A STUDY OF THE EFFECT OF HEAT ON DENTAL HARD TISSUE

열에 의한 치아경조직의 변화에 관한 연구

The purpose of this study was to examine the effect of heat generated by rotating bur on the dental hard tissue in vitro. Freshly extracted molar teeth with normal appearance from early 20's male were collected and experimental teeth were divided into 4 groups and the teeth in each group were prepared class I cavity with different clinical procedures as follows. The four methods were. I. 20,000rpm without coolant II. 20,000rpm with coolant III. 500,000rpm without coolant IV. 500,000rpm with coolant Five teeth were reserved intact as a control group. These teeth were longitudinally split into two parts by means of chisel after class I cavity preparation. In a control group 5 parts were boiled in water for 20 minutes and the other 5 specimens were not boiled. All specimens were immersed in 2% methylene blue dye solution and the image of dye penetration was examined and photographed under stereomicroscope. Followings were the results obtained through the study. 1. In control group, dye penetration of the unboiled specimens was increased than with the boiled group. 2. The specimens prepared cavity without coolant showed decreased dye penetration than with the coolant group. 3. 20,000rpm without coolant group showed the least dye penetration. 4. 500,000rpm with coolant group showed similar level of dye penetration to the unboiled specimens from the control group.