Influence of apical preparation size and irrigation technique on root canal debridement: a histological analysis of round and oval root canals

Abstract

Aim To examine the debridement of round and oval root canals prepared to two apical sizes with and without ultrasonically activated irrigation. Methodology Mandibular premolars with round (n = 48) and oval (n = 48) root canals were pair‐matched after microCT scanning and randomly divided into two experimental groups (n = 20): group 1, rotary NiTi to size 20, .04 taper; group 2, rotary NiTi to size 40, .04 taper. Specimens were subdivided into two subgroups (n = 10): subgroup A, syringe and needle (SNI); subgroup B, ultrasonically activated irrigation (UAI). Untreated canals (eight oval and eight round) served as controls. Specimens were processed for histological evaluation for measurement of the remaining pulp tissue and debris (RPT), and the perimeter percentage of root canal area untouched by the instruments (PRAU). Following assessment of normality, multiple‐way anova models were used to study the effects of preparation size, irrigation technique and canal cross‐sectional shape, and their interactions on the RPT and PRAU (α = 0.05). Results All experimental groups had significantly less RPT than the control (P < 0.05). Both the preparation size (20 vs. 40) and the irrigation technique (SNI vs. UAI) had a significant effect on RPT (P = 0.006 and P < 0.001, respectively). Groups irrigated with SNI always had significantly greater RPT than those irrigated with UAI, irrespective of the preparation size (P < 0.001). Canals prepared to size 20 had significantly greater RPT than those with size 40 in the SNI subgroup (P < 0.001), but there was no significant difference in the UAI subgroup (P = 0.481). Conclusions Root canals prepared to a larger size (40) were cleaner than those prepared to a smaller size (20), when irrigation was performed with a syringe and needle. When the irrigant was ultrasonically activated, smaller preparations resulted in canals that were as clean as larger preparations. This finding was common to both round and oval canals of freshly extracted premolars with vital pulp tissue.

Creation of well‐balanced experimental groups for comparative endodontic laboratory studies: a new proposal based on micro‐CT and in silico methods

“…Basically, these methods aimed to allocate samples into experimental groups according to their anatomical characteristics. It was observed that some studies adopted one point of the root, usually 5 mm from the anatomical apex, and measure the width of the root canal in both buccal and proximal directions, following the methodology of Wu et al (2000), to determine its shape (Tinoco et al 2014, Teixeira et al 2015, Lee et al 2019). In other studies, specimens are allocated from the same group of teeth by randomization (Topçuoğlu et al 2016, Silva et al 2017, Pedullà et al 2019), whilst some of them adopted a combination of radiographic and randomized methods to form pairs (Ruckman et al 2013, Bernardes et al 2016).…”

Effect of Sonic Agitation of a Binary Mixture of Solvents on Filling Remnants Removal as an Alternative to Apical Enlargement—A Micro-CT Study

“…Additionally, root canals prepared to a larger size (size 40) were as clean as smaller preparations (size 30) after the sonically agitated solvent mixture. Accordingly, it was recently reported that when sodium hypochlorite was ultrasonically activated, smaller preparations resulted as clean as larger preparations [ 28 ]. Even though the referenced study evaluated the remaining pulp tissue and debris instead of residual filling materials, the results demonstrate the influence of the irrigation strategy overcoming the insufficiencies of the instrumentation approach, irrespective of the canal configuration (round vs. oval).…”

Current Trends in the use of Irrigant Activation Techniques among Endodontist & Post graduates in India - a Knowledge, Attitude and Practice based survey

“…One randomised clinical trial found that ultrasonic activation in straight canals with periapical lesions did not result in a superior clinical outcome when compared with needle irrigation ( 29 ). But a recent in vitro study showed a compelling evidence of the increased efficacy of PUI in root canals with minimal preparation ( 30 ). Other in vitro studies comparing an individual IAT with syringe irrigation proved superiority, ( 13 , 14 , 24 ).…”