The document summarizes Kennedy's classification system for dentition defects and Applegate's rules for evaluating them. It describes visualizing defects on plaster models, clinically, with x-rays, and schematically. It provides an algorithm for estimating defects, including determining the most distal defect, whether defects are endless or included, bilateral or unilateral, if included defects cross the midline, and modifications from other toothless areas.