Influence of planning software and template design on the accuracy of static computer assisted implant surgery performed using guides fabricated with material extrusion technology: An in vitro study

Abstract

Objectives: This in vitro study aimed to assess the influence of the planning software and design of the surgical template on both trueness and precision of static computer assisted implant surgery (sCAIS) performed using guides fabricated using material extrusion (ME).

Methods: Three-dimensional radiographic and surface scans of a typodont were aligned using two planning software (coDiagnostiX, CDX; ImplantStudio, IST) to virtually position the two adjacent oral implants. Thereafter, surgical guides were fabricated with either an original (O) or modified (M) design with reduced occlusal support and were sterilized. Forty surgical guides were used to install 80 implants equally distributed amongst four groups: CDX-O, CDX-M, IST-O, and IST-M. Thereafter, the scan bodies were adapted to the implants and digitized. Finally, inspection software was used to assess discrepancies between the planned and final positions at the implant shoulder and main axis level. Multilevel mixed-effects generalised linear models were used for statistical analyses (p = 0.05).

Results: In terms of trueness, the largest average vertical deviations (0.29 ± 0.07 mm) were be assessed for CDX-M. Overall, vertical errors were dependant on the design (O < M; p ≤ 0.001). Furthermore, in horizontal direction, the largest mean discrepancy was 0.32 ± 0.09 mm (IST-O) and 0.31 ± 0.13 mm (CDX-M). CDX-O was superior compared to IST-O (p = 0.003) regarding horizontal trueness. The average deviations regarding the main implant axis ranged between 1.36 ± 0.41° (CDX-O) and 2.63 ± 0.87° (CDX-M). In terms of precision, mean standard deviation intervals of ≤ 0.12 mm (IST-O and -M) and ≤ 1.09° (CDX-M) were calculated.

Conclusions: Implant installation with clinically acceptable deviations is possible with ME surgical guides. Both evaluated variables affected trueness and precision with negligible differences.

Clinical significance: The planning system and design influenced the accuracy of implant installation using ME-based surgical guides. Nevertheless, discrepancies were ≤ 0.32 mm and ≤ 2.63°, which may be considered within the range of clinical acceptance. ME should be further investigated as an alternative to the more expensive and time-consuming 3D printing technologies.

Keywords: Additive manufacturing; Biopolymers; Computer-assisted surgery; Material extrusion; Static computer assisted implant surgery; Surgical guide.