Evidence of Association between MTRR and TNF-α Gene Polymorphisms and Oral Health-Related Quality of Life in Children with Anterior Open Bite.

Genetic polymorphisms could explain the inter-individual differences in the oral health-related quality of life (OHRQoL) of children with anterior open bite (AOB). OBJECTIVE: To assess the impact of AOB on OHRQoL in children and to evaluate whether MTR (rs1805087), MTRR (rs1801394), TGFß1 (rs1800469) and TNF-α (rs1799964, rs1799724 and rs1800629) genes are potential biomarkers for OHRQoL in children with AOB. STUDY DESIGN: A cross-sectional study was performed with 173 children aged between 2-6 years. The Brazilian version of Early Childhood Oral Health Impact Scale (ECOHIS) was applied. Genetic polymorphisms were analyzed using real-time PCR. Mann-Whitney U-test and Chi-square were used. RESULTS: The overall mean ECOHIS scores were 5.49 (SD= 5.72) and 3.45 (SD = 4.49) (p < 0.01) in the AOB and control groups, respectively. Children with the CC genotype of TNF-α (rs1799724) had a significantly higher psychological QoL level. The MTRR AA genotype group showed a lower QoL level in the child subscale (p = 0.006), function (p = 0.017), and psychological (p = 0.006) domains. There was no significant difference between OHRQoL and the genetic polymorphisms in MTR and TGFß1. CONCLUSIONS: Genetic polymorphisms in TNF-α and MTRR are associated with the impact on the OHRQoL in children with AOB.

Genetic Polymorphism in MMP9 May Be Associated With Anterior Open Bite in Children

Abstract Anterior open bite (AOB) has a multifactorial etiology caused by the interaction of sucking habits and genetic factors. The aim of this study was to evaluate the association between AOB and polymorphisms in genes that encode Matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs). Four hundred and seventy-two children that presented at least one sucking habit were evaluated. Children were examined clinically for the presence of AOB. Genomic DNA was extracted from saliva. Genotyping of the selected polymorphisms in MMP2, MMP3, MMP9, TIMP1 and TIMP2 was carried out by real-time PCR using the TaqMan method. Allele and genotype frequencies were compared between the groups with and without AOB using the PLINK® software in a free and in a recessive model using a chi-square test. Logistic regression analysis was implemented (p≤0.05). Two hundred nineteen children had AOB while 253 did not. The polymorphism rs17576 in MMP9 was significantly associated with AOB (p=0.009). In a recessive model GG genotype was a protective factor for AOB (p=0.014; OR 4.6, 95%CI 1.3-16.2). In the logistic regression analysis, none of the genes was associated with AOB. In conclusion, the polymorphism rs17576 (glutamine for arginine substitution) in MMP9 was a protective factor for AOB.

Resumo A mordida aberta anterior apresenta uma etiologia multifatorial causada pela interação entre hábitos de sucção e fatores genéticos. O objetivo deste estudo foi avaliar a associação entre mordida aberta anterior e polimorfismo nos genes que codificam as metaloproteinases da matriz (MMPs) e seus inibidores teciduais (TIMPs). Foram avaliadas 472 crianças que apresentvam pelo menos um hábito de sucção. As crianças foram clinicamente examinadas para avaliar a presença de mordida aberta anterior. DNA genômico foi extraído da saliva. A genotipagem dos polimorfismos selecionados em MMP2, MMP3, MMP9, TIMP1 e TIMP2 foi realizada por PCR em tempo real, usando o método de TaqMan. As frequências alélicas e genotípicas foram comparadas entre os grupos com e sem mordida aberta anterior usando o software PLINK®. Duzentas e dezenove crianças apresentavam mordida aberta anterior enquanto 253 não a apresentavam. O polimorfismo rs17576 em MMP9 estava significativamente associado com mordida aberta anterior (p=0,009). No modelo recessivo (GG versus AG+AA) o genótipo GG foi um fator protetor para mordida aberta anterior (p=0,014; OR 4,6; 95%CI 1,3- 16,2). Concluindo, o polimorfismo rs17576 (substituição de glutamina por arginina) em MMP9 está associado com mordida aberta anterior. Os resultados obtidos suportam a hipótese de que fatores genéticos estão envolvidos com a etiologia da mordida aberta anterior.

Establishment of integral biomechanical balance in the correction of tongue source skeletal dentomaxillofacial open bite deformities.

The objective of this clinical paper is to demonstrate an effective process to achieve relative long-term functional and aesthetic stability after the treatment of skeletal tongue source open bites. This therapy consisted of applying Delaire's architectural analysis as the cephalometry to make treatment plan corresponding to the patients' own craniomaxillofacial integral architectural structure to achieve the optimal skeletal anteroposterior and vertical position. In addition, glossoplasty and transverse matching of upper and lower arches must be under consideration in the goal of achieving integral biomechanical functional balance and aesthetic harmony. Little relapse of both skeleton and occlusion was found more than 3 years posttreatment. The effect of pararthria correction coursed by lingual functional impediment is also attained.

Epigenetic influence of KAT6B and HDAC4 in the development of skeletal malocclusion.

INTRODUCTION: Genetic influences on the development of malocclusion include heritable effects on both masticatory muscles and jaw skeletal morphology. Beyond genetic variations, however, the characteristics of muscle and bone are also influenced by epigenetic mechanisms that produce differences in gene expression. We studied 2 enzymes known to change gene expressions through histone modifications, chromatin-modifying histone acetyltransferase KAT6B and deacetylase HDAC4, to determine their associations with musculoskeletal variations in jaw deformation malocclusions. METHODS: Samples of masseter muscle were obtained from subjects undergoing orthognathic surgery from 6 malocclusion classes based on skeletal sagittal and vertical dysplasia. The muscles were characterized for fiber type properties by immunohistochemistry, and their total RNA was isolated for gene expression studies by microarray analysis and quantitative real-time polymerase chain reaction. RESULTS: Gene expressions for fast isoforms of myosins and contractile regulatory proteins and for KAT6B and HDAC4 were severalfold greater in masseter muscles from a patient with a deepbite compared with one with an open bite, and genes related to exercise and activity did not differ substantially. In the total population, expressions of HDAC4 (P = 0.03) and KAT6B (P = 0.004) were significantly greater in subjects with sagittal Class III than in Class II malocclusion, whereas HDAC4 tended to correlate negatively with slow myosin type I and positively with fast myosin gene, especially type IIX. CONCLUSIONS: These data support other published reports of epigenetic regulation in the determination of skeletal muscle fiber phenotypes and bone growth. Further investigations are needed to elucidate how this regulatory model might apply to musculoskeletal development and malocclusion.

Menkes disease: report of two cases.

Menkes disease is a rare, autosomal recessive disorder characterized by neuronal degeneration, abnormal hair, malformed connective tissue, mental retardation, and a life span of three years. Previously reported dental findings include a high arched palate, delayed eruption of secondary dentition, and open bite. The case of twin seven-year-old males with Menkes disease is presented, along with previously unreported dental findings of spindle-shaped root resorption patterns on the primary maxillary central and lateral incisors.