Twenty-month Performance of a Universal Bonding System on Simulated-challenged Dentin Substrates Pretreated with...

Area of Science:

• Dental Materials Science
• Adhesive Dentistry
• Biomaterials

Background:

• Universal adhesives (UAs) are widely used in restorative dentistry.
• Antiproteolytic agents like chlorhexidine (CHX) are sometimes used with UAs.
• Potential degradation of the bonding interface by CHX necessitates further investigation.

Purpose of the Study:

• To evaluate the long-term bond strength of a universal adhesive with and without CHX on sound, eroded, and carious dentin.
• To assess the influence of CHX pretreatment on the durability of the adhesive bond interface.
• To analyze failure modes and determine the impact of substrate alteration and CHX on bond longevity.

Main Methods:

• Human molar specimens were divided into sound, eroded, and carious groups.
• Specimens were pretreated with water or CHX before universal adhesive application.
• Micro-tensile bond strength (μTBS) was tested at 24 hours, 6 months, and 20 months; failure modes were analyzed via microscopy.

Main Results:

• Bond strength significantly decreased over 20 months, particularly on eroded and carious dentin treated with CHX.
• Sound dentin exhibited higher μTBS values compared to altered substrates.
• SEM revealed heterogeneous hybrid layer patterns in CHX-treated groups, especially on altered dentin.

Conclusions:

• Long-term use of universal adhesives with MDP in self-etch mode reduces dentin bond strength.
• Erosion and caries significantly impair dentin adhesion when using universal adhesives with CHX.
• Avoid clinical application of universal adhesives with MDP and CHX on eroded or carious dentin.