Biomechanical effect of mandibular advancement device with different protrusion positions for treatment of obstructive sleep apnoea on tooth and facial bone: A finite element study

Background The mandibular advancement device (MAD) is widely used for obstructive sleep apnoea (OSA) treatment, and several studies have demonstrated its effectiveness. However, no comprehensive studies have yet examined the biomechanical safety of the MAD. Objectives The objective of this study was to analyse the biomechanical effect of different protrusion positions of a MAD on the teeth and facial bones. Methods The posterior restorative forces due to the stretched mandibular muscles were measured by pressure sensors attached to the experimental mandibular advancement device for mandibular protrusions of 10-70% of the maximum protrusion of the subject. A detailed three-dimensional biomechanical model of the study subject, constructed from computed tomography scans, was used in finite element analysis, with loading conditions calculated from the measured posterior restorative forces. The outcome measures were the principal stresses on the periodontal ligaments (PDL) and cancellous bone, and the pressure at the PDL surfaces. The measurements were used to analyse the risk of the tooth movement, tooth root resorption, and bone resorption. Results The lowest and highest restorative forces occurred at 40% and 70% of maximum protrusion, respectively. The highest risk of tooth movement occurred at the mandibular molar teeth. The mandibular second molar teeth had the highest risks of root and bone resorption. Conclusions Mandibular advancement at 70% of maximum protrusion induces risks of tooth root resorption and bone resorption. The mandibular second molars were subjected to the highest stresses. Stress on the teeth and facial bones was the lowest at 40% of maximum mandibular advancement.