Marginal fit of 3-unit CAD –CAM zirconia frameworks fabricated using cone beam computed tomography scans: an experimental study

AbstractWhether 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 ×100-magnificat ion 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–WhitneyU test (α = 0.05). The mean VMDs on premolar ranged between 44 and 55 µm (median: 43–55 µm) in 3DL, and 74 and 100 µm (median: 72–93 µm) in CBCT; and on the molar, between 47 and 114 µm (median: 46–114 µm) in 3DL, and 91 and 162 µm (median: 93–156 µm) in CBCT. There was a signific ant 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 ...
Source: Odontology - Category: Dentistry Source Type: research