Comparison of Cutting Efficiency on CAD/CAM Resin Blocks

Objectives: The objective of this study was to investigate the cutting efficiency of diamond burs on CAD/CAM resin blocks with an electric handpiece.
Methods: Four different types of CAD/CAM resin blocks namely, Cerasmart 270 (C270, GC Dental Products), Cerasmart 300 (C300, GC Dental Products), KZR-CAD block 3 (KCB3, Yamakin) and Shofu Block HC Hard (SBH, Shofu) were tested. The blocks were sectioned with a low-speed cutting machine to make 80 specimens, each 3 mm in thickness (n=10). The experimental apparatus with the electric handpiece was used at a set speed of 200,000 rpm, was used for the cutting test. The rotational speed of the electric handpiece is controlled to be constant by the feedback function. The load during cutting was 50, 100, 150, 200 g, and the cutting time was 5 seconds. After the cutting test, the length of the cutting trace under each condition was measured and the average value was calculated. Then, the cut surface of the blocks were observed by SEM. Data were analyzed statistically by a one-way ANOVA followed by Tukey’s Honestly Significant Difference (HSD) test (α= .05).
Results: The average length of cutting trace in each load condition was summarized in the table.
In all types of blocks, the amount of cutting increased in proportion to the increase in cutting load. There was no significant difference among the average value of C270, C300 and KCB in every load condition. The average value of SBH is significant higher than that of other three blocks in every load condition.
Conclusions: SBH showed significantly higher machinability among the four resin blocks used this experiment.