ABSTRACT
The purpose of this study is to investigate the effect of three different curing light sources with varying intensities on microleakage associated with class V resin -based restorations
Material and Methods: Thirty freshly extracted human premolars were cleaned and stored in 2% formaldehyde at 37° C for 24 hrs before cavity preparation. Standardized class V cavity preparations were cut on the buccal surfaces with occlusal margins on enamel and gingival margins on root dentin. Cavities were then treated with adhesives and restored using two resin-based restorative materials; Point-4 microhybrid composite resin [COMP] and Definite ormocer [ORM]. Three curing light sources with different light intensities; halogen light [HLC], plasma arc light [PAC], and light-emitting [LED] were used in this study. Specimens were divided into six groups of different curing light/restorative material combinations. Specimens were subjected to thermocycling for 600 cycles and were immersed in 1% methelyne blue dye for 24 hrs. Specimens were sectioned buc-colingually and examined under stereomicroscope at x20. Degree of dye penetration was scored at occlusal and gingival margins
Results: Kruskal-wallis non-parametric test indicated significant differences between groups at occlusal enamel margin [p < 0.027] and at gingival dentin margin [p < 0.026]. At the occlusal enamel margin, PAC /COMP showed the lowest dye penetration and PAC/ORM yielded the highest dye penetration. While at the gingival dentin margin, LED/ORM presented the lowest dye penetration and LED/COMP exhibited the highest dye penetration
Conclusions: Specimens cured with the three curing light sources included in this study exhibited microleakage. Occlusal enamel margins were associated with less microleakage than gingival dentin margins. Both microhybrid composite resin and ormocer exhibited microleakage where, in general, microhybrid composite resin showed lower degree of microleakage at occlusal enamel margins and ormocer was lower degree of leakage at gingival dentin margins. Specimens cured with plasma arc light showed the highest microleakage at occlusal enamel margins, while the lowest microleakage was associated with specimens cured with light-emitting diode at gingival dentin margins. CLINICAL SIGNIFICANCE: The combination of restorative material type and curing light source/intensity affect the marginal quality of the resin-based restorations and should be taken into consideration during the restorative procedure