Semester

Spring

Date of Graduation

2010

Document Type

Thesis

Degree Type

MS

College

School of Dentistry

Department

Periodontics

Committee Chair

Mark W Richards

Abstract

Repeated use of implant drills progressively increases their wear and decreases their efficiency, thus producing more frictional heat. Multiple factors have been linked to heat production during surgery including drill sharpness. The purpose of this research is to focus on the heat generated by an implant drill and how the wear factor and the material of the drill effect the heat generated by that drill when drilling through bone.;Two implant drill Systems were evaluated in vitro using bovine back rib bones. Two implant drill system were used. System A was stainless steel surgical drills sizes 2.3, 2.8 and 3.4 mmD (Tapered Screw-Vent surgical drills by Zimmer Dental). System B was alumina-toughened zirconia ceramic surgical drills Sizes were 2.0, 2.8 and 3.5mmD (Thommen Medical). Transverse sections of the bovine bone were obtained. Using a template, one canal 10mm long was drilled for the thermocouple. Two marks using a sharp pencil were made next to the thermocouple canal and 0.5 mm away from the largest final size drill at each site. Sterilization before the first use and after each osteotomy was preformed. Sequential drilling was performed at speed of 1500 Rpm and external irrigation 40ml saline per min was used. The maximum temperatures were recorded for all the three drills used for the system A and B while maintaining a constant weight of 2.4 kg applied to the hand piece while drilling. After each trial the drills were sterilized and the preparation repeated twenty five times for each system. All the ostetomies were performed by the same clinician to simulate a real clinical setting situation. Both implant drills system were scanned using Scanning Electron Microscopy before the first and after the last use to evaluate visual wear.;The study showed no significant difference between the two systems from material stand point. Both systems A and B showed an increase in temperature as the drill wear out. It was also found that significant wear occurred to both systems after twenty five usages. The maximum temperature for system A was 31.3°C and for system B was 31.2°C. SEM taking before start and at the end of the study showed significant wear to both systems. Chips and cracking at the drills edges explained the increase in temperature as the drills wears. From this limited in-vitro study, it appears that Implant multiuse drills can be used for a maximum of 25 times without resulting in bone temperature that is harmful.

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