Comparison of cutting efficiency of dentated burs

Dentated (crosscut) burs have been proposed as a means to improve the effectiveness in cutting preparations. Objectives: to compare the cutting performance of highly (H.D.) and standard dentated (S.D.) burs. Methods: groups were divided as: SS White Burs – standard- S.D. (A) and Great White- H.D. (B); Dentsply Midwest standard-S.D. (C) and Multiprep-H.D. (D) and Brasseler – standard-S.D. (E). Using an electric handpiece running at 200,000 RPM controlled by a computerized robotic testing device, standard shaped burs (#557) randomized for run order (n=30; 6 subgroups of 5 samples). skim cut to a depth of 0.375” (1/2 diameter of the bur), into a 3.0”x1.0”x0.5” glass-ceramic block (Macor). A standardized load of 150g was applied while cooling with a water flow rate of 80 ml/min. The handpiece was calibrated for orientation, speed, torque, coolant spray, force of preparation and concentricity of burs during testing. Data was collected for the time required (in seconds) for the depth of each cut and divided in subgroups accordingly to the first (1), second (2) and third (3) cut with each bur. Statistical analysis was conducted with ANOVA followed by a post hoc Scheffe test. Results: cutting efficiency (in sec., mean+SD): A1=3.58+.64; A2=2.84+.30; A3=3.33+.35; B1=3.07+.58; B2=2.42+.39; B3=2.85+.48; C1=3.89+.54; C2=3.11+.38; C3=3.69+.49; D1=3.64+1.37; D2=3.11+1.97; D3=4.04+4.68; E1=3.55+.60; E2=2.89+.40; E3=3.43+.49. Conclusion: There was a statistically significant difference in the cutting efficiency of a highly dentated bur (SS White - Great White) at the second cut compared to the other burs and cuts (p=0.001). For all burs tested - albeit not significant- the second cut was always more efficient when compared to the first and third cuts.