Does the choice of the measuring technique affect the comparison of fit between zirconia and cobalt–chromium prostheses?

Abstract

Aims: The objectives of the study were to compare the adaptation of presintered zirconia and cobalt– chromium prostheses using microcomputed tomography (μCT), scanning electron microscopy (SEM), and stereomicroscope (SM). Materials and Methods: Twenty-four fixed dental prostheses (FDPs) were fabricated on metal abutments, duplicated from maxillary first premolar and first molar prepared on a typodont model. Teeth were reduced to obtain chamfer of 1.2 mm and reduction occlusaly of 2 mm occlusal. Scanning of the abutments was done with random assignment to two groups receiving the FDPs made from soft-milled Co-Cr (n = 12) and zirconia (n = 12). Marginal and internal gaps were assessed using three evaluation techniques (X-ray microcomputer tomography, SEM, and stereomicroscopy). Statistical Analysis Used: Comparison of the results was made using Levene and analysis of variance tests (α =0.05). Results: Irrespective of the material tested, statistical differences were found between the measuring techniques (P = 0.001 overall); the obtained mean gaps were for CT scan (92.60 ± 13.31), for SEM (101.92 ± 23.03), and for SM (113.44 ± 14.68): the multiple comparisons between techniques found a significant difference between CT and SM (P < 0.001), and SEM and SM (P = 0.025). When materials were compared within each measuring technique, Co-Cr showed lower values compared to zirconia in SEM (P < 0.001) and Stereo (P = 0.049); similar results were found in CT. Conclusions: Results values differed with the chosen measuring technique. Co-Cr prostheses had a better fit than zirconia prostheses in SEM and Stereo. μCT showed comparable results to SEM, smaller than SM results.

Keywords

• co-cr
• fit
• microcomputed tomography
• scanning electron microscopy
• stereomicroscopy
• zirconia