A Clinical Comparison of Digital and Conventional Impression Techniques Regarding Finish Line Locations and Impression Time Publisher Pubmed



Koulivand S¹ ; Ghodsi S² ; Siadat H² ; Alikhasi M²
Source: Journal of Esthetic and Restorative Dentistry Published:2020

Abstract

Objective: This study compared digital and conventional impression techniques regarding impression time, frequency of adjustments, and adaptation of cobalt-chromium (Co-Cr) copings with supragingival and subgingival finish lines. Materials and Methods: Thirty premolars prepared for single-unit metal-ceramic restorations with supragingival and subgingival finish lines (n = 15). Conventional impression and digital scan of prepared teeth were made. Using computer aided design/computer aided manufacturing (CAD/CAM) system the copings were produced by a milling machine from Co-Cr blocks and internal and marginal discrepancies were measured using silicone replica technique. Data were analyzed using repeated measures ANOVA and Mann-Whitney test (alpha =.05). Results: The impression technique had a significant effect on the magnitude of gap (P <.001). The internal and marginal gaps in the digital technique (49.43 μ and 60.07 μ, respectively) were significantly lower than the values in the conventional method (91.88 μ and 96.96 μ, respectively—P <.001). Finish line positions had no significant effect on the fit and marginal gap of copings (P =.54 and.243, respectively). The mean impression time (19′:27″ in conventional technique and 10′:31″ in digital technique) was significantly shorter (P <.001) and the mean frequency of adjustments (2.2 times for conventional and 1.3 times for digital technique) was significantly lower in the digital technique (P <.001). The gingival biotype (thick or thin) had no significant effect on marginal and internal fit (P =.052 and.319, respectively). Conclusion: The digital technique was superior in terms of fit, impression time, and frequency of adjustments. Finish line positions had no significant effect on the fit of copings. Clinical Significance: Using intraoral scanner promotes the fits of restorations in supragingival and subgingival finish lines. © 2019 Wiley Periodicals, Inc.