This study reports a detailed two-dimensional analysis of tongue dimensions as well as assessment of adjacentsoft palate shape and upper airway structures without and with MAS treatment for OSA. Our finding suggests that MAS does induce changes in tongue shape. MAS treatment responders showed a greater decrease in tongue length (between the tongue tip and hyoid bone) with MAS in situ; whether differences in alteration of tongue position with MAS explain differences in treatment response requires further investigation.

Oral appliance (OA) can effectively treat obstructive sleep apnea; however, numerous types of oral appliances and designs are variable and the precise mechanisms behind differences in treatment outcomes are uncertain. The objective of this study was to evaluate the effects of different degrees of mandibular position [4° of bite openings (BO): 2, 4, 8 and 12 mm; and protrusion (P): 0, 50%, MAX], for both the upright and supine positions: BOP, BOP, BOP, BOP, BOP, BOP; with an OA on the: (1) activity of the genioglossus (GG) muscle by electromyogram, (2) inspiration by airflow sensor, and (3) recording mandibular movements (incisor and mandibular condyle point) in each position. Nine healthy male adults (age 27.5 ± 1.30 years) were recruited. The results show that GG muscle activity increased significantly from BO _P to BO_P during the supine position, and the strongest signal was found in BO_P, compared to all of the other positions, and GG muscle activity in BO_P tended to be lower. From supine to upright position the inspiration increased significantly but GG muscle activity did not. These results might be a stimulus to augment a compensatory mechanism of GG muscle induced by OA, however, mainly in protrusion position. The increase of BO (2-12 mm) and even maximum protrusion might not negatively affect the temporomandibular joint.

These results demonstrate that teeth autotransplantation can achieve a mastication efficiency and periodontal condition similar to normal teeth; however, without proper healing, the periodontal sensation of autotransplanted teeth may be inferior to that of normal teeth (<250).