The primary role of functional matrices in facial growth

The bone-muscle unit: from mechanical coupling to soluble factors-mediated signaling

Skeletal muscles (SKM) and bones form a morpho-functional unit, interconnected throughout life primarily through biomechanical coupling. This relationship serves as a key reciprocal stimulus, but they also interact via various hormones, such as sex steroids, growth hormone-insulin-like growth factor 1 (GH-IGF1) axis hormones, and adipokines like leptin and adiponectin. Additionally, myokines (released by muscles) and osteokines (released by bones) facilitate dense crosstalk, influencing each other's activity. Key myokines include interleukin (IL)-6, IL-7, IL-15, and myostatin, while osteocalcin (OC) and sclerostin are crucial bone-derived mediators affecting SKM cells. Moreover, miRNAs act as endocrine-like regulators, contributing to a complex network. This review covers the current understanding of bone-muscle crosstalk, which is essential for grasping the musculoskeletal apparatus's role in disease pathogenesis and may inform therapeutic development.

Open Mouth Posture Syndrome (OMPS): Classification

Objectives: This narrative review aims to redefine Open Mouth Posture Syndrome (OMPS) as a multifactorial condition with overlapping symptoms and a cyclical pathophysiology. A novel classification system for OMPS subtypes is proposed to standardize research approaches and enhance clinical understanding. Methods: An interdisciplinary literature review was conducted, focusing on structural, functional, and adaptive mechanisms underlying OMPS. Subtype definitions were refined based on recent findings. Results: OMPS is categorized into five subtypes: Obstructive, Habitual, Anatomical, Sleep-Disordered Breathing, and Tongue-Related Pathologies. These subtypes share interconnected etiologies and manifestations, contributing to a feedback loop that complicates diagnosis and management. Conclusions: This classification system lays the foundation for future research and clinical protocols, emphasizing the need for a systematic approach to understanding OMPS.

Cranial vault thickness, its internal organization, and its relationship with endocranial shape in Neanderthals and modern humans

Compared to the more elongated crania of Neanderthals, modern humans have a rounder, more globular cranial vault. The factors contributing to this globular cranial and endocranial morphology remain poorly understood. Cranial vault thickness (CVT) plays a role in shaping the braincase. It has been proposed that CVT variation in hominins reflects distinct stimuli influencing the cranial vault layers to different degrees. We aim to determine to what extent CVT differences could explain the well-documented endocranial shape differences between modern humans and Neanderthals. Additionally, we quantify the contributions of each cranial vault layer-the inner and outer tables and the diploë-to elucidate the processes driving CVT variation. We analyzed crania from seven Neanderthals and 75 modern humans using a ray casting method to measure cortical, diploic, and overall CVT. We generated morphometric maps of thickness distributions for each cranial vault layer. We then quantified the endocranial shape using geometric morphometrics and analyzed its relationship with CVT using two-block partial least squares analysis and regression models. Our findings reveal that Neanderthals generally have greater CVT and thicker layers of the cranial vault than modern humans. However, their ranges overlap with those of modern humans. The thicker vaults of Neanderthals are primarily driven by the diploic layer, with notable differences in thickness distribution patterns. Additionally, the inner and outer cortical tables exhibit distinct thickness distribution patterns between the two groups. Structural differences between the parietal bones of Neanderthals and modern humans are particularly pronounced. Furthermore, we observed a unique correspondence between CVT and endocranial shape in modern humans, which is not shared by Neanderthals.

Overcoming three-dimensional challenges through objective decomposition and virtual-digital design: A multidisciplinary case on hypodontia treatment

A 15-year-old female sought multidisciplinary treatment for hypodontia, three-dimensional problems, deep overbite, multiple occlusal interferences, and collapse of the occlusion. Through virtual-digital design with objective decomposition, this patient underwent five steps of orthodontic treatment under the guidelines of the principles: removal of occlusal restriction is a prerequisite; transverse problems are solved first; then sagittal problems; and vertical correction runs through the treatment. After orthodontic and prosthetic treatment, aesthetic appearance and functional occlusion were achieved. In complex multidisciplinary cases with three-dimensional problems, which makes it difficult to formulate the final goal, virtual-digital design under objective composition and standardized comprehensive principle are effective and necessary.

Correlation Between Facial Asymmetry and Maxillary Sinus Size or Volume Using Dental Cone-Beam Computed Tomography Images

Objectives This study investigated correlations between facial asymmetry and left-right differences in maxillary sinus size and volume, as well as their relationships with skeletal morphology. Methods The participants were 154 Japanese adults (56 men, 98 women) aged 18 to 38 years (mean age, 24.1 ± 5.3 years). Cone-beam computed tomography (CBCT) images were analyzed using InVivo™ 6 software (Anatomage, Inc., San Jose, CA, USA). Facial asymmetry was assessed at six landmarks: orbitale, condylion, and gonion (all bilateral); anterior nasal spine; deepest point in bony concavity (B point); and menton (at midline). Maxillary sinus height, width, length, and volume were measured. Participants were classified into skeletal classes (I, II, III) and vertical growth patterns (horizontal, average, vertical). Spearman's rank correlation coefficient was used to assess the relationships of these six facial asymmetry landmarks with differences in maxillary sinus linear measurements and volume. Results The facial asymmetry index was positively correlated with maxillary sinus length in the condylion region and height in the gonion region. As left-sided facial deviation increased, the right maxillary sinus became larger; conversely, as right-sided facial deviation increased, the left maxillary sinus became larger. Thus, the maxillary sinus on the nondeviated side tends to be larger. Vertical facial growth patterns showed greater maxillary sinus height and volume in the vertical growth group than in the average growth group. Conclusions Asymmetry in specific facial regions may be associated with region-specific variations in maxillary sinus morphology, and vertical skeletal patterns may influence maxillary sinus development. These findings offer insights into the relationship between facial asymmetry and maxillary sinus structure.

Influence of genetic and environmental factors on transverse growth

OBJECTIVES

The aim of the study was to determine the genetic and environmental effects on transverse growth of craniofacial structures, within and between identical and fraternal twins.

METHODS

The sample consisted of 142 children in total, divided into 29 pairs of monozygotic twins, 42 pairs of dizygotic twins, and 1 set of dizygotic triplets. Postero-anterior cephalometric radiographs were taken at the ages of 9, 12, and 15 years. Intercanine width, maxillary width, mandibular width, nasal width, and facial width variables were measured. The genetic and environmental components of variance were analyzed with structural equation modeling for multilevel mixed effects.

RESULTS

Intercanine width was initially mainly characterized by a moderate genetic component at 9 years (53%), with environmental influence increasing at age 12 (36%) and peaking at 15 years (84%). Maxillary width was under strong genetic influence at 9 years (70%), with genetic influence remaining strong up to 15 years (73%). Mandibular width was under additive genetic influence at 9 years (76%), with dominant genetic influence remaining high at 15 years (81%). Nasal width was under strong additive genetic influence at 9 years (69%) but switched to increased environmental influence at 15 years (59%). Finally, facial width had a moderate genetic influence at 9 years (66%), which increased at 15 years (90%).

LIMITATIONS

This study included patients of European descent, which may limit the generalizability of the findings to other ethnic groups.

CONCLUSIONS

Although monozygotic and dizygotic twins share at least part of their genetic material, environmental factors accounted for about 10%-84% of variability at various ages, with intercanine width being most affected.

Variation of chin morphology and mandibular incisor length in different facial divergence patterns: New insights from CBCT records

AIM

Evaluate constitutional differences in chin morphology and volume, and mandibular tooth size, between different facial divergence patterns.

MATERIALS AND METHODS

The sample consisted of 284 pretreatment cone beam computed tomography (CBCT) images of growing and non-growing patients who were stratified into 4 groups based on mandibular plane inclination to cranial base (SN) angle. Linear and angular measurements were made on the lateral CBCT images: mandibular lateral incisor crown (I-C) total (I-A) lengths, the distances between point D (centre of symphysis) and both incisor apex (D-A) and menton (D-Me) and between cemento-enamel junction and menton (CEJ-Me); chin width at the level of the central incisor apex (CWA) and point D (CWD); and the angles of the anterior and posterior symphyseal slopes. The volume of the symphysis was measured using a specialized 3D imaging software. Group differences and associations between parameters were gauged through the three-way ANOVA analysis.

RESULTS

I-C, I-A, D-A, D-Me and CEJ-Me were greater in the hyperdivergent group (p < .001). CWA and CWD were wider in the hypodivergent group (p = .003). Volume of the chin and inter-slope angles were similar in all groups (p > .05). The anterior slope angle decreased with hyperdivegence (p < .005) in opposite pattern to the posterior slope angle (p < .005).

CONCLUSIONS

Shape differences in mandibular symphysis were observed between opposite divergence patterns. Mandibular incisors were longer with hyperdivergence and shorter with hypodivergence. However, chin volumes were similar across divergence groups. These findings underline the role of genetic and environmental factors that impact facial growth.

Expert consensus on orthodontic treatment of protrusive facial deformities

Protrusive facial deformities, characterized by the forward displacement of the teeth and/or jaws beyond the normal range, affect a considerable portion of the population. The manifestations and morphological mechanisms of protrusive facial deformities are complex and diverse, requiring orthodontists to possess a high level of theoretical knowledge and practical experience in the relevant orthodontic field. To further optimize the correction of protrusive facial deformities, this consensus proposes that the morphological mechanisms and diagnosis of protrusive facial deformities should be analyzed and judged from multiple dimensions and factors to accurately formulate treatment plans. It emphasizes the use of orthodontic strategies, including jaw growth modification, tooth extraction or non-extraction for anterior teeth retraction, and maxillofacial vertical control. These strategies aim to reduce anterior teeth and lip protrusion, increase chin prominence, harmonize nasolabial and chin-lip relationships, and improve the facial profile of patients with protrusive facial deformities. For severe skeletal protrusive facial deformities, orthodontic-orthognathic combined treatment may be suggested. This consensus summarizes the theoretical knowledge and clinical experience of numerous renowned oral experts nationwide, offering reference strategies for the correction of protrusive facial deformities.

Near-Normalized Maxillomandibular Relationship and Upper Airway in Infants with Robin Sequence Treated with Stanford Orthodontic Airway Plate: Computed Tomography Study

OBJECTIVE

To assess craniofacial and upper airway growth in infants with Robin sequence (RS) during the 1st year of life when their severe upper airway obstruction was treated non-surgically with the Stanford orthodontic airway plate treatment program (SOAP).

DESIGN

Retrospective longitudinal cohort study comparing SOAP-treated infants with RS (treatment group) with age-matched healthy controls (HC) using computed tomography (CT).

SETTING

Single tertiary referral hospital.

PATIENTS

Twelve SOAP-treated infants with RS.

INTERVENTIONS

SOAP.

MAIN OUTCOME MEASURES

Craniofacial skeletal cephalometric parameters and three-dimensional airway metrics.

RESULTS

No infants required mandibular distraction or tracheostomy surgery after SOAP. The pre-treatment CT was acquired at the mean age (±SD) of 1.3 months (±0.7). The treatment lasted for 4.8 months (±0.9). Post-treatment CT was acquired at 12.9 months (±2.3) of age. The pre-treatment obstructive apnea hypopnea index decreased from 29.21 events/hour (±14.80) to 4.11 events/hour (±2.21) at post-treatment. The total mandibular length increased from 40.58 mm (±2.98) to 62.15 mm (±2.77) at post-treatment (p < 0.001) resulting in the growth velocity of 51.02% (±11.20) or 20.52 mm (±3.95) per year. The maxillary and mandibular lengths of the treatment group at post-treatment were shorter than those of HC although the maxillomandibular relationship was not different (p = 0.618). The upper airway volume and minimal cross-sectional area were also not different (p = 0.083, p = 0.254, respectively).

CONCLUSIONS

The maxillomandibular relationship and upper airway of the SOAP-treated infants with RS were near-normalized at post-treatment, comparable to age-matched healthy infants.

Association between dental agenesis and facial morphology. A cross-sectional study in France

PURPOSE

Knowing the features of dental evolution and facial morphology, marked by an increase in the prevalence of agenesis and a tendency towards verticalization of the face, the main objective of this cross-sectional observational study was to assess the correlation between the occurrence of agenesis (of 3rd molars or other teeth) and facial morphology in the French population.

METHODS

The study was conducted at the University Hospital of Rennes, France, from June 2022 to October 2022. Patients aged 12-18 years who underwent a global orthodontic assessment were included. Data collected from medical examinations, panoramic, anteroposterior, and lateral x-rays were analyzed for cephalometric and dental features. The association between morphological parameters and agenesis of wisdom teeth or other teeth was assessed by univariate and multivariate analysis.

RESULTS

The study included 259 patients, of whom 89 presented agenesis. Logistic regression analyses identified several morphological parameters associated with agenesis. In the multivariate model, a negative correlation was found between tooth agenesis and FMA (OR = 0.85; p < 0. 001), facial axis (OR = 0.92; p = 0.040), and a positive one with SNB (OR = 1.17; p = 0.023), ANS-Xi-Pm (OR = 1.12; p = 0.013).

CONCLUSION

This study highlights the correlation between agenesis occurrence and specific cephalometric parameters in the French population. The findings suggest that transverse constriction of the maxilla, facial divergence, and anterior projection of the chin symphysis are associated with agenesis. Trial registration number: Opinion n°22.103, dated 06.04.2022.

Effects of gum chewing training on occlusal force, masseter muscle thickness and mandibular shape: A randomised controlled clinical trial

BACKGROUND

Masticatory muscle training by chewing gum can be performed easily and improve masticatory muscle function and strength. However, increased masticatory muscle activity and function may alter the mandibular shape.

OBJECTIVE

We aimed to investigate the effects of gum chewing training on the occlusal force, masseter muscle thickness (MMT) and mandibular shape in healthy adults.

METHODS

We conducted a prospective randomised controlled trial from January 2020 to September 2020 at the Yonsei University College of Dentistry. Fifty-eight participants were randomly assigned to the training and control groups. The training group chewed gum three times a day for 6 months, while the control group received no training. Changes in the maximum occlusal force and MMT were evaluated at baseline and after 1, 3 and 6 months. Changes in the mandibular shape were evaluated at baseline and after 6 months.

RESULTS

The mean maximum occlusal force of the training group at 3 months was significantly higher than that at baseline, which was also significantly different from that in the control group (p < .001). As the maximum occlusal force increased, the occlusal contact area also increased (p = .020). There was no statistically significant difference in MMT or mandibular shape compared to the baseline.

CONCLUSION

Mastication training using gum increases maximum occlusal force due to an increase in occlusal contact area but has no effect on MMT or mandibular shape.

Age-group-specific associations between adenoid/tonsillar hypertrophy and craniofacial features

BACKGROUND

Age plays an important role in the association between adenotonsillar hypertrophy and craniofacial morphology. This study aimed to analyse the association of adenoid and tonsillar hypertrophy with craniofacial features in different age groups.

METHODS

Lateral cephalograms were obtained from 942 patients aged 6-15 years (433 boys, 509 girls). They were divided into three age groups: 6-9 years (n = 189), 9-12 years (n = 383), and 12-15 years (n = 370). According to the different sites of pharyngeal obstruction, they were classified as control group (CG), adenoid hypertrophy group (AG), tonsillar hypertrophy group (TG) and adenotonsillar hypertrophy group (ATG). Cephalometric measurements were performed on each enrolled participant. Comparisons between groups and correlations between these cephalometric variables and obstruction sites were evaluated.

RESULTS

At 6-9 years of age, ATG and TG correlated with increased mandibular height (B = 2.2, p = 0.029; B = 2.6, p = 0.042, respectively). At the age of 9-12 years, AG showed a steep growth direction (B = 1.5, p = 0.002), TG showed a higher probability of Class III skeletal pattern (smaller SNB, ANB and SGn/FH, larger Go-Me) and ATG manifested a higher proportion of Class III skeletal pattern. At 12-15 years of age, there was no significant association between cephalometric measurements and pharyngeal lymphoid tissue enlargement.

CONCLUSIONS

Children with isolated adenoid hypertrophy have a vertical growth direction at 9-12 years of age. Isolated adenoid hypertrophy correlated with longer mandibular body, more anterior mandible and horizontal skeletal Class III pattern at 6-12 years. Combination of obstructive adenoids and tonsils manifested similarly to children with isolated tonsil hypertrophy.

A cephalometric analysis of the antegonial notch in relation to the direction of mandibular growth

Masticatory muscle forces influence craniofacial morphology development. The antegonial notch (Notch) is a bony concavity on the inferior border of the mandible. Considering the Notch is located anteriorly to the insertion of the masseter muscle and varies among individuals, we hypothesised that these muscles influence the formation of the Notch. Therefore, this study aimed to investigate the correlation between mandible morphology and Notch formation. Sixty Japanese patients who visited the Department of Orthodontics at our university hospital were retrospectively evaluated. Morphological and morphometric analyses of the Notch and related craniofacial parameters were conducted using lateral cephalograms taken at the patients' initial visits. Standard values for the Notch area and depth were determined, and the morphology of the Notch and mandible was analysed using Spearman's rank correlation coefficient (p < 0.05). The mean Notch area and depth was 78.71 ± 36.54 mm2 and 3.11 ± 1.09 mm, respectively. The Notch area was significantly correlated with ramus inclination (p = 0.044, r = 0.261) and with the Y-axis (p = 0.039, r = 0.267). This study indicated that both the masticatory muscles and mandibular growth could contribute to the Notch formation.

3D evaluation of cranial and dentofacial morphological differences between individuals with mouth breathing and nasal breathing

INTRODUCTION

The present study aimed to identify the morphological differences in cranial and dentofacial structures between individuals with mouth-breathing and nasal-breathing.

MATERIALS AND METHODS

The study included 120 individuals, 60 each in the nasal breathing (NB) and mouth breathing (MB) groups. 3D stereophotogrammetry, lateral cephalometric radiographs, and intraoral examination results were recorded by the researchers to determine the morphological differences between the MB group and the NB group. The study utilized cephalometric radiographs for 2D hard tissue measurements and 3D stereophotogrammetric records for linear and angular measurements.

RESULTS

Statistically significant differences were found between the NB and MB groups' SNB angles (respectively, 79.3 ± 3.04, 76.6 ± 4.24, and p=0.002). Also, the NB group's SN-GoGn angle was lower than the MB group's (respectively, 31.5 ± 5.12, 36.0 ± 5.55, and p=0.002). Considering the Jarabak ratio, the NB group's Jarabak ratio was higher than the MB group (respectively,65.7 ± 4.16, 62.6 ± 4.10, and p=0.014). In 3D stereophotogrammetry measurements, increased Li-Me' was detected in the MB group than in NB group.

CONCLUSION

Mouth breathing results in significant morphological differences that affect the development of both soft tissues and skeletal structures. Orthodontists utilize these characteristic features observed in mouth-breathing anomalies for early diagnosis and consider referring their patients for medical treatment of mouth breathing.

Upper airway dimensions and craniofacial morphology: A correlation study using cone beam computed tomography

Objective

To determine the correlation between dentoskeletal parameters related to craniofacial morphology and the upper airway (UA) volume.

Methods

Cone-beam computed tomography images of 106 randomly selected orthodontic patients were analyzed using NemoFab Ortho software. The dentoskeletal variables assessed were anterior facial height (AFH), posterior facial height (PFH), PFH/AFH ratio, hyoid position, maxillary width (MW), and palatal depth. The UA volume (evaluation in anatomical regions and as a whole) was also assessed using the same software. We also evaluated potential differences in UA variables between age and sex groups. The correlation between the dentoskeletal parameters and UA volume was calculated using the Pearson correlation coefficient (R). Analysis of variance and Student's t test were performed to assess differences between age and sex for UA variables. Statistical analyses were performed using SPSS software (version 26 for Windows).

Results

This study found that PFH, AFH, and MW were the dentoskeletal parameters most strongly correlated with UA volume. However, the ANB angle did not show any significant correlation with UA volume. Additionally, differences in UA volumes were observed between age groups. Sex differences were found in both the "8-12" and "≥ 16" age groups for oropharyngeal and pharyngeal volumes.

Conclusions

In conclusion, our findings indicate a significant correlation between UA volume and dentoskeletal parameters, particularly those related to facial height and MW.

A physico-mechanical model of postnatal craniofacial growth in human

Our fundamental understanding of the physico-mechanical forces that drive the size and shape changes of the cranium during ontogeny are limited. Biomechanical models based on finite element method present a huge opportunity to address this critical gap in our knowledge. Here, we describe a validated computational framework to predict normal craniofacial growth. Our results demonstrated that this approach is capable of predicting the growth of calvaria, face, and skull base. We highlighted the crucial role of skull base in antero-posterior growth of the face and also demonstrated the contribution of the maxillary expansion to the dorsoventral growth of the face and its interplay with the orbits. These findings highlight the importance of physical interactions of different components of the craniofacial system. The computational framework described here serves as a powerful tool to study fundamental questions in developmental biology and to advance treatment of conditions affecting the craniofacial system such as craniosynostosis.

Association between adenotonsillar hypertrophy and dentofacial characteristics of children seeking for orthodontic treatment: A cross-sectional study

OBJECTIVE

To compare the dentofacial characteristics of children with and without adenoid and/or tonsillar hypertrophy.

METHODS

A consecutive sample of orthodontic patients aged 6-12 that took pre-treatment lateral cephalograms were included in this study. Those with history of previous orthodontic treatment, adenoidectomy or tonsillectomy, or craniofacial anomalies were excluded. The diagnosis of adenoid and tonsillar hypertrophy was based on Fujioka's and Baroni's methods, according to which the subjects were divided into four groups: the adenoid hypertrophy only (AHO) group; tonsillar hypertrophy only (THO) group; combined adenoid and tonsillar hypertrophy (AH+TH) group; and no adenoid or tonsillar hypertrophy (NH) group. Cephalograms were used for skeletal and dental measurement. Data were analyzed using one-way ANOVA, LSD post-hoc tests and Chi-square test.

RESULTS

A total of 598 patients were included. Compared with the NH group, the THO group had significantly larger SNB angle (P < 0.001), as well as significantly smaller ANB angle (P<0.001) and Wits value (P = 0.001). The U1-L1 angle of AHO group was significantly smaller than that in the NH group (P = 0.035). The proportion of adenoid hypertrophy in Class II patients was significantly higher than that in Class III patients (P = 0.001). The proportion of tonsillar hypertrophy in Class III patients was significantly higher than that in Class I patients (P < 0.001) and Class II patients (P < 0.001).

CONCLUSION

Over 80 % of children seeking orthodontic treatment had either adenoid or tonsillar hypertrophy. Children with adenoid hypertrophy tend to have skeletal Class II malocclusion, while those with tonsillar hypertrophy tend to have skeletal Class III malocclusion.

Novel prediction models for pharyngeal-airway volume based on the cranial-base and midsagittal cross-sectional area of the airway in the pharyngeal region: A cephalometric and magnetic resonance imaging study

OBJECTIVE

The objective of the study was to elucidate the association between cranial base (Bjork-Jarabak analysis), midsagittal cross-sectional area of the airway in the pharyngeal region (MCSA-PR) data and pharyngeal-airway volume (PAV) and develop a model that could help clinicians predict PAV using two-dimensional (2D) data (Bjork polygon and MCSA-PR).

MATERIALS AND METHODS

Pre-treatment lateral cephalometric radiographs and magnetic resonance imaging (MRI) scans of 82 women were categorized into three anteroposterior skeletal groups based on ANB angle: Class I (n = 29), 1.5° ≤ ANB≤5.1°; Class II (n = 26), ANB >5.1°; Class III (n = 27), ANB <1.5°. The Bjork polygon, MCSA-PR data from cephalograms and PAV data from MRI scans were examined. Intergroup comparisons were performed using the Kruskal-Wallis test and one-way analysis of variance (ANOVA), with pairwise comparisons conducted using the Bonferroni-corrected Mann-Whitney U-test for the Kruskal-Wallis test and Bonferroni-corrected multiple comparison test for one-way ANOVA. Forward multiple linear regression was used to create model equations for predicting PAV.

RESULTS

MCSA-PR and anterior (N-S) and posterior (S-Ar) cranial-base lengths were positively correlated with the PAV. We developed four models; three operated at the group level, and one encompassed the entire sample. Notably, all models could effectively explain the variance in the PAV data. The model for the Class I group was the strongest (adjusted R2 = 0.77).

CONCLUSION

Our findings indicate the remarkable potential of the MCSA-PR, N-S and Bjork sum angles (BSA) as predictors of the PAV and the relevance of 2D cephalometric and cranial-base parameters in predicting the three-dimensional (3D) pharyngeal-airway size.

Functional adaptation of the infant craniofacial system to mechanical loadings arising from masticatory forces

The morphology and biomechanics of infant crania undergo significant changes between the pre- and post-weaning phases due to increasing loading of the masticatory system. The aims of this study were to characterize the changes in muscle forces, bite forces and the pattern of mechanical strain and stress arising from the aforementioned forces across crania in the first 48 months of life using imaging and finite element methods. A total of 51 head computed tomography scans of normal individuals were collected and analysed from a larger database of 217 individuals. The estimated mean muscle forces of temporalis, masseter and medial pterygoid increase from 30.9 to 87.0 N, 25.6 to 69.6 N and 23.1 to 58.9 N, respectively (0-48 months). Maximum bite force increases from 90.5 to 184.2 N (3-48 months). There is a change in the pattern of strain and stress from the calvaria to the face during postnatal development. Overall, this study highlights the changes in the mechanics of the craniofacial system during normal development. It further raises questions as to how and what level of changes in the mechanical forces during the development can alter the morphology of the craniofacial system.

Internal structural analysis of the nasomaxillary complex in patients with skeletal class III asymmetry: A study on asymmetry patterns

OBJECTIVES

To investigate the internal structure of the nasomaxillary complex, including the maxillary sinus, nasal cavity and nasal septum according to the facial asymmetry pattern and to evaluate its correlation with external maxillomandibular asymmetry in Class III patients based on cone-beam computerized tomography (CBCT) images.

MATERIALS AND METHODS

Facial asymmetry was analysed in a total of 100 Class III patients aged 16 years or older using CBCT scans. Patients were categorized into subgroups based on asymmetry pattern. Measurements of the nasomaxillary complex were obtained from the CBCT scans, including the volume and width of the maxillary sinuses and nasal cavities on deviated and non-deviated sides, as well as the displacement of the nasal septum. Statistical analysis was performed to compare the internal nasomaxillary variables within and between groups, and regression analysis was conducted to evaluate the correlation between facial asymmetry and the internal nasomaxillary variables.

RESULTS

Group comparisons showed that there were no significant differences in the volume of the maxillary sinus and nasal cavity. However, the direction and extent of nasal septum deviation, as well as the width of the nasal cavity, varied depending on the maxillary asymmetry pattern. Regression analysis indicated a correlation between nasal septum deviation and the difference in maxillary height, while the difference in nasal cavity width was correlated with the difference in maxillary width.

CONCLUSION

A comprehensive evaluation of the internal nasal anatomy is vital for understanding the intricate relationship between nasal structure and maxillary growth.

Comparative cephalometric study of the airways between different ethnic groups with normal occlusion

OBJECTIVE

This study aimed to compare the nasopharynx and oropharynx airway dimensions of Caucasians, Blacks, Japanese, Japanese Brazilians, and Black Caucasians.

METHODS

A sample of 216 lateral radiographs of untreated young Brazilian subjects (mean age of 12.94 years; SD 0.88) were divided into five groups: Black Caucasian, Black, Caucasian, Japanese, and Japanese Brazilian. Lateral radiographs were used to measure the oropharynx (from the midpoint on the soft palate to the closest point on the anterior pharyngeal wall) and the nasopharynx (from the intersection of the posterior border of the tongue and the inferior border of the mandible to the closest point on the posterior pharyngeal wall). Analyses of variance (ANOVA) and Tukey's test were performed (p< 0.05).

RESULTS

The linear dimension of the oropharynx was similar among the different ethnic groups. Caucasian individuals presented a significantly greater linear dimension of the nasopharynx than Black Caucasian and Black individuals.

CONCLUSIONS

All the groups had similar buccopharyngeal values. However, Caucasian individuals had significantly higher values when compared to Black Caucasians and Black individuals.

Geospatial and Socioeconomic Disparities Influencing the Management of Craniosynostosis

BACKGROUND

Various social determinants of health have been described as predictors of clinical outcomes for the craniosynostosis population. However, literature lacks a granular depiction of socioeconomic factors that impact these outcomes, and little is known about the relationship between patients' proximity to the care center and management of the condition.

METHODS/DESIGN

This study retrospectively evaluated patients with craniosynostosis who presented to a tertiary children's hospital between 2000 and 2019. Outcomes of interest included age at presentation for surgery, incidence of reoperation, and length of follow-up. Patient addresses were geocoded and plotted on two separate shapefiles containing block group information within San Diego County. The shapefiles included percent parental educational attainment (bachelor's degree or higher) and median household income from 2010. The year 2010 was chosen for the shapefiles because it is the median year of data collection for this study. Multivariate linear, logistic, and polynomial regression models were used to analyze the relationship between geospatial and socioeconomic predictors and clinical outcomes.

RESULTS

There were 574 patients with craniosynostosis included in this study. The mean ± SD Haversine distance from the patient's home coordinates to the hospital coordinates was 107.2 ± 321.2 miles. After adjusting for the suture fused and insurance coverage, there was a significant positive correlation between distance to the hospital and age at index surgery (P = 0.018). There was no correlation between distance and incidence of reoperation (P = 0.266) or distance and duration of follow-up (P = 0.369). Using the same statistical adjustments, lower parental percent educational attainment and lower median household income correlated with older age at index surgery (P = 0.008 and P = 0.0066, respectively) but were not correlated with reoperation (P = 0.986 and P = 0.813, respectively) or duration of follow-up (P = 0.107 and P = 0.984, respectively).

CONCLUSIONS

The results offer evidence that living a greater distance from the hospital and socioeconomic disparities including parental education and median household income may serve as barriers to prompt recognition of diagnosis and timely care in this population. However, the geospatial and socioeconomic factors studied do not seem to hinder incidence of reoperation or length of follow-up, suggesting that, once care has been initiated, longitudinal outcomes may be less impacted.

Genetic and environmental impact on mandibular growth in mono- and dizygotic twins during adolescence: A retrospective cohort study

INTRODUCTION

This study aimed to discover the genetic and environmental factors that contribute to the mandibular development of untreated monozygotic and dizygotic twins.

MATERIAL AND METHODS

The sample, taken from the Forsyth Moorrees Twin Study, included 52 untreated monozygotic twins (36 male, 16 female) and 46 untreated dizygotic twins (23 male, 23 female). At the ages of 12 and 17, lateral cephalograms were collected and traced to assess total mandibular length, mandibular ramus length, mandibular corpus length, gonial angle, SNB, and bony chin prominence. The genetic and environmental components of variation were assessed using multilevel mixed-effects structural equation modelling.

RESULTS

At 12 years of age, high additive genetic influences were observed for total mandibular length (74%), gonial angle (76%), SNB (41%), and bony chin prominence (64%), whereas strong dominant genetic components were observed for corpus length (72%), and mandibular ramus length was under unique environment influence (54%). At 17 years of age, only total mandibular length (45%), ramus length (53%), gonial angle (76%), and bony chin prominence (68%) were under strong additive genetic control, while the remainder were under strong dominant genetic control.

CONCLUSIONS

Although monozygotic and dizygotic twins share at least a portion of their DNA, additive, dominant, or environmental components were discovered during adolescence. Nonetheless, by the age of 17, the majority of the mandibular traits are under either additive or dominant genetic impact.

Stepwise self-inflating hydrogel expansion for congenital anophthalmia and blind microphthalmia: Over 15 years' experience in China

BACKGROUND

Self-inflating hydrogel expanders have been used to treat anophthalmia and blind microphthalmia. This study aimed to investigate the long-term outcomes of treatment with self-inflating hydrogel expanders for congenital anophthalmia and blind microphthalmia.

METHODS

In this retrospective study, the medical records of 161 patients with anophthalmia and blind microphthalmia who underwent hydrogel expansion were reviewed. We measured the palpebral fissure height (PFH), palpebral fissure length (PFL), and distance between the inner canthal and mid-nasal line (ICMN) before and after surgery. Cox regression analysis was conducted to determine which variables were related to the implantation of spherical expanders following hemispherical expander implantation.

RESULTS

After treatment, the PFH and PFL increased significantly (p < 0.001). Complications including expander migration and extrusion occurred in 15 cases. Five patients needed enucleation or further dermis fat graft implantation because of insufficient expansion. The necessity for further spherical expansion was substantially related to a relative axial length (rAL) <0.5 (p = 0.007).

CONCLUSION

Self-inflating hydrogel expansion can significantly increase the lid fissure. The occurrence of complications is rare, and surgical intervention can effectively address them. Abnormal eyes with a rAL of less than 0.5 demonstrate a higher possibility of needing additional orbital expansion.

Association between bilateral condylar resorption and reduced volumes of the craniofacial skeleton and masticatory muscles in adult patients: A retrospective study

Objectives

This retrospective cohort study aimed to analyze volumes of craniomaxillofacial bone and masticatory muscles of young adults with bilateral idiopathic condylar resorption.

Methods

This was a retrospective cohort study of 84 adults with bilateral idiopathic condylar resorption (BCR) and 48 adults with normal temporal-mandibular joint (TMJ) matched for age and sex (mean age, 23.2 ± 3.6 years). The volumes of craniomaxillofacial bone and masticatory muscles, as well as intercondylar angle were measured. Unpaired t-tests and Pearson correlation tests were applied to analyze the data. Multivariable linear regression models were used to estimate the association between bilateral condylar volume and volumes of craniomaxillofacial bone and masticatory muscles adjusted for age, sex, and disc status.

Results

Compared to the control group, the BCR group displayed significant decreased volumes of craniomaxillofacial bone (p < 0.001), craniomaxillofacial bone without mandible (p < 0.001), mandible (p < 0.001), mandible without mandibular condylar process (p < 0.001), bilateral masseter muscle (p < 0.001) and bilateral temporalis muscle (p < 0.001), as well as the intercondylar angle (p < 0.001). These variables were significantly correlated to the volume of mandibular condylar process (0.5< r < 0.8; p < 0.001). By linear regression analyses, significant associations were found for the bilateral condylar volume with craniomaxillofacial bone volume and mandible bone volume.

Conclusions

Young adults with BCR displayed smaller volumes of craniomaxillofacial skeleton and masticatory muscles, and smaller intercondylar angle than the normal patients. The craniofacial musculoskeletal volume and intercondylar angle are associated with mandibular condylar process volume.

Role of the Growth Hormone Receptor (GHR) Gene in Skeletal Class II Malocclusion and Its Significant Influence on the Skeletal Facial Profile in Both the Sagittal and Vertical Dimensions: A Systematic Review

This systematic review aims to determine the role of the growth hormone receptor (GHR) gene in skeletal malocclusion and its significant influence on the growth of the maxilla and the mandible in both sagittal and vertical dimensions. A search of the electronic databases of PubMed, Google Scholar, and Cochrane up to and including the year 2023 was made. In addition to this, a hand search of orthodontic and dentofacial orthopaedic journals was carried out. This search included randomized control trials. The Mesh terms used were "skeletal class II malocclusion", "mandibular retrognathism", "sagittal malocclusion", "genetic expression", "genetic factors", "genetic study", "genetic polymorphism", and "single nucleotide polymorphism". The inclusion criteria included studies such as clinical trials and orthopaedic appliances in the presurgical phase. The exclusion criteria for the study were studies not in the English language, case reports, case series, and studies with irrelevant data. It has been cited in various literature that polymorphic variations of the GHR gene could cause variations in mandibular morphogenesis affecting both the mandibular body length and ramal height. However, its effects are quite variable and are based on different population groups. Polymorphism of the GHR gene can be considered a reliable indicator predicting variations in affecting the growth of the mandible with greater significance in affecting the vertical ramal height compared to the body length of the mandible. Its effects on the maxillary skeletal base are rather limited comparatively.

Impact of initial lip competence on the outcome of class II functional appliances therapy

OBJECTIVES

The aim of this prospective clinical study was to evaluate the impact of initial lip position on class II functional appliance therapy.

MATERIALS AND METHODS

In total, 34 class II division 1 patients (23 females, 19 males; mean age 12.4 ± 0.9 years) that met the inclusion criteria (> ½ class II molar relationship, overjet > 6 mm, ANB > 4°, neutral or horizontal growth pattern, cervical vertebral maturation stage (CVMS) II - III, mean wear-time > 10 h/day) were consecutively divided into two groups (lip incompetence (LI); lip competence (LC)). All patients were treated with the Sander bite jumping appliance (BJA). Wear time was microelectronically measured. Lateral cephalograms were taken at the beginning (T0) and after 1 year of treatment (T1). An untreated class II group served as a control (CG). Inter-group comparisons were determined with Mann-Whitney U tests for independent samples.

RESULTS

Significant skeletal treatment effects were found in both treated groups when compared to the CG with significantly more pronounced mandibular skeletal effects in the LI than in the LC group (mandibular base length p < 0.001, composite mandibular base length p < 0.001, condylar head growth p = 0.002, co-pg p < 0.00, go-pg p = 0.003, reduction of the ANB angle p = 0.009, and Wits appraisal p < 0.001).

CONCLUSION

The more pronounced mandibular effects in the LI group were composed of the functional orthopedic effect plus harmonization of the lip competence.

CLINICAL RELEVANCE

Functional harmonization of lip incompetence with BJA enhances mandibular growth stimulation. Lip incompetence seems to impede mandibular growth and its harmonization seems to be a preventive approach.

Post-burn deformity of the orofacial complex region: An Orthodontic approach

Image 1.

Insight into age-related changes of the human facial skeleton based on medieval European osteological collection

Aging changes in the facial skeleton are concentrated mostly in orbits, maxilla and mandible. The aim of this study was to analyze metric traits of the adult viscerocranium in a medieval sample from Cedynia (Poland, Central Europe) and confront the results with literature data for modern populations. It was assumed that diet-related greater biomechanical forces generated during mastication in medieval versus modern times led to slower rate of bone resorption with age. 3D models of the facial skeleton are created for 230 individuals, categorized into young, middle and old adults, and a subgroup of edentulous middle adults is distinguished. Orbits, piriform aperture, maxilla and mandible are measured using Geomagic Studio 12 and analyzed among age categories as well as dentate and edentulous subgroups. The values of the orbital and piriform aperture measurements tend to increase with age and reached statistical significance in males (right orbit height, left orbit width, piriform aperture surface area). In females, maxillary height significantly decrease at right first premolar and first molar, together with height of the right mandibular ramus. In edentulous individuals of both sexes the orbits are wider, and maxillary and mandibular heights are lower than in dentate individuals. This study reveals similar character and direction of the aging process of the facial skeleton in medieval and modern adults, however slower rate of resorptive changes is found in the former sample, which suggests, that diet-related biomechanical forces can influence intensification of the aging processes in the facial skeleton.

Quantification of global orbital shape variation

The complex anatomy of the orbit generates a complex orbital shape that can only be quantified approximatively by classic linear measurements such as maximum width and height. There is no global three-dimensional quantification of variations in orbital shape. The purpose of this study was to develop a method to quantify a global three-dimensional orbital shape variation in a healthy population and to test a series of explanatory factors. We investigated the hypotheses that orbital shape is related to gender(H1), orbital size(H2) and/or age(H3). Medical computed tomography(CT) images of 60 adult individuals were studied. The study sample consisted of 30 males and 30 females with a mean age of 25.1 years. Four anatomical landmarks and 140 semi-landmarks were measured on both positive and negative 3D reconstructed orbits and analyzed with geometric morphometrics. A principal component analysis(PCA) was computed to define a morphological space. Shape variation was visualized using vector distance maps and diagrams. The greatest variation was seen in the length of the superior orbital fissure. There was a gradient in terms of orbital shape ranging from short, wide orbits to tall, narrow orbits. The analysis did not highlight any significant age-, gender- or size-related impact in terms of orbital shape variation. Future avenues to explore include the study of other potential explanatory factors such as the different embryological origins of the orbital bones, the passage of vessels and nerves, and ethnic origins. This method can also be applied to the study of pathological orbits.

Respiratory Fluid Mechanics of the Effect of Mouth Breathing on High-Arched Palate: Computational Fluid Dynamics Analyses

Computational fluid dynamics (CFD) was introduced into the study of palate growth and development to explain the mechanisms by which mouth breathing affects palate descent from an aerodynamic perspective. Cone beam computed tomography (CBCT) data were used to reconstruct a 3-dimensional model during natural mouth breathing of a volunteer. The model was imported into CFX 19.0 for numerical simulation of nasal breathing, mouth-nasal breathing, and mouth breathing. The pressure in the oronasal cavity was analyzed, and the pressure difference between the oral and nasal surfaces of hard palate under different breathing patterns was calculated. CFD can be used to simulate the stress on the oral and nasal surfaces of the palate under different breathing patterns. The pressure differences and resultant force between the oral and nasal surfaces of the hard palate during nasal inspiration, nasal expiration, mouth-nasal inspiration, mouth-nasal expiration, mouth inspiration, and mouth expiration were 0 Pa, 4 Pa (upward), 9 Pa (upward), 3 Pa (downward), 474 Pa (upward), 263 Pa (downward), respectively, and 87.99 N (upward), 88.03 N (upward), 88.01 N (upward), 88.01 N (upward), 88.05 N (upward), 87.94 N (upward), respectively. Therefore, CFD can be used to investigate the growth and development of the palate. When the volunteer opened his mouth, the pressure difference between the oral and nasal surfaces of the hard palate was about 88 N upward regardless of whether there was airflow in the mouth. The reversal of the direction of the force on the hard palate may be one of the factors affecting its descent of it.

Pediatric Panfacial Fractures

Pediatric panfacial trauma is a rare occurrence with poorly understood implications for the growing child. Treatment algorithms largely mirror adult panfacial protocols with notable exceptions including augmented healing and remodeling capacities that favor nonoperative management, limited exposure to avoid disruption of osseous suture and synchondroses growth centers, and creative fracture fixation techniques in the setting of an immature craniomaxillofacial skeleton. The following article provides a review of our institutional philosophy in the management of these challenges injuries with important anatomic, epidemiologic, examination, sequencing, and postoperative considerations.

Influences of Adenoid Hypertrophy on Children's Maxillofacial Development

This study aims to investigate the association between adenoid hypertrophy and facial development. A total of 388 children aged 1-13 years old who had undergone head MRI in Foshan Maternal and Child Health Hospital were collected, including 196 hypertrophic cases and 192 normal cases. The maxillofacial soft tissue indicators were measured and compared. The A/N ratio and adenoid thickness consistently increased with age in the hypertrophic group and the A/N ratio reached a maximum value three years earlier than the normal group. The pharyngeal airway space, vallecula of epiglottis to anterior plane distance of the third/fourth cervical vertebrae, angle of convexity, total angle of convexity, and the nasolabial angle in the hypertrophy group were smaller than those in the control group (p < 0.05). The thickness of adenoids, palate height, palate length, and tongue length in the hypertrophy group exceeded that of the control group (p < 0.05). To conclude, adenoid hypertrophy was associated with craniofacial features such as a convex facial profile, a narrowed nasopharyngeal airway, an elongated and heightened palate, a lengthened tongue or a lower tongue position. These findings emphasize the importance of early intervention for children with adenoid hypertrophy to mitigate potential adverse effects on maxillofacial development.

The Physiological Function of Deglutition and Swallowing in Patients With Maxillary Protrusion After Mandibular Advancement

The objective of this study was to determine the tongue-palatal contact changes in patients with skeletal maxillary protrusion after sagittal split ramus osteotomy (SSRO) during swallowing. In this study, 15 patients with maxillary protrusion and 10 normal subjects participated. Before and 3 months after surgery, tongue-palatal contact patterns during swallowing of patients with maxillary protrusion as well as controls were evaluated by electropalatography. The electrode contact number in the alveolar, palatal, and velar parts was examined. The swallowing duration of each phase was also evaluated. In the lateral area of the velar part, incomplete electrode contact was shown at 0.3 seconds in patients with maxillary protrusion. The electrode contact number in the velar part at 0.3 seconds before tongue-palatal complete contact was significantly less in the preoperative patients compared with the controls ( P < 0.05). A small increase in the electrode contact number of the velar part was shown in the postoperative patients at 0.3 and 0.2 seconds before tongue-palatal complete contact ( P < 0.05). The pharyngeal phase duration was significantly larger in the patients with maxillary protrusion before SSRO compared with the controls ( P < 0.05). After SSRO, the pharyngeal phase duration was significantly shortened. It was shown that the tongue-palatal contact pattern during swallowing in patients with maxillary protrusion improved after orthognathic surgery, and the pharyngeal phase duration was also shortened. It is suggested that the changes in the mesiodistal mandibular position by orthognathic surgery can improve tongue posture and movement during swallowing.

Differences in morphology of temporomandibular joint ankylosis of traumatic and infective origin

The aim of this study was to determine whether there are any differences in morphology between temporomandibular joint ankylosis (TMJA) of traumatic and infective origin. Cone beam computed tomography (CBCT) scans of 25 patients (28 joints) with TMJA of traumatic origin (trauma group) and 15 patients (15 joints) with TMJA of infectious origin (infection group) were included. The following morphological parameters were evaluated on multiple sections of the CBCT scans: lateral juxta-articular bone growth, residual condyle, residual glenoid fossa, ramus thickening, ankylotic mass fusion line, sclerosis of the ankylosed condyle and spongiosa of the glenoid fossa, and mastoid and glenoid fossa air cell obliteration. Lateral juxta-articular bone growth, juxta-articular extension of fusion, and the presence of normal medial residual condyle and residual glenoid fossa were exclusively found in post-traumatic TMJA. There were differences in ramus thickening (82.1% in trauma vs 53.3% in infection), sclerosis of the ankylosed condyle (100% in trauma vs 60% in infection), and sclerosis of the spongiosa of the glenoid fossa (100% in trauma vs 46.7% in infection) between the trauma and infection groups. Mastoid and glenoid fossa air cell obliteration was found more frequently in the infection group (mastoid obliteration: 23.1% in infection vs 4% in trauma; glenoid obliteration: 66.7% in infection vs 55.6% in trauma ). CBCT imaging can be helpful in differentiating between TMJA of traumatic and infectious origin.

Correlation of masticatory muscle activity and occlusal function with craniofacial morphology: a prospective cohort study

OBJECTIVES

Masticatory function, including masticatory muscle activity and occlusal function, can be affected by craniofacial morphology. This study aimed to investigate the relationship between craniofacial morphology and masticatory function in participants who had completed orthodontic treatment at least two years before and had stable occlusion.

MATERIALS AND METHODS

Fourty-two healthy participants were prospectively enrolled and divided into three vertical cephalometric groups according to the mandibular plane angle. Masticatory muscle activity (MMA) in the masseter and anterior temporalis muscles was assessed using surface electromyography. The occlusal contact area (OCA) and occlusal force (OF), defined as occlusal function in this study, were evaluated using occlusal pressure mapping system. Masticatory muscle efficiency (MME) was calculated by dividing MMA by OF. The craniofacial morphology was analyzed using a lateral cephalogram. The masticatory function was compared using one-way analysis of variance. Pearson correlations were used to assess relationships between craniofacial morphology and masticatory function.

RESULTS

The hypodivergent group had the lowest MMAand the highest MME in the masseter (167.32 ± 74.92 µV and 0.14 ± 0.06 µV/N, respectively) and anterior temporalis muscles (0.18 ± 0.08 µV/N, p < 0.05). MMA in the masseter showed a positive relationship with mandibular plane angle (r = 0.358), whereas OCA (r = -0.422) and OF (r = -0.383) demonstrated a negative relationship (p < 0.05). The anterior temporalis muscle activity negatively correlated with ramus height (r = -0.364, p < 0.05).

CONCLUSIONS

Vertical craniofacial morphology was related to masticatory function. Hypodivergent individuals may have low MMA and high occlusal function, resulting in good masticatory muscle efficiency.

CLINICAL RELEVANCE

Hypodivergent individuals require careful consideration in orthodontic diagnosis and prosthetic treatment planning.

Comparison of Changes in Intraoral Dynamic Space (Donders Space) with Myofunctional Therapy in Skeletal Class II Division 1 Malocclusion: An In Vivo Study

AIM

To evaluate the changes in the intraoral dynamic space with myofunctional therapy in skeletal class II division 1 malocclusion using three-dimensional digital volume tomography (3D-DVT).

MATERIALS AND METHODS

The study type is observational and the duration of intervention was 3 years. Dental casts obtained from 20 samples of 11-14 years age-group were collected and 3D-DVT scans were performed prior to and after the myofunctional therapy. The parameters depicting the arch perimeter, arch width, arch length, arch shape, and arch volume on dental cast were used in the study using several linear and volumetric measurements. All parameters were compared before and after myofunctional therapy using t-test.

RESULTS

The Intraoral volume before myofunctional therapy (T0) was 5.59 mL and after myofunctional therapy (T1), it was 7.22 mL. Significant changes were seen in intraoral volume, arch perimeter, arch length, and intercanine and intermolar arch width and the arch shape. Linear and volumetric measurements were increased after myofunctional therapy.

CONCLUSION

Myofunctional appliances lead to an expansion in the anteroposterior and sagittal direction thus increasing the Donders space and leading to proper formation of dental arches and proper positioning of the teeth.

CLINICAL SIGNIFICANCE

Myofunctional therapy is an effective method of increasing arch width, length, and volume. This therapy can be used in routine practices in young children with constricted arch and improvement in facial esthetic.

Combined Dynamic Osteotomies for Craniosynostosis

Background

In primary craniosynostosis, the premature fusion of one or more sutures prevents the perpendicular expansion of brain tissue (primary defect). Providing space for the brain to expand, the compensatory growth of unaffected sutures causes progressive skull deformation (secondary defect). Understanding the need to treat the osteogenic matrix responsible for the cranial vault's shape was essential to develop a novel surgical concept known as dynamic osteotomy. It uses springs to activate stenotic sutures and trigger dura-mater distension while flexibilizing compensatory osseous defects via helicoid osteotomy (nautilus technique), allowing for efficient bone expansion and remodeling in craniosynostosis.

Method

This case series describes patients with craniosynostosis treated with dynamic osteotomy utilizing structural transformation inductors such as springs and helicoid osteotomy (nautilus technique), operated on between July 2004 and January 2020 at a single center in Brazil.

Result

Dynamic osteotomy longitudinally achieved stable osseous remodeling during growth period while maintaining good vitality and continuity of the osteotomized cranial vault.

Conclusion

Dynamic osteotomy utilizing springs and nautilus technique, alone or in combination, is a successful treatment of craniosynostosis regardless of patient's age.

Relation between Maximum Oral Muscle Pressure and Dentoalveolar Characteristics in Patients with Cleft Lip and/or Palate: A Prospective Comparative Study

BACKGROUND

Perioral muscle function, which influences maxillofacial growth and tooth position, can be affected in patients with oral clefts due to their inherent anatomical characteristics and the multiple surgical corrections performed. This research aims to (1) compare the maximum oral muscle pressure of subjects with and without isolated cleft palate (CP) or unilateral cleft lip and palate (UCLP), (2) investigate its influence on their dentoalveolar characteristics, and (3) investigate the influence of functional habits on the maximum oral muscle pressure in patients with and without cleft.

MATERIAL AND METHODS

Subjects with and without CP and UCLP seeking treatment at the Department of Orthodontics of University Hospitals Leuven between January 2021 and August 2022 were invited to participate. The Iowa Oral Performance Instrument (IOPI) was used to measure their maximum tongue, lip, and cheek pressure. An imbalance score was calculated to express the relationship between tongue and lip pressure. Upper and lower intercanine (ICD) and intermolar distance (IMD) were measured on 3D digital dental casts, and the presence of functional habits was reported by the patients. The data were analyzed with multivariable linear models, correcting for age and gender.

RESULTS

44 subjects with CP or UCLP (mean age: 12.00 years) and 104 non-affected patients (mean age: 11.13 years) were included. No significant differences in maximum oral muscle pressure or imbalance score were detected between controls and clefts or between cleft types. Significantly smaller upper ICDs and larger upper and lower IMDs were found in patients with clefts. A significant difference between controls and clefts was found in the relationship between oral muscle pressure and transversal jaw width. In cleft patients, the higher the maximum tongue pressure, the wider the upper and lower IMD, the higher the lip pressure, the smaller the upper and lower ICD and IMD, and the higher the imbalance score, the larger the upper and lower IMD and lower ICD. An imbalance favoring the tongue was found in cleft patients. The influence of functional habits on the maximum oral muscle pressure was not statistically different between clefts and controls.

CONCLUSION

Patients with CP or UCLP did not present reduced maximum oral muscle pressure compared with patients without a cleft. In cleft patients, tongue pressure was consistently greater than lip pressure, and those who presented a larger maxillary width presented systematically higher imbalance scores (favoring the tongue) than those with narrow maxillae. Therefore, the influence of slow maxillary expansion on maximum oral muscle pressure in cleft patients should not be underestimated.

Mouth breathing induces condylar remodelling and chondrocyte apoptosis via both the extrinsic and mitochondrial pathways in male adolescent rats

The prevalence of mouth breathing is high in children and adolescents. It causes various changes to the respiratory tract and, consequently, craniofacial growth deformities. However, the underlying mechanisms contributing to these effects are obscure. Herein, we aimed to study the effects of mouth breathing on chondrocyte proliferation and death in the condylar cartilage and morphological changes in the mandible and condyle. Additionally, we aimed to elucidate the mechanisms underlying chondrocyte apoptosis and investigate any variations in the related pathways. Subchondral bone resorption and decreased condylar cartilage thickness were observed in mouth-breathing rats; further, mRNA expression levels of Collagen II, Aggrecan, and Sox 9 were lower in the mouth breathing group, while those of matrix metalloproteinase 9 increased. TdT-mediated dUTP nick end labelling staining and immunohistochemistry analyses showed that apoptosis occurred in the proliferative and hypertrophic layers of cartilage in the mouth breathing group. TNF, BAX, cytochrome c, and cleaved-caspase-3 were highly expressed in the condylar cartilage of the mouth-breathing rats. These results suggest that mouth breathing leads to subchondral bone resorption, cartilage layer thinning, and cartilage matrix destruction, inducing chondrocyte apoptosis via both the extrinsic and mitochondrial apoptosis pathways.

Cranial structure and condylar asymmetry of adult patients with rheumatoid arthritis

OBJECTIVE

The aim of this prospective cross sectional study was to evaluate the cranial structure and condylar asymmetry of adult patients with rheumatoid arthritis (RA) diagnosed after 25 years of age compared to a healthy adult control group.

METHODS

Eighteen adult patients (57.4 ± 11.4 years) with RA were compared with a control group. Cephalometric analysis and the Habets method for the calculation of the condylar asymmetry were used. The main cephalometric data investigated were focused on the diagnosis of hyperdivergent cranial structure (NSL/ML, NL/ML), backwards rotation of the mandible (Fh/ML), short vertical ramus (Ar:Go), steep mandibular plane (ML/Oc).

RESULTS

The cephalometric data considered were not significantly different in the RA vs controls except for the steepness of the occlusal plane (NL/Oc), which was steeper in the patients group (P < 0.02) and the ramus of the mandible which was greater in patients. The asymmetry of the condyles was significant (P < 0.003) and different from the control group, but that of the ramus was not.

CONCLUSIONS

In this study, RA patients diagnosed after 25 years of age did not show a different pattern of growth with respect to the control group. As expected, the condyles showed a difference being asymmetrical in RA patients due to the high turnover of this joint reacting to severe systemic inflammation in conditions of continuous functional work, load and forces. This study follows a previous study with the same research plan conducted on young JIA patients who showed a different pattern of growth of the skull leading to a severe hyperdivergent cranial structure with backward rotation of the mandible; this is mainly due to the insufficient growth of the condylar site exposed to the inflammatory process during development. Unlike JIA patients, this study showed that RA patients follow an individual growth pattern not affected by inflammation, even if they show joint asymmetry.

Age-related hypertrophy of adenoid and tonsil with its relationship with craniofacial morphology

BACKGROUND

When analyzing the relationship between adenotonsillar hypertrophy and craniofacial morphology, researchers generally regarded hypertrophied adenoids and tonsils as a whole. It remains unclear whether different enlarged sites of pharyngeal lymphoid tissue would correlate with multiple craniofacial subtypes. We hypothesized there would be craniofacial subtypes correlated with different locations of hypertrophied adenoid and tonsil.

METHODS

Lateral cephalometric radiographs were obtained from 466 children (171 boys and 295 girls, aged 12.27 ± 2.69 years). They were divided into four groups according to different sites of enlarged pharyngeal lymphoid tissue: adenoid hypertrophy group (AG, n = 126), tonsillar hypertrophy group (TG, n = 59), adenotonsillar hypertrophy group (ATG, n = 69) and control group (CG, n = 212). Five commonly used angles for cephalometric measurements were investigated: SNA (Sella-Nasion-Point A), SNB (Sella-Nasion-Point B), ANB (Point A-Nasion-Point B), mandibular plane angle (MP/SN) and Y-axis angle (SGn/FH).

RESULTS

Children with isolated tonsillar hypertrophy correlated with increased SNA (unstandardized regression coefficient B = 1.38, p = 0.009) and SNB (B = 1.99, p = 0.001) compared with controls. However, children with isolated adenoid hypertrophy correlated with decreased SNB (B=-0.94, p = 0.036), increased ANB (B = 0.74, p = 0.014) and increased MP/SN (B = 2.22, p < 0.001). Similarly, children with adenotonsillar hypertrophy correlated with decreased SNB (B=-1.36, p = 0.015), increased ANB (B = 1.35, p < 0.001) and increased MP/SN (B = 2.64, p = 0.001).

CONCLUSIONS

Isolated adenoid hypertrophy correlated with a retrognathic mandible, an increased maxillo-mandibular sagittal discrepancy, and an increased mandibular plane angle. Isolated tonsillar hypertrophy correlated with maxillary and mandibular protrusion. Adenotonsillar hypertrophy did not show a superimposed craniofacial pattern of the above two but showed the same craniofacial pattern as isolated adenoid hypertrophy.

Are morphological and morphometric characteristics of maxillary anterior region and nasopalatine canal related to each other?

OBJECTIVES

The main purpose of this article was to clarify the relationship of anterior bone and tooth morphology with NPC. The anatomical features of the NPC region in three dimensions from coronal, axial, and sagittal directions were analyzed using CBCT and the effects of age, gender, sagittal root positions (SRPs) of central teeth, anterior overbite depth (AOD), central incisor (CI)/palatal plane (PP) angle, NPC/PP angle, and collum angles (CA) on NPC were evaluated in a group of the Turkish population.

MATERIALS AND METHODS

In this retrospective study, CBCTs of a total of 330 individuals between the ages of 17 and 82 were evaluated. The effects of SRP, AOD, CI/PP angle, NPC/PP angle and CA on the anatomical features of NPC were examined on the basis of age and gender. Descriptive statistics, Kolmogorov-Smirnov, Chi-square, Wilcoxon, Mann-Whitney-U, Kruskal-Wallis, and Spearman correlation tests were used. p values of < 0.05 were accepted as statistically significant.

RESULTS

While the SRPs, CI/PP angle, NPC/PP angle, CA, and age did not differ statistically according to NPC shape (p > 0.05), NPC shape varied according to gender and AOD (p < 0.05). It was found that cylindrical NPC (32.8%) was more common in females, while conical-shaped NPC (30.7%) was more common in males (p < 0.01). While most conical NPC was detected in individuals with Class I overbite depth, cylindrical NPCs were found in Class II and III individuals (p < 0.01).

CONCLUSIONS

The results showed that gender and AOD are influential factors on NPC shape. While conical-shaped NPC is more common in individuals with bite depth incisal, cylindrical-shaped NPC is more likely to be seen in individuals with middle and cervical thirds.

Influence of age and diet consistency on the oral muscle pressure of orthodontically treated and untreated subjects with normal occlusion and comparison of their 3D facial shape

OBJECTIVES

(1) To investigate the effect of age and diet consistency on maximum lips, tongue and cheek pressure of orthodontically treated and untreated subjects with normal, Class I dental occlusion, (2) to find out whether there is a muscle imbalance between anterior tongue and lip pressure in the same subjects at different ages and (3) to compare the 3D facial shape of treated and untreated individuals.

MATERIAL AND METHODS

Subjects with normal occlusion were prospectively grouped into orthodontically treated/untreated and in children/adolescents/adults. Iowa Oral Performance Instrument was used to record the maximum muscle pressure. Two-way ANOVA and Tukey post hoc test analysed age-specific differences in muscle pressure. Two-way ANCOVA analysed the effect of diet consistency on muscle pressure. Lips and tongue imbalance was analysed using z-scores and 3D faces using a generalized Procrustes analysis.

RESULTS

One hundred thirty-five orthodontically untreated and 114 treated participants were included. Muscle pressure was found to increase with age in both groups, except for the tongue in treated subjects. No differences in the balance between lips and tongue muscle pressure were found, but a higher cheek pressure in untreated adults (p<0.05) was observed. 3D facial shapes showed subtle differences. Untreated subjects with soft diet consistency showed lower lip pressure (p<0.05).

CONCLUSION

Oral muscle pressure of orthodontically treated patients without relapse does not differ from that of untreated patients with Class-I occlusion.

CLINICAL RELEVANCE

This study provides normative lip, tongue and cheek muscle pressure in subjects with normal occlusion, which can be used for diagnosis, treatment planning and stability.

Malocclusions and oral dysfunctions: A comprehensive epidemiological study on 359 schoolchildren in France

OBJECTIVES

The purpose was to conduct a comprehensive study of malocclusions and oral dysfunctions on 11-year-old children and to study the risk factors associated with malocclusions.

MATERIAL AND METHODS

A cross-sectional descriptive epidemiological survey was conducted among 359 children in France. A clinical examination was conducted, and orthodontic and oral functional data were collected. In addition, the need for orthodontic treatment was evaluated using the criteria defined by of the French National Authority for Health (HAS). Finally, a univariate and multivariate analysis was performed to assess the risks associated with malocclusions.

RESULTS

Most children (88%) exhibited a malocclusion, regardless of gender (p = .912). The examination of oral functions identified a large number of swallowing (87%) and respiration (42.7%) disorders. The presence of malocclusion was statistically linked to the low position of the tongue at rest (p < .001), abnormal swallowing (p = .03), and improper mouth breathing (p = .001). After a multivariate analysis, the type of respiration (odds ratio [OR] = 3.2 [1.4-7.3]) and the position of tongue at rest (OR = 3.43 [1.7-7.1]) were the two most prominent factors in the prediction of emerging malocclusion.

CONCLUSION

This epidemiological survey reveals a high prevalence of dental malocclusions and functional disorders. Oral respiration and the low position of the tongue at rest are the most important factors in the prediction of a malocclusion.

Pediatric sleep-disordered breathing in Shanghai: characteristics, independent risk factors and its association with malocclusion

OBJECTIVES

This study aimed to determine the prevalence and independent risk factors of SDB, and explore its association with malocclusion among 6-11-year-old children in Shanghai, China.

METHODS

A cluster sampling procedure was adopted in this cross-sectional study. Pediatric Sleep Questionnaire (PSQ) was applied to evaluate the presence of SDB. Questionnaires including PSQ, medical history, family history, and daily habits/environment were completed by parents under instruction, and oral examinations were implemented by well-trained orthodontists. Multivariable logistic regression was applied to identify independent risk factors for SDB. Chi-square tests and Spearman's Rank Correlation were used to estimate the relationship between SDB and malocclusion.

RESULTS

A total of 3433 subjects (1788 males and 1645 females) were included in the study. The SDB prevalence was about 17.7%. Allergic rhinitis (OR 1.39, 95% CI 1.09-1.79), adenotonsillar hypertrophy (OR 2.39, 95% CI 1.82-3.19), paternal snoring (OR 1.97, 95% CI 1.53-2.53), and maternal snoring (OR 1.35, 95% CI 1.05-1.73) were independent risk factors for SDB. The SDB prevalence was higher in children with retrusive mandibles than in proper or excessive ones. No significant difference was observed in the correlation between SDB and lateral facial profile, mandible plane angle, constricted dental arch form, the severity of anterior overjet and overbite, degree of crowding and spacing, and the presence of crossbite and open bite.

CONCLUSIONS

The prevalence of SDB in primary students in the Chinese urban population was high and highly associated with mandible retrusion. The independent risk factors included Allergic rhinitis, adenotonsillar hypertrophy, paternal snoring, and maternal snoring. More efforts should be made to enhance public education about SDB and related dental-maxillofacial abnormalities.

Mandibular condyle changes in rats with unilateral masticatory function

OBJECTIVE

Certain malocclusions or unilateral tooth loss can lead to asymmetric functional load of the two mandibular sides during mastication and induce skeletal asymmetries to the condylar process of growing individuals. However, in adults, asymmetric function may have a different impact. The aim of the present study was to investigate three-dimensionally the effects of unilateral masticatory function on the condylar process morphology in growing and adult rats and the adaptive processes to differential condylar loading.

MATERIALS AND METHODS

Fifty-six growing and adult Wistar rats aged 4 and 26 weeks respectively were obtained. The maxillary right molars of the experimental animals were extracted and all animals were followed for 12 weeks. Three-dimensional images were obtained by an in-vivo microcomputed tomography (micro-CT) examination. The following measurements were studied: condylar process height, condylar base width, and condylar cross-sectional surface.

RESULTS

While no differences were found with regards to condylar process height and base width, the cross-section of the condyle on the extraction side did not increase during growth in the young rats. No such differences were found in adults. Young rats had statistically significantly shorter condylar height, base width and cross-sectional surface than the adult rats and showed significant growth of these structures during the experimental period.

CONCLUSION

Condylar height and base width growth are not hindered by reduced occlusal function, contrary to the average cross-sectional surface, which implies that the condyle form of growing individuals becomes thinner while maintaining its length, in the absence of occlusal stimuli. The condyle of adult rats with extractions is less affected by occlusion changes.

Skeletal and dentoalveolar characteristics of maxillary lateral incisor agenesis patients: a comparative cross-sectional study

BACKGROUND

The aim of the study was to evaluate the cephalometric and dentoalveolar characteristics of maxillary lateral incisor agenesis patients, and to compare the findings to a matched control group without tooth agenesis, excluding third molars, from the same population.

METHODS

The pre-orthodontic records of 72 non-growing patients, who were treated at the Orthodontic Department, Faculty of Dentistry, Alexandria University, were used to address the aim of this retrospective study. Patients having unilateral or bilateral maxillary lateral incisor agenesis, with no history of previous orthodontic treatment, congenital craniofacial malformations, facial trauma, or surgeries were divided into two test groups based on the pattern of maxillary lateral incisors agenesis (group I: unilateral (UMLIA), group II: bilateral (BMLIA)). A control group (group III (CTRL)) having a complete set of permanent dentition (excluding third molars), and having no dental anomalies was age-matched with the test groups. Measurements were performed on the pre-orthodontic lateral cephalometric radiographs and the pre-orthodontic digital dental casts. The measured variables were compared between the groups using one-way ANOVA and Kruskal Wallis tests according to the normality of the variable. In case of significant results, both tests were followed by multiple pairwise comparisons using Bonferroni adjusted significance level. Significance level was set at P < 0.05.

RESULTS

BMLIA group showed a smaller SNA angle and maxillary length, a more negative ANB angle and Wits appraisal, and a larger Maxillo-mandibular differential than UMLIA and/or CTRL group. The dental and soft tissue cephalometric measurements did not show any significant differences between the groups. Dentoalveolar cast measurements showed that BMLIA patients presented with significantly smaller maxillary inter-canine width than UMLIA and CTRL patients.

CONCLUSIONS

Cephalometric analysis has shown that subjects with BMLIA have a statistically significant reduced ANB and maxillary length. Tooth eruption may play a role in the development of the maxillary arch.

Management of the secondary growth defect

Temporomandibular reconstruction has clear aims including the restoration of mandibular form and function, to decrease patient disability and to prevent disease progression. In addition paediatric patients have growth and re-modelling considerations and the need to minimise any secondary growth defect. The involvement of a multidisciplinary team is deemed essential for both the child and parents. In some patients crisis intervention may be required and early reconstruction might be necessary dependant on the severity of impairment. The aetiology of end stage TMJ disease, unilateral/bilateral disease and the degree of patient compromise will guide timing and choice of treatment. Reducing repeated surgery and facilitating patient compliance may potentiate mandibular growth.