The Chairside Instructor 31 Effects of Tooth Loss Tooth Replacement Position of teeth immediately after a tooth is lost. If the tooth is not replaced, other teeth can drift out of position and change the bite. Facial Collapse Drifting Teeth Also, the mouth loses some of its shape, and the lip line straightens. Pouches become pronounced on either side of the lower jaw. Cracks and sores may form at the corners of the mouth. When teeth are lost and not replaced, the face looks older. The lips appear thin and flattened. The chin moves forward and upward and appears pointed. Without tooth replacement With tooth replacement Without tooth replacement With tooth replacement