Digital Upper Overlay Hard Splint for 3D Printing Digital overlay hard splint for the upper jaw, that designed to create a newly improved bite overlaying the patients poorly biting teeth. Many people find that from wearing the splint and even after just two or three adjustments the pain or clicking of the jaw has gone. Overlay hard splint is designed in 3Shape Appliance Designer 2013 and realistically rendered in KeyShot Pro 5.2.