Effect of two bleaching regimens on enamel bonding performance

Area of Science:

• Dental Materials Science
• Biomaterials Engineering
• Adhesive Dentistry

Background:

• Dental bleaching is a common aesthetic procedure.
• Bleaching agents can potentially affect the bonding of dental materials to tooth structure.
• Understanding the impact of bleaching on adhesive performance is crucial for clinical success.

Purpose of the Study:

• To evaluate the post-bleaching bonding performance of one-step and two-step self-etch adhesives (SEA) to bleached bovine enamel.
• To investigate the effect of different post-bleaching time intervals on bond strength.
• To analyze the formation of acid-base resistant zones (ABRZs) after bleaching and adhesive application.

Main Methods:

• Bovine enamel surfaces were subjected to in-office or at-home bleaching.
• Adhesive application (one-step and two-step SEA) was performed at immediate, 1-day, 1-week, and 1-month post-bleaching intervals.
• Microshear bond strengths (µSBS) were measured 24 hours after bonding.
• Acid-base resistant zones (ABRZs) were examined using Scanning Electron Microscopy (SEM).

Main Results:

• Bleaching significantly decreased the immediate µSBS for both one-step and two-step SEA.
• Bond strength gradually increased over the observed post-bleaching time periods.
• Thick ABRZs were observed in both adhesive groups after bleaching, indicating enamel surface changes.

Conclusions:

• Dental bleaching adversely affects the immediate bond strength of self-etch adhesives to enamel.
• The bonding performance of SEA to bleached enamel improves with time post-bleaching.
• The formation of ABRZs suggests a potential interaction between bleaching agents and enamel surface properties.