Abstract: This invention relates to the field of 3D printing used to make a dental aligner for the purpose of straightening teeth or a mouthguard for the purpose of protecting teeth. The appliance is a hard polymer layer that encases the upper, lower or both sets of teeth to exert correcting forces on the teeth to realign their position, optionally these clear aligners can also incorporate a wire for more rapid treatment. This invention describes a method of directly 3D printing the aligner or mouthguard from liquid photopolymer rather than as it is currently manufactured by thermoforming plastic over a custom model and then trimming it to the desired size.