VARIATIONS AMONG OPERATORS IN THE PERFORMANCE OF TUNNEL PREPARATIONS IN-VITRO

A study was performed to assess the variations among dentists in the p erformance of tunnel preparations for ''caries'' removal and cavity de sign, and to evaluate how these variations are affected by instruction and training. Twenty-seven dentists with limited clinical experience in performing tunnel preparations participated in the study. They did three partial tunnel preparations each in extracted premolars with sta ndardized, artificial, approximal ''carious lesions''. The first prepa ration was made without instruction, the second after instruction and under supervision, and the last without supervision. After information /supervision, 26% did not manage to do a tunnel preparation without re sidual caries, indicating that this is not an easy procedure for begin ners. The occlusal opening was significantly larger and the width of t he remaining approximal wall was significantly smaller in preparations without ''residual caries'' than in those exhibiting ''residual carie s''. Visibility appears to be improved by extending the occlusal openi ng toward the marginal ridge.