Hydroxy acids for adhesion to enamel and dentin: Long-term bonding performance and effect on dentin biostability

Area of Science:

• Dental Materials Science
• Biomaterials Engineering
• Adhesive Dentistry

Background:

• Traditional phosphoric acid etching of enamel and dentin can lead to demineralization and affect long-term stability of dental restorations.
• Investigating alternative etchants is crucial for improving the durability and biocompatibility of adhesive dental materials.

Purpose of the Study:

• To evaluate hydroxy acids as potential alternatives to phosphoric acid for etching dental substrates.
• To assess their demineralization potential, bonding performance, and dentin biostability.

Main Methods:

• Enamel and dentin were etched with glycolic acid (Gly), tartaric acid (Ta), gluconic acid (Glu), gluconolactone (Gln), or phosphoric acid (Pa).
• Evaluated surface microhardness, roughness, demineralization depth, microtensile bond strength (μTBS), shear bond strength (SBS), failure modes, and dentin biostability.

Main Results:

• Hydroxy acids, particularly Gly, showed comparable or better enamel microhardness and dentin roughness than phosphoric acid.
• Hydroxy acids resulted in significantly shallower demineralization and higher dentin biostability compared to phosphoric acid.
• Gly, Glu, and Ta demonstrated adequate bonding performance, with no significant difference in μTBS between 24 hours and 1 year.

Conclusions:

• Glycolic acid, gluconic acid, and tartaric acid are potential alternative etchants for dental applications.
• These hydroxy acids offer adequate bonding performance and reduced dentin degradation, enhancing the long-term stability of adhesive restorations.