Fatigue behaviour of different dentin adhesives

Area of Science:

• Dental Materials Science
• Adhesive Dentistry
• Biomaterials Engineering

Background:

• Dental adhesive systems are crucial for the longevity of resin composite restorations.
• Understanding the fatigue resistance of dentin bonds is essential for clinical success.
• Comparing different generations of adhesive systems provides insights into material evolution.

Purpose of the Study:

• To compare the quasistatic and cyclic fatigue dentin bond strength of various modern dental adhesive systems.
• To evaluate the influence of different adhesive generations on bond durability under mechanical stress.
• To assess the fatigue behavior of multi-step versus single-step adhesive systems.

Main Methods:

• In vitro study utilizing 150 human third molar discs with direct resin composite restorations.
• Application of four different generations of dentin adhesives: Syntac Classic (SY, SE), Scotchbond Multi-Purpose Plus (SB), and Prime & Bond 2.1 (PB, PE).
• Specimens underwent thermocycling followed by push-out testing for static bond strength and cyclic fatigue testing using the staircase method.

Main Results:

• Multi-step adhesive systems (SY, SE, SB) exhibited significantly higher quasistatic and cyclic bond strengths compared to single-step systems (PB, PE) (P < 0.05).
• Static bond strengths ranged from 13.4 ± 2.2 MPa (PE) to 18.5 ± 1.7 MPa (SB).
• Cyclic bond strengths showed a pronounced decrease of approximately 50% for the one-bottle system, indicating significant fatigue susceptibility.

Conclusions:

• Multi-step dental adhesive systems offer superior dentin bond strength and fatigue resistance over single-step systems.
• The fatigue behavior of adhesive systems is critical, with one-bottle systems showing a substantial reduction in bond strength under cyclic loading.
• Findings suggest that multi-step adhesive strategies contribute to more durable direct resin composite restorations.