Comparison of internal compatibility of endocrown restorations madewith different materials and technics

The aim of this study is to compare the internal and marginal adaptation of endocrown restorations fabricated using different materials and techniques. In this in vitro study, a total of 28 extracted human molar teeth, free of caries and with similar morphological characteristics, were used. After extraction, the teeth were stored in water. Throughout the research process, all teeth were processed under similar conditions during both measurement and application phases, to ensure the comparability of the materials.Group 1: Conventional impressions were taken using silicone impression material (Durosil C Silicone), and a stone model was obtained. Endocrowns were fabricated on this model using a nanohybrid composite material (Universal Nano Hybrid Composite).Group 2: Digital impressions were taken directly from the prepared teeth using an intraoral scanner (Trios 5, 3Shape A/S). The restorations were designed using CAD software (3Shape Dental Manager 2021) and produced using a 3D printer (NextDent 5100 3D Printer) with a 3D resin material (C&B MFH - Micro Filled Hybrid).Group 3: Digital impressions were taken directly from the prepared teeth using an intraoral scanner (Trios 5, 3Shape A/S). The restorations were designed with CAD/CAM software (ExoCad; Onex Dental) and fabricated using feldspathic glass ceramic blocks (G-Cream Blocks).Group 4: Conventional impressions were taken and a stone model was obtained. The model was scanned using a laboratory scanner, and the restorations were designed using CAD/CAM software (ExoCad; Onex Dental) and fabricated from feldspathic glass ceramic blocks (G-Cream Blocks).All endocrowns were cemented using a resin cement (Panavia F 2.0 - Universal Resin Cement Set). Each sample was sectioned into four parts using a separating saw, and the internal and marginal cement gaps were measured under a stereomicroscope (Olympus SZ40 Stereo Microscope). Cement thicknesses were measured in micrometers (µm) and recorded. The results were statistically analyzed using the One-Way ANOVA test in the SPSS program.The mean internal gap values were found to be: Group 1: 259.53 µm ,Group 2: 278.78 µm ,Group 3: 234.32 µm ,Group 4: 260.75 µm ,Group 3 showed the lowest internal gap value, while Group 2 showed the highest.The mean marginal gap values were: Group 1: 150.00 µm,Group 2: 179.57 µm,Group 3: 185.28 µm,Group 4: 236.57 µm Group 1 had the lowest marginal gap, while Group 4 had the highest.In this study, Group 1 showed the best numerical marginal adaptation, while Group 3 demonstrated the best numerical internal adaptation. However, no statistically significant differences were found between the groups in terms of either measurement.