PubMed İndeksli Açık & Kapalı Erişimli Yayınlar
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Item Marginal fit of 3-unit CAD-CAM zirconia frameworks fabricated using cone beam computed tomography scans: an experimental study(2021) Belgin, Huseyin Berkay; Kale, Ediz; Ozcelik, Tuncer Burak; Yilmaz, Burak; 34665345Whether cone beam computed tomography (CBCT) scans can be used for the fabrication of computer-aided design and computer-aided manufacturing (CAD-CAM) fixed dental prostheses (FDPs) is not known. The purpose of the present study was to compare the marginal fit of 3-unit zirconia FDPs fabricated by using CBCT or 3-dimensional (3D) laboratory scanning. Extracted second premolar and molar teeth in a maxillary typodont model were prepared. The first molar was removed and the typodont model was scanned with a laboratory or a CBCT scanner to generate two virtual 3D cast groups (3DL and CBCT). Forty four 3-unit zirconia FDPs were designed on virtual casts and milled. The vertical marginal discrepancy (VMD) was measured by x100-magnification microscopy at seven locations on each abutment. A total of 616 measurements were made at 14 fixed locations in two groups of 22 specimens. The VMD data for 3DL and CBCT groups were statistically analyzed using the Mann-Whitney U test (alpha = 0.05). The mean VMDs on premolar ranged between 44 and 55 mu m (median: 43-55 mu m) in 3DL, and 74 and 100 mu m (median: 72-93 mu m) in CBCT; and on the molar, between 47 and 114 mu m (median: 46-114 mu m) in 3DL, and 91 and 162 mu m (median: 93-156 mu m) in CBCT. There was a significant difference between the gaps in 3DL and CBCT groups (p < 0.001). FDPs fabricated using 3D laboratory scanner had significantly smaller VMDs. Nevertheless, the 3-unit zirconia FDPs fabricated using CBCT scans presented promising marginal integrity.Item Marginal Adaptation of Provisional CAD/CAM Restorations Fabricated Using Various Simulated Digital Cement Space Settings(2018) Ozcelik, Tuncer Burak; Yilmaz, Burak; Seker, Emre; Shah, Karnik; 30231093Purpose: The ideal digital cement space value for the fabrication of provisional computer-aided design/ computer-aided manufacturing (CAD/CAM) crowns with clinically acceptable marginal adaptation is not well known. The aim of this study was to evaluate the effect of different simulated cement space settings on the marginal tit of poly(methyl methacrylate) (PMMA) provisional CAD/CAM restorations. Materials and Methods: An extracted premolar tooth was prepared using ceramic crown preparation guidelines and represented both natural teeth and/or custom implant abutments. The prepared tooth abutment was scanned with a three-dimensional (3D) laboratory scanner (D900, 3Shape). CAD design software was used to subsequently design a premolar crown core with three different simulated cement space settings (20 to 40 mu m, 20 to 50 mu m, 20 to 60 mu m). PMMA blocks were used to mill the specimens (n = 9, N = 27). Using a stereo zoom microscope, a total of 36 images for each of the 3 groups (9 crowns per group, 4 sites per crown) were captured to measure the mean vertical marginal discrepancy for every group. One-way analysis of variance (ANOVA) was used to analyze the data, and the post hoc Tukey multiple comparison test was performed. Results: The marginal gap values of the PMMA cores fabricated using the three cement space settings were significantly different from each other (P < .001). The marginal gap was smaller with a 20- to 60-mu m setting compared with 20 to 50 mu m and 20 to 40 mu m, and the 20- to 50-mu m setting allowed for smaller marginal gaps compared with 20 to 40 mu m (P < .001). Conclusion: Within the limitations of this study, the marginal gaps of CAD/CAM-fabricated PMMA cores were smaller when the cement space was larger. The smallest marginal gaps were achieved when a 20- to 60-mu m cement space was used (P < .001).