Tanta Dental Journal

: 2018  |  Volume : 15  |  Issue : 1  |  Page : 14--18

Cleaning efficacy of rotary versus manual system for root canal preparation in primary teeth

Momen H Elnagar1, Nagwa A Ghoname2, Walaa M Ghoneim3,  
1 Dentist at the Ministry of Health, Faculty of Oral and Dental Medicine, October 6 University, 6th October City; Department of Pedodontics, Faculty of Dentistry, Tanta University, Tanta, Egypt
2 Department of Pedodontics, Faculty of Dentistry, Tanta University, Tanta, Egypt
3 Department of Endodontics, Faculty of Dentistry, Tanta University, Tanta, Egypt

Correspondence Address:
Momen H Elnagar
Faculty of Oral and Dental Medicine, October 6 University, 6th October City


Introduction Primary teeth are considered natural space maintainers and should be maintained till their exfoliation is chronologically appropriate. The success of endodontic treatment is directly related to the microbial reduction in the root canal system as a result of chemomechanical preparation. Objective This study was carried out to evaluate and compare cleaning efficacy of rotary and manual systems for root canal preparation in primary teeth. Materials and methods Thirty extracted single-rooted human primary teeth were selected. In group I the root canals were instrumented manually with Ni-Ti Flex K-file. Revo-S rotary instruments were used for canal preparation in group II. Irrigation with 1% sodium hypochlorite was done at each file change. Roots were split longitudinally and processed for scanning electron microscope examination. For evaluation of cleaning efficiency two separate scores were used for evaluation of debris and smear layer at three root canal thirds. Results However, both techniques did not achieve complete clean walls, Revo-S rotary system achieved better cleanliness than that obtained by manual instrumentation at all root canal levels. Conclusion Revo-S rotary system might be an alternative method for preparing root canal in primary teeth with better cleaning efficiency.

How to cite this article:
Elnagar MH, Ghoname NA, Ghoneim WM. Cleaning efficacy of rotary versus manual system for root canal preparation in primary teeth.Tanta Dent J 2018;15:14-18

How to cite this URL:
Elnagar MH, Ghoname NA, Ghoneim WM. Cleaning efficacy of rotary versus manual system for root canal preparation in primary teeth. Tanta Dent J [serial online] 2018 [cited 2019 Jan 19 ];15:14-18
Available from: http://www.tmj.eg.net/text.asp?2018/15/1/14/229244

Full Text


Pulpectomy is a root canal procedure for irreversibly infected or necrotic pulp tissue due to caries or trauma. Removal of organic debris and reduction of microorganisms from root canals is the key goal in endodontic treatment and the main purpose of filing in pulpectomy procedure [1],[2].

Hand instrumentation may require greater preparation time and stainless steel files larger than number 15 or 20 become inflexible with increased rigidity and tendency to straighten inside the canal causing complications of canal preparation as canal transportation, strip perforation, or pushing necrotic debris apically [3],[4]. Barr et al. [5] were the first to describe a pulpectomy procedure for primary teeth using Profile 0.04 rotary files. They considered this simplified technique a more effective way to debride the uneven walls of primary teeth root canals with less errors and resulted in a smooth funnel-shaped preparation.

A new generation of nickel–titanium rotary instruments, Revo-S had been developed with asymmetrical cutting profile which facilitates root canal penetration by a snake-like movement, reduces instrument stress and offers a root canal shaping which is adapted to the biological imperatives [6]. The presence of remaining dentinal chips, pulpal fragments and necrotic debris may cause undesired consequences of inflammation, delayed healing or even harms the underlying teeth buds [7], smear layer being a loosely adherent structure, should be removed from the surface of the root canal wall because it may limit the effective disinfection of dentinal tubules by preventing intracanal medicaments from penetrating the dentinal tubules and compromise the seal between the filling materials and the canal wall [8],[9],[10].

Evaluation of fine debris and smear layer require higher magnification levels that are achieved only through the use of scanning electron microscope (SEM) which was proved to be an efficient method to investigate and compare the influence of different endodontic instruments on the morphology and cleanliness of dentin surfaces [11],[12].

 Materials and Methods

Collection of teeth and their storage

Thirty extracted primary anterior teeth collected from Pedodontic Clinic, Faculty of Dentistry, Tanta University. Extracted teeth were retained primary incisors or canines that were planned before for serial extraction and/or avulsed teeth due to trauma. Approval for this research was obtained from Tanta Faculty of Dentistry Research Ethics Committee.

Teeth had no or minimal root resorption at least 8–12 mm of intact root length was present, digital periapical radiographs were taken to detect internal resorption or intracanal calcification. Freshly extracted teeth were washed under running water and any remaining soft tissue fragments were removed from their root surfaces and stored in sterile saline solution.

Method of root canal preparation

Coronal access was prepared in each tooth, then #10 K-file (Dentsply/Maillefer, Ballaigues, Switzerland) was introduced passively to determine the patency of the root canals. Working length was determined to be 1 mm short of apical foramen that was sealed with casting wax before instrumentation to simulate the in-vivo apical counter pressure and prevent seepage of irrigant. The teeth then numbered and randomly divided into two groups of 15 teeth for each group.

Group I (positive control group)

Hand instrumentation was performed using step-back technique with Ni-Ti Flex K-file (Dentsply/Maillefer). The files were used in the following sequence, #20/0.02 up to #35/0.02 master apical file and stepped back to file #50/0.02 and coronal flaring was done with file #55/0.02.

Group II (study group)

Rotary instrumentation was performed using crown-down technique with Revo-S system (Micro-Mega, Besancon, France) at rotation speed of 300 rotations/min and minimum torque of 0.8 Ncm. The files were activated by 20: 1 gear reduction handpiece connected to the endomotor (Endo-Mate DT; NSK, Tokyo, Japan). The following sequence was performed, SC1 (#25/taper 0.06) only to reach coronal two-thirds of the working length then SC2 (#25/0.04), SU (#25/0.06) AS file (#30/0.06) and AS file (#35/0.06) master apical file to the full working length. Each instrument was coated with Glyde File-Prep root canal conditioner before it was introduced into the root canal for lubrication as recommended by the manufacturer. Irrigation was done in both groups with freshly prepared 1% sodium hypochlorite solution in 5 ml quantity during each file change. Root canals of each tested group were dried with paper points.

Scanning electron microscope examination

A small cotton pellet was placed inside access cavity before longitudinal root sectioning to prevent the entrance of dentinal shavings into the root canal and roots were grooved longitudinally on buccal and lingual aspects using a double faced diamond disk mounted on a low speed handpiece followed by cleavage into two halves with a thin metal spatula. The half containing the most visible part of apex was selected and coded. Each specimen was then dried, mounted on metallic stubs and coated with gold sputter. Specimens were examined using SEM at × 500 and × 1500 for evaluation of coronal, middle and apical thirds [13]. Images were analysed independently by two calibrated blinded evaluators using Hulsmann scoring system for debris and smear layer [14].

The debris scale:

Score 1: clean root canal wall and only small debris particles

Score 2: few agglomerations of debris

Score 3: many agglomerations of debris covering less than 50% of the root canal walls

Score 4: debris covers more than 50% of the root canal walls

Score 5: compete or nearly complete root canal wall coverage with debris.

The smear layer scale:

Score 1: no smear layer and all dentinal tubules are open

Score 2: a small amount of smear layer and some dentinal tubules are open

Score 3: homogenous smear layer covering the root canal wall and only a few dentinal tubules open

Score 4: complete root canal wall covered by a homogenous smear layer and no open dentinal tubules

Score 5: heavy, homogenous smear layer covering the complete root canal wall.

Statistical analysis

Data were analysed using Mann–Whitney pair-wise test to reveal statistically significant differences among tested groups at each root level. Kruskal–Wallis test was also done to compare between different root canal levels in each group. Whenever statistically significant difference was recorded, Mann–Whitney pair-wise comparison test was performed at significance level of P value 0.05 or less using SPSS program version 17.0 (SPSS Inc., Chicago, Illinois, USA).


However, no group demonstrated completely clean canals, Revo-S rotary file provided overall cleaner canal walls than Ni-Ti Flex K-file in all root canal levels specially at the apical root level and the difference between both groups was highly significant for both debris with and smear layer as shown in [Table 1] and [Table 2]. The difference in cleanliness among three root canal levels in each group was nonsignificant in rotary group with P values of 0.93 and 0.16 for debris and smear layer, respectively. While in manual group, the difference was significant with P values of 0.001 for debris and 0.004 for smear layer.{Table 1}{Table 2}


Chemomechanical preparation is an integral part of root canal treatment; it includes mechanical cleansing with instruments and irrigants to remove infected tissues and residual necrotic material, providing the ideal conditions for healing and integrity of radicular structure [15],[16]. Cleaning efficiency depends on many factors including the type of the instrument, instrumentation technique and the irrigation solution in addition to the inherent anatomy of the root canal system [17],[18].

This study aimed to evaluate and compare cleaning efficacy of Revo-S rotary system and Ni-Ti Flex K-file in primary teeth, since rotary instrumentation technique allows more rounded and conservative preparation and had proven to be efficient in reducing required time which favours patient cooperation rather than conventional manual technique [19],[20]. Revo-S system was used in a crown down technique up to master apical finishing file AS #35, manual instrumentation with Ni-Ti Flex K-file was used in a step-back up to master apical file #35 to obtain nearly similar apical preparation diameter. Sodium hypochlorite is the best available canal irrigant owing to its antibacterial and organic tissue dissolving properties, so, it was used in this study for both groups to solely compare the cleaning efficiency of the used instruments under the same irrigation regimen [21],[22].

Cleaning efficiency was evaluated in the coronal, middle and apical portions of the root canals by means of SEM to achieve higher magnification. Results revealed that none of rotary or manual instrumentation produced completely clean canal walls for debris and smear layer; however, Revo-S system showed significantly cleaner walls than those prepared with Ni-Ti Flex K-files as shown in [Figure 1] at coronal third, [Figure 2] at middle third and [Figure 3] at apical third and better smear layer removal as shown in [Figure 4] at the coronal level. These results coincide with results reported by Soares et al. [13], Katge et al. [23], Musale and Mujawar [24] who found significantly overall better cleanliness with different rotary systems compared with manual technique.{Figure 1}{Figure 2}{Figure 3}{Figure 4}

The previous results disagreed with Silva et al. [25], Bahrololoomi et al. [26], Moghaddam et al. [27], Pinheiro et al. [19]who found no significant difference in cleaning efficiency between manual and other rotary systems. This difference may be attributed to the degree of root canal curvature, number of files, instrumentation techniques, irrigation protocols and methods used for cleaning evaluation.

Present study showed that debris and smear layer was better in coronal and middle root canal levels than apical level in both groups and the difference between root canal levels in each group was significant after manual instrumentation and nonsignificant after rotary instrumentation. These findings may be attributed to the difference in the file design itself and less accessibility of the apical portion for instrumentation and sufficient irrigation.

However, score 3 for smear layer was the most common score in both groups at middle and apical root level as shown in [Figure 5] and [Figure 6], respectively, score 1 for debris and smear layer was found in the apical root canal level after rotary instrumentation as shown in [Figure 7], this finding in agreement with Soares et al. [13], who found also score 1 in apical root canal level despite the difference in the rotary file system and type of root canal lubricant paste that have been used. This observation may be attributed to the unique design of the Revo-S rotary files with asymmetrical cutting profile and crown-down technique used for root canals preparation that allows the upward removal of dentinal debris and avoids their packing inside the canal [6]. The limitation in the present study were, firstly the study was carried out as in-vitro study, and the second one was the use of root canal lubricant with Revo-S system as recommended for most of Ni-Ti rotary instruments.{Figure 5}{Figure 6}{Figure 7}


According to the findings obtained in the current study, it can be concluded that Revo-S rotary system might be an alternative method for preparing root canal in primary teeth with better cleaning efficiency.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.


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