A study on the grinding accuracy of a copy milling machine for dental use

In order to assess the relationship between the profiling pressure of a copy milling machine for dental use and the accuracy of the dimensions of the objects produced, a Celay System was used to profile a metal-cylinder model, and its dimensions were compared with the workpieces. The results showed that, when a cylindrical model with a diameter of 6 mm was subjected to freehand profiling, the mean processing error of the object produced was -0.026 mm, and the profiling pressure was 4.6 gf to 131.7 gf (mean: 76.6 gf). However, the fluctuations in profiling pressure decreased by 1/5 during profiling operations when accessories that fixed the profiling pressure and the profiling loci were used. Moreover, while the processing error when the model was profiled at a profiling pressure of 76 gf or less was a mere 0.005 mm, at 110 gf it rose to 0.022 mm. Based on the above, the processing error that occurred as a result of profiling pressure appeared to affect processing accuracy. On the basis of these findings, profiling as light weight must be performed with as possible in order to obtain accurate products using the copy milling machine for dental use, and the results suggested the necessity of attaching control devices to the copy milling machine to make accurate restorations.