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Selective enamel etching reconsidered: better than etch-and-rinse and self-etch?
Roland Frankenberger1, Ulrich Lohbauer, Matthias J Roggendorf
1Dental Clinic 1, Operative Dentistry and Periodontology, University Medical Center, University of Erlangen-Nuremberg, Germany. frankbg@dent.uni-erlangen.de
The Journal of Adhesive Dentistry
|December 9, 2008
Summary
Phosphoric acid etching improved enamel bonding in direct resin composite restorations. Self-etching adhesives performed best on dentin when used as directed, but their performance decreased under etch-and-rinse conditions.
Area of Science:
- Dental Materials Science
- Adhesive Dentistry
- Restorative Dentistry
Background:
- Direct resin composite restorations are widely used for dental caries treatment.
- Achieving durable marginal integrity in both enamel and dentin is crucial for restoration longevity.
- Various bonding strategies, including selective enamel etching, etch-and-rinse, and self-etching adhesives, are employed to enhance restoration quality.
Purpose of the Study:
- To evaluate and compare the marginal quality of direct resin composite restorations bonded with different adhesive systems.
- To assess the performance of selective enamel etching, etch-and-rinse, and self-etching adhesives before and after thermomechanical loading (TML).
- To investigate the influence of bonding protocols on enamel and dentin margin integrity.
Main Methods:
- Eighty human third molars with MO cavities were restored using various direct resin composite systems and bonding agents.
- Adhesive systems tested included 4-step selective enamel etching, 4-step etch-and-rinse, 2-step etch-and-rinse, and 2-step self-etching adhesives.
- Marginal gap analysis was performed using epoxy resin replicas examined under scanning electron microscopy before and after TML.
Main Results:
- Initially, all adhesives showed high percentages of gap-free margins.
- After TML, phosphoric acid etching on enamel yielded superior results (~90%) compared to two-step self-etching adhesives (~70%).
- For dentin margins, self-etching adhesives used as directed provided the best quality (74-82%), while their use under etch-and-rinse conditions significantly reduced quality (35-42%).
Conclusions:
- Phosphoric acid etching generally enhances enamel bonding effectiveness for direct resin composite restorations.
- The marginal quality of two-step self-etching adhesives in enamel can be improved by selective phosphoric acid etching.
- Adhesive system choice and application protocol significantly impact marginal integrity in both enamel and dentin, especially after functional loading.
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