Prediction of mandibular growth rotation

3D superimposition of craniofacial imaging-The utility of multicentre collaborations

Clinical applications of 3D image registration and superimposition have contributed to better understanding growth changes and clinical outcomes. The use of 3D dental and craniofacial imaging in dentistry requires validate image analysis methods for improved diagnosis, treatment planning, navigation and assessment of treatment response. Volumetric 3D images, such as cone-beam computed tomography, can now be superimposed by voxels, surfaces or landmarks. Regardless of the image modality or the software tools, the concepts of regions or points of reference affect all quantitative of qualitative assessments. This study reviews current state of the art in 3D image analysis including 3D superimpositions relative to the cranial base and different regional superimpositions, the development of open source and commercial tools for 3D analysis, how this technology has increased clinical research collaborations from centres all around the globe, some insight on how to incorporate artificial intelligence for big data analysis and progress towards personalized orthodontics.

Association between Gingival Biotype and Facial Typology through Cephalometric Evaluation and Three-Dimensional Facial Scanning

In dentistry, the assessment of periodontal biotype is considered one of the most important parameters with which to plan treatment, and craniofacial morphology might affect it. The aim of this study was to investigate the association between facial typology and gingival biotype in patients by means of two-dimensional and three-dimensional evaluations of facial typology. This study included 121 participants searching for orthodontic treatment (43 M, 78 F; 20.4 ± 10.4). Gingival biotype was evaluated based on the transparency of the periodontal probe through the gingival margin of the mid-buccal sulcus for both upper (UGB) and lower (LGB) anterior teeth. SellionNasion^GonionGnation (SN^GoGn) and CondylionGonionMenton (CoGoMe^) angles were measured on two-dimensional cephalograms. Three-dimensional face scans were acquired by means of a three-dimensional facial scanner (3dMD system) and successively analyzed to assess the facial typology using the ratio between lower facial height (SNMe) and total facial height (NMe). A chi-squared test and regression analysis were used to evaluate the associations between gingival biotype and facial morphology (p < 0.05). The chi-squared test showed that there was no statistically significant association between facial typology and gingival biotype (UGB p = 0.83; LGB p = 0.75). The logistic regression showed an association between SNMe/NMe and the UGB (p = 0.036), and SNMe/NMe and LGB (p = 0.049). The decreased ratio of SNMe/NMe might be a protective factor for a thin gingival biotype.

A longitudinal comparison of body height growth of orthodontically treated Class I and Class III adolescents compared with the general population

INTRODUCTION

The aim of this study was to evaluate the height growth of Class I and III orthodontic patients according to the Fishman skeletal maturation index (SMI) and to compare it with that of a general population.

METHODS

The study sample included 81 Class I and 71 Class III adolescents who had height measurements and hand-wrist radiographs taken annually and categorized according to SMI. Height completion rate, residual height, height increase per sequential SMI stage, and height velocity were analyzed. Sex differences were evaluated and comparisons between Class I and Class III groups were made. In addition, the height of orthodontic patients was indirectly compared with that of the general population.

RESULTS

In boys and girls, height completion rate was >90% at SMI 6, residual height was fewer than 10 cm at SMI 7, and height increase per sequential SMI stage was greatest from SMI 6 to SMI 7. Height velocity was greatest from SMI 5 to SMI 6 in boys and from SMI 4 to SMI 5 in girls.

CONCLUSIONS

There was no significant difference in body height parameters for all SMI stages between Class I and Class III adolescents. Adolescents who had orthodontic treatment were not shorter in stature at growth completion compared with the general population.

Application of the foramina of the trigeminal nerve as landmarks for analysis of craniofacial morphology

Objective

The objective of this study was to develop new parameters based on the foramina of the trigeminal nerve and to compare them with the conventional cephalometric parameters in different facial skeletal types.

Methods

Cone-beam computed tomography (CBCT) scans and cephalograms from 147 adult patients (57 males and 90 females; mean age, 26.1 years) were categorized as Class I (1° < ANB < 3°), Class II (ANB > 5°), and Class III (ANB < −1°). Seven foramina in the craniofacial area—foramen rotundum (Rot), foramen ovale (Ov), infraorbital foramen, greater palatine foramen, incisive foramen (IF), mandibular foramen (MDF), and mental foramen (MTF)—were identified in the CBCT images. Various linear, angular, and ratio parameters were compared between the groups by using the foramina, and the relationship between the new parameters and the conventional cephalometric parameters was assessed.

Results

The distances between the foramina in the cranial base did not differ among the three groups. However, the Rot-IF length was shorter in female Class III patients, while the Ov-MTF length, MDF-MTF length, and Ov-MDF length were shorter in Class II patients than in Class III patients of both sexes. The MDF-MTF/FH plane angle was larger in Class II patients than in Class III patients of both sexes. Most parameters showed moderate to high correlations, but the Ov-MDF-MTF angle showed a relatively low correlation with the gonial angle.

Conclusions

The foramina of the trigeminal nerve can be used to supplement assessments based on the conventional skeletal landmarks on CBCT images.

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.

Dentoskeletal morphology in adults with Class I, Class II Division 1, or Class II Division 2 malocclusion with increased overbite

INTRODUCTION

The treatment options for adults with increased overbite are limited to dentoalveolar changes that camouflage the condition. Because of high relapse tendency, defining the problem area is important when creating a treatment plan. This study aimed to evaluate dentoskeletal morphology in skeletal Class I and II anomalies associated with Angle Class I, Class II Division 1 (Class II/1), and Class II Division 2 (Class II/2) malocclusions with increased overbite compared with normal occlusion.

METHODS

Pretreatment cephalograms of 306 patients (131 men, 175 women; overall ages 18-45 years) were evaluated. Four groups were constructed. Three groups had increased overbite (>4.5 mm): group 1 (n = 96) skeletal Class I (ANB = 0.5°-4°), group 2 (n = 85) skeletal Class II (ANB >4.5°) with Class II/1; and group 3 (n = 79) skeletal Class II with Class II/2 malocclusion. Group 4 as a control (n = 46) skeletal Class I normal overbite. Dental and skeletal characteristics of the groups were compared by sex. For statistical evaluations, analysis of variance followed by Tukey post hoc, Mann-Whitney U, and Kruskall-Wallis tests were used. Additionally correlation coefficients between overbite and skeletal/dental parameters were calculated.

RESULTS

Between sexes, with regard to skeletal parameters, the men had greater values in millimetric measurements, and the women had higher SN/GoGn values. Maxillary/mandibular molar heights and the mandibular incisor heights were higher in men. In group 1, decreased lower anterior facial height (LAFH), retrusive mandibular incisors, and increased interincisal degree were determined. The maxillary molars were intrusive, whereas the vertical position of the mandibular molars and incisors in both jaws were normal. In group 2, retrognathic mandible, increased LAFH and mandibular plane angle, extrusive maxillary/mandibular incisors, protrusive mandibular incisors, and decreased interincisal degree were found. In group 3, decreased LAFH, increased interincisal degree, and retrusive incisors in both jaws were determined. There were significant negative correlations between SN/GoGN, palatal plane, and overbite in group 2 and between ANS-SN and overbite in group 3, and positive correlation between interinsical angle and overbite in all increased overbite groups.

CONCLUSIONS

Dental morphology seems to be the main factor of increased overbite. Differences between groups were related primarily to inclinations and vertical positions of the incisors, rather than molar positions.

Does overbite reduction affect smile esthetics?

OBJECTIVES

To compare the effects of two common methods of overbite reduction on smile esthetics.

MATERIALS AND METHODS

A prospective clinical trial was conducted with 32 patients in whom overbite reduction was achieved using a maxillary incisor intrusion arch (18 patients) or flat anterior bite plate (14 patients). Clinical and cephalometric records were compared pretreatment (T1), after overbite reduction (T2), and posttreatment (T3).

RESULTS

Both treatment groups experienced a reduction in overbite and maxillary and mandibular incisor proclination during treatment (T1-T3). The center of resistance of the maxillary incisor and the incisal edge was significantly intruded in the intrusion arch group during overbite reduction (T1-T2). However, most of the intrusion of the center of resistance was lost by the end of treatment (T2-T3). Both treatment groups experienced a reduction in maxillary incisor display and flattening of the smile arc during overbite reduction.

CONCLUSIONS

Both overbite reduction methods caused a decrease in incisor display and flattening of the smile arc. Smiles were improved in some patients by the end of treatment. However, reduction in incisor display persisted. Clinicians should take precautions to prevent negative effects of overbite reduction.

Direct Anterior Tracks: Early and Functional Management of Class III Malocclusions-Case Report and Literature Review

The prevalence of class III malocclusion ranged from 0 to 26% in different populations. Many types of treatments have been described in dental literature. The results of early treatment have been positive. The purpose of this report is to describe the case of a four-year-old patient with class III malocclusion who received an innovative treatment using direct anterior tracks. This therapy efficiently obtained immediate improvement of profile and occlusal relationships.

Whole-exome sequencing in a Japanese pedigree implicates a rare non-synonymous single-nucleotide variant in BEST3 as a candidate for mandibular prognathism

Mandibular prognathism is a phenotype of facial deformity seen in populations around the world, but with higher incidence among East Asian populations. Five genome-wide nonparametric linkage analyses and a genome-wide association study to identify susceptibility loci of the phenotype have shown inconsistent results. To explore variants related to mandibular prognathism, we undertook whole-exome sequencing in a Japanese pedigree. The pedigree was ascertained as mandibular prognathism. The pedigree comprised 15 individuals from 4 generations. Four affected individuals across 2 generations and 5 unaffected individuals were chosen for whole-exome sequencing. Five non-synonymous single-nucleotide variants (SNVs) of UBASH3B, OR6M1, OR8D4, OR8B4, and BEST3 genes were detected in all 4 affected individuals, but in none of the 5 unaffected individuals. A non-synonymous SNV of the BEST3 gene, Chr12(GRCh37):g.70048878G>T, NM_032735.2:c.1816C>A, p.(L606I), was identified as rare missense variant. BEST3 is located on chromosome 12q15 and encodes bestrophin 3 from the bestrophin family of anion channels. The 4 other non-synonymous SNVs of UBASH3B, OR6M1, OR8D4, and OR8B4 were not considered plausible candidates for mandibular prognathism. Our whole-exome sequencing implicates a rare non-synonymous SNV of BEST3 as a candidate for mandibular prognathism in the Japanese pedigree.

Predicting adult facial type from mandibular landmark data at young ages

OBJECTIVES

To assess the potential of predicting adult facial types at different stages of mandibular development.

SETTING AND SAMPLE POPULATION

A total of 941 participants from the Bolton-Brush, Denver, Fels, Iowa, Michigan and Oregon growth studies with longitudinal lateral cephalograms (total of 7166) between ages 6-21 years.

MATERIAL AND METHODS

Each participant was placed into one of three facial types based on mandibular plane angle (MPA) from cephalograms taken closest to 18 years of age (range of 15-21 years): hypo-divergent (MPA < 28°), normo-divergent (28°≤ MPA ≤ 39°) and hyper-divergent (MPA > 39°). Cephalograms were categorized into 13 age groups 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17 and 18-21. Twenty-three two-dimensional anatomical landmarks were digitized on the mandible and superimposed using generalized Procrustes analysis, which projects landmarks into a common shape space. Data were analysed within age categories using stepwise discriminant analysis to identify landmarks that distinguish adult facial types and by jackknife cross-validation to test how well young individuals can be reclassified into their adult facial types.

RESULTS

Although each category has multiple best discriminating landmarks among adult types, three landmarks were common across nearly all age categories: menton, gonion and articulare. Individuals were correctly classified better than chance, even among the youngest age category. Cross-validation rates improved with age, and hyper- and hypo-divergent groups have better reclassification rates than the normo-divergent group.

CONCLUSIONS

The discovery of important indicators of adult facial type in the developing mandible helps improve our capacity to predict adult facial types at a younger age.

Do orthopedic corrections of growing retrognathic hyperdivergent patients produce stable results?

OBJECTIVES

To determine if posterior dental intrusion produces stable orthodontic and orthopedic corrections in growing retrognathic hyperdivergent patients.

MATERIALS AND METHODS

The sample included 14 subjects (five males and nine females), who were 13.4 ± 0.7 years pretreatment, treated for 3.5 years, and followed for 3.6 years posttreatment. During the initial orthopedic phase, 150 g NiTi coil springs were attached to two palatal miniscrew implants (MSIs) for maxillary intrusion; two buccal mandibular MSIs were used for posterior vertical control. Full orthodontic therapy was initiated to correct the malocclusions during the orthodontic phase. Patients were recalled a minimum of 1 year posttreatment (mean 3.6 ±1.6 years). Patients were compared to matched untreated controls.

RESULTS

Relative to the untreated controls, during treatment and retention, maxillary and mandibular molars underwent 2.8 mm and 3.7 mm of relative posterior intrusion, respectively. Maxillary incisors were extruded 1.3 mm and the mandibular incisors underwent 2.9 mm of relative intrusion. Overall orthopedic changes included a reduction in the mandibular plane angle (MPA; 3.3°), an increase in SN-Pg (2.4°), an increase in S-N-B (2.1°), and a 4.3 mm relative reduction in anterior facial height. The maxillary incisors, which showed 0.6 mm of intrusion (relative to controls), was the only dental or skeletal measure to show a statistically significant between-group posttreatment difference.

CONCLUSIONS

Except for maxillary incisor position, the substantial dental intrusion and associated orthopedic corrections that were produced during treatment remained stable post-treatment.

Association analysis between rs6184 and rs6180 polymorphisms of growth hormone receptor gene regarding skeletal-facial profile in a Colombian population

Background/Objective

There is strong evidence that genetic factors may affect the craniofacial morphology. This study aimed to examine the association between the rs6184 and rs6180 polymorphic variants of the growth hormone receptor (GHR) gene and skeletal-facial profile in a Colombian population.

Subjects/Methods

Saliva samples from 306 individuals ranging in age from 15 to 53 (mean 24.33) years were collected. Cephalometric parameters were used to categorize the participants as Class I, Class II, or Class III skeletal-facial profile. The polymerase chain reaction-restriction fragment length polymorphism method was used to identify genotypes of the rs6184 and rs6180 single nucleotide polymorphisms (SNPs). The association of polymorphisms with the skeletal-facial profile was assessed separately and adjusted for confounding using a multivariate binary logistic regression model, alongside with analysis of linkage disequilibrium and haplotype associations.

Results

Although individuals carrying the CA genotype of the rs6184 SNP showed both significantly decreased values for ANB angle and increased measures concerning mandibular body length and mandibular length, no significant differences amongst genotype groups of rs6180 SNP were observed. Moreover, chi-square test and logistic regression analysis revealed that the CA genotype of rs6184 SNP and the A-A haplotype were highly associated with Class III skeletal-facial profile.

Conclusions

Although these results do not support that rs6180 SNP could be identified as a predictor for skeletal-facial profile, they suggest that the allele A of rs6184 SNP alone or in combination with other SNPs in the GHR gene yields significant horizontal and longitudinal variations of the mandibular morphology and might be a strong/independent prognostic indicator for Class III skeletal-facial profile in the present population.

Prosthetic Rehabilitation of Edentulous Patients With Implants Based on Facial Profile Assessment: A Case Report

PURPOSE

To introduce a user-friendly protocol for implant-retained prosthetic rehabilitation of fully edentulous patients based on facial profile and the cephalometric intermaxillary relationship.

MATERIALS AND METHODS

The prosthetic rehabilitation of edentulous patients with implants based on facial profile assessment protocol commences with a clinical and cephalometric analysis, followed by a preliminary projection to obtain a harmonious interarch relationship, eventually stabilized by the preplanned prosthesis. The protocol is divided into the following 5 phases: esthetic evaluation; cephalometric-occlusal assessment; surgery; provisionalization; and definitive prosthesis. Evaluation of patient's satisfaction from the treatment provided was performed through a preoperative and postoperative visual analogue scale scores.

RESULTS

The patient was granted immediate function and superior esthetics at day 1 of the treatment. These results were re-evaluated on an interval of 18 months and continued to be stable. The overall treatment time was significantly reduced.

CONCLUSION

Our recommended protocol gives the clinician a chance to grasp results beyond the offered by traditional protocols by using a wider perspective of rehabilitation, involving the patient's facial profile, thus fulfilling the integration of both occlusal and cephalometric parameters in a unified surgical-prosthetic approach.

Correlation between vertical components and skeletal Class II malocclusion in ethnic Javanese

Introduction

The dentoskeletal morphology of Class II malocclusion has been analyzed in several cephalometric investigations. It is crucially important to understand the vertical components in orthodontic treatment. Defining the facial type of an individual is an essential key to obtain an accurate orthodontic diagnosis.

Aim

The aim of this study was to understand the correlation of vertical components in Class II skeletal malocclusion.

Materials and methods

This is a observational descriptive study. This study used lateral cephalograms of Class II skeletal malocclusion from Universitas Airlangga Dental Hospital, between April 2015 and 2016. Cephalometric analysis was performed using digital software by a single examiner. This analysis measured gonial (Go), upper gonial (Go₁), lower gonial (Go₂), Yaxis-SN angle, the length of anterior face height, and posterior face height. The correlation between each variable was analyzed using the Pearson correlation test (P<0.01).

Results

There was a correlation between vertical components and Class II skeletal malocclusion.

Conclusion

Vertical components were correlated with Class II skeletal malocclusion. The greater ANB angle will be followed by greater Go₂, which worsens the condition of Class II skeletal malocclusion.

Long-term follow-up and treatment of a patient with severe skeletal open bite using temporary anchorage devices

This case report presents the treatment and long-term follow-up of a patient with severe skeletal hyperdivergent open bite, Class II malocclusion, and a severely retruded chin. After failure of early treatment using high-pull headgear with a bite block during the early permanent dentition stage due to an unfavorable growth pattern, orthognathic surgery was proposed but rejected by the patient. Then, temporary anchorage devices were used to correct the occlusion and establish an acceptable overbite and overjet. The overall observation time was 8.5 years; the treatment time using fixed appliances was 3 years and 4 months. The achieved tooth position and occlusal relationship remained stable 2.5 years later without recurrence of the open bite.

Geometric morphometric analysis of craniofacial growth between the ages of 12 and 14 in normal humans

Aim

There is great variation of growth among individuals. The question whether patients with different skeletal discrepancies grow differently is biologically interesting but also important in designing clinical trials. The aim of the present study was to evaluate whether growth direction depends on the initial craniofacial pattern.

Subjects and method

The sample consisted of 350 lateral cephalograms of 175 subjects (91 females and 84 males) followed during normal growth without any orthodontic treatment. The examined ages were 12 (T1) and 14 (T2) years. The cephalograms were obtained from the American Association of Orthodontists Foundation (AAOF) Craniofacial Growth Legacy Collection (Burlington, Fels, Iowa, and Oregon growth studies). We digitally traced 15 curves on each cephalogram, comprehensively covering the craniofacial skeleton, and located 127 points on the curves, 117 of which were sliding semilandmarks and 10 fixed. Procrustes alignment, principal component analysis and two-block partial least squares analysis were performed, after sliding the semilandmarks to minimize bending energy.

Results

The first 10 principal components (PCs) described approximately 71 per cent of the total shape variance. PC1 was related to shape variance in the vertical direction (low/high angle skeletal pattern) and PC2 was mainly related to shape variance in the anteroposterior direction (Class II/Class III pattern). PC3 was mainly related to the shape variance of the mandibular angle. All subjects shared a similar growth trajectory in shape space. We did not find any correlation between the initial shape and the magnitude of shape change between T1 and T2, but males showed a greater shape change than females. The direction of shape change was moderately correlated to the initial shape (RV coefficient: 0.14, P < 0.001).

Conclusions

The initial shape of the craniofacial complex covaried weakly with the direction of shape change during growth.

Mandibular canal changes assessed using three-dimensional imaging (CBCT)

INTRODUCTION

To identify changes in the adolescent mandibular canal (MC) using cone-beam computer tomography (CBCT) by locating three-dimensional (3D) anatomical landmarks in the mandible for later growth and treatment applications.

METHODS

Two CBCT images taken 1.5-2 years apart for 50 patients (ages 11-17) were landmarked using AVIZO^®. Six core landmarks were placed relative to the right and left MCs. Three-dimensional coordinates (x, y, z) were obtained. Average distances between paired landmarks were measured using a paired samples t-test. Mean distance differences <1.50mm were determined clinically insignificant and stable. To determine landmark position consistency, repeat CBCTs from 11 patients were landmarked three times one week apart. Coordinates were determined and intra-class correlation coefficient statistics (ICC), mean error difference and confidence intervals were measured.

RESULTS

X and y-coordinates had an internal consistency of 1.00. Z-coordinates had a consistency of 0.995 or higher. Measurement error was <1mm. The largest mean distance change was 2.25mm±3.06mm between the right mandibular foramen and the landmark directly on the right canal, closest to the mesial root of the first molar. The smallest mean distance change was <0.01mm±1.7mm between the right and left mental foramina. Additionally, the bilateral mandibular foramina, bilateral distal and mesial roots of the first molar, and bilateral regions on the MC inferior to both distal and mesial roots of the first molar were stable.

CONCLUSION

All landmarks were determined reliable. The region between the right and left mental foramina was found most stable for this time period in adolescents.

Morphometric analysis of shape differences in Windover and Point Hope archaic human mandibles

OBJECTIVES

The mandible can provide valuable information on both the life history and genetic makeup of Archaic human populations. The following analysis tests two hypotheses: (a) that there are significant differences in morphology in mandibular shape between the genders amongst Archaic North American Homo sapiens and (b) that there is a significant difference in variance in mandibular shape between Archaic Windover and Point Hope.

MATERIALS AND METHODS

A sample made from mandible specimens taken from both populations is subjected to Principal Component Analyses (PCA). The component scores from the PCAs are subjected to both a Multivariate Analysis of Covariance (mancova) and a general Multivariate Analysis of Variance (manova) to determine whether significant differences in variance exist between the sexes and the populations.

RESULTS

The mancova found that there are no significant interactions between the PC scores in population, sex, or size. Significant differences in variance were found between males and females and between the Windover and Point Hope populations.

CONCLUSIONS

Differences in variance observed between the populations are suspected to be due to differences in subsistence strategies and possibly non-masticatory utilizations of teeth. Differences in variance between the genders are suspected to be genetic in origin.

PLXNA2 identified as a candidate gene by genome-wide association analysis for mandibular prognathism in human chondrocytes

In a previous genome-wide association study, plexin A2 (PLXNA2) was suggested as one of the candidate genes for mandibular prognathism. PLXNA2 encodes plexin A2, a member of the plexin-A family of semaphorin co-receptors. Semaphorin 3A (sema3A) exerts an osteoprotective effect. However, to the best of our knowledge, there have been no previous studies examining the role of sema3A or plexin A2 on human chondrocytes. The objectives of the present study were to examine the function of sema3A and its receptor, plexin A2, in human chondrocytes. Normal human chondrocytes were cultured in media with either a high (100 ng/ml) or a low (1 ng/ml) concentration of sema3A, or without sema3A as a control. Cells and extracellular matrices were assayed for concentrations of protein and parathyroid hormone-related peptide receptor 1 (PTH-R1) using a bicinchoninic acid assay and an enzyme immunoassay, respectively. At culture day 7, the high and low concentrations of exogenous sema3A significantly increased the protein content compared with the control (P=0.0008 and 0.00002, respectively). At culture day 14, a high concentration of exogenous sema3A significantly increased the protein content and decreased the concentration of PTH-R1 compared with the control (P=0.002). The present study revealed novel results that exogenous sema3A suppresses the expression of PTH-R1 in human proliferative chondrocytes and suggested that sema3A may affect human chondrocytes via its receptor, plexin A2.

Assessment of lower incisor alveolar bone width using cone-beam computed tomography images in skeletal Class III adults of different vertical patterns

Objective

This study was performed to investigate the alveolar bone of lower incisors in skeletal Class III adults of different vertical facial patterns and to compare it with that of Class I adults using cone-beam computed tomography (CBCT) images.

Methods

CBCT images of 90 skeletal Class III and 29 Class I patients were evaluated. Class III subjects were divided by mandibular plane angle: high (SN-MP > 38.0°), normal (30.0° < SN-MP < 37.0°), and low (SN-MP < 28.0°) groups. Buccolingual alveolar bone thickness was measured using CBCT images of mandibular incisors at alveolar crest and 3, 6, and 9 mm apical levels. Linear mixed model, Bonferroni post-hoc test, and Pearson correlation analysis were used for statistical significance.

Results

Buccolingual alveolar bone in Class III high, normal and low angle subjects was not significantly different at alveolar crest and 3 mm apical level while lingual bone was thicker at 6 and 9 mm apical levels than on buccal side. Class III high angle group had thinner alveolar bone at all levels except at buccal alveolar crest and 9 mm apical level on lingual side compared to the Class I group. Class III high angle group showed thinner alveolar bone than the Class III normal or low angle groups in most regions. Mandibular plane angle showed negative correlations with mandibular anterior alveolar bone thickness.

Conclusions

Skeletal Class III subjects with high mandibular plane angles showed thinner mandibular alveolar bone in most areas compared to normal or low angle subjects. Mandibular plane angle was negatively correlated with buccolingual alveolar bone thickness.

Class II subdivision correction with clear aligners using intermaxilary elastics

BACKGROUND

To describe an esthetic orthodontic treatment using aligners in an adult patient with class II subdivision associated with crowding and dental crossbite. An 18-year-old hyperdivergent male patient with skeletal class II from mandibular retrusion presented for an orthodontic treatment. Occlusally, the patient presents class II subdivision, crossbite at tooth 4.4, an upper midline deviated towards the left with respect to the lower and facial midlines, and slight crowding in both arches. The patient refused conventional fixed multibracket treatment in favor of aligners. Pre- and post-treatment records as well as 1-year follow-up records are presented.

FINDINGS

Treatment objectives were achieved in 12 months, and the patient was satisfied with the functional and esthetic outcomes, which were stable at 1 year.

CONCLUSION

Combining aligners with appropriate auxiliaries is an efficacious means of resolving orthodontic issues such as class II, dental crossbite, and crowding in a time-frame comparable to that of conventional fixed orthodontics. Furthermore, this system is associated with optimal oral hygiene and excellent esthetics.

Developing Class III malocclusions: challenges and solutions

Class III malocclusion represents a growth-related dentofacial deformity with mandibular prognathism in relation to the maxilla and/or cranial base. Its prevalence varies greatly among and within different races, ethnic groups, and geographic regions studied. Class III malocclusion has a multifactorial etiology, which is the expression of a moderate distortion of normal development as a result of interaction between innate factors or genetic hereditary with environmental factors. Various skeletal topographies of underlying Class III malocclusion are due to discrepancy in the maxillary and mandibular growth along with vertical and/or transverse problems apart from sagittal malformations. The spectrum of complications for Class III malocclusion ranges in gravity from dentoalveolar problems with functional anterior shift of the mandible to true skeletal problems with serious maxillomandibular discrepancies, which makes its diagnosis highly challenging in growing children. Concern regarding early treatment and the need for interceptive care in the case of Class III malocclusion has always been a dilemma, knowing that not all problems will be solved in these cases until maxillomandibular growth is further completed, and the long-term outcome of various treatment approaches may depend on the growth tendency of an individual. Interceptive treatment of Class III malocclusions should be undertaken if it prevents damage to the oral tissues and/or significantly reduces the amount or severity of future orthodontic and surgical interventions. This paper presents an overview of developing Class III malocclusion, with the emphasis on challenges and their solutions based on the best current available evidence.

Non-orthodontic intervention and non-nutritive sucking behaviours: A literature review

Anterior open bite (AOB) is one of the most complex malocclusions to manage. AOB is caused by either by skeletal, genetic or environmental factors. Numerous treatment options are currently utilised to manage AOB. These vary from non-invasive behavioural shaping to orthodontic and surgical interventions. This paper reviews the available orthodontic and non-orthodontic interventions used in the management of AOB. The literature review was carried out using the PubMed search engine from the first of January 2000 to the first of June 2017. Two major keywords (open bite and anterior open bite) were used in addition to 23 minor keywords in the review. AOB is one of the most complex malocclusions to treat with high relapse rates. Long term outcome in treatments of patients with AOB was substantially low. Relapse rates were not taken into consideration for some of the literature reviewed. Despite limitations of the literature, it is recommended that orofacial myofunctional therapy (OMT) and non-orthodontic intervention (NOI) be used in conjunction as an effective treatment option for Anterior Open Bite.

Is Counterclockwise Rotation With Double Jaw Orthognathic Surgery Stable in the Long-Term in Hyperdivergent Class III Patients?

PURPOSE

To evaluate the long-term postsurgical stability of counterclockwise rotation of the occlusal plane (OP) in double-jaw orthognathic surgery in patients with hyperdivergent Class III malocclusion.

MATERIALS AND METHODS

This retrospective cohort study evaluated the postsurgical stability of orthognathic surgery in patients with skeletal Class III malocclusion and counterclockwise rotation of the maxillomandibular complex with an OP change of at least -2°. Patients were evaluated with lateral cephalometric analysis before surgery, immediately after surgery, and at longest follow-up. The primary predictor variable was the change in angle of the OP and the Frankfort horizontal (FH) after surgery. The primary outcome variable was stability of the OP at longest follow-up. Other study variables were age, gender, and the following cephalometric measurements: mandibular plane angle; gonial angle; angle formed by the sella, nasion, and B point; maxillary height; angle of the palatal plane to the line connecting the sella and nasion; and distances of the posterior nasal spine and A point to the FH and of the A point to the vertical line passing from the nasion. The Mann-Whitney U test was used to compare stability between groups because the variables were not normally distributed. Bonferroni correction was used to evaluate P values. The χ² test and Fisher exact test, where appropriate, were used to compare the proportions of groups. A P value less than .05 was accepted as statistically significant.

RESULTS

The sample was composed of 15 adult patients (mean age at surgery, 23.5 yr; 40% men). The median duration of follow-up was 48 months (interquartile range, 36 to 60 months). The groups had similar demographic properties and similar surgical changes. Ten patients showed very stable results with an OP-FH change no greater than 1°. Four patients showed unstable results with an OP-FH change of 2.25 ± 0.5° during the follow-up period. The change in the mandibular plane angle was notable between patients with stability and those with instability, which was the variable most affected by relapse of the OP.

CONCLUSION

This study found long-term postsurgical skeletal stability of counterclockwise rotation of the OP during double-jaw orthognathic surgery in patients with high angle Class III malocclusion after a median follow-up of 48 months.

A Novel Registration-Based Semiautomatic Mandible Segmentation Pipeline Using Computed Tomography Images to Study Mandibular Development

OBJECTIVE

We present a registration-based semiautomatic mandible segmentation (SAMS) pipeline designed to process a large number of computed tomography studies to segment 3-dimensional mandibles.

METHOD

The pipeline consists of a manual preprocessing step, an automatic segmentation step, and a final manual postprocessing step. The automatic portion uses a nonlinear diffeomorphic method to register each preprocessed input computed tomography test scan on 54 reference templates, ranging in age from birth to 19 years. This creates 54 segmentations, which are then combined into a single composite mandible.

RESULTS

This pipeline was assessed using 20 mandibles from computed tomography studies with ages 1 to 19 years, segmented using both SAMS-processing and manual segmentation. Comparisons between the SAMS-processed and manually-segmented mandibles revealed 97% similarity agreement with comparable volumes. The resulting 3-dimensional mandibles were further enhanced with manual postprocessing in specific regions.

CONCLUSIONS

Findings are indicative of a robust pipeline that reduces manual segmentation time by 75% and increases the feasibility of large-scale mandibular growth studies.

Maternal environment and craniofacial growth: geometric morphometric analysis of mandibular shape changes with in utero thyroxine overexposure in mice

An estimated 3% of US pregnancies are affected by maternal thyroid dysfunction, with between one and three of every 1000 pregnancies being complicated by overactive maternal thyroid levels. Excess thyroid hormones are linked to neurological impairment and excessive craniofacial variation, affecting both endochondral and intramembranous bone. Using a geometric morphometric approach, this study evaluates the role of in utero thyroxine overexposure on the growth of offspring mandibles in a sample of 241 mice. Canonical variate analysis utilized 16 unilateral mandibular landmarks obtained from 3D micro-computed tomography to assess shape changes between unexposed controls (n = 63) and exposed mice (n = 178). By evaluating shape changes in the mandible among three age groups (15, 20 and 25 days postnatal) and different dosage levels (low, medium and high), this study found that excess maternal thyroxine alters offspring mandibular shape in both age- and dosage-dependent manners. Group differences in overall shape were significant (P < 0.001), and showed major changes in regions of the mandible associated with muscle attachment (coronoid process, gonial angle) and regions of growth largely governed by articulation with the cranial base (condyle) and occlusion (alveolus). These results compliment recent studies demonstrating that maternal thyroxine levels can alter the cranial base and cranial vault of offspring, contributing to a better understanding of both normal and abnormal mandibular development, as well as the medical implications of craniofacial growth and development.

Ethnic differences in craniofacial and upper spine morphology in children with skeletal Class II malocclusion

OBJECTIVES

To analyze differences in upper cervical spine and craniofacial morphology, including posterior cranial fossa and growth prediction signs, between Danish and South Korean pre-orthodontic skeletal Class II children and to analyze associations between upper cervical spine morphology and craniofacial characteristics.

MATERIALS AND METHODS

One hundred forty-six skeletal Class II children-93 Danes (54 boys and 39 girls, mean age 12.2 years) and 53 Koreans (27 boys and 26 girls, mean age 10.8 years)-were included. Upper spine morphology, Atlas dimensions, and craniofacial morphology, including posterior cranial fossa and growth prediction signs, were assessed on lateral cephalograms. Differences and associations were analyzed by multiple linear and logistic regression analyses adjusted for age and gender.

RESULTS

Significant differences between the ethnic groups were found in the sagittal and vertical craniofacial dimensions ( P < .001), mandibular shape ( P < .01), dental relationship ( P < .01), posterior cranial fossa ( P < .05), and growth prediction signs ( P < .001). No significant differences were found in upper spine morphology and Atlas dimensions between the groups. Upper spine morphology/dimensions were significantly associated with the cranial base angle ( P < .01), sagittal craniofacial dimensions ( P < .001), posterior cranial fossa ( P < .001), and growth prediction signs ( P < .05).

CONCLUSIONS

Upper spine morphology/dimensions may be valuable as predictive factors in treatment planning for growing Class II children.

Predictors of favorable soft tissue profile outcomes following Class II Twin-block treatment

OBJECTIVE

The aim of this study was to determine cephalometric factors that help predict favorable soft-tissue profile outcomes following treatment with the Class II Twin-block appliance.

METHODS

Pre- and post-treatment lateral cephalograms of 45 patients treated with the Class II Twin-block appliance were retrospectively analyzed. Profile silhouettes were drawn from the cephalograms and evaluated by three orthodontists in order to determine the extent of improvement. Samples were divided into a favorable group (upper 30% of visual analogue scale [VAS] scores, n = 14) and an unfavorable group (lower 30% of VAS scores, n = 14). Skeletal and soft-tissue measurements were performed on the cephalograms and an intergroup comparison was conducted.

RESULTS

An independent t-test revealed that the following pre-treatment values were lower in the favorable group compared to the unfavorable group: lower incisor to mandibular plane angle, lower incisor to pogonion distance, point A-nasion-point B angle, sella-nasion line (SN) to maxillary plane angle, SN to mandibular plane angle, gonial angle, and symphysis inclination. The favorable group had a larger incisor inclination to occlusal plane. Moreover, the favorable group showed larger post-treatment changes in gonial angle, B point projection, and pogonion projection than did the unfavorable group.

CONCLUSIONS

Class II malocclusion patients with a low divergent skeletal pattern and reduced lower incisor protrusions are likely to show more improvement in soft-tissue profile outcomes following Class II Twin-block treatment.

Maxillary and Mandibular Displacement in Hemifacial Microsomia: A Longitudinal Roentgen Stereometric Study of 21 Patients with the Aid of Metallic Implants

Objective

To record maxillary and mandibular displacement with articular growth and in response to bimaxillary surgical repositioning in patients with hemifacial microsomia (HFM) and to observe ipsilateral corpus/ramus growth in severely affected children.

Design

Prospective roentgen stereometric analysis (mean age 7 years 10 months to 18 years 0 months) and retrospective profile and panoramic roentgenograms. Mean total observation period was 9 years 1 month.

Setting

Department of Plastic and Reconstructive Surgery, Malmö University Hospital (Malmö, Sweden).

Patients

Twenty-one patients consecutively diagnosed from 1976 through 1988 with HMF, five of whom had bimaxillary surgery.

Interventions

Surgery was performed at the Department of Plastic and Reconstructive Surgery. Implants were inserted at the initial reconstructive surgical procedure under general anesthesia. Roentgen examinations were performed in connection with continued clinical evaluations and treatment.

Main Outcome Measures

Stereo roentgenograms were digitized at the Department of Orthopedic Surgery, Malmö University Hospital (Malmö, Sweden).

Results

Displacement of the jaws with articular growth and in response to bimaxillary surgical repositioning varied interindividually with no apparent common pattern. Relapse displacement occurred several years after bimaxillary surgery. Mandibular growth changes were found in the corpus/ramus area and alveolar process on the affected side.

Conclusions

A marked interindividual variability of maxillary and mandibular displacement indicates that the relevance of statistical analysis of HFM growth data may be questioned. We would suggest that precise and accurate longitudinal recordings of growth and response to surgery in individual HFM patients be more appropriate.

Herbst appliance with skeletal anchorage versus dental anchorage in adolescents with Class II malocclusion: study protocol for a randomised controlled trial

Background

The Herbst appliance is an orthodontic appliance that is used for the correction of class II malocclusion with skeletal discrepancies. Research has shown that this is effective. However, a potential harm is excessive protrusion of the lower front teeth. This is associated with gingival recession, loss of tooth support, and root resorption. This trial evaluates a method of reducing this problem.

Methods/Design

The study is a single-center, randomised, assessor-blinded, superiority clinical trial with parallel 1:1 allocation. Male and female young people (10–14 years old) with prominent front teeth (class II, division 1) will be treated in one orthodontic clinic. Group 1 will be treated with the conventional Herbst appliance with dental anchorage and group 2 with the Herbst appliance with indirect skeletal anchorage for 12 months. The primary objective will be to compare the proclination of the lower incisors between the Herbst appliance with dental anchorage and skeletal anchorage. Secondary objectives will be to evaluate the changes occurring between the groups in the mandible, maxilla, lower and upper molars, and in gingival recession and root resorption at the end of the treatment. Additionally, the young patient’s experience using the appliances will be assessed. The primary outcome measure will be the amount of lower incisor proclination at the end of treatment. This will be assessed by cone-beam computed tomography (CBCT) superimposition. Secondary outcome measures will be the changes in the mandible, maxilla, lower and upper molars at the end of treatment assessed by tomography superimposition and the young patient’s experience using the appliances assessed by self-reported questionnaires and semi-structured interviews. The randomisation method will be blocked randomisation, using software to generate a randomised list. The allocation concealment will be done in opaque envelopes numbered from 1 to 40 containing the treatment modality. The randomisation will be implemented by the secretary of the Department of Orthodontics of Rio de Janeiro State University before the beginning of the study. The patients and the orthodontists who will treat the patients cannot be blinded, as they will know the type of appliance used. The technician who will take the CBCT image and the data analyst will be blinded to patients’ group allocation.

Discussion

If this new intervention is effective, the findings can change orthodontic practice and may also be relevant to other forms of treatment in which appliances are fixed to the bones of the jaws. However, if the bone anchoring is not effective, the trial will provide much needed information on the use of this comparatively new development.

Trial registration

ClinicalTrials.gov, protocol ID: NCT0241812. Registered on 26 March 2015.

Electronic supplementary material

The online version of this article (doi:10.1186/s13063-017-2297-5) contains supplementary material, which is available to authorized users.

Influence of orthodontic premolar extraction therapy on the eruption of the third molars: A systematic review of the literature

BACKGROUND

Through a systematic literature review, the authors assess the effect of premolar extractions on third-molar (M3) eruption considering eruption rate, retromolar space, and molar angulation.

TYPES OF STUDIES REVIEWED

The authors performed a systematic search using MEDLINE and Web of Science databases up through April 2017 to identify quality studies available comparing M3 eruption between a group with premolar extraction and a group without premolar extraction.

RESULTS

Twelve comparative retrospective cohort studies met all the inclusion criteria. The authors found in 5 studies comparing the rate of M3 eruption that there were significantly higher results in the group with extractions. They found in 5 studies comparing the evolution of the retromolar space significantly higher results in the group with extractions. Lastly, concerning the uprighting of the M3 during treatment, the authors found only 2 studies showing significant differences between the 2 groups, each time in favor of the group with extractions.

CONCLUSIONS AND PRACTICAL IMPLICATIONS

The dental literature on premolar extraction related to the eruption of the M3 is composed of average-quality retrospective studies. Premolar extraction significantly improves the chances of M3 eruption, but the level of evidence of comparative retrospective cohort studies is low. Clinicians must continue to rely on their judgment regarding premolar extraction on a case-by-case basis until the evidence is stronger. Retrospective studies with standardized protocols and more detailed methodologies are required to obtain higher levels of evidence.

Genome-wide association study for mandibular prognathism using microsatellite and pooled DNA method

INTRODUCTION

The purpose of this study was to extend an association study from chromosome 1 to the whole genome (genome-wide association study) to find susceptibility loci of mandibular prognathism.

METHODS

Two hundred forty patients diagnosed with mandibular prognathism and 360 healthy controls of Japanese descent were recruited. The typing of microsatellites covering the whole genome was conducted using a pooled DNA method. Upon completion of the first and second screenings with pooled DNA, the positive microsatellite markers from both the first and second typings were retyped using individual-subject DNA samples to confirm the significance of allele frequency.

RESULTS

Six microsatellites (D1S0411i, D1S1358i, D3S0810i, D6S0827i, D7S0133i, and D15S0154i) showed differences between allele frequencies of the subjects and controls at P <0.001. D1S0411i, D1S1358i, D3S0810i, D6S0827i, D7S0133i, and D15S0154i were located on chromosomes 1p22.3, 1q32.2, 3q23, 6q23.2, 7q11.22, and 15q22.22, respectively. SSX2IP, PLXNA2, RASA2, TCF21, CALN1, and RORA were suggested as candidate genes.

CONCLUSIONS

The genome-wide association study using microsatellites suggested that 6 loci (1p22.3, 1q32.2, 3q23, 6q23.2, 7q11.22, and 15q22.22) were susceptibility regions of mandibular prognathism. The locus 1p22.3 was supported by a previous linkage analysis, and the other 5 were novel loci.

Alveolar ridge atrophy related to facial morphology in edentulous patients

OBJECTIVES

The morphology of the alveolar process determines the retention and stability of prosthetic restorations, thereby determining the result of the therapy. Considering that the edentulous jaws may be affected by the atrophy process, it was hypothesized that the morphology of the alveolar process of the maxilla may be dependent on the anterior facial height and anatomy of the mandible.

SUBJECTS AND METHODS

Twenty-five healthy edentulous Caucasian individuals were randomly chosen. Each subject underwent a lateral cephalogram before and after prosthetic rehabilitation. During exposition, newly made prostheses were placed in the patient's mouth. Teeth remained in maximal intercuspidation. Morphological parameters were evaluated according to the Ricketts, McNamara, and Tallgren's method.

RESULTS

An inversely proportional association was observed between patient age and the distal part of the maxilla. A statistically significant connection was noted between the vertical dimension of alveolar ridge and anterior total and lower facial height conditioned by prosthetic rehabilitation.

CONCLUSION

The height of the lateral part of the alveolar ridge of the maxilla remains in connection with the anterior total and lower facial height obtained in the course of prosthetic rehabilitation. The vertical dimension of the alveolar ridge of the maxilla seems to be in close relationship with the morphology of the lower jaw.

To Evaluate the Correlation Between Skeletal and Dental Parameters to the Amount of Crowding in Class II Div. 1 Malocclusions

Introduction

Crowding of teeth is one of the most common problem that motivates the patient to seek orthodontic treatment. Determination of etiology of crowding could have a significant effect on treatment planning and prognosis of Class II malocclusion.

Aim

Aim of this study was to evaluate the relationship of skeletal and dental parameters to amount of dental crowding in patients with Class II Divison 1 (div.1) malocclusion.

Materials and Methods

Pretreatment lateral cephalograms and dental casts of 60 patients with skeletal Class II malocclusion were collected for the study. The sample was divided into two groups according to severity of pretreatment mandibular crowding. Group I consisted of cases with crowding ≥3 mm and Group II with crowding <3 mm. Lateral cephalograms for each patient was manually traced and skeletal parameters (effective maxillary and mandibular length, mandibular plane angle, Y Axis, lower anterior face height) and dental parameters (axial inclination of lower incisor, inclination of lower incisor to mandibular plane, interincisal angle) were measured. Unpaired t-test was used for intergroup comparison and relationship between different measurements was investigated using Pearson correlation coefficient.

Results

Among the skeletal parameters measured, only effective mandibular length exhibited statistically significant difference between the two groups. No statistically significant difference was found between the two groups for any of the dental parameters. Significant inverse correlation was found between mandibular crowding and effective mandibular length.

Conclusion

Subjects with Class II div.1 malocclusion and moderate to severe mandibular crowding have significantly smaller effective mandibular base length than subjects with the same malocclusion and slight mandibular crowding.

Principles of Orthognathic Surgical Correction of Skeletal Anterior Open Bite

This article describes the principles of orthognathic surgical correction of skeletal anterior open bite (AOB), including a description of the aetiological factors involved in the development of predominantly skeletal AOBs, description of the presenting diagnostic features, the principles of treatment planning, orthodontic preparation, and postoperative requirements.