Surface microhardness of enamel after different home bleaching procedures

Area of Science:

• Dental Materials Science
• Biomaterials
• Surface Chemistry

Background:

• Home bleaching procedures are widely used for aesthetic dental improvements.
• Understanding the effects of these treatments on tooth structure is crucial for clinical practice.
• Enamel microhardness is a key indicator of surface integrity and resistance to degradation.

Purpose of the Study:

• To evaluate how various home bleaching protocols influence the surface microhardness of human enamel.
• To compare the effects of different bleaching agents, concentrations, and application times.

Main Methods:

• 192 human incisors were divided into eight groups, including a control.
• Baseline enamel microhardness (Knoop) was measured.
• Enamel surfaces were treated for 14 days with various bleaching agents (carbamide peroxide, hydrogen peroxide, sodium chlorite) at different concentrations and durations.
• Microhardness was reassessed immediately after bleaching and after 6 weeks of storage in artificial saliva.

Main Results:

• Significant reductions in enamel microhardness were observed in groups treated with Colgate Simply White (5.9% hydrogen peroxide), Blend-a-med White Strips (5.9% hydrogen peroxide), and Odol-med3 Beauty-Kur (sodium chlorite).
• The most substantial decrease in microhardness occurred with the sodium chlorite-containing agent.
• These reductions were significant immediately after treatment and, in the case of the sodium chlorite group, persisted after storage.

Conclusions:

• Both the type and concentration of bleaching agents significantly affect enamel microhardness.
• Bleaching agents containing sodium chlorite, particularly when combined with citric acid, appear to be the most detrimental to enamel surface integrity.
• Clinicians should consider the potential impact of different home bleaching products on dental hard tissues.