Flowable composites as intermediate agents without adhesive application in resin composite repair.

Area of Science:

• Dental Materials Science
• Restorative Dentistry
• Biomaterials Engineering

Background:

• Achieving durable composite-to-composite bonds is crucial for longevity of dental restorations.
• Intermediate resin agents are used to enhance adhesion between new and old composite materials.
• Understanding the influence of different intermediate agents on bond strength is essential for clinical success.

Purpose of the Study:

• To evaluate the impact of various intermediate resin agents on the microtensile bond strength (microTBS) between composite materials.
• To compare the effectiveness of flowable composites versus dental adhesives as intermediate agents.
• To assess the influence of different composite substrates on bond strength.

Main Methods:

• Two composite substrates (Gradia Direct Anterior, Filtek Supreme XT) were prepared and treated with five intermediate agents: two flowable composites and two adhesives, plus a control (no agent).
• Repaired specimens were tested for microtensile bond strength (microTBS) after aging.
• Failure modes and interfacial quality were analyzed using stereo- and scanning electron microscopy (SEM).

Main Results:

• Both composite substrate and intermediate agent significantly affected microTBS (P < 0.001).
• Flowable composites yielded significantly higher microTBS than adhesives and the control group (P < 0.001).
• Gradia Direct Anterior demonstrated higher bond strengths than Filtek Supreme XT, with predominantly cohesive failures observed with flowable composites.

Conclusions:

• Flowable composites are superior intermediate agents for enhancing composite-to-composite bond strength compared to conventional adhesives.
• The choice of composite substrate and intermediate agent critically influences the bond durability.
• SEM analysis confirmed good interfacial quality with flowable composites and adhesives, supporting their clinical application.