Quantitative assessment of surface microhardness of esthetic restorative materials after exposure to different immersion regimes in a cola drink: An in vitro study

Abstract

Objective: To compare the effect of different immersion regimes in a cola drink on surface microhardness of esthetic restorative materials. Subjects and Methods: Two hundred samples were grouped into four equal groups of fifty samples each: Group I - conventional glass ionomer, Group II – resin-modified glass ionomer, Group III - polyacid-modified resin composite, and Group IV - composite resin. Each group was further subdivided into five subgroups of ten samples each: Subgroup A - samples were kept immersed in artificial saliva. Subgroup B - samples were immersed in cola drink once a day. Subgroup C - samples were immersed in cola drink, three times a day. Subgroup D - Samples were immersed in cola drink five times a day. Subgroup E - samples were immersed in cola drink ten times a day. Each immersion lasted 5 min. The immersion protocol was repeated for 7 days. Results: Maximum microhardness was seen in composite resin samples followed by conventional glass ionomer, polyacid-modified resin composite, and least microhardness was seen in resin-modified glass ionomer. Conclusion: Resistance to change in surface microhardness was seen in the following sequence: Composite resin > polyacid-modified resin composite > resin-modified glass ionomer > conventional glass ionomer.