Comparison of the marginal and internal fit of PMMA interim crowns printed with different layer thicknesses in 3D-printing technique.

Abstract

The aim of this in vitro study was to compare the effect of printing layer thickness on the marginal and internal fit of interim crowns. A maxillary first molar model was prepared for ceramic restoration. Thirty-six crowns were printed with three different layer thicknesses using a digital light processing-based three-dimensional printer (25, 50, and 100 µm [LT 25, LT 50, and LT 100]). The marginal and internal gaps of the crowns were measured with replica technique. An analysis of variance was conducted to determine if there were significant differences between the groups (ɑ = .05). The marginal gap of LT 100 group was significantly higher than that LT 25 (p = .002) and LT 50 groups (p ≤ .001). The LT 25 group has significantly larger axial gaps than LT 50 group (p = .013); however, there were no statistically significant differences between other groups. The LT 50 group showed the smallest axio-occlusal gap. The mean occlusal gap differed significantly by printing layer thickness (p ≤ .001), with the largest gap occurring for LT 100. Provisional crowns printed with 50 µm layer thickness provided the best marginal and internal fit. It is recommended that provisional crowns be printed with a 50 µm layer thickness to ensure optimal marginal and internal fit.