Biomechanical effects of a mandibular advancement device on the temporomandibular joint

Purpose: Mandibular advancement devices are commonly used in the treatment of patients with mild to moderate obstructive sleep apnea (OSA). Designed to maintain the mandible in forced protrusion while being worn, mandibular advancement devices (MADs) are intended to increase the upper airway during sleep, thereby reducing OSA symptoms. Depending on the extent of mandibular protrusion, side effects including temporomandibular joint dysfunction are frequently reported. These are likely to reduce overall treatment success by affecting therapeutic adherence.
Material and methods: To investigate the biomechanical effects of an MAD on the temporomandibular joints, we used a biomechanical model of the human masticatory system. Alterations to the model were applied to mimic the effects of a titratable duoblock MAD. The extent of mandibular protrusion was simulated up to 10 mm in steps of 1 mm. Compression and shear stresses on the temporomandibular structures were predicted during an open–close maneuver and in neutral position.
Results: As the extent of mandibular advancement increased, the mandibular condyle migrated anteriorly until passing the articular tubercle. Stress on the temporomandibular joint structures did not considerably increase in rest whatever the extent of mandibular advancement. However, closure of the jaw required extra muscle force as mandibular advancement increased.
Conclusion: Results from this study suggest that temporomandibular dysfunction following MAD wearing might be related to altered muscle dynamics rather than changes due to increased stress in the temporomandibular joint itself.