Figure 2.

Three types of one-piece mandibular advancement devices (MADs) used in this study. They were made of different materials and compositions; however, the overall configuration and thickness of the device was controlled. (A) Model 1, a single-layer MAD (thickness 4 mm, PETG); (B) model 2, a double-layer MAD (thickness 4 mm, outer: PETG/ inner: TPU); (C) model 3, a triple-layer MAD (thickness 4–4.5 mm, inner: reinforced resin core/ middle: TPU/ outer: PETG); (D) resin core area in model 3. PETG, polyethylene terephthalate glycol; TPU, thermoplastic polyurethane; Mx, maxilla; Mn, mandible.