TOOTH STRUCTURE LOSS APICAL TO PREPARATIONS FOR FIXED PARTIAL DENTURES WHEN USING SELF-LIMITING BURS

Statement of problem. Burs with guide pins may be used to limit the de pth of tooth preparation for fixed partial dentures. The effects of gu ide pins on tooth structure apical to the finish line after tooth prep aration for fixed partial dentures has not been recorded. Purpose. Thi s in vitro study recorded loss of tooth structure within 1.0 mm apical to the finish line of teeth prepared with straight cylinder and taper ed cylinder self-limiting burs and one conventional bur. Material and methods. Forty-five extracted human teeth were randomly divided into t hree groups. The facial surface of each tooth was prepared with two ty pes of diamond burs with guide pins and a conventional diamond for the control. The surface was profiled before and after tooth preparation. Profiled surfaces were analyzed and the groups were compared using an alysis of variance and the Tukey-Kramer HSD test (alpha a = 0.05). Res ults. No significant difference was recorded between the control group and the group prepared with a round-ended tapered cylinder self-limit ing pin. However, there was a statistically significant difference bet ween the control and cylindrical pin groups, and between the two group s prepared with self-limiting diamonds. Conclusion. This study reveale d abrasion apical to the finish line of the preparation in all groups. The cylindrical guide pin group exhibited the greatest loss of tooth surface.