Influence of NaOCl deproteinization on shear bond strength in function of dentin depth

Purpose: To determine the influence of NaOCl application on shear bond strengths (SBS) to superficial and deep dentin, using Prime & Bond 2.1. Materials and Methods: Superficial and deep dentin was exposed in 40 extracted third molars by sectioning the occlusal surface immediately under the enamel-dentin junction or close to the pulp chamber. After polishing the dentin disks (600-grit SiC), they were assigned to two groups: (1) 36% orthophosphoric acid for 15 seconds, or (2): 36% orthophosphoric acid for 15 seconds followed by 5% sodium hypochlorite (NaOCl) for 2 minutes. The dentin adhesive was applied as per manufacturer's instructions, followed by TPH resin-based composite. The specimens were stored in water for 24 hours at 37°C and thermocycled x500 and SBS were determined. Data were statistically analyzed with ANOVA and Student's t-test. Results: For acid-etched specimens, superficial dentin resulted in statistically higher mean SBS than deep dentin. After NaOCl application, deep and superficial dentin resulted in statistically similar mean SBS. Collagen removal did not affect mean SBS on superficial dentin, while SBS values on deep dentin were increased.