Accuracy of an optical robotic computer-aided implant system and the trueness of virtual techniques for measuring robot accuracy evaluated with a coordinate measuring machine in vitro

Statement of problem

A unified standard for measuring robot implantation errors has not yet been established. A coordinate measuring machine (CMM) measures the coordinates of an object with high accuracy. However, evaluations of the accuracy of a robotic computer-assisted implant system (R-CAIS) using CMM are lacking.

Purpose

The purpose of this in vitro study was to evaluate the accuracy of an optics-based R-CAIS using a CMM and to assess the accuracy of cone beam computed tomography (CBCT), a laboratory scanner (LS), and an intraoral scanner (IOS) in measuring the accuracy of the R-CAIS.

Material and methods

Two 60×50×40-mm cubic models were prepared for the experiment. One master model and several replica models were used for the first part. Employing a robotic system software, virtual planning was performed on the digital imaging and communications in medicine (DICOM) image of the master model, and spatial mapping was performed by using an optical tracking marker (OT-marker) to ensure that virtual planning of the master model could be executed when replica casts were drilled and placed the implants. The actual placements of the implants in the replica casts were measured by using CMM. The errors between the actual and virtual-planned positions were calculated. In the second part, virtual planning was performed on the experimental model, and an optics-based R-CAIS was used to drill holes and place the implants. The actual positions of the implants were measured by using CMM, CBCT, LS, and IOS. The errors between the actual and virtual-planned positions were calculated, and the error results among groups were compared by 1-way analysis of variance or a nonparametric test. The Dunnett test was used for post hoc comparison (α=.05).

Results

In the first part, the entry, apical, and angle deviations were 0.33 ±0.10 mm, 0.41 ±0.11 mm, and 0.33 ±0.13 degrees, respectively. In the second part, as compared with CMM, no statistically significant differences were observed in the LS group (P>.05), whereas significant differences were observed in entry-depth, entry, apical-depth, apical, and angle deviations in the IOS group, as well as in entry-depth and apical-depth deviations in the CBCT group (all P<.05).

Conclusions

The optical-based R-CAIS exhibited high accuracy. The application of CBCT for clinical implantation may be close to that of the true deviation.