Mandibular Morphology Research Articles

How did modern morphology evolve in the human mandible? The relationship between static adult allometry and mandibular variability in Homo sapiens

Key to understanding human origins are early Homo sapiens fossils from Jebel Irhoud, as well as from the early Late Pleistocene sites Tabun, Border Cave, Klasies River Mouth, Skhul, and Qafzeh. While their upper facial shape falls within the recent human range of variation, their mandibles display a mosaic morphology. Here we quantify how mandibular shape covaries with mandible size and how static allometry differs between Neanderthals, early H. sapiens, and modern humans from the Upper Paleolithic/Later Stone Age and Holocene (= later H. sapiens). We use 3D (semi)landmark geometric morphometric methods to visualize allometric trends and to explore how gracilization affects the expression of diagnostic shape features. Early H. sapiens were highly variable in mandible size, exhibiting a unique allometric trajectory that explains aspects of their ‘archaic’ appearance. At the same time, early H. sapiens share a suite of diagnostic features with later H. sapiens that are not related to mandibular sizes, such as an incipient chin and an anteroposteriorly decreasing corpus height. The mandibular morphology, often referred to as ‘modern’, can partly be explained by gracilization owing to size reduction. Despite distinct static allometric shape changes in each group studied, bicondylar and bigonial breadth represent important structural constraints for the expression of shape features in most Middle to Late Pleistocene hominin mandibles.

Three-Dimensional Evaluation of the Tongue Volume in Different Dentoskeletal Patterns - A Cone Beam Computed Tomographic Study.

Aim:The aim of this study is to evaluate tongue volume using cone-beam computed tomographic (CBCT) and its correlation to different growth patterns in patients.Materials and Methods:Sixty preorthodontic records of CBCT scans of subjects ranging from 14 to 25 age group from retrospective data of department were selected for the study. Patients were classified into three groups based on angle FMA; Group I (n = 20) with average growth pattern (FMA 22°–28°); Group II (n = 20) vertical growth pattern (FMA >28°); Group III (n = 25) horizontal growth pattern (FMA <20°). Tongue volume evaluation was done using Myrian® Software. Dentoskeletal features and parameters related to archform such as palatal vault depth, interpremolar, and intermolar distance were evaluated in all the subjects. ANOVA test was used for intergroup comparison of tongue volume and dentoskeletal parameters in all three groups. Correlation of the tongue volume to dentoskeletal parameters was done using Pearson's correlation test.Results:Mean tongue volume in Group I was 66.10 cm3, Group II, 66.04 cm3 and Group III was 66.72 cm3. There was a statistically significant correlation (P < 0.5) of tongue volume with palatal vault width, maxillary length, and mandibular interpremolar and intermolar distance among dentoskeletal parameters.Conclusion:Tongue volume was found equal in all groups despite the variation in growth patterns. Skeletal differences leading to different growth patterns were found to be related to mandibular morphology. The results indicate the indirect role of the tongue in causing malocclusion in orthodontic patients.

Analysis of Facial Skeletal Morphology: Nasal Bone, Maxilla, and Mandible.

The growth and development of facial bones are closely related to each other. The present study investigated the differences in the nasomaxillary and mandibular morphology among different skeletal patterns. Cephalograms of 240 participants were divided into 3 groups based on the skeletal pattern (Class I, Class II, and Class III). The dimensions of nasomaxilla (nasal bone length, nasal ridge length, nasal depth, palatal length, and maxillary height) and mandible (condylar length, ramus length, body length, symphysis length, and entire mandibular length) were measured. One-way analysis of variance and Pearson's correlation test were used for statistical analysis. No significant differences were observed among the skeletal patterns in terms of nasal bone length, palatal length, maxillary height, or condylar length. Class II had a significantly shorter ramus, mandibular body, and entire mandibular length compared with those of Class I and Class III. Nasal ridge length exhibited a significant moderate correlated with nasal bone length (correlation coefficient: 0.433) and maxillary height (correlation coefficient: 0.535). The entire mandibular length exhibited a significant moderate correlated with ramus length (correlation coefficient: 0.485) and body length (correlation coefficient: 0.536). In conclusion, nasal and maxillary dimensions exhibited no significant difference among the 3 skeletal patterns. Mandibular body and entire mandibular lengths were significantly positively correlations with Class III skeletal patterns.

Comparison of mandibular cross-sectional morphology between Class I and Class II subjects with different vertical patterns: based on CBCT images and statistical shape analysis

BackgroundThis study is aimed to (1) investigate the influence of sagittal and vertical patterns on mandibular cross-sectional morphology and to (2) provide visualized mandibular cross-sectional morphology in different groups with General Procrustes Analysis (GPA), canonical variance analysis (CVA) and discriminant function analysis (DFA).Methods324 cone-beam computed tomography (CBCT) images were collected to analyze mandibular cross-sectional morphology and were categorized into 12 groups according to sagittal and vertical pattern and gender. One-way analysis of variance (ANOVA) was used to compare the difference among the groups. Thirty equidistant points were marked along the contour of mandibular cross-section and GPA, CVA and DFA were applied.Results(1) Mandibular height in hyperdivergent groups was significantly higher than that in normodivergent and hypodivergent groups (P < 0.05). (2) Hypodivergent groups showed significantly wider upper third of mandibular width from symphysis to molar region than that in hyperdivergent group (P < 0.05), except for the premolar and molar regions in male groups (P > 0.05). (3) Class II hyperdivergent group showed narrowest lower third width in the molar region, with the mean value of 12.03 mm in females and 11.98 mm in males. (4) For males and females, the ratio between height and lower third width at symphysis was significantly higher in Class II hyperdivergent group than that in Class I hyperdivergent group (P < 0.05).Conclusions(1) The influence of vertical facial patterns on mandibular cross-sectional morphology is more obvious than that of sagittal skeletal pattern. (2) Subjects with increased vertical dimension presented with a remarkable “slimer” mandibular cross-sectional morphology at symphysis. (3) A deeper curve along the anterior contour of symphysis in Class II hyperdivergent group was noted with GPA.

Morphometric Analysis of the Mandible of Primitive Sabertoothed Felids from the late Miocene of Spain

How sabertoothed felids have evolved their iconic morphology remains unclear because of the patchy fossil record of early machairodontines. Batallones localities in the Madrid region (Spain) have the potential to clarify this as two sites have yielded hundreds of fossils of the early machairodontines Promegantereon ogygia and Machairodus aphanistus. Previous analyses suggested that these two sites are not contemporaneous and a morphological drift between cavities was described for these two species; characterizing intraspecific variability is thus important to better understand the evolution of machairodontines. To tackle this issue, we modelled 62 felid mandibles in 3D using a laser scanner. We applied 3D geometric morphometrics (3D GM) and linear morphometrics on these models to test for differences in populations and to better characterize the morphology of early machairodontines. Both linear measurements and 3D data reveal an absence of morphological changes in mandible shape between the two sites. Batallones machairodontines are closer to felines than to other, more derived machairodontines in mandibular morphology, suggesting the existence of rapid shift in the mandibular shape between primitive and derived members of the clade. Our analysis did not reveal any allometric relationship between the overall shape of the mandible when studied with 3D GM and body size. Finally, we reveal a previously overlooked diversity in felid mandibular condyles, with machairodontines having much larger and medially inclined condyles.

Geometric morphometrics of mandibles for dietary differentiation of Bovidae (Mammalia: Artiodactyla).

The mammalian family Bovidae has been widely studied in ecomorphological research, with important applications to paleoecological and paleohabitat reconstructions. Most studies of bovid craniomandibular features in relation to diet have used linear measurements. In this study, we conduct landmark-based geometric-morphometric analyses to evaluate whether different dietary groups can be distinguished by mandibular morphology. Our analysis includes data for 100 species of extant bovids, covering all bovid tribes and 2 dietary classifications. For the first classification with 3 feeding categories, we found that browsers (including frugivores), mixed feeders, and grazers are moderately well separated using mandibular shape. A finer dietary classification (frugivore, browser, browser–grazer intermediate, generalist, variable grazer, and obligate grazer) proved to be more useful for differentiating dietary extremes (frugivores and obligate grazers) but performed equally or less well for other groups. Notably, frugivorous bovids, which belong in tribe Cephalophini, have a distinct mandibular shape that is readily distinguished from all other dietary groups, yielding a 100% correct classification rate from jackknife cross-validation. The main differences in mandibular shape found among dietary groups are related to the functional needs of species during forage prehension and mastication. Compared with browsers, both frugivores and grazers have mandibles that are adapted for higher biomechanical demand of chewing. Additionally, frugivore mandibles are adapted for selective cropping. Our results call for more work on the feeding ecology and functional morphology of frugivores and offer an approach for reconstructing the diet of extinct bovids.

Gonial Angle by Lateral Cephalogram in Orthodontic Patients of a Tertiary Care Hospital: A Descriptive Cross-sectional Study.

The Gonial angle is an important parameter of the craniofacial complex for growth Patterns prediction. The gonial angle on lateral cephalometric radiograph represents the mandibular morphology concerning mandibular body and ramus. The objective of this study was to find out the mean value of gonial angle in lateral cephalometric radiographs of patients of orthodontic department in a tertiary care center. The descriptive cross-sectional study was conducted among patients from the Department of Orthodontics at People's Dental College and Hospital between 8th December 2020 to 8th February 2021 at People's Dental College and Hospital, Kathmandu, Nepal after obtaining Ethical approval (Reference Number. 01, CH100 09,2077/2078) by the Institutional Review Committee. A convenience sampling technique was used to collect 166 pre-treatment lateral cephalograms radiographs of patients between 17-30 years. Data were collected and entered using Statistical Package of Social Science 16. The mean value of gonial angle on lateral cephalogram radiographs was 132.84±3.70 in hyperdivergent, 119.94±5.57 in hypodivergent and 124.06±3.88 in normodivergent vertical skeletal patterns and between male and female were 132.52±4.32, 133.07±3.28 in hyperdivergent, 121.46±3.78, 119.14±6.42 in hypodivergent and 123.74±5.14, 123.94±3.90 in normodivergent vertical skeletal patterns of Orthodontic Patients. The gonial angle value on lateral cephalometric radiographs was greater in hyperdivergent than hypodivergent and normodivergent vertical skeletal patterns. The hyperdivergent vertical skeletal pattern of female was greater than of male patient's lateral cephalometric radiographs while hypodivergent and normodivergent vertical skeletal patterns of males were greater than female lateral cephalogram radiographs of Nepalese orthodontic patients.

Three‐dimensional analysis of the temporal bone and mandibular morphology in mandibular prognathism with facial asymmetry

AbstractThe aims of this study were to perform a three‐dimensional analysis of the craniofacial area, in particular, the temporal bone and to examine the morphological relationship between the temporal bone and asymmetry of the mandible in subjects with mandibular prognathism and facial asymmetry. Subjects were 50 adult orthognathic patients with facial asymmetry and mandibular prognathism. The initial computed tomographic data were reconstructed into three‐dimensional and multiplanar reconstruction images. Linear and angular measurements of the temporal bone and the mandible were obtained. Then deviated and non‐deviated sides were compared and the relationship between the temporal bone and mandibular morphology was investigated. The lengths of the mandibular body and ramus, the anteroposterior and vertical positions of the mandibular fossa, and the slant angle of the posterior surface of the petrous pyramid were significantly smaller (P &lt; .05) on the deviated side than on the non‐deviated side. Further, the left‐right differences in the temporal bone were positively correlated with a deviation of the mandible and differences in the lengths of the mandibular body and ramus (P &lt; .05). The results suggest that asymmetry of the temporal bone is closely related to mandibular asymmetry and might have an important role in the mechanism of facial asymmetry.

Evaluation of mandibular morphologic measurements and trabecular structure among subgroups of impacted mandibular third molars.

To investigate mandibular morphologic measurements and trabecular structures that may cause mandibular third molar (MM3) impaction according to MM3 subgroups. A total of 150 MM3 of 2175 panoramic radiographs (PRs) were reviewed. MM3s according to Winter (vertical), Pell & Gregory Class 1 and group: A, B, C on PRs were included in the study group. Fractal dimensions (FD) and mandibular morphologic measurements were evaluated. Statistical analysis for parametric values was performed using one-way analysis of variance (ANOVA). Statistical analysis for non-parametric values was performed using the Kruskal-Wallis H test. Statistically, a significant difference was found only in terms of angle of impaction among the groups of MM3 (p < 0.05) [Winter (vertical), and Pell & Gregory Class 1 and group A, B, C]. There was no difference among groups A, B, C in mandibular morphology and trabecular structure, but group C showed different characteristics than the other groups only in terms of impaction angle. The trabecular structure and morphometric properties except for the angle of impaction do not affect impacted MM3s with adequate retromolar space and vertical angle.

Facial skeleton morphology: does it reflect social stratification in an Early Mediaeval population from Great Moravia (ninth–tenth century AD, Czech Republic)?

This study examines the relationship between facial morphology and socioeconomic status within an Early Mediaeval population from the Mikulcice settlement. The agglomeration was the centre of the Great Moravian Empire in Central Europe and had a hierarchically structured society. The settlement can be divided on the basis of two criteria that possibly reflect socioeconomic classes: grave location (castle and sub-castle area) and grave goods (individuals with or without luxury grave goods). As study material, we utilized CT images of adult skulls. We divided the facial skeleton into two morphological regions: the upper face (49 males and 45 females) and the mandible (47 males and 41 females), which were investigated by landmark-based methods of geometric morphometrics. The results suggest that the population was highly stratified and that both of the criteria could reflect different genetic backgrounds, lifestyles or environmental conditions. Significant differences in upper face morphology were found between individuals with or without luxury grave goods, and significant differences in mandibular morphology between individuals buried in the castle and sub-castle areas. Although the morphology of the facial skeleton has a multi-etiological nature and all its parts are influenced by a complex of internal and external factors, upper face morphology based on grave goods may be more influenced by genetic variability between the study groups in the context of patrilocality and patrilineality, which were conventional practices in Early Mediaeval societies. On the other hand, mandibular morphology may be more influenced by external conditions (probably by a different diet).

Oral health status of children and young adults with maple syrup urine disease in Turkey

BackgroundMaple syrup urine disease (MSUD) is an inherited disorder clinically characterized by ketoacidosis, seizures, coma, psychomotor delay, and intellectual disability. The treatment requires a life-long protein-restricted diet, rich in carbohydrates and fats, supplemented with a medical amino acid formula. Diet, oral health and general health influence each other in a vicious cycle. The aim of this study was to investigate the oral health status of children and young adults with MSUD in Turkey.MethodsA descriptive study was conducted on patients with MSUD who applied for routine follow-up to the pediatric metabolic diseases clinic at Hacettepe University, Children's Hospital in Ankara, Turkey in a 12-month period. Patients with any other concomitant genetic diseases and acute infection were excluded. A total of twenty-five patients were enrolled and underwent oral examination including DMFT/S, dmft/s (decayed/missing/filled teeth/surfaces for deciduous and primary teeth, respectively), plaque and gingival indices. Panoramic radiographs were obtained in 12 cooperative patients.ResultsMean age was 9.88 ± 5.68 s.d years. More than half of the parents had only primary school level education, and low income. Fourteen patients consumed medical formula during or right before sleep. Fourteen patients reported caries-associated pain. Gingival inflammation was present in all 15 patients who cooperated for evaluation. Seven out of twelve patients had at least one dental anomaly or alterations in mandibular morphology. Five patients had previously been treated for caries under general anesthesia. To our knowledge, this is the first study to document oral clinical and radiologic findings in patients with MSUD.ConclusionsImpaired oral health was observed in this rare disease population. Regular dental referral by physicians, preventive measures and dental treatments should be included in multidisciplinary management of maple syrup urine disease to promote oral health.

Correlation of Pharyngeal Airway Dimensions with Maxillomandibular Skeletal Relation and Mandibular Morphology in Subjects with Skeletal Class I and Class II Malocclusions and Different Growth Patterns: A Cephalometric Study in Selected Local Population.

Objectives:To test the hypothesis that there is no positive correlation between skeletal Class II and mandibular morphology with pharyngeal dimensions in subjects with different growth patterns.Materials and Methods:Lateral cephalograms of 60 patients were collected and divided into 2 groups, comprising of 30 in each group. Group 1 consisted of cephalograms of patients having Class I malocclusion, and was further divided into subgroups. 1a) Class I with normal growth 1b) Class I with vertical growth. Group 2 consisted of cephalograms of patients having class II malocclusion and was further divided into subgroups 2a) Class II with normal growth, 2b) Class II with vertical growth.Results:The results showed that the estimated marginal mean for upper pharyngeal width in class I malocclusion group was 8.56 mm, for class II malocclusion group was 7.80 mm, for normal growth individuals was 9.73 mm and that for vertical growth individuals was 6.63 mm. The estimated marginal mean for lower pharyngeal width in class I malocclusion group was 9.62 mm, in class II malocclusion group was 9.10 mm, in normal growth individuals was 8.95 mm and that in vertical growth individuals was 9.77 mm. The estimated marginal mean for pharyngeal area in class I malocclusion group is 330.13 sq.mm, in class II malocclusion group is 308.17 sq.mm, in normal growth individuals is 328.47sq.mm and that in vertical growth individuals is 309.83 sq.mm.Conclusions:The null hypothesis for this study, as per the statistical analysis, has been rejected.

Application and performance of artificial intelligence technology in forensic odontology - A systematic review.

Forensic odontology (FO) mainly deals with the identification of the individual through the remains, which mainly includes teeth and jawbones. Artificial intelligence (AI) technology has proven to be a breakthrough in providing reliable information in decision making in forensic sciences. This systematic review aimed to report on the application and performance of AI technology in FO. The data was gathered through searching for the articles in the renowned search engines, which have been published between January 2000 - June 2020. QUADAS-2 was adopted for the risk of bias analysis of the included studies. AI technology has been widely applied in FO for identifying bite-marks, predicting mandibular morphology, gender determination, and age estimation. Most of these AI models are based on either artificial neural networks (ANNs) or convolutional neural networks (CNNs). The results of the studies are promising. Studies have reported that these models display accuracy and precision equivalent to that of the trained examiners. These models can be promising tools when identifying victims of mass disasters and as an additive aid in medico-legal situations.

Ingestive behaviors in bearded capuchins (Sapajus libidinosus)

The biomechanical and adaptive significance of variation in craniodental and mandibular morphology in fossil hominins is not always clear, at least in part because of a poor understanding of how different feeding behaviors impact feeding system design (form–function relationships). While laboratory studies suggest that ingestive behaviors produce variable loading, stress, and strain regimes in the cranium and mandible, understanding the relative importance of these behaviors for feeding system design requires data on their use in wild populations. Here we assess the frequencies and durations of manual, ingestive, and masticatory behaviors from more than 1400 observations of feeding behaviors video-recorded in a wild population of bearded capuchins (Sapajus libidinosus) at Fazenda Boa Vista in Piauí, Brazil. Our results suggest that ingestive behaviors in wild Sapajus libidinosus were used for a range of food material properties and typically performed using the anterior dentition. Coupled with previous laboratory work indicating that ingestive behaviors are associated with higher mandibular strain magnitudes than mastication, these results suggest that ingestive behaviors may play an important role in craniodental and mandibular design in capuchins and may be reflected in robust adaptations in fossil hominins.

Geometric morphometrics of mandibular shape in the dwarf fat-tailed jerboa: relevancy for trinomial taxonomy

Abstract We explore the pattern of spatial variation in mandibular morphology in relation to subspecific taxonomy in the dwarf fat-tailed jerboa, Pygeretmus pumilio. The unguided k-means clustering on mandible shape scores, partitioned populations into two clusters, corresponding to western and eastern populations. These clusters nearly perfectly matched the two subspecies groups (pumilio and potanini groups) recognized in an independent study based on the morphology of the glans penis. The mandible, although under environmental pressure, has retained a sufficient amount of taxonomic information to retrieve grouping closely resembling the one derived from a sexually selective trait. We recommend morphometrics of the mandible as a routine step in addressing variations in mammals at species and subspecies levels. We also stress the advantage of unsupervised k-clustering in testing null expectation in subspecies taxonomies. However, the power of this approach has its limitations and in our analysis, the k-clustering failed to retrieve subspecies in the potanini group.

A Geometric Morphometric Analysis of Geographic Mandibular Variation in the Dwarf Gerbil Gerbillus nanus (Gerbillinae, Rodentia)

Previous studies have demonstrated the pliability and adaptability of mammalian mandibles in response to different ecological demands such as food availability. The dwarf gerbil Gerbillus nanus has a wide distribution in Asia in which it encounters varied environments. These varied environments can house different food resources and it would be adaptively advantageous for the opportunistic rodents to have mandibles best suited for the most prevalent food resource. Geometric morphometric analysis was used to test this hypothesis by examining mandibular variation in 436 G. nanus specimens sampled from 44 localities. Based on this sample, mandibular morphology seems to be highly conserved in this species, with both size and shape being non-significantly different between pairs of geographic groups (i.e., locality clusters) and ecoregions. Mandibular size and shape are both not strongly predicted by 48 examined environmental variables. Despite this, the most variable aspect of mandibular shape was associated with its caudal regions, spanning from the coronoid process to the ventral mandibular border. These are regions of temporalis and masseter muscle attachments and thus mandibular variation could be associated with differential (potentially plastic) masticatory adaptations.

The Hypoplasic Mandible: What Makes it Different From the Healthy Child?

This study aimed to analyze the morphology of the hypoplasic mandible and its evolution during the growth period to better understand how it differs from the pediatric healthy mandible. Three-dimensional mandibular models of hypoplasic and healthy children aged from 39 gestational weeks to 7 years old were analyzed with a morphometric method including data clustering. Morphological distinctions between pathological and healthy mandibles were highlighted. Bilateral and unilateral mandibular hypoplasia were distinguished. The study sample was composed of 31 hypoplasic children and as many sex- and age-matched healthy children. Morphological distinctions between pathological and healthy mandibles were highlighted only from the first year of life. In bilateral hypoplasia, the overall mandibular dimensions were reduced while there was only a ramus asymmetry in unilateral mandibular hypoplasia (mean ± SD of the difference between the Grp03c and Grp03b subgroups: 6.80 ± 6.37 - P value = 1.64e-3 for the height of the left ramus versus 0.18 ± 4.18 - P value = .82 for the height of the right ramus). Supervised classification trees were built to identify the pathology and discriminate unilateral from bilateral mandibular hypoplasia (prediction rates = 81% and 84%, respectively). Based on a morphometric analysis, we demonstrated that mandibular hypoplasia significantly impacts the mandibular morphology only from the first year of life, with a distinction between bilateral and unilateral hypoplasia.

Morphological divergence in giant fossil dormice.

Insular gigantism-evolutionary increases in body size from small-bodied mainland ancestors-is a conceptually significant, but poorly studied, evolutionary phenomenon. Gigantism is widespread on Mediterranean islands, particularly among fossil and extant dormice. These include an extant giant population of Eliomys quercinus on Formentera, the giant Balearic genus †Hypnomys and the exceptionally large †Leithia melitensis of Pleistocene Sicily. We quantified patterns of cranial and mandibular shape and their relationships to head size (allometry) among mainland and insular dormouse populations, asking to what extent the morphology of island giants is explained by allometry. We find that gigantism in dormice is not simply an extrapolation of the allometric trajectory of their mainland relatives. Instead, a large portion of their distinctive cranial and mandibular morphology resulted from the population- or species-specific evolutionary shape changes. Our findings suggest that body size increases in insular giant dormice were accompanied by the evolutionary divergence of feeding adaptations. This complements other evidence of ecological divergence in these taxa, which span predominantly faunivorous to herbivorous diets. Our findings suggest that insular gigantism involves context-dependent phenotypic modifications, underscoring the highly distinctive nature of island faunas.

Correlation between mandibular morphology and masticatory muscle thickness in normal occlusion and mandibular prognathism.

ObjectivesThe aim of this study was to evaluate the relationship between masticatory muscle thickness and mandibular morphology in young Korean adults with normal occlusion and mandibular prognathism.Patients and MethodsMultidetector computed tomography (MDCT) was used to measure the masticatory muscle thickness on the right side in 100 Korean young adults (50 normal occlusion group, 50 mandibular prognathism group). Cephalometric analysis was done to measure mandibular morphology. Pearson correlation analysis was done to investigate the relationship between the masticatory muscle thickness and mandibular morphometry.ResultsThe four masticatory muscles showed positive correlation with intergonial width in all subjects. All muscles, except temporalis, positively correlated with height of the ramus and mandibular length. Positive correlation was also observed in all muscles, except medial pterygoid, with thickness of the ramus. In the normal occlusion group, all four masticatory muscles showed positive correlation with intergonial width and ramus thickness. Positive correlation was also observed in all muscles (except lateral pterygoid) with mandibular length. Masseter and lateral pterygoid positively correlated with height of the ramus. In the mandibular prognathism group, all masticatory muscles, except lateral pterygoid, showed positive correlation with intergonial width. The masseter muscle showed negative correlation with ANB.ConclusionThe results suggest a positive correlation of the thickness of masticatory muscles with both horizontal and vertical dimensions of the mandible. However, thickness of the masseter was found to decrease in patients with increasing severity of mandibular prognathism.

Use of artificial intelligence to recover mandibular morphology after disease

Mandibular tumors and radical oral cancer surgery often cause bone dysmorphia and defects. Most patients present with noticeable mandibular deformations, and doctors often have difficulty determining their exact mandibular morphology. In this study, a deep convolutional generative adversarial network (DCGAN) called CTGAN is proposed to complete 3D mandibular cone beam computed tomography data from CT data. After extensive training, CTGAN was tested on 6 mandibular tumor cases, resulting in 3D virtual mandibular completion. We found that CTGAN can generate mandibles with different levels and rich morphology, including positional and angular changes and local patterns. The completion results are shown as tomographic images combining generated and natural areas. The 3D generated mandibles have the anatomical morphology of the real mandibles and transition smoothly to the portions without disease, showing that CTGAN constructs mandibles with the expected patient characteristics and is suitable for mandibular morphological completion. The presented modeling principles can be applied to other areas for 3D morphological completion from medical images.Clinical trial registration: This study is not a clinical trial. Patient data were only used for testing in a virtual environment. The use of the digital data used in this study was ethically approved.