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1
Alkadhimi, Aslam. "A novel and simple technique for correcting localised rotations in the early alignment stage." Journal of Orthodontics 47, no. 4 (August 27, 2020): 338–44. http://dx.doi.org/10.1177/1465312520949553.
Повний текст джерелаАнотація:
Correcting severe tooth rotations can be challenging. There are many ways to de-rotate teeth with fixed or removable appliances. Mechanically, the best and most effective way is one that produces a two-force couple system to rotate a tooth around its centre of rotation (longitudinal axis). The aim of this article was to introduce a simple and efficient technique using a closed coil to correct localised tooth rotations in the early alignment stage, utilising a simple two-force couple system. Furthermore, some of the biomechanical principles concerning de-rotation will be revisited.
2
Kaur, Pushappreet. "Hypodontia, Microdontia and Tooth rotation: A rare clinical triad." International Journal of Dental Research 4, no. 2 (October 23, 2016): 57. http://dx.doi.org/10.14419/ijdr.v4i2.6737.
Повний текст джерелаАнотація:
Hypodontia, microdontia and rotations are developmental dental anomalies resulting from genetic and epigenetic disturbances during tooth initiation, morphogenesis and eruption stages; with variable effects on function and dentofacial esthetics depending upon their severity. Hypodontia and microdontia may occur in syndromic or isolated non-syndromic forms based on presence or absence of congenital defects. This article briefly reviews hypodontia, microdontia and tooth rotation; and discusses a rare case presenting combination of these anomalies along with a possible treatment proposal.
3
Gholamalizadeh, Torkan, Sune Darkner, Peter Lempel Søndergaard, and Kenny Erleben. "A multi-patient analysis of the center of rotation trajectories using finite element models of the human mandible." PLOS ONE 16, no. 11 (November 15, 2021): e0259794. http://dx.doi.org/10.1371/journal.pone.0259794.
Повний текст джерелаАнотація:
Studying different types of tooth movements can help us to better understand the force systems used for tooth position correction in orthodontic treatments. This study considers a more realistic force system in tooth movement modeling across different patients and investigates the effect of the couple force direction on the position of the center of rotation (CRot). The finite-element (FE) models of human mandibles from three patients are used to investigate the position of the CRots for different patients’ teeth in 3D space. The CRot is considered a single point in a 3D coordinate system and is obtained by choosing the closest point on the axis of rotation to the center of resistance (CRes). A force system, consisting of a constant load and a couple (pair of forces), is applied to each tooth, and the corresponding CRot trajectories are examined across different patients. To perform a consistent inter-patient analysis, different patients’ teeth are registered to the corresponding reference teeth using an affine transformation. The selected directions and applied points of force on the reference teeth are then transformed into the registered teeth domains. The effect of the direction of the couple on the location of the CRot is also studied by rotating the couples about the three principal axes of a patient’s premolar. Our results indicate that similar patterns can be obtained for the CRot positions of different patients and teeth if the same load conditions are used. Moreover, equally rotating the direction of the couple about the three principal axes results in different patterns for the CRot positions, especially in labiolingual direction. The CRot trajectories follow similar patterns in the corresponding teeth, but any changes in the direction of the force and couple cause misalignment of the CRot trajectories, seen as rotations about the long axis of the tooth.
4
Radeke, Johanna, Annike B. Vogel, Falko Schmidt, Fatih Kilic, Stefan Repky, Jan Beyersmann, and Bernd G. Lapatki. "Trueness of full-arch IO scans estimated based on 3D translational and rotational deviations of single teeth—an in vitro study." Clinical Oral Investigations 26, no. 3 (November 27, 2021): 3273–86. http://dx.doi.org/10.1007/s00784-021-04309-5.
Повний текст джерелаАнотація:
Abstract Objectives To three-dimensionally evaluate deviations of full-arch intraoral (IO) scans from reference desktop scans in terms of translations and rotations of individual teeth and different types of (mal)occlusion. Materials and methods Three resin model pairs reflecting different tooth (mal)positions were mounted in the phantom head of a dental simulation unit and scanned by three dentists and three non-graduate investigators using a confocal laser IO scanner (Trios 3®). The tooth-crown surfaces of the IO scans and reference scans were superimposed by means of best-fit alignment. A novel method comprising the measurement of individual tooth positions was used to determine the deviations of each tooth in the six degrees of freedom, i.e., in terms of 3D translation and rotation. Deviations between IO and reference scans, among tooth-(mal)position models, and between dentists and non-graduate investigators were analyzed using linear mixed-effects models. Results The overall translational deviations of individual teeth on the IO scans were 76, 32, and 58 µm in the lingual, mesial, and intrusive directions, respectively, resulting in a total displacement of 114 µm. Corresponding rotational deviations were 0.58° buccal tipping, 0.04° mesial tipping, and 0.14° distorotation leading to a combined rotation of 0.78°. These deviations were the smallest for the dental arches with anterior crowding, followed by those with spacing and those with good alignment (p < 0.05). Results were independent of the operator’s level of education. Conclusions Compared to reference desktop scans, individual teeth on full-arch IO scans showed high trueness with total translational and rotational deviations < 115 µm and < 0.80°, respectively. Clinical relevance Available confocal laser IO scanners appear sufficiently accurate for diagnostic and therapeutic orthodontic applications. Results indicate that full-arch IO scanning can be delegated to non-graduate dental staff members.
5
Suri, Sunjay, Suteeta Disthaporn, Bruce Ross, Bryan Tompson, Diogenes Baena, David Fisher, and Wendy Lou. "Permanent maxillary central incisor and first molar rotations in the mixed dentition in repaired complete unilateral cleft lip and palate and their relationship with absence of teeth in their vicinity." Angle Orthodontist 88, no. 5 (May 25, 2018): 567–74. http://dx.doi.org/10.2319/121117-856.1.
Повний текст джерелаАнотація:
ABSTRACT Objectives: To describe qualitatively and quantitatively the directions and magnitudes of rotations of permanent maxillary central incisors and first molars in the mixed dentition in repaired complete unilateral cleft lip and palate (UCLP) and study their associations with absence of teeth in their vicinity. Materials and Methods: Dental casts and orthodontic records taken prior to orthodontic preparation for alveolar bone grafting of 74 children with repaired UCLP (53 male, 21 female; aged 8.9 ± 1.0 years) were studied. Directions and magnitudes of permanent maxillary central incisor and first molar rotations were recorded. Tooth absence was confirmed from longitudinal radiographic records. Incisor and molar rotations were analyzed in relation to the absence of teeth in their vicinity. Results: Distolabial rotation of the permanent maxillary central incisor was noted in 77.14% on the cleft side, while distopalatal rotation was noted in 82.19% on the noncleft side. Incisor rotation was greater when a permanent tooth was present distal to the cleft side central incisor, in the greater segment. The permanent maxillary first molar showed mesiopalatal rotation, which was greater on the cleft side and when there was absence of one or more teeth in the buccal segment. Conclusions: Presence and absence of teeth were associated with the severity of incisor and molar rotations in UCLP. Crowding of anterior teeth in the greater segment was associated with a greater magnitude of rotation of the cleft side permanent central incisor. Absence of one or more buccal segment teeth was associated with greater magnitude of rotation of the molar.
6
Wang, Bao Ming, Xue Song Mei, Zai Xin Wu, and Chi Bing Hu. "Tooth-Leap Shaping Method for Helical Gears." Applied Mechanics and Materials 217-219 (November 2012): 1769–73. http://dx.doi.org/10.4028/www.scientific.net/amm.217-219.1769.
Повний текст джерелаАнотація:
In order to reduce cyclic variation in rotational speed of generated gears or shaper cutter induced by additional rotation during shaping, tooth-leap shaping method for helical gears was proposed. Based on fundamentals of helical gears shaping kinematics, principle of tooth-leap shaping for helical gears was introduced. Furthermore, mathematic models of tooth-leap shaping motions for helical gears are established. Finally, several examples are calculated, results show that cyclic variation in rotational speed of generated helical gear can be reduced largely by tooth-leap shaping method comparing with conventional shaping method. Consequently this method will make shaping motions of helical gears more smooth and improve the machining accuracy of helical gears.
7
Kucevic, Esad, Cena Kajevic, and Mithat Eminovic. "Prevalence of tooth rotation in identical twins." Timocki medicinski glasnik 41, no. 2 (2016): 76–82. http://dx.doi.org/10.5937/tmg1602076k.
Повний текст джерела
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Gromyko, P. N., S. N. Khatetovsky, and I. V. Trusov. "Influence of tooth profile on rotation error of eccentric gearing satellite." Proceedings of the National Academy of Sciences of Belarus, Physical-Technical Series 65, no. 4 (December 31, 2020): 445–52. http://dx.doi.org/10.29235/1561-8358-2020-65-4-445-452.
Повний текст джерелаАнотація:
In the article a cycloid internal engagement of gears that form an eccentric gearing, is considered. This engagement is investigated in point of insensitivity to assembly error. Only one type of assembly error – error of center distance i. e. eccentricity – is considered. It is expanded that workability of gearing with center distance error is provided on the assumption of decrease of diameter of roller that acts as central gear tooth. Roller diameter decrease and center distance error lead to breach of condition of conjugation of gears of eccentric gearing that in turn governs the output member rotation error. IThe output member and rotation transmission mechanism are not considered. Thus output member rotation error is equated to rotation error of eccentric gearing satellite. The influence of tooth profile on rotation error of eccentric gearing satellite is estimated when center distance error. On the base of matrix kinematic the methodology that takes in account the multiple-tooth contact is worked out. On basis of the developed methodology the research of influence of satellite tooth profiles formed on the base of shortened and extended epicycloids on rotation error is carried out. It is determined that in the eccentric gearing the use of satellite tooth profiles, formed on the base of extended epicycloid, makes it possible to decrease the rotation error. At that makes possible the operation of eccentric gearing in general manufacturing settings. Thus, the possibility of extending of eccentric gearing application fields to driving devices with higher requirements to overall sizes, mass, as well as cost, is come.
9
Gromyko, P. N., S. N. Khatetovsky, and I. V. Trusov. "Influence of tooth profile on rotation error of eccentric gearing satellite." Proceedings of the National Academy of Sciences of Belarus, Physical-Technical Series 65, no. 4 (December 31, 2020): 445–52. http://dx.doi.org/10.29235/1561-8358-2020-65-4-445-452.
Повний текст джерелаАнотація:
In the article a cycloid internal engagement of gears that form an eccentric gearing, is considered. This engagement is investigated in point of insensitivity to assembly error. Only one type of assembly error – error of center distance i. e. eccentricity – is considered. It is expanded that workability of gearing with center distance error is provided on the assumption of decrease of diameter of roller that acts as central gear tooth. Roller diameter decrease and center distance error lead to breach of condition of conjugation of gears of eccentric gearing that in turn governs the output member rotation error. IThe output member and rotation transmission mechanism are not considered. Thus output member rotation error is equated to rotation error of eccentric gearing satellite. The influence of tooth profile on rotation error of eccentric gearing satellite is estimated when center distance error. On the base of matrix kinematic the methodology that takes in account the multiple-tooth contact is worked out. On basis of the developed methodology the research of influence of satellite tooth profiles formed on the base of shortened and extended epicycloids on rotation error is carried out. It is determined that in the eccentric gearing the use of satellite tooth profiles, formed on the base of extended epicycloid, makes it possible to decrease the rotation error. At that makes possible the operation of eccentric gearing in general manufacturing settings. Thus, the possibility of extending of eccentric gearing application fields to driving devices with higher requirements to overall sizes, mass, as well as cost, is come.
10
Ishida, Yoshiki, Yukinori Kuwajima, Cliff Lee, Kaho Ogawa, John D. Da Silva, and Shigemi Ishikawa-Nagai. "Effect of Magnet Position on Tipping and Bodily Tooth Movement in Magnetic Force-Driven Orthodontics." Materials 13, no. 16 (August 13, 2020): 3588. http://dx.doi.org/10.3390/ma13163588.
Повний текст джерелаАнотація:
The goal of our study is to launch magnetic force-driven orthodontics. This continuous study investigated the influence of magnet position on tipping and bodily tooth movement, using 3D printing technology and digital analysis. Orthodontic typodont models (TMs) for space-closure were 3D printed to mimic maxillary central incisors. Nd-Fe-B magnets were placed in the middle third (Model-M), and the cervical third (Model-C), of the tooth. TMs, before and after movement, were digitally scanned and superimposed. The 3D digital coordinates (X, Y, and Z axes), and rotations (yaw, pitch, and roll) of the tooth crown and root, were calculated and compared between the two magnet position settings. Model-M showed higher rates of movement, but more rotation than Model-C (p < 0.01). The root apex of Model-M moved in the opposite direction of the crown (R = −0.29), indicating tipping movement. In contrast, the crown and root apex moved in the same direction (R = 0.56) in Model-C, indicating bodily movement. These patterns were confirmed in a typodont model of a moderate crowding case. The results validated that modifying the magnet position increased the amount of bodily tooth movement, and decreased rotation/tipping in an ex vivo setting.
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Raghuveer, HP, M. Hemanth, MS Rani, Chathura Hegde, B. Vedavathi, and D. Chaithra. "An Analysis of the Stress Induced in the Periodontal Ligament during Extrusion and Rotation Movements: A Finite Element Method Linear Study Part I." Journal of Contemporary Dental Practice 16, no. 9 (2015): 740–43. http://dx.doi.org/10.5005/jp-journals-10024-1750.
Повний текст джерелаАнотація:
ABSTRACT Background Orthodontic tooth movement occurs due to various biomechanical changes in the periodontium. Forces within the optimal range yield maximum tooth movement with minimum deleterious effects. Among various types of tooth movements, extrusion and rotational movements are seen to be associated with the least amount of root resorption and have not been studied in detail. Therefore in this study, the stress patterns in the periodontal ligament (PDL) were evaluated with extrusion and rotational movements using the finite element method FEM. Materials and methods A three-dimensional (3D) FEM model of the maxillary incisors was generated using SOLIDWORKS modeling software. Stresses in the PDL were evaluated with extrusive and rotational movements by a 3D FEM using ANSYS software with linear material properties. Results It was observed that with the application of extrusive load, the tensile stresses were seen at the apex, whereas the compressive stress was distributed at the cervical margin. With the application of rotational movements, maximum compressive stress was distributed at the apex and cervical third, whereas the tensile stress was distributed on cervical third of the PDL on the lingual surface. Conclusion For extrusive movements, stress values over the periodontal ligament was within the range of optimal stress value as proposed by Lee, with a given force system by Profitt as optimum forces for orthodontic tooth movement using linear properties. During rotation there are stresses concentrated at the apex, hence due to the concentration of the compressive forces at the apex a clinician must avoid placing heavy stresses during tooth movement. How to cite this article Hemanth M, Raghuveer HP, Rani MS, Hegde C, Kabbur KJ, Vedavathi B, Chaithra D. An Analysis of the Stress Induced in the Periodontal Ligament during Extrusion and Rotation Movements: A Finite Element Method Linear Study Part I. J Contemp Dent Pract 2015;16(9):740-743.
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Medina, S., and A. V. Olver. "An analysis of misaligned spline couplings." Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology 216, no. 5 (May 1, 2002): 269–78. http://dx.doi.org/10.1243/135065002760364813.
Повний текст джерелаАнотація:
The evolution of slip and pressure between the teeth of involute side-fit spline couplings subjected to a steady torque and a rotating misalignment has been studied, using the boundary integral element method. Results show that the tooth load and pressure oscillate during shaft rotation while the teeth undergo a complex cycle of slip. Approximate formulae are provided in order to describe the pressure and wear behaviour of the coupling in terms of dimensionless parameters. The wear pattern on a spline tooth was correctly predicted.
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SHIMODA, Kunio, Hiroshi TAKEMURA, Satoki TSUICHIHARA, Masahiro SHIGETA, Kohei SOGA, Kazuhiro SUGA, Lai wei-jen, Sunmin KIM, Zuisei KANNO, and Motohiro UO. "Relationship between tooth rotation direction and orthodontic moment." Proceedings of JSME annual Conference on Robotics and Mechatronics (Robomec) 2019 (2019): 1P1—A09. http://dx.doi.org/10.1299/jsmermd.2019.1p1-a09.
Повний текст джерела
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Yang, Zhou, Jiaxiang Yu, Jieli Duan, Xing Xu, and Guangsheng Huang. "Optimization-Design and Atomization-Performance Study of Aerial Dual-Atomization Centrifugal Atomizer." Agriculture 13, no. 2 (February 11, 2023): 430. http://dx.doi.org/10.3390/agriculture13020430.
Повний текст джерелаАнотація:
The aerial atomizer is the most essential component of the plant protection UAV (unmanned aerial vehicle). However, the structural optimization of existing aerial atomizers lacks comprehensive consideration of spray parameters and structural parameters, and there is a shortage of available atomizer spray models, resulting in the unstable effect of UAV application. In our previous work, an aerial dual-atomization centrifugal atomizer was developed. In order to obtain an aerial atomizer with good atomization effect and its atomization model, structural optimization at different rotation speeds and flow rates of the atomizer, and its atomization performance, are studied in this paper. Firstly, with the droplet volume median diameter (VMD) and spectral width (SRW) as the evaluation index, through the single-factor, Plackett–Burman and Box–Behnken tests, the influence of rotation speed, flow rate, tooth number and tooth shape were studied. The regression models of the droplet VMD and SRW were established using multiple quadratic regression fitting of the test data. Secondly, in order to achieve the lowest droplet VMD and SRW, the response surface method and post-hoc multiple comparison method were used to obtain the optimized structure of the atomizer’s rotation ring at different rotation speeds (600–7000 mL/min) and flow rates (500–1000 mL/min). Lastly, with the effective swath width (ESW) of the optimized atomizer as the evaluation index, through the Box–Behnken test, the influence of rotation speed, flow rate and spray height were studied. The multiple quadratic regression model of ESW was established with the test data. The test results indicated that rotation speed, flow rate and tooth number had a significant effect on droplet VMD and SRW; tooth shape had no significant effect on the droplet VMD and SRW, however, the square tooth shape had the best atomization effect; and rotation speed, flow rate and spray height had a significant effect on ESW. The optimized structural parameters were tooth shape: square, and tooth number: 20. The determination coefficient of the regression model of VMD, SRW and ESW were 0.9976, 0.9770 and 0.9974, respectively, which indicates that the model was accurate, and can evaluate and predict the spray effect. This paper provides an optimized dual-atomization centrifugal atomizer, and its regression models of VMD, SRW and ESW for UAV applications can provide a reference for efficient UAV spraying.
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Raghuveer, HP, M. Hemanth, MS Rani, Chathura Hegde, B. Vedavathi, and D. Chaithra. "An Analysis of the Stress induced in the Periodontal Ligament during Extrusion and Rotation Movements— Part II: A Comparison of Linear vs Nonlinear FEM Study." Journal of Contemporary Dental Practice 16, no. 10 (2015): 819–23. http://dx.doi.org/10.5005/jp-journals-10024-1763.
Повний текст джерелаАнотація:
ABSTRACT Background Optimal orthodontic forces are those which stimulate tooth movement with minimal biological trauma to the tooth, periodontal ligament (PDL) during and alveolar bone. Among various types of tooth movements, extrusion and rotational movements are seen to be associated with the least amount of root resorption and have not been studied in detail. The mechanical behavior of the PDL is known to be nonlinear elastic and thus a nonlinear simulation of the PDL provides precision to the calculated stress values. Therefore in this study, the stress patterns in the PDL were evaluated with extrusion and rotational movements using the nonlinear finite element method (FEM). Materials and methods A three-dimensional (3D) FEM model of the maxillary incisors was generated using SOLIDWORKS modelling software. Stresses in the PDL were evaluated with extrusive and rotational movements by a 3D FEM using ANSYS software with nonlinear material properties. Results It was observed that with the application of extrusive load, the tensile stresses were seen at the apex whereas the compressive stress was distributed at the cervical margin. With the application of rotational movements, maximum compressi vstress was distributed at the apex and cervical third whereas the tensile stress was distributed on cervical third of the PDL on the lingual surface. Conclusion For rotational and extrusion movements, stress values over the periodontal ligament was within the range of optimal stress value as proposed by Lee, with a given force system by Proffit as optimum forces for orthodontic tooth movement using nonlinear properties. During rotation there are stresses concentrated at the apex, hence due to the concentration of the compressive forces at the apex a clinician must avoid placing heavy stresses during tooth movement. How to cite this article Hemanth M, Raghuveer HP, Rani MS, Hegde C, Kabbur KJ, Chaithra D, Vedavathi B. An Analysis of the Stress Induced in the Periodontal Ligament during Extrusion and Rotation Movements—Part II: A Comparison of vs Nonlinear FEM Linear Study. J Contemp Dent Pract 2015; 16(10):819-823.
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Gupta, Sameer, Garima Gupta, Manisha Sharma, Pooja Sharma, Sachin Goyal, and Pradeep kumar. "An Evaluation of the Stress Pattern Distribution for Orthodontic Tooth Movements – A Finite Element Study." Dental Journal of Advance Studies 03, no. 02 (August 2015): 091–96. http://dx.doi.org/10.1055/s-0038-1672021.
Повний текст джерелаАнотація:
Abstract Objectives: This study was conducted to evaluate stress pattern distribution in the periodontal ligament during various orthodontic tooth movements. Methods: A 3 dimensional FEM model of upper central incisor was developed from C.T scan images of the skull excluding the mandible. The principal stress obtained on the periodontal ligament due to various orthodontic loadings (tipping, bodily movement, intrusion, extrusion and rotations) were tested. Results: Intrusion, extrusion and rotation produced stresses concentrated at apex of root. Bodily movement and tipping forces produce stress concentrated at the alveolar crest and not at the root apex. Conclusion: Clinical implications of this study suggests that if the clinician is concerned about placing heavy stresses on the root apex then vertical and rotational forces must be applied with caution.
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Xu, Lizhong, and Wentao Song. "Elastic hydrodynamic lubrication analysis for a sine movable tooth drive." Advances in Mechanical Engineering 10, no. 12 (December 2018): 168781401881410. http://dx.doi.org/10.1177/1687814018814101.
Повний текст джерелаАнотація:
The sine movable tooth drive has small radial dimension such that the heat, caused by friction, becomes an important factor in deciding its load-carrying ability. It is important to determine the amount of tooth lubrication in order to reduce the heat caused by the friction. This study provides equations for the meshing performance and provides the forces for the sine movable tooth drive. Using these equations, the minimum oil film thickness for the drive system is investigated. Results show that the minimum film thickness between the movable tooth and input shaft or shell changes periodically along the input shaft rotation angle. A large movable tooth radius and a movable tooth rotation radius could increase the film thickness between the movable tooth and the input shaft or the shell. In addition, a large speed ratio could increase the film thickness between the movable tooth and the input shaft, but this would also decrease the film thickness between the movable tooth and the shell. A large sine amplitude could increase the film thickness between the movable tooth and the input shaft, but this does not change the film thickness between the movable tooth and the shell. Under normal operation speeds, the hydrodynamic lubrication condition occurs between the movable tooth and the input shaft, and the partial membrane hydrodynamic state occurs between the movable tooth and the shell.
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Sabbagh, Hisham, Sebastian Marcus Heger, Thomas Stocker, Uwe Baumert, Andrea Wichelhaus, and Lea Hoffmann. "Accuracy of 3D Tooth Movements in the Fabrication of Manual Setup Models for Aligner Therapy." Materials 15, no. 11 (May 28, 2022): 3853. http://dx.doi.org/10.3390/ma15113853.
Повний текст джерелаАнотація:
Background: The clinical outcome of aligner therapy is closely related to the precision of its setup, which can be manually or digitally fabricated. The aim of the study is to investigate the suitability of manual setups made for aligner therapy in terms of the precision of tooth movements. Methods: Six dental technicians were instructed to adjust each of eleven duplicate plaster casts of a patient models as follows: a 1 mm pure vestibular translation of tooth 11 and a 15° pure mesial rotation of tooth 23. The processed setup models were 3D scanned and matched with the reference model. The one-sample Wilcoxon signed-rank test (p < 0.05) was used for evaluation. Results: The overall precision of the translational movement covers a wide range of values from 0.25 to 2.26 mm (median: 1.09 mm). The target value for the rotation of tooth 23 was achieved with a median rotation of 9.76° in the apical-occlusal direction. Unwanted movements in the other planes also accompanied the rotation. Conclusions: A manual setup can only be fabricated with limited precision. Besides the very high variability between technicians, additional unwanted movements in other spatial planes occurred. Manually fabricated setups should not be favored for aligner therapy due to limited precision.
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Sahoo, Vineet, and Rathindranath Maiti. "Static load sharing by tooth pairs in contact in internal involute spur gearing with thin rimmed pinion." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 230, no. 4 (March 2016): 485–99. http://dx.doi.org/10.1177/0954406215618424.
Повний текст джерелаАнотація:
Involute toothed internal−external standard gear sets are modeled for load-sharing by the teeth pairs in mesh along the line of contact. An analytical solution is proposed. Considering the rigid body in rotation, it is assumed that angular rotation of a gear with respect to the other gear due to deformation along the line of contact is equal. The sum of the normal loads in all tooth pairs in contacts, which equals to the total transmitted load, is considered constant. All possible deformations such as, tooth bending deflection, tooth compressive (contact) deformation, tooth foundation deflection and tooth shearing deflection are considered in analyses. Detailed tooth geometries are incorporated in modeling. Ultimately, the map of load sharing by tooth pairs in contacts, at different angular position, over a cycle of similar contact pattern, is established. Finally, considering thin rimmed gears, the effects of the rim thickness on load sharing, which is the aim of the present investigation are analyzed and the results are presented in terms of backup ratios.
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Wu, Mingming. "Application Research of Tooth Arrangement Based on Rotation Matrix Calculation and Resistance Detection in Oral." Computational Intelligence and Neuroscience 2022 (May 20, 2022): 1–10. http://dx.doi.org/10.1155/2022/4675181.
Повний текст джерелаАнотація:
The goal of this research was to provide a new approach for analyzing orthodontic teeth arrangement inside oral depending on the rotation matrix computation and resistance detection. The present method includes the following operations within a certain therapy period: first three-dimensional positions of the tooth were evaluated with a pierced laser beam and a three-dimensional system of surface-scanning. Second, the three-dimensional shape data was automatically registered at maxillary 1st molars, and methods of coordinate had been normalized. Third, a translation vector and rotation matrix had been evaluated from automatic registration of two position data of a particular tooth. Fourth, the limited spiral axes of teeth had been measured as the zero rotational dislocation locus; and impressions for a model of the dental cast had been taken at five different points: shortly before and after device was fitted, and ten days, one month, and two months after the treatment started. The results showed that existing analysis approach could more quickly classify a specific tooth's movement by spinning all over and translating along a finite helical axis. It can provide statistical visual three-dimensional data on complex tooth arrangement throughout orthodontic therapy.
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Goutham, B., Sunil Muddaiah, Sanju Somaiah, Muhammad Shafad, and Justin Jolly. "G–technique: An effective and precise method for rapid Derotation of teeth." JOURNAL OF MULTIDISCIPLINARY DENTAL RESEARCH 6, no. 2 (December 20, 2020): 47–49. http://dx.doi.org/10.38138/jmdr/v6i2.10.
Повний текст джерелаАнотація:
Rotations are mesiolingual or distobuccal intra-alveolar displacement of tooth around their long axis. Canine or premolars must often be derotated during fixed appliance therapy. Derotation of posterior teeth provides space which can be utilized for relieving crowding in the anterior region. By correction of these rotations one to three mm of arch length can be gained per side. Biomechanical principles involve application of single or couple of forces for correction of rotation. Rotated teeth can be corrected by removable, semifixed or fixed appliance depending upon the severity of rotation. Whatever the technique used, derotation especially of posterior teeth should be achieved quickly so that the gained space can be used for relieving crowding. Keywords: Derotation; G – Technique; leveling; aligning
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Sia, Sheau Soon, Yoshiyuki Koga, and Noriaki Yoshida. "Determining the Center of Resistance of Maxillary Anterior Teeth Subjected to Retraction Forces in Sliding Mechanics." Angle Orthodontist 77, no. 6 (November 1, 2007): 999–1003. http://dx.doi.org/10.2319/112206-478.
Повний текст джерелаАнотація:
Abstract Objective: To determine the location of center of resistance and the relationship between height of retraction force on power arm (power-arm length) and movement of anterior teeth (degree of rotation) during sliding mechanics retraction. Materials and Methods: Three human subjects with maxillary protrusion were selected for this study. Initial tooth displacements of maxillary right central incisor under sliding mechanics with various heights of retraction forces were measured in vivo using a two-point three-dimensional displacement magnetic sensor device. By calculating the angle of rotation from the displacements measured, the location of the center of resistance was determined. Results: The results suggested that different heights of retraction forces could affect the direction of anterior tooth movement. The higher the retraction force was applied, the lower the degree of rotation (crown-lingual tipping) would be. The tooth rotation was in the opposite direction (from crown-lingual to crown-labial) if the height of the force was raised above the level of the center of resistance. Conclusion: The location of the center of resistance of the maxillary central incisor was approximately 0.77 of the root length from the apex. During anterior tooth retraction with sliding mechanics, controlled crown-lingual tipping, bodily translation movement, and controlled crown-labial movement could be achieved by attaching a power-arm length that was lower, equivalent, or higher than the level of the center of resistance, respectively. The power-arm length could be the most easily modifiable clinical factor in determining the direction of anterior tooth movement during retraction with sliding mechanics.
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Atrushkevitch, V. G., V. N. Tsarev, L. U. Orekhova, L. A. Elizova, and E. S. Loboda. "Comparative evaluation of the effectiveness in plaque removal from the tooth surface by electric toothbrushes with different types of bristle movement." Stomatologist. Minsk, no. 4(31) (December 2018): 58–63. http://dx.doi.org/10.32993/stomatologist.2018.4(31).11.
Повний текст джерелаАнотація:
Supportive periodontal therapy (SPT) is an important factor in maintaining the results of active treatment of periodontal disease. Selection of effective personal hygienic tools is very important in addition to the formation of sustainable hygienic skills in patients. The aim of the study is a comparative assessment of the quality of mechanical removal of a native microbial biofilm with toothbrushes with different types of head rotation and a manual toothbrush. Objects and methods. The extracted teeth were fixed in plaster models, and the vestibular surface of the three teeth was processed for 10 seconds without the use of toothpaste. Tooth № 1 was a control (biofilm was not removed), tooth № 2 was cleaned with a manual toothbrush with an imitation of the Brass method, tooth № 3 was cleaned with a brush with oscillating-rotating movements of bristles. Tooth №4 was brushed with a toothbrush with vibrating types of bristles motion. The enamel-cementum junction of the tooth was taken strictly from the vestibular surface along the central axis of the tooth for studying in a scanning electron microscope. Conclusions. A complete cleaning of the tooth enamel surface from microbial biofilms is not achieved after using a manual toothbrush. Toothbrushes with oscillating-rotating movements of bristles create the phenomenon of “sweeping” of the biofilm fragments into the area of the cementum-enamel junction. The vibrating types of bristles motion maximally clean the cervical area of the tooth.
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Nissilä, Juhani. "Local Regularity Analysis with Wavelet Transform in Gear Tooth Failure Detection." Management Systems in Production Engineering 25, no. 3 (September 26, 2017): 176–82. http://dx.doi.org/10.1515/mspe-2017-0026.
Повний текст джерелаАнотація:
Abstract Diagnosing gear tooth and bearing failures in industrial power transition situations has been studied a lot but challenges still remain. This study aims to look at the problem from a more theoretical perspective. Our goal is to find out if the local regularity i.e. smoothness of the measured signal can be estimated from the vibrations of epicyclic gearboxes and if the regularity can be linked to the meshing events of the gear teeth. Previously it has been shown that the decreasing local regularity of the measured acceleration signals can reveal the inner race faults in slowly rotating bearings. The local regularity is estimated from the modulus maxima ridges of the signal’s wavelet transform. In this study, the measurements come from the epicyclic gearboxes of the Kelukoski water power station (WPS). The very stable rotational speed of the WPS makes it possible to deduce that the gear mesh frequencies of the WPS and a frequency related to the rotation of the turbine blades are the most significant components in the spectra of the estimated local regularity signals.
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CAI, YONGQING, XIAOXIANG YANG, and BINGWEI HE. "INFLUENCE OF FRICTION IN TRANSPARENT TOOTH CORRECTION TREATMENT: FINITE ELEMENT METHOD." Journal of Mechanics in Medicine and Biology 15, no. 04 (August 2015): 1550052. http://dx.doi.org/10.1142/s0219519415500529.
Повний текст джерелаАнотація:
Objective: The objective was to evaluate the effect of frictional forces on the canine's translation and rotation in transparent tooth correction treatment. Materials and Methods: Based on computed tomography (CT) images of the teeth and their supporting tissues, solid models were used to build finite-element models. One canine was simulated translation and rotation in the buccolingual direction by aligners with different friction coefficients. Results: The change of the canine's rotation centers and periodontal ligament (PDL) stress with an increase of the friction coefficient in the two movement types were obtained. Conclusions: Friction coefficient has little effect on the canine's translation movement. While in rotation cases, the small friction coefficient seems to be helpful to gain the body movement type.
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Lin, Chao, Peilu Li, Chunjiang He, and Qingkun Xing. "Contact fatigue model and life prediction of the compound motion curve-face gear pair." Transactions of the Canadian Society for Mechanical Engineering 44, no. 3 (September 1, 2020): 440–51. http://dx.doi.org/10.1139/tcsme-2019-0202.
Повний текст джерелаАнотація:
Different from the common face gear pair fixed rotation motion between intersecting axes, the compound transmission of the curve-face gear is a new motion form, which can convert rotational motion into rotation and movement motion. To solve the contact fatigue life problem of this new motion form gear pair, a new contact fatigue life calculation method of the compound transmission curve-face gear pair was proposed. Based on the space gear engagement principle and the fracture mechanics theory, the theoretical contact fatigue model of the curve-face gear composite transmission was established. Considering that the contact load for every tooth is time-varying in the half-period of the curve-face gear, the contact fatigue life stage of the curve-face gear was divided into crack initiation and crack growth, and the crack growth fatigue life for each tooth was calculated using the finite element method. The curve-face gear pair was processed in the five-axis NC machining center and the compound transmission experiment platform of the curve-face gear was set up to measure the tooth surface dynamic contact stress, and the overall life of the curve-face gear was predicted. The comparison analysis between theoretical and experimental results verified the correctness of the theoretical contact fatigue calculation model.
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Hong, Kyungjae, Won-Hyeon Kim, Emmanuel Eghan-Acquah, Jong-Ho Lee, Bu-Kyu Lee, and Bongju Kim. "Efficient Design of a Clear Aligner Attachment to Induce Bodily Tooth Movement in Orthodontic Treatment Using Finite Element Analysis." Materials 14, no. 17 (August 30, 2021): 4926. http://dx.doi.org/10.3390/ma14174926.
Повний текст джерелаАнотація:
Clear aligner technology has become the preferred choice of orthodontic treatment for malocclusions for most adult patients due to their esthetic appeal and comfortability. However, limitations exist for aligner technology, such as corrections involving complex force systems. Composite attachments on the tooth surface are intended to enable active control of tooth movements. However, unintended tooth movements still occur. In this study, we present an effective attachment design of an attachment that can efficiently induce tooth movement by comparing and analyzing the movement and rotation of teeth between a general attachment and an overhanging attachment. The 3D finite element modes were constructed from CBCT data and used to analyze the distal displacement of the central incisor using 0.5- and 0.75-mm-thick aligners without an attachment, and with general and overhanging attachments. The results show that the aligner with the overhanging attachment can effectively reduce crown tipping and prevent axial rotation for an intended distal displacement of the central incisor. In all models, an aligner with or without attachments was not capable of preventing the lingual inclination of the tooth.
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Okandeji, ME, OM Femi-Akinlosotu, OO Omotosho, and JO Olopade. "Dental pathologies in the nigerian local pigs (Sus scrofa)." Archives of Anatomy and Physiology 7, no. 1 (May 11, 2022): 001–8. http://dx.doi.org/10.17352/aap.000019.
Повний текст джерелаАнотація:
Background: Dental pathologies are noticeable alterations or deviations from normal dental architecture and can be influenced by genetic or environmental factors. This present study aimed to identify and report the dental pathologies in the Nigerian local pig. Materials and methods: The cleaned skulls of 47 local pigs, aged between 3-51 months were assessed for observable dental abnormalities such as missing teeth, fractured teeth, persistent deciduous teeth, dental caries, dental calculus, and tooth rotation. Results: The study revealed that 98% of the skulls had dental attrition while 96% had stained teeth. About 66% had a least a missing tooth while 78% of adult skulls had at least one persistent deciduous tooth. Fractured tooth, dental calculus, dental caries, and tooth rotation were observed in 46.8%, 74.4%, 34% and 21.3%, respectively. The most common persistent deciduous tooth was the second maxillary incisor, whereas the most commonly missed tooth was the first mandibular premolar, which was bilateral in 75% of affected skulls. Dental calculus was not observed on skulls below 6 months, while the incisor tooth was the most affected tooth by dental attrition. Conclusions: The Nigerian local pig, like other breeds, is susceptible to and has dental pathologies. The data obtained from this study will be beneficial to farmers, as early detection of dental abnormalities will promote productivity and reduces economic losses in pig husbandry. It will also be useful to researchers, especially those using pigs in Nigeria as a model for translation research and comparative dental studies.
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Larson, Brent E., Christopher J. Vaubel, and Thorsten Grünheid. "Effectiveness of computer-assisted orthodontic treatment technology to achieve predicted outcomes." Angle Orthodontist 83, no. 4 (November 19, 2012): 557–62. http://dx.doi.org/10.2319/080612-635.1.
Повний текст джерелаАнотація:
ABSTRACT Objective: To evaluate the effectiveness of computer-assisted orthodontic treatment technology to produce the tooth position prescribed by the virtual treatment plan. Materials and Methods: Posttreatment models of 23 patients treated with SureSmile were digitally superimposed on their corresponding virtual treatment plan models utilizing best-fit surface-based registration. Individual tooth-position discrepancies between virtual treatment plan and actual outcome were computed. Discrepancies less than 0.5 mm in mesial-distal, facial-lingual, and vertical dimensions, and less than 2° for crown torque, tip, and rotation were considered clinically ideal. One-sided test of equivalence was performed on each discrepancy measurement, with P < .05 considered statistically significant. Results: Mesial-distal tooth position was clinically ideal for all teeth with the exception of maxillary lateral incisors and second molars. Facial-lingual tooth position was clinically ideal for all teeth except maxillary central incisors, premolars, and molars, and mandibular incisors and second molars. Vertical tooth position was clinically ideal for all teeth except mandibular second molars. For crown torque, tip, and rotation, discrepancy exceeded the limits considered clinically ideal for all teeth except for crown torque on mandibular second premolars and crown tip on mandibular second premolars and first molars. Conclusions: The effectiveness of computer-assisted orthodontic treatment technology to achieve predicted tooth position varies with tooth type and dimension of movement.
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Doeland, Mark, Aidan M. C. Couzens, Philip C. J. Donoghue, and Martin Rücklin. "Tooth replacement in early sarcopterygians." Royal Society Open Science 6, no. 11 (November 2019): 191173. http://dx.doi.org/10.1098/rsos.191173.
Повний текст джерелаАнотація:
Teeth were an important innovation in vertebrate evolution but basic aspects of early dental evolution remain poorly understood. Teeth differ from other odontode organs, like scales, in their organized, sequential pattern of replacement. However, tooth replacement patterns also vary between the major groups of jawed vertebrates. Although tooth replacement in stem-osteichthyans and extant species has been intensively studied it has been difficult to resolve scenarios for the evolution of osteichthyan tooth replacement because of a dearth of evidence from living and fossil sarcopterygian fishes. Here we provide new anatomical data informing patterns of tooth replacement in the Devonian sarcopterygian fishes Onychodu s, Eusthenopteron and Tiktaalik and the living coelacanth Latimeria based on microfocus- and synchrotron radiation-based X-ray microtomography. Early sarcopterygians generated replacement teeth on the jaw surface in a pattern similar to stem-osteichthyans, with damaged teeth resorbed and replacement teeth developed on the surface of the bone. However, resorption grades and development of replacement teeth vary spatially and temporally within the jaw. Particularly in Onychodus , where teeth were also shed through anterior rotation and resorption of bone at the base of the parasymphyseal tooth whorl, with new teeth added posteriorly. As tooth whorls are also present in more stem-osteichthyans, and statodont tooth whorls are present among acanthodians (putative stem-chondrichthyans), rotational replacement of the anterior dentition may be a stem-osteichthyan character. Our results suggest a more complex evolutionary history of tooth replacement.
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Li, Chen-Jung, A. Galip Ulsoy, and William J. Endres. "The Effect of Flexible-Tool Rotation on Regenerative Instability in Machining." Journal of Manufacturing Science and Engineering 125, no. 1 (February 1, 2003): 39–47. http://dx.doi.org/10.1115/1.1536657.
Повний текст джерелаАнотація:
For rotating-tool machining, such as milling, line boring, and cylinder boring, the tool rotation causes the machining force on each tooth to rotate repetitively relative to the inertial coordinate frame. This is quite different than stationary-tool machining, such as turning or boring with a stationary boring bar, in which the force directions are fixed relative to the inertial frame. Although the subject of stability analysis for rotating tools has been studied extensively in milling, the process is intermittent and hence time varying, which leads to analysis methods that are either analytically approximate or employ time-domain simulation. In this paper nonintermittent machining processes that employ a rotating tool are modeled and analyzed in the rotational coordinates both to simplify the stability analysis and to permit an exact solution. Using rotating-bar boring to illustrate, the analytical results show that the stability limits for boring with a rotating boring bar are quite different from those for boring with a stationary boring bar, and the experimental validation is also provided. Furthermore, the results show a discrepancy to exist between the predicted stability limits for the exact and approximate solutions, especially at low spindle speeds. In both cases an explanation is provided based on the analysis presented.
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Gonzales, Carmen, Hitoshi Hotokezaka, Yoshinori Arai, Tadashi Ninomiya, Junya Tominaga, Insan Jang, Yuka Hotokezaka, Motohiro Tanaka, and Noriaki Yoshida. "An In Vivo 3D Micro-CT Evaluation of Tooth Movement After the Application of Different Force Magnitudes in Rat Molar." Angle Orthodontist 79, no. 4 (July 1, 2009): 703–14. http://dx.doi.org/10.2319/071308-366.1.
Повний текст джерелаАнотація:
Abstract Objective: To investigate the precise longitudinal change in the periodontal ligament (PDL) space width and three-dimensional tooth movement with continuous-force magnitudes in living rats. Materials and Methods: Using nickel-titanium closed-coil springs for 28 days, 10-, 25-, 50-, and 100-g mesial force was applied to the maxillary left first molars. Micro-CT was taken in the same rat at 0, 1, 2, 3, 10, 14, and 28 days. The width of the PDL was measured in the pressure and tension sides from 0 to 3 days. Angular and linear measurements were used to evaluate molar position at day 0, 10, 14, and 28. The finite element model (FEM) was constructed to evaluate the initial stress distribution, molar displacement, and center of rotation of the molar. Results: The initial evaluation of PDL width showed no statistical differences among different force magnitudes. Tooth movement was registered 1 hour after force application and gradually increased with time. From day 10, greater tooth movement was observed when 10 g of force was applied. The FEM showed that the center of rotation in the molar is located in the center of five roots at the apical third of the molar roots. Conclusion: The rat's molar movement mainly consists of mesial tipping, extrusion of distal roots, intrusion of mesial root, palatal inclination, and mesial rotation. Although the initial tooth movement after the application of different force magnitudes until day 3 was not remarkably different, 10 g of force produced more tooth movement compared with heavier forces at day 28.
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Kuleshkov, Yuri V., Timofey V. Rudenko, Mikhailo V. Krasota, Miroslav Bošanský, and František Tóth. "Performance Features of Tooth Gearing in Gear Hydraulic Machines." Acta Technologica Agriculturae 24, no. 2 (May 21, 2021): 84–91. http://dx.doi.org/10.2478/ata-2021-0014.
Повний текст джерелаАнотація:
Abstract The paper presented determines that the rotation velocities of gears and radii connecting the axes of rotation of the gears with the point of their teeth gearing are not equal with each other. It is explained by the relative slip of involute gear profiles during their rolling. This phenomenon will become a prerequisite for further development of creation of mathematical models in the context of theory of gear hydraulic machines. The models can explain a number of specific phenomena in the operation of gear hydraulic machines, such as pressure and input pulsations, dynamics of hydraulic oil in the cut-off plane, combined torque pulsations in gear hydraulic motors and others.
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Grünheid, Thorsten, Charlene Loh, and Brent E. Larson. "How accurate is Invisalign in nonextraction cases? Are predicted tooth positions achieved?" Angle Orthodontist 87, no. 6 (July 7, 2017): 809–15. http://dx.doi.org/10.2319/022717-147.1.
Повний текст джерелаАнотація:
ABSTRACT Objective: To evaluate the accuracy of Invisalign technology in achieving predicted tooth positions with respect to tooth type and direction of tooth movement. Materials and Methods: The posttreatment models of 30 patients who had nonextraction Invisalign treatment were digitally superimposed on their corresponding virtual treatment plan models using best-fit surface-based registration. The differences between actual treatment outcome and predicted outcome were computed and tested for statistical significance for each tooth type in mesial-distal, facial-lingual, and occlusal-gingival directions, as well as for tip, torque, and rotation. Differences larger than 0.5 mm for linear measurements and 2° for angular measurements were considered clinically relevant. Results: Statistically significant differences (P < .05) between predicted and achieved tooth positions were found for all teeth except maxillary lateral incisors, canines, and first premolars. In general, anterior teeth were positioned more occlusally than predicted, rotation of rounded teeth was incomplete, and movement of posterior teeth in all dimensions was not fully achieved. However, except for excess posttreatment facial crown torque of maxillary second molars, these differences were not large enough to be clinically relevant. Conclusions: Although Invisalign is generally able to achieve predicted tooth positions with high accuracy in nonextraction cases, some of the actual outcomes may differ from the predicted outcomes. Knowledge of dimensions in which the final tooth position is less consistent with the predicted position enables clinicians to build necessary compensations into the virtual treatment plan.
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Shcherbakov, N. R., А. M. Bubenchikov, and S. M. Kazakavitschyus. "Mathematical Modelling of an Arch Tooth Surface as an Envelope." Applied Mechanics and Materials 756 (April 2015): 442–46. http://dx.doi.org/10.4028/www.scientific.net/amm.756.442.
Повний текст джерелаАнотація:
We consider a gear with parallel rotation axes of an input and output part (spur gear), the input part having so-called arch teeth. We found the equation of the surfaces family for the arch tooth, the envelope of which is the tooth surface of the output part. We obtained an analytical solution of the equation that results from the condition of enveloping, which allowed to record parametric equations of the envelope determining the tooth surfaces of the output part.
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Nanjannawar, Girish S., Rupal B. Gadodia, Sharad B. Kamat, and Rutuja Chopade. "Esthetic Correction of Rotated Maxillary Central Incisor by Conservative Approach." World Journal of Dentistry 7, no. 4 (2016): 217–20. http://dx.doi.org/10.5005/jp-journals-10015-1400.
Повний текст джерелаАнотація:
ABSTRACT Tooth rotation is a dental anomaly of position, in which there is a displacement of the tooth within the alveolar bone around its longitudinal axis. Although it is a common finding in the premolar—molar region, rotations of the maxillary centrals are extremely rare and such aberrations are multifactorial in their origin. It is important to have a thorough understanding of such anatomical variation, which can cause occlusal and esthetic problems in patients, to alert the dental surgeons, so that they are well prepared to carry out esthetic and functional rehabilitation of the teeth involved. A successful management of 180° rotated maxillary left central incisor by conservative approach is described here. How to cite this article Nanjannawar GS, Gadodia RB, Kamat SB, Chopade R. Esthetic Correction of Rotated Maxillary Central Incisor by Conservative Approach. World J Dent 2016;7(4):217-220.
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Hsu, Ruei Hung, Yu Ren Wu, and Shih Sheng Chen. "Generation of the Anti-Twist Crowned Helical Gear by Modifying the Gear Rotation Angle in the Hobbing Process." Key Engineering Materials 749 (August 2017): 161–70. http://dx.doi.org/10.4028/www.scientific.net/kem.749.161.
Повний текст джерелаАнотація:
In the gear-hobbing process, the work gear tooth flank is usually longitudinally crowned by varying the center distance between the hob and the work gear. Without crossed angle compensation, however, this center distance variation produces a twisted tooth flank on the work gear. This paper therefore proposes a methodology to reduce this tooth flank twist and achieve anti-twist in longitudinal crowning by modifying the gear rotation angle in the hobbing process which is practiced using a CNC hobbing machine with three synchronous axes.
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Wang, Bin, Kai Xu, Shuaipu Wang, Chenxiao Yan, Shuo Chen, Xinfeng Duan, and Shutao Zhang. "Solution of numerical control motion and experiment for machining split equal-base circle bevel gear." Advances in Mechanical Engineering 14, no. 3 (March 2022): 168781402210753. http://dx.doi.org/10.1177/16878140221075307.
Повний текст джерелаАнотація:
The purpose of this study is to realise numerical control (NC) gear cutting on the split wheel blank of equal-base bevel gears, based on the instantaneous cutter position information in tooth surface forming and NC machining theory, the coordinate system of split equal-base bevel gears is established. According to the movement of tool centre coordinate and its transformation, the linear motion of machine tool is solved. By the rotation and translation of the tool axis vector, the solution of the rotary motion of the machine tool is obtained. According to the different rotation direction and concave-convex property of tooth surface, the calculating model of the starting point of processing of each tooth surface is deduced. The complete machining trajectory is formed by analysis and extension of the tool starting point and terminal point of machining, and the automatic generation of the NC machining program is realised. Finally, the simulation of gear cutting on the split wheel blank is carried out using VERICUT software. The experimental and tooth surface measurement results show that the mathematical model of motion trajectory is correct and the machining method is feasible.
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Michalski, Max P., Tonya W. An, Edward T. Haupt, Brandon Yeshoua, Jari Salo, and Glenn Pfeffer. "Abnormal Bone Morphology in Charcot-Marie-Tooth Disease." Foot & Ankle International 43, no. 4 (December 15, 2021): 576–81. http://dx.doi.org/10.1177/10711007211055460.
Повний текст джерелаАнотація:
Background: Although long suspected, it has yet to be shown whether the foot and ankle deformities of Charcot-Marie-Tooth disease (CMT) are generally associated with abnormalities in osseous shape. Computed tomography (CT) was used to quantify morphologic differences of the calcaneus, talus, and navicular in CMT compared with healthy controls. Methods: Weightbearing CT scans of 21 patients (27 feet) with CMT were compared to those of 20 healthy controls. Calcaneal measurements included radius of curvature, sagittal posterior tuberosity-posterior facet angle, and tuberosity coronal rotation. Talar measurements included axial and sagittal body-neck declination angle, and coronal talar head rotation. Surface-mesh model analysis of the hindfoot was performed comparing the average of the CMT cohort to the controls using a CT analysis software (Disior Bonelogic 2.0). Means were compared with a t test ( P < .05). Results: CMT patients had significantly less talar sagittal declination vs controls (17.8 vs 25.1 degrees; P < .05). Similarly, CMT patients had less talar head coronal rotation vs controls (30.8 vs 42.5 degrees; P < .001). The calcaneal radius of curvature in CMT patients was significantly smaller than controls (822.8 vs 2143.5 mm; P < .05). CMT sagittal posterior tuberosity–posterior facet angle was also significantly different from that of controls (60.3 vs 67.9 degrees respectively; P < .001). Surface-mesh model analysis demonstrated the largest differences in morphology at the navicular tuberosity, medial talar head, sustentaculum tali, and anterior process of the calcaneus. Conclusion: This is the first study to quantify the morphologic differences in hindfoot osteology seen in CMT patients. Patients identified with osseous changes of the calcaneus, especially a smaller axial radius of curvature, may benefit from a 3-dimensional osteotomy for correction.
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Fang, Ming Hui. "Numerical Algorithm of Tooth Profile of Noncircular Gear Pair." Applied Mechanics and Materials 201-202 (October 2012): 194–97. http://dx.doi.org/10.4028/www.scientific.net/amm.201-202.194.
Повний текст джерелаАнотація:
According to the generating method theory, noncircular gear with all convex pitch curve can be processed by generating, author designed noncircular gear tooth profile, described a method of precisely calculating noncircular gear tooth profile. And proposed automatically optimizes the noncircular gear tooth profile meshing curve part separately by the identical rack cutting tool different side envelope. Through rack cutting tool along two gear center of rotation segment deviation pitch curve change modified quantity to avoid tooth undercut, realization nonzero modified. The driving gear and the driven gear tooth profile meshing curve part separately by the identical rack cutting tool different side envelope, guarantees when meshing zero clearance. The noncircular gear machined by this method has been used in real machine, which verifies the feasibility of the method.
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Berezhnytskyi, B. S., and M. S. Vorobyov. "KINEMATICS OF A ROLLER CONE BIT WITH A DIRECT FACET TOOTH." PRECARPATHIAN BULLETIN OF THE SHEVCHENKO SCIENTIFIC SOCIETY Number, no. 2(46) (December 26, 2018): 210–17. http://dx.doi.org/10.31471/2304-7399-2018-2(46)-210-217.
Повний текст джерелаАнотація:
The advanced technique of shock-kinematic analysis of the bit roller cone interaction with rock in the process of oil and gas wells drilling is proposed. Preliminary investigations of the interaction of the roller cone bits with rock were based on assumptions far from reality: the concept of the instantaneous axis of rotation of the roller cone constant contact with rock, the absence of slipping, as well as the tooth reforming and sinking into rock. The principle of the roller cones action is the gradual destruction of the surface of the bottomhole due to the cutting-crushing chipping of rock with a bit tooth.The axial roller cone is considered, and the original method of planes projection is used to determine the regulation of tooth motion, taking into account: bit roller cones slipping along the surface of the bottomhole; phases of roller cone tooth sinking into rock; real change in the distance of the axis of rotation of the roller cone to the surface of the bottomhole due to tooth penetration into the rock; the substantiation of the conditions for avoiding the roller cone tooth entering to the previously obtained hole in the process of bottomhole crushing. Besides the moment of the drill string inertia, the moments of roller cones inertia are additionally taken into account under the condition of the oblique impact of the tooth on the rock.The technique allows to calculate the volume of the disintegrated rock on the bottomhole, both taking into account and without taking into account rock chipping and tooth forming. The obtained dependencies allow us to select transmitted ratios from the drill string to the crowns of the roller cones under the condition of avoiding the roller cone tooth to the previously obtained hole during rock destruction on the bottomhole. It allows increasing the efficiency of drilling by roller cones.
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Seo, Jeong-Hee, Emmanuel Eghan-Acquah, Min-Seok Kim, Jeong-Hyeon Lee, Yong-Hoon Jeong, Tae-Gon Jung, Mihee Hong, Won-Hyeon Kim, Bongju Kim, and Sung-Jae Lee. "Comparative Analysis of Stress in the Periodontal Ligament and Center of Rotation in the Tooth after Orthodontic Treatment Depending on Clear Aligner Thickness—Finite Element Analysis Study." Materials 14, no. 2 (January 9, 2021): 324. http://dx.doi.org/10.3390/ma14020324.
Повний текст джерелаАнотація:
Lately, in orthodontic treatments, the use of transparent aligners for the correction of malocclusions has become prominent owing to their intrinsic advantages such as esthetics, comfort, and minimal maintenance. Attempts at improving upon this technology by varying various parameters to investigate the effects on treatments have been carried out by several researchers. Here, we aimed to investigate the biomechanical and clinical effects of aligner thickness on stress distributions in the periodontal ligament and changes in the tooth’s center of rotation. Dental finite element models comprising the cortical and cancellous bones, gingiva, teeth, and nonlinear viscoelastic periodontal ligaments were constructed, validated, and used together with aligner finite element models of different aligner thicknesses to achieve the goal of this study. The finite element analyses were conducted to simulate the actual orthodontic aligner treatment process for the correction of malocclusions by generating pre-stresses in the aligner and allowing the aligner stresses to relax to induce tooth movement. The results of the analyses showed that orthodontic treatment in lingual inclination and axial rotation with a 0.75 mm-thick aligner resulted in 6% and 0.03% higher principal stresses in the periodontal ligament than the same treatment using a 0.05 mm-thick aligner, respectively. Again, for both aligner thicknesses, the tooth’s center of rotation moved lingually and towards the root direction in lingual inclination, and diagonally from the long axis of the tooth in axial rotation. Taken together, orthodontic treatment for simple malocclusions using transparent aligners of different thicknesses will produce a similar effect on the principal stresses in the periodontal ligament and similar changes in the tooth’s center of rotation, as well as sufficient tooth movement. These findings provide orthodontists and researchers clinical and biomechanical evidence about the effect of transparent aligner thickness selection and its effect on orthodontic treatment.
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Seo, Jeong-Hee, Emmanuel Eghan-Acquah, Min-Seok Kim, Jeong-Hyeon Lee, Yong-Hoon Jeong, Tae-Gon Jung, Mihee Hong, Won-Hyeon Kim, Bongju Kim, and Sung-Jae Lee. "Comparative Analysis of Stress in the Periodontal Ligament and Center of Rotation in the Tooth after Orthodontic Treatment Depending on Clear Aligner Thickness—Finite Element Analysis Study." Materials 14, no. 2 (January 9, 2021): 324. http://dx.doi.org/10.3390/ma14020324.
Повний текст джерелаАнотація:
Lately, in orthodontic treatments, the use of transparent aligners for the correction of malocclusions has become prominent owing to their intrinsic advantages such as esthetics, comfort, and minimal maintenance. Attempts at improving upon this technology by varying various parameters to investigate the effects on treatments have been carried out by several researchers. Here, we aimed to investigate the biomechanical and clinical effects of aligner thickness on stress distributions in the periodontal ligament and changes in the tooth’s center of rotation. Dental finite element models comprising the cortical and cancellous bones, gingiva, teeth, and nonlinear viscoelastic periodontal ligaments were constructed, validated, and used together with aligner finite element models of different aligner thicknesses to achieve the goal of this study. The finite element analyses were conducted to simulate the actual orthodontic aligner treatment process for the correction of malocclusions by generating pre-stresses in the aligner and allowing the aligner stresses to relax to induce tooth movement. The results of the analyses showed that orthodontic treatment in lingual inclination and axial rotation with a 0.75 mm-thick aligner resulted in 6% and 0.03% higher principal stresses in the periodontal ligament than the same treatment using a 0.05 mm-thick aligner, respectively. Again, for both aligner thicknesses, the tooth’s center of rotation moved lingually and towards the root direction in lingual inclination, and diagonally from the long axis of the tooth in axial rotation. Taken together, orthodontic treatment for simple malocclusions using transparent aligners of different thicknesses will produce a similar effect on the principal stresses in the periodontal ligament and similar changes in the tooth’s center of rotation, as well as sufficient tooth movement. These findings provide orthodontists and researchers clinical and biomechanical evidence about the effect of transparent aligner thickness selection and its effect on orthodontic treatment.
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Wang, Ke, and Bin Zhao. "The Study of Meshing Performance for Single Screw Compressor Based on Contact Analysis." Applied Mechanics and Materials 16-19 (October 2009): 259–63. http://dx.doi.org/10.4028/www.scientific.net/amm.16-19.259.
Повний текст джерелаАнотація:
In order to increase transmission performance and lubricating condition for meshing pair of the single screw compressor, the contact analysis for the single screw compressor is analyzed. The equations of the former tooth surface of the gate rotor, the back tooth surface of the gate rotor, the top tooth surface of the gate rotor and transition surface between two tooth of gate rotor are constructed respectively. The tooth surface equation of the screw rotor is deduced through using the tooth surface equation of the gate rotor and transform matrix depending on conjugated theory, the contact line equation is moreover acquired. The calculation formula of inducing method curvature is deduced, the inducing method curvature of some points on contact line with the rotation degree of the gate rotor changing is calculated. The computing results show that the contact surface is osculating, which is favor to increase contact strength of the tooth surface. The distribution rules for contact lines of the former tooth surface and back tooth surface of gate rotor is gained through calculation, which provide theory basis for manufacturing screw rotor.
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Nikitopoulos, D. E., V. Eliades, and S. Acharya. "Heat Transfer Enhancements in Rotating Two-Pass Coolant Channels With Profiled Ribs: Part 2—Detailed Measurements." Journal of Turbomachinery 123, no. 1 (February 1, 2000): 107–14. http://dx.doi.org/10.1115/1.1331538.
Повний текст джерелаАнотація:
Detailed heat/mass transfer distributions are presented inside a two-pass rotating ribbed coolant channel for two profiled-rib configurations. Several profiled-rib configurations have been studied (Acharya et al., 2000), and it was found that the best performance was achieved by saw-tooth ribs, and a pyramid–valley rib combination. The profiled ribs were placed directly opposite to each other on the leading and trailing surfaces. Smooth side walls were used in all the experiments. Heat transfer measurements were compared with straight ribs of equal blockage ratio. The measurements were made in a two-pass rotating facility using the naphthalene sublimation mass transfer technique, which provides highly resolved surface distributions. The results presented are for a Reynolds number of 30,000, two rotation numbers (0 and 0.3), and include average heat/mass transfer over the entire inter-rib module as well as detailed heat/mass transfer contours for two profiled-rib cases. Significant enhancement of up to 25 percent in heat/mass transfer was obtained with the pyramid–valley and saw-tooth shaped ribs under rotating conditions.
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Pandis, Nikolaos, Theodore Eliades, Samira Partowi, and Christoph Bourauel. "Moments Generated during Simulated Rotational Correction with Self-Ligating and Conventional Brackets." Angle Orthodontist 78, no. 6 (November 1, 2008): 1030–34. http://dx.doi.org/10.2319/110307-516.1.
Повний текст джерелаАнотація:
Abstract Objective: To assess comparatively the magnitude of moments generated during rotational correction from different bracket systems during the late leveling and alignment stage of orthodontic treatment. Materials and Methods: The three types of brackets assessed were Orthos2 (ORMCO, Glendora, CA), Damon2 (ORMCO), and In Ovation-R (GAC, Bohemia, NY). The brackets were bonded on replicas made of resin from models constructed from an aligned patient's mandibular arch, and a 0.014- × 0.025-inch CuNiTi (ORMCO) wire was inserted. Orthodontic rotational correction was simulated on the Orthodontic Measurement and Simulation System from −5° to +5° rotation in 0.25° increments on the distal and mesial direction. The moments generated at each increment of rotation throughout the full rotation path were statistically analyzed using a two-way analysis of variance and Tukey test at the .05 level of significance. Results: Both bracket type and direction of rotation showed an effect on moment magnitude. The highest moment (27.2 Nmm) was observed for the Damon2 bracket assigned to its noncompliant slot wall door. Higher moments were found during distal premolar rotation. The In Ovation-R showed a magnitude of moment in the range of 9.0 Nmm in the same direction, whereas conventional brackets presented the lowest moments (5.0 Nmm). Conclusions: A wide variation in magnitude of moments exerted by self-ligating and conventional brackets is noted in the simulated rotational correction of teeth, which relates to the geometry of the dental arch, the tooth position, and the rigidity of the closing component of the bracket slot.
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Qiu, Li Jun, and Su Ying Xu. "Powder Particle Cutting Method and Tool Design." Advanced Materials Research 823 (October 2013): 300–303. http://dx.doi.org/10.4028/www.scientific.net/amr.823.300.
Повний текст джерелаАнотація:
The powder particles with a flat-screen multi-tooth cutter blade design. This tool structure is used to glue particles fell legitimate work . Processing tool blade tines arranged in a staggered structure . The tool is a gap in the working conditions . Install the tool in the tool axis rotation is strip knives.Friction surface of the tool can be used strip surface design class . Rotating shaft mounted knives role is to bring people powder particles processing zones . After extrusion and promote the formation of frustration legitimate work . Friction surface knives biggest advantage is the use of a long time. Fixed on a movable carriage mounted flat-screen multi-tooth cutter blade . Fixedly mounted on a movable tool holder . Cutter with carbide knife block . Knives replaceable assembly structure can be used . Mobile holder for the tool replacement and gap adjustment .
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Wang, Ming-Jong. "A New Photoelastic Investigation of the Dynamic Bending Stress of Spur Gears." Journal of Mechanical Design 125, no. 2 (June 1, 2003): 365–72. http://dx.doi.org/10.1115/1.1563636.
Повний текст джерелаАнотація:
In this paper, the maximum tensile bending stress (MTBS) and the critical point in the root fillet of spur gear tooth during transmission are determined by a digital photoelastic system involving real time imaging. The behavioral characteristics of the bending stresses of the gear tooth are analyzed at different rotation speeds, transmitted torques, and contact points. Then, the dynamic effects, the various critical points and the maximum tensile bending stresses are compared experimentally and theoretically, and discussed. Finally, the best approaches for determining the maximum bending stress and its position in the root fillet of spur gear tooth are recommended.
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Zhang, Zhiyuan, Jingbin Li, Xianfei Wang, Yongman Zhao, Shuaikang Xue, and Zipeng Su. "Parameters Optimization and Test of an Arc-Shaped Nail-Tooth Roller-Type Recovery Machine for Sowing Layer Residual Film." Agriculture 12, no. 5 (May 3, 2022): 660. http://dx.doi.org/10.3390/agriculture12050660.
Повний текст джерелаАнотація:
The aim of this paper is to optimize the working parameters of the arc-shaped nail-tooth roller-type recovery machine for sowing layer residual film. Firstly, the tooth roller device of the residual film recovery machine is designed, and the main working parameters affecting the operation of the machine and the value range of each parameter are determined through the analysis of the operation process. Secondly, virtual simulation technology is used to establish a virtual simulation model of the interaction process between the tooth roller device and soil. At the same time, taking the soil-hilling quantity as the index, we build a quadratic regression mathematical model with three factors—the forward speed, rotation speed, and working depth—using the Box–Behnken method. Consequently, the analysis of the simulation results show that the order of the most significant factors is working depth, rotation speed, and forward speed. The optimal combination of working parameters are as follows: a forward speed of 4.5 km/h, a rotation speed of 43.2 r/min, and a working depth of 100.0 mm. Meanwhile, the predicted value of the soil-hilling quantity is 23.1 kg. Finally, we carried out field tests using the optimal combination parameters; the results show that the normal residual film collection rate is 66.8%, the soil-hilling quantity is 24.2 kg, and the relative error between the test value and the predicted value is 4.8%. This indicates that the devised DEM simulation model can be used to predict the operational performance of the tooth roller device in the working process. This study provides a reference that can be used in the planning and boundary enhancement of agricultural machinery and equipment.
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Fan, Yeying, Qian Ma, Guangshun Wei, Zhiming Cui, Yuanfeng Zhou, and Wenping Wang. "TAD-Net: tooth axis detection network based on rotation transformation encoding." Graphical Models 121 (May 2022): 101138. http://dx.doi.org/10.1016/j.gmod.2022.101138.
Повний текст джерела