Dhari Alenezi

Date of Graduation

2018

Document Type

Thesis

Degree Type

MS

College

School of Dentistry

Department

Orthodontics

Committee Chair

Matthew S Bryington

Committee Co-Chair

Bryan D Dye

Committee Member

Elizabeth Kao

Abstract

Objectives: To evaluate the cutting efficiency, measured by rate, of tapered diamond burs with different grit sizes on sintered yttrium stabilized zirconia.;Methods: Seven types of tapered diamond burs with different grit sizes and with a 1.4 mm diameter were tested against sintered Yttrium stabilized zirconia blocks using an air-turbine handpiece and 0.9 N of cutting force. The burs utilized were: super coarse 181 microm, super coarse 150 microm, coarse 151 microm, coarse 125 microm, medium 107 microm, medium 100 microm and DuraCut 151 microm. Ten samples of each bur type were used. Depth of the cuts was measured by a Linear Variable Differential Transformer (LVDT) and data acquisition device. Each test was run for 5 minutes and divided into 3 time periods of 100 seconds each. A mixed-effect ANOVA test was completed for the effect of burs, time periods and combined effect of bur and time periods. A Tukey-Kramer HSD test was completed. Results of the study were compared to a previous study with parallel sided diamond burs using one-way ANOVA for the similar burs. P values were calculated to show significant differences.;Results: A significant difference was found among the burs and among time periods on cutting efficiency of 3Y-TZP. Coarse 151 microm super coarse 181 microm and DuraCut 151 microm were significantly more efficient in cutting 3Y-TZP in 5 minutes and in the first 100 seconds. Diamond burs with average grit size ≥ 151 demonstrated greater cutting efficiency. Within 5 minutes, the most efficient burs, coarse 151 microm, super coarse 181 and DuraCut 151 microm, had cutting depths of 4.35, 3.96 and 3.90 mm respectively. The cutting efficiency during the first 100 seconds was significantly greater for all burs. Comparison between tapered burs from this study and parallel burs from another study showed no significant difference in cutting efficiency between parallel sided and tapered shape diamond burs in cutting efficiency of diamond burs.;Conclusions: Diamond burs with an average grit size (≥151 microm) were the most efficient burs for cutting sintered 3Y-TZP within 5 minutes and in the first 100 seconds. Manufacturing process apparently plays an important role in improving cutting efficiency of diamond burs. All of the burs showed a significant decrease in cutting efficiency after 100 seconds. No difference was found between tapered diamond burs and parallel side burs. Cutting efficiency of diamond burs on 3Y-TZP is partially dependent on the coarseness of the bur.

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