The functional matrix hypothesis revisited. 3. The genomic thesis

Effects of Diet Consistency on Rat Maxillary and Mandibular Growth within Three Generations-A Longitudinal CBCT Study

BACKGROUND

In this study, wistar rats were used to examine the impact of diet consistency on maxillary and mandibular growth over three generations.

METHODS

In this investigation, a breeding sample of 60 female and 8 male wistar rats was used. Measuring was only performed on female animals. The first generation's primary breeding sample consisted of 20 female wistar rats that were 30 days old and 4 male rats that were also 30 days old; two subsequent generations were created from these animals. At the age of 100 days, CBCTs were collected of all male rats. Twenty-eight craniofacial landmarks were selected for the linear measurements on stl format extracted from the DICOM files. A Bonferroni test was performed for the statistical analysis.

RESULTS

Means of measurements of all soft diet groups compared to corresponding measurements of the hard diet groups were significantly different. According to linear measurements, there was statistical difference on the maxillary measurements between the soft diet groups of the first and third generation, while the rest did not appear to have any statistical difference. There was significant difference for the mandibular dimensions only when the first generation soft diet group was compared with the third generation soft diet group.

CONCLUSIONS

Food consistency has a significant impact on the growth and development of the maxilla and mandible. Soft diet habits may result in retrognathic mandible, and narrower maxilla.

Heritability of cephalometric variables of airway morphology in twins with completed active growth

BACKGROUND

The interplay between genetic and environmental impacts on dental and facial morphology has been widely analyzed, but little is known about their relative contributions to airway morphology. The aim of this study was to evaluate the genetic and environmental influences on the cephalometric variables of airway morphology in a group of postpubertal twins with completed craniofacial growth.

MATERIALS AND METHODS

The materials comprised lateral head cephalograms of 94 pairs of twins (50 monozygotic, 44 dizygotic) with completed craniofacial growth. Zygosity was determined using 15 specific DNA markers. The computerized cephalometric analysis included 22 craniofacial, hyoideal, pharyngeal structural linear and angular variables. Genetic analysis and heritability estimation were performed using maximum likelihood genetic structural equation modeling (GSEM). Principal component analysis (PCA) was used to assess the correlations between cephalometric measurement variables.

RESULTS

Upper airway dimensions showed moderate to high genetic determination (SPPW-SPP and U-MPW: a² = 0.64 and 0.5, respectively). Lower airway parameters showed only common and specific environmental determination (PPW-TPP a² = 0.24, e² = 0.38; LPW-V c² = 0.2, e² = 0.63; PCV-AH c² = 0.47, e² = 0.28). The relationship between the maxilla and the hyoid bone (for variables PNS-AH, ANS-AH d² = 0.9, 0.92, respectively) showed very strong additive genetic determination. The size of the soft palate was affected by additive and dominant genes. Its length (SPL) was strongly influenced by dominant genes, while its width (SPW) showed a moderate additive genetic influence. Owing to correlations in the behavior of variables, the data could be expressed in 5 principal components that jointly explained 36.8% of the total variance.

CONCLUSIONS

The dimensions of the upper airway are strongly determined by genes, while the parameters of the lower airway depend mainly on environmental factors.

TRIAL REGISTRATION

The protocol has been approved by the Kaunas Regional Ethical Committee (No. BE - 2-41., May 13, 2020).

Long-Term Effect of Diet Consistency on Mandibular Growth within Three Generations: A Longitudinal Cephalometric Study in Rats

BACKGROUND

This study investigated the effect of diet consistency on mandibular growth of Wistar rats through three generations.

METHODS

A total breeding sample of 60 female and 8 male Wistar rats were used in this study. Measurements took place only on female animals. Twenty female Wistar rats at 30 days old and four male rats at 30 days old comprised the primary breeding sample of the first generation, and from these animals two different generations were reproduced. Lateral cephalometric X-rays were taken from all female rats at the age of 100 days. A total of 7 craniofacial landmarks were selected for the linear measurements, and 12 curves and 90 landmarks were selected for geometric morphometric analysis of the lateral X-rays. Bonferroni test and a permutation test were performed for the statistical analysis.

RESULTS

Means of measurements of all soft diet groups compared to hard diet groups were significantly smaller. According to linear measurements, there was a significant difference only between the first-generation soft diet with the third-generation soft diet group. According to geometric morphometric analysis, the statistical differences appeared on the condylar process and the angle of the mandible.

CONCLUSIONS

The soft diet could be responsible for less mandibular growth, and this information might be passing through generations.

Comparison of Mandibular Volume and Linear Measurements in Patients with Mandibular Asymmetry

In patients with mandibular asymmetry, the volume of the mandible divided by the mandibular median plane is significantly larger on the non-deviated (N-Dev) side than on the deviated (Dev) side. However, it has been reported that there is no significant difference between the volumes of the N-Dev and Dev sides when the mandibular ramus and body are divided. The purpose of this study was to investigate which region is responsible for the volume difference between the N-Dev and Dev sides. Cone Beam Computed Tomography (CBCT) images of patients with mandibular asymmetry were analyzed by measuring the volume, and linear analysis of the mandibular body, ramus, and condyle on the N-Dev and Dev side was performed. In this study, CBCT images of 37 patients (8 Japanese, 16 Korean, and 13 Egyptian) aged ≥ 18 years with mandibular asymmetry (men: 20, women: 17) were used to evaluate mandibular asymmetry. In patients with mandibular asymmetry, the N-Dev side showed significantly larger values than the Dev side for both volume and linear condyle, ramus, and mandibular body measurements. These results do not differ according to sex or ethnicity. Therefore, it is suggested that the N-Dev side of mandibular asymmetry is large without any regional specificity in pathophysiology.

Sagittal suture strain in capuchin monkeys (Sapajus and Cebus) during feeding

OBJECTIVES

Morphological variation in cranial sutures is used to infer aspects of primate feeding behavior, including diet, but strain regimes across sutures are not well documented. Our aim is to test hypotheses about sagittal suture morphology, strain regime, feeding behavior, and muscle activity relationships in robust Sapajus and gracile Cebus capuchin primates.

MATERIALS AND METHODS

Morphometrics of sinuosity in three regions of the sagittal suture were compared among museum specimens of Sapajus and Cebus, as well as in robust and gracile lab specimens. In vivo strains and bilateral electromyographic (EMG) activity were recorded from these regions in the temporalis muscles of capuchin primates while they fed on mechanically-varying foods.

RESULTS

Sapajus and the anterior suture region exhibited greater sinuosity than Cebus and posterior regions. In vivo data reveal minor differences in strain regime between robust and gracile phenotypes but show higher strain magnitudes in the middle suture region and higher tensile strains anteriorly. After gage location, feeding behavior has the most consistent and strongest impact on strain regime in the sagittal suture. Strain in the anterior suture has a high tension to compression ratio compared to the posterior region, especially during forceful biting in the robust Sapajus-like individual.

DISCUSSION

Sagittal suture complexity in robust capuchins likely reflects feeding behaviors associated with mechanically challenging foods. Sutural strain regimes in other anthropoid primates may also be affected by activity in feeding muscles.

Endocranial anatomy of the Guercy 1 early Neanderthal from Baume Moula-Guercy (Soyons, Ardèche, France)

We provide the first comparative description of the endocranium of the Guercy 1 Early Neanderthal and examine its affinities to Preneanderthals, Neanderthals, and Homo sapiens. The Guercy 1 cranium derives from deposits chronostratigraphically and biostratigraphically dated to the Eemian Interglacial (MIS 5e). For comparative purposes, we compiled a sample of European and Southwest Asian subadult and adult Middle-to-Late Pleistocene hominins (≈MIS 12-MIS 1; N = 65). We sampled both a Preneanderthal-Neanderthal group and a Homo sapiens group. The Preneanderthal-Neanderthal group was further divided into three time-successive subgroups defined by associated MIS stages. Metric and morphological observations were made on original fossils and physical and virtual endocranial reconstructions. Guercy 1 and other Early Neanderthals, differ from Preneanderthals by increased development of the prefrontal cortex, precentral and postcentral gyri, inferior parietal lobule, and frontoparietal operculum. Early Neanderthal differ, in general, from Late Neanderthals by exhibiting less development in most of the latter brain structures. The late group additionally differentiates itself from the early group by a greater development of the rostral superior parietal lobule, angular gyrus, superior and middle temporal gyri, and caudal branches of the superior temporal gyrus. Endocranial morphology assessed along the Preneanderthal-Neanderthal sequence show that brain structures prominent in Preneanderthals are accentuated in Early-to-Late Neanderthals. However, both the Early and Late groups differentiate themselves by also showing regionally specific changes in brain development. This pattern of morphological change is consistent with a mosaic pattern of neural evolution in these Middle-to-Late Pleistocene hominins.

Functional Orthodontic Treatment of Mandibular Condyle Fractures in Children and Adolescent Patients: An MRI Follow-Up

BACKGROUND

The purpose of this study was to retrospectively evaluate and follow up a conservative treatment approach with functional orthodontic appliances for the management of mandibular condyle fractures in children and adolescent patients.

METHODS

Between 2020 and 2022, the treatment records of patients with mandibular condyle fractures receiving a functional orthodontic treatment (FOT) were evaluated. In addition to the clinical and functional findings, magnetic resonance images of the mandibular condyles and surrounding structures were assessed.

RESULTS

Out of 61 patients, 8 met the inclusion criteria. The follow-up examination records showed no functional limitations. In 75% of cases, mild midline deviations persisted (mean 1.1 mm) without significant alterations to the occlusal relationships. Magnetic resonance imaging (MRI) showed the remodeling of the condyles and the restitution of the ramus heights, even in dislocated and displaced fractures. In three cases, a partial displacement of the articular disc was observed at the follow-up. No differences in the remodeling patterns were noted depending on age, sex, or fracture location.

CONCLUSIONS

A FOT led to favorable functional and morphologic outcomes, supporting the concept of a conservative functional approach in children and adolescent patients. Functional adjunctive therapy should be considered in the conservative treatment of mandibular condyle fractures in growing patients.

Effect of Diet Consistency on Rat Mandibular Growth: A Geometric Morphometric and Linear Cephalometric Study

Simple Summary

Craniofacial growth is affected by different environmental factors. One of these factors that seems to affect mandibulofacial growth is mastication. Diet consistency leads to different masticatory forces during mastication. Various researchers looked over the effect of diet consistency on craniofacial growth and more specifically on the mandible. The question of how diet consistency affects mandibular growth is still controversial since various studies had different results on that aspect. The results of this study support that there is a major effect of diet consistency on mandibular morphology. Thus, it contributes to a better understanding of evolution of mandibular growth.

Abstract

Background: Our study intended to investigate the null hypothesis that there is no effect of diet consistency on rat mandibular growth. Methods: A total sample of 24 female wistar rats, 30 days old, was used in this study. In the first group, the rats were fed soft diet and in the second group, they were fed hard diet for 60 days. On the 60th day, the rats were sedated and lateral cephalometric X-rays were taken. Lateral cephalometric X-rays were digitized with 7 craniofacial landmarks for the linear measurements, as well as with 12 curves and 90 landmarks, of which 74 were semilandmarks and 16 were fixed landmarks for morphometric analysis. These landmarks were exposed to Procrustes superimposition and Principal Component Analysis (PCA) to describe the shape variability of the mandible. Results: Means measurements of the soft diet group compared to those of the hard diet group were significantly different in linear and morphometric analysis measurements. The soft diet group of wistar rats revealed significant changes on the condyle (smaller), the angle of the mandible, and on the body of the mandible. Conclusions: Diet consistency affects the craniofacial growth of rats. Soft diet could be responsible for less mandibular growth.

Anatomic development of the upper airway during the first five years of life: A three-dimensional imaging study

Purpose

Normative data on the growth and development of the upper airway across the sexes is needed for the diagnosis and treatment of congenital and acquired respiratory anomalies and to gain insight on developmental changes in speech acoustics and disorders with craniofacial anomalies.

Methods

The growth of the upper airway in children ages birth to 5 years, as compared to adults, was quantified using an imaging database with computed tomography studies from typically developing individuals. Methodological criteria for scan inclusion and airway measurements included: head position, histogram-based airway segmentation, anatomic landmark placement, and development of a semi-automatic centerline for data extraction. A comprehensive set of 2D and 3D supra- and sub-glottal measurements from the choanae to tracheal opening were obtained including: naso-oro-laryngo-pharynx subregion volume and length, each subregion’s superior and inferior cross-sectional-area, and antero-posterior and transverse/width distances.

Results

Growth of the upper airway during the first 5 years of life was more pronounced in the vertical and transverse/lateral dimensions than in the antero-posterior dimension. By age 5 years, females have larger pharyngeal measurement than males. Prepubertal sex-differences were identified in the subglottal region.

Conclusions

Our findings demonstrate the importance of studying the growth of the upper airway in 3D. As the lumen length increases, its shape changes, becoming increasingly elliptical during the first 5 years of life. This study also emphasizes the importance of methodological considerations for both image acquisition and data extraction, as well as the use of consistent anatomic structures in defining pharyngeal regions.

Cranial-Vertebral-Maxillary Morphological Integration in Down Syndrome

Background: Morphological integration refers to the tendency of anatomical structures to show correlated variations because they develop in response to shared developmental processes or function in concert with other structures. The objective of this study was to determine the relationships between the dimensions of different cranial-cervical-facial structures in patients with Down syndrome (DS). Methodology: The study group consisted of 41 individuals with DS who had undergone cone-beam computed tomography (CBCT) at the Dental Radiology Unit of the University of Santiago de Compostela (Spain). In the historical archive of this same unit, 41 CBCTs belonging to individuals with no known systemic disorders or severe malformations of the maxillofacial region were selected, forming an age and sex-matched control group. Twenty-nine measurements were performed on each participant’s CBCT images, which were grouped into three blocks: atlantoaxial dimensions, craniovertebral dimensions and cephalometric dimensions. To determine whether there were significant differences between the dimensions obtained in the DS and control groups, we applied multiple analysis of variance and linear discriminant analysis tests. The analysis of the association between blocks (in pairs) was performed with the canonical correlation analysis test. Results: The dimensions evaluated in the three blocks of variables of individuals with DS differ significantly from those of nonsyndromic controls (p < 0.001). The highest discriminative capacity to identify controls and patients with DS was obtained with the cephalometric dimensions (87.5%). With regard to the association between blocks (two-by-two measurements), we found no significant relationship in the DS group. However, we confirmed a statistically significant correlation between all pairs of blocks of variables in the controls, especially between the atlantoaxial and cephalometric dimensions (p < 0.001) and between the craniovertebral and cephalometric dimensions (p < 0.001). Conclusions: Our results confirm a very poor morphological integration of the cranial-cervical-maxillary complex in individuals with DS. This finding reinforces the proposal that gene overload enhances the channeling process.

Impact of Diet Consistency on the Mandibular Morphology: A Systematic Review of Studies on Rat Models

Apart from genetics, environmental factors, such as food consistency, may affect craniofacial morphology and development. The present systematic review aims to systematically investigate and appraise the available evidence regarding the effect of diet consistency on the anatomical structures of the basal bone of the rat mandible. The search was performed without restrictions in five databases (PubMed, Scopus, Web of Science, ProQuest Dissertations and Theses Global, including grey literature) and hand searching through January 2022. A total of 14,904 references were initially identified, and 16 articles were finally included in the systematic review. Rats that consumed hard diets were found to exhibit an increase inbigonial width, corpus height, condylar depth, condylar base inclination, condylar process inclination, mandibular plane inclination, height and length of angular process, mandibular body height, depth of antegonial notch, growth rate in the gonial angle, angular process convexity and height of condylar process. It was also noted that mandibular depth, mandibular height, ramus angle and angle between the angular process and mandibular plane were decreased in rats that were fed with a hard diet. On the other hand, there were conflicting results about the growth of mandibular length and width, corpus length, mandibular body length, ramus height, condylar length and width, gonial angle and height of coronoid process. From the abovementioned results, it can be concluded that food consistency may affect the morphology of anatomical structures and the overall growth and development of rat mandibles in various ways.

Combating Constraints of the Functional Matrix: The Importance of Overcorrection in Pediatric Craniofacial Surgery

Background:

To effectively manipulate the bone, particularly in the growing patient, the craniofacial surgeon must understand the principles related to bone-based reconstruction. A theory of craniofacial growth that is both biologically accurate and clinically relevant is thus needed.

Methods:

A historical review of major findings across various disciplines (including orthopedic surgery, anatomy, embryology, orthodontics, and cell biology) will be covered, as it pertains to the concept of the functional matrix of the craniofacial skeleton.

Results:

The functional matrix dictates the interplay between the soft tissue envelope and bone grafts, thus guiding donor site choice and inset methods. The soft tissue may also warrant the use of bony hypercorrection especially in cranial vault remodeling. Control of both bone and boundaries of the soft tissue functional matrix can be achieved via distraction osteogenesis.

Conclusion:

The soft tissue functional matrix must be accounted for during craniofacial bone grafting, mobilizing osteotomies, and distraction osteogenesis if optimal aesthetic results are to be obtained using the least amount of procedures.

Prevalence of maxillary sinus hypoplasia and association with variations in the sinonasal complex: a cone beam CT study

OBJECTIVE

Understanding of maxillary sinus hypoplasia (MSH) and associated sinonasal variants is paramount to the diagnostic and therapeutic success of maxillary sinus and maxillary dental implant surgery. The purpose of this work was to explore the prevalence of MSH, frequency of mucosal thickening, and anatomical variations in the sinonasal complex.

METHODS

Retrospective case-control design based on cone beam CT images of dental patients with MSH and matched for age and gender. MSH type and sinonasal variables were recorded.

RESULTS

One thousand three hundred seventy cone beam CT scans were analyzed for MSH. MSH prevalence was 6% (n=82), matched with 82 controls= 100 females and 64 males, mean age 37.1±14.1 years. Most MSH were type I, 69.5%, 80.5% unilateral, 65.9% associated with no or mild mucosal thickening. Associated sinonasal anatomical variations were <27% except for deviated/hyperplastic (DH) meatus, 48.8%. Within the MSH group, significant associations were presented between MSH type, mucosal thickening, and DH nasal meatus. MSH group vs controls showed a significant difference in mucosal thickening (OR 5.2, 95% CI 2.0-17.3) and DH meatus (OR 1.6, 95% CI 1.4-2.1).

CONCLUSIONS

A hypoplastic maxillary sinus with abnormal or absent uncinate process is associated with advanced mucosal thickening and may present with altered anatomy of the lateral wall of the nasal cavity causing its approximation to the orbital floor.

CLINICAL RELEVANCE

Pre-surgical knowledge of altered anatomy in the sinonasal complex is crucial in dental implant or sinus surgery.

The use of mini-implants for provisional prosthetic rehabilitation in growing patients: a critical review

PURPOSE

To critically review the literature using mini-implants for prosthetic rehabilitation of growing patients and to analyze the survival rates and clinical behavior of mini-implants.

STUDY SELECTION

Controlled clinical trials and case reports published in English, from January 2006 to October 2018, in a peer-reviewed journal in PubMed, Scopus, LILACS, and Cochrane Library databases. Studies using mini-implants for prosthetic rehabilitation in growing patients were included. Articles reporting mini-implants with a diameter greater than 3 mm, recruitment of adult participants, use of implants with other purposes than prosthodontic rehabilitation, and with a follow-up period shorter than 1 year, were excluded from the analysis. The selection was performed independently by two reviewers.

RESULTS

The selection resulted in the inclusion of eight articles. Although the studies presented heterogeneous protocols and follow-ups (varying from 1 to 8 years), only one case of failure was reported, which corresponded to crown displacement. All rehabilitation procedures were performed in the anterior region using mini-implants with different diameters (1.3-2.9 mm) and lengths (9-14 mm). The prosthetic rehabilitation included individual crowns and/or overdentures.

CONCLUSIONS

Mini-implant prosthetic rehabilitation seems to be a viable and promising option for provisional rehabilitation of growing patients, since it seems to preserve the bone structure while restoring function and esthetics until growth ceases, when then mini-implants can be replaced by standard implants.

Nose approximation among South African groups from cone-beam computed tomography (CBCT) using a new computer-assisted method based on automatic landmarking

Considering the high demand for the identification of unknown remains in South Africa, a need exists to establish reliable facial approximation techniques that will take into account sex and age and, most importantly, be useful within the South African context. This study aimed to provide accurate statistical models for predicting nasal soft-tissue shape from information about the underlying skull subtract among a South African sample. The database containing 200 cone-beam computer tomography (CBCT) scans (100 black South Africans and 100 white South Africans). The acquisition and extraction of the 3D relevant anatomical structures (hard- and soft-tissue) were performed by an automated three-dimensional (3D) method based on an automatic dense landmarking procedure using MeVisLab © v. 2.7.1 software. An evaluation of shape differences attributed to known factors (ancestry, sex, size, and age) was performed using geometric morphometric and statistical models of prediction were created using a Projection onto Latent Structures Regression (PLSR) algorithm. The accuracy of the estimated soft-tissue nose was evaluated in terms of metric deviations on training and un-trained datasets. Our findings demonstrated the influence of factors (sex, aging, and allometry) on the variability of the hard- and soft-tissue among two South African population groups. This research provides accurate statistical models optimized by including additional information such as ancestry, sex, and age. When using the landmark-to landmark distances, the prediction errors ranged between 1.769mm and 2.164mm for black South Africans at the tip of the nose and the alae, while they ranged from 2.068mm to 2.175mm for the white subsample. The prediction errors on un-trained data were slightly larger, ranging between 2.139mm and 2.833mm for the black South African sample at the tip of the nose and the alae and ranging from 2.575mm to 2.859mm for the white South African sample. This research demonstrates the utilization of an automated 3Dmethod based on an automatic landmarking method as a convenient prerequisite for providing a valid and reliable nose prediction model that meets population-specific standards for South Africans.

Correlations between dental wear and oral cavity characteristics: Mandibular torus, palatine torus, and oral exostoses

OBJECTIVE

This study evaluates the correlations amongst mandibular torus, palatine torus, oral exostoses to dental wear/loss and temporomandibular damage.

METHODS

The sample consists of 504 skulls from the Hamann-Todd Osteological Collection; 223 African American and 281 European Americans aged between 30 and 80 years. The sample was analyzed using Pearson's Chi-square for significance of sex, age, ancestry, and wear as well as the interactions between the demographic variables and the presence of mandibular torus, palatine torus and oral exostoses.

RESULTS

Wear was statistically significant by age and sex but not ancestry. The maxillary exostoses varied significantly by age, ancestry and wear but not sex. Mandibular torus frequencies varied significantly by wear, sex and ancestry. The palatine torus varied significantly across wear groups, sex and ancestry.

DISCUSSION

The etiology of nonmetric oral cavity characteristics, mandibular torus, palatine torus and oral exostosis, is complex. The degree to which traits' presence and expression is the result of genetic and environmental interactions is not fully understood. More than age, sex or ancestry, the degree of dental wear and tooth loss influences the presence and expression of the oral cavity traits. The sample can be characterized as the presence of exostoses in higher frequencies in young African American males with little tooth loss. Males of both ancestral groups with heavy wear have higher frequencies of mandibular tori than females. The palatine torus is more common in edentulous European American females.

Dental development and craniofacial morphology in school-age children

INTRODUCTION

The growth of the craniofacial complex is important for establishing a balanced relationship among the teeth, jaws, and other facial structures. However, there is still a lack of information about craniofacial parameters that are affected by the rate of dental development. The aim of this study was to investigate the association between dental development and craniofacial morphology in school-age children.

METHODS

This study was embedded in the Generation R Study, Rotterdam, The Netherlands. In 3,896 children aged 8 to 11 years, dental development was assessed from panoramic radiographs and craniofacial morphology was assessed by combining cephalometric parameters into 9 uncorrelated principal components, each representing a distinct skeletal or dental craniofacial pattern. The statistical analysis was performed using linear and nonlinear regression model.

RESULTS

Dental development was positively associated with the bimaxillary growth (β = 0.04; 95% CI 0.01 to 0.08). Children with above-average dental development had a tendency toward Class II jaw relationship (β = -0.08; 95% CI -0.13 to -0.04). Regarding dental parameters, the proclination increased for incisors and lips with advanced dental development (β = 0.15 [95% CI 0.10 to 0.19] and β = 0.13 [95% CI 0.09 to 0.17], respectively), but the incisor proclination remained more pronounced in children that had above-average dental development.

CONCLUSIONS

The findings of this large population-based study show that dental development is associated with specific dental and skeletal cephalometric characteristics in school-age children. Further longitudinal studies are necessary to confirm the observed effects over time.

Do Exostoses Correlate with Contact Disfunctions? A Case Study of a Maxillary Exostosis

A maxillary exostosis is a benign overgrowth of bone that occurs on the outer or facial surface of the maxilla and is usually located near the premolar or molar teeth. This paper investigates the correlation between the presence and growth of jaw exostoses and the oral mechanics of contact. For this purpose, a case study of an upper jawbone exostosis of a female patient was considered. 3D models of the patient’s cranial bones were extracted from 2D computerized tomography (CT) data and were analyzed by proper software. A contact congruence evaluation based on the Winkler contact model was performed, and results were presented in terms of indentation maps and load distributions. Results were correlated with the theory of bone remodelling by Wolff.

Dietary material properties shape cranial suture morphology in the mouse calvarium

Cranial sutures are fibrous connective tissue articulations found between intramembranous bones of the vertebrate cranium. Growth and remodeling of these tissues is partially regulated by biomechanical loading patterns that include stresses related to chewing. Advances in oral processing structure and function of the cranium that enabled mammalian-style chewing is commonly tied to the origins and evolution of this group. To what degree masticatory overuse or underuse shapes the complexity and ossification around these articulations can be predicted based on prior experimental and comparative work. Here, we report on a mouse model system that has been used to experimentally manipulate dietary material properties in order to investigate cranial suture morphology. Experimental groups were fed diets of contrasting material properties. A masticatory overuse group was fed pelleted rodent chow, nuts with shells, and given access to cotton bedding squares. An underuse group was deprived of cotton bedding as well as diverse textured food, and instead received gelatinized food continuously. Animals were raised from weaning to adulthood on these diets, and sagittal, coronal and lambdoid suture morphology was compared between groups. Predicted intergroup variation was observed in mandibular corpus size and calvarial suture morphology, suggesting that masticatory overuse is associated with jaw and suture growth. The anterior region of the sagittal suture where it intersects with the coronal suture (bregma) showed no effect from the experiment. The posterior sagittal suture where it intersects with the lambdoid sutures (lambda) was more complex in the overuse group. In other words, the posterior calvarium was responsive to dietary material property demands while the anterior calvarium was not. This probably resulted from the different strain magnitudes and/or strain frequencies that occurred during overuse diets with diverse material properties as compared with underuse diets deprived of such enrichment. This work highlights the contrasting pattern of the sutural response to loading differences within the calvarium as a result of diet.

Gravitational forces, negative pressure and facial structure in the genesis of airway dysfunction during sleep: a review of the paradigm

The recent and distant literature has extensive discussion of how sleep apnea, adeno-tonsillar growth, and facial structural deformity are related. Conventionally, the order of cause and effect is as follows: (1) Inflammatory/infectious process→tonsillar/adenoid tissue growth→(2) airway obstruction and mouth breathing/Obstructive Sleep Apnea (OSA)→(3) altered facial structure (adenoid facies). Using this same reasoning, adenotonsillectomy is the first line of treatment in the prevention of structural abnormalities. However, through a lifetime of clinical research Christian Guilleminault and his colleagues have challenged this paradigm. Through multiple articles and studies, Guilleminault et al., teach that even slight (subclinical) facial structure/muscle tone variations may be the inciting event triggering mouth-breathing and the eventual adenotonsillar growth in most patients. Essentially, this is the reverse of the conventional paradigms. Initial treatments therefore shift from simplified removal of inflammatory tissue to limiting mouth-breathing via musculo-skeletal modification. The purpose of this paper is to synthesize and analyze the recent (and distant) relevant literature to provide support for, and provide a potential anatomic mechanism for Guilleminault et al.'s paradigm-questioning clinical observations.

Presurgical Preparation of Infants With Unilateral Cleft Lip and Palate: The SAC-PP-MR Innovative Technique

In this article, we demonstrate an effective, cheap, and fast way to shape the nasal alar cartilage in patients with unilateral cleft lip and palate. This technique straightens the vomer and brings the philtrum, columella, premaxilla, and the maxillary frenum to the midsagittal plane, while the alveolar ridges are shaped and positioned. This reduces the lip and palatal cleft to zero even in a 4-week period.

Relationship between dental age, chronological age and cervical vertebral maturation in children and adolescents from Bucaramanga, Colombia

Objective: To determine the relationship between chronological age and dental age using Demirjian’s method and Baccetti’s method of cervical vertebral maturation in radiographs of children and adolescents aged 5 to 16 years in the city of Bucaramanga, Colombia. Methods: An analytical observational cross-sectional study was performed in 1385 cephalometric and panoramic radiographs of 775 females and 610 males. Sex, dental age according to the Demirjian’s method, chronological age and degree of maturation of the cervical vertebrae according to Baccetti’s method were analyzed. The univariate analysis included the calculation of measures of central tendency for quantitative variables, and frequencies and proportions for qualitative variables. Spearman correlation coefficients were calculated in the bivariate analysis. In the multivariate analysis a multiple linear regression was performed. A value of p<0.05 was considered statistically significant. Results: The mean chronological age was 10.8±3.3 years [Median: 11; 95% CI:10.6-10.6]. There was no statistically significant difference according to sex (p=0.3409). The mean of the differences between dental age and chronological age was 0.60±1.44 years. There was a strong and positive correlation between dental age and chronological age with each stage of maturation. Females reached skeletal maturity at an earlier age. Conclusions: Chronological age shows a direct and positive relationship with dental age and stages of skeletal maturation in a Colombian population.

Skeletal dimensions as predictors for the shape of the nose in a South African sample: A cone-beam computed tomography (CBCT) study

The profile of the nose is an important feature for facial approximations. Although several manual and semi-automated prediction guidelines exist for estimating the shape of the nose, the reliability and applicability of these methods to South Africans groups are unknown. The aim of this study was to predict the displacements of capulometric landmarks from hard-tissue planes to facilitate nasal soft-tissue reconstruction in a South African sample. Cone beam computed tomography (CBCT) scans of 120 adult South Africans were selected from the Oral and Dental Hospital, University of Pretoria, South Africa. Measurements involving craniometric and capulometric landmarks of the nose were obtained as plane-to-plane distances. Correlation coefficients between hard- and soft-tissue measurements were determined, and regression equations computed to assist in the prediction of the most probable shape and size of the nose. All hard- and soft-tissue measurements appeared significantly different between groups, except for the distance between the pronasale and nasion in the transverse plane and for the distance between the alare and the nasion in the coronal plane. The nasal height, nasal bone length and the nasal bone projection were significant predictors of the pronasale, subnasale and alare positions. More precisely, the nasal height and the nasal bone length were significant predictors of the pronasale position in both groups. Nasal bone projection was only useful for predicting shape in white South Africans. The variation in the skeletal predictors of the external shape of the nose noted between black and white South Africans and the results of the cross-validation testing emphasize the need for population specific guidelines.

Implications of Vertebrate Craniodental Evo-Devo for Human Oral Health

Highly processed diets eaten by postindustrial modern human populations coincide with higher frequencies of third molar impaction, malocclusion, and temporomandibular joint disorders that affect millions of people worldwide each year. Current treatments address symptoms, not causes, because the multifactorial etiologies of these three concerns mask which factors incline certain people to malocclusion, impaction, and/or joint issues. Deep scientific curiosity about the origins of jaws and dentitions continues to yield rich insights about the developmental genetic mechanisms that underpin healthy craniodental morphogenesis and integration. Mounting evidence from evolution and development (Evo-Devo) studies suggests that function is another mechanism important to healthy craniodental integration and fit. Starting as early as weaning, softer diets and thus lower bite forces appear to relax or disrupt integration of oral tissues, alter development and growth, and catalyze impaction, malocclusion, and jaw joint disorders. How developing oral tissues respond to bite forces remains poorly understood, but biomechanical feedback seems to alter balances of local bone resorption and deposition at the tooth-bone interface as well as affect tempos and amounts of facial outgrowth. Also, behavioral changes in jaw function and parafunction contribute to degeneration and pain in joint articular cartilages and masticatory muscles. The developmental genetic contribution to craniodental misfits and disorders is undeniable but still unclear; however, at present, human diet and jaw function remain important and much more actionable clinical targets. New Evo-Devo studies are needed to explain how function interfaces with craniodental phenotypic plasticity, variation, and evolvability to yield a spectrum of healthy and mismatched dentitions and jaws.

Evolving concepts of heredity and genetics in orthodontics

The field of genetics emerged from the study of heredity early in the 20th century. Since that time, genetics has progressed through a series of defined eras based on a number of major conceptual and technical advances. Orthodontics also progressed through a series of conceptual stages over the past 100 years based in part on the ongoing and often circular debate about the relative importance of heredity (nature) and the local environment (nurture) in the etiology and treatment of malocclusion and dentofacial deformities. During the past 20 years, significant advancements in understanding the genomic basis of craniofacial development and the gene variants associated with dentofacial deformities have resulted in a convergence of the principles and concepts in genetics and in orthodontics that will lead to significant advancement of orthodontic treatments. Fundamental concepts from genetics and applied translational research in orthodontics provide a foundation for a new emphasis on precision orthodontics, which will establish a modern genomic basis for major improvements in the treatment of malocclusion and dentofacial deformities as well as many other areas of concern to orthodontists through the assessment of gene variants on a patient-by-patient basis.

Postnatal changes in the growth dynamics of the human face revealed from bone modelling patterns

Human skull morphology results from complex processes that involve the coordinated growth and interaction of its skeletal components to keep a functional and structural balance. Previous histological works have studied the growth of different craniofacial regions and their relationship to functional spaces in humans up to 14 years old. Nevertheless, how the growth dynamics of the facial skeleton and the mandible are related and how this relationship changes through the late ontogeny remain poorly understood. To approach these two questions, we have compared the bone modelling activities of the craniofacial skeleton from a sample of subadult and adult humans. In this study, we have established for the first time the bone modelling pattern of the face and the mandible from adult humans. Our analyses reveal a patchy distribution of the bone modelling fields (overemphasized by the presence of surface islands with no histological information) reflecting the complex growth dynamics associated to the individual morphology. Subadult and adult specimens show important differences in the bone modelling patterns of the anterior region of the facial skeleton and the posterior region of the mandible. These differences indicate developmental changes in the growth directions of the whole craniofacial complex, from a predominantly downward growth in subadults that turns to a forward growth observed in the adult craniofacial skeleton. We hypothesize that these ontogenetic changes would respond to the physiological and physical requirements to enlarge the oral and nasal cavities once maturation of the brain and the closure of the cranial sutures have taken place during craniofacial development.

Facial skeletal trauma in the growing patient

The management of pediatric craniomaxillofacial trauma requires the additional dimension of understanding growth and development. The surgeon must appreciate the considerable influence of the soft tissue envelope and promote function when possible. Children heal well but with an exuberant tissue response that may contribute to greater scarring, therefore, careful and prudent attention given to meticulous soft tissue repair and support is critical. Support must also be given and sought from the family of the injured child. Follow-up management of children must continue to ensure that the growth of the craniomaxillofacial skeleton continues within the normal parameters of development.

Effects of interceptive orthodontics on orbicular muscle activity: a surface electromyographic study in children

The purpose of this study was to assess by surface electromyography (sEMG) the changes in upper and lower orbicular oris (OO) muscles produced by a preformed functional device in subjects with Class II, division 1 malocclusion, deep bite, and labial incompetence. Twenty-eight subjects were selected: 13 subjects (mean age 9 ± 1.5 years) with Class II malocclusion, deep bite, and labial incompetence were treated with a preformed functional device, while 15 subjects (mean age 9.5 ± 0.8 years) with normal occlusion were used as control. Inclusion criteria for both groups were: presence of mixed dentition, no previous orthodontic treatment, and absence of speech disturbance. sEMG recordings were taken at the time of the first visit (T0), and after 3 (T1) and 6 months (T2) for the treated group, and at T0 and T2 for the control group. The sEMG recording was performed at rest, and while kissing, swallowing, opening the mouth, clenching the teeth, and during protrusion of the mandible, by placing electrodes at the area of muscle contraction. At T0, except during swallowing, the treated group always showed a lower sEMG activity of the lower OO muscle with respect to the control group, with significant differences at rest and during mandibular protrusion (p<0.05). In the treated group, a significant increase in muscle tone was observed for the lower OO muscle from T0 to T1, but only at rest. The upper OO muscle showed a significant increase during the protrusion of the mandible from T1 to T2. No significant change was observed in the control group during the follow-up. Muscular contractility of treated patients at T2 reached the same values as that of the control group at T2. Interceptive orthodontics seems to improve the form and function of the orofacial muscle structure. Improvement in muscle contraction after treatment was demonstrated by sEMG.

The influence of masticatory hypofunction on developing rat craniofacial structure

The purpose of this study was to use botulinum neurotoxin type A (BoNT/A) selectively to evaluate the influence of localized masticatory atrophy and paresis on craniofacial growth and development. 60 growing rats, 4 weeks old, weighing approximately 120g, were randomly divided according as follows (Long-Evans, N=15 per group): I (Mb+Tns); II (Mns+Tb); III (Mb+Tb); IV (Mns+Tns), where Mb or Tb is the BoNT/A-injected masseter or temporalis muscles (1.0U/muscle, 2.5ml) and Mns or Tns is the saline-injected muscles (2.5ml). After 7 weeks, the mature rats were killed, the muscles dissected and mean muscle mass recorded. Anthropometric cranial, maxillary and mandibular measurements were taken from the dried skulls. Changes in animal weight during the growth period were not statistically significant. The mean masticatory muscle mass was smaller for the BoNT/A-injected muscles of Mb and Tb. Anthropometric measurements of bony structures inserted by masseter and temporalis muscles revealed a significant treatment effect. The measurements showed a facial morphology typical of a dolichofacial profile: short upper face accompanied by a long lower face with an extended mandibular length and ramus height and constricted bicoronoidal and bigonial widths. The results suggest that induction of localized masticatory muscle atrophy with BoNT/A alters craniofacial growth and development.

Brain phenotypes in two FGFR2 mouse models for Apert syndrome

Apert syndrome (AS) is one of at least nine disorders considered members of the fibroblast growth factor receptor (FGFR) -1, -2, and -3-related craniosynostosis syndromes. Nearly 100% of individuals diagnosed with AS carry one of two neighboring mutations on Fgfr2. The cranial phenotype associated with these two mutations includes coronal suture synostosis, either unilateral (unicoronal synostosis) or bilateral (bicoronal synostosis). Brain dysmorphology associated with AS is thought to be secondary to cranial vault or base alterations, but the variation in brain phenotypes within Apert syndrome is unexplained. Here, we present novel three-dimensional data on brain phenotypes of inbred mice at postnatal day 0 each carrying one of the two Fgfr2 mutations associated with AS. Our data suggest that the brain is primarily affected, rather than secondarily responding to skull dysmorphogenesis. Our hypothesis is that the skull and brain are both primarily affected in craniosynostosis and that shared phenogenetic developmental processes affect both tissues in craniosynostosis of Apert syndrome.