A custom-fitted dental appliance having a base member with a generally U-shaped horizontal portion with opposing posterior sections and an anterior section disposed between the posterior sections. The base member has a vertical portion connected to a forward edge of the horizontal portion. The vertical portion has an arcuate curvature substantially following the curvature of the anterior section. The appliance includes over-molded molar pads that are bonded to the upper surfaces of the posterior sections of the base member. An over-molded anterior flange is bonded to the vertical portion of the base member. The molar pads and the anterior flange are formed from a thermoplastic material having a Vicat softening temperature below that of the base member. After heating the appliance to above the softening temperature of the over-molded portions, the molar pads and anterior flange may be custom fitted to the upper teeth and gums of the wearer.