Influence of Endodontic Treatment and Retreatment on the Fatigue Failure Load, Numbers of Cycles for Failure, and Survival Rates of Human Canine Teeth

• Published in: Journal of endodontics Vol. 43; no. 12; pp. 2081 - 2087
• Main Authors: Missau, Taiane, De Carlo Bello, Mariana, Michelon, Carina, Mastella Lang, Pauline, Kalil Pereira, Gabriel, Baldissara, Paolo, Valandro, Luiz Felipe, Souza Bier, Carlos Alexandre, Pivetta Rippe, Marília
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01-12-2017
• Subjects: Cuspid; Dental Stress Analysis; Dentistry; Endodontic treatment; fatigue resistance; Humans; In Vitro Techniques; Random Allocation; Retreatment; Root Canal Therapy; Treatment Failure; vertical root fracture; Endodontic treatment; vertical root fracture; fatigue resistance; retreatment
• ISSN: 0099-2399; 1878-3554
• DOI: 10.1016/j.joen.2017.07.013

This study evaluated the effects of endodontic treatment and retreatment on the fatigue failure load, numbers of cycles for failure, and survival rates of canine teeth.
Sixty extracted canine teeth, each with a single root canal, were selected and randomly divided into 4 groups (n = 15): untreated, teeth without endodontic intervention; prepared, teeth subjected only to rotary instrumentation; filled, teeth receiving complete endodontic treatment; and retreated, teeth retreated endodontically. After the different endodontic interventions, the specimens were subjected to fatigue testing by the stepwise method: 200 N (× 5000 load pulses), 300 N, 400 N, 500 N, 600 N, 800 N, and 900 N at a maximum of 30,000 load pulses each or the occurrence of fracture. Data from load to failure and numbers of cycles for fracture were recorded and subjected to Kaplan-Meier and Log Rank tests (P < .05), in addition to Weibull analysis. The fractures of the specimens were classified as repairable or catastrophic.
The retreated, filled, and untreated groups presented statistically significantly higher fatigue failure loads and numbers of cycles for failure than did the prepared group. Weibull analysis showed no statistically significant difference among the treatments for characteristic load to failure and characteristic number of cycles for failure, although, for number of cycles, a higher Weibull modulus was observed in filled and retreated conditions. The predominant mode of failure was catastrophic.
Teeth subjected to complete endodontic treatment and retreatment behaved similarly in terms of fatigue failure load and number of cycles to failure when compared with untreated teeth.
•Predominant mode of failure of canines subjected to fatigue was catastrophic fracture.•Filled, retreated, and untreated teeth presented a similar fatigue resistance.•There was no statistical difference among the Weibull moduli of the load of failure.