Effect of Prolonged Thermal Cycling on Microleakage Around Class V Cavities Restored With Glass-Ceramic Inserts With Different Coefficients of Thermal Expansion. An In Vitro Study

Author： Santini Ario Ivanovic Vladimir Tan Chuei Luan Ibbetson Richard

Publisher： Faculty of General Dental Practice (UK)

ISSN： 1741-9344

Source： Primary Dental Care, Vol.13, Iss.4, 2006-10, pp. : 147-153

Disclaimer: Any content in publications that violate the sovereignty, the constitution or regulations of the PRC is not accepted or approved by CNPIEC.

Previous Menu Next

Abstract

Purpose: The purpose of this in vitro study was to evaluate microleakage around Class V glass-ceramic restorations of different coefficients of thermal expansion after prolonged thermal cycling.Materials and Methods: One hundred and twenty non-carious extracted human premolars (patient age range 12-20 years) were randomly assigned to three groups. Standard Class V preparations were cut in the buccal surface using customised Cerana burs, size no. 3. Glass-ceramic inserts from two manufacturers (Cerana, Nordiska Dental AB, Helsingborg, Sweden; BetaQuartz, Hager & Werken GmbH, Duisburg, Germany) were used to restore the cavities and were luted with a hybrid, high-viscous composite (Tetric Ceram, Ivoclar Vivadent, Schaan, Liechtenstein) and a bonding agent (Excite, Ivoclar Vivadent, Schaan, Liechtenstein). A control group, without inserts, was bulk-filled with the same composite used as the luting agent. In accordance with American Dental Association guidelines, half of the preparation was in enamel, half in dentine/cementum and had a mesio-distal width of 3 mm, an occluso-gingival height of 3 mm, and a depth of 2 mm. All margins had butt joints. Sixty teeth, selected at random, were not thermal cycled; the remaining 60 teeth were thermal cycled 4000 times between water baths held at 5°C and 55°C and the specimens prepared and examined for microleakage using 2.0% Procion Red^® (ICI, Slough, UK) dye, buffered at pH7, as a marker. The results were analysed using the Kruskal-Wallis test (ANOVA) at a 95% significance level.Results: At the occlusal margins there was no significant difference in microleakage between the three groups (P>0.5) without thermal cycling. After thermal cycling, microleakage at the occlusal margins was significantly less around cavities restored with Cerana glass-ceramic inserts versus Beta-Quartz and Tetric Ceram (P<0.05 in both cases). At the gingival margins, there was no significant difference in microleakge between the groups before thermal cycling (P>0.5). After thermal cycling, there was significantly less microleakage between Cerana inserts and Tetric Ceram (P<0.05). Comparisons between non-thermal cycled and thermal cycled groups showed there was no significant difference with the Cerana inserts (P=0.5590).Clinical Implications: The results indicate that, after thermal cycling, restorations restored with Cerana glass-ceramic inserts, which have a coefficient of thermal expansion approximating to that of enamel, show a decrease in marginal microleakage, compared with Beta-Quartz glass-ceramic inserts and Tetric Ceram resin-based composite material. Restorative materials, which have a coefficient of thermal expansion approximating to that of enamel, would seem to be the materials of choice in reducing the problem of marginal microleakege.