Mini-iFT Confirms Superior Adhesive Luting Performance using Light-curing Restorative Composites

Area of Science:

• Dental Materials Science
• Biomaterials Engineering
• Adhesive Dentistry

Background:

• Thick indirect restorations present luting challenges due to light penetration limitations.
• Conventional light-cure resin-based composites (RBCs) are often used, but their efficacy with thicker materials requires validation.
• Dual-cure luting agents are typically recommended for thicker indirect restorations.

Purpose of the Study:

• To evaluate the mini-interfacial fracture toughness (mini-iFT) of thick indirect restorations luted with conventional light-cure RBC.
• To compare the performance of pre-heated light-cure RBC versus dual-cure RBC for luting.
• To assess the influence of interface resin bonding agent (IDS) filler load on luting efficacy.

Main Methods:

• Extracted third molars were bonded with experimental IDS (50 wt% or 75 wt% filler load).
• Two- or 6-mm thick CAD/CAM composite blocks were luted using pre-heated light-cure or dual-cure RBC.
• Mini-interfacial fracture toughness (mini-iFT) was measured using a 4-point bending test on notched samples.

Main Results:

• Mini-iFT was significantly influenced by the luting RBC type (p < 0.0001) and IDS filler load (p = 0.0011).
• Higher mini-iFT was observed with 50 wt% filler-loaded IDS and when using the light-cure RBC.
• Restoration thickness (2-mm or 6-mm) did not significantly affect mini-iFT (p = 0.39).

Conclusions:

• Pre-heated conventional light-cure RBC can be safely used for luting 2- and 6-mm thick indirect restorations under controlled light conditions.
• This light-cure strategy demonstrated superior mini-iFT compared to dual-cure luting agents.
• Lower filler content in the IDS material is favorable for enhanced interfacial bonding.