A morphological study of retromolar foramen and retromolar canal of modern and medieval population

Background: Retromolar foramen (RMF) is small external orifice of the retromolar canal (RMC), located in the retromolar region of the mandible. Knowledge about the location of the RMF and the route of the RMC within the mandible is significant for clinical practice due to a high risk of injury during oral and craniomaxillofacial surgery. Materials and methods: In this study, the authors analysed 100 cone-beam computed tomography (CBCT) scans of the modern people’s retromolar region and 26 scans of samples from the medieval population. Additionally, 74 retromolar regions of the medieval people were examined macroscopically. Results: The statistical analysis showed a correlation between the frequency of RMC occurrence and bone thickness on the medial surface of the RMC. Also it was proven that the results of the RMF identification based on macroscopic examination of the bone may be falsely negative or positive and it is caused by destruction caused by resting in soil. Conclusions: Thus, CBCT is the best tool for RMF and RMC identification

Konik ışınlı bilgisayarlı tomografi kullanılarak mandibular kanal varyasyonlarının ve temporal kret kanallarının değerlendirilmesi

Amaç: Bu çalışmanın amacı konik ışınlı bilgisayarlı tomografi (KIBT) kullanılarak mandibular kanal varyasyonlarının ve temporal kret kanallarının (TKK) değerlendirilmesidir.Gereç ve Yöntemler: Çalışmamızda Aydın Adnan Menderes Üniversitesi, Diş Hekimliği Fakültesi, Ağız, Diş ve Çene Radyolojisi Anabilim Dalı’nda implant planlaması, ortognatik cerrahi planlaması gibi nedenlerle KIBT alınmış olan 121 hastanın görüntüleri incelendi. Tüm KIBT görüntüleri, retrospektif olarak iki radyolog tarafından değerlendirildi. Görüntü analizi yazılımı kullanılarak oluşturulan kesitler üzerinde mandibular kanal varyasyonları ve TKK varlığı değerlendirildi.Bulgular: Çalışmamızda 121 hastanın 50'sinde (% 41.3) mandibular kanal varyasyonu tespit edildi. 71 (% 58.7) hastada ise varyasyon izlenmedi. Erkekler ve kadınlar arasında mandibular kanal varyasyonları açısından anlamlı fark yoktu. (p > 0.05) En sık görülen kanal tipi 24 hastada gözlenen dental tipti. 6 hastada retromolar tip kanal, 3 hastada anterior tip kanal, 2 hastada ise bukkal tip kanal gözlendi. 3’ü kadın, 2’si erkek olmak üzere 5 hastanın sağ mandibulasında TKK tespit edildi.Sonuç: Dental prosedürlerin planlanmasında mandibular kanal varyasyonları ve TKK’nın tanımlanması önem taşımaktadır. KIBT verileri bu varyasyonların varlığını doğrulamak için etkili bir görüntüleme yöntemidir.ANAHTAR KELİMELER Konik ışınlı bilgisayarlı tomografi, mandibular sinir, anatomik varyasyo

Anthropometric analysis of maxillofacial foramina in skulls of four human populations using electronic calliper and 3D laser scanning methods

This study was undertaken to identify the landmarks that would provide the most reliable and predictable indicators of the position of the supraorbital, infraorbital, mental and mandibular foramina in human skulls of Hokien, Hylam, Indian and British populations of ranging ages, which would provide clinicians with suitable modifications in technique to accommodate these variations. Measurements were taken using both electronic digital callipers and 3D laser scanning. Electronic digital calliper measurements were made to estimate how far each foramen was from specific anatomical landmarks on the skulls. An apparatus was developed to position the skulls securely so that the measurement points could be accurately identified, then an electronic digital calliper was used to measure the distance between the defined points. In addition, the same skulls were also scanned using a FastSCAN™ Polhemus Scorpion™ handheld laser scanner, and imported into 3D modelling software (FreeForm Modelling Plus™). This 3D software integrates a PHANYOM™ desktop arm and a haptic force feedback device that provides the user with a sense of touch. Accordingly, with the “Ruler” tool, the measurements between various foramina and defined anatomical landmarks were measured. Measurements made by electronic digital calliper were compared statistically with those made using the 3D scanning method, and overall there was good correlation between the two, indicating that 3D scanning could be used as an alternative method. With regard to age changes in the skulls, the ages of the Hokien and Hylam groups were known, having been recorded from death records, but the Indian and British skulls were not of known age. In a preliminary study the known age skulls were used to validate the methods of Miles (1962) and Brothwell (1981) who aged skulls using tooth wear patterns. The decision was taken to use the Brothwell chart for the assessment of age in the Indian and British skulls in the main study. For each of the four population groups, intra-population comparisons of the measurements were made between right and left sides, and between skulls of young and old individuals, also inter-population comparisons between ipsilateral measurements were made. The correlation between the obtuseness of the mandibular angle and the ipsilateral measurement from the mental foramen to the posterior border of the mandible were made on both sides of the skulls of each population group. Non-significant differences were found between the measurements on right and left sides for the skulls of all populations. There were significant differences between some ipsilateral measurements but although there were statistically significant, they were not considered to be clinically significant. There were no significant differences between ipsilateral measurements with increasing age of the skulls. Also there were weak correlations between the obtuseness of the mandibular angle and the ipsilateral measurement from the mental foramen to the posterior border of the mandible on both sides of the skulls of each population group. There were good statistically agreements between the electronic digital calliper and 3D laser scanning measurements in all groups and the two methods may be used interchangeably. However 3D scanning is a digital process and therefore the scans could be accessed remotely, either across the internet or by CD

Human Teeth

This book provides information on nomenclature, tooth numbering systems, tooth morphology, and anatomy and stages of tooth formation. It continues with root canal morphology and anatomy of incisors, canines, premolars, and molars. External and internal anatomies of mandibular permanent incisors and maxillary permanent first molars are presented according to a literature review. Orofacial structures affecting tooth morphology are discussed in detail. The book ends with the evolution of dental implant shapes and today�s custom root analog implants

The Effects of Aging and Tooth Loss to the Microstructure of the Mandible in South Africans

Thesis (PhD (Anatomy))--University of Pretoria, 2022.The mandible plays a crucial role in many biological functions (especially mastication, swallowing and speech) and its efficiency to perform these functions depends on its intactness. Aging and tooth loss are biological processes that may compromise the normal functioning of the mandible by changing its morphology. While many studies address the macroscopic mandibular variations, there is a paucity regarding its microstructure. The aim was to investigate microstructural mandibular changes, with reference to the macrostructure, with advancing age and across various tooth loss patterns in South Africans. As the reasons why individuals are differently affected (extent, rate) by senescence or tooth loss are unclear, the influence of other biological factors (sex, ancestry) was also considered. Using micro-focus X-ray Computed Tomography (micro-CT) scans of 333 mandibles, external dimensions, and inner parameters, namely the cortical thickness (CtTh) and cortical density (approximated by histomorphometric parameters, BV/TV) were measured. To assess whether the mandible ages in the same way and rate as the rest of the skeleton, a comparison of mandibular and femoral cortical BV/TV, using a micro-CT subsample of 68 individuals, was included. A comprehensive assessment of the mandibular morphology and cortical microstructure of fully dentate individuals highlighted that the smaller the alveolar height is, the thicker and denser the cortical bone. An inner cortical asymmetry between basal, buccal, and lingual areas was described for CtTh, but was absent for BV/TV. Sexual dimorphism and ancestral variations were confirmed for the external distances and CtTh, but not for BV/TV. With tooth loss, a general decrease in external distances (aggravated by edentulism), CtTh and BV/TV was observed, except at the midline where the lingual CtTh increased with edentulism. Sexual dimorphism and ancestral variations of the external dimensions and CtTh were emphasised in edentulous mandibles. The cortical density decreased with aging, corroborating the general decline in bone mass of the skeleton, as noted in the femur. By contrasting the effects of tooth loss and aging, it was concluded that both external distances and CtTh were mainly influenced by tooth loss and not age, whereas the cortical bone density displayed an age-related decrease independent of tooth loss. To ascertain the applicability of the findings in a dental setting, where Cone-Beam Computed Tomography (CBCT) is commonly used, measurements were performed on 24 mandibles scanned by both CBCT and micro-CT (considered as the reference). The accuracy and repeatability of CBCT was confirmed for large-scale measurements, and CtTh in a lesser manner, whereas results were uncertain for BV/TV, revealing a distinct lack of reliability. In conclusion, this thesis inferred the precise role of aging and tooth loss, but also sex and ancestry, on the variations of the mandibular macro- and microstructure. Not only does knowledge and understanding of these changes have implications in dentistry fields, as cortical thickness and density are essential for many dental procedures; but also in biological anthropology, in which the microstructure of extant human mandibles gives valuable insights into intra- and interspecific variations (e.g., sexual dimorphism), or functional considerations (mastication, diet) of archaeological/fossil specimens.AnatomyPhD (Anatomy)Unrestricte

A Textbook of Advanced Oral and Maxillofacial Surgery

The scope of OMF surgery has expanded; encompassing treatment of diseases, disorders, defects and injuries of the head, face, jaws and oral cavity. This internationally-recognized specialty is evolving with advancements in technology and instrumentation. Specialists of this discipline treat patients with impacted teeth, facial pain, misaligned jaws, facial trauma, oral cancer, cysts and tumors; they also perform facial cosmetic surgery and place dental implants. The contents of this volume essentially complements the volume 1; with chapters that cover both basic and advanced concepts on complex topics in oral and maxillofacial surgery

PRELIMINARY FINDINGS OF A POTENZIATED PIEZOSURGERGICAL DEVICE AT THE RABBIT SKULL

The number of available ultrasonic osteotomes has remarkably increased. In vitro and in vivo studies have revealed differences between conventional osteotomes, such as rotating or sawing devices, and ultrasound-supported osteotomes (Piezosurgery®) regarding the micromorphology and roughness values of osteotomized bone surfaces. Objective: the present study compares the micro-morphologies and roughness values of osteotomized bone surfaces after the application of rotating and sawing devices, Piezosurgery Medical® and Piezosurgery Medical New Generation Powerful Handpiece. Methods: Fresh, standard-sized bony samples were taken from a rabbit skull using the following osteotomes: rotating and sawing devices, Piezosurgery Medical® and a Piezosurgery Medical New Generation Powerful Handpiece. The required duration of time for each osteotomy was recorded. Micromorphologies and roughness values to characterize the bone surfaces following the different osteotomy methods were described. The prepared surfaces were examined via light microscopy, environmental surface electron microscopy (ESEM), transmission electron microscopy (TEM), confocal laser scanning microscopy (CLSM) and atomic force microscopy. The selective cutting of mineralized tissues while preserving adjacent soft tissue (dura mater and nervous tissue) was studied. Bone necrosis of the osteotomy sites and the vitality of the osteocytes near the sectional plane were investigated, as well as the proportion of apoptosis or cell degeneration. Results and Conclusions: The potential positive effects on bone healing and reossification associated with different devices were evaluated and the comparative analysis among the different devices used was performed, in order to determine the best osteotomes to be employed during cranio-facial surgery

Development of procedures for the design, optimization and manufacturing of customized orthopaedic and trauma implants: Geometrical/anatomical modelling from 3D medical imaging

Tese de Doutoramento (Programa Doutoral em Engenharia Biomédica)The introduction of imaging techniques in 1970 is one of the most relevant historical milestones in modern medicine. Medical imaging techniques have dramatically changed our understanding of the Human anatomy and physiology. The ability to non-invasively extract visual information allowed, not only the three-dimensional representation of the internal organs and musculo-skeletal system, but also the simulation of surgical procedures, the execution of computer aided surgeries, the development of more accurate biomechanical models, the development of custom-made implants, among others. The combination of the most advanced medical imaging systems with the most advanced CAD and CAM techniques, may allow the development of custom-made implants that meet patient-speci c traits. The geometrical and functional optimization of these devices may increase implant life-expectancy, especially in patients with marked deviations from the anatomical standards. In the implant customization protocol from medical image data, there are several steps that need to be followed in a sequential way, namely: Medical Image Processing and Recovering; Accurate Image Segmentation and 3D Surface Model Generation; Geometrical Customization based on CAD and CAE techniques; FEA Optimization of the Implant Geometry; and Manufacturing using CAD-CAM Technologies. This work aims to develop the necessary procedures for custom implant development from medical image data. This includes the extraction of highly accurate three-dimensional representation of the musculo-skeletal system from the Computed Tomography imaging, and the development of customized implants, given the speci c requirements of the target anatomy, and the applicable best practices found in the literature. A two-step segmentation protocol is proposed. In the rst step the region of interest is pre-segmented in order to obtain a good approximation to the desired geometry. Next, a fully automatic segmentation re nement is applied to obtain a more accurate representation of the target domain. The re nement step is composed by several sub-steps, more precisely, the recovery of the original image, considering the limiting resolution of the imaging system; image cropping; image interpolation; and segmentation re nement over the up-sampled domain. Highly accurate segmentations of the target domain were obtained with the proposed pipeline. The limiting factor to the accurate description of the domain accuracy is the image acquisition process, rather the following image processing, segmentation and surface meshing steps. The new segmentation pipeline was used in the development of three tailor-made implants, namely, a tibial nailing system, a mandibular implant, and a Total Hip Replacement system. Implants optimization is carried with Finite Element Analysis, considering the critical loading conditions that may be applied to each implant in working conditions. The new tibial nailing system is able of sustaining critical loads without implant failure; the new mandibular endoprosthesis that allows the recovery of the natural stress and strain elds observed in intact mandibles; and the Total Hip Replacement system that showed comparable strain shielding levels as commercially available stems. In summary, in the present thesis the necessary procedures for custom implant design are investigated, and new algorithms proposed. The guidelines for the characterization of the image acquisition, image processing, image segmentation and 3D reconstruction are presented and discussed. This new image processing pipeline is applied and validated in the development of the three abovementioned customized implants, for di erent medical applications and that satisfy speci c anatomical needs.Um dos principais marcos da história moderna da medicina e a introdução da imagem médica, em meados da década de 1970. As tecnologias de imagem permitiram aumentar e potenciar o nosso conhecimento acerca da anatomia e fisiologia do corpo Humano. A capacidade de obter informação imagiológica de forma não invasiva permitiu, não são a representação tridimensional de órgãos e do sistema músculo-esquelético, mas também a simulação de procedimentos cirúrgicos, a realização de cirurgias assistidas por computador, a criação de modelos biomecânicos mais realistas, a criação de implantes personalizados, entre outros. A conjugação dos sistemas mais avançados de imagem medica com as técnicas mais avançadas de modelação e maquinagem, pode permitir o desenvolvimento de implantes personalizados mais otimizados, que vão de encontro as especificidades de cada paciente. Por sua vez, a otimização geométrica e biomecânica destes dispositivos pode permitir, quer o aumento da sua longevidade, quer o tratamento de pessoas com estruturas anatómicas que se afastam dos padrões normais. O processo de modelação de implantes a partir da imagem medica passa por um conjunto de procedimentos a adotar, sequencialmente, ate ao produto final, a saber: Processamento e Recuperação de Imagem; Segmentação de Imagem e Reconstrução tridimensional da Região de Interesse; Modelação Geométrica do Implante; Simulação Numérica para a Otimização da Geometria; a Maquinagem do Implante. Este trabalho visa o desenvolvimento dos procedimentos necessários para a criação de implantes personalizados a partir da imagem medica, englobando a extração de modelos ósseos geométricos rigorosos a partir de imagens de Tomografia Computorizada e, a partir desses modelos, desenvolver implantes personalizados baseados nas melhores praticas existentes na literatura e que satisfaçam as especificidades da anatomia do paciente. Assim, apresenta-se e discute-se um novo procedimento de segmentação em dois passos. No primeiro e feita uma pre-segmentação que visa obter uma aproximação iniciala região de interesse. De seguida, um procedimento de refinamento da segmentação totalmente automático e aplicada a segmentação inicial para obter uma descrição mais precisa do domínio de interesse. O processo de refinamento da segmentação e constituído por vários procedimentos, designadamente: recuperação da imagem original, tendo em consideração a resolução limitante do sistema de imagem; o recorte da imagem na vizinhança da região pre-segmentada; a interpolação da região de interesse; e o refinamento da segmentação aplicando a técnica de segmentação Level-Sets sobre o domínio interpolado. O procedimento de segmentação permitiu extrair modelos extremamente precisos a partir da informação imagiológica. Os resultados revelam que o fator limitante a descrição do domínio e o processo de aquisição de imagem, em detrimento dos diversos passos de processamento subsequentes. O novo protocolo de segmentação foi utilizado no desenvolvimento de três implantes personalizados, a saber: um sistema de fixação interna para a tíbia; um implante mandibular; e um sistema para a Reconstrução Total da articulação da Anca. A otimização do comportamento mecânico dos implantes foi feita utilizado o Método dos Elementos Finitos, tendo em conta os carregamentos críticos a que estes podem estar sujeitos durante a sua vida útil. O sistema de fixação interna para a tíbia e capaz de suportar os carregamentos críticos, sem que a sua integridade mecânica seja comprometida; o implante mandibular permite recuperar os campos de tensão e deformação observados em mandíbulas intactas; e a Prótese Total da Anca apresenta níveis de strain shielding ao longo do fémur proximal comparáveis com os níveis observados em dispositivos comercialmente disponíveis. Em suma, nesta tese de Doutoramento são investigados e propostos novos procedimentos para o projeto de implantes feitos por medida. São apresentadas e discutidas as linhas orientadoras para a caracterização precisa do sistema de aquisição de imagem, para o processamento de imagem, para a segmentação, e para a reconstrução 3D das estruturas anatómicas a partir da imagem medica. Este conjunto de linhas orientadoras é aplicado e validado no desenvolvimento de três implantes personalizados, citados anteriormente, para aplicações médicas distintas e que satisfazem as necessidades anatómicas específicas de cada paciente.Fundação para a Ciência e Tecnologia (FCT