CEMENT THICKNESS OF POST AND CORES FABRICATED BY MODERN DIGITAL TECHNOLOGY

Computer-assisted digital (CAD-CAM) technologies in prosthodontics can be used for the fabrication of posts and cores. Digital techniques shorten the necessary clinical and laboratory procedures and make fabrication easier, quicker and accurate. Extracted single-rooted permanent maxillary incisors were used in the study. For each tooth one metal post was fabricated with a digital technique using SLM fabrication technology (group A) or one by casting (group B) in randomized tooth order. All the posts were cemented with zinc phosphate cement. All the teeth were sliced perpendicular to the axis of the post in four planes. The thickness of the cement layer was measured on four slices with an optical microscope with 60x and 100x magnification lens and was compared between both groups. The average cement thickness for group A was 36.76 +/- 17.29 mu m in cross-section 1, 62.38 +/- 15.24 mu m in cross-section 2, 129.42 +/- 38.37 mu m in cross-section 3, and 142.76 +/- 36.35 mu m in cross-section 4. For group B the average cement thickness was 18.18 +/- 4.6 mu m in cross-section 1, 15.36 +/- 5.41 mu m in cross-section 2, 25.41 +/- 13.42 mu m in cross-section 3, and 23.69 +/- 13.44 mu m in cross-section 4. The CAD-CAM post and core fabrication technique had a significantly larger cement thickness in all cross-sections compared to casting; however, the post accuracy was still within a clinically acceptable range.