Quantitative microleakage evaluation of repaired resin-based restorations with different treatments

Objectives: The successful addition of new restorative materials to an existing restoration may be the most conservative course of treatment. Repairing resin based restorations with resin materials remains a viable clinical alternative to replacement. The aim of the study was to evaluate the effect of different adhesive systems and surface treatments on the integrity of resin-resin and resin-tooth interface after partial removal of preexisting resin composites using quantitative image analysis for microleakage testing protocol. Methods: 80 defect-free human molar teeth were restored with two different types of resin composites (Filtek Z250 and GrandioSo) occlusally. The teeth were thermocycled (1000X) between 5oC and 55oC with a dwell time of 30 seconds. Mesial and distal 1/3 parts of the restorations were removed out leaving only middle part. One side of the cavity was finished with course diamond bur and the other part is sandblasted (50 µm AlO3). The samples of each composite group were randomly divided into 4 groups (n=10/group) to receive the following adhesive systems: Group1: Single Bond2 (3M); Group2: AllBond3 (Bisco); Group3: Clearfil SE (Kuraray); Group4: Beauty Bond (Shofu). All the cavities were restored with resin composite (Filtek Z250). The specimens were re-thermocycled (1000X), sealed with nail varnish, stained with 0,5% basic fuchsin for 24h, sectioned mesiodistally and photographed digitally. The extent of dye penetration was measured by image analysis software (ImageJ) for both course-finished and sandblasted surfaces at resin-tooth and resin-resin interface. The data were analyzed statistically. Results: Beauty Bond exhibited the most microleakage at every site. Surface finishing with sandblasting showed less microleakage when compared to bur finishing at every site for all the adhesive types except Beauty Bond. The type of initial repaired restorative material did not affect the microleakage. Conclusion: All-in-one adhesives may not be the choice for composite resin repair in terms of microleakage prevention.