Assessment of canal walls after biomechanical preparation of root canals instrumented with Protaper Universal rotary system

Assessment of Biomechanical Preparation Influence on Various Root Canal Curvatures

Aim

To determine the influence of biomechanical preparation on various parameters of root canal curvature.

Materials and methods

A total of 72 tooth roots with moderate (10-25°) and severe canal curvature (26-75°) were selected and embedded in autopolymerizing acrylic resin for which cone-beam computed tomography (CBCT) image analysis was performed. Schneider angle, canal access angle (CAA), and the radius of curvature were determined preoperatively using auto-computer-aided design (CAD) 2021 software. Protaper gold rotary nickel-titanium (Ni-Ti) files were used to prepare the root canals. All angular and linear values were measured in auto-CAD and compared using postoperative CBCT pictures. The difference in pre- and postoperative values was assessed using paired samples t-test and independent samples t-test.

Results

There was a statistically significant difference between the Schneider angle (p = 0.002), (p < 0.001), CAA (p < 0.001), (p = 0.001), and radius of curvature (p = 0.01), (p = 0.001) pre- and postoperatively in both moderate and severe canal curvature groups, respectively. This difference was greater in the severe curvature group (p-value = 0.027) than in the group exhibiting moderate curvature. Among the parameters tested, Schneider angle has shown maximum difference pre- and post before and after mathematical processing (BMP) compared to other parameters.

Conclusion

This approach is a new and objective way of measuring root canal geometric changes. The current findings suggest that the Schneider angle, CAA, and the radius of curvature can be used as parameters to evaluate the changes in canal geometry following biomechanical preparation.

How to cite this article

Nekkanti H, Enuganti S, Avula JSS, et al. Assessment of Biomechanical Preparation Influence on Various Root Canal Curvatures. Int J Clin Pediatr Dent 2024;17(2):130-135.

Sealability of Different Root Canal Nanosealers: Nano Calcium Hydroxide and Nano Bioactive Glass

Background:

The success of the endodontic treatment is largely dependent on the sealing achieved by root canal obturation. The application of sealer fills imperfections and increases adaptation of the root filling to the canal walls.

Aim:

To evaluate the sealability of experimental nanosealers (nano calcium hydroxide and nano bioactive glass) and to compare it with the commercial zinc oxide eugenol sealer using a dye penetration method.

Materials and Methods:

Sixty single-rooted mandibular premolars were selected. The tooth crowns were removed so as to obtain standardized 15-mm-long root specimens. The root canal was instrumented with Protaper Ni-Ti rotary file and the final file size was up to # F4/.06 (in vitro study). They were then randomly allocated into 3 groups of 20 specimens each (n=20) according to the sealer used for obturation, and all samples were filled with single cone gutta-percha (#40/06) and one of the tested sealers. All teeth were coated with nail polish and then suspended in 2% methylene blue dye for 7 days. Stereo-microscope (x10) was used to evaluate the sealability of newly introduced nanosealers. The data were statistically analyzed by ANOVA test followed by post hoc analysis (P < 0.05).

Results:

Significant improvement shown by the presented study suggests that nano calcium hydroxide sealer showed significantly less dye leakage than nano bioactive glass sealer and zinc oxide eugenol sealer.

Conclusion:

The results of this study showed that the synthesized nano-powder sealers are suitable for use in root canal therapy to prevent leakage.

The root canal can be sealed better by using smaller nano-powder particle sizes. In addition, the two groups exhibited significant differences in leakage in comparison with commonly used ZOE sealer.

Impact of Different Irrigant Agitation Methods on Bacterial Elimination from Infected Root Canals

Activation techniques are essential for root canal disinfection but may result in incomplete removal of bacteria. The aim of our study was to assess the antibacterial action of sonically, ultrasonically and laser-activated irrigation and 5.25% sodium hypochlorite (NaOCl) on Enterococcus faecalis in an infected tooth. Forty-four extracted mandibular premolars were mechanically prepared, sterilized, and inoculated with E. faecalis for 1 week. Bacterial counts after inoculation were evaluated in 4 randomly chosen teeth, remaining root canals were divided into 4 groups. Group A: laser-activated irrigation by photon-induced photoacoustic streaming, Group B: the sonic irrigation by EDDY, Group C: ultrasonic irrigation by EndoUltra, and Group D: 5.25% NaOCl. Colony forming unit (CFU) counts were measured and Kolmogorov-Smirnov, Wilcoxon, Kruskal-Wallis and Mann-Whitney tests were used to determine differences. The mean of CFU was found to significantly decrease in group D, 2110 ± 1015.93 (p < 0.001). Changes in measurement levels followed the same trend over time in groups A 27.40 ± 30.15, B 81.3 ± 85.68 and C 44.40 ± 67.12 (p = 0.141). The average CFU after irrigation in all groups was significantly greater than 0. Within the limitations of this study, all activation techniques were superior to NaOCl 5.25% in reducing E. faecalis from the infected tooth model.

Apical dye leakage of two single-cone root canal core materials (hydrophilic core material and gutta-percha) sealed by different types of endodontic sealers: An in vitro study

Aim of the Study:

The aim of this study was to compare the apical sealing ability of two single-cone filling materials when sealed with different types of root canal sealers.

Materials and Methods:

Eighty extracted maxillary and mandibular canines were selected and their crowns were cut. The root canals were prepared using ProTaper Universal rotary system until size F4 and then divided into seven experimental groups (n = 10 each) and two control groups (n = 5 each). Samples of Groups 1, 2, and 3 were filled with single-cone gutta-percha and AH Plus, MTA Fillapex, and EndoSequence BC, respectively. Samples of Groups 4, 5, and 6 were filled similar to the previous groups with the exception of using a single-cone CPoint. Samples of Group 7 were filled with cold gutta-percha lateral condensation technique. To assess apical microleakage, the apical linear dye penetration was measured microscopically and data were statistically analyzed.

Results:

All experimental groups showed significantly different dye apical leakage values (P = 0.000). No significant differences were found between Groups 1, 2, 4, 6, and 7 (P < 0.05). The lowest mean leakage value was observed in Group 6 (0.95 ± 0.56 mm) while Groups 3 (2.68 ± 0.71 mm) and 5 (2.61 ± 0.71 mm) showed significantly higher mean leakage values.

Conclusions:

The lowest apical leakage value was observed with single-cone CPoint/EndoSequence BC but without significant differences when compared with single-cone gutta-percha/AH Plus, single-cone gutta-percha/MTA Fillapex, single-cone CPoint/AH Plus, and lateral condensation technique. Higher apical leakage values were observed with single-cone gutta-percha/EndoSequence BC and CPoint/MTA Fillapex.

Assessment of the Centralization of Root Canal Preparation with Rotary Systems

OBJECTIVE

Apical deviations are important factors in endodontic therapy, since they can cause the treatment failure. The aim of the present study was to determine the centering capacity of ProTaper Universal™, Twisted File™ and Revo-S^® rotary systems using cone beam computed tomography analysis before and after the instrumentation of root canals.

MATERIALS AND METHODS

Thirty mesiobuccal roots from human lower first molars were divided into three groups of ten: Group 1 - ProTaper Universal™ Rotary System; Group 2 - Twisted File™ Rotary System; and Group 3 - Revo-S^® Rotary System. All teeth were scanned using computed tomography to determine the condition of the root canal before and after instrumentation (4mm, 3mm and 2mm from the root apex). Images were made using ICAT VISION software for both instrumented and non-instrumented canals.

RESULTS

The results were analyzed statistically using the Kolmogorov-Smirnov normality test for quantitative variables. Comparisons were made with two groups (Mann-Whitney - abnormal) and with more than two groups (Kruskal Wallis - abnormal). The level of significance was set at p<0.05. A statistically significant difference was found for the measurement of 4 mm between the "ProTaper Universal" and "Twisted File" systems. For the Twisted File system, a statistically significant difference was recorded between the measurements of 4mm and 3 mm.

CONCLUSION

None of the assessed instruments was completely effective in terms of the biomechanical preparation of root canals since all created deviation from the original anatomy of the canal.

Apical transportation associated with ProTaper Universal F1, F2 and F3 instruments in curved canals prepared by undergraduate students

Objective

This study evaluated apical transportation associated with ProTaper^® Universal Fl, F2 and F3 rotary files in curved canais prepared by undergraduate students.

Material and Methods

Twenty mesial roots of mandibular molars with curvatures ranging between 25° and 35° were selected. Mesiobuccal canals were instrumented by twenty students with the ProTaper^® system (Dentsply-Maillefer, Ballaigues, Switzerland) according to the manufacturer's instructions. Pre-fiaring was performed with Sl and SX files. A #15 K-file was inserted into the root canal up to the working length (WL), and an initial digital radiograph was taken in a buccolingual direction (baseline). Afterwards, the S1, S2, F1, F2, and F3 files were employed up to the WL. Other radiographies were taken in the same orientation of the baseline after the use of the Fl, F2, and F3 files, with each file inserted into the root canal. The radiographic images were overlapped, and the Image J software was used to measure the distance between the rotary files' ends and the #15 K-file's end, characterizing the apical transportation. Data were analyzed by Repeated Measure ANOVA and by the SNK post hoc test (P<0.05).

Results

It was verified that file size affected apical transportation significantly (P<0.001). The F3 file showed higher apical transportation than Fl and F2, while between these last files there was no difference.

Conclusion

The undergraduate students produced lower apical transportation in curved canals when they did not use the F3 rotary file.

Wizard CD Plus and ProTaper Universal: analysis of apical transportation using new software

OBJECTIVE

This study has two aims: 1) to evaluate the apical transportation of the Wizard CD Plus and ProTaper Universal after preparation of simulated root canals; 2) to compare, with Adobe Photoshop, the ability of a new software (Regeemy) in superposing and subtracting images.

MATERIAL AND METHODS

Twenty five simulated root canals in acrylic-resin blocks (with 20º curvature) underwent cone beam computed tomography before and after preparation with the rotary systems (70 kVp, 4 mA, 10 s and with the 8×8 cm FoV selection). Canals were prepared up to F2 (ProTaper) and 24.04 (Wizard CD Plus) instruments and the working length was established to 15 mm. The tomographic images were imported into iCAT Vision software and CorelDraw for standardization. The superposition of pre- and post-instrumentation images from both systems was performed using Regeemy and Adobe Photoshop. The apical transportation was measured in millimetres using Image J. Five acrylic resin blocks were used to validate the superposition achieved by the software. Student's t-test for independent samples was used to evaluate the apical transportation achieved by the rotary systems using each software individually. Student's t-test for paired samples was used to compare the ability of each software in superposing and subtracting images from one rotary system per time.

RESULTS

The values obtained with Regeemy and Adobe Photoshop were similar to rotary systems (P>0.05). ProTaper Universal and Wizard CD Plus promoted similar apical transportation regardless of the software used for image's superposition and subtraction (P>0.05).

CONCLUSION

Wizard CD Plus and ProTaper Universal promoted little apical transportation. Regeemy consists in a feasible software to superpose and subtract images and appears to be an alternative to Adobe Photoshop.

Sealability of MTA and calcium hydroxidecontaining sealers

Objectives

The aim of this study was to evaluate the apical sealability of Fillapex^®, Endo-CPM-Sealer^® and Sealapex^®.

Material and Methods

Ninety-four freshly extracted single-rooted teeth were selected and decoronated. All teeth were radiographed to confirm the existence of a single and straight root canal, which was prepared using Protaper Universal and 2.5% sodium hypochlorite. The teeth were randomly divided in groups of 10 specimens each according to the sealer, and the canals were filled using the single cone technique and one of the sealers. Four additional teeth were used as controls. The teeth were submitted to dye leakage with Rhodamine B for 24 h but using vacuum on the initial 15 min. Thereafter, they were cut longitudinally and the leakage was measured in a linear fashion from apex to crown. Data were analyzed by ANOVA and Tukey's tests at 5% significance level.

Results

Fillapex^® and Sealapex^® showed significantly less dye leakage than Endo-CPM-Sealer^® (p<0.05).

Conclusions

It was concluded that Fillapex^® and Sealapex^® were able to prevent apical dye leakage differently from Endo-CPM-Sealer^®.

Comparison of debris extruded apically and working time used by ProTaper Universal rotary and ProTaper retreatment system during gutta-percha removal

Objective

The aim of this study was to evaluate the in vitro action of ProTaper retreatment files and ProTaper Universal in the retreatment of mandibular premolars.

Material and methods

The amount of debris extruded apically was measured and the time to reach the working length and to complete the removal of gutta-percha was observed. Thirty teeth had their canals prepared using ProTaper Universal files and were obturated by the single cone technique. The teeth were then stored at 37ºC in a humid environment for 7 days. During the use of the rotary instruments for root canal filling removal, the apical portions of the teeth were attached to the open end of a resin tube to collect the apically extruded debris.

Results

ProTaper Universal files were significantly faster (p=0.0011) than the ProTaper retreatment files to perform gutta-percha removal, but no significant difference was found between the files regarding the time to reach the working length or the amount of apical extrusion.

Conclusions

ProTaper Universal rotary had better results for endodontic retreatment, and both techniques promote similar apical extrusion of debris.

Comparison of the centring ability of the ProTaper™ and ProTaper Universal™ rotary systems for preparing curved root canals

The aim of this in vitro study was to compare the centring ability of the ProTaper™ and ProTaper Universal™ rotary systems for preparing curved root canals, by means of preoperative and postoperative imaging of a cross-section of their coronal, middle and apical thirds. Twenty mesiobuccal root canals of human mandibular first molars with a degree of curvature ranging from 55° to 60° were randomly divided into two groups of 10 specimens each: Group 1, ProTaper™ rotary system; and Group 2, ProTaper Universal™ rotary system. The data were analysed statistically by Kruskal-Wallis and Student's t-test at the 5% significance level. The results showed that the differences between the percentages of the presence of deviation observed were not statistically significant. Both systems showed the capacity for producing centred preparations in curved root canals with low proportions of deviation.