Fracture patterns in endodontically treated teeth restored with or without horizontal fiber posts: An in vitro study

Endodontically treated maxillary premolars are more susceptible to fracture because of the loss of tooth structure following caries removal and endodontic procedures. Various composite restorative systems and reinforcement strategies, such as horizontal fiber posts (HFPs), have been proposed to improve fracture behavior and promote more favorable failure patterns.

The aim of this study was to evaluate fracture patterns in endodontically treated maxillary premolars restored with different composite systems, with and without horizontal fiber posts (HFP).

Sixty extracted maxillary premolars were prepared with standardized mesio-occlusal cavities and endodontically treated. Specimens were divided into six groups (n = 10) based on restorative material (Filtek Z350 XT, Multicore Flow, Smart Dentin Replacement (SDR)) and presence or absence of HFP. Horizontal slots were prepared for post placement in designated groups. Restorations were completed accordingly, and specimens were subjected to compressive loading using a universal testing machine. Fracture patterns were evaluated under a stereomicroscope and classified as adhesive/cohesive and favorable/unfavorable. Statistical analysis was performed using an unpaired t-test and one-way ANOVA (P < 0.05).

HFP groups showed a higher incidence of cohesive (0.70) and favorable fractures (0.70) compared to nonpost groups (0.50 and 0.40). Adhesive and unfavorable fractures were reduced in HFP groups. The differences were statistically significant (P = 0.019). SDR with HFP demonstrated the most favorable outcomes, although intermaterial differences were not significant (P > 0.05).

HFP significantly improve fracture patterns by promoting favorable and cohesive failures. Their reinforcing effect is more influential than the type of restorative material used.