Comparative accuracy study of three extraoral photogrammetry methods, one intraoral photogrammetry system, and a...

The accuracy of implant scans is contingent upon the scanning technique selected. The accuracy of complete arch implant scans using different techniques, including intraoral and extraoral photogrammetry methods (PGs) and noncalibrated implant scan bodies (ISBs) oriented toward the center of the arch, requires further evaluation.

The purpose of this in vitro study was to evaluate the accuracy of complete arch implant scans captured using 3 extraoral PGs, 1 intraoral PG, and 1 noncalibrated ISB system.

An edentulous stone cast with 6 implant abutment analogs and a laboratory scan (T710) for the control scan were obtained. Five groups were created based on the technique used to capture complete arch implant scans: 3 extraoral PG systems, Grammee (Grammee group), MicronMapper with screw-retained markers (MM-Screw group), and MicronMapper with snap-on markers (MM-Snap group), an intraoral PG (Elite group), and a noncalibrated ISB system (IOConnect group) (n=15). In the 3 extraoral PG groups, the corresponding markers were placed on the implant abutments of the reference cast, followed by the recording of consecutive implant scans with the specific camera of each system. In the Elite group, the ISBs were placed on the implant abutments of the reference cast, and scans were captured using the explicit intraoral scanner (IOS) (Aoralscan Elite). In the IOConnect group, the noncalibrated ISBs were placed on the implant abutments toward the center of the arch. Then, IOS scans were captured using an IOS (TRIOS 5). Euclidean linear and angular measurements were calculated for the 6 implants. The measurements obtained in the reference scan were used to calculate the scanning discrepancies with each experimental scan. One-way ANOVA and Tukey post hoc tests were used to analyze trueness. The Levene test was used to analyze precision (α=.05).

Linear (P<.001) and angular (P=.012) trueness discrepancies were found among the groups tested. The Grammee and Elite groups had the best linear trueness, while the IOConnect group obtained the worst linear trueness. The overall mean linear trueness values measured among the groups ranged from 21 to 78 µm. Additionally, the Grammee and Elite groups had the best angular trueness, while the MM-Snap group obtained the worst angular trueness. The overall mean angular trueness values measured among the groups ranged from 0.124 to 0.511 degrees. Moreover, the Levene test demonstrated significant angular precision discrepancies among the groups tested (P=.012). The Elite group had the best angular precision, while the MM-Screw had the worst angular precision.

The implant scanning technique affected the accuracy of complete arch scans. Accuracy discrepancies were measured for the techniques tested; however, all provided a clinically acceptable method of capturing implant positions.