Micro-Computed Tomography Evaluation of the Marginal and Internal Fit of Ceramic-Filled Resin Crowns Fabricated by Subtractive and Additive Manufacturing.

Abstract

Purpose: The purpose of this in vitro study was to compare the marginal and internal fit of ceramic-filled resin crowns fabricated using subtractive manufacturing (SM) and additive manufacturing (AM) techniques and to evaluate the effect of stereolithography (SLA) and digital light processing (DLP) technologies on restoration adaptation.

Materials and methods: Thirty-three ceramic-filled resin crowns were fabricated for a standardized mandibular first molar preparation and assigned to 3 groups (n = 11): SM, SLA-based AM, and DLP-based AM. Crowns were designed using a standardized digital workflow with a 50-μm cement space and cemented with a radiopaque dual-cure resin cement. Marginal and internal gaps were assessed by micro-computed tomography using linear measurements from coronal and sagittal sections at 18 predefined locations. Non-parametric statistical analyses were performed (α = 0.05), and correlations between marginal and internal gap values were evaluated.

Results: Significant differences were identified among manufacturing techniques at selected marginal and internal locations (p = 0.005 to p = 0.047). DLP-fabricated crowns exhibited lower gap values, particularly in the marginal and axial regions. Region-based analysis revealed significant differences between SLA and DLP in the marginal region (p = 0.048) and between DLP and SM in the internal region (p = 0.031). All techniques produced gap values within clinically acceptable limits, and a positive correlation was observed between marginal and internal gaps.

Conclusions: The manufacturing technique significantly affected the marginal and internal fit of ceramic-filled resin crowns. Although all techniques produced clinically acceptable results, DLP-based additive manufacturing demonstrated superior overall adaptation. DLP-based additive manufacturing may be considered a predictable alternative to subtractive manufacturing for definitive crown fabrication.