Learning curve of digital intraoral optical scanning for complete arch: an in vitro study

OBJECTIVE: To evaluate the learning curve by unskilled operator for a complete arch digital impression in terms of scanning time and accuracy. MATERIALS AND METHODS: Three unskilled operators (OP1, OP2, and OP3) were enrolled to scan for 15 times each one an edentulous maxillary polymethylmethacrylate (PMMA) milled model with six implant analogs in different angulation and depth. The scanning times were recorded for each scan of the randomized sequence. The resulting 45 test files were aligned by the reference one, obtained by a high-precision industrial scanner. Each test file was processed with dedicated software to assess the linear (DX, DY, and DZ axis) deviations, that were summed up to obtain an average value of three-dimensional deviation. RESULTS: The three operators showed a mean scan time of 169.6 seconds (s), 217,9 s, 193,7 s respectively. Each operators show a statistically significant scan time reduction from the first to last scan: OP1 p=0,001; OP2 p=0,008; OP3 p=0,003. The average three-dimensional (3D) errors reported were OP1 133 microns (mm), OP2 111 mm and OP3 107 mm. Regarding the accuracy, a statistically significant reduction in the average 3D error was reported: OP1 p = 0.02; OP2 p = 0.04; OP3 p = 0.04. CONCLUSION: Within the limitation of this in vitro study, it seems to be that the repetitive use of IOS significatively affects the investigated variables in an overall scanning time reduction and scan accuracy enhancement.