Accuracy of digital tooth preparations recorded using the plaster model scanning technique and two silicone impression scanning techniques.

Objective: To compare the accuracy of digital tooth preparations recorded using the plaster model scanning technique and two silicone impression scanning techniques.

Materials And Methods: A maxillary resin model with incisor and first molar abutment preparations was used as the experimental model and scanned to serve as the gold standard. Three groups of digital models were generated, with 10 models in each group. Group 1 comprised 10 silicone impressions of the experimental model and were scanned using the 3Shape Trios3 intraoral scanner. Group 2 comprised 10 impressions covered with a scanning spray and scanned using the 3Shape D2000 extraoral scanner. Group 3 comprised plaster models made from the 10 impressions and scanned using the 3Shape D2000 extraoral scanner. Root mean square values were obtained by comparing the scanning data of each group with the gold standard using the Geomagic software. The one-way analysis of variance and paired student's -tests were used to analyse the root mean squares; the significance level was set at 0.05.

Results: No statistically significant difference was observed in the root mean squares of the non-prepared teeth among the three groups (P = 0.12). The mean root mean squares of Groups 1, 2, and 3 were 0.11 ± 0.03 mm, 0.07 ± 0.03 mm, and 0.10 ± 0.05 mm, respectively. A statistical difference was observed in the incisor area among the three groups (P < 0.05), wherein Group 2 showed the lowest root mean square value (0.06 ± 0.02 mm). No significant difference was observed in the first molar area among the three groups (P = 0.142).

Conclusions: Digital tooth preparations models obtained from silicone impressions by extraoral scanning showed similar accuracy to intraoral scanning and plaster model scanning. This indicates that the clinical workflow of taking silicone impressions and scanning with an extraoral scanner is an acceptable and convenient choice.