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Fracture resistance of endodontically treated premolars with optimum and overprepared post spaces

Khalid M Abdelaziz, Cinderella K Keshk, Omar S Al-Mashhour, Mohamed A Alhudairy, Mohamed S Asiri, Abdulla M Alshehri, Mohamed I Elshinawy


Background: Premolars are usually loss their integrity and strength following endodontic treatment. This situation necessitates the use of post-core-crown system at the time of tooth restorations; however, the criteria of post space preparation may affect the retention of the utilized posts and the resistance of the restored teeth to fracture. Aim: This study aims to evaluate the effect of post space preparation criteria on the fracture resistance of endodontically treated premolars. Materials and Methods: A total of 40 extracted single-rooted premolars were subjected to endodontic treatment after cutting their crowns 2 mm above the cervical line. Root canals in Group 1 (n = 20) were optimally prepared to receive #2 fiber post (Relyx fiber post), while those in Group 2 (n = 20) were overprepared using #3 drill to receive the same size of posts. All posts were fixed into their respective spaces using self-adhesive resin cement (RelyX Unicem) before building resin composite cores up. Additional 20 premolars with no endodontic treatment served as control. All teeth were then prepared to receive standardized zirconia-based crowns. The fracture resistance of teeth in each group was evaluated on a universal testing machine before and after store aging and thermocycling. Both ANOVA and Tukey’s comparisons at α = 0.05 were used to statistically analyze the results. Results: All endodontically treated teeth fractured at lower stress values than non-treated teeth (P < 0.05). Teeth with over prepared post spaces fractured at lower stress values than those with optimally prepared post spaces (P = 0.0001382 and 0.000138). Non-aged teeth in all groups showed more resistance to fracture than aged ones (P = 0.0001382, 0.0001386, and 0.0001424). Signs of catastrophic tooth fracture were seen in most of the tested specimens. Conclusion: Although all restoration options provide premolars resistant to fracture under regular masticatory values, their resistance is decreased by aging. Over preparation of post spaces results in lower resistance of the restored teeth to fracture on loading. Clinical Significance: Because endodontically treated teeth, even those restored with post-core-crown systems, usually show a reduction in their fracture resistance by age, dentists should utilize the most conservative techniques while restoring these kinds of teeth.


Fiber post; fracture resistance; post space; premolars; self-adhesive cement; zirconia crowns

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