The heritability of malocclusion: part 2. The influence of genetics in malocclusion

Impact of Malocclusions on Periodontopathogenic Bacterial Load and Progression of Periodontal Disease: A Quantitative Analysis

BACKGROUND

(1) Periodontal disease (PD) is a globally prevalent chronic inflammatory condition, exacerbated by the dysbiosis of the oral microbiota. This study aims to evaluate the bacterial load of specific periodontopathogenic bacteria in patients with malocclusions (MAL) compared to those without. (2) Methods: Conducted at the "Carol Davila" University of Medicine and Pharmacy, Bucharest, Romania, this pilot study involved two groups: patients with MAL and PD, and patients with PD but without MAL. We included 20 patients: 10 with MAL (9 with crowding and 1 with an open bite) and 10 without MAL. Gingival crevicular fluid was collected for bacterial DNA extraction and quantified bacterial load using real-time PCR, focusing on 12 periodontopathogenic bacteria across different complexity classes. (3) Results: The study identified significantly higher concentrations of Treponema denticola (p = 0.023, median = 4.32, IQR = 2.76-5.53 vs. median = 1.93, IQR = 0-3.19), Tannerella forsythia (p = 0.020, mean = 6.04 ± 0.72 vs. mean = 4.4 ± 1.89) and Porphyromonas gingivalis (p = 0.002, median = 5.64, IQR = 4.94-5.98 vs. median = 2.48, IQR = 0-4.05) in patients with MAL compared to those without. This suggests that MAL contributes to an environment conducive to the proliferation of specific pathogens, potentially accelerating PD progression. Additionally, Eikenella corrodens (p = 0.040, mean = 4.55 ± 1.02 vs. mean = 3.23 ± 1.56), Campylobacter rectus (p < 0.001, mean = 4.2 ± 0.56 vs. mean = 1.8 ± 1.51), Prevotella intermedia (p = 0.043, median = 5.04, IQR = 0-5.49 vs. median = 0, IQR = 0-3.39), Capnocytophaga sputigena (p = 0.011, median = 5.91, IQR = 5.47-6.17 vs. median = 4.63, IQR = 3.83-5.64), and Capnocytophaga gingivalis (p = 0.007, median = 5.87, IQR = 5.34-6.03 vs. median = 4.4, IQR = 3.5-5.71) also showed elevated concentrations, indicating the broad impacts of MAL on oral microbial profiles. (4) Conclusions: The findings demonstrate a significant relationship between MAL and increased bacterial loads, underscoring the need for its integration in managing PD. Future research should expand demographic diversity and employ longitudinal designs to better understand the causative mechanisms at play.

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.

The Prevalence of Malocclusion and Orthodontic Treatment Need in 13-15 Years Old School Going Children of Mehsana District, Gujarat: An Epidemiological Study

Aim

The current study's objective was to find out the prevalence of malocclusion and the need for orthodontic treatment in 13- to 15-year-old school students in the Mehsana District of Gujarat using the IOTN.

Materials and Methods

A descriptive cross-sectional epidemiological survey was planned among 13- to 15-year-old school-going children of Mehsana district. The sample comprised of 1290 school children. DHC-IOTN was applied to evaluate normative need for orthodontic treatment. Perceived orthodontic treatment was described by the Aesthetic component of the IOTN index.

Results

Results showed that 33.7 percent of participants required little/no treatment need, 43.9 percent of participants required moderate orthodontic treatment need, and 22.4 percent of participants required severe orthodontic treatment need in the district.

Conclusion

To prepare for public orthodontic and dental services, the current study provides baseline data on the need for orthodontic treatment among school-aged children.

Heritability of dental arches and occlusal characteristics: a systematic review and meta-analysis

BACKGROUND AND OBJECTIVE

The genetic basis of dentoalveolar characteristics has been investigated by several studies, however, the findings are equivocal. The objective of this systematic review and meta-analysis was to evaluate the heritability of dental arches and occlusal parameters in different stages of human dentition.

SEARCH METHODS

Electronic databases PubMed, Embase, Scopus, Web of Science, and Dentistry and Oral Science Source were searched up to August 2023 without the restriction of language or publication date.

SELECTION CRITERIA

Empirical studies investigating the heritability of dentoalveolar parameters among twins and siblings were included in the review.

DATA COLLECTION AND ANALYSIS

Study selection, data extraction, and risk of bias assessment were performed independently and in duplicate by two authors and a third author resolved conflicts if needed. Joanna Briggs Institute's critical appraisal tool was used to evaluate the risk of bias among studies and the certainty of evidence was assessed using the Grading of Recommendation, Assessment, Development, and Evaluation (GRADE) criteria.

RESULTS

Twenty-eight studies were included in the systematic review, of which 15 studies reporting heritability coefficients in the permanent dentition stages were deemed suitable for the meta-analysis. Random-effects meta-analyses showed high heritability estimates for maxillary intermolar width (0.52), maxillary intercanine width (0.54), mandibular intermolar width (0.55), mandibular intercanine width (0.55), maxillary arch length (0.76), mandibular arch length (0.57), and palatal depth (0.56). The heritability estimates for the occlusal parameters varied considerably, with relatively moderate values for crossbite (0.46) and overbite (0.44) and low values for buccal segment relationship (0.32), overjet (0.22), and rotation and displacement of teeth (0.16). However, the certainty of evidence for most of the outcomes was low according to the GRADE criteria.

CONCLUSIONS

Based on the available evidence, it can be concluded that the dental arch dimensions have a high heritability while the occlusal parameters demonstrate a moderate to low heritability.

REGISTRATION

PROSPERO (CRD42022358442).

The contribution of genetics to dental caries, oral habits and occlusal traits in Turkish twins: A comparative study

OBJECTIVE

The aims of this study were to investigate and compare the prevalence of dental caries and the frequency of oral habits, molar relationships and occlusal traits between children of multiple births, and singletons, and to determine the relative contributions of genetics and environmental factors to these parameters by using twin study design.

METHODS

The study group consisted of 345 multiple births (34 monozygotic and 122 dizygotic twin pairs, 11 sets of triplets) and 345 singletons between the ages of 2 and 17. The prevalence of dental caries, and the frequency of tooth brushing, the children's oral habits, molar relationships, and occlusal traits were recorded.

RESULTS

The percentage of children who brushed their teeth more than twice daily was statistically significantly higher in multiple births than in singletons. Higher correlation coefficients were found in dental caries index, except for decayed, filled (df) (2-5 age group) and filled (f) (6-11 age group), in the monozygotic twin pairs compared to those in the dizygotic twin pairs. In children between the ages of 6 and 11 years, mouth breathing, bruxism, lip biting, and pencil biting were higher in singletons than in children of multiple births. There were statistically significant differences between children of multiple births and singletons, with increased overjet in the 2-5 year age group being observed.

CONCLUSION

When analyzing these parameters, environmental factors must also be investigated. Due to the low incidence of twin births, longitudinal follow-up studies with more twin pairs are necessary to determine whether these results are generalizable.

Effects of functional orthopedic treatment on mandibular trabecular bone in class II patients using fractal analysis

PURPOSE

The aim of this retrospective study was to evaluate the effects of functional orthopedic treatment on mandibular bone structure using fractal dimension (FD) analysis of panoramic radiographs.

METHODS

The study material consisted of the pre- and posttreatment digital panoramic radiographs of 80 patients (mean age 10.1 ± 2.01 years; 45 girls, 35 boys) with class II malocclusion who were treated with the monoblock or twin block appliances. The following regions of interest (ROI) were selected: ROI1, condylar process; ROI2, angulus mandibulae; ROI3, corpus mandibulae; and ROI4, mental foramen. Pre- and posttreatment FD values were compared for each ROI.

RESULTS

FD values of the mandibular condyle did not change with the functional orthodontic treatment. FD values of the mandibular corpus region had the highest pretreatment values and significantly decreased with treatment (p < 0.05).

CONCLUSION

Functional orthopedic treatment altered the trabeculation of the mandibular bone, but it is speculated that the changes in the occlusal forces seemed to be of primary significance for this effect.

Effect of the Correction of Bilateral Differences in Masseter Muscle Functional Pressure on the Mandible of Growing Rats

The objective of this study is to clarify the effect of restoring the lowered masticatory muscle functional pressure and correcting bilateral differences in masticatory muscle functional pressure on jawbone growth during growth and development with a quantitative evaluation of the changes in the micro/nanostructural characteristics of entheses. Male Wistar rats aged 4 weeks were divided into an experimental group injected with a botulinum toxin serotype A (BoNT/A) formulation to reduce muscle function (BTX group) and a control group (CTRL group). They were euthanised after 6, 8, 10, 12, and 16 weeks after measuring the difference between the midline of the upper and lower incisors. The mandibles were harvested for histological examination, second harmonic generation imaging, and the quantitative evaluation of biological apatite (BAp) crystal alignment. The midline difference decreased with age in weeks. In rats from 6 weeks after BoNT/A administration to 12 weeks after administration, the collagen fibre bundle diameter was significantly smaller in the BTX group; the difference between the two groups decreased with increasing age. BAp crystal alignment was significantly different on the x-axis and the y-axis on the BTX group from 6 weeks after BoNT/A administration to 10 weeks after administration. Asymmetry of mandibular bone formation caused by load imbalance during growth could be corrected by the adjustment of the function of the masseter muscle on either side.

Skeletal Class II Malocclusion: From Clinical Treatment Strategies to the Roadmap in Identifying the Genetic Bases of Development in Humans with the Support of the Collaborative Cross Mouse Population

Depending on how severe it is, malocclusion, which may involve misaligned teeth, jaws, or a combination of the two, can hurt a person's overall facial aesthetics. The maxillary molar develops before the mandibular molar in class II malocclusion, which affects 15% of the population in the United States. With a retrusive mandible, patients typically have a convex profile. The goal of this study is to classify the skeletal and dental variability present in class II malocclusion, to reduce heterogeneity, present the current clinical treatment strategies, to summarize the previously published findings of genetic analysis, discuss these findings and their constraints, and finally, propose a comprehensive roadmap to facilitate investigations aimed at determining the genetic bases of malocclusion development using a variety of genomic approaches. To further comprehend the hereditary components involved in the onset and progression of class II malocclusion, a novel animal model for class II malocclusion should be developed while considering the variety of the human population. To overcome the constraints of the previous studies, here, we propose to conduct novel research on humans with the support of mouse models to produce contentious findings. We believe that carrying out a genome-wide association study (GWAS) on a large human cohort to search for significant genes and their modifiers; an epigenetics-wide association study (EWAS); RNA-seq analysis; integrating GWAS and the expression of quantitative trait loci (eQTL); and the testing of microRNAs, small RNAs, and long noncoding RNAs in tissues related to the skeletal class II malocclusion (SCIIMO) phenotype, such as mandibular bone, gum, and jaw in humans and the collaborative cross (CC) mouse model, will identify novel genes and genetic factors affecting this phenotype. We anticipate discovering novel genetic elements to advance our knowledge of how this malocclusion phenotype develops and open the venue for the early identification of patients carrying the susceptible genetic factors so that we can offer early prevention treatment strategies.

Towards Genetic Dissection of Skeletal Class III Malocclusion: A Review of Genetic Variations Underlying the Phenotype in Humans and Future Directions

INTRODUCTION

Skeletal abnormalities and malocclusions have varied features that impact populations globally, impairing aesthetics and lowering life quality. The prevalence of the Skeletal Class III disease is the lowest among all angle malocclusions, with varied prevalence across nations. Environmental, genetic, and societal factors play a role in its numerous etiologies. In this study, we conducted a thorough search across the published data relating to quantitative trait loci (QTL) and the genes associated with Class III progression in humans, discussed these findings and their limitations, and proposed future directions and strategies for studying this phenotype.

METHODS

An inclusive search of published papers in the PubMed and Google Scholar search engines using the following terms: 1. Human skeletal Class III; 2. Genetics of Human skeletal Class III; 3. QTL mapping and gene associated with human skeletal Class III; 4. enriched skeletal Class-III-malocclusion-associated pathways.

RESULTS

Our search has found 53 genes linked with skeletal Class III malocclusion reported in humans, genes associated with epigenetics and phenomena, and the top 20 enriched pathways associated with skeletal Class III malocclusion.

CONCLUSIONS

The human investigations yielded some contentious conclusions. We conducted a genome-wide association study (GWAS), an epigenetics-wide association study (EWAS), RNA-seq analysis, integrating GWAS and expression quantitative trait loci (eQTL), micro- and small-RNA, and long non-coding RNA analysis in tissues connected to skeletal Class III malocclusion phenotype in tissues connected with the skeletal phenotype. Finally, we invite regional, national, and international orthodontists and surgeons to join this effort by contributing human samples with skeletal Class III malocclusion following the accepted Helsinki ethical protocol to challenge these phenomena jointly.

Comparative evaluation of dermatoglyphic patterns between skeletal class I and skeletal class III malocclusion

Background: Dermatoglyphics is the study of various dermal configurations on the fingers, palms, and soles. These appear during the 12th week of intrauterine life and develop completely by the 24th week. It is said that they remain constant thereafter. The aim of the present study was to compare and assess the association of dermatoglyphic patterns between skeletal class I and skeletal class III malocclusion. Methods: Finger and palm prints were collected using the ink and roller method from 604 subjects who were divided into skeletal class I, class III with maxillary retrognathism and class III with mandibular prognathism based on lateral cephalogram assessment. Results: Loop pattern was more predominant in skeletal class I malocclusion subjects and whorl pattern was more frequent in the other two groups. Total finger ridge count and atd angle also showed significant difference between the study groups. Conclusions: The present study attempted in assessing the association between dermatoglyphic patterns and skeletal malocclusion. Analysing dermal configurations may aid in indicating the type of developing malocclusion and thus help in interceptive and preventive orthodontics.

Evaluation of artificial intelligence model for crowding categorization and extraction diagnosis using intraoral photographs

Determining the severity of dental crowding and the necessity of tooth extraction for orthodontic treatment planning are time-consuming processes and there are no firm criteria. Thus, automated assistance would be useful to clinicians. This study aimed to construct and evaluate artificial intelligence (AI) systems to assist with such treatment planning. A total of 3,136 orthodontic occlusal photographs with annotations by two orthodontists were obtained. Four convolutional neural network (CNN) models, namely ResNet50, ResNet101, VGG16, and VGG19, were adopted for the AI process. Using the intraoral photographs as input, the crowding group and the necessity of tooth extraction were obtained. Arch length discrepancy analysis with AI-detected landmarks was used for crowding categorization. Various statistical and visual analyses were conducted to evaluate the performance. The maxillary and mandibular VGG19 models showed minimum mean errors of 0.84 mm and 1.06 mm for teeth landmark detection, respectively. Analysis of Cohen's weighted kappa coefficient indicated that crowding categorization performance was best in VGG19 (0.73), decreasing in the order of VGG16, ResNet101, and ResNet50. For tooth extraction, the maxillary VGG19 model showed the highest accuracy (0.922) and AUC (0.961). By utilizing deep learning with orthodontic photographs, dental crowding categorization and diagnosis of orthodontic extraction were successfully determined. This suggests that AI can assist clinicians in the diagnosis and decision making of treatment plans.

Genetics of three-dimensional tooth inclination and angulation in orthodontic patients with Class I Occlusion: A cross-sectional study

PURPOSE

This cross-sectional study aimed to utilize quantitative polymerase chain reaction (qPCR) to investigate the influence of genetic variance over teeth inclination and angulation in orthodontic patients with Class I occlusion.

MATERIALS AND METHODS

DNA was extracted from adolescent patients seeking orthodontic treatment in a single institution (from July 2018 to April 2020), who had CBCTs taken as part of initial standardized records. Patients had permanent dentition, Class I skeletal and dental classifications, with normal vertical and transverse skeletal dimensions, normal incisors inclination, no to mild crowding or spacing. qPCR was performed using genetic markers for candidate genes EPB41, TGFβ3, GHR and PAX9. Three-dimensional teeth inclinations (TI) and angulations (TA) were evaluated using Invivo6 software and correlated with genotypes. Reliability of TI and TA was assessed using intraclass correlation coefficients (ICC). Mixed models and multiple linear regression analyses were used to assess the association between each single nucleotide polymorphisms (SNP) with tooth inclination (TI) and with tooth angulation (TA). The results were evaluated at the significance level of P<0.05.

RESULTS

Twenty four adolescent patients with mean age of 13.4±2.4 years were included in the study. ICC showed adequate intra-examiner reliability for TI and TA (0.806<r<0.988, P<0.001). Multiple linear regression analysis showed a significant association between TI and homozygous-T polymorphism for PAX9 (P=0.028) and homozygous-G polymorphism for GHR (P=0.028). Also, a significant association between TA and homozygous-A polymorphism for EPB41 (P=0.019) and homozygous-G polymorphism for GHR (P=0.001) was evident.

CONCLUSIONS

Autosomal recessive patterns of inheritance for PAX9 and GHR with TI and for EPB41 and GHR with TA were shown. This study offers insight toward the hierarchical nature of epigenetic interactions between heredity and the environment in determining the three-dimensional positions of teeth in orthodontic patients with Class I occlusion.

Uniformity of palatal volume and surface area in various malocclusions

AIMS

To assess palatal volume, surface area and linear dimensions across sagittal and vertical components of malocclusion.

METHODS

Pre-treatment cephalographs and dental casts of 178 non-growing patients (88 males, 90 females, age 25.81 ± 8.23 years) were used for classification in sagittal malocclusion groups: Class I (n = 48), Class II division 1 (n = 42), Class II division 2 (n = 40) and Class III (n = 48); and in vertical divergence groups based on the MP/SN angle: hypodivergent (n = 35), normodivergent (n = 95) and hyperdivergent (n = 48). Dental casts were scanned and palatal measurements recorded: palatal width, depth and interdental distances; palatal surface area (PSA, mm² ) and volume (PV, mm³ ). A 3-way ANOVA was used to compare palatal dimensions across groups. Pearson product-moment correlations were employed to assess associations among variables.

RESULTS

PSA and PV (in both sex groups) were not statistically significantly different across sagittal malocclusions and vertical patterns. Significant differences were depicted more among the vertical divergence groups than sagittal groups. Correlations between PSA and PV and palatal dimensions were low to moderate. Predictability of PSA and PV ranged between 15 and 18%.

CONCLUSION

The finding of similar palatal volume and surface area, on average, across malocclusions possibly underscores the limitations of environmental influences within the inherited orofacial phenotype. The vertical facial pattern seems to be more interactive with palatal dimensions than sagittal relations. Studies of palatal changes following orthodontic and orthognathic treatments are warranted.

Management of a patient with a severely infraoccluded primary molar and hypodontia

Infraocclusion of a primary molar is a relatively common occurrence which seldom leads to serious complications, particularly when the succedaneous permanent tooth is present. Despite the relative infrequency of unfavorable outcomes, an infraoccluded primary molar may be associated with other dental anomalies, including hypodontia. If diagnosis is delayed, infraocclusion of a primary molar can become severe, with associated negative effects on the adjacent teeth and alveolar bone. This emphasizes the need for routine and periodic orthodontic assessment of growing patients. Any deviation from the normal eruption sequence of teeth should be diagnosed and managed in a timely manner, to preserve dental arch integrity and reduce the potential for undesirable outcomes. This case report demonstrates how comprehensive assessment of the dentition, logical treatment planning and careful management of challenging orthodontic tooth movements can combine to provide a pleasing treatment outcome.

Skeletal-dental features in 33 bull terrier dogs

Background

The Bull terrier breed has been reported in the veterinary literature to suffer frequent dental and skeletal malocclusions. In this retrospective case series, we report skeletal-dental anomalies in a group of 33 Bull terriers presented for a dental consultation.

Results

Out of 33 dogs examined, 24 cases had full mouth radiography or Cone-beam computed tomography performed. Eruption and development abnormalities observed were as follows: hypodontia in 54.1% (13/24), eruption changes in 29.2% (7/24), and tooth shape abnormalities in 33.3% (8/24). All dogs presented with some type of dental or skeletal malocclusion: neutroclusion was the most common (66.7% of the animals), followed by mandibular mesioclusion (18.8%), maxillo-mandibular asymmetry (9.4%), and mandibular distoclusion (6.3%). Dental abnormalities noted included rotation of mandibular and maxillary premolar teeth, distal displacement of the incisor teeth, lingual displacement of the mandibular canine teeth, and absence of mandibular premolar and molar teeth. Lingual displacement of mandibular canine teeth was associated with malocclusion causing trauma (odds ratio 7.1, 95% confidence interval [1.4 to 36.1], p = 0.024).

Conclusions

Malocclusions and tooth shape abnormalities were found to be the most frequent finding in this group of Bull terriers. Although these findings cannot be generalized to the global population further studies are needed to observe the true expression of these anomalies in the general breed population.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12917-022-03164-0.

Factors affecting willingness to pay for NHS-based orthodontic treatment

Objective To assess factors affecting willingness to pay for orthodontic treatment.Methods An online discrete choice experiment and willingness to pay study was conducted on a convenience sample of 250 participants aged 16 and above over a four-month period. Participants completed a series of stated-preference tasks, in which they viewed choice sets with two orthodontic treatment options involving different combinations of attributes: family income; cost to patient; cause of problem; prevention of future problems; age; severity of the problem; and self-esteem/confidence.Results Family income, cost to patient, cause of the problem, age and self-esteem/confidence were the most important attributes influencing participants' decisions to have orthodontic treatment. Participants felt that free NHS-based orthodontic provision should be prioritised for those under 18, regardless of family income, for those with developmental anomalies, particularly where self-esteem and confidence are affected, with younger participants (aged 16-24 years) strongly preferring full NHS funding for those under 18 years old (p = 0.007, 95% CI: 0.57-0.09) who dislike smiling in public, especially where self-esteem and confidence are impaired (p = 0.002, 95% CI: 0.16-0.71). Participants with high annual income had the highest preference for the NHS to fund treatment regardless of income (p = 0.02, 95% CI: 0.13-1.47) and placed an onus on addressing developmental anomalies (p = 0.004, 95% CI: 0.22-1.15). In total, 159 (63.6%) of those who would undergo treatment were willing to pay for it, with the majority (88%) open to paying up to £2,000 and only three participants stating the NHS should not contribute towards the cost of orthodontic treatment.Conclusions Based on this pilot study, key factors influencing the decision to undergo treatment included family income, cost, the aetiology of malocclusion, age and self-esteem/confidence. It was felt that free NHS-based treatment should be given priority where self-esteem and confidence are impaired among young people. Further research to inform the priorities underpinning the provision of dental care and orthodontic treatment within the NHS is required.

Heritability of facial soft tissue growth in mono- and dizygotic twins at 12 and 17 years of age: A retrospective cohort study

OBJECTIVE

The purpose of this investigation of untreated monozygotic and dizygotic twins was to identify the genetic and environmental components to the facial soft tissue growth.

SETTINGS AND SAMPLE POPULATION

The sample consisted of 52 untreated monozygotic twins (36 male and 16 female) and 46 untreated dizygotic twins (23 male and 23 female) from the Forsyth Moorrees Twin Study (1959-1975).

MATERIALS AND METHODS

Lateral cephalograms were taken at 12 and 17 years of age and traced to analyse facial convexity, nasolabial angle, upper and lower lip thickness, upper and lower lip profile and nose prominence. The genetic and environmental components of variance were analysed with structural equation modelling for multilevel mixed-effects model.

RESULTS

At 12 years of age, strong additive genetic influence was seen for facial convexity (70%), upper lip profile (66%) and nose prominence (65%), whereas strong dominant genetic components were found for upper lip thickness (56%). Nevertheless, under unique environment influence were nasolabial angle (58%), lower lip profile (51%) and lower lip thickness (64%). At 17 years of age, only upper lip thickness (55%) and nose prominence (84%) were under strong additive genetic control, while the rest of the variables were under strong dominant genetic control. The only exception was lower lip thickness (61%), which is still influenced by the unique environment.

CONCLUSION

Although monozygotic/dizygotic twins share at least part of their genome, at both times either additive, dominant or environmental components were found. Nevertheless, at 17 years of age most of the variables are either under additive or dominant genetic influence.

Multivariate GWAS of Structural Dental Anomalies and Dental Caries in a Multi-Ethnic Cohort

Odontogenesis is a complex process, where disruption can result in dental anomalies and/or increase the risk of developing dental caries. Based on previous studies, certain dental anomalies tend to co-occur in patients, suggesting that these traits may share common genetic and etiological components. The main goal of this study was to implement a multivariate genome-wide association study approach to identify genetic variants shared between correlated structural dental anomalies and dental caries. Our cohort (N = 3,579) was derived from the Pittsburgh Orofacial Clefts Study, where multiple dental traits were assessed in both the unaffected relatives of orofacial cleft (OFC) cases (n = 2,187) and unaffected controls (n = 1,392). We identified four multivariate patterns of correlated traits in this data: tooth agenesis, impaction, and rotation (AIR); enamel hypoplasia, displacement, and rotation (HDR); displacement, rotation, and mamelon (DRM); and dental caries, tooth agenesis and enamel hypoplasia (CAH). We analyzed each of these four models using genome-wide multivariate tests of association. No genome-wide statistically significant results were found, but we identified multiple suggestive association signals (P < 10-5) near genes with known biological roles during tooth development, including ADAMTS9 and PRICKLE2 associated with AIR; GLIS3, WDR72, and ROR2 associated with HDR and DRM; ROBO2 associated with DRM; BMP7 associated with HDR; and ROBO1, SMAD2, and MSX2 associated with CAH. This is the first study to investigate genetic associations for multivariate patterns of correlated dental anomalies and dental caries. Further studies are needed to replicate these results in independent cohorts.

Clinical and Radiographical Evaluation of Non-syndromic Dental Anomalies in Turkish Children

AIM: The aim of this study was to investigate the frequency and distribution of non-syndromic developmental dental anomalies in Turkish children in different age groups. SUBJECTS AND METHODS: A sample of 516 children aged 3–17 years who attended the Pediatric Dentistry Department of Istanbul Aydin University were evaluated clinically and radiographically for the existence of any structural, shape, and number anomalies of the developing dentition, and the most prevalent anomalies were compared according to gender and age groups. RESULTS: The most observed dental anomaly was Molar Incisor Hypomineralization (MIH) and tooth agenesis by a percentage of 14.3% and 4.8%, respectively. The incidence of MIH was higher in 7–8 and 9–10 years of age groups. There were no anomalies detected in 361 (70%) of the patients; meanwhile, only one anomaly was observed in 110 (21.3%), two different anomalies at the same time were observed in 33 (6.4%), and more than two anomalies were observed in 12 (2.3%) in the study group. STATISTICS: The statistical analysis of the results was obtained using the IBM SPSS Statistics 22 (IBM SPSS, Inc USA) program. p < 0.05 was considered to be statistically significant. CONCLUSION: Although there are no known systemic disturbances, at least, one dental anomaly was observed in 21.3% of the children. The most observed anomalies were MIH and tooth agenesis. An increase in the MIH prevalence throughout the world may lead to the suggestion that more investigations should be made on environmental predisposing factors. Besides, there might be common genetic factors and genes (PAX9, AXIN2, MSX1) affecting both tooth development and tumor formation which may be a potential risk marker for future cancer development.

Does Appliance Design Affect Treatment Outcomes of Class II Division 1 Malocclusion? A Two-Center Retrospective Study

Objectives

The purpose of this retrospective study was to compare the pre- and post-treatment values of patients treated with monoblock and twin-block appliances with the values of the skeletal Class I individuals.

Material and Methods

The initial lateral cephalometric radiographs of the pubertal untreated skeletal class I patients and cephalometric radiographs of 60 (30 monoblock, 30 twin-block) patients before and after the functional treatment were included in the study. Skeletal, dental, and soft tissue measurements were performed by a single researcher using Dolphin Imaging software version 11.95 (Dolphin Imaging, Chatsworth, CA, USA). Paired t-test was used for statistical evaluation and P < 0.05 was considered statistically significant.

Results

In both monoblock and twin-block groups, there was a statistically significant increase in the measurements of the lower jaw and the vertical direction values (sella nasion B point (SNB), pogonion nasion perpendicular, Y-axis, sella nasion-gonion gnathion, palatal-mandibular angle, anterior facial height, mandibular length P < 0.05); however, in the Twin-block group, the lower jaw was found to be displaced more forward (change for twin-block; SNB = 2.35, Wits appraisal = -4.77). The most measurements of the twin-block treated group were similar to the control group.

Conclusions

Both functional appliances have been identified to be useful in achieving treatment targets; however, with twin-block, results closer to ideal values are obtained.

Opening up on airways: the purported effect of nasorespiratory obstruction on dentofacial growth

Nasorespiratory obstruction has been purported to influence dentofacial growth adversely. This has sparked considerable debate for decades with a resurgence in interest in 'airway friendly orthodontics' among both general and specialist dental practitioners. This critical review aims to evaluate the current literature relating to two questions: does nasorespiratory obstruction alter dentofacial growth, and does early intervention targeted at alleviating nasorespiratory obstruction improve dentofacial growth? The strength of association between nasorespiratory obstruction, mouth breathing and a long face is weak. The common methodological flaws in research include unblinded and cross-sectional study designs, a lack of adequate controls, inadequate follow-up, subjective assessments and inadequate statistical power. Vertical dentofacial growth has a strong genetic influence, which implies a relatively minor contribution of environmental factors including airway obstruction. The current evidence does not support recommending procedures, such as adenotonsillectomy and maxillary expansion, with the singular aim of negating a hyperdivergent (vertical) dentofacial growth pattern. In light of low-quality evidence, both the World Health Organization guidelines and ethical principles dictate that greater emphasis is placed on avoiding harm and wastage of resources over alternative options. These findings call for quality improvement in undergraduate and postgraduate curricula and continuing professional development for health professionals.

Parathyroid Hormone Gene and Genes Involved in the Maintenance of Vitamin D Levels Association with Mandibular Retrognathism

In this study we evaluated whether single nucleotide polymorphisms (SNPs) in the genes encoding PTH, VDR, CYP24A1, and CYP27B1 were associated with mandibular retrognathism (MR). Samples from biologically-unrelated Brazilian patients receiving orthodontic treatment were included in this study. Pre-orthodontic lateral cephalograms were used to determine the phenotype. Patients with a retrognathic mandible were selected as cases and those with an orthognathic mandible were selected as controls. Genomic DNA was used for genotyping analysis of SNPs in PTH (rs694, rs6256, and rs307247), VDR (rs7975232), CYP24A1 (rs464653), and CYP27B1 (rs927650). Chi-squared or Fisher’s tests were used to compare genotype and allele distribution among groups. Haplotype analysis was performed for the SNPs in PTH. The established alpha was p < 0.05. Multifactor dimensionality reduction (MDR) was used to identify SNP–SNP interactions. A total of 48 (22 males and 26 females) MR and 43 (17 males and 26 females) controls were included. The linear mandibular and the angular measurements were statistically different between MR and controls (p < 0.05). In the genotype and allele distribution analysis, the SNPs rs694, rs307247, and rs464653 were associated with MR (p < 0.05). MDR analyses predicted the best interaction model for MR was rs694–rs927650, followed by rs307247–rs464653–rs927650. Some haplotypes in the PTH gene presented statistical significance. Our results suggest that SNPs in PTH, VDR, CYP24A1, and CYP27B1 genes are associated with the presence of mandibular retrognathism.

Genetics of Dentofacial and Orthodontic Abnormalities

The development of craniofacial complex and dental structures is a complex and delicate process guided by specific genetic mechanisms. Genetic and environmental factors can influence the execution of these mechanisms and result in abnormalities. An insight into the mechanisms and genes involved in the development of orofacial and dental structures has gradually gained by pedigree analysis of families and twin studies as well as experimental studies on vertebrate models. The development of novel treatment techniques depends on in-depth knowledge of the various molecular or cellular processes and genes involved in the development of the orofacial complex. This review article focuses on the role of genes in the development of nonsyndromic orofacial, dentofacial variations, malocclusions, excluding cleft lip palate, and the advancements in the field of molecular genetics and its application to obtain better treatment outcomes.

Orthodontic treatment of a disto-occlusion with and favorable growth pattern

The variety of etiological factors contributing to the development of distal bite various form, as well as the structures that are affected by the disorders determine the deegre of complexity of the malocclusion itself, and thus the choice of therapeutic procedure by which it will be treated. An 11-year-old female patient was diagnosed with this type of malocclusion with a certain degree of presence of other irregularities. After a detailed diagnostic procedure, and determining the type of growth, we approach the therapeutic procedure in two phases. By applying the funcional therapy in the first phase, we correct the vertical growth type, and then in the second phase of therapy using a fixed technique we achieve harmonious intermaxillary relations, an adequate molar and canine Class I relationship as well, thus improving the aesthetics of the patient's face.

Stability of single-jaw vs two-jaw surgery following the correction of skeletal class III malocclusion: A systematic review and meta-analysis

This review aims to compare the stability of sagittal skeletal and overjet anteroposterior correction of skeletal class III malocclusion in single-jaw and two-jaw orthognathic procedures. An unrestricted comprehensive electronic search was undertaken on Embase, Cochrane's CENTRAL, Web of Science, Medline, Scopus and LILACs databases up to October 2020. The bibliographies of relevant studies, ongoing, unpublished and grey literature were screened. Two independent reviewers performed study selection, bias assessment and data extraction; a third reviewer mediated inconsistencies. Randomized clinical trials, prospective cohort, retrospective cohort and series with a minimum of 1 year follow-up were eligible for inclusion. Additional subgroup analyses were undertaken. The generated effects were scored using the GRADE approach. Nine articles met the inclusion criteria and eight studies were subsequently analysed quantitatively. No significant difference in sagittal stability at the ANB angle, A-point or B-point on a short-term was detected. However, a statistically significant difference, indicating a greater short-term relapse in overjet with mandibular setbacks alone, was found (MD: -0.40 mm; 95% CI -0.77 to -0.04; I² : 0%; P = .03). Long-term follow-up (≥5 years) revealed a statistically non-significant difference in stability of sagittal skeletal and overjet corrections. Within the limitations of this review, both procedures seem to offer comparable skeletal and overjet stability outcomes; however, further high-quality research is required to confirm these findings.

The Characteristics of Adjacent Anatomy of Mandibular Third Molar Germs: A CBCT Pilot Study in Patients with Osteogenesis Imperfecta

(1) Objectives: The aim of our study was to investigate the anatomical features of lower third molar and its adjacent anatomical connections in type I Osteogenesis Imperfecta (OI) patients through cone beam computed tomography (cbct). (2) Methods: The study was conducted among 25 patients, 13 patients with type I OI and 12 control patients (individuals with no disorders and no treatment); average age was 15.44 ± 2.06, 23 third molar germs for each group. The germs have been compared to the parameters using the Mann-Whitney test. A chi-square test was also used to investigate the correlation between the status case/control and tooth development stage. (3) Results: Mann-Whitney test showed significant differences between cases and controls: diameter of the tooth germ in toto (U = 93.5; p < 0.001), tooth development stage, (U = 145; p < 0.01), roots length (U = 44.5; p < 0.01), cementoenamel junction diameter (U = 157.5; p < 0.05), size of the pulp chamber (U = 95.5; p < 0.05). Type I OI is not associated with the relationship between the germ of mandibular third molar and alveolar canal on axial plane (χ² = 4.095; p = 0.129), and parasagittal (χ² = 4.800; p = 0.091). The association between type I OI and relationship with the germ of mandibular third molar and alveolar canal on the coronal plane has been significant (χ² = 9.778; p < 0.05) as the perforation of the lingual cortical bone in the region of mandibular third molar tooth germ (χ² = 11.189; p < 0.01). (4) Conclusions: The results confirm the cbct accuracy in the evaluation of bone density in type I OI patients giving also the opportunity to study the tridimensional anatomy of germs and the adjacent anatomical structures in order to avoid any perioperative complications.

The Jaw Epidemic: Recognition, Origins, Cures, and Prevention

Contemporary humans are living very different lives from those of their ancestors, and some of the changes have had serious consequences for health. Multiple chronic "diseases of civilization," such as cardiovascular problems, cancers, ADHD, and dementias are prevalent, increasing morbidity rates. Stress, including the disruption of traditional sleep patterns by modern lifestyles, plays a prominent role in the etiology of these diseases, including obstructive sleep apnea. Surprisingly, jaw shrinkage since the agricultural revolution, leading to an epidemic of crooked teeth, a lack of adequate space for the last molars (wisdom teeth), and constricted airways, is a major cause of sleep-related stress. Despite claims that the cause of this jaw epidemic is somehow genetic, the speed with which human jaws have changed, especially in the last few centuries, is much too fast to be evolutionary. Correlation in time and space strongly suggests the symptoms are phenotypic responses to a vast natural experiment-rapid and dramatic modifications of human physical and cultural environments. The agricultural and industrial revolutions have produced smaller jaws and less-toned muscles of the face and oropharynx, which contribute to the serious health problems mentioned above. The mechanism of change, research and clinical trials suggest, lies in orofacial posture, the way people now hold their jaws when not voluntarily moving them in speaking or eating and especially when sleeping. The critical resting oral posture has been disrupted in societies no longer hunting and gathering. Virtually all aspects of how modern people function and rest are radically different from those of our ancestors. We also briefly discuss treatment of jaw symptoms and possible clinical cures for individuals, as well as changes in society that might lead to better care and, ultimately, prevention.

Influence of heritability on occlusal traits: a systematic review of studies in twins

BACKGROUND

The aim of this systematic review was to identify, evaluate, and provide a current literature about the influence of heritability on the determination of occlusal traits.

MATERIALS AND METHODS

MEDLINE, SCOPUS, Web of Science, LILACS, and Google Scholar were searched without restrictions up to March 2020. Studies with twin method were considered and the risk of bias assessment was performed using quality of genetic association studies checklist (Q-Genie). The coefficient of heritability (h²), model-fitting approaches, and coefficient correlation were used to estimate the genetic/environmental influence on occlusal traits. The GRADE tool was used to assess the quality of the evidence.

RESULTS

Ten studies met the eligibility criteria. Three studies presented good quality, five moderate quality, and two poor quality. Most studies have found that the intra-arch traits, mainly the maxillary arch morphology, such as width (h² 16-100%), length (h² 42-100%), and shape (h² 42-90%), and the crowding, mainly for mandibular arch (h² 35-81%), are under potential heritability influence. The traits concerning the inter-arch relationship, as overjet, overbite, posterior crossbite, and sagittal molar relation, seem not to be genetically determined. The certainty of the evidence was graded as low for all outcomes.

CONCLUSIONS

Although weak, the available evidence show that the heritability factors are determinant for the intra-arch traits, namely, arch morphology and crowding. Possibly due they are functionally related, the occlusal traits concerning the maxillary and mandibular relationship seem to have environmental factors as determinants. In this scenario, early preventive approaches can offer a more effective and efficient orthodontic treatment.

Non-surgical interdisciplinary management for an adult patient with a Class III malocclusion

Non-surgical camouflage orthodontic treatment can be effective for the management of carefully selected patients with mild to moderate Class III malocclusion. This case report demonstrates how a synergistic combination of camouflage orthodontic treatment and appropriate adjunctive restorative procedures can provide a pleasing treatment outcome for a patient with a significant skeletal Class III malocclusion and diminutive maxillary lateral incisors.

Ectopic eruption of the second premolar: an analysis of four different treatment approaches

PURPOSE

Ectopic second premolars may lead to impaction and loss of space in the jaws, and in rare cases even to resorption of the first permanent molar. The aim of this study was to analyse different treatment strategies of ectopic second premolars and if possible give guidelines on when to favour different treatment approaches.

MATERIALS AND METHODS

The study was a retrospective, non-randomised, outcome analysis of treatment on 41 ectopic second premolars in 37 patients (24 females and 13 males). In all cases oral examination, radiographs (pre-, peri-, and post) and full medical history were obtained. The treatment options included: (a) spontaneous eruption, (b) spontaneous eruption + extraction of primary tooth, (c) surgical exposure, (d) surgical uprighting, and (e) surgical uprighting + orthodontic extrusion. For evaluation each tooth was scored according to: (1) stage of root development, (2) distance between edges of the premolar and first permanent molar, (3) depth of impaction, (4) inclination, (5) horizontal position of the tooth. The level of significance was set to 5%.

RESULTS

Only mild cases of ectopic second premolars are self-correcting. Based on the position of the tooth in the jaw different treatment options may be chosen, these may include: extraction of primary predecessor (impaction depth < 5 mm, inclination < 55°), surgical exposure of tooth germ (impaction depth < 5.5 mm, inclination < 95°) or surgical uprighting (impaction depth > 5.5 mm with no inclination limit).

CONCLUSION

If there is no sign of self-correction after a short observation period, it is important to consider active treatment to help guiding the tooth into the correct eruption pathway.

Ectopic maxillary third molar in Early Pleistocene Homo antecessor from Atapuerca-Gran Dolina site (Burgos, Spain)

OBJECTIVES

Here we describe the case of an ectopic maxillary third molar (M³ ), preventing the eruption of the M² , in the individual H3 of the hominin hypodigm of level TD6.2 of the Early Pleistocene site of Gran Dolina (Sierra de Atapuerca, Spain).

MATERIALS AND METHODS

The fossil remains from the TD6.2 level of the Gran Dolina site (about 170 specimens) are assigned to Homo antecessor. Different geochronological methods place these hominins in the oxygen isotopic stage 21, between 0.8 and 0.85 million years ago (Ma). The immature individual H3 is represented by an almost complete midface (ATD6-69), preserving various teeth in situ. We used high-resolution microtomograhy (mCT) to investigate the abnormal position of the left M³ , virtually reconstruct M² , and M³ as well as assessing the development stage of these. Finally, we compare this case with extinct and extant populations.

RESULTS

Based on the identified signs, we suggest that individual H3 suffered from a unilateral impaction of the M² as a result of the ectopic position of the developing M³ .

DISCUSSION

We conclude that the most likely etiology for the ectopic position of the M³ is the lack of space in the maxilla. We discuss possible contributing factors, such as morphometric aspects of the maxilla and the early mineralization of the M³ , to support the M² impaction. Finally, due to the early age at death of this individual we did not identify any secondary lesion associated with the M² impaction.

Vertical growth in mono-and dizygotic twins: A longitudinal cephalometric cohort study

OBJECTIVE

The aims of this longitudinal analysis of untreated monozygotic and dizygotic twins were to investigate vertical changes of the craniofacial structures during growth, to determine the concordance between genetically twins and to assess the genetic component for the various aspects of vertical growth.

SETTINGS AND SAMPLE POPULATION

The sample consisted of 34 pairs of untreated monozygotic twins (23 male, 11 female) and 30 untreated dizygotic siblings of multiple birth (8 male, 8 female and 14 mixed) from the Forsyth Moorrees Twin Study (1959-1975); lateral cephalograms taken from 6 to 18 years of age were analysed at 3-year intervals.

MATERIALS AND METHODS

Cephalograms were traced, and longitudinal changes between twins in six angular and proportional vertical cephalometric variables (SN-NL, ML-NL, SN-ML, y-axis, PFH/AFH and LAFH/AFH) were analysed with intraclass correlation coefficients and linear regression modelling.

RESULTS

The concordance between monozygotic/dizygotic twins at 18 years of age was moderate to high with intraclass correlation coefficient values between 0.51 and 0.66. Additionally, sex differences in concordance at 18 years of age were found for three variables. High heritability (66%-79%) was observed for 5 of the 6 variables (LAFH/AFH, ML-NL, y-axis, SN-ML, PFH/AFH), while SN-NL showed limited heritability (34%).

CONCLUSIONS

Although monozygotic/dizygotic twins share at least part of their genetic material, differences in the vertical dimension were found. This supports the complex developmental mechanism of the human face and the varying influence of genetic and environmental factors.

The effects of playing wind musical instruments on the occlusal characteristics in a Northern Nigerian Population

Introduction

Dentists are often questioned on whether playing a wind musical instrument can adversely affect dental occlusion. This study compared the occlusal characteristics in wind instrument players (WIPs) and non-WIPs.

Materials and Methods

This was a cross-sectional comparative study comprising a group of fifty males aged 18-45 years that had been playing wind instruments for a minimum of 2 years, whereas the control group were non-WIPs in the same environment. All the participants had full complement of dentition. The occlusal characteristics of overjet, overbite, anterior open bite and Little's irregularity were assessed for both groups. Excellent intra-examiner reliability was observed (Cronbach's alpha - 0.997). The Statistical Package for Social Sciences (SPSS Inc., Chicago, IL, USA) version 17 was used for data analysis, and statistical significance level was set at P < 0.05.

Results

The number of years of playing wind musical instrument ranged from 2 to 25 years. The mean overjet was 3.46 ± 1.49 mm and 3.18 ± 1.27 mm in the WIP and non-WIP groups, respectively (P > 0.05). The maxillary anterior segment showed statistically significantly higher Little's Irregularity Index score in the WIP group (3.18 ± 3.73 mm) than that in the non-WIP group (1.87 ± 2.21 mm) (P < 0.05). The maxillary Little's Irregularity Index score in trumpet and trombone players (3.55 ± 3.93 mm) was significantly higher than that in saxophone and clarinet players (1.69 ± 2.39 mm). Both the maxillary and mandibular anterior-segment alignments were neither influenced by the number of years nor the frequency of play.

Conclusions

Playing wind musical instruments significantly affects the maxillary anterior-segment alignment.

The role of accelerated dental development on the occurrence of aberrant dental traits that indicate malocclusion

BACKGROUND

Timing of dental development might help orthodontists to optimize initiation of treatment and to prevent and intercept dental misalignment. This study examines the association between timing of dental development and aberrant dental traits such as crowding, impaction, and hypodontia.

METHODS

This study was performed using 4446 ten-year-old children from a multiethnic birth cohort, the Generation R Study. Dental development was defined using the Demirjian method. Crowding, impaction, and hypodontia were ascertained from 2D and 3D pictures and radiographs. We built three series of logistic regression models to test the associations of dental age with crowding, impaction, and hypodontia. Similar models were built to investigate the associations of the developmental stages of each left mandibular tooth with crowding, impaction, and hypodontia.

RESULTS

Inverse associations were found between every 1-year increase in dental age and the presence of crowding [odds ratio (OR) = 0.84, 95% confidence interval (CI): 0.79, 0.89], impaction of teeth (OR = 0.66, 95% CI: 0.52, 0.84), and hypodontia (OR = 0.52, 95% CI: 0.47, 0.56). Lower developmental stages of the second premolar were associated with the presence of crowding (OR = 0.90, 95% CI: 0.83, 0.98). Lower developmental stages of the second premolar (OR = 0.88, 95% CI: 0.79, 0.98), first molar (OR = 0.76, 95% CI: 0.65, 0.90), and the second molar (OR = 0.83, 95% CI: 0.73, 0.94) were associated with the presence of tooth impaction. Lower developmental stages of all mandibular teeth except the central incisor were associated with hypodontia (P < 0.05).

CONCLUSION

Accelerated dental development is associated with lower occurrence of crowding, impaction, and hypodontia.

Heritability of teeth angulation and inclination in patients with overt malocclusion

PURPOSE

To use 3-dimensional cone beam computed tomography (CBCT) images obtained on patients before treatment with dental malocclusion to calculate the heritability estimates of full-tooth angulation and inclination. A heritability estimate is a number between zero and one indicating the percentage of genetic factors involved in determining the phenotypic variation observed.

METHOD

CBCT images of 111 patients (51 sibships) were analysed measuring both tooth angulation and inclination using the Anatomage Invivo5 software for central incisor to second molar. The long axis of each tooth was defined and traced as the cusp tip of the most mesiobuccal cusp to 6mm coronal to the apex of the mesiobuccal root. SPSS statistical software was used to analyse the data and calculate the heritability estimates for each tooth type in the maxilla and in the mandible regardless of the side.

RESULTS

Teeth inclination showed higher heritability estimates than tooth angulation. Furthermore, maxillary teeth showed higher heritability estimates than mandibular teeth and anterior teeth showed higher heritability than posterior teeth.

CONCLUSION

Genetic effect was more evident on tooth inclination than tooth angulation, on anterior teeth more than posterior teeth, and on maxillary teeth more than mandibular teeth.

Orthodontic Treatment Need and the Psychosocial Impact of Malocclusion in 12-Year-Old Hong Kong Children

Objectives

To determine the prevalence of orthodontic treatment need in 12-year-old children in Hong Kong and its relationship with the psychosocial impact of malocclusion and to assess their associations with sociodemographic factors.

Materials and Methods

A random sample of 687 12-year-old children was recruited from 45 secondary schools in Hong Kong. Orthodontic treatment need was assessed on study models by five indices: the Dental Health Component of the Index of Orthodontic Treatment Need (IOTN-DHC), the Aesthetic Component of the IOTN (IOTN-AC), the Dental Aesthetic Index (DAI), the Index of Complexity Outcome and Need (ICON), and the Peer Assessment Rating (PAR). The psychosocial impact of malocclusion on participants and sociodemographic factors were obtained from a questionnaire. Logistic regression was used to examine the correlations between treatment need and the psychosocial impact of malocclusion as well as their associations with sociodemographic factors.

Results

The final number of participants was 667 (339 boys and 328 girls, participation rate 667/687 = 97.1%). The prevalence of orthodontic treatment need varied depending on the indices used (10.9–47.8%), but significant correlations were found among the five indices (p < 0.01). The uptake of treatment among the cohort was 2.3%. Boys had higher IOTN-DHC (p < 0.05), DAI (p < 0.05), and PAR (p = 0.05) scores than girls. IOTN-AC was significantly associated with the psychosocial impact of malocclusion (p < 0.05). Parents' level of education and household income were not significantly associated with either treatment need or the psychosocial impact of malocclusion (p > 0.05).

Conclusion

The need for orthodontic treatment in 12-year-old children in Hong Kong remained high, and the uptake of treatment was low. Boys had a higher normative treatment need than girls. Among the five indices, IOTN-AC appears to be the best indicator of the psychosocial impact of malocclusion.

Three-dimensional palatal anatomic characteristics' correlation with dermatoglyphic heterogeneity in Angle malocclusions

OBJECTIVES

To assess correlation of dermatoglyphic (DG) pattern with quantitative palatal anatomic parameters measured using three-dimensional (3D) scanning of dental casts and to explore the possibility of utilizing these to predict future occurrence of malocclusion.

MATERIALS AND METHODS

Pretreatment casts of 477 Saudi Arabian patients were divided into Class I, II, and III malocclusion groups. Fingerprints were recorded for all hand digits using a digital biometric device. Maxillary arch analysis was accomplished including intercanine, intermolar distance, palatal height, and palatal area. The results were statistically analyzed.

RESULTS

The mean surface area of the palate was highest in Class II malocclusion. The DG pattern was not significantly associated with the type of malocclusion, except in the instance of the double loop characteristic (P = .05). There was a strong correlation, however, between DG characteristics like simple arch, loop, and double loop and palatal dimensions (intercanine, intermolar distance, and palatal height). Heterogeneity of DG pattern could be reliably used to predict palatal dimensions. Logistic regression revealed that only tented arch, symmetrical, spiral DG patterns and palatal area were significant but weak predictors of Angle malocclusion (P < .05).

CONCLUSIONS

A novel correlation of DG pattern with 3D palatal anatomic characteristics was assessed in different Angle malocclusion classes. Few of the DG characteristics and palatal dimensions showed significant correlations. However, only some of these were significant predictors of Angle malocclusion.

Determination of TNF-a Gene Polymorphisms on Skeletal Pattern in Class II Malocclusion

Abstract Bone development and growth is a non-going, life-long process, varying greatly among individuals and much of this variation could be modulated by genetic factors. The purpose of this study was to evaluate the association between the polymorphisms in the TNF-a gene and skeletal class II malocclusion. Single nucleotide polymorphisms in TNF-a (rs1799724; rs1800629) gene were studied in 79 skeletal class II malocclusion and 102 skeletal class I malocclusion subjects from Straight Wire Group of Studies on Orthodontics and Functional Orthopedics for Maxillary from Rio de Janeiro, Brazil. The Genotyping of these selected polymorphisms was carried out by TaqMan real-time PCR using genomic DNA extracted from buccal cells. All allele and genotype frequencies were compared between the groups using the PLINK® software in a free, in a dominant and in a recessive model using a chi-square test (p≤0.05). There was no significant association of TNF-a (rs1799724; rs1800629) genotype and allele distribution with skeletal class II malocclusion. Regardless of the dominant or recessive genetic model, the preferential genotype associations for rs1799724 and rs1800629 was insignificant. In conclusion, no evidence of association is apparent between genetic polymorphisms involving TNF-a and skeletal class II malocclusion or the position of the maxilla and mandible in the postero-anterior direction.

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.

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.

Relationship between matrilin-1 gene polymorphisms and mandibular retrognathism

INTRODUCTION

Mandibular retrognathism is a type of malocclusion that refers to an abnormal posterior position of the mandible as a result of a developmental abnormality. From the literature, it is evident that the mandibular growth pattern is determined by the intramembranous ossification of the mandibular body and endochondral ossification of the condyle. Matrilin-1 is a cartilage extracellular matrix protein, and matrilin-1 gene (MATN1) polymorphisms have been found to be involved in dental malocclusions of humans. In this study, we aimed to examine the association between MATN1 polymorphisms and the risk of mandibular retrognathism, in a case-control study with a South Indian population.

METHODS

Eighty-one patients with mandibular retrognathism (SNB, <78°) and 71 controls having an orthognathic mandible (SNB, 80° ± 2°) were recruited. In both the patient and control groups, subjects with an orthognathic maxilla (SNA, 82° ± 2°) were included. Three single nucleotide polymorphisms of the MATN1 gene (rs1149048, rs1149042, and rs1065755) were genotyped using polymerase chain reaction-restriction fragment length polymorphism. The statistical association analysis was performed using the chi-square test. Pair-wise linkage disequilibrium was computed, and haplotypes were compared between subjects and controls. Nonparametric tests were used to compare cephalometric measurements between groups.

RESULTS

No polymorphic site deviated from Hardy-Weinberg equilibrium in the controls. The rs1149042 genotypes and alleles were found to be associated with reduced risk of mandibular retrognathism. Furthermore, rs1149042 genotypes were associated with mandibular measurements (SNB and ANB). There was no strong and consistent linkage disequilibrium linkage disequilibrium across two different single nucleotide polymorphisms and haplotypes were not associated with mandibular retrognathism.

CONCLUSIONS

The results of our study suggest an association between the MATN1 gene polymorphisms and mandibular retrognathism.

Orthodontic treatment for deep bite and retroclined upper front teeth in children

BACKGROUND

A Class II division 2 malocclusion is characterised by upper front teeth that are retroclined (tilted toward the roof of the mouth) and an increased overbite (deep overbite), which can cause oral problems and may affect appearance.This problem can be corrected by the use of special dental braces (functional appliances) that move the upper front teeth forward and change the growth of the upper or lower jaws, or both. Most types of functional appliances are removable and this treatment approach does not usually require extraction of any permanent teeth. Additional treatment with fixed braces may be necessary to ensure the best result.An alternative approach is to provide space for the correction of the front teeth by moving the molar teeth backwards. This is done by applying a force to the teeth from the back of the head using a head brace (headgear) and transmitting this force to part of a fixed or removable dental brace that is attached to the back teeth. The treatment may be carried out with or without extraction of permanent teeth.If headgear use is not feasible, the back teeth may be held in place by bands connected to a fixed bar placed across the roof of the mouth or in contact with the front of the roof of the mouth. This treatment usually requires two permanent teeth to be taken out from the middle of the upper arch (one on each side).

OBJECTIVES

To establish whether orthodontic treatment that does not involve extraction of permanent teeth produces a result that is any different from no orthodontic treatment or orthodontic treatment involving extraction of permanent teeth, in children with a Class II division 2 malocclusion.

SEARCH METHODS

Cochrane Oral Health's Information Specialist searched the following electronic databases: Cochrane Oral Health's Trials Register (to 13 November 2017), the Cochrane Central Register of Controlled Trials (CENTRAL) (the Cochrane Library, 2017, Issue 10), MEDLINE Ovid (1946 to 13 November 2017), and Embase Ovid (1980 to 13 November 2017). To identify any unpublished or ongoing trials, the US National Institutes of Health Ongoing Trials Register (ClinicalTrials.gov) and the World Health Organization International Clinical Trials Registry Platform (apps.who.int/trialsearch) were searched. We also contacted international researchers who were likely to be involved in any Class II division 2 clinical trials.

SELECTION CRITERIA

Randomised controlled trials (RCTs) and controlled clinical trials (CCTs) of orthodontic treatments to correct deep bite and retroclined upper front teeth in children.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened the search results to find eligible studies, and would have extracted data and assessed the risk of bias from any included trials. We had planned to use random-effects meta-analysis; to express effect estimates as mean differences for continuous outcomes and risk ratios for dichotomous outcomes, with 95% confidence intervals; and to investigate any clinical or methodological heterogeneity.

MAIN RESULTS

We did not identify any RCTs or CCTs that assessed the treatment of Class II division 2 malocclusion in children.

AUTHORS' CONCLUSIONS

There is no evidence from clinical trials to recommend or discourage any type of orthodontic treatment to correct Class II division 2 malocclusion in children. This situation seems unlikely to change as trials to evaluate the best management of Class II division 2 malocclusion are challenging to design and conduct due to low prevalence, difficulties with recruitment and ethical issues with randomisation.

Orthodontic treatment for deep bite and retroclined upper front teeth in children

BACKGROUND

A Class II division 2 malocclusion is characterised by upper front teeth that are retroclined (tilted toward the roof of the mouth) and an increased overbite (deep overbite), which can cause oral problems and may affect appearance.This problem can be corrected by the use of special dental braces (functional appliances) that move the upper front teeth forward and change the growth of the upper or lower jaws, or both. Most types of functional appliances braces are removeable and this treatment approach does not usually require extraction of any permanent teeth. Additional treatment with fixed braces may be necessary to ensure the best result.An alternative approach is to provide space for the correction of the front teeth by moving the molar teeth backwards. This is done by applying a force to the teeth from the back of the head using a head brace (headgear) and transmitting this force to part of a fixed or removable dental brace that is attached to the back teeth. The treatment may be carried out with or without extraction of permanent teeth.If headgear use is not feasible, the back teeth may be held in place by bands connected to a fixed bar placed across the roof of the mouth or in contact with the front of the roof of the mouth. This treatment usually requires two permanent teeth to be taken out (one on each side).

OBJECTIVES

To establish whether orthodontic treatment that does not involve extraction of permanent teeth produces a result that is any different from no orthodontic treatment or orthodontic treatment involving extraction of permanent teeth, in children with a Class II division 2 malocclusion.

SEARCH METHODS

Cochrane Oral Health's Information Specialist searched the following electronic databases: Cochrane Oral Health's Trials Register (to 10 January 2017), the Cochrane Central Register of Controlled Trials (CENTRAL) (the Cochrane Library, 2016, Issue 11), MEDLINE Ovid (1946 to 10 January 2017), and Embase Ovid (1980 to 10 January 2017). To identify any unpublished or ongoing trials, the US National Institutes of Health Ongoing Trials Register (ClinicalTrials.gov) and the World Health Organization International Clinical Trials Registry Platform (apps.who.int/trialsearch) were searched. We also contacted international researchers who were likely to be involved in any Class II division 2 clinical trials.

SELECTION CRITERIA

Randomised controlled trials (RCTs) and controlled clinical trials (CCTs) of orthodontic treatments to correct deep bite and retroclined upper front teeth in children.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened the search results to find eligible studies, and would have extracted data and assessed the risk of bias from any included trials. We had planned to use random-effects meta-analysis; to express effect estimates as mean differences for continuous outcomes and risk ratios for dichotomous outcomes, with 95% confidence intervals; and to investigate any clinical or methodological heterogeneity.

MAIN RESULTS

We did not identify any RCTs or CCTs that assessed the treatment of Class II division 2 malocclusion in children.

AUTHORS' CONCLUSIONS

It is not possible to provide any evidence-based guidance to recommend or discourage any type of orthodontic treatment to correct Class II division 2 malocclusion in children. Trials should be conducted to evaluate the best management of Class II division 2 malocclusion.

Growth and Development of Dentofacial Complex influenced by Genetic and Environmental Factors using Monozygotic Twins

AIM

The purpose of this study was to determine the possible effects of genetic and environmental factors on dentofacial complex using monozygotic twins.

MATERIALS AND METHODS

The study sample was made of 21 pairs of monozygotic twins (14 female pairs and seven male pairs) between 10 and 25 years. Pretreatment lateral cephalo-grams were used which were traced and digitized, and various landmarks to determine the anteroposterior and vertical proportions were marked. Samples were divided into two groups. The correlation between groups was found by calculating Pearson's product moment correlation coefficients.

RESULTS

The range of the correlation coefficient was from 0.705 to 0.952. Gonial angle showed the highest correlation coefficient (0.952), while saddle angle showed the lowest correlation coefficient (0.705).

CONCLUSION

The growth and development of craniofacial complex is under mutifactorial control. However, genetic influences do tend to play a dominant role.

CLINICAL SIGNIFICANCE

By studying identical twins, we can study about the interaction of the environment with the genes and how it affects the growth and development of the body in general and dentofacial complex in particular. By utilizing twin studies, we can identify whether a particular trait, disease, or disorder is influenced more strongly by genetics or by the environment. Success of orthodontic treatment depends on a proper diagnosis of the problem including its etiological factors. Genetic studies let the orthodontists to understand the effects of genetic and environmental factors in the growth and development of dentofacial complex better and allows to prevent or treat malocclusions and skeletal anomalies in better ways.

Dental and Temporomandibular Joint Pathology of the North American Brown Bear (Ursus arctos horribilis, Ursus arctos middendorffi and Ursus arctos sitkensis)

Museum specimens (maxillae and mandibles) from 393 North American brown bears (Ursus arctos) from Alaska were examined macroscopically according to predefined criteria and 204 specimens were included in this study. The specimens were acquired between 1905 and 2012. There were 99 specimens (48.5%) from male animals, 87 (42.7%) from female animals and 18 (8.8%) from animals of unknown sex. The ages of the animals ranged from neonate to adult, with 92 adults (45.1%) and 112 young adults (54.9%) included and neonates/juveniles excluded from the study. The number of teeth available for examination was 6,525 (76.2%); 8.6% of teeth were absent artefactually, 0.8% were deemed absent due to acquired tooth loss and 14.5% were absent congenitally. None of the brown bears had supernumerary teeth, persistent deciduous teeth or abnormally formed crowns. Only four of the specimens in the present population were affected by enamel hypoplasia and one specimen contained two mandibular fourth premolar teeth with one root instead of two. All 204 specimens displayed at least some degree of attrition/abrasion, affecting 63% of all teeth, ranging from mild wear of the enamel to deep abrasion associated with pulp exposure. Ten-times more adult than young adult specimens had abrasion causing pulp exposure, while more young adults showed mild attrition/abrasion. Dental fractures were noted in one-third of brown bears and in 3.0% of the total number of present teeth. More adult brown bears had dental fractures than young adults. There were 11 specimens (5.4%) that displayed overt periapical disease, affecting a total of 20 dental alveoli (0.22%), with adults significantly more affected than young adults. Some degree of periodontitis was seen in 145 specimens (71.1%), affecting 13.6% of all dental alveoli. Nearly one-third (29.9%) of skulls displayed skeletal and/or dental malocclusion, most commonly a level bite. Lesions consistent with temporomandibular joint (TMJ) osteoarthritis were found in 27 specimens (13.2%). Caries lesions were discovered in four specimens (2.0%), affecting eight teeth in total. Although the clinical significance of dental and TMJ pathology in the brown bear remains elusive, the occurrence and severity of some of these lesions may play an important role in the morbidity of this species.

An Assessment of Correlation between Dermatoglyphic Patterns and Sagittal Skeletal Discrepancies

INTRODUCTION

Investigators over years have been fascinated by dermatoglyphic patterns which has led to the development of dermatoglyphics as a science with numerous applications in various fields other than being the best and most widely used method for personal identification.

AIM

To assess the correlation between dermatoglyphic patterns and sagittal skeletal discrepancies.

MATERIALS AND METHODS

A total of 180 patients, aged 18-40 years, were selected from those who attended the outpatient clinic of the Deparment of Orthodontics and Dentofacial Orthopedics, Mar Baselios Dental College, Kothamangalam, Kerala, India. The fingerprints of both hands were taken by ink and stamp method after proper hand washing. The patterns of arches, loops and whorls in fingerprints were assessed. The total ridge count was also evaluated. Data was also sent to the fingerprint experts for expert evaluation. The sagittal jaw relation was determined from the patient's lateral cephalogram. The collected data was then statistically analyzed using Chi-square tests, ANOVA and Post-hoc tests and a Multinomial regression prediction was also done.

RESULTS

A significant association was observed between the dermatoglyphic pattern exhibited by eight fingers and the sagittal skeletal discrepancies (p<0.05). An increased distribution of whorl pattern was observed in the skeletal Class II with maxillary excess group and skeletal Class II with mandibular deficiency group while an increased distribution of loop pattern was seen in the skeletal Class III with mandibular excess group and skeletal Class III with maxillary deficiency group. Higher mean of total ridge count was also seen in the groups of skeletal Class II with maxillary excess and skeletal Class II with mandibular deficiency. Multinomial regression predicting skeletal pattern with respect to the fingerprint pattern showed that the left thumb impression fits the best model for predicting the skeletal pattern.

CONCLUSION

There was a significant association between dermatoglyphic patterns and sagittal skeletal discrepancies. Dermatoglyphics could serve as a cost effective screening tool of these craniofacial problems.