Biomechanical effects of a mandibular advancement device on the periodontal ligament: Based on different bone models.

Obstructive sleep apnea syndrome (OSAS) is recurrent apnoea caused by upper airway obstruction during sleep. In severe cases, OSAS might lead to sudden death. Currently, the mandibular advancement device (MAD) is the preferred product for the treatment of mild to moderate OSAS because of its compliance, portability and low cost. However, many clinical studies have suggested that long-term use of MAD might cause occlusal changes, periodontitis, muscle soreness, and joint damage. In view of the difficulties in the measurement of relevant mechanical factors in vivo, the present work aimed to quantitatively analyze biomechanical mechanisms that might lead to these side effects through computer numerical simulations and a nonhomogeneous alveolar bone model was established to approximate the actual bony features of the jaw in the simulations model. First, a 3D digital model of the teeth, periodontal ligament(PDL), and alveolar bone was created on the basis of computed tomography images and assembled with a 3D model of the MAD. A nonhomogeneous alveolar bone model was created based on computed tomographic images, and the stresses acting on the PDL were computed using the finite element method. The results showed that the nonhomogeneous model could more realistically reflect the mechanical properties of the alveolar bone and obtain the true stresses compared with the homogeneous model, which underestimated the adverse effects of PDL therapy. The numerical simulations in this paper can help doctors make more accurate judgements about MAD treatment from an oral health protection perspective.