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D. GEKELMAN1, A. YAMAMOTO1, G. NOVAK2, M.G. OTO1, and J.M. WHITE1, 1University of California San Francisco, USA, 2Dentsply Midwest, Des Plaines, IL, USA Objective : the purpose of this study was to measure in vitro the temperature rise produced by dental cutting with air-turbine handpieces. Methods: six air-turbine handpieces with different coolant specification were used: Midwest XGT (XGT), BienAir (BA), Star (ST), Kavo 635B (K1), Kavo 649B (K2) and Siemens (SI); with 2 cutting instruments, diamond (D) and carbide (C); and under 3 parameters of air/water coolant, minimum (MN), medium (MU) and maximum (MX), varying the water flow rate (5-20 psi), water pressure (5-10 psi), chip air pressure (5-15 psi) and drive air pressure (30 psi). The teeth, extracted human molars, were positioned on a standardized cutting station and axial cuts (n=144) were performed for 15 s, 4 repetitions each, with independent variables of handpieces (n=24 cuts for each), burs (n=72 cuts for each), under 3 specific air/water flow settings (n=24 cuts for each). An infra-red camera was used to record the dependent variable of temperature rise on the tooth surface produced by the dental cutting, with a speed of 1 scan every 45 ms. A two-factor ANOVA was used for statistical analysis (p≤0.05). Results:
Means Table for Temperature (oC) ± 1 SD
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MN |
MU |
MX |
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D |
16.8 (±13.7) |
6.8 (± 5.9) |
4.0 (±2.9) |
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C |
13.6 (±13.1) |
5.0 (± 4.9) |
2.7 (±3.9) |
There was a significant effect of coolant on surface temperature rise for D where MX<MU<MN, and for C where MX=MU<MN.The effect of handpiece on surface temperature rise for D burs was XGT=ST=BA<K1=K2=SI. And for C burs: XGT=ST=BA<K1=K2<SI. Conclusions: handpiece design specifications affect dental surface temperature as a function of cutting instrument and air/water parameters. Supported by Dentsply Midwest.
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