HEMA-free versus HEMA-containing adhesive systems: a systematic review

Area of Science:

• Dental Materials Science
• Biomaterials Engineering
• Clinical Dentistry

Background:

• Hydrophilic 2-hydroxyethyl methacrylate (HEMA) in dental adhesives enhances wettability but risks hydrolytic degradation.
• HEMA-free adhesive systems are emerging to mitigate degradation issues.
• Potential phase separation between hydrophobic and hydrophilic components is a concern in HEMA-free systems.

Purpose of the Study:

• To systematically review and compare the clinical performance of HEMA-free dental adhesive systems against HEMA-containing systems.
• To evaluate retention, marginal adaptation, and discoloration of HEMA-free adhesives in direct resin composite restorations.

Main Methods:

• Systematic literature search of MEDLINE/PubMed for clinical studies (2013-2023).
• Inclusion criteria: empirical data, HEMA-free adhesives, direct resin composite restorations, minimum 2-year follow-up in permanent dentition.
• Risk of bias assessment using modified Cochrane Collaboration tool.

Main Results:

• Seven studies met the inclusion criteria from 147 initially identified.
• Most studies reported no significant difference in retention between HEMA-free and HEMA-containing adhesives.
• Conflicting results were noted for marginal adaptation and discoloration.

Conclusions:

• HEMA-free adhesive systems demonstrate satisfactory clinical retention.
• Further long-term studies are necessary to confirm clinical performance regarding marginal adaptation and discoloration.
• The clinical efficacy of HEMA-free adhesives warrants continued investigation.