Comparison of Cleaning Efficacy of Different Rotary Files in Primary Teeth—An In vitro Study

ABSTRACT

Aim:

The aim of the present study was to comparatively assess the cleansing efficiency of dissimilar rotary files in deciduous teeth.

Materials and Methods:

Forty-five deciduous anterior teeth that had been subjected to extraction were chosen for this research. The teeth were included if they had a minimum of 2/3^rd undamaged root portions. Coronal entrée was completed using round diamond burs. All 45 samples were allocated at random to one of the following three groups: Group I: Control group in which the radicular canal was not subjected to any form of instrumentation, Group II: The radicular canal was subjected to instrumentation employing rotary ProTaper files, Group III: The radicular canal was subjected to instrumentation with rotary MTwo files. The samples were subjected to immersion in a succession of diluted ethyl alcohols to permit dehydration: With a change of solution every eight hours, the first 16 hours were spent in 70% alcohol, followed by eight hours in 80% alcohol, eight hours in 95% alcohol, and eight hours in 100% alcohol. The samples thus subjected to dehydration were cleared by immersion in methyl salicylate for six hours. Under a stereomicroscope with a 10x magnification, the root canals were examined by a person who was blinded to the groups in order to look for any traces of ink in the coronal, middle, and apical third of the canals.

Results:

In the control group, greater residual remains were present in the apical 3^rd at 2.16 ± 0.08 followed by the coronal 3^rd at 2.02 ± 0.14, and then in the middle 3^rd at 1.88 ± 0.10. While using the ProTaper files, greater residual remains were present in the middle portion at 1.68 ± 0.16, followed by the coronal third at 0.94 ± 0.09, then the apical third at 0.98 ± 0.22. Greater residual remains were again noted with the MTwo files in the mid-portion at 1.44 ± 0.18, followed by the coronal part at 0.86 ± 0.10 and then the apical part at 0.82 ± 0.04. Differences among these groups were statistically significant with a P value < 0.001.

Conclusion:

The present study concluded that either of the file types used exhibited reasonably lower remnant score values in the apical third versus the middle/coronal thirds. Nonetheless, MTwo type files delineated superior capacity at removing debris versus the ProTaper file types at the apical level.

INTRODUCTION

Pedodontics is one of the key significant specializations of dental practice. The aims that the specialty of pedodontics looks to attain are not adequately put into practice in spite of the knowledge of the current notions followed in pedodontia. Inappropriate management of deciduous teeth causes trouble in mastication, nourishment, as well as the growth of children at an essential phase of life, which may influence social conduct. Conserving deciduous dentition till their physiological shedding is among the highly significant aims of pedodontics, to preserve the natural function, visual parameters, and accurate articulation of alphabets, proper development, as well as conservation of the apt position for the erupting permanent dentition eventually.[1]

The early loss of deciduous dentition leads to modifications in the chronology as well as the succession of erupting permanent dentition. Safeguarding the deciduous dentition up till the physiological shedding adds to adequate chewing, articulation as well as appearance while avoiding harmful habits in the pediatric population. Consequently, deciduous dentition with pulpal inflammation or necrosed pulp is implicated in root canal treatment.[2]

The triumph of pulpectomy is dependent on the removal of irritants via cleansing as well as shaping of the radicular canals. The principal goals of cleansing as well as shaping of the radicular canals are getting rid of the hard plus soft tissue comprising bacterial organisms, rendering a way for irrigant solutions to the apical third, providing space for insertion of medications as well as consequent obturation, and maintaining integral root morphology. The character of root canal size, shape, in addition to curvatures and physical features of the armamentarium, avoids the likelihood of a standardized, tapering, and flowing preparation.[3]

Radicular canal systems have been prepared with an array of equipments as well as methodologies. Nickel–titanium (NiTi) alloys were manufactured early in 1962 while Walia declared in 1988 that radicular file systems composed of the NiTi alloy comprise 55 (w/w) nickel plus 45 percent (w/w) titanium. NiTi files exhibit double/triple elasticity during torsion/bending movements with the benefit of offering greater corrosion resistance versus file systems made up of stainless steel. In the current age, numerous rotary NiTi root canal files have made themselves commercially available. The therapeutic actions achieved by the use of rotary armamentarium are influenced by the correct selection of their design as well as characteristics, thereby stressing the correct preference of the rotary endodontic method.[4]

Apt utilization of the rotary armamentarium alters the radicular canal to a greater conical form, thereby enhancing the class of obturation. The design as well as the elasticity of equipments made up of NiTi alloy permits the files to conserve the unique anatomy of radicular canals with curvatures, particularly in the deciduous teeth, and lessen technical mistakes.[5] Therefore, the aim of the current research was to comparatively assess the cleansing efficiency of dissimilar rotary files in deciduous teeth.

MATERIALS AND METHODS

Forty-five deciduous anterior teeth that had been subjected to extraction were chosen for this research. The teeth were included if they had a minimum of 2/3^rd undamaged root portions. Prior to commencing the study, each tooth sample was cleansed using soap with washing under flowing water. A scaler was employed to get rid of calculus that existed on the radicular surface, following which the sample tooth was subjected to storage in 0.5% sodium hypochlorite for 7 days.

Round diamond bursts were used to complete the coronation entrée. After normal saline irrigation of the radicular canals, a K-file with a well-matched diameter was inserted, and the length of the canal was measured at a millimeter from the apex/root bevel. All 45 samples were allocated at random to one of the following three groups.

Group I: Control group in which the radicular canal was not subjected to any form of instrumentation.

Group II: The radicular canal was subjected to instrumentation employing rotary ProTaper files.

Group III: The radicular canal was subjected to instrumentation with rotary MTwo files.

Evaluation of patent canals as well as determination of their working length was performed by passage of a size 10 K-file. Irrigation was performed with sodium hypochlorite (1%) using a 31-gauge needle subsequent to the utilization of every instrument. All root canals were subjected to irrigation using 5 mL of sodium hypochlorite. Canal recapitulation was executed following the application of every file. Files were frequently subjected to wiping with wet gauze to get rid of tissue debris.

In group I; all fifteen samples were subjected to manual instrumentation using the step-back approach and K-files up to file ISO size 30. In group II, all fifteen samples were subjected to cleansing with the ProTaper files using a crown-down procedure with two equipments in subsequent series: SX was introduced within the canal to approximately 3mm beyond the radicular canal opening plus S2 file was subjected to insertion until the working length. In group III, all 15 samples were subjected to preparation with MTwo files utilizing the crown-down method. The period of instrumentation within every radicular canal was calculated via a chronometer. In each of the three research groups after flushing the canals with 5 ml of regular saline, they were dried with absorbent paper tips. The apical ends were then sealed with sticky wax before the pulp chamber was filled with temporary cement (Coltosol, Coltene/Whaledent AG, Switzerland). The samples thus subjected to instrumentation were stored under wet conditions.

Evaluation of the cleaning efficacy of rotary files

Decalcification of the samples was performed by immersion in 7% hydrochloric acid for 48 hours. Every day the acidic solution was changed. Post-decalcification, the samples were subjected to washing beneath flowing water. The samples were immersed in diluted ethyl alcohols in a series of concentrations to allow for dehydration: first, 70% alcohol for 16 hours (with a change of solution every eight hours), then 80% alcohol for eight hours, 95% alcohol for eight hours, and 100% alcohol for eight hours. The samples that had been dehydrated in this way were cleaned after six hours of immersion in methyl salicylate.

Under a stereomicroscope with a 10x magnification, the root canals were examined by a person who was blinded to the groups in order to look for any traces of ink in the coronal, middle, and apical third of the canals. The following evaluation criteria were used:

Score 0: complete clearing (canal was totally clean)

Score 1: near total ink elimination (traces of ink in a few regions)

Score 2: incomplete ink elimination (leftovers of ink noted on certain walls in various areas)

Score 3: absence of ink elimination (substantial quantity of ink present)

Statistical analysis

The scores thus acquired were subjected to tabulation and statistical analysis with SPSS (version 18). Kruskal–Wallis ANOVA test and Mann–Whitney Utest were utilized to establish the inter- and intra-group disparity, at a significance level of P < 0.05.

RESULTS

Table 1 shows the intra-group contrast evaluation of the cleansing effectiveness of rotary files at coronal, middle, and apical thirds. In the control group, greater residual remains were present in the apical 3^rd at 2.16 ± 0.08 followed by the coronal 3^rd at 2.02 ± 0.14, and then in the middle 3^rd at 1.88 ± 0.10. While using the ProTaper files, greater residual remains were present in the middle portion at 1.68 ± 0.16, followed by the coronal third at 0.94 ± 0.09, then the apical third at 0.98 ± 0.22. Greater residual remains were again noted with the MTwo files in the mid-portion at 1.44 ± 0.18, followed by the coronal part at 0.86 ± 0.10, and then the apical part at 0.82 ± 0.04. The differences within each group were not statistically significant.

Table 1.

Intra-group comparison of cleaning efficacy of rotary files at coronal, middle, and apical levels

Rotary file systems	Mean±SD			K ANOVA	P
	Coronal	Middle	Apical
Group I: Control group	2.02±0.14	1.88±0.10	2.16±0.08	25.38	0.084
Group II: ProTaper files	0.98±0.22	1.68±0.16	0.94±0.09	20.16	0.059
Group III: MTwo files	0.86±0.10	1.44±0.18	0.82±0.04	22.14	0.054

Table 2 exhibits the inter-group contrast evaluation of the cleansing effectiveness of rotary files in the coronal, middle, and apical portions. Upon evaluating among the groups, greater residual remains were seen with the ProTaper files in the middle third at 1.68 ± 0.16 plus the coronal third at 0.98 ± 0.22, as well as greater residual remains were seen in the middle level with the use of MTwo files at 1.44 ± 0.18. The MTwo files system showed the least residual remains at all of the three positions evaluated. Differences among these groups were statistically significant with a P value < 0.001.

Table 2.

Inter-group comparison of cleaning efficacy of rotary files at coronal, middle, and apical levels

Obturation systems	Mean±SD
	Coronal	Middle	Apical
Group I: Control group	2.02±0.14	1.88±0.10	2.16±0.08
Group II: ProTaper files	0.98±0.22	1.68±0.16	0.94±0.09
Group III: MTwo files	0.86±0.10	1.44±0.18	0.82±0.04
K ANOVA	27.12	24.36	23.12
P	0.001	0.001	0.001

DISCUSSION

There is overpowering substantiation that the decrease of microbial organisms within the root canals is the key purpose of root canal treatment. The vital aims that the dental physician must achieve with endodontic therapy are absolute disinfection of the radicular canal legroom, and cessation of a succession of the peri-radicular tissue inflammatory process, therefore creating encouraging circumstances for peri-radicular healing of tissues. These can be attained by employing an apt mechanical radicular canal preparation that is elementary for a victorious root canal therapy.[6]

The complex morphology of radicular canals in deciduous dentition makes radicular canal preparation challenging as well as a laborious task in the pediatric population. Hence, rotary file systems are regarded as opportune as well as suitable to make possible their utilization in endodontic therapy in children. Debridement of the root canal walls is the goal of preparing the canals as well as is thought to be indispensable for endodontic therapy in deciduous dentition. Although the belief following mechanical cleansing plus shaping of radicular canals is equivalent for the deciduous and permanent teeth together, cautious management is necessary for the slender as well as fine root canals of deciduous teeth. Anterior primary teeth with fairly straight canal morphological characteristics were chosen for consistency in the current research.[7]

Barr et al.[8] originally discussed the utility of rotary biomechanical preparation of primary teeth. There is no obvious course of action for the instrumentation of deciduous –tooth-root canals using rotary files. Kuo et al.[9] established that with an amended approach, ProTaper Ni-Ti rotary files can be securely and competently employed for endodontic preparation in deciduous teeth.

Reasonably lower remainder scores were achieved at the apical 3^rd of the prepared radicular canal with the 2 chosen rotary file systems in comparison with coronal and middle 3^rd regions. Studies by Taha et al.[10] Rahimi et al.[11] as well as Júnior et al.[12] showed lower residual remains scores at the apical 3^rd of radicular canals. The likely justification for this might be the oval form of the canal at the coronal, middle 3^rd while attaining a round contour as it advances toward the apex. The dentinal specks detached from the root canal walls are passed in the coronal direction via the flutes of the file, owing to the employment of rotary file systems with a rounded cross section. This elimination is as it appears efficient to a lesser amount when the canal has an oval shape cross sectionally. Canals with an oval shape room hinder the working file coming in contact with all the surfaces of radicular dentin. In such circumstances, the debris that is passed in the coronal direction or being enclosed/filled in the flute space of the file gets crowded dynamically in the region with the smallest amount of opposition. It is plausible to conjecture that dentinal elements were dynamically filled into soft tissue remains in regions that have not been prepared and are frequently defiant to irrigation using a syringe/needle.[13] Analogous to the current research, preceding standard error of the mean investigations documented that the quantity of residue was lower at the apical level versus the coronal and middle.

Additional study is required to verify and discuss in detail canal transport systems, the surface area of regions not subjected to instrumentation, as well as conservation of dentinal thickness which affects the prognostic steadiness of deciduous teeth.

CONCLUSION

The current research arrived at a conclusion that either of the file types used exhibited reasonably lower remnant score values in the apical third versus the middle/coronal thirds. Nonetheless, MTwo type files delineated superior capacity at removing debris versus the ProTaper file types at the apical level.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.