In vitro load-induced dentin collagen-stabilization against MMPs degradation

Area of Science:

• Biomaterials Science
• Dental Materials
• Biomineralization

Background:

• Dental restorations face degradation due to masticatory stresses, reducing bonding efficacy.
• Metalloproteinases (MMPs) play a key role in the breakdown of dentin collagen within hybrid layers.

Purpose of the Study:

• To evaluate MMPs-mediated dentin collagen degradation in hybrid layers.
• To assess the impact of different demineralization methods, resin infiltration, and mechanical loading on dentin stability.

Main Methods:

• Human dentin beams were demineralized using phosphoric acid (PA) or EDTA.
• Specimens underwent resin infiltration (Adper™ Single Bond - SB) and in vitro mechanical loading.
• Collagen degradation was quantified by measuring C-terminal telopeptide (ICTP) levels over time.

Main Results:

• Load cycling reduced collagen degradation in untreated and PA-demineralized/EDTA-treated dentin.
• Mechanical loading increased collagen degradation in PA-demineralized and EDTA-treated dentin infiltrated with SB, except for EDTA-treated samples after 4 weeks.
• Load cycling preserved initial collagen degradation levels, except in PA-demineralized/SB-infiltrated dentin, which showed increased degradation over time.

Conclusions:

• Mechanical loading enhances dentin collagen resistance to enzymatic degradation.
• EDTA demineralization results in less unprotected collagen, reducing MMPs activity.
• While load cycling increased degradation in resin-infiltrated dentin, EDTA-treated dentin exhibited consistent collagenolytic degradation.