Comparing Fracture Resistance and Mode of Failure of Giomer Versus Alkasite Restorative Materials in Grossly Carious Primary Incisors: An In-vitro Study

objective: This study aimed to evaluate and compare the fracture resistance and failure modes of severely damaged primary maxillary incisors restored using Giomer (Beautifil-Bulk Fill) and Alkasite (Cention Forte) as intracanal restorative materials. Materials and Methods: Twenty extracted maxillary primary incisors with similar dimensions were decoronated 1 mm above the cementoenamel junction (CEJ) to simulate extensive coronal destruction. After standard root canal preparation and obturation with Metapex, post spaces were prepared and restored with either Giomer (Group I) or Cention Forte (Group II) following manufacturers’ instructions. All specimens underwent 5000 thermocycles to simulate intraoral thermal aging. Fracture resistance was measured using a universal testing machine at a 148° angle to the palatal surface until failure. Failure modes were examined under a 25x stereomicroscope and categorized as repairable (above CEJ) or irreparable (below CEJ). Statistical analysis was performed using SPSS (version 24), with significance set at p ≤ 0.05. Results: Group I (Giomer) exhibited a mean fracture resistance of 211.46 ± 88.04 N, while Group II (Cention Forte) showed 191.12 ± 90.3 N, with no statistically significant difference between groups (p = 0.616). The failure mode was predominantly irreparable in both groups (60% in Giomer, 70% in Cention Forte), with no significant difference (p = 0.639). No correlation was found between fracture resistance and failure mode in either group. Conclusion: Both Giomer and Cention Forte provided comparable mechanical reinforcement for restoring grossly carious primary anterior teeth. However, the high incidence of irreparable fractures suggests the need for improved reinforcement strategies.