Air Entrapment in Demineralized Dentin Adversely Affects Bonding

Area of Science:

• Dental Materials Science
• Biomaterials Engineering
• Adhesive Dentistry

Background:

• Air entrapment at the demineralized dentin-adhesive interface is a known factor compromising bond integrity.
• Understanding and mitigating air entrapment is crucial for enhancing the longevity of dental restorations.

Purpose of the Study:

• To investigate the impact of reduced air pressure during adhesive application on bond strength, nanoleakage, and degree of conversion in demineralized dentin.
• To evaluate the effectiveness of vacuum-assisted adhesive application in improving composite-dentin bond durability.

Main Methods:

• Utilized a vacuum pump to apply reduced pressures (0.08, 0.06, 0.04 MPa) during the application of a two-step etch-and-rinse adhesive to demineralized dentin, with atmospheric pressure serving as the control.
• Assessed microtensile bond strength, nanoleakage, interfacial morphology, and degree of conversion under simulated pulpal pressure and after artificial aging.
• Analyzed failure modes using the chi-squared test and other data using ANOVA.

Main Results:

• Reduced pressure application led to more thorough adhesive infiltration, decreased nanoleakage, and increased microtensile bond strength compared to control groups, irrespective of aging.
• A higher incidence of mixed failure was observed in reduced pressure groups.
• Adhesive application under reduced pressure significantly improved the degree of conversion.

Conclusions:

• Air entrapment within demineralized dentin negatively impacts the strength and durability of composite-dentin bonds.
• Applying dental adhesives under reduced pressure effectively minimizes entrapped air, thereby enhancing the long-term stability of the bond and restoration.