Effect of Preparation Design on Fracture Resistance and Mode of Failure of Advanced Lithium Disilicate Glass Ceramic versus Hybrid Ceramic Endocrowns on Premolars (In-Vitro Study)

Document Type : Original Article

Authors

1 Lecturer of Fixed Prosthodontics, Faculty of Dentistry, Cairo University

2 Associate professor of Fixed Prosthodontics, Faculty of Dentistry, Cairo University and School of Dentistry, Newgiza University

Abstract

Objective: To evaluate fracture resistance and failure modes of advanced lithium disilicate and hybrid ceramic endocrowns with butt joint versus ferrule marginal preparations on endodontically treated maxillary premolars.
Materials and Methods: Forty extracted human maxillary premolars were endodontically treated and randomly allocated into four groups (n=10): Group FT and BT advanced lithium disilicate (Cerec Tessera) with ferrule and butt joint preparation designs, Group FC and BC hybrid ceramic (Cerasamrt) with ferrule and butt joint preparation designs. Endocrowns were CAD/CAM fabricated and cemented with dual-cure resin cement. Following thermocycling (5,000 cycles), specimens underwent compressive loading until fracture. Fracture resistance (N) was analyzed using one-way ANOVA with Tukey's post-hoc test. Failure modes were evaluated by stereomicroscopy and analyzed using Fisher's Exact test (P ≤ 0.05).
Results: Group BT demonstrated significantly highest fracture resistance (1772.7 ± 38.61 N), followed by BC (1161.64 ± 54.26 N), FC (1082.87 ± 46.48 N), and FT (970.66 ± 32.33 N) (p<0.0001). Failure mode analysis revealed 35% favorable failures overall, with BC group showing 100% favorable failures and FT group showing 100% unfavorable failures.
Conclusions: Both materials and preparation designs demonstrated clinically acceptable fracture resistance values. Material-preparation compatibility significantly influences endocrown performance. Advanced lithium disilicate with butt joint preparation is recommended for maximum fracture resistance, while hybrid ceramic with butt joint preparation may be preferred when favorable failure modes are prioritized.

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Egyptian Dental Journal
Volume 71, Issue 3 - Serial Number 4
Fixed Prosthodontics, Removable Prosthodontics and Dental Materials
July 2025
Pages 2531-2542

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