Ji-Soo Lee1, Hye-In Choi2, Hyeonjong Lee3, Su-Jin Ahn4, Gunwoo Noh5. 1. Department of Dentistry, Graduate School, Kyung Hee University, Seoul, Korea. 2. Center for Bionics, Korea Institute of Science and Technology (KIST), Seoul, Korea. 3. Division of Fixed Prosthodontics and Biomaterials, Clinique of Universitaire Medicine Dentaire, University of Geneva, Geneva, Switzerland. 4. Department of Biomaterials & Prosthodontics, Kyung Hee University Hospital at Gangdong, School of Dentistry, Kyung Hee University, Seoul, Korea. 5. School of Mechanical Engineering, Kyungpook National University, Daegu, Korea.
Abstract
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.
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.