rspb.2020.1578.
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The southern alligator lizard ( Elgaria multicarinata ) exhibits a courtship behaviour during which the male firmly grips the female's head in his jaws for many hours at a time. This extreme behaviour counters the conventional wisdom that reptilian muscle is incapable of powering high-endurance behaviours. We conducted in situ experiments in which the jaw-adductor muscles of lizards were stimulated directly while bite force was measured simultaneously. Fatigue tests were performed by stimulating the muscles with a series of tetanic trains. Our results show that a substantial sustained force gradually develops during the fatigue test. This sustained force persists after peak tetanic forces have declined to a fraction of their initial magnitude. The observed sustained force during in situ fatigue tests is consistent with the courtship behaviour of these lizards and probably reflects physiological specialization. The results of molecular analysis reveal that the jaw muscles contain masticatory and tonic myosin fibres. We propose that the presence of tonic fibres may explain the unusual sustained force properties during mate-holding behaviour. The characterization of muscle properties that facilitate extreme performance during specialized behaviours may reveal general mechanisms of muscle function, especially when done in light of convergently evolved systems exhibiting similar performance characteristics.
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Smaglyuk, Lyubov V., and Anastasiia V. Liakhovska. "EMG-CHARACTERISTIC OF MASTICATORY MUSCLES IN PATIENTS WITH CLASS II MALOCCLUSION AND TEMPOROMANDIBULAR DISORDERS." Wiadomości Lekarskie 72, no. 5 (2019): 1043–47. http://dx.doi.org/10.36740/wlek201905217.
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Introduction: A stable state of musculoskeletal system is provided by harmony of occlusion, the anatomy of temporomandibular joints, and the activity of the masticatory muscles under the control of peripheral and central nervous system. Surface electromyography (EMG) is a well-used modality and is used in dentistry to access the status of the muscles of mastication. The aim of the research was to evaluate the EMG-characteristic of masticatory muscles in patients with TMD and Angle Class II malocclusion. Materials and methods: The study comprised 23 patients with Angle Class II malocclusion and TMD. The average age of the subjects was 26,5 ± 2,3 years. Malocclusion was evaluated according to Angle classification, TMD – according to the Research Diagnostic Criteria (RDC/TMD). Registration of EMG-activity of masseter and anterior temporalis muscles was performed during maximum voluntary clenching, clenching on the right and left sides. Results: EMG-activity of masticatory muscles are characterized by: 1) increased values of EMG-activity of temporal and masseter muscles – peak and average amplitude in tests of unilateral clenching and maximum clenching (values are greater than 2000 μV); 2) in unilateral clenching of jaws (on the left or right) the increased EMG-activity was detected on the balancing side; 3) in unilateral clenching of jaws (on the left or right) the increased muscle activity on the working side with disproportional (asymmetric) load distribution between masseter and temporal muscles has been found. Conclusions: Patients with Angle Class II malocclusion and TMD were found features of EMG-activity of masticatory muscles.
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Wilga, C. D., and P. J. Motta. "Durophagy in sharks: feeding mechanics of the hammerhead Sphyrna tiburo." Journal of Experimental Biology 203, no. 18 (September 15, 2000): 2781–96. http://dx.doi.org/10.1242/jeb.203.18.2781.
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This study investigates the motor pattern and head movements during feeding of a durophagus shark, the bonnethead Sphyrna tiburo, using electromyography and simultaneous high-speed video. Sphyrna tiburo feeds almost exclusively on hard-shelled crabs, with shrimp and fish taken occasionally. It captures crabs by ram feeding, then processes or reduces the prey by crushing it between molariform teeth, finally transporting the prey by suction for swallowing. The prey-crushing mechanism is distinct from that of ram or bite capture and suction transport. This crushing mechanism is accomplished by altering the duration of jaw adductor muscle activity and modifying jaw kinematics by the addition of a second jaw-closing phase. In crushing events, motor activity of the jaw adductor muscles continues (biting of the prey occurs as the jaws close and continues after the jaws have closed) throughout a second jaw-closing phase, unlike capture and transport events during which motor activity (biting) ceases at jaw closure. Sphyrna tiburo is able to take advantage of a resource (hard prey) that is not readily available to most sharks by utilizing a suite of durophagous characteristics: molariform teeth, a modified jaw protrusor muscle, altered jaw adductor activity and modified jaw kinematics. Sphyrna tiburo is a specialist feeder on crab prey as demonstrated by the lack of differences in kinematic or motor patterns when offered prey of differing hardness and its apparent lack of ability to modulate its behavior when feeding on other prey. Functional patterns are altered and coupled with modifications in dental and jaw morphology to produce diverse crushing behaviors in elasmobranchs.
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Sørensen, Martin V., Seth Tyler, Matthew D. Hooge, and Peter Funch. "Organization of pharyngeal hard parts and musculature in Gnathostomula armata (Gnathostomulida: Gnathostomulidae)." Canadian Journal of Zoology 81, no. 9 (September 1, 2003): 1463–70. http://dx.doi.org/10.1139/z03-135.
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The pharynx of Gnathostomula armata, like that of other members of the phylum Gnathostomulida, consists of a set of jaws, a basal plate, and a muscular bulb that encloses these cuticularized hard parts. Field-emission scanning electron microscopy (SEM) provides additional information about the hard parts and shows that the dentition of the jaws is arranged in three rows: 710 teeth in a dorsal row, 1620 teeth in a medial row, and 20 teeth in a ventral row, a pattern different from that reported from light microscopy (LM). SEM also shows that the dentition of the basal plate is more like that of other Gnathostomula species than was previously discerned. Confocal laser scanning microscopy shows the musculature of the pharyngeal bulb to comprise diductors that open and tilt the jaws, looplike abductors that retract them as they snap shut by recoil, and a pair of inclinators and pair of levators that also participate in tilting the jaws back and forth. A constrictor running ventral to and behind the jaws may work to protrude them. Two arc-shaped muscles attached to the basal plate pull it forward and tilt it down to scrape food from the substratum so that it can be grabbed by the jaws. Paired retractor muscles pull the basal plate back into the mouth.
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Negrea, Doina, Andrea Deaconescu, and Tudor Deaconescu. "Actuation by Pneumatic Muscles of a Parallel Asymmetric Gripper System." Applied Mechanics and Materials 548-549 (April 2014): 943–47. http://dx.doi.org/10.4028/www.scientific.net/amm.548-549.943.
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Deployment of pneumatic muscles for the actuation of gripper systems is a solution with numerous benefits, related mostly to the developed force, structural rigidity, compliance and dexterity. The paper discusses a gripper variant with parallel jaws, actuated by a pneumatic muscle. The structure of the mechanism is presented, and the transmission functions of speeds and forces are determined. Due to its construction, the gripper system can be used for precision applications, similar to natural systems.
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Negrea, Doina, Tudor Deaconescu, and Andrea Deaconescu. "Symmetrical Pneumatic Muscle Actuated Gripper System with Two Mobile Jaws." Applied Mechanics and Materials 541-542 (March 2014): 852–56. http://dx.doi.org/10.4028/www.scientific.net/amm.541-542.852.
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The paper argues the possibility of utilising artificial muscles actuated with compressed air in the construction of industrial gripper systems. Their utilisation as motors comes as a response to the increasingly sophisticated requirements these have to satisfy, related to the developed force, structural rigidity, compliance and dexterity. The paper presents a variant of symmetrical gripper system with two mobile jaws actuated by a pneumatic muscle. The main requirements for this gripper are defined, the structure of the mechanism is presented and the transmission functions of forces and velocities are determined. Eventually the paper discusses the construction of the system and its functional limitations.
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Winkless, Laurie. "Give us a smile! Artificial muscles for robotic jaws." Materials Today 19, no. 4 (May 2016): 188. http://dx.doi.org/10.1016/j.mattod.2016.03.008.
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Woźniak, Krzysztof, Mariusz Lipski, Damian Lichota, and Liliana Szyszka-Sommerfeld. "Muscle Fatigue in the Temporal and Masseter Muscles in Patients with Temporomandibular Dysfunction." BioMed Research International 2015 (2015): 1–6. http://dx.doi.org/10.1155/2015/269734.
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The aim of this study is to evaluate muscle fatigue in the temporal and masseter muscles in patients with temporomandibular dysfunction (TMD). Two hundred volunteers aged 19.3 to 27.8 years (mean 21.50, SD 0.97) participated in this study. Electromyographical (EMG) recordings were performed using a DAB-Bluetooth Instrument (Zebris Medical GmbH, Germany). Muscle fatigue was evaluated on the basis of a maximum effort test. The test was performed during a 10-second maximum isometric contraction (MVC) of the jaws. An analysis of changes in the mean power frequency of the two pairs of temporal and masseter muscles (MPF%) revealed significant differences in the groups of patients with varying degrees of temporomandibular disorders according to Di (P<0.0000). The study showed an increase in the muscle fatigue of the temporal and masseter muscles correlated with the intensity of temporomandibular dysfunction symptoms in patients. The use of surface electromyography in assessing muscle fatigue is an excellent diagnostic tool for identifying patients with temporomandibular dysfunction.
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ELLERS, OLAF, and MALCOLM TELFORD. "Forces Generated by the Jaws of Clypeasteroids (Echinodermata: Echinoidea)." Journal of Experimental Biology 155, no. 1 (January 1, 1991): 585–603. http://dx.doi.org/10.1242/jeb.155.1.585.
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Aristotle' lantern acts like a five-toothed ‘vice grip.’ Contraction of the interpyramidal muscles creates tangential stresses that are converted to radial forces along the teeth. Two mechanical models are proposed to explain this conversion. In the first, the lantern is regarded as a thick-walled cylinder resisting internal pressure; in the second, it is treated as a cluster of wedges. The two models differ primarily in the allowance of radial forces within the muscle in the cylinder and their exclusion in the wedge model. Maximum muscle stress required for a given force along the teeth depends on the ratio of external to internal lantern radii (ro/ri). Maximal force requires that (ro/ri) should be greater than 2, which is the case in Clypeaster rosaceus (L.). The models allow calculation of a dimensionless number, F, which scales the force exerted by the teeth for changes in lantern size and the number of pyramids. Biting force was measured in C. rosaceus and used to calculate the muscle stress required by the mechanical models. For the thick-walled cylinder, maximum interpyramidal muscle stress was calculated to be 2.8×106N m−2. For the wedge model it was 1.9×105N m−2. The models were supported by comparison of predicted with observed biting forces in another clypeasteroid, Encope michelini L. Agassiz.
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Nikitin, Vladislav Nikolaevich, and Natalia Leonidovna Bushueva. "DISTRIBUTION OF THE EFFORTS OF THE MUSCLE MUSCLES HUMAN DENTAL SYSTEM AT ASYMMETRIC TONE SURFACE MASKING MUSCLES." SOFT MEASUREMENTS AND COMPUTING 1, no. 4 (2021): 19–24. http://dx.doi.org/10.36871/2618-9976.2021.04.003.
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The dentofacial system is closely related to the musculoskeletal, digestive, nervous, cardiovascular systems, etc. The functioning of the dentofacial system affects nutrition, breathing, swallowing, speech, hearing, etc., where occlusion is one of its main parameters. Many pathologies in the dentofacial system are also associated with a change in the efforts of the masticatory muscles, where hypertonicity of the superficial masticatory muscle is most common. The article considers an example of her hypertonicity by biomechanical modelling. For this, the problem of determining of the masticatory muscle efforts was solved at the maximum value of the force of compression of the jaws, which was 600 N. The cases were considered when the minimum possible value of the force of the superficial masticatory muscle was 70%, 80% and 90% of the maximum value. It was found that for the case while the minimum values of the efforts of all masticatory muscles do not exceed 50% of their maximum possible values, then the distribution of muscle efforts remains unchanged, i.e. the values of muscle efforts do not change. When at least one of the muscles exceeds its half of the maximum possible effort, it is observed that the efforts of the remaining muscles on the same side of the face decrease or remain approximately at the same level, and on the opposite side, the muscle efforts initially decrease, and at 80% and 90% of the maximum possible magnitude of the effort of the superficial chewing muscle increases again. In further works, various combinations of hypertonicity of the masticatory muscles, as well as the hypotonia of these muscles, are assumed.
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Okino, Akihisa, Hideaki Takanobu, Atsuo Takanishi, Kayoko Ohtsuki, Masatoshi Ohnishi, and Masayuki Yoshida. "A Clinical Jaw Movement Training Robot for Mouth Opening/Closing and Lateral Movement Training." Journal of Robotics and Mechatronics 16, no. 6 (December 20, 2004): 579–86. http://dx.doi.org/10.20965/jrm.2004.p0579.
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This paper discusses a jaw movement training robot implementing a 6-DOF (degrees of freedom) parallel mechanism, and its application to mouth opening and closing and lateral movement training. Temporomandibular joints (TMJ) syndrome prevents patients from opening their mouths or moving their jaws easily due to problems with mandibular joints, mastication muscles, and other organs involved in food chewing. Conventional therapy involves simple mouth opening apparatuses, although individual techniques vary with the physician. We developed and improved a jaw movement training robot that aids jaw opening and closing and lateral jaw movement training. This system consists of a 6-DOF slave manipulator representing a patient manipulator and a 2-DOF or 3-DOF master manipulator representing the doctor command manipulator.
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Kear, Amanda J. "Morphology and function of the mandibular muscles in some coleoid cephalopods." Journal of the Marine Biological Association of the United Kingdom 74, no. 4 (November 1994): 801–22. http://dx.doi.org/10.1017/s0025315400090068.
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The functional morphology of the buccal mass of 23 species of cephalopod (Octopoda, 4 species; Teuthoidea, 17; Sepioidea, 2) was investigated by gross dissection, histology and observations on fresh preparations. Cephalopod beaks lack a joint or articulation point. The jaws slide and rotate around an area rather than a fixed point. During closing the superior mandibular muscle (SMM) provides the force of a bite and the largest movement vector, whilst the inferior mandibular muscle (IMM) acts to retract the upper beak, causing shearing action. Dorsal portions of the lateral mandibular muscles (LMM) flex the upper beak walls outwards, probably to accommodate the backwards sweep of the radula and buccal palps during closing. To open the beaks, the ventral portions of the lateral mandibular muscles pull the rear lateral walls of the two beaks towards each other, moving the lower beak back relative to the upper.
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Decusară, Mioara, Cerasella Dorina Şincar, Magdalena Rusu, Alexandru Mircea Nicolau, Gabriel Valeriu Popa, and Laurenţiu Drăguş. "Orthodontic treatment for closing diastemas mandibular space to adult patient – clinical case." Romanian Journal of Stomatology 62, no. 1 (March 31, 2016): 43–47. http://dx.doi.org/10.37897/rjs.2016.1.9.
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Maxillary functions (chewing, swallowing, speech, phonation, breathing and gestures) are ensured by automatic and rhythmic movements of jaws, facial muscles, lips and tongue. Functional disorders can cause malocclusions or may contribute to worsening of malocclusions to other reasons.
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Zalavina, S. V., and Е. Yu Apraksina. "INFLUENCE OF INDUSTRIAL VIBRATION ON MINERAL METABOLISM, ORGANS OF THE ORAL CAVITY AND FETAL MYOCARDIUM." Sibirskij medicinskij vestnik, no. 1 (2021): 22–28. http://dx.doi.org/10.31549/2541-8289-2021-1-22-28.
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In the study, the morphometric analysis of bone trabeculae of the developing jaws, tooth buds, tongue muscles, masseter muscle, and myocardium of 20-day fetuses of Wistar rats, exposed to vibration from the 9th to the 18th day of prenatal ontogenesis, was performed. The concentration of Ca, Cd, Cu, Fe, Mg, P, Pb, Se, Zn was determined in the liver of pregnant females exposed to vibration. The morphometric study revealed an acceleration of the osteogenesis of jaws and dentinogenesis of tooth buds. In the myocardium and masseter muscle signs of interstitial edema and a decrease in the area of the vessels of the microvasculature are determined. In the liver, there is a decrease in the amount of Ca, Mg and Fe, which is accompanied by an increase in the content of Cd and Pb. The revealed shifts in mineral metabolism indicate gross impairment of chemicals' homeostasis in the mother-fetus system, which underlies the imperfect morphogenesis of the fetal dentition and will be the basis for the formation of pathology of orofacial organs and cardiovascular pathology in offspring.
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Pankratova, Nataliia, Mikhail Postnikov, Aziza Khasbolatova, Tatiana Repina, Anastasiia Rodionova, Elizaveta Postnikova, Maxim Kirilin, and Dmitry Domenyuk. "DEVIATIONSIN THE POSITION OFTHETHIRD MOLARS." Archiv Euromedica 10, no. 4 (December 17, 2020): 156–62. http://dx.doi.org/10.35630/2199-885x/2020/10/4.35.
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Timely teething is one of the most important indicators of the harmonious development of the dentoalveolar system, which is determined by the correct (physiological) position of the teeth in the dentition, ensuring the optimal shape and function of the temporomandibular joint, the work of the chewing muscles, the height of the lower part of the face, and aesthetics of a smile. Retention of individual teeth is often the reason for the formation of anomalies in the dentition, their closure, functional and aesthetic disorders. An urgent problem in modern dentistry is the problem associated with the development of third molars. According to the results of the analysis of 3000 orthopantomograms of the jaws of patients 7–25 years old with dentoalveolar anomalies, the spatial arrangement of the primordial of the third molars relative to the buttresses of the upper and lower jaws was studied. It was found that the buttresses on the upper jaw are vertical and do not interfere with the correct eruption of the third molars. The buttresses located near the primordial of the third molars on the lower jaw contribute to the retention of the third molars due to the change in inclination during the formation stage.
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Popov, N. M. "Prolonged contracture of the chewing muscles." Neurology Bulletin VII, no. 2 (November 25, 2020): 181–209. http://dx.doi.org/10.17816/nb51115.
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Among the numerous symptoms, which are expressed by the functional and organic lesions of the nervous system, contracture of the masticatory muscles, trismus, occupies far from the last place, arising under the influence of very different conditions. Most often, it develops on the basis of general neuroses and in such a case it differs for the most part in a transient character. Quite often, we can also observe the reflex origin of this contracture, especially with irritation of the sensitive nerves of the trigeminal nerve; known ex. cases when a minor dental operation in nervous subjects had as its result the reduction of the jaws, which lasted up to three months (observation of Travers'a).
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Gronenberg, W. "The trap-jaw mechanism in the dacetine ants Daceton armigerum and Strumigenys sp." Journal of Experimental Biology 199, no. 9 (September 1, 1996): 2021–33. http://dx.doi.org/10.1242/jeb.199.9.2021.
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Ants of three different subfamilies, among them the tribe Dacetini, have evolved very fast snapping mandibles called trap-jaws. The two dacetine genera examined, the large Daceton and the small Strumigenys, employ the same mechanism for their mandible strike. Video analysis reveals that, in Strumigenys sp., the strike takes less than 2.5 ms. It is released within 5 ms by contact of trigger hairs on the labrum. The ants employ a catapult mechanism to generate such a fast movement. Before the strike, the mandibles are opened wide and locked in the open position by the labrum, which functions as a latch. They stay open even when the large slow closer muscles contract. Upon trigger hair stimulation, the labrum is pulled backwards by a small, fast trigger muscle. The mandibles are thus freed from the catch and close rapidly. This reflex is controlled by giant sensory and motor neurones in the labral neuromere that are probably monosynaptically coupled. The short latency of the reflex thus results from the combination of a catapult mechanism, fast trigger muscles, high neuronal conduction velocities and small synaptic delays. Comparison with the trap-jaw mechanism of the ant genus Odontomachus reveals a remarkable example of convergent evolution.
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Hiiemae, Karen M., and Jeffrey B. Palmer. "Tongue Movements in Feeding and Speech." Critical Reviews in Oral Biology & Medicine 14, no. 6 (November 2003): 413–29. http://dx.doi.org/10.1177/154411130301400604.
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The position of the tongue relative to the upper and lower jaws is regulated in part by the position of the hyoid bone, which, with the anterior and posterior suprahyoid muscles, controls the angulation and length of the floor of the mouth on which the tongue body ‘rides’. The instantaneous shape of the tongue is controlled by the ‘extrinsic muscles’ acting in concert with the ‘intrinsic’ muscles. Recent anatomical research in non-human mammals has shown that the intrinsic muscles can best be regarded as a ‘laminated segmental system’ with tightly packed layers of the ‘transverse’, ‘longitudinal’, and ‘vertical’ muscle fibers. Each segment receives separate innervation from branches of the hypoglosssal nerve. These new anatomical findings are contributing to the development of functional models of the tongue, many based on increasingly refined finite element modeling techniques. They also begin to explain the observed behavior of the jaw-hyoid-tongue complex, or the hyomandibular ‘kinetic chain’, in feeding and consecutive speech. Similarly, major efforts, involving many imaging techniques (cinefluorography, ultrasound, electro-palatography, NMRI, and others), have examined the spatial and temporal relationships of the tongue surface in sound production. The feeding literature shows localized tongue-surface change as the process progresses. The speech literature shows extensive change in tongue shape between classes of vowels and consonants. Although there is a fundamental dichotomy between the referential framework and the methodological approach to studies of the orofacial complex in feeding and speech, it is clear that many of the shapes adopted by the tongue in speaking are seen in feeding. It is suggested that the range of shapes used in feeding is the matrix for both behaviors.
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Thribhuvanan, Dr Lakshmi, Dr M. S. Saravankumar, and Dr Anjana G. "A Short Update of Frankel Functional Regulator." ENVIRO Dental Journal 3, no. 1 (June 30, 2021): 06–12. http://dx.doi.org/10.12944/edj.03.01.03.
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A removable appliance is a device that modifies mandibular posture and transmits the resultant forces created by muscles and soft tissues to underlying and surrounding anatomical structures in a controlled manner. The resulting variation of the neuromuscular environment thus produces the required tooth movement along with the needed advancements in growing patterns. The necessity and requirement of early treatment is to modify the existing and developing malocclusions and muscular derangements before the attainment of growth completion of permanent dentition. Frankel Function Regulator (FR) is a device which functions on the principle of functional orthopedics in unity with muscle gymnastics (muscle exercises) and thereby results in morphological changes in both the jaws hence re-establishing the desirable normal occlusion.
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Kahn, Sandra, Paul Ehrlich, Marcus Feldman, Robert Sapolsky, and Simon Wong. "The Jaw Epidemic: Recognition, Origins, Cures, and Prevention." BioScience 70, no. 9 (July 22, 2020): 759–71. http://dx.doi.org/10.1093/biosci/biaa073.
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Abstract Contemporary humans are living very different lives from those of their ancestors, and some of the changes have had serious consequences for health. Multiple chronic “diseases of civilization,” such as cardiovascular problems, cancers, ADHD, and dementias are prevalent, increasing morbidity rates. Stress, including the disruption of traditional sleep patterns by modern lifestyles, plays a prominent role in the etiology of these diseases, including obstructive sleep apnea. Surprisingly, jaw shrinkage since the agricultural revolution, leading to an epidemic of crooked teeth, a lack of adequate space for the last molars (wisdom teeth), and constricted airways, is a major cause of sleep-related stress. Despite claims that the cause of this jaw epidemic is somehow genetic, the speed with which human jaws have changed, especially in the last few centuries, is much too fast to be evolutionary. Correlation in time and space strongly suggests the symptoms are phenotypic responses to a vast natural experiment—rapid and dramatic modifications of human physical and cultural environments. The agricultural and industrial revolutions have produced smaller jaws and less-toned muscles of the face and oropharynx, which contribute to the serious health problems mentioned above. The mechanism of change, research and clinical trials suggest, lies in orofacial posture, the way people now hold their jaws when not voluntarily moving them in speaking or eating and especially when sleeping. The critical resting oral posture has been disrupted in societies no longer hunting and gathering. Virtually all aspects of how modern people function and rest are radically different from those of our ancestors. We also briefly discuss treatment of jaw symptoms and possible clinical cures for individuals, as well as changes in society that might lead to better care and, ultimately, prevention.
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Gaivoronsky, Ivan V., Maria G. Gaivoronskaya, Oksana M. Fandeeva, and Vladimir A. Shashkov. "Typical features of morphometric parameters of the mandible in adults." Курский научно-практический вестник «Человек и его здоровье», no. 2 (June 2020): 34–41. http://dx.doi.org/10.21626/vestnik/2020-2/05.
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Objective: to develop a classification of mandibular forms and to study typical features of the morphometric characteristics of this bone in adults. Materials and methods. The study was conducted on 150 lower jaws of adults. To determine the shape of the lower jaw, four morphometric parameters were measured: angular width, projection length from the corners, branch height, smallest branch width, and three morphometric indexes were introduced: 1 - the long-length longitudinal index of the lower jaw; 2 - longitude latitudinal index of the body of the lower jaw; 3 - latitudinal-altitude index of the branches of the lower jaw. According to these indices, 9 groups of jaws with different shapes were identified. In these groups, the values of 35 morphometric parameters of the body and branches of the lower jaw were studied. Results. It was found that statistically significant differences (p <0.05) between the groups of jaws, determined by the value of the altitude-longitude index of the lower jaw and the longitude-latitude index of the body of the lower jaw, exist between the same morphometric parameters: angular width, projection length from the corners and chin angle , and most of the morphometric parameters of the body and branches of the lower jaw do not statistically significantly differ between the extreme forms (dolicho- and brachi, lepto- and eurimandibular). There are statistically significant differences between the jaw groups, systematized by the latitude-altitude index of the branch of the lower jaw (p <0.05) for most of the studied indicators of the branch of the lower jaw: branch height, smallest branch width, notch width, notch angle, base of the coronoid process , the base of the condylar process, the distance from the front edge of the lower jaw branch to the opening of the lower jaw, the distance from the notch of the lower jaw to the opening of the lower jaw, the distance from the angle of the lower jaw to the opening of the lower jaw. It has been proved that in the lower jaws with a hypsiramimandibular form, the values of the smallest branch width, the base length of the coronoid and condylar processes, as well as the distance from the front edge of the branch to the opening of the lower jaw are significantly smaller, however, the values of the branch height, notch angle, notch width, notch distance the angle of the lower jaw to its opening is larger compared to the platyramimandibular form (p˂0.05). Conclusion. The greatest number of differences in the value of morphometric parameters is observed during the systematization of the lower jaw according to the shape of its branch. This can be explained by the fact that it is under the direct influence of the masticatory muscles, performing not only supporting, protective, but also motor function.
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Babich, Vasilii V., and Julia A. Bistrova. "Clinical features of prosthetic treatment in edentuluos patients." Russian Journal of Dentistry 25, no. 3 (April 19, 2022): 247–52. http://dx.doi.org/10.17816/1728-2802-2021-25-3-247-252.
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BACKGROUND: Social adaptation of patients with complete absence of teeth is associated with fixation and stabilization of prostheses during chewing and speech. It is necessary to take into account the somatic status of the patient, the causes of tooth loss, pay attention to the clinical stages of orthopedic treatment.
 AIM: Of the study is to increase the efficiency of the orthopedic dentist with full removable prosthetics.
 MATERIAL AND METHODS: The conditions for obtaining a compression impression are a rigid spoon, silicone impression material of medium viscosity, constant pressure at the time of impression removal. The indication for removing the compression impression is the mucous membrane of the 1st type according to the Supple. The conditions for removing decompression impressions are a perforated individual spoon, liquid-flowing impression material, no pressure on the oral mucosa. The indication for the use of decompression impressions is a thin, atrophied mucous membrane of the oral cavity of the 2nd type according to Supple. It is necessary to use functional impressions combined according to the degree of pressure on the oral mucosa. This implies the peculiarities of manufacturing a rigid base with wax rollers. After determining the central ratio of the jaws and packing the template basis with bite rollers, the doctor applies the impression material differentially to its inner surface. Both templates with bite rollers are inserted into the oral cavity, the doctor controls the central position of the lower jaw, while functional impressions are taken from the upper and lower jaws, taking into account the functional pressure of the patients chewing muscles. This will allow you to evenly distribute the chewing pressure on the oral mucosa. The value of functional rest is determined by measuring two marked points at the base of the nose and on the chin and always exceeds the amount of separation in the state of the central ratio of the jaws by the amount of the interclusal space. Having determined the amount of functional rest, they begin to design the maxillary occlusion pattern, then note the anatomical landmarks. Often, the removal of impressions with a corrective silicone mass is performed in the position of the central ratio.
 The value of functional rest is determined by a set of anatomical landmarks in a state of maximum possible muscle relaxation in combination with phonetic tests when closing the lips without tension.
 RESULTS: The determination of the central ratio on rigid bases makes it possible to accurately fix the interalveolar distance. Patients adapt to prosthetic structures faster.
 The use of a facial arch with an articulator significantly improves the quality of the prosthetic structure, allows you to individualize the anatomical parameters of the patient.
 When determining the central ratio of the jaws, checking the design of the future prosthesis, cone-beam computed tomography of the temporomandibular joint was used to control the position of the heads of the lower jaw, confirming the correctness of the actions. At the stage of checking the design of the removable prosthesis, phonetic tests were used.
 CONCLUSION: The use of combined impressions with simultaneous determination of the central ratio of the jaws and control of the position of the heads of the lower jaw can accelerate the process of orthopedic treatment (combining two stages) and adaptation to removable prostheses. To improve speech during treatment, it is necessary to use special phonetic tests that allow you to restore the correct ratio between the jaws, find the optimal position of artificial teeth, determine the boundaries and shape of the basis of the prosthesis and design the optimal prosthesis for each patient.
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Zubkova, A. A., Vitaliy Yu Skorikov, M. S. Grishechkin, and E. V. Izhnina. "EVALUATION OF CLINICAL ASPECTS OF APPEARANCE OF TEETH NONCARIOUS DEFECTS IN BROXISM PATIENTS." Russian Journal of Dentistry 23, no. 2 (April 15, 2019): 59–63. http://dx.doi.org/10.18821/1728-2802-2019-23-2-59-63.
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Purpose - to study the etiology, prevalence, clinical course, functional examination and treatment of non-carious lesions located in the cervical area of patients with bruxism. Materials and methods. A prospective study of 200 outpatient cards of dental patients at the dental clinic of the Federal State Budgetary Educational Institution of Higher Medical Education of the KMGU of the Ministry of Health of Russia (Kursk) and Federal State Budgetary Educational Institution of Higher Medical Care of the Kuban State Medical University of the Ministry of Health of Russia (Krasnodar) in the age range from 18 to 55 years, whose average age was 38 ± 6.7 years. We studied the localization of cervical defects, etiological factors of occurrence, and also conducted an electromyographic study of the chewing muscles at rest, when the jaws were compressed and when chewing. Results. When studying the localization of cervical defects in different functional groups of teeth, defects in the cervical area of premolars were noted in 41 patients - 57%, in 18 - on canines (25%), in 10 - on incisors (13.8%), in 3 - on molars (4.2%). It was revealed that the trigger mechanism was a number of factors: partial loss of teeth (20 patients were diagnosed with partial absence of teeth of both jaws - Kennedy class III-IV without correct orthopedic treatment), 17 respondents had flattened occlusal surfaces of teeth after therapeutic treatment, 31 were diagnosed abrasion of varying severity and localization, in all patients - a violation of occlusal relationships. In 56 patients (77.77 %) a combination of several etiological factors was noted. A comparative analysis of EMG indices of paired masticatory muscles in the studied group showed that before the start of dental treatment, patients had uncontrolled bursts of bioelectric activity (BEA) in opposite muscles from opposite sides, an increase in the amplitude of muscle contractions during compression in both muscles (mostly in actually chewing ), decrease in the amplitude of muscle contractions during compression due to the rapid fatigability of muscles at rest. Conclusion. Thus, questions of etiology are still open and subject to further study. Of the many known causes, the most common are violation of occlusal relationships, muscular parafunctions, external traumatic factors, etc. The appearance of bruxism is associated with a significant risk of disturbing the occlusal relationship with a subsequent increase in the load on the tooth enamel. In this regard, a rational comprehensive dental treatment of patients with the studied combined pathology should be carried out after conducting electromyographic studies with samples of “rest”, “compression” and “chewing” strictly in accordance with the indications and timing of dynamic observation at least 1 time in 3 months.
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Cox, Philip G. "The jaw is a second-class lever in Pedetes capensis (Rodentia: Pedetidae)." PeerJ 5 (August 30, 2017): e3741. http://dx.doi.org/10.7717/peerj.3741.
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The mammalian jaw is often modelled as a third-class lever for the purposes of biomechanical analyses, owing to the position of the resultant muscle force between the jaw joint and the teeth. However, it has been proposed that in some rodents the jaws operate as a second-class lever during distal molar bites, owing to the rostral position of the masticatory musculature. In particular, the infraorbital portion of the zygomatico-mandibularis (IOZM) has been suggested to be of major importance in converting the masticatory system from a third-class to a second-class lever. The presence of the IOZM is diagnostic of the hystricomorph rodents, and is particularly well-developed in Pedetes capensis, the South African springhare. In this study, finite element analysis (FEA) was used to assess the lever mechanics of the springhare masticatory system, and to determine the function of the IOZM. An FE model of the skull of P. capensis was constructed and loaded with all masticatory muscles, and then solved for biting at each tooth in turn. Further load cases were created in which each masticatory muscle was removed in turn. The analyses showed that the mechanical advantage of the springhare jaws was above one at all molar bites and very close to one during the premolar bite. Removing the IOZM or masseter caused a drop in mechanical advantage at all bites, but affected strain patterns and cranial deformation very little. Removing the ZM had only a small effect on mechanical advantage, but produced a substantial reduction in strain and deformation across the skull. It was concluded that the masticatory system of P. capensis acts as a second class lever during bites along almost the entire cheek tooth row. The IOZM is clearly a major contributor to this effect, but the masseter also has a part to play. The benefit of the IOZM is that it adds force without substantially contributing to strain or deformation of the skull. This may help explain why the hystricomorphous morphology has evolved multiple times independently within Rodentia.
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Nor Masitah Mohamed Shukri, Santhosh Kumar M P, and Arthi Balasubramaniam. "Prevalence of Temporomandibular Joint Disorders Among Dental Patients in A Private Institution." International Journal of Research in Pharmaceutical Sciences 11, SPL3 (October 10, 2020): 1309–15. http://dx.doi.org/10.26452/ijrps.v11ispl3.3383.
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Temporomandibular joints (TMJ) are the bilateral synovial articulation between temporal bone and lower jaw, seen on each side of the jaws. Temporomandibular joint disorders (TMD) can be defined as the tenderness of the jaws and dysfunction of the associated muscles of mastication and the temporomandibular joints, which connect the mandible to the skull. The exact cause of TMD still remains mysterious and unclear. However, the possible attributes of TMD are arthritis, trauma or blow to the TMJ, excessive gum chewing and bruxism. Patients are usually treated with ice packs, gentle massage at the jaw area and prescription of nonsteroidal anti-inflammatory drugs (NSAIDs). This study sought to evaluate the incidence rate, age and gender differences of TMD among patients reporting to Saveetha Dental College and Hospital. The following parameters were evaluated based on the dental records; age, gender and types of TMD. Excel tabulation and SPSS version 23 was used for data analysis. The prevalence of temporomandibular disorders was higher in female patients (51.9%) than male patients (48.1%). The most frequent age group affected by temporomandibular disorders was 31-40 years (36.7%). Disc-condyle disorder (75.9%) is the most frequent sub-type of temporomandibular disorders present in the patients. There was no statistically significant correlation between age and TMD (p=0.847); and gender and TMD (p=0.365). It can be concluded that within the limits of study, TMD was present in adulthood and was more common in women, with disc-condyle disorder being the most prevalent type.
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Spolaor, Fabiola, Martina Mason, Alberto De Stefani, Giovanni Bruno, Ottavia Surace, Annamaria Guiotto, Antonio Gracco, and Zimi Sawacha. "Effects of Rapid Palatal Expansion on Chewing Biomechanics in Children with Malocclusion: A Surface Electromyography Study." Sensors 20, no. 7 (April 7, 2020): 2086. http://dx.doi.org/10.3390/s20072086.
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Malocclusion during childhood may affect both morphology and masticatory function and could greatly affect the subsequent growth and development of the jaws and face. The purpose of this study was to evaluate the efficiency of surface electromyography in describing the effects of the rapid palatal expansion (RPE) on Masseter (M) and Temporalis Anterior (T) muscles’ activity in 53 children with different types of malocclusion: bilateral posterior crossbite (BPcb), underdeveloped maxillary complex without crossbite (NOcb) and unilateral posterior crossbite on the right (UPCBr) and on the left (UPCBl). The muscular activities during chewing tasks were assessed bilaterally before and after RPE application and three months after removal. Both the envelope’s peak (µV) and its occurrence (% of chewing task) were extracted from the surface electromyography signal. Our results showed the presence of statistically significant differences (p < 0.05) on temporomandibular joint muscles, across different assessments, in all the tested populations of subjects. Surface electromyography demonstrated a relationship between the correction of a maxillary transverse discrepancy and the restoration of a muscle’s activation patterns comparable to healthy subjects for both T and M.
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Aksyonov, D. I., Yu N. Mayboroda, E. A. Bragin, and I. N. Aksyonov. "Myofunctional parameters in patients using full removable dentures with progenic and prognathic ratio of the anterior segments of the edentulous jaws." Stomatology for All / International Dental review, no. 2021 3 96 (September 2021): 27–31. http://dx.doi.org/10.35556/idr-2021-3(96)27-31.
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The aim study was to construct artificial dentitions based on the method of mathematical modeling with the progenic and prognatic ratios of toothless frontal segments and to analyze the functional activity of the masticatory muscles in patients using dentures made in this way, compared with standard prosthetic structures. To compare and interpret the data obtained, electromyographic studies were performed in the control group (16 people), whose teeth were made using the traditional method, and the main group (22 people), whose artificial teeth were formed according to individual mathematical calculations, taking into account the size of the sagittal gap of the frontal segments of the progenic and prognatic ratio of toothless jaws. Statistical processing of the results of the electro-myographic study was carried out using the Statistica application software package. The digital data were processed by the method of variational statistics using the Student's t-test. The analysis of the obtained data showed the advantages of using individual mathematical calculations when solving the issue of tactics for constructing dentitions in the frontal segment of toothless jaws, taking into account the degree of the sagittal gap in the progenic and prognatic correlation of the jaws and their possible combinations.
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Anderson, Philip S. L., and Mark W. Westneat. "Feeding mechanics and bite force modelling of the skull of Dunkleosteus terrelli , an ancient apex predator." Biology Letters 3, no. 1 (November 28, 2006): 77–80. http://dx.doi.org/10.1098/rsbl.2006.0569.
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Placoderms are a diverse group of armoured fishes that dominated the aquatic ecosystems of the Devonian Period, 415–360 million years ago. The bladed jaws of predators such as Dunkleosteus suggest that these animals were the first vertebrates to use rapid mouth opening and a powerful bite to capture and fragment evasive prey items prior to ingestion. Here, we develop a biomechanical model of force and motion during feeding in Dunkleosteus terrelli that reveals a highly kinetic skull driven by a unique four-bar linkage mechanism. The linkage system has a high-speed transmission for jaw opening, producing a rapid expansion phase similar to modern fishes that use suction during prey capture. Jaw closing muscles power an extraordinarily strong bite, with an estimated maximal bite force of over 4400 N at the jaw tip and more than 5300 N at the rear dental plates, for a large individual (6 m in total length). This bite force capability is the greatest of all living or fossil fishes and is among the most powerful bites in animals.
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Camp, Ariel L. "What Fish Can Teach Us about the Feeding Functions of Postcranial Muscles and Joints." Integrative and Comparative Biology 59, no. 2 (April 27, 2019): 383–93. http://dx.doi.org/10.1093/icb/icz005.
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Abstract Studies of vertebrate feeding have predominantly focused on the bones and muscles of the head, not the body. Yet, postcranial musculoskeletal structures like the spine and pectoral girdle are anatomically linked to the head, and may also have mechanical connections through which they can contribute to feeding. The feeding roles of postcranial structures have been best studied in ray-finned fishes, where the body muscles, vertebral column, and pectoral girdle attach directly to the head and help expand the mouth during suction feeding. Therefore, I use the anatomy and motion of the head–body interface in these fishes to develop a mechanical framework for studying postcranial functions during feeding. In fish the head and body are linked by the vertebral column, the pectoral girdle, and the body muscles that actuate these skeletal systems. The morphology of the joints and muscles of the cranio-vertebral and hyo-pectoral interfaces may determine the mobility of the head relative to the body, and ultimately the role of these interfaces during feeding. The postcranial interfaces can function as anchors during feeding: the body muscles and joints minimize motion between the head and body to stabilize the head or transmit forces from the body. Alternatively, the postcranial interfaces can be motors: body muscles actuate motion between the head and body to generate power for feeding motions. The motor function is likely important for many suction-feeding fishes, while the anchor function may be key for bite- or ram-feeding fishes. This framework can be used to examine the role of the postcranial interface in other vertebrate groups, and how that role changes (or not) with morphology and feeding behaviors. Such studies can expand our understanding of muscle function, as well as the evolution of vertebrate feeding behaviors across major transitions such as the invasion of land and the emergence of jaws.
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Terekhova, Kseniya A., Denis A. Kuznetsov, Mikhail A. Postnikov, Nikolai Yu Oborotistov, and Galina V. Kuznetsova. "Assessment of the functional state of the maxillofacial muscles and morphological parameters of the dental system in patients with sagittal occlusion abnormalities." Aspirantskiy Vestnik Povolzhiya 20, no. 5-6 (July 15, 2020): 89–96. http://dx.doi.org/10.17816/2072-2354.2020.20.3.89-96.
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The article analyzes the morphological parameters of the maxillofacial system and muscle tone indicators of the maxillofacial region in patients with a gnatic form of distal occlusion. Correlation analysis of morphological and functional indicators was performed. We examined 22 patients aged 18-25 years with a gnatic form of distal occlusion of the dentition. The examination included clinical examination, cephalometric analysis with the SimplyCeph program, anthropometric analysis of cast dental models, and the functional method of research-myotonometry. Analysis of the results demonstrates decrease in the angular and linear parameters that characterizes the longitudinal dimensions of the lower jaw and the vertical dimensions of the jaws, the total angle of the Bjork and the basal angle. When analyzing the correlation relationship, the relationship between morphological and functional parameters has been noted.
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Anderson, Philip S. L., and Mark W. Westneat. "A biomechanical model of feeding kinematics forDunkleosteus terrelli(Arthrodira, Placodermi)." Paleobiology 35, no. 2 (2009): 251–69. http://dx.doi.org/10.1666/08011.1.
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Biomechanical models illustrate how the principles of physics and physiology determine function in organisms, allowing ecological inferences and functional predictions to be based on morphology. Dynamic lever and linkage models of the mechanisms of the jaw and skull during feeding in fishes predict function from morphology and have been used to compare the feeding biomechanics of diverse fish groups, including fossil taxa, and to test ideas in ecological morphology. Here we perform detailed computational modeling of the four-bar linkage mechanism in the skull and jaw systems ofDunkleosteus terrelli, using software that accepts landmark morphological data to simulate the movements and mechanics of the skull and jaws during prey capture. The linkage system is based on the quadrate and cranio-thoracic joints: Cranial elevation around the cranio-thoracic joint forces the quadrate joint forward, which, coupled with a jaw depressor muscle connecting the jaw to the thoracic shield, causes the jaw to rotate downward during skull expansion. Results show a high speed transmission for jaw opening, producing a rapid expansion phase similar to that in modern fishes that use suction during prey capture. During jaw closing, the model computes jaw and skull rotation and a series of mechanical metrics including effective mechanical advantage of the jaw lever and kinematic transmission of the skull linkage system. Estimates of muscle cross-sectional area based on the largest of five specimens analyzed allow the bite force and strike speed to be estimated. Jaw-closing muscles ofDunkleosteuspowered an extraordinarily strong bite, with an estimated maximal bite force of over 6000 N at the jaw tip and more than 7400 N at the rear dental plates, for a large individual (10 m total length). This bite force capability is among the most powerful bites in animals. The combination of rapid gape expansion and powerful bite meant thatDunkleosteus terrellicould both catch elusive prey and penetrate protective armor, allowing this apex predator to potentially eat anything in its ecosystem, including other placoderms.
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Tsyhykalo, Oleksandr V., Nataliia B. Kuzniak, Serhij Yu Palis, Roman R. Dmytrenko, and Іgor S. Makarchuk. "PECULIARITIES OF THE SOURCES OF ORIGIN AND MORPHOGENESIS OF THE HUMAN MANDIBLE." Wiadomości Lekarskie 75, no. 4 (2022): 824–30. http://dx.doi.org/10.36740/wlek202204114.
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The aim: To determine the sources and terms of origin, developmental peculiarities and dynamics of ossification of the mandible during the prenatal period of human ontogenesis. Materials and methods: The research was carried out on the specimens of 30 embryos, 30 pre-fetuses and 60 human fetuses at the period from the 9th to the 12th weeks of the intrauterine development, which were studied by microscopic examination. Three-dimensional computer reconstructions of the human pre-fetal head were made. Results: During the 7th week of development the maxillary processes maximum approach the lateral and medial nasal ones; in pre-fetuses 20,0 mm of PCL they join the frontal spindle forming the facial structures (upper jaw and lip, vestibule of the oral cavity, rudiments of dental laminas, and rudiments of dental buds in its distal portions). Osteogenous islets, rudiments of the mimic and masticatory muscles, blood vessels are formed. During the 8th week of development the osseous tissue of the mandible is formed, the alveolar processes are formed. The oral and nasal cavities are isolated in 9-10-week pre-fetuses, the mass of the osseous tissue increases in both jaws, the enamel organs are detached, the angles and rami formed by the hyaline cartilaginous tissue of the mandible are determined, the rudiments of the temporomandibular joints are already seen. During the 11th week of development the osseous base of both jaws become formed. Till the end of the 12th week the osseous tissue begins to replace the hyaline cartilage of the mandibular rami, and the articular heads are formed in the portion of their proximal ends. Conclusions: The mandible in its development is known to be characterized by intra-cartilaginous formation of the bone which starts from the ends of the cartilage gradually displaced by the osseous tissue. It is indicated that both jaws in pre-fetuses 37,0 and 42,0 mm of PCL are presented by the typical cartilaginous tissue, and in pre-fetuses 45,0-50,0 mm of PCL the osseous tissue is already available replacing the cartilaginous one.
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Petrishin, Svitlana, and Z. Ozhohan. "Kappa-splints application for the treatment of pathological dental hard tissues abrasion in combination with dentition defects and dentition deformations." Galician Medical Journal 24, no. 1 (March 20, 2017): 201716. http://dx.doi.org/10.21802/gmj.2017.1.6.
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Research objective: to develop and implement a new clinical method of producing a set of kappa-splints for splint therapy: treatment and prevention of various forms of pathological teeth abrasion in combination with dentition defects and dentition deformations, which will enable to prevent significant disorders in the dentition.Materials and Methods: 36 patients aged 30-59 have been selected for the targeted research with a generalized form of pathological tooth wear in combination with dentition defects and dentition deformations.Results: After studying the movements of conventional hinge axis in articulate heads of TMJ with the help of condylograph «Cadiax Compact», some asynchronous, asymmetrical bias of articulate heads during the movements of the mandible were revealed in patients with pathological tooth wear in combination with dentitiondefects and dentition deformations. While examining, the patients complained about the aesthetic defects due to the abrasion of teeth and the change of their colour, the discomfort while closing, chewing and phonetic disorders. In the clinical picture of these patients, the typical symptoms of TMJ dysfunction can be singled out, such as pain and crunch in joints, fatigue of chewing muscles and pain in the muscles, the displacement of the mandible to the side during vertical movements, a feeling of fullness in the ears, headaches and bruxism. Dentition deformations were presented as a violation of the occlusal curve. The results indicate on the presence of functional TMJ disorders and masticatory muscles dysfunction in pathological teeth abrasion in combination with dentition defects.So, in most cases, temporary prosthesis structures and occlusal splints can be applied to normalize occlusive correlations at the dysfunction of TMJ and masticatory muscles. Gradual lifting of occlusion has been done due to a set of kappa-splints in terms of 14 days, 1 month and 3 months from 1.0 to 5.0 mm to the full restoration of occlusal height, depending on the severity of pathological teeth abrasion. It is the gradual application of a kappa-splints’ set which allows prevention of further tooth wear; it doesn’t influence the periodontium of teeth; it’s aesthetic and does not violate the pronunciation of sounds. The material, which a kappa-splints set is made of, provides better fixation and bite separation with optimal thickness throughout the dentition, which allows the lower jaw to take a position that helps to restore the functional balance of the entire dentition.Conclusions:1. According to the results of the research it has been established that the orthopedic treatment with the help of occlusive splints at the preparatory stage for the patients with occlusive disorders at pathological dental hard tissues abrasion in combination with dentition defects, periodontium tissue disease and dentition deformations are urgent for the normalization of occlusive correlations of the jaws.2. After studying the movements of conventional hinge axis in articulate heads of TMJ with the help of condylograph «Cadiax Compact» and eliminating the symptoms of stress in masticatory muscles of the patients with occlusive disorders at pathological dental hard tissues abrasion, it is the gradual application of a kappa-splints set, made of hard transparent plates of Ercodent Ercodur material (Germany) with a thickness of 1.0 to 5.0 mm, which allows prevention of further tooth wear, normalization of occlusive correlations of the jaws, separating a bite with optimum thickness throughout the dentition, thus the lower jaw takes a position at which the state of functional equilibrium of the entire dentition is restored.
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Khomyn, N. M., A. R. Mysak, I. I. Iglitskej, V. V. Pritsak, N. V. Nazaruk та Y. I. Hrymak. "Етіологічні фактори та наслідки аномалій розвитку зубів і зубного прикусу у собак". Scientific Messenger of LNU of Veterinary Medicine and Biotechnologies 19, № 77 (7 березня 2017): 18–21. http://dx.doi.org/10.15421/nvlvet7705.
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According to the analysis of literary data it was found that in veterinary dentistry orthodontic disease are common, among which are abnormalities of the teeth and dental bite. The causes of the anomalies of the teeth- jaw apparatus are congenital and acquired. These include hereditary, genetic abnormalities, insufficient development of chewing muscles, insufficient root resorbtion of deciduous teeth, reducing the size of the jaws and gums for virtually no altered the shape of the teeth, errors in diet (soft and liquid feed, calcium deficiency), developmental disability, training with the wrong load on the teeth of young animals, deficiency of minerals in the diet, late change of teeth, tooth size discrepancy to jaws sizes, too large molars and so on. Hyperdontia, olihodontia, convergence, retention are registered among anomalies of the teeth. Violation of the number of teeth, the formation and eruption of teeth are referred to the abnormalities of teeth. Violation of the formation of teeth consists of enamel and dentine dysplasia. To the violation of the teething belong: retention, false polilentia, primary or secondary wolf mouth, dysplasia of temporomandibular joints, cranio-mandibular osteopathy (QS). Furthermore we pay attention to the displacement of the tooth crown and crown slope of (retroposition, vestposition, torpoposition, supraposition, infraposition, mezioposition). To the malocclusion in dogs belong: прогнатию, прогенію, direct bite (central occlusion), anterior cross bite, crooked bite, the open bite, alveolar bite, floating (not constant), skewed bite, mixed bite. Malocclusion of teeth and other problems could cause injury to soft tissue, cause pain and to promote the emergence and development of severe periodontal disease.
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Agarwal, Anmol. "The Headache Tale: An Unknown Link between the Head and Neck Muscles, Jaws and the Teeth." Acta Scientific Otolaryngology 3, no. 8 (July 1, 2021): 01. http://dx.doi.org/10.31080/asol.2021.03.0288.
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PAXTON, HANNELORE. "Phylogeny of Eunicida (Annelida) based on morphology of jaws." Zoosymposia 2, no. 1 (August 31, 2009): 241–64. http://dx.doi.org/10.11646/zoosymposia.2.1.18.
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Eunicida have a complex jaw apparatus with a fossil record dating back to the latest Cambrian. Traditionally, Eunicidae, Onuphidae, and Lumbrineridae were considered closely related families having labidognath maxillae, whereas Oenonidae with prionognath type maxillae were thought to be derived. Molecular phylogenies place Oenonidae with Eunicidae/Onuphidae, and Lumbrineridae as the most basal taxon. Re-evaluation of the jaw types based on morphology and ontogeny demonstrated that the labidognaths Eunicidae and Onuphidae have a closer relationship to the prionognath Oenonidae than was previously thought. Lumbrineridae are neither labidognath nor prionognath; therefore a new type, Symmetrognatha, is proposed. Homologies of jaw elements and considerations of functional aspects of the jaw apparatus are explored to present a hypothesis of the Eunicida phylogeny. The earliest fossils are of placognath and ctenognath types, lacking maxillary carriers. While the former are extinct, the latter are represented by the extant Dorvilleidae. The interpretation of relationships between the carrier-bearing families depends on whether the carriers are thought to have evolved once only or twice independently. The similarity of the carrier structure and their associated muscles suggests the former, placing the Lumbrineridae as sister to Eunicidae/Onuphidae and Oenonidae. However, the ontogeny of the eunicid/onuphid apparatus as well as its adult structure differ greatly from those of lumbrinerids, indicating that the lumbrinerid carriers may have evolved independently and earlier than in eunicids/onuphids and oenonids.
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Bukovic, Dino, Igor Glavicic, Goran Dimitric, Miroslav Smajic, Bozana Radanovic, and Biljana Vitosevic. "Assessing temporomandibular disorders: Mouthpiece design considerations." Vojnosanitetski pregled 75, no. 8 (2018): 756–63. http://dx.doi.org/10.2298/vsp160405362b.
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Background/Aim. Scuba diving is one of the sports with the fastest growing popularity. Nowadays doctors of dental medicine meet divers-patients in their offices more often. Treatment of these patients has some specific features that are related to difficulties in the temporomandibular joint, masticatory muscles and soft tissues of the oral cavity. A set of those complaints represent a condition called ?diver's mouth syndrome?. Most scuba divers complain of temporomandibular joint and the masticatory muscles pain; inadequate mouthpieces can exacerbate temporomandibular dysfunction (TMD) even when its symptoms are not present in everyday life. The aim of this research was to find a decent substitute for a fully customised mouthpiece, that are not present at our market, to discover the qualities of a good mouthpiece and establish prevalence of TMD among divers. Methods. This study included 30 scuba divers. Scuba divers filled out the questionnaire before diving, then dived twice with each of the 3 different commercial mouthpieces provided for this research (Mares Universal, Seac sub, Mares LiquidSkin (Universal Mares, Seac sub, Mares LiquidSkin). After diving, they filled out the second part of the questionnaire and so they performed an assessment of the mouthpiece and gave insight into the prevalence of TMD symptoms caused by using the mouthpiece. Results. According to the average score of satisfaction (the least present symptoms such as pain, fatigue, and numbness of the masticatory muscles and the jaw joint), this research proved Mares LiquidSkin mouthpieces to be the best out of the 3 commercial mouthpieces. For its use, average satisfaction score among participants was 7.07 (out of 10) and none of the divers reported jaw and muscle stiffness during and after the dive with this mouthpiece. The smallest percentage of participants reported pain in the orofacial region and discomfort while swallowing when used it in comparison with other mouthpieces. The anatomy and material of the mouthpieces turned out to be an extremely important factor. Conclusion. Several factors contribute to a good mouthpiece design; the choice of material, its elasticity and softness, the thickness and length of the interdental bite platform and the width of the oral screen that is inserted into the vestibule. The preferred material should be soft silicone. The interdental bite platforms should support the posterior teeth and the oral screen should fit the jaws and not be too wide.
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Ignateva, L. A., and N. Kh Khamitova. "Impact of myofunctional disorders of the maxillofacial area on the formation of occlusion pathology in children." Kazan medical journal 100, no. 3 (June 13, 2019): 422–25. http://dx.doi.org/10.17816/kmj2019-422.
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Myodynamic balance of the muscles of maxillofacial area provides required conditions for normal development of dentoalveolar system. Dysfunction of the muscles of facial and oral area is a significant ethiopathogenetic factor of development of anomalies of tooth position and development of upper and lower jaws. Among such factors the most prevalent habits are sucking fingers, mouth breathing (in genetically, anatomically and physiologically caused absence of nasal breathing), incorrect lip seal and infantile swallowing. Position of the tongue in mouth breathing is of particular importance as positioning the tongue between the dental arches causes significant vestibular inclination of the upper incisors. As a result of these changes disocclusion is formed in vertical plane. Additional pressure of stretched buccal muscles during mouth breathing causes narrowing of the dental arches. It is required to mention that many researchers pay attention to decreased bioelectrical activity of masseters in electromyographic study in patients with occlusion anomalies. Formation of this pathology influences not only the general health state (disorder of nasal breathing, swallowing, chewing, sound pronouncing and posture) but also social adaptation of a child. Due to this children require complex approach to the diagnosis and correction of myofanctional disorders of maxillofacial area.
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Skrypa, Olga L., and Yurii L. Bandrivsky. "Determining the frequency of functional disorders of the TMJ in patients with mandible fractures depending on the location." Wiadomości Lekarskie 73, no. 2 (2020): 245–49. http://dx.doi.org/10.36740/wlek202002107.
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The aim: To investigate the frequency of functional TMJ disorders in patients with fractures of the mandible. Materials and methods: To achieve this goal, 111 patients hospitalized in the department of surgical dentistry of the Chernivtsi Regional Clinical Hospital were examined for traumatic fractures of the mandible with functional disorders of the TMJ (occlusive, muscular, articular disorders). The examination of patients with functional disorders was based on Express – the conclusion of the Hamburg Protocol: 1. pain in palpation of joints; 2. pain in palpation of chewing muscles; 3. presence of noises in the joints; 4. violation of the opening trajectory; 5. the opening of the mouth is limited; 6. eccentric occlusion, premature contacts. Statistical processing of research results was carried out using commonly used methods of variation statistics. Results: We found that on average, mandibule fractures showed the highest number of single-function occlusion`s (18.92%) and articular disorders (21.62%) and multifunctional occlusal-articular disorders (20.72%), with the smallest the frequency of one-function muscle`s disorders (4.50%). Multifunctional TMJ disorders «occlusal + muscle» and «muscular-articular» in this contingent of patients were determined, on average, at the same percentages (10.81%). Attention was drawn to the fact that «muscular + articular» dysfunction of the TMJ was diagnosed more frequently with the immobilization of the fragment with the help of osteosynthesis (18,18 ± 4,54%) and with the combined method (15,39 ± 3,84%) than when both jaws are splinted, p <0,05. Conclusions: It was established that in patients with fractures of the jaws of different localization single-functional articular disorders (21.62% of the subjects) and multifunctional «occlusion-articular» disorders (20.72% of the examined) predominated. In this case, the frequency of TMJ dysfunction, to a large extent, depended on the nature of the displacement and the way of immobilization of the fragments of the mandible.
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Iordanishvili, A. K. "Gerontostomatology: from science to clinical medicine (survey)." Endodontics Today 18, no. 3 (October 12, 2020): 71–77. http://dx.doi.org/10.36377/1683-2981-2020-18-3-71-77.
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Aim of the study was, based on the analysis of dissertation research prepared in scientific laboratories and departments of the St. Petersburg Institute of Bioregulation and Gerontology, to present the contribution of the staff of this Institute to the development of modern gerontostomatology. Dissertation research carried out within the walls of the St. Petersburg Institute of Bioregulation and Gerontology in the field of gerontostomatology touched on the pathology of hard tissues and pulp of teeth, rehabilitation in case of tooth loss, periodontal diseases, oral mucosa, injuries and inflammatory diseases of the jaws and peri-maxillary soft tissues, as well as pathology temporomandibular joint and masticatory muscles in elderly and senile people.