An evaluation of microleakage of metallic copings cemented with three luting agents: A stereomicroscopic in vitro study

Abstract

Aim: The aim of the study was to assess, compare and evaluate the microleakage at the margins of cast metal copings cemented with three luting agents. Materials: (A) Intact human molars, normal saline solution, (B) Medium inlay casting wax, die spacer-Durolon® , (C) Phosphate-bonded investment material-Ceramvest® , nickel-chromium base metal alloy, (D) Glass ionomer cement-Ketac™ Cem, resin-modified glass ionomer cement-RelyX™ Luting 2, resin cement-RelyX ARC, (E) 50% silver nitrate stain, developer-D-76 Eastman Kodak, 150 watt flood lamp and (F) Epoxy resin, carborundom disc. Methods: A comparative study was done to evaluate the ability of three contemporary luting agents to resist microleakage in cemented nickel-chromium complete metal copings cast on prepared molars. The copings were placed back on the respective prepared teeth to check the fit and marginal adaptation was observed under an optical microscope. Copings with marginal discrepancies of more than 39 µm were rejected and castings were repeated for accurate marginal fit. The castings were cemented with the three luting agents under study, namely, glass ionomer cement, resin-modified glass ionomer cement and resin cement under ideal conditions. The cemented specimens were thermocycled after 24 hours between 5°C and 50°C. After thermocycling, the teeth were treated with 50% silver nitrate solution for 60 minutes, placed under a 150 watt flood lamp for five minutes to allow complete fixation of any unfixed stain, embedded in clear epoxy resin and sectioned twice longitudinally. Results: It was concluded from the study that the glass ionomer cement, Ketac Cem showed less microleakage than the resin-modified glass ionomer cement, RelyX Luting 2 and the resin cement, RelyX ARC. The resin cement was associated with a higher degree of microleakage than the glass ionomer cement and the resin-modified glass ionomer cement.