Comparison of reconstruction of cement space in resin copings fabricated with the use of a 3D printer in single- and three-unit restorations

Abstract

Marginal and internal gaps are very important factors in fixed prosthetic restorations. The marginal fit is affected by the cementing process of the restoration. One of the techniques used to create the required space between the prepared tooth and the crown is to use a die spacer. The aim of the current study was to assess the accuracy of reconstruction of the cement space in the resin copings of extracoronal restorations fabricated with the use of the 3D printing technique and compare it in single- and three-unit restorations. After taking impressions from the left maxillary first premolar and first molar teeth of a jaw model, a total of 20 models were prepared with the use of a 3D printer for single-unit and three-unit groups (a total of 120 samples) and cemented on their relevant dies. The samples were sectioned buccolingually. The images of the internal gaps were prepared under a light microscope and evaluated. The values in different groups were compared in relation to marginal and internal fit and analyzed with ANOVA (mixed models). Statistical significance was set at P<0.05. Comparison of the accuracy of reconstruction of the cement space in resin copings fabricated with the use of a 3D printer showed that in the single-unit premolar tooth with a presumptive cement space of 45 µm the cement space was 30.45±20.01 µm (P>0.001) at the margin and 36.01±13.52 µm (P>0.001) in the internal area; in the reconstruction of the three-unit molar tooth with a presumptive cement space of 25 µm, the cement space at the margin was 105.97±33.7 µm (P>0.964), with 120.09±63.15 µm (P>0.005) in the internal area. It was concluded from the results of the present study that the accuracy of reconstruction of the cement space in resin copings fabricated with the use of a 3D printer in samples with a larger presumptive cement space was higher than that in samples with a smaller presumptive cement space. The accuracy of the reconstruction of the cement space in resin copings fabricated using a 3D printer in single-unit restorations was higher than that in three-unit restorations.