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Abstract
This study was conducted to evaluate microshear bond strength of self adhering flowable composite to enamel and dentin, without surface treatment and after different surface treatment protocols compared to flowable composite. Thirty two carious free extracted molars were selected in the current study. The teeth were wet ground to expose fresh flat enamel or dentin surfaces where each surface will carry five specimens. Teeth were randomly divided into two main groups according to restorative tested material; either flowable composite (Filtek{u2122} Z350 XT Flowable) or self-adhering composite (Fusio{u2122}Liquid Dentin). Each group was divided into four subgroups according to surface pretreatment; either without any surface treatment, with acid etching only, with self etching adhesive system and with etch and rinse bonding system. Each subgroup was divided into two classes according to type of substrate; either enamel or dentin. Sixteen subgroups were created (n=10) with a total number of 160 specimens. A plastic tube (tygon tube), 0.7 mm in diameter and 1mm in length was held securely and immobilized using cotton pliers on the indicated substrate with or without surface treatment, then was restored for microshear bond strength testing according to manufacturer instructions. Microshear bond strength test was conducted immediately after 24 hours using universal testing machine at crosshead speed of 0.5 mm/min till specimens fail, bond strength was calculated and failure modes were analyzed. The results showed that Filtek{u2122} Z350 XT Flowable with surface treatment using etch and rinse bonding system has the highest statistically significant bond strength to enamel, while least statistically significant bond strength was for Fusio{u2122}Liquid Dentin with surface treatment using self etch system and without any surface pretreatment. In dentin, the highest statistically significant bond strength was for Fusio{u2122}Liquid Dentin with surface treatment using self etch system, while the least bond strength was for Fusio{u2122}Liquid Dentin with etching only and Fusio{u2122}Liquid Dentin without surface treatment, in addition applying Filtek{u2122} Z350 XT Flowable without surface treatment following manufacturer instructions showed premature failure for both enamel and dentin