Applied force during caries removal relating to operator and instrument

Objectives: The aim was to analyze the dentist's individual excavation procedure by recording the applied force on a rotating instrument tip. As polymer instruments are a gentle, less invasive method for carious dentin removal, it could be expected that the excavation procedure was different to carbide burs. Dentin autofluorescence (AF) and Knoop hardness number (KHN) were determined to evaluate qualitative differences of the cavity floors.

Methods: 28 extracted teeth were randomly assigned to two dentists and sectioned through the center of their lesion. Each specimen was mounted on an electronic scale. One half of each tooth was excavated with carbide round burs (C), the other with polymer burs (P). The vertically applied force was recorded continuously during excavation. AF was detected by confocal laser scanning microscopy. KHN was measured below the cavity floor. Means of force application were calculated for the beginning of the excavation procedure (first 10s, first half), and the whole excavation. The highest force values were registered. Results were analyzed statistically (t-test). Results:

Same small numbers indicate p<0.05.

In contrast to P, C showed differences between the operators concerning force application. Significantly less force application with C does not necessarily lead to lower KHN and more AF.

Conclusion: The force applied during excavation and the quality of the cavity floor after excavation were different in regard to operator and instrument type. Mounting of extracted teeth on an electronic scale seems to be a useful, objective method for the analysis of individual excavation procedures.

Supported by SS White Burs, Inc., Lakewood, NJ, USA.