Trueness of Customized Abutment Data Superimposition on Incompletely Scanned Impression: An In Vitro Study

Objectives: This study evaluated the feasibility and trueness of superimposing titanium customized abutment library data onto scans of abutments with incomplete areas along margins or proximal surfaces, comparing this approach to the CAD program's hole-filling function. Material and Methods: A dental model with one implant was used. A titanium customized abutment was scanned to create abutment library data. Reference data were generated using a laboratory scanner (Medit T500) and the abutment and neighboring teeth were scanned 10 times with Medit I500, an intraoral scanner (IOS group). Superimposition with abutment library data was performed for fully scanned (F), margin-deleted (M1 and M2), and proximal-deleted scans (P). The "Close holes" function of exocad DentalCAD was applied to create the PF group. Trueness was assessed by comparing root mean square (RMS) and point-based deviations against reference data using Geomagic control X. Statistical analysis was conducted using one-way ANOVA and Tukey HSD tests. Results: Superimposition improved trueness compared to the IOS group, reducing RMS from 42.11 +/- 1.11 to 36.37-36.61 mu m in the F, M1, M2, and P groups (p < 0.001). No significant differences were observed among superimposition groups. The PF group exhibited greater deviations than all superimposition groups (p < 0.001). Point-based analysis showed significant improvement in superimposed groups (p < 0.05), except at marginal ridges (p > 0.05). The hole-filling function did not enhance trueness (p > 0.05). Conclusions: Superimposing abutment library data improve the trueness of intraoral scans, even when areas along margins and proximal surfaces are incomplete.