Comparison of Preveneered Crowns Repair Methods using Microleakage and SEM

Objectives: To assess and compare two repair methods for preveneered stainless steel crowns (SSCs) using microleakage and scanning electron microscopy (SEM).
Methods: A quadrangular cavity with an internal space of 4 x 4 x 2 mm was made in the labial surface of thirty preveneered anterior SSC crowns (NuSmile). Specimens were randomly divided according to the surface treatment into three groups of ten each. Group 1 served as control with no surface treatment and repaired with Tetric EvoCeram. The exposed metal in group 2 was roughened using an inverted cone bur and group 3 was not roughened and both groups treated with Ceramic Repair Kit (Ivoclar Vivadent) and repaired with Tetric EvoCeram. The repaired specimens were stored in distilled water for 24 hours and prepared for microleakage/dye penetration and immersed for four hours in a 2% methylene blue dye solution. The specimens were transversely sectioned and evaluate/scored dye penetration. Selected sections of repaired crowns were evaluated under SEM. Data were analyzed using the Kruskal-Wallis test and Pairwise comparisons were then made using the Mann-Whitney test.
Results: Dye penetration in the control group was seen around the entire repair interface in 20% of the specimens. There was statistically significant differences between the three groups (P<.05). There was a statistically significant difference between control group and the two experimental groups. Control group with no surface treatment showed the highest mean dye penetration. There was no significant difference between group 2 (roughened) and group 3 (not roughened). SEM of the experimental groups showed intimate continuous internal adaptation with no observable gap at the repair interfaces.
Conclusions: The method of repair used in this study with and without surface roughening of the metal and use of Ceramic Repair Kit and Tetric EvoCeram prevented dye penetration at the preveneered SSCs and repair material interface.