Interfacial gap formation of class II composite restorations with proximal box elevation using bulk-fill materials: a...

Area of Science:

• Restorative Dentistry
• Dental Materials Science

Background:

• Class II direct restorations are prone to marginal discrepancies.
• Proximal box elevation (PBE) is a technique to improve adaptation in deep cervical preparations.
• Bulk-fill resin composites offer potential advantages in handling and placement efficiency.

Purpose of the Study:

• To evaluate interfacial gap formation in Class II direct restorations using different bulk-fill resin composites for PBE.
• To compare the efficacy of various bulk-fill materials in reducing cervical gap formation.

Main Methods:

• Standardized Class II cavities were prepared in human molars.
• Five groups were tested: sonic-activated, low-viscosity, thermo-viscous, bioactive dual-cure bulk-fill composites for PBE, and a control group with no PBE.
• Specimens underwent thermocycling, and interfacial gaps were analyzed using micro-computed tomography (micro-CT).

Main Results:

• Sonic-activated and thermo-viscous bulk-fill composites showed significantly higher gap formation compared to low-viscosity, bioactive dual-cure bulk-fill, and the control group.
• No significant differences in gap formation were observed between low-viscosity, bioactive dual-cure bulk-fill, and the control group.
• Low-viscosity and bioactive dual-cure bulk-fill composites demonstrated reduced interfacial gaps at the cervical region.

Conclusions:

• Proximal box elevation using low-viscosity and bioactive dual-cure bulk-fill composites effectively minimizes interfacial gaps in Class II restorations.
• These materials are suitable for deep Class II restorations due to superior cavity adaptation.
• Low-viscosity and bioactive dual-cure bulk-fill composites are recommended for improved cervical adaptation.