Dentin adhesives application deviations: Effects on permeability and nanoleakage.

Area of Science:

• Dental Materials Science
• Adhesive Dentistry

Background:

• Proper application of etch-and-rinse adhesive systems is crucial for effective dentin sealing.
• Deviations from recommended protocols can compromise the integrity of the hybrid layer and lead to nanoleakage.

Purpose of the Study:

• To investigate how specific deviations from a two-step etch-and-rinse adhesive system protocol affect dentin permeability and nanoleakage.
• To determine which protocol modifications enhance or compromise the sealing ability of the adhesive system.

Main Methods:

• One hundred and twenty dentin disks were subjected to a two-step etch-and-rinse adhesive system.
• Five deviations were tested: potassium oxalate application, reduced adhesive application time, avoided adhesive drying, aggressive adhesive drying, and double adhesive application.
• Permeability was assessed using Kruskal-Wallis and Tukey's tests.
• Nanoleakage was analyzed via transmission electron microscopy (TEM) on twelve additional samples.

Main Results:

• Aggressive drying, oxalate application, and double adhesive layers significantly reduced dentin permeability and improved hybrid layer infiltration.
• Reduced adhesive application time or insufficient drying resulted in increased dentin permeability and extensive nanoleakage.
• Compromised dentin sealing was observed with protocols involving reduced application time or inadequate drying.

Conclusions:

• Certain deviations, such as aggressive drying or oxalate use, can enhance the performance of two-step etch-and-rinse adhesives by improving hybrid layer infiltration.
• Conversely, reducing application time or insufficient drying compromises dentin sealing, leading to immediate nanoleakage and potential clinical issues.
• Optimizing adhesive application technique is critical for achieving durable and effective dentin bonding.