Proteoglycans affect monomer infiltration in the etch-and-rinse bonding technique

Area of Science:

• Dental Biomaterials
• Biomineralization
• Adhesive Dentistry

Background:

• Proteoglycans (PGs) and collagen fibrils (CF) are key components of the human dentin matrix.
• Understanding their distribution is crucial for optimizing dental adhesive performance.
• Etch-and-rinse adhesives are widely used but their infiltration can be affected by dentin composition.

Purpose of the Study:

• To identify the localization of PGs and CF in human dentin using dual immunofluorescence.
• To investigate the effect of trypsin (TRY) digestion on monomer infiltration of two etch-and-rinse adhesives.
• To evaluate the impact of TRY pretreatment on hybrid layer formation.

Main Methods:

• Dual immunofluorescence labeling and confocal laser scanning microscopy (CLSM) were used to visualize PGs and CF.
• Field emission scanning electron microscopy (FE-SEM) examined dentin matrix after TRY digestion.
• Two etch-and-rinse adhesives (Adper Single Bond 2 and Prime & Bond NT) were applied to TRY-pretreated dentin.
• Hybrid layer thickness was measured using confocal micro-Raman spectroscopy.

Main Results:

• PGs were localized in dentin tubule lumens and peritubular dentin; CF were in intertubular and peritubular dentin.
• TRY digestion reduced PG fluorescence, removed organic filaments, and enlarged tubules.
• Hybrid layer thickness significantly increased (p<0.001) for both adhesives on TRY-pretreated dentin.

Conclusions:

• Dual immunofluorescence is effective for studying intact human dentin matrix.
• PGs in dentin tubules may impede adhesive monomer infiltration.
• TRY digestion enhances hybrid layer thickness, suggesting improved adhesive bonding.