An oral appliance includes a reinforcing member or splint embedded within a polymer shell. The reinforcing member or splint includes an anterior portion embedded within an anterior wall of the polymeric shell, a posterior portion embedded within a posterior wall of the polymeric shell, and a transverse portion embedded within a transverse plate of the polymeric shell. The reinforcing member or splint is operative for preventing movement of the user's dentition over time when wearing the oral appliance.
