Accuracy of SmartShape Healers Compared to Conventional and Digital Workflows

Statement of Problem: Smart shape healers/coded healing abutments have been emerging however, not enough studies about their accuracy are still limited.

Objective: Investigate the accuracy of smart shape healers for final impressions of a 3-unit implant-supported prosthesis.

Materials and methods: In-vitro study where a partially edentulous mandibular stone model with 2 implants was prepared as the master model. Three groups were con-sidered for each group; 12 impressions were prepared, then 3 impressions were selected based on digital analysis for fabrication of 3 corresponding verification bars. The first study group involved conventional impressions using open-tray impression copings (OTG), and the second group, titanium scan bodies (TSB) were placed. For the final study group, SmartShape Healers (SSH) were used. For the second and third groups, an intraoral scanning (IOS) impression technique was done. After bar fabrication, two experienced clinicians blindly assessed the fit of each bar on the master model through visual inspection, assessment of periapical radiographs, screw-resistance test, and under a microscope.

For the significant testing among the three groups, a binary/non-parametric Kappa coefficient, Bowker’s tests were used. As for the parametric data, a one-way analysis of variance (ANOVA) test was followed by a Tukey post-hoc. JMP Statistical Discovery (ver. 18.2.1, JMP Statistical Discovery LLC, 920 SAS Campus Drive, Cary, NC 27513) was utilized to assess contingency and statistical analysis for the accuracy of fit assessment between different impression techniques.

Results: For both visual assessment and radiographic inspection, a statistically significant difference was observed for inter-examiner agreement by Kappa coefficient result of 0.73 and a non-significant result for Bowker’s test. Keyence measurements allowed parametric results, a one-way analysis of variance (ANOVA) test was run by sample, retainer number, surface, and impression technique. Significant results, P<0.05, were found for sample, retainer, surfaces on #30, and impression techniques. Non-significant results P>0.05 were found between surfaces around implant #28.

Conclusion: Results have shown differences between impression techniques. Multiple methods must always be used to confirm fit, as relying only on one method can be mis-leading. SSHs have been shown to have a higher probability of a bigger vertical gap compared to OTG and TSB.