In vitro microleakage of luting cements and crown foundation material

Statement of problem. Microleakage is a concern for the long-term prognosis of a cemented crown and foundation. Purpose. The aims of this investigation were, first, to evaluate microleaka ge of zinc phosphate cement and resin-reinforced glass ionomer cement under ideal (dry) versus contaminated (wet) conditions, and second, to compare 3 foundations under both ideal and contaminated conditions. Material and methods. One hundred forty extracted molar teeth were cleaned and mounted. Tooth preparations for complete veneer cast crowns were comple ted with a chamfer finish line. A mesial surface class II cavity preparatio n 4 mm wide buccolingually and 2 mm deep was made in each tooth. Seven rest orative groups were formed: amalgam/cavity varnish, amalgam/dentinal bondin g agent, and composite/dentinal bonding agent, each with dry and contaminat ed groups, and a seventh group of class II cavity preparations without foun dations. Finish lines for crown margins were refined 1.5 mm gingival to the restoration. Artificial crowns were cast in type III gold. Treatment group s were divided into 4 cement groups: dry and contaminated zinc phosphate ce ment and dry and contaminated resin-reinforced glass ionomer cement. The sp ecimens were thermocycled and immersed in erythrosine B solution for 24 hou rs. Subsequently, they were rinsed, and their coronal portions were embedde d in clear resin. Teeth were sectioned mesiodistally and standard photomicr ographs were made. The microleakage of each restoration and crown was measu red. Results. The least foundation microleakage was recorded for amalgam/dentina l bonding agents (ideal group) and composite/dentinal bonding agents (ideal group). The most microleakage was observed within the group without a foun dation. In cement groups, the control and experiment sides were evaluated s eparately but displayed the same order of finding. The least leakage H ss r ecorded with resin-reinforced glass ionomer cement (ideal group); the most microleakage was noted noted zinc phosphate cement (ideal group). hn intera ction was demonstrated on the experimental side between cements and the fou ndations (P=.0001). Conclusion. Within the experimental conditions of this study less microleak age was recorded with resin-reinforced glass ionomer cement (ideal or conta minated) than with zinc phosphate cement (ideal or contaminated). There als o was less microleakage evident with a foundation of silver amalgam or comp osite when a dentinal bonding agent was used under ideal conditions.