Condyle modeling stability, craniofacial asymmetry and ACTN3 genotypes: Contribution to TMD prevalence in a cohort of dentofacial deformities

Abstract

Craniofacial asymmetry, mandibular condylar modeling and temporomandibular joint disorders are common comorbidities of skeletally disproportionate malocclusions, but etiology of occurrence together is poorly understood. We compared asymmetry, condyle modeling stability and temporomandibular health in a cohort of 128 patients having orthodontics and orthognathic surgery to correct dentofacial deformity malocclusions. We also compared ACTN3 and ENPP1 genotypes for association to clinical conditions. Pre-surgical posterior-anterior cephalometric and panometric radiographic analyses; jaw pain and function questionnaire and clinical examination of TMD; and SNP-genotype analysis from saliva samples were compared to assess interrelationships. Almost half had asymmetries in need of surgical correction, which could be subdivided into four distinct morphological patterns. Asymmetric condyle modeling between sides was significantly greater in craniofacial asymmetry, but most commonly had an unanticipated pattern. Often, longer or larger condyles occurred on the shorter mandibular ramus side. Subjects with longer ramus but dimensionally smaller condyles were more likely to have self-reported TMD symptoms ( p = 0.023) and significantly greater clinical diagnosis of TMD ( p = 0 .000001), with masticatory myalgia most prominent. Genotyping found two significant genotype associations for ACTN3 rs1671064 (Q523R missense) p = 0.02; rs678397 (intronic SNP) p = 0.04 and one significant allele association rs1815739 (R577X nonsense) p = 0.00. Skeletal asymmetry, unusual condyle modeling and TMD are common and interrelated components of many dentofacial deformities. Imbalanced musculoskeletal functional adaptations and genetic or epigenetic influences contribute to the etiology, and require further investigation.

Hyoid Bone Position in Patients with and without Temporomandibular Joint Osteoarthrosis: A Cone-Beam Computed Tomography and Cephalometric Analysis

“…Several studies reported the relation between TMJOA and craniofacial morphology [ 10 , 11 ]. Patients with TMJOA exhibited the retrusion and clockwise rotation of the mandible [ 12 ].…”

Genetic Factors That Affect Asymmetric Mandibular Growth—A Systematic Review

“…After the first selection, there were five human studies that met the above-mentioned requirements: two cross-sectional studies [13,18] and three case-control studies [11,19,20]. Four animal studies were also selected: one case-control study [16] and three experimental studies [21][22][23].…”

“…All authors used twodimensional radiographs for this purpose. Authors used different types of radiographs: Sofyanti et al [18,20] analysed asymmetry with panoramic radiograph and Chung et al [11] and Nicot et al [13] used cephalometric analysis. In article [19], Nicot et al performed diagnosis using different types of radiographs.…”

“…Its asymmetric expression induces the expression of PITX2, a gene that belongs to homeobox genes involved in, among other things, the regulation of organogenesis in all eukaryotes. Apart from the PITX2 mutation, variants of the ACTN3, PITX1, ENPP1, and ESR1 genes are also most often associated with asymmetry within the mandible [10][11][12][13].…”

“…It would also allow for a more complete diagnosis of patients during the qualification for functional/surgical treatment. It is also crucial in the genetic counselling of patients with abnormal facial morphology [11,13].…”