Effect of Two Different Deproteinizing Agents on Microtensile Bond Strength between Resin Composite and Deep Dentin using Two Restorative Protocols. An In-Vitro Study

Document Type : Original Article


1 B.D.S Faculty of Oral and Dental Medicine, Misr International University

2 Professor of Operative Dentistry, Misr International University.

3 Professor of Operative Dentistry, Cairo University.

4 Lecturer of Operative Dentistry, Misr International University.


The purpose of this study was to evaluate the microtensile bond strength of resin composite to deep dentin using two different restorative protocols. Materials and Methods: Forty-five sound permanent molars were selected to expose deep dentin. Teeth were etched with 37% phosphoric acid then rinsed. Teeth were divided into five equal groups (n=9) according to deproteinizing method. Group 1: only etching (control), Group 2 and 3: deproteinized with 10% sodium hypochlorite Group 4 and 5: deproteinized with 10% bromelain enzyme. Teeth were restored with two restorative protocols either: packable nanohybrid bulk-fill resin composite or bulk-fill flowable and packable bulk-fil nanohybrid resin composite. Teeth were stored in distilled water (37°C/24 hours) then sectioned into beams. The beams were subjected to microtensile bond strength testing using a universal testing machine at a crosshead speed of 0.5 mm/min until failure occurred. Results: There was a statistically significant difference (p<0.05) between microtensile bond strength values of different groups. Group 1 recorded the highest microtensile bond strength with non-statistically significant difference from Group 4 but a statistically significantly higher microtensile bond strength than other groups. Group 5 recorded the lowest mean microtensile bond strength. Conclusion: Deproteinization of deep dentin, either with 10% sodium hypochlorite solution or 10% bromelain enzyme solution, has no improvement effect on microtensile bond strength with the packable bulk-fill resin composite used in this study. Application of flowable bulk-fill resin composite, as a liner, has a deterioration effect on the microtensile bond strength of deproteinized deep dentin to packable bulk-fill resin composite.


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