Laser irradiation with Er,Cr:YSGG energy at 1 W for conditioning does not improve bond strength of Fuji II LC and Vitremer to dentin, and even reduced bond strength of Fuji II and Fuji II LC after PAA conditioning.

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Introduction: Adaptation of posterior composites to dental walls has been questioned for various reasons and polymerization shrinkage is one example. Thus, the present study investigated microleakage ocurring from different class II composite restorations techniques. Materials and Methods: In this in-vitro study class II cavities with cervical margins 1 mm below the CEJ (Cementoenamel junction) were prepared in 64 extracted human premolars. The teeth were randomly divided into two groups. Group 1 (open sandwich): Glass ionomer was injected on the floor of the cavity and the rest of the cavity was restored using composite resin using incremental technique. Group 2 (Snowplow) one layer of flowable composite was placed in the bottom of the cavity and was co-cured with the first layer of composite resin. The rest of the cavity was restored the same as group 1. To evaluate the microleakage, the specimens were thermocycled for up to 3000 cycles and immersed in 1% methylene blue solution for 72 hours. Then they were sectioned mesiodistally and evaluated under a stereomicroscope. Data were analyzed via Mann-Whitney and Fishers exact test and p value < 0.05 was considered significant. Results: The mean value for microleakage in group 1 (795.74 ± 494.04 mμ) was lower than group 2 (972.99 ± 457.8 mμ), but the results were not statistically significant (p value = 0.117). Conclusion: It appears that microleakage in both open sandwich technique and Snowplow technique did not portray statistical significance, so both of them can be used.