RESUMO
INTRODUCTION: We investigated whether ACTN3, ENPP1, ESR1, PITX1, and PITX2 genes which contribute to sagittal and vertical malocclusions also contribute to facial asymmetries and temporomandibular disorders (TMD) before and after orthodontic and orthognathic surgery treatment. METHODS: One hundred seventy-four patients with a dentofacial deformity were diagnosed as symmetric or subdivided into 4 asymmetric groups according to posteroanterior cephalometric measurements. TMD examination diagnosis and jaw pain and function (JPF) questionnaires assessed the presence and severity of TMD. RESULTS: Fifty-two percent of the patients were symmetric, and 48% were asymmetric. The asymmetry classification demonstrated significant cephalometric differences between the symmetric and asymmetric groups, and across the 4 asymmetric subtypes: group 1, mandibular body asymmetry; group 2, ramus asymmetry; group 3, atypical asymmetry; and group 4, C-shaped asymmetry. ENPP1 SNP-rs6569759 was associated with group 1 (P = 0.004), and rs858339 was associated with group 3 (P = 0.002). ESR1 SNP-rs164321 was associated with group 4 (P = 0.019). These results were confirmed by principal component analysis that showed 3 principal components explaining almost 80% of the variations in the studied groups. Principal components 1 and 2 were associated with ESR1 SNP-rs3020318 (P <0.05). Diagnoses of disc displacement with reduction, masticatory muscle myalgia, and arthralgia were highly prevalent in the asymmetry groups, and all had strong statistical associations with ENPP1 rs858339. The average JPF scores for asymmetric subjects before surgery (JPF, 7) were significantly higher than for symmetric subjects (JPF, 2). Patients in group 3 had the highest preoperative JPF scores, and groups 2 and 3 were most likely to be cured of TMD 1 year after treatment. CONCLUSIONS: Posteroanterior cephalometrics can classify asymmetry into distinct groups and identify the probability of TMD and genotype associations. Orthodontic and orthognathic treatments of facial asymmetry are effective at eliminating TMD in most patients.
Assuntos
Deformidades Dentofaciais/classificação , Deformidades Dentofaciais/genética , Receptor alfa de Estrogênio/genética , Assimetria Facial/classificação , Assimetria Facial/genética , Diester Fosfórico Hidrolases/genética , Pirofosfatases/genética , Transtornos da Articulação Temporomandibular/genética , Adulto , Deformidades Dentofaciais/complicações , Deformidades Dentofaciais/cirurgia , Assimetria Facial/complicações , Assimetria Facial/cirurgia , Feminino , Genótipo , Humanos , Masculino , Procedimentos Cirúrgicos Ortognáticos , Complicações Pós-Operatórias/etiologia , Índice de Gravidade de Doença , Transtornos da Articulação Temporomandibular/etiologiaRESUMO
INTRODUCTION: α-Actinins are myofibril anchor proteins that influence the contractile properties of skeletal muscles. ACTN2 is expressed in slow type I and fast type II fibers, whereas ACTN3 is expressed only in fast fibers. ACTN3 homozygosity for the 577X stop codon (ie, changing 577RR to 577XX, the R577X polymorphism) results in the absence of α-actinin-3 in about 18% of Europeans, diminishes fast contractile ability, enhances endurance performance, and reduces bone mass or bone mineral density. We have examined ACTN3 expression and genetic variation in the masseter muscle of orthognathic surgery patients to determine the genotype associations with malocclusion. METHODS: Clinical information, masseter muscle biopsies, and saliva samples were obtained from 60 subjects. Genotyping for ACTN3 single nucleotide polymorphisms, real-time polymerase chain reaction quantitation of muscle gene message, and muscle morphometric fiber type properties were compared to determine statistical differences between genotype and phenotype. RESULTS: Muscle mRNA expression level was significantly different for ACTN3 single nucleotide polymorphism genotypes (P <0.01). The frequency of ACTN3 genotypes was significantly different for the sagittal and vertical classifications of malocclusion, with the clearest association being elevated 577XX genotype in skeletal Class II malocclusion (P = 0.003). This genotype also resulted in significantly smaller diameters of fast type II fibers in masseter muscles (P = 0.002). CONCLUSION: ACTN3 577XX is overrepresented in subjects with skeletal Class II malocclusion, suggesting a biologic influence during bone growth. ACTN3 577XX is underrepresented in subjects with deepbite malocclusion, suggesting that muscle differences contribute to variations in vertical facial dimensions.