Microleakage of class II packable resin composite lined with flowable composite and resin modified glass ionomer cement: An in vitro study


Background: Packable composites most commonly used as posterior restorative materials, however, disadvantageslike polymerization shrinkage limited their use, so the aim of this an in vitro study was to investigate the microleakageof posterior packable composite(Filtek™ P-60) using different liner materials; flowable resin composite(Filtek™ Flow)and resin modified glass ionomer cement (Vitrebond TM 7150) using open sandwich technique at the proximal box ofclass II preparation located above the cemento-enamel junction (CEJ)in enamel.Materials and Methods: Twenty four recently extracted human upper premolars were prepared with standardizedClass- II cavities as follows; Occlusal Outline Form: 2mm in bucco-lingual width and 1.5 mm in depth measured fromocclusal fissure to pulpal floor. Proximal Boxes: The depth of the proximal box from the proximal cavo-surface marginto the axial wall was 2mm, so as the bucco-lingual width (2mm). The proximal box margin located 1 mm coronal tothe CEJ (in enamel). The teeth were assigned into 3 groups (n=8): Group-I (control): acid etching (H3PO4) + bondingagent (Adoper Single Bond 2 Adhesive) + posterior packable composite (Filtek™ P-60), Group-II (RMGIC): acidetching + resin modified glass ionomer cement (Vitrebond TM 7150) + posterior packable composite; Group-III(Flowable): acid etching + bonding agent + flowable composite (Filtek™ Flow) + posterior packable composite.The teeth were immersed in distilled water at 37ºC for 24 h., then thermocycled (1000X, 5°-55°C, 30 sec. dwell time)and immersed in 1% methylene blue solution for 24 h., after that the teeth were sectioned longitudinally in mesiodistaldirection and dye penetration in millimeters were measured in each cavity by using stereomicroscope. Dataobtained were analyzed using ANOVA and LSD tests at 0.05 significance level.Results: The microleakage of posterior packable composite (group-I) significantly (P<0.05) decreased by the twoliners used (group-II and group-III), but there is no statistically significant differences (P>0.05) in enamel microleakagein respect to dye penetration were detected between the two liners used (group-II and group-III), with theassociation flowable composite Filtek flow (group-III) showing the best results.Conclusion: The use of flowable composite (Filtek™ Flow) and resin modified glass ionomer(Vitrebond TM 7150) in theopen sandwich technique decrease the microleakage of posterior packable composite(Filtek™ P-60) with marginlocated in enamel surface and better results with flowable composite