IADR Abstract Archives
Association Between Age, Predicted TMJ Compressive Stress, and Mandibular Length
Objectives: To determine if age, predicted temporomandibular joint (TMJ) compressive stress, and mandibular length were related, as a pilot-test for improved predictability of mandibular orthopedic therapy.
Methods: According to Institutional Review Board oversight, subjects were enrolled based on inclusion criteria: age 10-14 years; skeletal Class II malocclusion with treatment planned for fixed orthopedic appliance therapy to promote mandibular growth; permanent teeth erupted with, at minimum, permanent incisors and first molars present; cervical vertebral maturation stage of 3; and exclusion criteria: history of TMJ trauma, musculoskeletal disease, or craniofacial anomaly; teeth with conditions that would impair participation (caries, large restorations, marked mobility); and inability to follow written or auditory instructions. Cone-beam computed tomography images were used to: estimate mandibular condylar rectilinear loading area based on axial plane dimensions: major axis X minor axis (mm2); measure mandibular length (Co-Gn, mm); and construct three-dimensional geometries of the positions of mandibular condyles and teeth, and positions and orientations of masseter, temporalis, medial and lateral pterygoid, and digastric muscles. These geometries were used in numerical models to predict ipsilateral and contralateral TMJ loads for a 10 N bite-force on right first molars at a range of biting angles. Compressive stresses were calculated by dividing the average predicted TMJ loads by the rectilinear loading area for ipsilateral (right) and contralateral (left) mandibular condyles. Regression analysis was used to test for correlation between age (years), TMJ compressive stress (MPa), and mandibular length (mm).
Results: Seven males and five females met inclusion criteria. Regression analysis of the independent variables age (years) and ipsilateral TMJ compressive stress (MPa), and the dependent variable mandible length (mm) showed a positive correlation (R2=0.52). Increased age and decreased TMJ compressive stress were non-linearly correlated with increased mandibular length.
Conclusions: Age and predicted TMJ compressive stresses were correlated with mandibular length.
Methods: According to Institutional Review Board oversight, subjects were enrolled based on inclusion criteria: age 10-14 years; skeletal Class II malocclusion with treatment planned for fixed orthopedic appliance therapy to promote mandibular growth; permanent teeth erupted with, at minimum, permanent incisors and first molars present; cervical vertebral maturation stage of 3; and exclusion criteria: history of TMJ trauma, musculoskeletal disease, or craniofacial anomaly; teeth with conditions that would impair participation (caries, large restorations, marked mobility); and inability to follow written or auditory instructions. Cone-beam computed tomography images were used to: estimate mandibular condylar rectilinear loading area based on axial plane dimensions: major axis X minor axis (mm2); measure mandibular length (Co-Gn, mm); and construct three-dimensional geometries of the positions of mandibular condyles and teeth, and positions and orientations of masseter, temporalis, medial and lateral pterygoid, and digastric muscles. These geometries were used in numerical models to predict ipsilateral and contralateral TMJ loads for a 10 N bite-force on right first molars at a range of biting angles. Compressive stresses were calculated by dividing the average predicted TMJ loads by the rectilinear loading area for ipsilateral (right) and contralateral (left) mandibular condyles. Regression analysis was used to test for correlation between age (years), TMJ compressive stress (MPa), and mandibular length (mm).
Results: Seven males and five females met inclusion criteria. Regression analysis of the independent variables age (years) and ipsilateral TMJ compressive stress (MPa), and the dependent variable mandible length (mm) showed a positive correlation (R2=0.52). Increased age and decreased TMJ compressive stress were non-linearly correlated with increased mandibular length.
Conclusions: Age and predicted TMJ compressive stresses were correlated with mandibular length.