Objective: Self-adhesive resin cements are easy to use and do not need further preparation but their bonding ability to dentin is somehow questionable.Ddentin preparation with acidic solutions and therefore removing smear layer can increase bond strength of self-adhesive resin cements to dentin. As a matter of fact it is assumed that deproteinization of dentin can increase contact between cement and dentin. In the present study the effect of deproteinization of dentin with different concentrations and times of sodium hypochlorite on the push out bond strength of resin cement to dentin is assessed. Materials and methods 60 third molar teeth were selected and divided to 4 groups consisting of 5% and 20% concentrations and 2 and 10 minutes of using. Samples were randomly divided into six groups of ten. All samples used size 2 Whitepost FGM fiber posts (FGM, Joinville, SC, Brazil), with a diameter of 1.2 mm. Samples were cemented using dual-cure self-adhesive TheraCem (Bisco , USA), cured for 40 seconds with an LED Plus device from Woodpecker made in China All the specimens were then mounted in plastic cylinders. After 24 hours they were cut with 0.2 mm thickness diamond disc to two coronal and apical parts. Push out strength test was done with Instron 1122R (Universal Testing Machine). Results Increasing the concentration and using time of sodium hypochlorite increased push out bond strength. Discussion Deproteinization not only can increase push out bond strength but also increase time and concentration can elevate bond strength measures.

The authors have declared no competing interest.

This study did not receive any funding

I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained.

Yes

The details of the IRB/oversight body that provided approval or exemption for the research described are given below:

We commenced the study following research ethics committee of Aja university of medical sciences approval (Code: IR.AJAUMS.REC.1399.94)

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All data produced in the present study are available upon reasonable request to the authors