An Investigation Into Factors Affecting Microleakage Determination of Dental Restorations

Objective: To evaluate the effect of variation in dwell time, temperature and number of thermocycles on microleakage of dental restorations. Methods: A total of 135 extracted human premolars were used. Apices were cut off and circular cavities prepared. Restorations were completed using Prime&Bond and Dyract AP (Dentsply) to eliminate the risk of microleakage at an apical level. Class V cavities were prepared on the buccal surfaces at the cemento-enamel junction. Xeno III/ EsthetX was used to restore these cavities. After storing teeth in saline for 24 hours, all restorations were polished using Soflex discs. Teeth were coated with 2 layers of varnish except for 1mm around the restoration. Teeth were randomly divided into 9 groups: Three Groups subjected to 200 cycles, dwell time 60 seconds, and temperatures of 5°C- 55°C(Group A), 15°C- 45°C (Group B), 25°C- 35°C (Group C). 3 Groups subjected to dwell time 30 seconds, temperature 5°C-55°C and 400 cycles (Group D), 200 cycles (Group E), and 100 cycles (Group F). 3 Groups subjected to 200 cycles, temperature 5°C- 55°C and dwell time 120 seconds (Group G), dwell time 60 seconds (Group H) and dwell time 30 seconds (Group I). After cycling, varnish was removed. Teeth were sectioned and examined under light microscope for dye penetration. Results: Dentinal microleakage was lowest but highest into enamel for Group A. Dentinal microleakage was higher in Group D (400 cycles) as compared to Groups E & F. Dentinal microleakage was highest with dwell time of 120 seconds. Conclusions: Increase in dwell time increased microleakage into dentine and enamel. Increase in cycles increased microleakage into dentine. Temperature range of 5°C-55°C showed the highest dye penetration into enamel.