Effect of Multiple Use of Impression Copings and Scanbodies on Implant Cast Accuracy

Purpose: There are currently no clear guidelines on the reuse of metal implant impression copings and scanbodies in implant dentistry. Manufacturers generally recommend single use, which has cost and ecologic implications. The objectives of this study were to examine the effect of multiple use of implant impression copings and scanbodies on the accuracy of partially dentate implant casts. Materials and Methods: Ten direct polyether impressions were made of a partially dentate mandibular acrylic resin master model fitted with two internal connection implants (Straumann RC bone level) in the positions of right first premolar and molar, to produce 10 dental stone casts. A single set of impression copings was utilized for the 10 impressions. The sample casts and the master model were digitized using a laboratory scanner. Ten digital scans were then performed on an implant stone cast with two bone-level internal connection implant analogs using one set of scanbodies to produce scans 1 to 10. Measurements were made on all the digitized casts using computer software and discrepancies calculated in the x-, y-, and z-axes, and in the overall three-dimensional position (R). Data were statistically analyzed using paired t tests (α = .05), and P values were adjusted using Holm- Bonferroni sequential correction. Results: The outcomes were mixed, in that no significant differences were found between the casts or scans produced by reusing impression copings (P > .05) and scanbodies (P > .005), respectively, in all dimensions, for most repetition cycles; however, significant differences were noted in the y-axis for cast 6, and in relation to R, for casts 2, 4 (P .05), and 8 (P .005), and the scanbody reuse elicited significant differences in 3D(R) with scan 2 alone (P .005). Conclusion: Reuse of impression copings and scanbodies up to 10 times did not seem to consistently affect the accuracy of partially dentate multi-implant dental casts and digital models. Keywords: CAD/CAM, dental implant, dental impression technique, dental models, digital scans, impression accuracy, reuse, scanbodies