Fracture Resistance of Maxillary Premolars With Class II MOD Cavities Restored With Direct and Indirect Resin Composite Restorative Systems.

OBJECTIVE

To assess the fracture resistance of maxillary premolars with mesio-occluso-distal (MOD) Class II cavities restored with lab composite and microhybrid resin composite, with or without a short fiber-reinforced composite (SFRC) base.

METHODS

Fifty sound maxillary premolars were divided randomly into 5 groups (n = 10); G1: Intact teeth (negative control), G2: Unrestored MOD cavities (positive control), G3: MOD inlay cavities restored with indirect lab composite, G4: MOD cavities restored with an SFRC base and microhybrid composite, and G5: MOD cavities restored with microhybrid composite. All specimens were thermocycled for 5000 cycles, then subjected to an axial static compressive load until fracture occurred. Failure modes were inspected.

RESULTS

Negative control group exhibited maximum fracture resistance, whereas positive control revealed the lowest (p < 0.05). Microhybrid composite restorations with an SFRC base demonstrated fracture thresholds not significantly different from indirect lab composite (p = 0.22); however, those without an SFRC base presented the least resistance to fracture among restored groups (p < 0.05). Cohesive failure of restorative material was mainly noted in the microhybrid composite group without an SFRC base, whereas adhesive failures were observed in all groups.

CONCLUSIONS

The resistance of teeth to fracture is significantly influenced by the restorative material. Under compressive loads, the teeth restored with microhybrid composite restorations incorporating a short fiber-reinforced composite base exhibited comparable fracture resistance to laboratory composite restorations.

CLINICAL SIGNIFICANCE

Considering that short fiber-reinforced composites revealed experimental outcomes comparable to those of indirect lab composites, along with the added benefits of shorter treatment time and cost-effectiveness, the direct approach becomes an ideal option for restoring teeth with Class II MOD cavities.