Does 2 years' nocturnal treatment with a mandibular advancement splint in adult patients with snoring and OSAS cause a change in the posture of the mandible?

The aim of this pilot study was to investigate the effects of 2 years' nocturnal treatment with a mandibular advancement sprint in adult patients with snoring and obstructive sleep apnea syndrome with respect to possible development of a forward position of the mandible or other dentofacial changes. Thirty snoring and sleep apnea patients, mean age 55.3 years (SD, 8.61; range, 46.5 to 79.8 years), referred from the Ear, Nose, and Throat Department, were treated with an acrylic splint with full tooth coverage that advanced the mandible 5 to 8 mm (70% of maximal protrusion) and used 5 mm opening vertically. The splint was used 6 to 8 hours per night and 5 to 7 nights per week. Two lateral head radiographs were taken in centric occlusion, 1 before and 1 after 2 years of treatment. A small but statistically significant forward and downward change in mandibular position was found after treatment; mean was 0.4 mm (SD, 0.53; range, 0.0 to 2.0 mm; P < .001) and 0.3 mm (SD, 0.43; range, 0.0 to 1.5 mm; P < .001), respectively. The forward and downward movement of the mandible was accomplished by a statistically significant increase in mandibular length-mean was 0.4 mm (SD, 0.62; range, 0.0 to 2.5 mm; P < .01)-and a significant decrease in overjet (P < .001) and overbite (P < .05). However, none of the patients reported any permanent sense of altered occlusion, and the anteroposterior distance between habitual occlusion (intercuspal position) and centric relation (retruded position) did not exceed 1.0 mm in any of the patients either before or after the treatment. The change in mandibular position might be a result of a condylar and/or glenoid fossa remodeling or condylar position changes within the fossa as a compensatory reaction to the advancement of the mandible (bite jumping). However, to visualize and analyze such possible changes in detail, additional studies using lateral tomography of the temporomandibular joints or magnetic resonance imaging are required. Furthermore, because the treatment of snoring and OSAS patients is considered to be lifelong, long-term studies are needed to analyze if the small change in mandibular position will continue with further treatment.