Dissertations / Theses on the topic 'Three-dimensional scanner'

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A modelagem tridimensional muito já contribuiu com a indústria do entretenimento e agora tem sido amplamente utilizada na manufatura e criação de novos produtos. A possibilidade de se ter um modelo de um produto a um preço menor e com uma maior rapidez tem feito essa técnica ser cada vez mais aceita em todas as áreas da engenharia. Quando já se tem um modelo real e deseja-se realizar alguma modificação, simulação ou mesmo replicar o produto, a engenharia reversa muito pode contribuir, pois permite a obtenção do modelo tridimensional a partir do objeto real. Os equipamentos de digitalização tridimensional têm um alto custo de investimento, mesmo os de baixa precisão. A comunidade de entusiastas de software e hardware livre busca também distribuir e popularizar o conhecimento compartilhando suas descobertas e contribuindo abertamente com outras iniciativas. Buscamos nesse projeto construir um scanner 3D utilizando software e hardware livre utilizando componentes de baixo custo e fácil aquisição, estabelecendo seus limites técnicos, estimulando assim a adoção de técnicas de engenharia reversa. O processo de calibragem, captura e pós tratamento da nuvem de pontos obtidas foi detalhado na construção de modelos para comparação de dimensões e levantamento de características da superfície do material.
The three-dimensional modeling has contributed much to the entertainment industry and has now been widely used in manufacturing and creating new products. The possibility of having a model of a product at a lower price and a higher speed have made this technique is increasingly accepted in all fields of engineering. When there is already a real model and you want to make any changes, simulation or even replicate the product, reverse engineering can greatly contribute, as it allows to obtain three-dimensional model from the real object. The three-dimensional scanning equipment have a high investment cost, even low accuracy. The community of enthusiasts of open source and open hardware also distribute and popularize knowledge sharing his findings and openly contribute to other initiatives. We seek in this study, build a scanner 3D using free software and hardware components using low-cost and easy acquisition, establishing its technical limits, stimulating the adoption of reverse engineering techniques. The calibration, capture and post-treatment process of the cloud of points obtained was detailed in the construction of models for comparison of dimensions and survey of surface characteristics of the material.

Orientador: Ruis Camargo Tokimatsu
Resumo: A modelagem tridimensional muito já contribuiu com a indústria do entretenimento e agora tem sido amplamente utilizada na manufatura e criação de novos produtos. A possibilidade de se ter um modelo de um produto a um preço menor e com uma maior rapidez tem feito essa técnica ser cada vez mais aceita em todas as áreas da engenharia. Quando já se tem um modelo real e deseja-se realizar alguma modificação, simulação ou mesmo replicar o produto, a engenharia reversa muito pode contribuir, pois permite a obtenção do modelo tridimensional a partir do objeto real. Os equipamentos de digitalização tridimensional têm um alto custo de investimento, mesmo os de baixa precisão. A comunidade de entusiastas de software e hardware livre busca também distribuir e popularizar o conhecimento compartilhando suas descobertas e contribuindo abertamente com outras iniciativas. Buscamos nesse projeto construir um scanner 3D utilizando software e hardware livre utilizando componentes de baixo custo e fácil aquisição, estabelecendo seus limites técnicos, estimulando assim a adoção de técnicas de engenharia reversa. O processo de calibragem, captura e pós tratamento da nuvem de pontos obtidas foi detalhado na construção de modelos para comparação de dimensões e levantamento de características da superfície do material.
Mestre

Orientadores: Inacio Maria Dal Fabbro, Adilson Machado Enes
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Agrícola
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Resumo: Técnicas ópticas vêm sendo utilizadas para diversas finalidades técnicas e científicas. Algumas técnicas ópticas se caracterizam como métodos robustos, de baixo custo, não invasivos e não destrutivos para avaliação de materiais diversos, como produtos agrícolas, havendo aplicações desde a engenharia até a área da saúde humana e animal. Neste trabalho propõem-se a avaliação de frutos através da combinação de duas técnicas ópticas cujos estudos vêm comprovando suas aplicabilidades como métodos alternativos e inovadores, os quais empregam equipamentos de baixo custo na aquisição dos dados, permitindo automação de processos de seleção e classificação de produtos. Uma dessas técnicas é conhecida como Biospeckle, a qual fornece informações referentes à qualidade do material biológico em nível de estruturas celulares e a outra é o escaneamento com linha laser, que permite a obtenção de geometria do objeto nos eixos Xi (i = 1,2,3). O objetivo é proceder a um levantamento topográfico digital de materiais biológicos combinando o posicionamento geométrico dos pontos da imagem com informações referentes à atividade biológica. Foi realizada ainda a diferenciação entre frutos de formato variado, a classificação de frutos por formato, classe, coloração e defeitos por meio de processamento de imagens. Dessa forma é possível observar frutos com irregularidades superficiais, maturidade, danos mecânicos e latentes, entre outros. Esta pode se tornar a base para a seleção automática de produtos agrícolas. Foram utilizados um emissor de linha laser de diodo com 632 nm de comprimento de onda, luz branca difusa, câmera CCD, computador, mesa óptica, mamões, peras, tomates e esferas de isopor, bem como softwares ImageJ, Octave, Matlab. Foram desenvolvidos cinco programas computacionais para processamento das imagens. Foram realizados cinco experimentos, a saber: (1) Avaliação da Maturidade de Frutos; (2) Reconstrução Tridimensional e Mapeamento da Bioatividade; (3) Detecção de Formato Variado; (4) Mapeamento por Formato, Classe e Coloração; (5) Detecção de Defeitos. Na Avaliação da Maturidade foram correlacionados índices de maturidade tradicionais (parâmetros de Hunter L a b, pH, Sólidos Solúveis Totais (SST), a relação Sólidos Solúveis Totais e Acidez Total Titulável (SST/ATT), Módulo de Elasticidade, massa e diâmetro) e a técnica óptica Biospeckle, pelo cálculo do Momento de Inércia (MI). Para a Reconstrução Tridimensional os frutos foram rotacionados através de um motor de passo. A cada passo do motor, o fruto foi iluminado pela linha laser projetada e fotografado para obtenção dos dados de geometria e Biospeckle pelo método LASCA (Laser Speckle Contrast Analysis). Foi analisada a correlação entre os índices de maturidade tradicionais e os valores de MI na avaliação da maturidade. Esta tese mostra que é possível avaliar a maturidade dos frutos através do Biospeckle. Obteve-se um mapa tridimensional que integra as informações de topografia e bioatividade do fruto. Obteve-se, ainda, a detecção de formato variado, a classificação de frutos por mapeamento por formato, classe e coloração e detecção de defeitos através de software
Abstract: Optical techniques have been used for both technical and scientific purposes. Optical techniques are usually characterized as being robust, inexpensive, non-invasive and non-destructive methods in to evaluate a diversity of materials which include agricultural derived products. It also shows applications ranging from engineering to human and animal health. In this doctoral dissertation, a new technique to evaluate some fruit properties is proposed. It combines two optical techniques (i.e. Biospeckle and Scan-line laser) whose applicability has been demonstrated as being alternative and innovative. The new proposed technique allows low-cost data acquisition, automation of the entire process, and a proper selection and classification method of vegetable bodies (e.g. fruits). Biospeckle allows obtaining information regarding the quality level of biological material into cellular structures. Scan-line laser enables the attainment of the object geometry on the axes Xi (i=1,2,3). The main purpose of this doctoral dissertation is to obtain a digital survey of biological materials (i.e. papaya, pear and tomato) integrating both geometric positioning and information concerning to its biological activity. The differentiation between different fruit shapes, fruit sorting by size, class, color and defects through image processing was also carried out. Thus it was also possible to observe fruits with surface irregularities, maturity, and mechanical damage, among others. This is the basis proposed for the automatic selection of agricultural products. The following materials were employed in the tests: a line-emitting diode laser with a wavelength of 632 nm, diffuse white light, CCD camera, computer, optical table, papaya, pear and tomato fruits and polystyrene spheres. The softwares utilized were: ImageJ, Octave, Matlab. A total of five computer programs were developed for the image processing procedures. Five experiments were performed: (1) Maturity Assessment of Fruits; (2) Three Dimensional Reconstruction and Mapping of Bioactivity; (3) Miscellaneous Format Detection; (4) Mapping Format, Class and Coloration; (5) Defect Detection. In Maturity Assessment there were correlated traditional methods to verify the maturity (the Hunter parameters L a b, pH, Total Soluble Solids (TSS), the relationship between Total Soluble Solids and Titratable Acidity (TSS/TA), Modulus of Elasticity, weight and diameter) and the optical technique Biospeckle by calculating the Moment of Inertia (MI). For the Three Dimensional Reconstruction the fruits were rotated by a stepper motor. At every step of the motor, the fruit was illuminated by the projected laser line and photographed in order to obtain both geometric and biospeckle data by the LASCA (Laser Speckle Contrast Analysis) method. The correlation between traditional methods for the maturity assessment and values of MI was analyzed. This doctoral dissertation shows that it is possible to evaluate the maturity of fruits through Biospeckle. A three-dimensional map that includes topographical information and bioactivity of the fruit was generated. Also a software can now detect variations in size, classify fruit shapes, color and class as well as defect detection efficiently.
Doutorado
Maquinas Agricolas
Doutora em Engenharia Agrícola

La tesi è focalizzata sulla realizzazione delle indagini geofisiche e topografiche tridimensionali, applicabile sui siti preistorici e basate sull’esempio della Grotta di Fumane (Verona, Italia). I metodi applicati includono la tomografia di resistività elettrica (ERT), le onde sismiche di superficie (HVSR), laser scanner e fotogrammetria. Lo studio ha coinvolto l'uso delle due configurazioni elettrodiche, Wenner-Schlumberger (WSC) e PolePole (PP), sia per avere maggiore risoluzione nei primi 2-3 metri del deposito, sia per ottenere informazioni sulla profondità totale del deposito e la posizione del sostrato roccioso. Le onde sismiche superficiali possono mostrare il rapporto di ampiezza fra gli elementi orizzontali e verticali del moto secondo lo spessore e parametri elastici di strati in prossimità della superficie, variazioni di velocità e fornire informazioni sulla geometria della roccia. Modelli d’inversione 2D e 3D hanno prodotto le immagini suggestive di resistività, che hanno fornito informazioni sul sottosuolo, indicando le aree di bassi valori di resistività che potenzialmente possono contenere il materiale archeologico. Inoltre, la profondità massima dei depositi si crede di essere circa 4-5 metri sulla base delle immagini di resistività Polo-Polo, mentre la profondità massima d’indagine era di circa 8 metri, confermata anche dai dati sismici.  Confrontando i dati della resistività, sismici e archeologici, è possibile caratterizzare meglio la natura del riempimento e di localizzare diversi processi post-deposizionali coinvolti nella creazione del deposito. Laser scanner e rilievo fotogrammetrico hanno fornito il modello tridimensionale della grotta e delle colonne stratigrafiche ad alta risoluzione, che rappresentano il punto di partenza per la modellazione dei dati geofisici. Inoltre, l'indagine dettagliata delle superfici, come pareti della grotta, colonne stratigrafia e le sezioni di scavo, hanno un aspetto importante per la documentazione archeologica, future ricerche, l'interpretazione e l'archiviazione del sito.
The study is focused on implementation of integrated, three-dimensional geophysical and topographical surveys investigation of Early Prehistoric sites on the example of Fumane Cave (Verona, Italy). The methods applied include electrical resistivity tomography (ERT), seismic surface waves (HVSR), laser scanner and photogrammetry. The study involved the use of two resistivity arrays, Wenner-Schlumberger (WSC) and Pole-Pole (PP), both for the shallow resolution in the first 2-3 meters of the deposit and to get information about the total depth and the position of bedrock. Seismic surface-waves may show amplitude resonances at certain frequencies depending on the thickness and elastic parameters of near-surface layers seismic velocity variations and can provide information about the geometry of the bedrock. Two and three-dimensional inversion models provided suggestive resistivity images, that provided detailed information about deposit’s texture spatial characteristics, indicating areas of low resistivity values where potential archaeological materials may be found. Moreover, the maximum depth of the deposits is believed to be around 4-5 m based on the Pole-Pole resistivity images, while the maximum depth of investigation was around 8 meters confirmed by seismic data. Furthermore, by comparing the resistivity, seismic and archaeological data, it is possible to characterise better the nature of sedimentary infill and to locate different post depositional processes involved into the creation of cave deposit. Laser scanner and photogrammetric survey provided georeferenced, high-resolution, three-dimensional, morphologically accurate model of the cave and stratigraphy profiles, serving as a starting point for the modelling of the geophysical data. Furthermore, the detailed survey of the surfaces, such as cave walls, stratigraphy sections and excavation sections, is an important aspect of archaeological data collection, investigation, interpretation and archiving of the site.  

In the last few decades, the field of artificial vision has witnessed an overwhelming growth through academic research and increasing industry demands. One of the more exciting and promising developments in the field has taken form in the 3D vision paradigm. With the advent of 3D vision, the possibility to directly map in three dimensions the shape of an object has opened a wealth of new possibilities. The purpose of this work is to present the theory and design of a low-cost, portable and accurate 3D laser range scanning system. The system allows direct acquisition of 3D images from a scene. The proposed 3D imaging method uses a laser beam for measuring the distance to a target in a fixed point and computing its (X, Y, Z) coordinate in space. Through deflection of this beam using small motorized mirrors, a distant surface may be scanned into a full 3D range image. Unlike conventional ranging systems, the present design uses a single semiconductor laser diode serving as both a laser source and detector. Laser ranging is achieved through frequency modulation of the laser with time-of-flight coherent detection, based on the self-mixing effect in a laser diode. This allows for unambiguous range measurement capabilities over several meters. The benefits of this sensing approach over existing laser-based systems are numerous, and include: (1) Very low cost solution to the ranging problem. (2) No need for external optical sensing elements. (3) Coaxial source and detector configuration eliminates shadowing problems. (4) Coherent detection yields constant ranging error over useful workspace. (5) Velocity and range information available from a single measurement. (6) Interferometric scale measurements possible in fixed-frequency regime.

The state-of-the-art radiotherapy delivery treatments available today require that the intended dose distributions delivered are verified by volumetric gel dosimetry. The development of tissue equivalent gel dosimeters that provide an integrated assessment of the dynamic treatments, are primarily imaged with Magnetic Resonance Imaging (MRI). This thesis describes the dual development and assessment of an optical tomographic scanner and normoxic gel dosimeter. MRI centers are currently limited in both time and resources in providing the routine imaging necessary for treatment verification. An alternative bench top imaging modality has been designed, built and developed to provide both complementary and comparable observations to MRI. It is hoped that this cost effective optical imaging system could alleviate this technological reliance. The optical tomography scanner is evaluated from a series of investigations into the capabilities and limitations of optical tomographic imaging used in conjunction with gel dosimetry. Previously, the manufacture of gel dosimeters required anoxic environments in which the presence of oxygen in the dosimeter is limited. This requirement limited the production of gel dosimeters to chemistry laboratories that possessed the required technical expertise. MRI and optical imaging have been used to investigate the properties, dose response and the batch-to-batch reproducibility of a normoxic MAGIC gel dosimeter. The results obtained are encouraging having shown successfully reconstructed optical images obtained from various dose distributions delivered to the MAGIC gel dosimeter.

The present research was envisioned as a project defined by multiple studies that are strictly correlated each other. The report of the birth, development and practical application to the diagnostic and surgery fields of a novel 3D approach for the computation of femoral measurements was the first aim. Moreover, in the authors’ purpose the description of the translational value of the proposed procedure enhanced with its plausible utility to the daily practice of orthopaedic surgeons, represented another focal point. In this sense, the research started from the validation of the 3D assessment of femoral morphometric parameters. Veterinary literature reports tons of papers describing several methodologies for obtaining femoral measurements through different diagnostic techniques. Furthermore, bibliography presents lot of angles values that are currently adopted and considered as reference parameters for most of the corrective osteotomies. Additionally, in the recent past an increased emphasis on 3D approach grown but little if any attention was devoted to 3D measurements. This trend represented in the authors’ mind the gap with the current knowledge and, thus, an area to be deeply investigated. Indeed, to the best of author knowledge, there were no papers documenting the assessment of 3D femoral axes and angles in veterinary medicine, with no 3D protocol described. In addition, currently available canine femoral measurements related to frontal, sagittal and transverse deformities have only been computed in bi-planar projections, whether acquired from 2D or 3D imaging models. Therefore, starting from the accepted human methods and from the features definition in veterinary literature, we proposed a new approach. The first study was designed to define a 3D methodology, introducing a consistent and quantitative method for the assessment of femoral morphometric parameters in 3D geometrical models. To validate the proposed approach, accurate geometric data were necessary and, therefore, we opted for meshes obtained by a 3D scanner, instead of CT images. Once the validation of the was stated, our focus was directed towards the evaluation of the precision of the proposed 3D protocol. The validation of a novel diagnostic test requires verification of the repeatability, defined as the strength of agreement between repeated measurements of the same samples performed from one examiner, and the reproducibility as well, that express the same variance but between a group of observers. Furthermore, the accuracy of the measurements indicates how close the measurements took with the investigated technique to a true value (gold standard). Therefore, a second project was designed to test the precision of three diagnostic techniques, two largely diffuse (Rx and TC) one recently introduced in veterinary (3D), for the measurement of femoral angles. The second purpose of this study was the investigation of the potential application of the algorithm implemented in a computer-aided-design (CAD) software, using CT data. Considering that for the first study we worked with 3D scanner data, the main aim at this point of the research was represented by the enhancement of the presented 3D protocol for diagnostic purposes. In the author opinion, changing the source of data was necessary because of the availability of CT and MRI equipment in veterinary practice. Finally, the last goal of this project was the translation of the application of 3D computation to the surgical field. The current research contemplates the fact that the augmented interest on 3D computation is not only relevant for diagnostic reasons, but also for surgery. Thus, the correlation between the diagnostic utility of the 3D approach and its plausible practice for surgery purposes was the object of the final study. The starting point was suggested by veterinary literature that reports in few papers the development and application of surgical devices used to perform assisted-correction of bone deformities. These surgical tools are designed through 3D geometrical models and act both as precise intraoperative localizers of osteotomy corrective landmarks and surgical saw guides. Three-dimensional assessment of a bone conformation may improve the understanding and evaluation of bone deformities and occurring joints malalignment. In this sense, the localization of the CORA as well as the accuracy of the orientation of the osteotomy-cutting plane may be significantly upgraded through a 3D approach.
La tesi di dottorato presentata è stata concepita nell’ambito di un più ampio progetto che comprende molteplici studi tra loro intrinsecamente correlati. L’obiettivo principale del lavoro consiste nella descrizione delle basi teoriche, sviluppo nonchè applicazione pratica nel campo della diagnostica per immagine e chirurgia di un nuovo protocollo 3D utilizzato per la misurazione di angoli nel femore del cane. Lo scopo successivo è stato quello di descrivere il valore traslazionale della procedura analitica qui presentata. Il primo passo dell’intera ricerca è rappresentato dalla validazione della metodologia. Un nuovo algoritmo sviluppato consente, per mezzo di un CAD software di comune utilizzo (Rhinoceros), di eseguire la computazione di angoli in 3D. Il secondo step ha previsto la verifica della ripetibilità e della riproducibilità di tale metodica che è stata comparata con quelle più comuni effettuate con radiografia e Tac. Infine, con l’ultimo studio abbiamo traslato le basi teoriche in applicazione chirurgica andando a creare, per mezzo dell’algoritmo elaborato, delle dime chirurgiche. Questi strumenti intra-operatori sono molto utili durante la chirurgia per le osteotomie correttive in quanto si accoppiano perfettamente nel punto di deformità e consentono di guidare l’osteotomia dell’osso.

This thesis contains different studies on the effects of the rapid palatal expansion.The purpose of this thesis is to investigate some of the effects of palatal expansion which are still unaddressed in literature. The first part of the thesis, after a brief introduction to the transverse maxillary contraction and palatal expansion, will outline the results of clinical trials that relate to the non-orthodontic effects that palatal expansion may have on: cervical vertebrae, posture and upper airways.The second part will show the first results, from an orthodontical point of view, of a multicentric randomized clinical trial designed to analyze the possible different effects of palatal expander anchored on deciduous or permanent teeth.

Investigating the organization of production systems can reveal much about a society, in particular how resources and labor were allocated, and the influence that economic, political, social, and ceremonial institutions had on the production process. Interpreting the nature of specialized production is useful for understanding how production was organized. In turn, the degree of standardization exhibited by the goods being produced is used to determine the nature of specialization. While archaeological research regarding specialized production has expanded over time to incorporate a wide range of societies, such research is often focused on complex societies. The research presented here focuses on the small-scale, or non-stratified, community that once inhabited the Kolomoki site, a Middle to Late Woodland period site in Early county, Georgia. This thesis utilizes a three-dimensional laser scanner to document Weeden Island pottery from Kolomoki. The digital images created by the scanner were used to measure incising and punctation marks. The measurements were then analyzed in order to determine the extent of standardization among the decorative attributes. Results suggest that standardization varies among different subsamples of pottery. However, the overall degree of standardization is relatively low, thus suggesting that specialized production may not have existed, or was very limited, at Kolomoki. Despite the limited extent of standardization among the decorative attributes, the results of this research, especially in conjunction with previous research, suggest that some pottery may have been afforded special attention during the production process. In particular, pottery from mound proveniences, and socially valued goods, notably sacred and prestige items, demonstrate higher degrees of standardization. This leads to the conclusion that the production of Weeden Island pottery was likely influenced by ritual and ceremonial activity within the Kolomoki community. This thesis contributes to a greater understanding of specialization in non-stratified Woodland period societies in the southeastern United States.

The aim of this thesis is to scan the part of the interior and exterior of the Faculty of Electrical Engineering and Communication building using the FARO Focus3D X 130 scanner, and the creation of a 3D model in the WGS 84 system. Subsequently, methods, status and utilization research of this technology and point cloud processing software is provided. The collected data are processed in the SCENE. Three-dimensional model is designed using the Pointfuse and Microstation V8i programs. In the end, the registration accuracy of the scans and the resulting 3D model accuracy are evaluated.

A method to create three-dimensional images is demonstrated by using colonoscopy in magnetic resonance imaging (MRI) as an application. A stack of twodimensional images is acquired by moving an internal surface coil along the structure of interest and using the images as the basis for creating the three-dimensional image.. Spatial information about the individual two-dimensional images is required in order to t' correctly build the three-dimensional image: Specialised tracking coils for the colonoscope have been constructed to provide the location and orientation needed for each image acquired from an imaging coil that can be mounted on the colonoscope. The tracking coils are used for both acquiring positional information and for defining the location for scanning. Hence, as the colonoscope moves in the' body, the scan plane will change accordingly. Images and tracking data were collected from experiments using an MRI scanner, cylindrical phantoms to mimic the colorectum, and a colonoscope coil mounted on a mock colonoscope that also housed the tracking coils. Image processing techniques were used to filter each image and to correct for the falloff of the signal as the distance increased from the imaging coil. Bilateral filtering was based on noise estimates determined in each image. In combining the images and by using surface rendering, the creation of a threedimensional model that has a superior signal to noise ratio at the clinically relevant depth compared to an external coil is demonstrated.

A computer graphics workstation was developed to geometrically plan scanned focussed ultrasound hyperthermia treatments, and is currently in clinical use at the Arizona Health Sciences Center. The workstation allows the user to base the treatment plan on any set of hard copy images of the patient's treatment anatomy by using a frame grabber to import these images into the workstation. Anatomical structures are outlined by the user, and a three dimensional image is reconstructed using these outlines. A geometric outline of the ultrasound power deposition field is then inserted into the reconstructed patient anatomy, along with thermocouple junction locations. The use of a custom foam mold and fiducial marker system enables the location of the anatomical features to be determined in the treatment system's coordinates. A scan size and orientation that sufficiently sonicates the treatment volume can then be determined in an interactive three dimensional environment.

Title: Investigating clinically relevant methods of assessing the quality of three-dimensional surface scan data in dentistry Motivation: Having an awareness of the quality of three-dimensional (3D) scan data produced by a dental scanner can affect the clinician’s treatment plan, and potentially whether they choose to invest in a 3D scanner for clinical use. Assessing the quality of 3D scan data can therefore be of great value both to practitioners and scanner manufacturers. Statement of problem: Assessing the quality of 3D data is a challenge; assessing the quality of 3D data for clinical use is even more so. As a result, there is no standardised method of assessing, or reporting, the quality of 3D data within the field of dentistry. This research aimed to investigate methods of assessing the trueness and precision of scanners with clinical application in mind. Method and summary of publications: This research resulted in four publications. All data collection was undertaken in vitro. Digital processing, measurements and analyses were all performed digitally, in most cases using automated methods. Chapter 2 compares full arch edentulous scans produced by six intraoral scanners [IOS], with focus on identifying full arch error which may not be identified if analysed using commonly used methods such as measuring the mean distance deviation between a scan-pair. The proposed method suggests reporting the unsigned distance of the median value of the upper 1% most deviating aspect of a repeated scan. Chapter 3 investigates three methods of analysing scan data produced by two IOSs, applying the upper-bound method presented in the previous chapter in a more approachable manner, by reporting the percentage of a scan deviating beyond 0.1mm. This paper also presents the use of a virtual key point method, by which topologically similar key points can be robustly identified across differing meshes. The virtual key point method is further investigated in Chapter 4, in which the accuracy of the virtual occlusion of an IOS is investigated. By using virtual key points, the proportion of error produced by the arch scan and the proportion of error which is introduced during the occlusion stage are identified. Lastly, in Chapter 5 the key point method is used to investigate the precision of physical interocclusal records and the difference in precision between virtual articulation of dental models using un-clamped, scanned bite records, and traditional, manual articulation done by an experienced technician. Having determined the accuracy with which an IOS can record occlusion in the previous chapter, we use the same scanner to digitally record the technician’s manual articulations and, from there, identify the portion of error which was introduced by the manual articulation. Results: Chapter 2 finds that the upper-bound method may provide a clinically useful metric with which to gain an insight into the precision of full arch scans produced using different IOSs. The results indicate that three of the six scanners investigated would likely produce scans appropriate for clinical use where the full arch is required, while the latter three produced errors deviating beyond 0.3mm, hence proving to be unlikely to be appropriate for clinical use. Chapter 3 concludes that the Primescan produces significantly truer scans than the Omnicam, regardless of the method used to analyse the scan data. Furthermore the ‘standard’ analysis method might incorrectly infer that Omnicam produced clinically acceptable full arch scans. The proposed novel methods, measuring the intermolar-width and proportion beyond 0.1mm, may give a clinically relevant insight into the quality of scan data. These novel analyses reveal clinically unacceptable limitations for Omnicam. Our findings in Chapter 4 conclude that while the virtual bite records were relatively precise ((never deviating beyond 0.022mm) the error produced during the creation of the full arch scan negatively impacts the virtual occlusion. Lastly, Chapter 5 indicates that the digital articulation method using un-clamped, scanned bite records is significantly more precise than the traditional articulation method when considering precision (or lack of dislocation) along the anteroposterior axis. Discussion: All papers, with the exception of Chapter 5, investigate aspects of IOSs ability to accurately record full arch scans. All investigations presented are in vitro; as a result one may assume the quality of in vivo scan data will be worse than the findings reported herein. Chapter 3, which investigates the quality of full arch data produced by the Omnicam and Primescan scanners, highlights the importance of using the appropriate measurement method during investigation, as seen in Figure 3:2. Chapters 4 and 5 highlight the variable nature of digital methods, with the IOS virtual occlusion feature being negatively affected by error produced in the full arch scan, making the method less likely to be clinically reliable. Whereas the virtual method in Chapter 5 indicates that virtual articulation, using a high quality, clamp-less laboratory scanner is likely to reproduce articulation more precisely than traditional, physical methods. Conclusion: This thesis concludes that efforts to gain a clinically relevant insight into the quality of scan data are challenging. It finds finds that there is no one-size-fits-all when assessing 3D data in a clinically relevant manner but suggests some newer methods that go some way to addressing this. Standard surface comparison methods, borrowed from Engineering and used extensively in dental research, almost invariably produce overly optimistic results. Given that dental audiences are generally less well versed in mathematical 3D analysis, there is a real risk that clinical applicability of some digital techniques may be advocated in error. The findings also show that the quality of 3D data within digital dentistry varies widely. A paradigm shift from digital dentistry being considered as multiple methods all producing data and clinical work of similar quality, to digital dentistry being considered an umbrella term covering a spectrum of workflows, all of highly varying quality, is needed.

Este trabalho tem como objetivo principal desenvolver um método para obtenção de parâmetros antropométricos através de um digitalizador tridimensional de baixo custo. A fundamentação teórica da presente pesquisa abrange temas relacionados ao processo de Design, produtos personalizados e de tecnologia assistiva, além da relação entre os parâmetros antropométricos e o projeto de produto. Assim, foram investigados os métodos utilizados para o levantamento dos parâmetros antropométricos pelo processo direto de medição e o respectivo estado da arte. Ainda, foram investigados os métodos utilizados para o levantamento de parâmetros antropométricos lineares por digitalizadores tridimensionais. A metodologia da pesquisa consiste em cinco etapas: pesquisa bibliográfica, coleta e análise dos dados antropométricos pelo método direto e o desenvolvimento do método indireto de obtenção de medidas antropométricas, comparação e análise dos dados obtidos, discussão dos resultados e a finalização da pesquisa. O processo de digitalização utilizado está baseado em um dispositivo de baixo custo, o Microsoft Kinect e no software kscan3D. Para o levantamento antropométrico a partir do modelo tridimensional, é utilizado o software Autodesk 3D Studio Max. Através da comparação e avaliação entre os dados obtidos pelo método direto e indireto, foi possível verificar a compatibilidade dos dados e, assim, validar o método desenvolvido. Como resultado foi proposto um método para realização do levantamento de parâmetros antropométricos utilizando um digitalizador 3D de baixo custo. A pesquisa apresenta recomendações e restrições para a geração do modelo tridimensional, de forma a se obter uma malha com precisão satisfatória. É apresentado um fluxograma para orientar a aplicação do método desenvolvido no processo de Design bem como um quadro-resumo contendo diretrizes para esta aplicação. O método desenvolvido obteve 97,96% de compatibilidade nos resultados das variáveis mensuradas em relação ao método direto. Estes resultados foram obtidos com um tempo de exposição do indivíduo de apenas 3 minutos e 28 segundos, muito inferior ao tempo necessário no método direto, que foi de 1 hora e 12 minutos, o que demonstra uma das principais contribuições do método proposto.
The aim of this paper is to develop a method for obtaining anthropometric parameters using a low cost three-dimensional digitizer. The theoretical foundation of this research covers topics related to the design process, personalized products and assistive technology. It also considers the relationship between anthropometric parameters and product design. Thus, we investigated the methods used in the analysis of anthropometric parameters through direct process measurement and its state of the art. Moreover, it was investigated the methods used for collect anthropometric parameters through linear three-dimensional scanners. The research methodology is divided in five steps: literature review; collection and analysis of anthropometric data using the direct method and also the development of the indirect method for obtaining anthropometric measurements; comparison and data analysis; discussion of results and the completion of the research. The digitization process developed it is based on Microsoft Kinect, a low-cost device, and also on the software kscan3D. For the anthropometric collection from the three-dimensional model is used Autodesk 3D Studio Max. Through the comparison and evaluation of the data obtained by the direct and the indirect methods, it was possible to verify the compatibility of the data and thus validate the developed method. Therefore, it was proposed a method for collecting anthropometric parameters using a low-cost 3D scanner. This research presents requirements and constraints for generate the threedimensional model in order to obtain a mesh with satisfactory precision. It is presented a flowchart to guide the implementation of the developed method in the design process as well as a summary table containing guidelines for this application. The developed method achieved 97.96% of compatibility considering the results of the measured variables in relation to the direct method. These results were obtained with an exposure time of the individual of only 3 minutes and 28 seconds, which is less than the time required in the direct method – 1 hour and 12 minutes. This demonstrates one major contribution of the developed method.

Forensic facial reconstruction can assist identification by reconstructing a face of the unknown person with the aim of its recognition by his/her family or friends. In the facial reconstruction approach adopted in this study, a 3D average face template was digitally warped onto a 3D scanned skull image. This study was carried out entirely on an Egyptian population, and was the first of its kind. Aims: This study aimed to demonstrate that 3D facial reconstructions using the novel methodology described could show significant resemblance to the faces corresponding to the persons in question when they were alive. Moreover, using techniques previously validated for facial reconstruction, the aim was to compare them to the method developed, and to assess approaches used to determine the accuracy of 3D facial reconstructions. Methods: Initially, a pilot study was conducted using a database of laser scanned skulls and faces. The faces were reconstructed using an average facial template generated by merging a number of faces of similar population, sex, and age. The applicability, as well as the main components of the facial reconstruction method, the single and average facial templates, and the facial soft tissue thickness measurements, were investigated. Furthermore, in the main study, the faces of computed tomography (CT) scanned heads of an Egyptian population were reconstructed using average facial templates. The accuracy of the reconstructed faces was assessed subjectively by face pool, and face resemblance tests, and objectively by measuring the surface distances between the real and reconstructed faces. In addition, a number of novel subjective and objective assessment methods were developed. These included assessment of individual facial regions using subjective resemblance scores, and objective surface distance comparisons. A new objective method, craniofacial anthropometry, was developed by taking and comparing direct measurements from the skull, and comparing the measurements from the real and reconstructed faces. The studied cases were ranked according to all subjective, and objective, tests, and statistically correlated. Results and Conclusions: The average facial templates showed a higher identification rate than the single face templates. The approach of facial reconstruction used in this thesis showed a comparable accuracy to many other facial reconstruction methods, yet was superior in terms of its applicability, transferability, and ease of use. In the face pool tests, the younger assessors were able to correctly identify the reconstructed faces better than older assessors. Furthermore, the identification rate by the forensic anthropology experts was higher than the non-experts. The former group showed the highest agreement between the observers in giving the resemblance scores. Although there was a significant rank correlation between the subjective and objective assessment tests, the subjective tests are influenced by the assessors' subjective characteristics (e.g., age, professional experience), thus making objective assessment more reliable. However, in situations where subjective tests are used, it is better to use the face resemblance tests and consult forensic anthropologists. Also, Craniofacial Anthropometry, particularly the craniofacial angles, can successfully indicate the accuracy of the facial reconstructions. Importantly, this study shows that certain facial regions, particularly the cheek and the jaw, are more reliable than other areas in the subjective and objective assessment of the facial reconstruction.

碩士
國立中央大學
土木工程研究所
93
Airborne three-line-scanner images have the merits of high spatial and spectral resolutions and excellent converging geometry. Thus, the images have become an important data source in environmental remote sensing, GIS and three dimensional positioning. The three-line-scanner acquires three different direction images, which have plenty of overlapped area in flying. Thus, the bundle adjustment is selected to calculate the dynamic orientation parameters. The additional parameters will be included in the adjustment. The orientation parameters are modeled using low-order polynomials with respect to time by employing GCPs and tie points. The process might contain local systematic errors for the data with high dynamics, thus, a least squares filtering that performs orbit collocation is included. In this investigation, Level 1 images that have been preliminarily rectified using GPS and INS data are investigated for 3-D positioning. In this investigation four major steps are included: (1) definition of image coordinates for three-look images including additional parameters, (2) calculation of orientation parameters using bundle adjustment, (3) collocation of the orientation parameters by least squares filtering, and (4) accuracy validation. The test data include six trips. In bundle adjustment, the tie points are selected for each of the three-look images that appear in the overlapped area of strips. The experimental results indicate that the bundle adjustment could reach higher accuracy when the cross trips are employed.

碩士
國立成功大學
機械工程學系
102
Three-dimensional raster scanner is a challenging instrument. To complete this machine needs many theories, such as stereovision, camera calibration, structured light techniques, positioning registration and skill of software development. Purpose of this study is to develop a three-dimensional raster scanner, which has double scanning range compared to normal dental scanner. This study employs stereo visualization theory with dual cameras, in order to obtain two camera's parameters by Tsai's calibration method. After camera calibration, we use a projector to provide the light source with a computer generated structure gray image. According to the position of the projector, range of scanning domain were amplified. And then, we increase the number of projection image to avoid deviation points. In order to gain entire cloud points for further analysis, we used TrICP algorithm to register the coordinate of point cloud from several scan positions. We also use a calibrated block to accelerate the speed of registration processes by saving each transition matrix for every positions. Finally, tests of a few simple cases reveal that the calibration accuracy is 0.026 ± 0.02mm, the single-scan accuracy is 0.158 ± 0.033mm, and the multiple scans accuracy is 0.225 ± 0.150mm.

碩士
國立中正大學
機械工程系研究所
106
The study integrates structure light system with six-axis manipulator to examine the algorithm performance in different situation. Generally, based on the CAD model, flat patch recursive algorithm is used to calculate the scanning gestures for robot equipped with a 3D scanner. However, the required number of gestures calculated by flat patch recursive algorithm is significant for CAD model with huge number of meshes. To improve the efficiency of existing scanning gesture searching algorithm, this study expanded the concept of region growing which is commonly used in image segmentation to three-dimensional mesh model to calculate the potential scanning gestures. In this study, seven different objects with CAD models have been used to compare performance between the proposed algorithm and flat patch recursive algorithm. The experimental result shows that although the scanning area is a little bit less than the existing algorithm, the number of scanning gesture of proposed algorithm is significantly reduced and thus prevents accumulating error resulted from multiple view registration. In addition, the computation time of proposed algorithm is less than the one of flat patch recursive algorithm.

碩士
國立中正大學
機械工程系研究所
104
The research aims to develop a method about structured light codec techniques. In the last few years, gray code is commonly used for structured-light 3D scanner measuring which is accurate but time consuming. Therefore, this paper takes advantage of color image with three channels to reduce the number of projected images in the same resolution, improving the scanning efficiency. However, the depth accuracy reconstructed by color code is not as good as gray code. In order to improve the accuracy of color code, this paper propose an idea that offset the pattern a stripe width, then calculate the intersection of two image's intensity value curve, it's not only able to estimate the accurate boundaries but also can reduce the crosstalk effects between different channels. In addition to that, we combine boundary inheritance methods to eliminate the error of the consistency among the same boundaries of different layers in pattern hierarchy. According to the experimental results prove that the proposed method improves the decoding image, enhance the quality of color coded reconstruction, and reduce the number of projected images without reducing accuracy.

A prototype rapid, high precision fan beam optical computed tomography (OptCT) scanner for three-dimensional polymer gel dosimetry of complex radiotherapy protocols has been developed. This study documents the design. construction and characterization of the system, as well as preliminary reconstructed optical attenuation images and dosimetric verification experiments. The principal goal in scanner design and implementation was to satisfy the Radiotherapy Accuracy and Precision (RTAP) criteria consisting of a spatial resolution of 1 x 1 x 1 mm3, an imaging time of 60 minutes, a dose accuracy within 3% and a precision within 1%. The scanner, which employs a sixty degree fan beam of 543 nm laser light to scan irradiated polymer gel samples up to 19 cm in cross-sectional diameter. has several defining attributes. Data acquisition for a single slice through a dosimeter is achieved in two minutes, using one signal acquisition per CT projection angle over a total of 360 projections. The effects of scatter and refraction of visible light are minimized by using the unique radial design of the matching medium tank, the concentric arrangement of a prototype, computer numerical control (CNC)-machined collimator and five Hamamatsu photodiode detector arrays for light detection. The novel tertiary collimation eliminates scattered light by 13% and improves reconstructed image contrast-to-noise ratio. Other characteristics of the scanner include: a laser power output variation of only 0.7%:, signal-to-noise ratio (SNR.) for calibration projections of up to 294:1, SNR for transmission projections through an irradiated polymer gel dosimeter of up to 161:1, a large absorbance dynamic range extending from 0.1 to 1.7 absorbance units and a spatial resolution of 0.25 mm2 in the axial plane of the scan¬ning geometry and 0.8 mm along the longitudinal z-axis of the scan plane. Images of optical attenuation coefficients and concomitant dose maps extracted from irradi¬ated, normoxic N--isopropylacylamide (NIPAM) polymer gels were used to investigate the potential of the system for dosimetric verification. Three different NIPAM gel irradiation experiments were performed and the resultant OptCT dose distributions were compared to the Eclipse® (Varian Medical Systems. Palo Alto. CA.) treatment planning system model. While the fan beam OptCT scanner provides promising ini¬tial images of reconstructed optical attenuation coefficients, its dosimetric accuracy compared to Eclipse - nominally 7% in low dose gradient regions and 5% on the field edges - constitutes the most significant area for future refinement.

The current state of a prototype fan-beam optical computed tomography scanner for three-dimensional radiation dosimetry has been presented. The system uses a helium-neon laser and a line-generating lens for fan-beam creation. Five photodiode arrays form an approximate arc detector array of 320-elements. Two options of physical collimators provide two levels of scatter-rejection: single-slot (SS) and multi-hole (MH). A pair of linear polarizers has been introduced as a means of light intensity modulation. This work examined: (i) the characterization of system components, (ii) data acquisition & imaging protocols, and (iii) the scanning of an nPAG dosimeter. (i): The polarizer-pair method of light intensity modulation has been calibrated and the polarization sensitivity of the detector array was evaluated. The relationship between detected values and both light intensity and photodiode integration time was examined. This examination indicated the need for an offset correction to treat all data acquired by the system. Data corruption near the edges of each photodiode array was found to cause ring artefacts in image reconstructions. Two methods of extending the dynamic range of the system---via integration time and light intensity---were presented. The use of master absorbent solutions and spectrophotometric data allowed for the preparation of absorption-based and scatter-based samples of known opacities. This ability allowed for the evaluation of the relative scatter-rejection capabilities of the system's two collimators. The MH collimator accurately measured highly-attenuating solutions of both absorption-based and scatter-based agents. The SS collimator experienced some contamination by scattered light with absorption-based agents, and significant contamination with scatter-based agents. Also, using the SS collimator, a `spiking' artefact was observed in highly-attenuating samples of both solution types. (ii): A change in imaging protocol has been described that greatly reduces ring artefacts that plagued the system previously. Scanning parameters related to the reference scan (Io) and data acquisition were evaluated with respect to image noise. Variations in flask imperfections were found to be a significant source of noise. (iii): An nPAG dosimeter was prepared, planned for, irradiated, and imaged using the fan-beam system. In addition to ring artefacts caused by data-corruption, refractive inhomogeneities and particulates in the gelatin were found to cause errors in image reconstructions. Otherwise, contour and percent depth dose comparisons between measured and expected values showed good agreement. Findings have indicated that significant imaging gains may be achieved by performing pre-irradiation and post-irradiation scans of dosimeters.

Clinical radiotherapy treatments using linear accelerator (linac) generated megavoltage xray beams are planned using computer models that calculate patient specific three dimensional (3D) radiation dose distributions. Treatment planning system (TPS) calculated doses are evaluated by clinicians to ensure suitable dose coverage of targeted tumours and the avoidance of excessive doses to normal tissues. The accuracy of the TPS must be validated by measurement to ensure correct patient treatments. Traditional radiotherapy dosimeters do not measure dose entirely in 3D. They effectively ‘spot check’ accuracy at discrete points or planes, without the ability to fully visualise measured dose distributions in true 3D. True 3D dosimetry systems have been a subject of research for more than 3 decades. Gel dosimetry with optical computed tomography (CT) scanning using visible light wavelengths has been under investigation and development for much of this time. A lack of clinical uptake of the systems developed to date suggests that there are deficiencies or unappealing aspects, such as optical CT scanner maintenance and reliance upon optical expertise. Dosimetric accuracy of these systems also requires improvement, closer to accepted clinical dosimeters. In this work it was postulated that an optical CT scanner could be developed that is more efficient, practical and accurate than those demonstrated previously. This would address key aspects relating to clinical appeal. A specific application of stereotactic radiosurgery was targeted, where small dose distributions are delivered with high spatial accuracy to cranial tumours. Improvements in the practicality and efficiency of optical CT scanning were initially sought by elimination of the need for a refractive index (RI) matching fluid bath for scanning gel dosimeter samples. Optical simulations were used to investigate and identify suitable optical geometry that would enable fluid-less scanning for tomographic reconstruction. A prototype fluid-less optical CT scanner was constructed and the proof of concept was demonstrated using ferrous xylenol orange gel (FXG). The next phase of work was to develop the dosimetry system further, striving for dosimetric accuracy. The properties of the FXG dosimeter were studied by characterising the dose response, dose development, ion diffusion and thermochromism. The scanner was refined by addressing imaging artefacts, the addition of a reference detector and the development of a cuvette based dose calibration procedure. Standard procedures for gel manufacturing and handling, and for optical CT operation were developed to improve reproducibility of results. The system’s performance was assessed and its utility was demonstrated in the clinical application of linac radiosurgery and was also extended to brachytherapy 192Ir source verifications. Further improvements of system practicality and measurement quality were proposed by the concept of dual wavelength scanning. A second laser of a different wavelength could provide reference scan data instead of pre-irradiation scans. This would give a single scan procedure for greater practicality and could improve measurement quality by avoiding scan to scan artefacts. Dual wavelength feasibility was first investigated by revisiting optical simulations and the development of a design incorporating a second laser. Through the addition of the second wavelength further insights were gained into optical artefacts and image quality improvements were realised. An alternative calibration method using a reconstructed test pattern was compared to the cuvette method and resulted in improvements of calibration accuracy for dual wavelength scanning. The dual wavelength scanner dosimetry system was tested and benchmarked using a range of test irradiations, with comparison to reference dosimeters. This culminated in a true 3D dosimetry solution for radiotherapy dose verifications with accuracy of the order of 1 %, together with practical and efficient optical readout for clinical use.
Thesis (Ph.D.) (Research by Publication) -- University of Adelaide, School of Physical Sciences, 2018

Thesis (M.Sc.(Sports Medicine))--University of the Witwatersrand, Faculty of Health Sciences, 2014.
Within the context of sports medicine, biomechanical corrective custom foot orthoses are utilised as a treatment intervention to correct pathological gait disorders. In order to manufacture such corrective devices a replicate model of the patients’ foot needs to be obtained. This study aimed to assess both the inter-rater reliability and the intra-rater repeatability of a semi weight bearing foot modelling technique employing a three dimensional white light surface foot scanner. The sample cohort included twenty healthy male and female subjects with ages ranging from 18-70 years. Six qualified Podiatrists were utilised as raters to perform the foot placements on the white light scanner. All raters and participants were given a ten minute training session to familiarise them with the equipment and scanning procedure. The subjects’ left foot was marked and raters positioned and scanned the left foot three times. Digital foot parameter measurements of medial arch height, forefoot width, foot length and rearfoot width were recorded and analysed. The results from this study showed high inter-rater reliability with intraclass correlation coefficients ranging from 0.997 to 1.00 with the specified foot parameter measurements. Intra-rater repeatability of the same specified foot parameter measurements demonstrated good repeatability with Pearson coefficients of correlation values ranging from 0.973 to 0.997. The assessment of the reliability of computerised digital white light scanning as an integral first step in the manufacture of custom foot orthoses has a direct effect on Podiatric practice and the outcomes of patient treatments with this therapeutic modality.

Introdução: Após a extração dentária tem início o processo de remodelação dos tecidos ósseos e tecidos moles, provocando alterações morfológicas nos mesmos. A colocação de implantes dentários imediatos com a aplicação de substitutos ósseos e matrizes de colagénio reabsorvíveis tende a minimizar a reabsorção que tem lugar nos tecidos peri-implantares. Apesar desta vantagem, é difícil prever com precisão o que acontece após esta sequência de tratamento, uma vez que são envolvidos tanto tecidos ósseos como tecidos moles da região peri-implantar. Objetivos: Analisar as alterações volumétricas que ocorrem nos tecidos ósseos e tecidos moles peri-implantares, assim como verificar quais as características ósseas iniciais que desempenham um papel preponderante nas alterações que os tecidos peri-implantares sofrem após a colocação de implantes imediatos na zona estética maxilar durante o primeiro ano de tratamento. Materiais e Métodos: Vinte e seis pacientes tratados com implantes dentários unitários após extração dentária foram incluídos neste estudo. Uma tomografia computorizada por feixe cónico (CBCT) efetuada previamente à extração dentária confirmou a integridade da cortical óssea vestibular. O espaço existente entre o implante e a parede óssea alveolar vestibular foi medido para futura análise (BID) e posteriormente preenchido por um substituto ósseo. Impressões digitais foram efetuadas antes da extração dentária (T0) e a um (T1), quatro (T2) e doze meses (T3) após colocação do implante dentário. Os ficheiros de estereolitografia (STL) obtidos foram sobrepostos através de um programa informático, permitindo realizar uma análise volumétrica tridimensional dos tecidos peri-implantares, calculando diferentes variáveis como a espessura, área e volume, que expressaram as alterações entre T0 e os seguintes controlos pós-operatórios. A análise da imagem de CBCT permitiu obter diferentes parâmetros pré (T0) e pós-operatórios (T3) como a espessura da cortical alveolar vestibular (BT), a altura da cortical vestibular (BH), a altura da cortical palatina (PH) e a distância entre as mesmas (BPD). Resultados: Através da análise linear observou-se uma variação total de espessura em T1, T2 e T3 de -0,45±0,51mm, -0,46±0,39 e -0,52±0,38, respetivamente. A variação volumétrica da face vestibular em T1, T2 e T3 foi de -7,20±6,62%, -7,82±6,86% e -9,52±7,44%, respetivamente. Verificou-se também uma alteração do parâmetro BPD em T3 de -1,50±1,09mm e, após um ano de observação, indivíduos com BT ≤1mm exibiram maior variação de espessura vestibular (-0,48±0,28mm), comparativamente aos pacientes com BT>1mm (-0,17± 0,11mm) (p=0,049). Uma regressão linear múltipla determinou os parâmetros BT e BPDT0 como determinantes na evolução das variáveis de espessura e volume ao fim de quatro meses, não sendo encontrada significância estatística no que concerne à influência de BID. Uma correlação linear positiva foi observada entre as variações de BPD (T0-T3) e as alterações totais de espessura e volume verificadas em T1, T2 e T3. Conclusão: A colocação de implantes imediatos após a extração dentária é um tratamento previsível com uma taxa de sucesso comparável ás técnicas convencionais de colocação de implantes em zonas alveolares cicatrizadas, apesar de não impedir na totalidade o processo reabsortivo do osso alveolar associado à extração do dente. A espessura da cortical vestibular influencia significativamente as alterações de espessura e volume que ocorrem nos tecidos peri-implantares em tratamentos com implantes imediatos pós-extracionais do sector anterior maxilar.
Introduction: After a single-tooth extraction, remodelling processes are initiated and morphological changes occur in the alveolar bone. Immediate implant placement associated with the use of bone substitutes and a collagen matrix seems to reduce the amount of resorption at peri-implant areas. Despite the advantages with the use of these techniques, it is difficult to predict with precision what is going to happen after immediate implant placement, since it involves hard and soft tissue volume changes. Aim: To evaluate the volumetric changes in hard and soft peri-implant tissues after flapless immediate implant placement in the aesthetic zone during the first year of treatment as well as determinate which initial alveolar bone features may play a crucial role on peri-implant tissues alterations. Materials and Methods: Twenty-six patients treated with single-tooth maxillary implants after flapless tooth extraction between 15 to 25, were included in this study. The horizontal implant/bone gap was measured for further analysis (BID) and filled with a xenograft bone substitute. Digital impressions were taken prior to extractions (T0), one month (T1), four months (T2) and 12 months (T3) after implant insertion. The obtained Standard Tessellation Language (STL) files were superimposed with a computer software allowing to create a colour map that quantitatively analysed the three-dimensional variations occurred in the intervened areas and adjacent tissues. Variables related to thickness, area and volume representing the changes between T0 and the different postoperative follow-ups were computed. A CBCT exam allowed to access pre (T0) and postoperative (T3) parameters such as buccal bone thickness (BT), buccal plate height (BH), palatal plate height (PH) and the distance between them (BPD). XIV Results: The linear measurements showed a total mean change in thickness at T1, T2 and T3 of -0,45±0,51mm, -0,46±0,39 and -0,52±0,38, respectively. Buccal volume variation at T1, T2 and T3 was -7,20±6,62%, -7,82±6,86% and -9,52±7,44%, respectively. A mean variation on BPD of -1,50±1,09mm was observed at T3 and after 1-year of treatment subjects with BT≤1mm exhibited a significantly increased buccal thickness variation (-0,48±0,28mm) than patients with BT>1mm (-0.17± 0,11mm) (p=0,049). A multi-variate regression analysis proved a statistical significant influence of BT and BPDT0 on thickness and volume variations after 4 months, whereas no statistical significance was found on BID effect. A positive linear correlation was detected between BPD variations (T0-T3) and total thickness and volume alterations at T1, T2 and T3. Conclusion: After the first year of treatment following flapless single immediate implant placement in maxilla, peri-implant tissues showed a continuous alterations resulting in a thickness change that occurred mainly in the first month and tended to be stable after the fourth month. Thickness and volume variations were significantly influenced by initial buccal bone thickness.