A Novel Index to Analyze Pediatric Rotary File Systems

Introduction

The major goal in pediatric dentistry is to retain primary teeth in the mouth till the physiological exfoliation so as to maintain the integrity of the arch. Pulpectomy, a therapeutic option for pulpally involved primary molars has numerous benefits over extraction. The success of root canal therapy is significantly affected by the complex root canal system in primary teeth, which plays a pivotal role in determining the procedure's outcome. The major goal of root canal instrumentation is to eliminate infection, and the outcome of pulpectomy is significantly influenced by this.¹

When compared to rotary instrumentation, mechanical preparation using traditional hand instruments is time-consuming and may result in iatrogenic problems (canal transportation, apical blocking, ledging, zipping, etc.).²

An efficient chemomechanical preparation is essential for effective canal disinfection and contributes to the success of endodontic procedure. The duration of appointment is closely related to children’s behaviour. Use of rotary instruments for pulpectomy is an emerging practice in pediatric dentistry. Rotary instrumentation in primary teeth was advocated for its ability to provide conical-shaped canals and reduced instrumentation time.³ Elimination of microorganisms from the root canals which can be achieved through removal of vital tissues, residual necrotic material, infected dentine and debris is the most important purpose of endodontic treatment.⁴

It is generally thought that success of root canal treatment is dependent on the elimination of infection and permanent obturation of root canal with a nontoxic material. Most endodontists agree that biomechanical preparation is the most important phase of the treatment. Instrumentation is not only to remove microbes and necrotic debris, but also to modify the canal so that desired root filling can be achieved. Irrigating liquids are used to improve cutting efficacy and to remove debris. The definitive purpose of these chemo-mechanical actions is a spotless, debris-devoid canal that is necessary for ideal canal sealing. The current focus on the usage of cement sealers that adhere to the walls of the canal is an additional reason for the production of a spotless surface. Earlier, the focus was on the ideal filling of root canal, but little is recognized regarding the actual state of the root canal walls post instrumentation and whether it is a surface desirable for sealing.⁵

Therefore in this study, efficiency in debris removal and smooth preparation of the canals were taken into consideration to assess and compare three different pediatric file systems using our indigenously prepared novel index and stereomicroscopic images of prepared samples.

Materials and Methods

The study was conducted in the Department of Pediatric and Preventive Dentistry, Krishnadevara College of Dental Sciences and Hospitals, Bengaluru. This study was carried on 15 extracted deciduous canines with completely formed apices and devoid of root surface caries. The study was conducted in two phases. In Phase I, the selected teeth were divided into three groups of five teeth in each group: Group I - Pedoflex, Group II - Pro AF Baby Gold, Group III - Kedo SG Blue.

Group I

Three Pedoflex files, #20 (yellow), #25 (red), and #30 (blue), were used successively for the preparation of each root canal. The endodontic motor was adjusted at 350 RPM and 1.5 N cm torque.2 RC Help of 1 cm length was used. Irrigation with 2 mL distilled water was done which was repeated twice.

Group II

Rotary file system (Pro AF Baby Gold) was used for the root canal preparation. A total of five files make up this collection: B1 (#20-04%), B2 (#25-04%), B3 (#25- 06%), B4 (#30-04%), and B5 (#40-04%). The canals were shaped using files and an endodontic motor set at 300 RPM and 3 N cm torque.2 RC Help and distilled water were used similar to Group I.

Kedo SG Blue rotary file system was used for the root canal preparation. This rotary file system has three files: D1 (for narrow canals, #25), E1 (for broader canals, #30), and U1 (for anteriors, #40). Canals were prepped with files using an endomotor set at torque of 2.2 N cm and RPM 300.2 RC Help and distilled water were used similar to other groups.

In Phase II, the prepared teeth in each group were sectioned and these sectioned teeth were studied to determine the preparation efficacy of files using stereoscopic images and indigenously prepared novel index.

Our prepared criteria were used to evaluate the debris present in the prepared canals and also the smoothness in each third of tooth to assess the debris removal efficiency of each file system.

Results

For the study, five samples were prepared using Pedoflex file system. These samples were sectioned for evaluation of debris and smoothness. Samples were divided into apical, middle and coronal 1/3rd. Debris and smoothness assessment were done using the novel criteria indigenously prepared by us.

Our indigenous criteria includes two parts - Debris score and Smoothness index

The objective of this novel index was to measure the debris in the canals, to evaluate the debris removal efficiency of the files and smoothness of the canal preparation. This index facilitates the evaluation of efficiency of different rotary files systems (Pediatric).

Debris scoring criteria

- Divide the sectioned tooth into apical third, middle third and coronal third

- Debris present in each third must be identified

- ‘+’ - Debris noted in one small area of particular region (apical, middle or coronal)

- ‘++’ - Debris noted in 2-3 areas

- ‘+++’ - Debris noted in more than three areas

- ‘0’ - Debris absent

Smoothness Index

Divide the sectioned tooth into three parts - apical, coronal and middle third.

Check for the roughness in each third of sectioned tooth (based on presence of dentinal flutes), evaluate whether smoothness is present or absent.

After analysing the stereomicroscopic images of the sectioned teeth samples prepared with Pedoflex, Pro AF Baby Gold and Kedo SG Blue rotary file systems, debris scores were obtained along with smoothness index.

Table 1 shows debris scores of Pedoflex, Pro AF Baby Gold and Kedo SG Blue file systems, and Table 2 shows smoothness index scores of Pedoflex, Pro AF Baby Gold and Kedo SG Blue rotary file systems after the stereomicroscopic image analysis.

Discussion

Mechanical instrumentation is associated with successful pulpectomy treatment. Smooth canal preparation devoid of debris facilitates better obturation and apical seal. Based on our indigenously prepared criteria, debris presence and smoothness of the canals were taken into consideration for analysing the tooth preparation produced by three different file systems.

Considerable research has already been undertaken regarding the efficacy of Pedoflex files. Shimoli Shah et al. concluded that time for instrumentation using Pedoflex files was pointedly less compared to instrumentation using hand K-files.⁶ According to Girish Babu KL et al., Pedoflex files for preparation of primary molars produced superior quality obturation with decreased instrumentation time, obturating time and least postoperative pain.⁷

A randomised controlled trial conducted by Poonacha KS et al. demonstrated superiority of Pro AF Baby Gold files over hand files in relation to time management and efficacy of canal shaping.⁸ Nilesh Rathi et al. in his in vitro study found that Pro AF Baby Gold files result in least amount of apical extrusion of debris. Cleaning efficacy was noted to be better with Pro AF Baby Gold pediatric rotary endodontic files when compared to Kedo-S rotary files.⁹

Sruthi S et al. proved that Kedo SG Blue files (pediatric rotary) presented a noticeable decrease in working time, followed by Kedo SH files (pediatric manual) and Reciprocating manual K files.¹⁰ Priyadarshini P et al. showed a clear reduction in instrumentation time and higher quality of obturation with Kedo-SG Blue rotary file system, followed by Kedo-SH, Kedo-S and Hand K-fles.¹¹

On evaluation of results, first sample in Group I (Pedoflex) showed ‘0’ score for debris index in coronal and middle 1/3rd indicating that debris was not present in any portion of middle & coronal third regions of the preparation; however, a score of ‘+’ was given for apical 1/3rd indicating debris in single area. This connotes that the pedoflex file system produced canal preparation with least debris formation. In the same sample, when smoothness was evaluated, the preparation was found to be smooth from coronal to apical third (based on dentinal flutes presence) indicating the ability of pedoflex file system to attain a smooth canal preparation which is imperative for attaining desired treatment outcome.

On examination of second sample in Group I (pedoflex), a debris score ‘0’ was noted in coronal third, ‘+’ was noted in middle third and ‘++’ was noted in apical third. This indicates that the debris was absent in coronal third, was found in a single zone in middle third and was present in 2-3 areas in apical third, producing a less desirable result compared to first sample. Smoothness evaluation of the same sample exhibited smooth middle and coronal thirds, while roughness (indication of dentinal flutes) was observed in the apical third. Less beneficial outcome was noted in this sample compared to the initial sample prepared with Pedoflex.

Third sample showed score ‘0’ in the middle and coronal thirds which indicates absence of debris in both these regions, but a ‘++’ score was noted in apical third denoting the presence of debris in 2-3 areas of apical third. Smoothness evaluation showed that the sample was smooth from coronal to apical third. This reaffirmed the ability of pedoflex files in producing efficient tooth preparation and desired treatment outcome. This sample showed better results compared to second sample but was inferior to that observed in first sample; however, the results were comparable.

Sample four showed a score of ‘0’ in the coronal third indicating absence of debris and ‘+’ score in apical & middle thirds indicating the presence of debris in one particular region. In terms of smoothness index, the sample demonstrated smooth middle and coronal third preparations but rough apical third preparation indicating dentinal flutes. The result was better than second sample in terms of debris criteria.

Fifth sample showed ‘0’ score for debris in middle and coronal thirds, ‘+’ in apical third indicating presence of debris in a small area in the apical third. Rough middle third preparation was noted with relatively smooth middle and coronal third preparation.

On analysis of samples prepared by Group II (Pro AF Baby Gold), first sample produced a debris score of ‘++’ in apical and coronal thirds denoting the presence of debris in 2-3 areas while ‘+’ was noted in middle third indicating debris presence in a single zone. This debris observed is disadvantageous for a desirable future outcome. When sample was evaluated for smoothness (dentinal flute presence), it was found to be rough in coronal and apical thirds indicating dentinal flutes presence, but middle third was found to be smooth. This result is less appreciated as roughness can hinder the achievement of a better treatment result.

Second sample of Group II (Pro AF Baby Gold) showed a debris score of ‘+’ in the middle and coronal thirds which denotes the appearance of debris in a single area of the respective regions and ‘++’ was noted in the apical third indicating presence of debris in 2-3 areas. Though the debris present was comparatively less than the initial sample, presence of debris is still undesirable. When prepared sample’s smoothness was evaluated, coronal third was found to be smooth while roughness was observed in apical and middle third.

Third sample showed ‘+’ debris score from coronal to apical third indicating the presence of debris throughout the canal. A smooth middle and coronal thirds was noted with rough apical third preparation indicating dentinal flute presence in the apical third. Sample showed least debris compared to first and second samples and smoothness too was comparatively better.

Fourth sample showed ‘+’ score in middle and coronal thirds and ‘++’ in apical third which is similar to second sample and the sample was found to be rough in coronal and apical thirds indicating dentinal flutes presence in these regions while middle third was found to be smooth.

Fifth sample showed ‘+’ score from coronal to apical third similar to the third sample. Coronal third preparation was found to be smooth but middle and apical third preparation was smooth which is similar to sample 2.

When we compared the samples of each group with each other, Pedoflex samples evidently showed better preparation with minimal debris and better smoothness followed by Pro AF Baby Gold and most undesirable preparation was noted with Kedo SG Blue file system.

Conclusion

• On analysing the debris and smoothness index scores using our novel criteria, we arrived at a conclusion that Pedoflex files have the best canal preparation capability with less debris and better smoothness, followed by Pro AF Baby Gold and Kedo SG Blue file systems.

• Preparations with Pedoflex could provide a better treatment result compared to Pro AF Baby Gold and Kedo SG Blue.

Conflict of Interest

None