A mouth guard composed of a polymer consisting essentially of polycaprolactone exhibits a low softening point, enabling it to be easily custom-fitted by the user or a health professional. The material is provided in the form of a generally U-shaped, unformed sheet of material, enabling the material to be heated with hot water or microwave energy and custom-fitted to the dentition of a user. The mouth guard may be perforated and may include a no-stick layer and/or a flavoring agent. A plurality of mouth guards may be provided in different sizes for children and adults and different shapes for different sports. In the preferred embodiments the mouth guard has a periphery including a plurality of lobes and cusps to enhance fitting. A method of fabricating an improved mouth guard according to the invention is also disclosed.