Background: bond strength of composite restoration contributes to endurance and survival; thus, dentin surface preparation for increased bond strengths is required.
Objectives: This study is designed to assess the effect of bromelain enzyme and Sodium hypochlorite on shear bond strength of resin composite to dentin using two adhesive systems; etch and rinse and self-etch.
Subjects and methods: Sixty (caries-free) maxillary and mandibular premolar teeth from patients aged (25-45) were used in this in-vitro experimental study.The prepared premolars were allocated into two main groups of 30 specimens according to the pretreatment agent and the bonding system used. The pretreatment agent used for dentin was divided into 3 subgroups of 10 each. specimens each Bromelain (A1), sodium hypo chlorite (A2) and control group (A3). The type of bonding system used; in the first subgroup is the self-etch bonding system (B1). The second subgroup was the total-etch bonding system (B2). Both shear bond strength (SBS), micro SBS.
Results: Regarding the control group, the self-etch system had a significantly higher value than the total-etch system . Respecting NaOCl (10%), the total-etch system had a significantly higher value than the self-etch system . Concerning Bromelain, the total-etch system had a significantly higher value than the self-etch system .

Conclusion: The prior treatment of premolar dentin with NaOCl and bromelain enzyme results in composite resins with similar SBS. In other words, after acid etching, bromelain, a safe solution with no side effects, may effectively dissolve the collagen network as effectively as NaOCl.