RESUMO
(1) Background: The failure of nickel-titanium (NiTi) rotary files is a complication related to endodontic instruments. The aim of this study was to compare the resistance to cyclic fatigue between rotary and reciprocating file systems. (2) Methods: Specific PICO: Population (P): artificial root canals; Interventions (I): instrumentation with NiTi rotary and reciprocating files; Comparison (C): rotary versus reciprocating files; Outcome (O): cyclic fatigue resistance. Studies were identified through bibliographic research using electronic databases (Medline, Embase, Scopus, SciELO, and WOS). The studies were combined using a random effects model by the inverse variance method. The effect size was the mean of the time to fracture (TTF) and number of cycles to fracture (NCF). Heterogeneity was assessed using the p value of the Q test for heterogeneity and the I2. (3) Results: TTF for rotary files was determined in 474.5 s and 839.1 for reciprocating without statistically significant differences. NCF for rotary systems was determined in 1444.2 and for reciprocating file systems in 4155.9 with statistically significant differences (p = 0.035), making reciprocating files more resistant. (4) Conclusions: Reciprocating files have better resistance to cyclic fatigue than rotary files. When tested in double curvature canals, reciprocating files also showed higher resistance.
RESUMO
Aim: The aim of this study was to compare the cyclic fatigue strength of different reciprocating rotary systems depending on the movement used. Methods: Four study groups were analyzed (n = 30): (1) Reciproc®, (2) Reciproc Blue®, (3) Wave One Gold® and (4) Procodile®. Each group was divided into three subgroups according to the motion used: (A) Reflex Dynamic® (n = 10), (B) ReFlex Smart® (n = 10) and (C) conventional reciprocating motion (n = 10). They were used in a dynamic cyclic fatigue prototype until their fracture, and the time was measured in seconds. The results obtained were analyzed with the ANOVA method, and for two-to-two comparisons, the Tukey method and Weibull statistics were used. Results: Procodile ReFlex Smart had the longest time to failure, and statistically significant differences were found between Procodile ReFlex Smart and the other files and motions (p < 0.05). Conclusion: Smart motions increase cyclic fatigue strength. ReFlex Smart® motion increases the cyclic fatigue strength of reciprocating rotary systems, and Procodile® ReFlex Smart was the most resistant system file.
RESUMO
La técnica de bloqueo del nervio dentario inferior puede fallar entre un 44% y un 81% de las veces que se realiza en molares mandibulares con pulpitis irreversible aguda. Existen varias teorías que intentan explicar las causas por las que se produce este fenómeno, pero ninguna de ellas es capaz de aclarar de forma satisfactoria los mecanismos por los que se produce este fallo anestésico. El objetivo de esta revisión bibliográfica es repasar cada una de esas teorías y las soluciones que se han propuesto para el mejor manejo clínico de los pacientes en estas situaciones (AU)
The inferior alveolar nerve block can fail between 44% and 81% of the times that this technique is done in mandibular molars with irreversible pulpitis. There are several theories that attempt to explain the reasons why this phenomenon occurs, but none of them is able to satisfactorily clarify the mechanisms by which this anesthetic failure occurs. The aim of this review is to revisit each of these theories and the solutions that have been proposed for better clinical management of patients in these situations (AU)
