Schedule 2 [P-6] Change in the retentive force of Akers clasp for CAD/CAM hybrid resin crowns by repetitive insertion and removal test *KEITA TOMONO1, YUTO KATO1, WADACHI JURO1, KATO YOSHIMITSU1, TASAKA AKINORI1, YAMASHITA SHUITIRO1 (1. Department of Removable Partial Prosthodontics, Tokyo Dental College)