Genetic factors contributing to skeletal class III malocclusion: a systematic review and meta-analysis

Prevalence of Malocclusion Traits in Primary Dentition, 2010-2024: A Systematic Review

The present review was aimed to describe the prevalence and the regional distribution of malocclusion among preschool children worldwide. Two independent reviewers performed a systematic literature search to identify English publications from January 2010 to May 2024 using PubMed, ISI Web of Science and Embase. Search MeSH key words were "malocclusion", "primary dentition" and "child, preschool". The reporting quality was assessed by the modified Newcastle-Ottawa Quality Assessment Scale. We identified 2599 publications and recruited 47 articles. Fourteen of the included studies were conducted in Asia, four in Europe, twenty-eight in South America and one in Africa. The prevalence of malocclusion ranged from 28.4% to 83.9%, and half of the reported prevalences were higher than 50%. The highest percentage was in Asia (61.81%), followed by Europe (61.50%), South America (52.69%) and Africa (32.50%). Statistically significant differences existed in deep overbite, anterior open bite, posterior crossbite, edge-to-edge incisor relationship and distal step between continents (p < 0.05). Europe showed the highest prevalence (33.08%) of deep overbite. Africa showed the highest prevalence (18.60%) of anterior open bite. Europe showed the highest prevalence (15.38%) of posterior crossbite. The most common malocclusion traits were increased overjet and deep overbite. To conclude, malocclusion remained prevalent in the primary dentition and varied between countries.

Genetic Insights into Skeletal Malocclusion: The Role of the FBN3 rs7351083 SNP in the Romanian Population

Background and Objectives: irregularities in the growth and development of the jawbones can lead to misalignments of maxillary and mandibular structures, a complex condition known as skeletal malocclusion, one of the most common oral health problems. Skeletal malocclusions, particularly Class II and Class III, can significantly affect facial appearance, chewing efficiency, speech, and overall oral health, often requiring orthodontic treatment or surgery to correct. These dentofacial anomalies are influenced by genetic and environmental factors and exhibit diverse phenotypic expressions. Materials and Methods: in this study, we investigated the correlation between the rs7351083 SNP of the FBN3 gene that encodes a member of the fibrillin protein family and malocclusion risk in a group of 57 patients from Romania. Results: the results shed light on the relationship between the selected genetic marker and the investigated dentofacial disorder, revealing a positive association between the reference allele (A) and Class II and that the alternate allele (G) is associated with Class III. Conclusions: cephalometric analysis revealed no significant differences among genotypes, suggesting that while genetic factors are implicated in malocclusion, they may not directly affect cephalometric parameters or that the sample size was too small to detect these differences. The discovery of an A > T transversion in one individual with a Class II deformity underscores the genetic diversity within the population and the necessity of comprehensive genotyping to uncover rare genetic variants that might influence craniofacial development and the risk of malocclusion. This study highlights the need for larger studies to confirm these preliminary associations.

Long-term effects produced by early treatment of Class III malocclusion with rapid maxillary expansion and facemask followed by fixed appliances: A multicentre retro-prospective controlled study

OBJECTIVE

To assess the short- and long-term dentoskeletal effects of early Class III treatment with rapid maxillary expansion and facemask (RME/FM) followed by fixed appliances.

MATERIALS AND METHODS

A total of 44 patients (27 females, 17 males) treated consecutively with RME/FM were included from the archives of 3 centres. Three lateral cephalograms were available: T0 (before the start of RME/FM therapy, mean age 8.1 ± 1.8 years), T1 (immediately after RME/FM, mean age 9.8 ± 1.6 years), and T2 (long-term observation, mean age 19.5 ± 1.6 years). A control group of 17 untreated Class III subjects (12 females and 5 males) also was selected. Between-group statistical comparisons were performed with ANCOVA.

RESULTS

No statistically significant differences for any of the cephalometric variables were found at T0. In the short term, the treated group showed significant improvements in ANB (+2.9°), Wits appraisal (+2.7 mm), SNA (+1.8°) and SNB (-1.1°). A significant closure of CoGoMe angle (-1.3°) associated with smaller increments along Co-Gn (-2.4 mm) also was found together with a significant increase in intermaxillary divergence (+1.3°). In the long-term, significant improvements in ANB (+2.6°), Wits appraisal (+2.7 mm) and SNB (-1.7°) were recorded together with a significant closure of the CoGoMe angle (-2.9°). No significant long-term changes in vertical skeletal relationships were found.

CONCLUSIONS

RME/FM therapy was effective in improving Class III dentoskeletal relationships in the short term. These changes remained stable in the long-term due mainly to favourable mandibular changes.

Craniofacial syndromes and class III phenotype: common genotype fingerprints? A scoping review and meta-analysis

Skeletal Class III (SCIII) is among the most challenging craniofacial dysmorphologies to treat. There is, however, a knowledge gap regarding which syndromes share this clinical phenotype. The aims of this study were to: (i) identify the syndromes affected by the SCIII phenotype; (ii) clarify the involvement of maxillary and/or mandibular structures; (iii) explore shared genetic/molecular mechanisms. A two-step strategy was designed: [Step#1] OMIM, MHDD, HPO, GeneReviews and MedGen databases were explored; [Step#2]: Syndromic conditions indexed in [Step#1] were explored in Medline, Pubmed, Scopus, Cochrane Library, WOS and OpenGrey. Eligibility criteria were defined. Individual studies were assessed for risk of bias using the New Ottawa Scale. For quantitative analysis, a meta-analysis was conducted. This scoping review is a hypothesis-generating research. Twenty-two studies met the eligibility criteria. Eight syndromes affected by the SCIII were targeted: Apert syndrome, Crouzon syndrome, achondroplasia, X-linked hypohidrotic ectodermal dysplasia (XLED), tricho-dento-osseous syndrome, cleidocranial dysplasia, Klinefelter and Down syndromes. Despite heterogeneity between studies [p < 0.05], overall effects showed that midface components were affected in Apert and Down Syndromes, lower face in Klinefelter Syndrome and midface and lower face components in XLED. Our review provides new evidence on the craniofacial characteristics of genetically confirmed syndromes exhibiting the SCIII phenotype. Four major regulatory pathways might have a modulatory effect on this phenotype. IMPACT: What does this review add to the existing literature? To date, there is no literature exploring which particular syndromes exhibit mandibular prognathism as a common trait. Through this research, it was possibly to identify the particular syndromes that share the skeletal Class III phenotype (mandibular prognathism) as a common trait highlighting the common genetic and molecular pathways between different syndromes acknowledging their impact in craniofacial development.

Expert consensus on pediatric orthodontic therapies of malocclusions in children

Malocclusion, identified by the World Health Organization (WHO) as one of three major oral diseases, profoundly impacts the dental-maxillofacial functions, facial esthetics, and long-term development of ~260 million children in China. Beyond its physical manifestations, malocclusion also significantly influences the psycho-social well-being of these children. Timely intervention in malocclusion can foster an environment conducive to dental-maxillofacial development and substantially decrease the incidence of malocclusion or reduce the severity and complexity of malocclusion in the permanent dentition, by mitigating the negative impact of abnormal environmental influences on the growth. Early orthodontic treatment encompasses accurate identification and treatment of dental and maxillofacial morphological and functional abnormalities during various stages of dental-maxillofacial development, ranging from fetal stages to the early permanent dentition phase. From an economic and societal standpoint, the urgency for effective early orthodontic treatments for malocclusions in childhood cannot be overstated, underlining its profound practical and social importance. This consensus paper discusses the characteristics and the detrimental effects of malocclusion in children, emphasizing critical need for early treatment. It elaborates on corresponding core principles and fundamental approaches in early orthodontics, proposing comprehensive guidance for preventive and interceptive orthodontic treatment, serving as a reference for clinicians engaged in early orthodontic treatment.

[Role of Fibroblast Growth Factor 7 in Craniomaxillofacial Development]

Craniomaxillofacial development involves a series of highly ordered temporal-spatial cellular differentiation processes in which a variety of cell signaling factors, such as fibroblast growth factors, play important regulatory roles. As a classic fibroblast growth factor, fibroblast growth factor 7 (FGF7) serves a wide range of regulatory functions. Previous studies have demonstrated that FGF7 regulates the proliferation and migration of epithelial cells, protects them, and promotes their repair. Furthermore, recent findings indicate that epithelial cells are not the only ones subjected to the broad and powerful regulatory capacity of FGF7. It has potential effects on skeletal system development as well. In addition, FGF7 plays an important role in the development of craniomaxillofacial organs, such as the palate, the eyes, and the teeth. Nonetheless, the role of FGF7 in oral craniomaxillofacial development needs to be further elucidated. In this paper, we summarized the published research on the role of FGF7 in oral craniomaxillofacial development to demonstrate the overall understanding of FGF7 and its potential functions in oral craniomaxillofacial development.

East Asian and Southern European craniofacial class III phenotype: two sides of the same coin?

OBJECTIVES

The skeletal class III phenotype is a heterogeneous condition in populations of different ethnicities. This study aimed to analyse the joint and ethnicity-specific clustering of morphological features in skeletal class III patients of Asian and European origins.

MATERIALS AND METHODS

This cross-sectional study involved South Korean and Spanish participants who fulfilled the cephalometric, clinical, and ethnic-related selection criteria. Radiographic records were standardised, calibrated, and measured. A total of 54 skeletal variables were selected for varimax factorial analysis (VFA). Subsequently, a cluster analysis (CA) was performed (mixed method: k-means and hierarchical clustering). Method error and precision were assessed using ICC, Student's t-test, and the Dahlberg formula.

RESULTS

A total of 285 Korean and Spanish participants with skeletal class III malocclusions were analysed. After performing VFA and CA, the joint sample revealed three global clusters, and ethnicity-specific analysis revealed four Korean and five Spanish clusters. Cluster_1_global was predominantly Spanish (79.2%) and male (83.01%) and was characterised by a predominantly mesobrachycephalic pattern and a larger cranial base, maxilla, and mandible. Cluster_2_global and Cluster_3_global were mainly South Korean (73.9% and 75.6%, respectively) and depicted opposite phenotypes of mandibular projection and craniofacial pattern.

CONCLUSIONS

A distinct distribution of Spanish and South Korean participants was observed in the global analysis. Interethnic and interethnic differences were observed, primarily in the cranial base and maxilla size, mandible projection, and craniofacial pattern.

CLINICAL RELEVANCE

Accurate phenotyping, reflecting the complexity of skeletal class III phenotype across diverse populations, is critical for improving diagnostic predictability and future personalised treatment protocols.

Skeletal Class III phenotype: Link between animal models and human genetics: A scoping review

This study aimed to identify evidence from animal studies examining genetic variants underlying maxillomandibular discrepancies resulting in a skeletal Class III (SCIII) malocclusion phenotype. Following the Manual for Evidence Synthesis of the JBI and the PRISMA extension for scoping reviews, a participant, concept, context question was formulated and systematic searches were executed in the PubMed, Scopus, WOS, Scielo, Open Gray, and Mednar databases. Of the 779 identified studies, 13 met the selection criteria and were included in the data extraction. The SCIII malocclusion phenotype was described as mandibular prognathism in the Danio rerio, Dicentrarchus labrax, and Equus africanus asinus models; and as maxillary deficiency in the Felis silvestris catus, Canis familiaris, Salmo trutta, and Mus musculus models. The identified genetic variants highlight the significance of BMP and TGF-β signaling. Their regulatory pathways and genetic interactions link them to cellular bone regulation events, particularly ossification regulation of postnatal cranial synchondroses. In conclusion, twenty genetic variants associated with the skeletal SCIII malocclusion phenotype were identified in animal models. Their interactions and regulatory pathways corroborate the role of these variants in bone growth, differentiation events, and ossification regulation of postnatal cranial synchondroses.

Maxillary Protraction: A Bibliometric Analysis

OBJECTIVES

The aim of this analysis was to investigate the historical development, current status, and research hot spots related to maxillary protraction in the treatment of maxillary hypoplasia.

METHODS

The term "TS = maxillary protraction" was used to search for articles in the Web of Science Core Collection at the library of Capital Medical University. The results were analysed using CiteSpace6.2.R1 software, including the examination of annual publication trends and analysis of author, country, institution, and keywords.

RESULTS

A total of 483 papers were included in this study. The annual publications showed an overall increasing trend. The top 5 authors with the most published papers were Lorenzo Franchi, Tiziano Baccetti, Seung-Hak Baek, Paola Cozza, and U Hagg. The top 5 countries with the highest publication counts were the US, Turkey, South Korea, Italy, and China. The top 5 institutions in terms of the number of published papers were the University of Florence, the University of Michigan, Kyung Hee University, Seoul National University, and Gazi University. The top 3 journals with the most citations were the American Journal of Orthodontics and Dentofacial Orthopedics, Angle Orthodontist, and the European Journal of Orthodontics. Furthermore, "Maxillary protraction," "Class III malocclusion," and "Maxillary expansion" were the most common keywords.

CONCLUSIONS

The effective age range for maxillary protraction has been expanded with the introduction of skeletal anchorage and the combination of maxillary expansion and protraction. Skeletal anchorage offers significant advantages over dental anchorage, but there is a need for further research to further substantiate its stability and safety. In recent years, the positive effects of maxillary protraction on the nasopharyngeal area have been well established, but its impact on the oropharyngeal area remains a topic of debate. Therefore, it is crucial to conduct further investigations into the effects of maxillary protraction on the oropharyngeal area and explore the factors that influence different outcomes.

Efficacy of Clear Aligners in Treating Class III Malocclusion With Mandibular Molar Distalization: A Systematic Review

The primary goal of orthodontic therapy in pseudo-class III is to restore the proper dental connection by rectifying the canine and molar relationship to Class I through lower molar and premolar visualization, as well as providing normal anterior overjet. The purpose of this systematic study was to determine the efficacy of clear aligners in treating class III malocclusion with mandibular molar distalization. A wide range of searches were done on various search engines like Cochrane, Web of Science, Embase, PubMed, Scopus, and Google Scholar to collect relevant articles related to our study. This review's article selection was guided by the PRISMA flowchart. The electronic findings provided numerous articles with nearly 78 articles regarding clear aligners in class III malocclusion with molar distalization. From this, seven full-text papers were evaluated for eligibility criteria, with two articles being rejected with justification and five articles being elaborated in the current systematic review. The current evidence of this review suggested that the clear aligners were effective in correcting class III malocclusion with molar distalization. The amount of molar distalization is about 2 to 3 mm, which helps in achieving molar and canine relationship in class I, with a high compliance level and also improvement of the facial profile.

Three-dimensional phenotype characteristics of skeletal class III malocclusion in adult Chinese: a principal component analysis-based cluster analysis

BACKGROUND

Skeletal class III malocclusion has a diverse and complicated aetiology involving environmental and genetic factors. It is critical to correctly classify and define this malocclusion to be diagnosed and treated on a clinically sound basis. Thus, this study aimed to provide reliable and detailed measurements in a large ethnically homogeneous sample of Chinese adults to generate an adequate phenotypic clustering model to identify and describe the skeletal variation present in skeletal class III malocclusion.

MATERIALS AND METHODS

This is a retrospective cross-sectional study in which 500 pre-treatments cone-beam computed tomography (CBCT) scans of patients with skeletal class III malocclusion (250 males and 250 females) were selected following specific selection criteria. Seventy-six linear, angular, and ratios measurements were three-dimensionally analysed using InVivo 6.0.3 software. These measurements were categorised into 47 skeletal, 18 dentoalveolar, and 11 soft tissue variables. Multivariate reduction methods: principal component analyses and cluster analyses were used to present the most common phenotypic groupings of skeletal class III malocclusion in Han ethnic group of Chinese adults.

RESULTS

The principal component analysis revealed eight principal components accounted for 72.9% of the overall variation of the data produced from the seventy-six variables. The first four principal components accounted for 53.37% of the total variations. They explained the most variation in data and consisted mainly of anteroposterior and vertical skeletal relationships. The cluster analysis identified four phenotypes of skeletal class III malocclusion: C1, 34%; C2, 11.4%; C3, 26.4%; and C4, 28.2%.

CONCLUSION

Based on three-dimensional analyses, four skeletal class III malocclusion distinct phenotypic variations were defined in a large sample of the adult Chinese population, showing the occurrence of phenotypic variation between identified clusters in the same ethnic group. These findings might serve as a foundation for accurate diagnosis and treatment planning of each cluster and future genetic studies to determine the causative gene(s) of each cluster.

An Anthropological Investigation of the Sociocultural and Economic Forces Shaping Dental Crowding Prevalence

OBJECTIVE

The aim of the current study is to explore country of origin and social race category differences in dental crowding prevalence through an anthropological approach.

DESIGN

Data were collected from individuals within five countries (Australia, China, Japan, South Africa, United States; n = 1008) and seven social race groups in two countries (American Black, American White, Latinx, and Indigenous in the United States, South African Black, South African White, and South African Coloured; n = 654). Statistical significance between groups was assessed with a Kruskal-Wallis test, while a Dunn's post-hoc test identified which groups significantly differed.

RESULTS

Results indicate South Africa is characterized by the lowest frequencies of dental crowding, with Coloured South Africans yielding the highest and Black South Africans displaying the lowest frequencies. Individuals in the United States exhibited relatively high levels of minor dental crowding. American Blacks had lower crowding levels, while the Indigenous group had high levels of severe crowding. Individuals within China and Japan exhibited higher relative prevalence of severe crowding.

CONCLUSIONS

Overall, significant differences exist in dental crowding prevalence across countries and social race categories using an anthropological grading system to assess crowding. These differences are likely impacted by sociocultural (aesthetic preferences) and economic (access to dental care) factors.

Single nucleotide polymorphisms MYO1H 1001 C>T SNP (rs3825393) is a strong risk factor for mandibular prognathism

INTRODUCTION

Mandibular prognathism (MP) is a common craniofacial disorder of Class III malocclusion that causes esthetic and functional problems. Class III malocclusion diversity is influenced by both environmental and genetic factors. Single nucleotide polymorphisms (SNPs) in genes involved in craniofacial morphogenesis, bone and cartilage development, and metabolism, could play a role as predisposing factors. The present study aimed to establish a potential association between MATN1 -1878 A>G (rs1149048), MYO1H 1001 C>T (rs3825393), and BMP-4 538 A>G (rs17563) SNPs and MP in Serbian population.

METHODS

The study included 110 participants: 55 patients with Class III malocclusion diagnosed with MP and 55 with Class I malocclusion. The 3 SNPs were analyzed using the polymerase chain reaction-restriction fragment length polymorphism method.

RESULTS

The genotype frequency of MYO1H showed a highly significant difference between patients and controls. Heterozygous carriers of the T allele had an almost 3-fold increase in odds for the development of MP (odds ratio, 2.79; 95% confidence interval, 1.26-6.19; P = 0.010). No association could be established between MATN1 and BMP-4 polymorphisms and MP.

CONCLUSIONS

Our results support the concept of gene polymorphisms as risk modulators in mandibular prognathism development, although only the association between MYO1H and MP was found in Serbian patients with Class III malocclusion.

Difference in Using Protrusion Face Mask before or after Rapid Palatal Expansion in Skeletal Class III Children: A Preliminary Study

Treatment of third-class malocclusions often presents a challenge for orthodontists. Skeletal disharmony is often associated with dental malposition. There are several therapeutic choices, including the use in combination of transverse expansion of the maxilla with rapid palatal expander (RPE) and posterior-anterior traction with a Delaire face mask (FM). The purpose of the study is to verify whether there are significant differences in the treatment outcome in the case of use of a face mask followed by a palatal expander or with the sequence of these auxiliaries reversed. Subject and Methods: The two groups were both made up of 13 patients, subdivided into group A, i.e., those whose sequence involved the use of extraoral traction first and then the disjunctor, and those with an inverted sequence in group B. Some cephalometric parameters and dento-skeletal characteristics were evaluated pre-treatment (t0) and at the end of therapy (t1). Results: Considering the T1-T0 of group A (Delaire + rapid palatal expander), the evaluation of the results obtained in this work allows us to observe how within group A there is a significant improvement in the Witts and Nanda indices and facial convexity. Group B (treated with the palate disjunctor sequence followed by traction with Delaire's mask) showed a significant improvement in ANB, in AoBo, and AppBpp values and in convexity. The two groups were comparable, and no statistically significant difference was highlighted. Discussion: The early therapy of the third skeletal classes by means of a rapid palate expander and face mask is effective. There is no statistically significant difference in the two groups who performed the therapy in reverse mode. This suggests that the clinician should choose the treatment sequence based on the skeletal and occlusal conditions of their patients at the start of treatment. Conclusion: Early therapy of third skeletal classes with sagittal expansion using a rapid palate expander can be performed earlier or later than posterior-anterior traction with a Delaire mask.

Skeletal Class III Malocclusion Is Associated with ADAMTS2 Variants and Reduced Expression in a Familial Case

Skeletal Class III malocclusion with maxillary deficiency is a severe maxillofacial disease with unclear pathogenic mechanisms. We recruited a Han Chinese family who was clinically diagnosed with skeletal Class III malocclusion and maxillary deficiency. Using whole exome sequencing, a missense variant in ADAMTS2 (NM_014244: c.3506G>T: p.G1169V) was identified and predicted as deleterious by in silico tools. We also found ADAMTS2 variants associated with deficient maxillary development in a cohort. ADAMTS2 expression in HEK293 cells showed significant decrease due to the variant, which was also consistent in dental pulp stem cells from the proband and a healthy control. In the adamts2-knockdown zebrafish model, the length and width of the ethmoid plate, as well as the length of the palatoquadrate became significantly shorter than the control group (p < 0.001), while there was no significant difference in the length and width of the mandible. The expression of Sox3, which was required in early embryonic craniofacial development, was significantly downregulated in the adamts2-knockdown zebrafish embryos. Bioinformatic and cellular studies showed that the decreased expression of ADAMTS2 may inhibit downstream ErbB signaling pathway transduction and restrain subsequent osteogenesis in human adult mesenchymal stromal cells. Collectively, these data showed that ADAMTS2 (c.3506G>T: p.G1169V) may confer susceptibility to risk of skeletal Class III malocclusion with maxillary deficiency.

The association of polymorphisms in BMP2/MYO1H and skeletal Class II div.1 maxillary and mandibular dimensions. A preliminary ‘report

Introduction

The genetic impact directly or indirectly predefines maxillofacial dimensions, potentially leading to an inappropriate relationship of the jaws and subsequently skeletal malocclusion. Previous studies focused mainly on genetic polymorphisms and class III malocclusion. This study was set out to investigate the association between genetic polymorphisms in two genes BMP2 (rs235768) and MYO1H (rs11066446) with Class II division 1 malocclusion, skeletal variation in vertical plane, and maxillary and mandibular jaws length.

Subjects and methods

Sixty patients classified as Skeletal Class I (n = 30) and Class II division 1 (n = 30) were recruited. DNA was extracted from saliva and analyzed by Sanger sequencing. Lateral cephalometric radiographs were measured for the anterio-posterior relationship of maxillary and mandibular arch using digital tracing. Hardy-Weinberg equilibrium analysis of genotype frequencies was performed using Chi-square test to compare genotype distribution among groups and multiple logistic regression analysis adjusted by gender was also performed.

Results

The rs235768 polymorphism in BMP2 was associated with hypodivergent face, increased maxillary length, and decreased mandibular length. Meanwhile, the rs11066446 polymorphism in MYO1H was associated with decreased mandibular length. New polymorphism was identified in MYO1H (rs10850090) in association with decreased mandibular length.

Conclusion

A potential association between polymorpisms in BMP2 rs235768 and MOY1H rs11066446 and rs10850090 and Class II division 1 skeletal malocclusion related phenotypes exists, however, the degree of it has to be further investigated and yet to be discovered.

Lower Molar Distalization Using Clear Aligners: Bodily Movement or Uprighting? A Preliminary Study

Background: Lower molar distalization is considered to be one of the most difficult movements to obtain with clear aligners. The aim of this study was to evaluate the possibility to distalize the lower molars using clear aligners in adults without miniscrews. Material and methods: rx cephalograms of 16 patients (8 males, 8 females; mean age of 25.6 years), who underwent lower molar distalization, were analyzed. Cephalograms were taken before the beginning of treatment (T0) and after the end of treatment (T1). Dental and skeletal changes between T0 and T1 were evaluated. The level of significance was set at p < 0.05. Results: At T1, the lower second molar moved distally 2.47 mm, but there was a significant tipping (p = 0.027); the same result was found at the first molar, with a mean distal movement of 1.16 mm and a significant tipping (p = 0.003). No significant changes were detected on the sagittal and vertical skeletal variables. Conclusion: Clear aligner therapy can provide more distal tipping than bodily movement in the lower molars when a distalization is programmed. This movement could be sufficient to correct the initial malocclusion and gain a class I molar relationship.

Transforming Growth Factor Beta Receptor 2 (TGFBR2) Promoter Region Polymorphisms May Be Involved in Mandibular Retrognathism

Skeletal malocclusions are common phenotypes in humans and have a strong influence on genetic factors. Transforming growth factor beta (TGFβ) controls numerous functions of the human body, including cell proliferation, differentiation, and migration. Thus, this study is aimed at evaluating whether genetic polymorphisms in TGFB1 and its receptor TGFBR2 are associated with mandibular retrognathism in German children and adolescents. Children and teenagers older than 8 years in the mixed or permanent dentition were included in this study. Patients with syndromes and facial trauma and patients with congenital alterations were excluded. Digital cephalometric tracings were performed using the anatomical landmarks point A, point B, sella (S), and nasion (N). Patients that have a retrognathic mandible (SNB < 78°) were selected as case group, and the patients with an orthognathic mandible (SNB = 78°– 82°) were selected as the control group. Genomic deoxyribonucleic acid (DNA) from saliva was used to evaluate four genetic polymorphisms in TGFB1 (rs1800469 and rs4803455) and TGBR2 (rs3087465 and rs764522) using real-time PCR. Chi-square or Fisher exact tests were used to compare gender, genotype, and allele distribution among groups. Genotype distribution was calculated in an additive and recessive model. Haplotype analysis was also performed. The established alpha of this study was 5%. A total of 146 patients (age ranging from 8 to 18 years) were included in this epidemiological genetic study. The genetic polymorphism rs3087465 in TGFBR2 was associated with mandibular retrognathism. Carrying the AA genotype in the rs3087465 polymorphism decreased the chance of having mandibular retrognathism (odds ratio = 0.25, confidence interval 95% = 0.06 to 0.94, p = 0.045). None of the haplotypes was associated with mandibular retrognathism (p > 0.05). In conclusion, we found that the genetic polymorphism rs3087465 in the promoter region of the TGFBR2 was associated with mandibular retrognathism in Germans.

Assessment of Golden Proportion among Natural Maxillary Anterior Teeth of Global Population: A Systematic Review

The purpose of this systematic review was to analyze studies, identify the existence of golden proportion between the perceived widths of the maxillary anterior teeth among the different geographical populations, and evaluate the range of dental proportion that exists regionally. An electronic search was conducted using PubMed, Medline, EMBASE, Scopus, Science Direct, Web of Science, and the Cochrane Library. The focused question was, “Does golden proportion exist in natural, aesthetically pleasing smiles among different populations around the world?” The search conducted included studies from January 2000 to September 2020, identifying articles in English with the specific combination of MeSH and other related terms. The title search yielded eight hundred and ninety-eight articles, and seventy-five articles were selected for full-text analysis. However, only fifty-two full-text articles were included in the systematic review. The mean predicted dental ratios were either larger or smaller than the successive widths of maxillary natural anterior teeth. Golden proportions were not found consistently among anterior teeth in different populations observed in the systematic review. The golden proportion is still a useful tool for the reconstruction of lost or damaged anterior tooth widths; however, it is not the only standard for restoring esthetic smiles worldwide, and anterior tooth proportions differ among populations based on their geographic, ethnic, and racial background. Moreover, consideration should also be given to an individual’s dentofacial variations in restoring anterior teeth.

Treatment of Class III Malocclusion and Anterior Crossbite with Aligners: A Case Report

The article describes the orthodontically treated case of a 25-year-old patient with skeletal and dental class III malocclusion, anterior crossbite, which caused functional and aesthetic problems, occlusal trauma, and incisor wear. Treatment with transparent aligners was proposed to meet the patient's needs, using the sequential distalization protocol. While sequential distalization is well documented for class II malocclusion treatment in maxillary arch teeth, further investigations are necessary for class III malocclusions. In fact, lower teeth movements are more complex due to mandibular bone density and the presence of the third molars, which are often extracted to perform distalization. In addition, the use of intermaxillary elastics helps control the proclination of the anterior teeth as a reaction to distalizing forces. At the end of the treatment, the patient reached molar and canine class I and positive overjet and overbite. The inclination of lower incisors and the interincisal angle have improved, resulting in aesthetic and functional enhancement.

Orthognathic versus Camouflage Treatment of Class III Malocclusion: A Systematic Review and Meta-Analysis

This systematic review (SR) and meta-analysis (MA) aimed to compare the treatment effects of orthognathic surgery and orthodontic camouflage treatment in adult subjects with Class III malocclusion (C-III-M). Two independent reviewers conducted the literature search comprehensively from 1990 to 8 November 2021. PubMed, Science Direct, Scopus, EBSCOhost and Google Scholar databases were included for literature search. Moreover, a manual search of references from relevant studies was performed. Based on the literature search, a total of six articles were selected for SR and three articles fulfilled the criteria of a MA. Standardized mean difference (SMD) was used to evaluate and compare the treatment effects of orthodontic camouflage treatment and orthognathic surgery in adult C-III-M patients. Test for overall effect from the studies was used to estimate the treatment effect of C-III-M. However, Significant heterogeneity and publication bias was apparent among the selected studies. More research on the treatment effects of orthodontic camouflage treatment and orthognathic surgery in C-III-M is necessary to conclude possible interactions with better specificity.

A retrospective long-term comparison of early RME-facemask versus late Hybrid-Hyrax, alt-RAMEC and miniscrew-supported intraoral elastics in growing Class III patients

OBJECTIVE

To compare the long-term dentoskeletal effects of early treatment with banded or bonded RME (Rapid Maxillary Expansion)-Face Mask (RME-FM) versus late treatment with bonded Hybrid-Hyrax, alt-RAMEC (Alternate Rapid Maxillary Expansion and Contraction) and intraoral Class III elastics anchored to miniscrew-reinforced-Lower-lingual-Arch (alt-RAMEC-HH-LLA) in growing, maxillary retrognathic patients.

MATERIALS AND METHODS

Two groups were matched at long-term follow-up retrospectively. Patients received either early RME-FM (n=16, 5 males, 11 females, age T1: 6.5±0.9 years, age T2: 15.8±2.5 years) or late alt-RAMEC-HH-LLA (n=15, 7 males, 8 females, age T1: 12.52±0.94 years, age T2: 16.8±0.9 years). Total follow-up was 9.2±2.3 years and 4.2±0.2 years respectively, including fixed appliances to compete treatment.

RESULTS

Both treatments resulted in Class III correction except one unsuccessful case of alt-RAMEC-HH-LLA. Active maxillary protraction was 1.6±0.5years with RME-FM and 0.5 years with alt-RAMEC-HH-LLA being significantly shorter (P<0.001). Values at T2 estimation with multivariate linear regression for correlated multiple outcomes, conditional on baseline estimates, age and sex showed alt-RAMEC-HH-LLA inducing significantly more retroclined lower incisors (mean: -6.11°; 95%CI: -10.66, -1.57; P=0.01), less overbite (mean: -1.28mm; 95%CI: -1.79, -0.761; P<0.001), less maxillo (Co-A)- (mean: -4.54mm; 95%CI: -7.91, -1.16; P=0.01) mandibular (Co-Gn) (mean: -10.5mm; 95%CI: -17.45, -3.55; P=0.003) projections/size, more open gonial angle (mean: 4.93°; 95%CI: 2.27, 7.59; P<0.001), and less S-N length (mean: -5.04mm; 95%CI: -6.57, -3.51; P<0.001).

CONCLUSIONS

Patients treated with either early RME-FM or late Alt-RAMEC-HH-LLA had comparable overall post-pubertal skeletal and overjet corrections. However, the late Alt-RAMEC-HH-LLA showed less correction of dentoalveolar compensations and in particular of the mandibular incisors. The overbite, maxillary and mandibular projection and size were lower and the gonial angle was more open.

Postoperative stability of two common ramus osteotomy procedures for the correction of mandibular prognathism: A randomized controlled trial

The aim of this randomized controlled trial was to compare the skeletal stability between sagittal split ramus osteotomy (SSRO) and intraoral vertical ramus osteotomy (IVRO) in the treatment of mandibular prognathism. Patients presenting with mandibular prognathism and scheduled for orthognathic surgery were randomized into either the SSRO group or the IVRO group. Changes at B-point were assessed by serial tracing of lateral cephalograms, which were taken preoperatively, and at 2 weeks, 6 months, 1 year, and 2 years postoperatively. Ninety-eight patients were recruited, with 49 patients in each group. Between 2 weeks and 6 months postoperatively, there was significantly more surgical relapse in the horizontal direction (anterior movement) in the SSRO group when compared with the IVRO group (1.83 mm (SD 2.91 mm) vs 0.49 mm (SD 2.32 mm); p = 0.019). At 2 years, there was more surgical relapse in the horizontal direction in the SSRO group than in the IVRO group (0.27 mm (SD 0.34 mm) vs 0.10 mm (SD 0.29 mm); p = 0.014). There were also more absolute changes (irrespective of direction) at B-point in the SSRO group than in the IVRO group at postoperative 6 months, 1 year, and 2 years (p = 0.016, 0.049, and 0.045, respectively). The amounts of change at B-point as percentages of total mandibular setback were 1.3% and 3.5% in the IVRO group and SSRO group, respectively. There were no differences in vertical changes between the two groups at any time points. In conclusion, the horizontal stability at B-point was shown to be superior in the IVRO group compared with the SSRO group in the correction of mandibular prognathism during the 2-year follow-up. Although the exact clinical importance of this difference is unknown at this time, this possible benefit may be an important key factor when deciding which osteotomy technique to employ for mandibular setback.

Surgical-Orthodontic Diagnosis and Treatment Planning in an Asymmetric Skeletal Class III Patient—A Case Report

The skeletal Class III pattern is characterized by a sagittal intermaxillary mesial discrepancy. This discrepancy may have an unfavorable impact on function and aesthetics, which can be aggravated by the presence of facial asymmetries. This case report describes the diagnosis and treatment planning of a 19-year-old male patient with a skeletal Class III, maxillary hypoplasia, anterior crossbite, and mandibular asymmetry. When the patient reached skeletal maturity at the end of puberty, the definitive diagnosis was skeletal Class III with hyperdivergent profile and mandibular asymmetry, and a surgical-orthodontic treatment was proposed. At the end of the treatment, bimaxillary surgical correction allowed a skeletal Class I with mandibular symmetry, improving the function of the stomatognathic system and facial aesthetics.

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.