Evaluation of the accuracy of coded healing abutments, scan body, and conventional impressions on implants with different angulations

Abstract

Purpose: To evaluate the effect of implant angulation on the accuracy (trueness and precision) of analog (ANA) and digital impressions using coded healing abutment (CHA) and scan body (SB), in implant-supported fixed partial dentures (ISFPDs).

Methods: Two mandibular models with internal connection implants were fabricated: one with parallel implants (M1) and another with angulated implants (M2). Three impression techniques were tested: CHA, SB, and conventional open-tray (ANA) (n=10 each). Digital impressions were acquired with an intraoral scanner, whereas conventional impressions were made with splinted open-tray copings and polyvinylsiloxane, then digitized with a laboratory scanner. STL files were imported into CAD software and analyzed with metrological software (Geomagic) to assess accuracy by comparison with coordinate measuring machine (CMM) reference data. Data were analyzed using one-way analysis of variance with Tukey’s HSD post hoc test, t-tests and Levene´s test.

Results: SB impressions showed the highest trueness for linear distance and implant positions. No differences were observed between CHA and SB for angulated implants. ANA exhibited greater deviations across most parameters. For precision, SB and CHA outperformed ANA, particularly in M2. Implant angulation reduced ANA accuracy but did not affect digital impressions.

Conclusions: Scan bodies provided the highest accuracy, especially in parallel implants. Coded healing abutments demonstrated acceptable accuracy across all variables and comparable performance to scan bodies in angulated implants, representing a viable alternative for digital impressions in ISFPDs.