Curvature height and distance of MB canal of mandibular molar with Schneider angle and its comparison with canal access angle

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.

Comparison of smear layer removing efficacy of Cold Atmospheric Pressure (CAP) Plasma Jet with different chelating agents. An ex-vivo study

The present study aimed to assess the effectiveness of different final irrigation regimens (Cold Atmospheric Pressure Plasma Jet, MTAD, and EDTA) in removing the smear layer from intra-radicular dentin using a Scanning Electron Microscope (SEM). Eighty-four mandibular premolars were prepared with ProTaper Universal hand files and were equally divided into four groups i.e. Normal saline (control), EDTA, MTAD and CAP Plasma Jet. Prepared samples in the control, EDTA and MTAD groups were irrigated with 5 milliliters of the irrigant, and it was retained for 2 min. In the CAP Plasma Jet group, the plasma plume was directed towards the canal lumen for 2 min. The smear layer removal of all the groups was evaluated at the coronal, middle and apical thirds. Statistical analysis was performed using Kruskal-Wallis test followed by Dunn's test. Evaluation by SEM showed that the smear layer removal ability of MTAD and EDTA were significantly better than CAP Plasma Jet (p < 0.05). While CAP Plasma Jet showed results comparable to EDTA in the coronal third. In the middle and apical third of the canal, its effect was comparable to the control group (p > 0.05). MTAD and EDTA aided in better smear layer removal than the CAP Plasma Jet in the coronal, middle, and apical third of the test samples. CAP Plasma jet performed better in the coronal third.

Cone-Beam Computed Tomography Evaluation of Rotary MM Files vs Manual K Files in Primary Molars: An In Vitro Study

AIM

Rotary instrumentation in pediatric dentistry is an emerging concept, thus this study was performed to evaluate the remaining dentine thickness (RDT), canal transportation, centering ability, quality of obturation using cone-beam computed tomography (CBCT), and the time efficiency of rotary versus manual instrumentation in mandibular second primary molars.

MATERIALS AND METHODS

Forty mandibular primary second molars (160 canals) were randomly and equally allocated to four groups. Instrumentation was done using K files in groups I and II; in each group, the obturation was done by two different obturation techniques; incremental technique and disposable syringe technique, respectively. MM rotary files (Innovative Material and Devices, Inc. [IMD], Shanghai, China) were used in groups III and IV; in each group, the obturation was done by incremental technique and disposable syringe technique. Preoperative and postoperative CBCT scans were performed and evaluated for the RDT, centering ability, canal transportation, and the canal filling quality, which was assessed as (underfill, optimal fill, and overfill). Instrumentation time was recorded for groups I and II collectively (manual instrumentation), and groups II and III collectively (rotary instrumentation). Statistical analysis was done using Chi-square, ANOVA, and post hoc Tukey tests, at p < 0.05).

RESULTS

The MM rotary file removed a significantly less amount of dentine at all levels specifically at the middle section (p = 0.003). The canal transportation was significantly higher in the manual group at the cervical level (p = 0.022). In all sections, the rotary group had significantly higher values of centering ratio than the manual group (p < 0.05), which means a lower deviation of rotary instruments. For both types of files, there was no significant difference between different obturation techniques (p > 0.05). Instrumentation time was significantly lower in the rotary group (p < 0.001).

CONCLUSION

Regarding the dentine removal and the shaping ability of MM files acceptable results were obtained; however, no significant difference between the different obturation techniques. Notable time efficiency was reported in the rotary files as well.

CLINICAL SIGNIFICANCE

The use of rotary files resulted in better conservation of tooth structure, better canal centering, and obturation quality as well as less canal transportation and less instrumentation time compared to manual K files.

Analysis of Shaping Abilities of Rotary File Systems in Oval Canals with Moderate Root Curvature: A Randomized Controlled Ex Vivo Study

AIM

The purpose of this study was to evaluate and compare the canal transportation tendencies and centering ability of the TruNatomy shaper (TN) and XP-endo shaper (XPS) rotary systems in oval-shaped canals with moderate root curvature (15°-25°), using cone-beam computed tomography (CBCT) imaging.

MATERIALS AND METHODS

Sixty single-rooted permanent human teeth were chosen after considering the inclusion and exclusion criteria. The teeth were divided into two groups (n = 30). The test group was instrumented with TN files and the other with XPS according to manufacturer's instructions. CBCT images were taken before and after instrumentation to record the root canal distances from mesial, distal, buccal, and lingual borders of the root at 3, 5, and 7 mm distances from the root apex using a specific formula. Statistical analysis was done using the Statistical Package for the Social Sciences software program, version 20.0. The data were analyzed using the unpaired t test.

RESULTS

Both TN and XPS were safe for use in oval-shaped canals with moderate root curvature. However, the XPS showed higher buccolingual transportation as compared with TN at 3 mm from the apex and higher mesiodistal transportation at 3 and 5 mm levels from the apex as compared with TN.

CONCLUSION

Canal transportation has been detected in both systems; however, the values obtained were within the safe range (<0.3 mm). Overall, no significant difference was observed between TN and XPS (p > 0.05) in their canal transportation tendencies and centering ability.

CLINICAL SIGNIFICANCE

The study assesses the canal centering and transportation tendencies of the recently launched TN rotary system in extracted teeth with a combination of morphologies. The findings of the study are significant clinically as minimum transportation of the canal, minimal dentin removal, efficient disinfection, and three-dimensional obturation of the root canal are considered important factors in deciding the prognosis of endodontic therapy.

The Evaluation of Debris and Smear Layer Generated by Three Rotary Instruments Neo NiTi, 2Shape and Revo_S: An Ex-vivo Scanning Electron Microscopic Study

Introduction

This study compared the cleaning effectiveness of NeoNiTi, 2Shape and Revo_S rotary instruments.

Materials and Methods

Fifty mandibular molar mesial roots were selected with an angle of curvature less than 20 degrees divided into three groups (n=15). Five samples were selected as negative control group. In all three systems, the final file was 25, 6%. The score of debris and smear layer in three thirds (coronal, middle and apical) of the root canal walls were evaluated using scanning electron microscopic (SEM) magnification. The data were analyzed using the Kruskal Wallis and Mann Whitney U tests for intergroup comparison (P≤0.05) and Freidman and Wilcoxon signed-rank test was employed for intragroup comparison (P≤0.05).

Results

Residual debris of the 2Shape system in the apical region was significantly higher than the other two systems (P=0.039). Revo_S and 2Shape groups had significantly higher quantities of debris in the apical than the coronal region (P=0.029 and P=0.02, respectively). In the 2Shape group, the amount of mid-region debris was significantly higher (P=0.005) than the coronal. In inter-group comparison there was no significant difference in residual smear layer between the systems. In intra-group comparison in all three systems, the amount of smear layer in the coronal third was significantly higher than in the other two areas. (P=0.017, P<0.001 and P=0.032, respectively).

Conclusion

2Shape left the highest amount of debris in the apical region. The amount of debris in Revo_S and 2Shape groups in the apical region was significantly higher than in the coronal. The amount of smear layer in all three groups in the coronal area was higher than the middle and apical areas.

Evaluation of dentinal crack propagation, amount of gutta percha remaining and time required during removal of gutta percha using two different rotary instruments and hand instruments - An In vitro study

Background

One of the most important goal of non surgical endodontic retreatment is the successful removal of gutta percha and sealers from the root canal system. A variety of techniques have been recommended for retreatment procedures for the removal of gutta-percha and sealers with or without the help of adjunctive chemical solvents, by using stainless steel hand files or nickel-titanium rotary files, gate glidden burs, heated instruments, ultrasonic instruments, and lasers 1,3. The current advancements in the design of NiTi instruments have proved efficacious in the removal of filling materials from the root canal wall and various studies have also confirmed their cleaning ability and efficacy 4,5. Nevertheless, the use of rotary instrumentation can lead to the formation of dentinal cracks in the root canal dentin. Many researchers have reported the incidence of crack formation and propagation after the procedure with manual, rotary and reciprocating instruments. The behavior of rotary instruments in the generation of defects have been the point of greatest interest during many years 6. These dentinal cracks can be defined as defects with a complete crack line extending from inner root canal space up to the outer surface of the root when the tensile stress in the root canal wall exceeds the tensile stress of dentin 7.

Aim

This study was conducted to investigate and to compare the amount of dentinal microcracks formation with various new instrumentation methods and conventional hand filing method. It also looks into amount of gutta-percha removed after retreatment from the canal and the time required for all the instrumentation technique.

Methodology

Sixty extracted human maxillary first molars with curved roots were mounted on addition silicone impression material incorporated in an aluminium hollow block, then instrumented using step-back preparation with 35 size K files. Obturation was done using gutta-percha with AH plus sealer. These were stored for 14 days and divided into three groups Mani GPR, Endostar Re Endo and H file and were subjected to retreatment procedures. Retreatment was considered complete when no filling material was observed on the canal wall and the canal was smooth and free of visible debris. The samples were examined under scanning electron microscope and the number of cracks were calculated. The percentage of root canal filling material and time taken was recorded.

Statistical Analysis

The data obtained were analyzed by using descriptive statistics, ANOVA (Analysis of Variance), chi-square test and Scheffe's post hoc test through SPSS for window (version 22.0).

Result

All the techniques showed similar amount of crack propagation, with no statistical difference between the group. Retreatment done using H Files required more time and removed less material. The coronal third showed less amount of gutta-percha remnants than the apical third in all groups.

Conclusion

All the groups showed a similar amount of crack propagation. Less number of cracks were observed in the coronal one third and more amount of cracks were found at the apical third. Endostar RE Endo rotary instrument proved to be most effective and least time-consuming. Hedstrom Files required more time and removed less material.