Reduction of Enterococcus faecalis in curved root canals after various sizes and tapers of canal preparation

Effects of increasing instrument size and taper on the disinfection and shaping of mandibular incisors

This study assessed canal preparation effects on disinfection and dentin preservation. Thirty mandibular incisors were paired into two experimental groups (n = 10). Following contamination, the initial microbial sample was collected. Instruments 30/0.03 (Group 1) and 30/0.05 (Group 2) were employed and a second sample was obtained. Canals were enlarged using instruments 40/0.03 and 40/0.05, respectively, and a third sample was collected. Final irrigation was performed, and sample S4 obtained. A final scan evaluated volume, surface area, unprepared areas, removed dentin and dentin thickness. Data were analysed using Student t-test, Mann-Whitney, Kruskal-Wallis and Dunn tests. A significant difference was observed between S1 and other time points (p < 0.05). Comparison between groups showed no differences in bacterial loads and in the percentage of microbial reduction (p > 0.05). Group 2 exhibited greater reduction in dentin thickness than group 1 in the mesial aspect of the root (p < 0.05). Instrument 30/0.03 might provide effective disinfection and safety during mandibular incisors canal preparation.

Impact of Different Access Cavity Designs and Ni–Ti Files on the Elimination of Enterococcus faecalis from the Root Canal System: An In Vitro Study

The present research aimed to reveal the in vitro effects of different endodontic file systems utilizing different endodontic access cavity designs on the elimination of Enterococcus faecalis from root canal systems. One hundred and fifty mandibular molar teeth were separated into three groups with respect to the access cavity design: traditional endodontic cavity (TEC), conservative endodontic cavity (CEC), and truss access cavity (TAC) (n = 50). After access cavity preparation, inolulation of teeth with E. faecalis was undertaken for 21 days. Following the first sampling (S1), further division of the groups into five subgroups (n = 10) was performed: ProTaper Gold, 2Shape, TruNatomy, Reciproc Blue, and WaveOne Gold. After instrumentation, bacterial sampling (S2) was performed. Bacterial reduction was evaluated in colony-forming units/mL, and statistical analysis was carried out. The E. faecalis count decreased significantly in all groups (p < 0.05). The range of mean values for a decrease in E. faecalis in log numbers was lowest in the TAC and Reciproc Blue groups, while the highest values of bacterial reduction were detected in the TEC and ProTaper Gold groups. The highest level of antibacterial action was obtained with the use of ProTaper Gold compared to the other file systems tested.

Micro-computed tomographic evaluation of the effect of the final apical size prepared by rotary nickel-titanium files on the removal efficacy of hard-tissue debris

Objective

This study was performed to compare the removal efficacy of hard-tissue debris in mandibular first molars prepared to various apical sizes.

Methods

The mesial root canals of 40 extracted mandibular first molars were prepared by rotary nickel-titanium files to an apical size of #25/0.04 (Group #2504), #30/0.04 (Group #3004), #35/0.04 (Group #3504), and #40/0.04 (Group #4004). Irrigation was performed with 5.25% NaOCl and 17% EDTA. Micro-computed tomography was used to scan the samples before and after root canal preparation. Remnant hard-tissue debris was identified, quantified, and visualized three-dimensionally using shape recognition and image superimposition analysis, and the debris was mapped to its location.

Results

After preparation, 11.67%±2.99% of the root canals contained hard-tissue debris in Group #2504, 8.00%±2.71% in Group #3004, 7.17%±2.88% in Group #3504, and 4.51%±1.61% in Group #4004. The amount of accumulated hard-tissue debris was significantly less in Group #4004 than in the other groups. However, there were no significant differences between Groups #3004 and #3504.

Conclusions

An increased final apical size resulted in significantly lower debris accumulation. However, no root canal in any group was completely free from hard-tissue debris, and debris was mostly found in the isthmus of the mesial root canals.

Comparative evaluation of Enterococcus faecalis counts in different tapers of rotary system and irrigation fluids: An ex vivo study

BACKGROUND

Bacteria and their by-products are etiological factors for the failure of endodontic treatment. Reduction of root canal bacterial contamination is one of the chief aims of root canal therapy. The aim of this study was to compare the effects of different rotary file tapers and two irrigation fluids on Enterococcus faecalis counts.

MATERIALS AND METHODS

In this ex vivo study Root canals of 72 human upper lateral incisors were enlarged to ISO #20 K-file. Then, the samples were sterilized and inoculated with E. faecalis for 72 h, divided into six experimental groups and prepared with #30 Flexmaster files with 0.02, 0.04, and 0.06 tapers and two different irrigation solutions such as normal saline and sodium hypochlorite. The control group (n = 10) was subdivided into two groups with or without bacterial inoculation and no mechanical instrumentation. Cleaning efficacy was evaluated in terms of the reduction of colony forming units (CFUs). T-test, ANOVA, Duncan, and Tukey tests were applied to the groups. A significant level of α = 0.05 was set for comparison between the groups.

RESULTS

The canals instrumented with 0.06 taper exhibited greater significant reduction in CFUs compared to canals instrumented with 0.04 and 0.02 taper (P < 0.05); 0.04 taper also resulted in greater significant reduction in CFUs than 0.02 taper (P < 0.05). In addition, no significant differences were observed in E. faecalis counts between the two irrigation fluids (P > 0.05).

CONCLUSION

Under the conditions of this study, root canal preparation with greater taper resulted in canal cleanliness and better debridement.

Assessment Using AutoCAD Software of the Preparation of Dentin Walls in Root Canals Produced by 4 Different Endodontic Instrument Systems

Objectives. To compare the effectiveness of four instrument systems for preparing oval root canals: manual instrumentation (Step-Back technique), ProTaper Universal, ProTaper Next, and Wave One. Material and Methods. For the purpose of this assessment, 60 teeth extracted for orthodontic or periodontal reasons, specifically canines and premolars with full coronal and root anatomy, were used and 15 samples were assigned to each group. The section of the canals was compared before and after instrumenting and the section of untouched canal wall was measured using AutoCAD software. The data was analysed by means of Shapiro-Wilk, ANOVA, and Kruskal-Wallis tests. Results. In the apical third, 100% of the canals were prepared with all the systems. In the middle third, a p value of 0.5989 in the Kruskal-Wallis test was obtained, which indicates no significant difference between the groups. At the coronal third level, the results obtained revealed that Wave One had a significantly lower mean average than the rest (p < 0.05). Conclusions. There are no differences between the various root canal instrument systems in the apical and middle thirds. At the coronal third level, Wave One system showed performance significantly worse than the rest, among which there were no differences.