Early Treatment of Anterior Crossbite with Eruption Guidance Appliance: A Case Report

The purpose of this investigation was to show how to manage an anterior crossbite in early mixed dentition with an eruption guidance appliance (EGA). The analyzed clinical case reported an anterior crossbite, a bimaxillary retrusion tendency, and a horizontal growth pattern. The anterior crossbite was an unfavorable occlusal condition that could lead to a class III malocclusion growth pattern. An early treatment approach was suggested to reach a correct sagittal jaw relationship. Hence, the selected approach acted on the dentoalveolar sector, aiming to have effects on the posterior vertical dimension and to improve the sagittal jaw's relation. An EGA was selected to treat the patient in early mixed dentition. After 7 months of therapy with night-time use, the dental malocclusion was completely resolved. The patient continued to be treated with the same device, used as active retention. With the EGA treatment, the erupting forces, rather than the active forces, were used to resolve the dental malocclusion. This approach allowed a low compliance requirement and had a minimum psychosocial and psychological impact on the patient. The early treatment was essential to give a functional occlusion and a good balance of the soft perioral tissues and muscles.

Is the "Habsburg jaw" related to inbreeding?

Background: The "Habsburg jaw" has long been associated with inbreeding due to the high prevalence of consanguineous marriages in the Habsburg dynasty. However, it is thought that mandibular prognathism (MP) is under the influence of a dominant major gene.Aim: To investigate the relationship between the "Habsburg jaw" and the pedigree-based inbreeding coefficient (F) as a relative measure of genome homozygosity.Subjects and methods: The degree of MP and maxillary deficiency (MD) of 15 members of the Habsburg dynasty was quantified through the clinical analysis of 18 dysmorphic features diagnosed from 66 portraits.Results: A statistically significant correlation (r = 0.711, p = 0.003) between MP and MD was observed among individuals. Only MP showed a statistically significant positive regression on F as evidenced from univariate analysis (b = 6.36 ± 3.34, p = 0.040) and multivariate analysis (PCA) performed from single dysmorphic features (b = 14.10 ± 6.62, p = 0.027, for the first PC).Conclusion: Both MP and MD are generally involved in the "Habsburg jaw." The results showed a greater sensitivity to inbreeding for the lower third of the face and suggest a positive association between the "Habsburg jaw" and homozygosity and therefore a basically recessive inheritance pattern.

Genetic Factors Involved in Mandibular Prognathism

Mandibular prognathism is defined as an abnormal forward projection of the mandible beyond the standard relation to the cranial base and it is usually categorized as both a skeletal Class III pattern and Angle Class III malocclusion. The etiology of mandibular prognathism is still uncertain, with various genetic, epigenetic, and environmental factors possibly involved. However, many reports on its coexistence in both twins and segregation in families suggest the importance of genetic influences. A multifactorial and polygenic background with a threshold for expression or an autosomal dominant mode with incomplete penetrance and variable expressivity are the most probable inheritance patterns. Linkage analyses have, thus far, shown the statistical significance of such loci as 1p22.1, 1p22.3, 1p32.2, 1p36, 3q26.2, 4p16.1, 6q25, 11q22, 12pter-p12.3, 12q13.13, 12q23, 12q24.11, 14q24.3 to 31.2, and 19p13.2. The following appear among candidate genes: MATN1, EPB41, growth hormone receptor, COL2A1, COL1A1, MYO1H, DUSP6, ARHGAP21, ADAMTS1, FGF23, FGFR2, TBX5, ALPL, HSPG2, EVC, EVC2, the HoxC gene cluster, insulin-like growth factor 1, PLXNA2, SSX2IP, TGFB3, LTBP2, MMP13/CLG3, KRT7, and FBN3. On the other hand, MYH1, MYH2, MYH3, MYH7, MYH8, FOXO3, NFATC1, PTGS2, KAT6B, HDAC4, and RUNX2 expression is suspected to be involved in the epigenetic regulations behind the mandibular prognathism phenotype.

Segregation analysis of mandibular prognathism in Korean orthognathic surgery patients and their families

Objective:

To investigate the existence of genetic influences on the incidence of mandibular prognathism (MP) in Korean Class III patients.

Materials and Methods:

The probands consisted of 100 Class III patients with MP (51 men and 49 women; mean age, 22.1 ± 5.2 years; SNA, 81.2° ± 3.2°; SNB, 84.1° ± 3.9°) who underwent orthognathic surgery. Using three-generation pedigree charts, questionnaires, and clinical examinations, general information and information regarding MP for a total of 3777 relatives of the probands (1911 men and 1866 women) was ascertained. Familial correlations of MP between possible pairs in the pedigree were estimated. Heritability (h2) of MP under various models was estimated. Segregation analysis was conducted under the assumption of the nonpolygenic multivariate logistic model and finite polygenic mixed model. One-, two-, and three-susceptibility-type models were evaluated.

Results:

Among 3777 relatives, 199 (97 men and 102 women) were affected with MP (5.3%). Correlation coefficients of MP incidence in full siblings and in parent-offspring were .2003 and .2036, respectively (all P < .001). The h2 of MP was estimated as 21.5% after adjusting for sex and founder effects. Two- and three–susceptibility-type models showed that the general model fit better than the other models. MP incidence did not have a major gene transmission model and was influenced by numerous minor effect genes and their additive effects.

Conclusion:

These results suggest that the inherited susceptibility to MP in Korean Class III patients might be due to the summation of minor effects from a variety of different genes and/or influence of environmental factors, rather than Mendelian transmission of major genes.