Int Endod J. 2022 Jan;55(1):103-112. doi: 10.1111/iej.13635. Epub 2021 Oct 21.

Influence of conservative endodontic access cavities on instrumentation of oval-shaped straight root canals.

International endodontic journal

Ana Raquel Lopes Dos Santos Miranda, João Daniel Mendonça de Moura, Pedro Henrique Souza Calefi, Pablo Andrés Amoroso Silva, Marilia Fagury Videira Marceliano-Alves, Ricardo Tadeu Lopes, Rodrigo Ricci Vivan, Patrícia de Almeida Rodrigues

PMID: 34561894 DOI: 10.1111/iej.13635

Abstract

AIM: To evaluate the influence of the design of endodontic access cavities on the percentage of unprepared areas of canal walls and flexural fatigue of instruments activated by reciprocating movement in oval-shaped straight root canals of extracted teeth.

METHODOLOGY: Forty-two mandibular incisors with oval canals were scanned by a microcomputed tomography (micro-CT) device for homogeneous selection and distribution of the samples. Then, the teeth were divided into two groups (n = 21) according to the design of access cavity being tested: ultraconservative endodontic access cavity (UltraAC) and traditional access cavity. The canals were accessed with the aid of a surgical microscope, instrumented with the WaveOne Gold Medium system and irrigated with 2.5% NaOCl and 17% EDTA. The unprepared areas of the canal wall were analysed by overlaying images before and after instrumentation and expressed as percentages. micro-CT data were analysed using t-test, Mann-Whitney and Wilcoxon tests. The endodontic instruments used during instrumentation were subjected to static flexural fatigue testing using an artificial stainless steel canal with a 60° angle of curvature and a radius of 5 mm, located 5 mm from the tip of the instrument. The instruments were activated until fracture occurred, and the time in seconds for the fracture was recorded using a digital timer. The number of cycles to fracture was calculated and analysed statistically. For flexural fatigue data, an anova test complemented by a Tukey range test was used. The significance level of 5% was used for all analyses.

RESULTS: There was no significant difference between the groups related to unprepared areas by the instrument during canal preparation (p > .05). The difference in flexural fatigue resistance between the groups was not significant.

CONCLUSION: The use of UltraAC did not interfere with the canal instrumentation of extracted mandibular incisors with straight and oval canals. There was no difference in the flexural fatigue resistance of the instruments in relation to access cavity design.

© 2021 International Endodontic Journal. Published by John Wiley & Sons Ltd.

Keywords: conservative access; flexural fatigue; instrumentation; micro-CT; oval-shaped

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Publication Types

• Journal Article

Grant support

• Nuclear Instrumentation Laboratory of the Alberto Luiz Coimbra Institute for Graduate Studies and Research in Engineering of the Federal University of Rio de Janeiro.