Background: Replacement of diamond rotary instruments is critical for optimizing cutting efficiency. The authors aimed to assess and compare the cutting efficiency, surface roughness, and diameter of coarse-grit and medium-grit diamond rotary instruments after repeated cuts on indirect composite materials.
Methods: Medium-grit (115 μm) and coarse-grit (150 μm) diamond rotary instruments (NTI; Kahla GmbH) were tested on 2-mm-thick Ceramage (Shofu) (CM) and Lava Ultimate (3M ESPE) (LU) specimens and divided into 4 groups of 8 samples per group: LU-coarse, LU-medium, CM-coarse, and CM-medium. A high-speed handpiece with a cutting load of 0.9 N, speed of 400,000 rpm, and water flow rate of 25 mL/min was used. Cutting efficiency was assessed by measuring cutting time and surface roughness (roughness average) was measured using a surface analyzer and diameter was measured using calipers. Data were analyzed statistically using 2-way analysis of variance (ANOVA), followed by 1-way ANOVA with Tukey honestly significant difference post hoc test (P < .05). For comparison between cuts, 1-way repeated measures ANOVA was used for cutting time and surface roughness and paired samples t test was used for diameter (P < .05).
Results: Coarse-grit diamond rotary instruments had significantly higher (P < .05) cutting efficiency than medium-grit diamond rotary instruments at cut 1. At cut 10, significant differences (P < .05) in mean cutting time, surface roughness, and diameter were observed, with coarse-grit diamond rotary instruments having pronounced wear patterns compared with medium-grit diamond rotary instruments.
Conclusions: Differences in cutting time, surface roughness, and diameter after repeated cuts on indirect composite materials was instrument dependent. Coarse-grit rotary instruments had greater deterioration and wear than medium-grit rotary instruments.
Practical implications: Medium-grit diamond rotary instruments can be suggested for prolonged use (cut 10) on computer-aided designed and computer-aided manufactured composites. Diamond rotary instruments are recommended for replacement after cut 10 or 5 minutes of use on indirect composite materials.
扫码关注我们
求助内容:
应助结果提醒方式:
