In vitro comparison of fit accuracy assessment methods for removable partial dentures: Application across analogue, hybrid, and digital workflows

Objectives: To evaluate the fit accuracy of removable partial denture (RPD) frameworks fabricated using analogue, hybrid, and digital workflows, and to compare discrepancies between anterior and posterior palatal regions. Methods: Twenty-one cobalt-chromium RPD frameworks (n = 7 per group) were fabricated from a single maxillary Kennedy Class II modification 1 cast using three workflows: analogue, hybrid (3D-printed wax patterns followed by casting), and fully digital (selective laser melting [SLM]). Fit accuracy was assessed using three methods: revised silicone replica technique (RSRT) as the control, generalized best fit (GBF), and localized best fit (LBF). To minimize methodological bias, SLM frameworks were used exclusively to compare assessment techniques, and the method demonstrating closest agreement with RSRT was selected for subsequent analysis. Fit discrepancies were measured in the anterior, posterior, and entire palatal regions using three-dimensional surface deviation analysis (Geomagic Control X; 3D Systems). Two-way ANOVA with Tukey HSD post-hoc tests were used for statistical analysis (α = 0.05). Results: Significant differences were observed among the assessment methods (p < 0.001), with LBF showing the closest agreement with RSRT. Based on LBF analysis, the hybrid workflow exhibited the largest palatal gaps (243.8 ± 18.8 μm overall), while the conventional workflow showed the most accurate fit (203.3 ± 18.8 μm overall). Larger gaps were observed in the anterior palate compared to the posterior palate across analogue and digital workflows. This contrasted with the hybrid group which showed larger posterior gaps compared to anterior palatal regions. Conclusions: Fit accuracy of RPD frameworks was significantly influenced by fabrication workflow and palatal region, with the hybrid workflow showing the poorest fit compared to the analogue and digital workflows. LBF was validated as a reliable digital alternative to RSRT and was used to standardize fit assessment across workflows. Clinical significance: Accurate assessment methods and optimized fabrication workflows are critical for improving the clinical fit of metal RPD frameworks. Among the techniques evaluated, both conventional and digital workflows resulted in smaller palatal gaps compared to the hybrid workflow, particularly in the anterior palate.