Although 80% of the splints made today are designed for the upper arch, periodontal therapy often demands the use of a full coverage lower splint to stabilize that arch. In fact, it is not uncommon for an upper and lower splint to be used at the same time, especially after orthodontic treatment has been completed in a periodontally compromised case. Note - To avoid unnecessary chair time adjusting an extra-coronal splint, always provide the lab with an accurate set of working casts and a construction bite that precisely represents the vertical and horizontal occlusal relationship of the splint.