Stress distribution in the temporomandibular joint after mandibular protraction: A three-dimensional finite element study

Objective: To evaluate the stress patterns in temporomandibular joint (TMJ) during mandibular protraction at different horizontal advancements with constant vertical height in a construction bite using a three-dimensional finite element method. Materials and Methods: A three-dimensional computer-aided model was developed from the magnetic resonance imaging (MRI) of a growing boy (age 12 years) using MIMICS software (version 7.0, Materialise, Leuven, Belgium). Stresses with constant vertical opening of 5 mm changing the sagittal advancements from 0 mm to 5 mm and 7.5 mm were recorded. Differences in magnitude and pattern of stresses were compared. Results: The tensile stresses in the posterosuperior aspect of the condylar head and on the posterior aspect of the glenoid fossa migrated posteriorly with increased bite advancements. The location of tensile stresses changed in the condylar head and fossa on mandibular protraction of 5 mm to 7 mm. Conclusion: This study indicates that larger horizontal advancements of construction bites may not be favorable for tissues of TMJ. Clinical application necessitates study on an animal model.