Influence of post-bleaching time intervals on dentin bond strength

Area of Science:

• Dental Materials Science
• Restorative Dentistry
• Biomaterials

Background:

• Resin-dentin bond strength can be compromised after dental bleaching.
• Internal bleaching of non-vital teeth may impact the adhesion of restorative materials.

Purpose of the Study:

• To evaluate the effect of non-vital tooth bleaching on the shear bond strength (SBS) of composite resin to bovine dentin.
• To assess the influence of delayed bonding intervals after internal bleaching on SBS.

Main Methods:

• A randomized block design was used with 256 teeth subjected to four bleaching treatments: sodium perborate/hydrogen peroxide (SPH), sodium perborate/water (SPW), carbamide peroxide (CP), and distilled water (CON).
• Composite resin cylinders were bonded to dentin and tested for SBS after storage in artificial saliva for 0, 7, 14, and 21 days.
• Bleaching agents were replaced weekly for 4 weeks, and SBS was measured using a universal testing machine.

Main Results:

• No significant interaction was found between time intervals and bleaching agents on SBS.
• The time factor was not statistically significant (p > 0.05).
• Shear bond strength was significantly reduced with SPH and SPW treatments compared to CON and CP treatments ([CON = CP] > [SPW = SPH]).

Conclusions:

• Internal bleaching of non-vital teeth using sodium perborate (with or without water) negatively affects resin-dentin shear bond strength.
• Carbamide peroxide bleaching did not significantly impact resin-dentin bond strength.
• The timing of bonding procedures after bleaching with sodium perborate did not influence the observed reduction in bond strength.