Comparison of the Efficacy of K-File, Canal Brush Technique, and Sonic Irrigation Technique in the Retrievability of Calcium Hydroxide and Metapex Intracanal Medicaments from Root Canals: An In vitro Cone-Beam Computed Tomography Analysis.

BACKGROUND AND OBJECTIVES: At present, none of the routinely used irrigating agents and activation techniques were able to completely remove the Ca(OH)2 intracanal medicament placed inside the root canal system during endodontic therapy. With this as the background, the aim of this study was to achieve complete removal of Ca(OH)2 when mixed with two different vehicles, using various irrigant activation techniques such as K-file, canal brush technique, and sonic irrigation technique, from the root canals of extracted human teeth.
MATERIALS AND METHODS: Seventy-two mandibular premolar teeth with straight single root canal were selected and filled either with oil-based Metapex or calcium hydroxide powder mixed with distilled water and were activated using different activation techniques such as K-file, canal brush, and sonic MM1500 and NaOCl alone. Volumetric analysis was performed utilizing cone-beam computed tomography.
RESULTS: None of the irrigants used were able to completely remove Ca(OH)2 from root canal. Sonic MM1500 showed significant removal efficacy than K-file, canal brush technique, and NaOCl for both aqueous-based and oil-based calcium hydroxide.
CONCLUSION: Sonic MM1500 performed better than K-file, canal brush technique, and NaOCl in removing both Metapex and Ca(OH)2 powder. Regardless of the vehicles and agitation technique used, the remnants of Ca(OH)2 were present on all thirds of the canal walls. Copyright:

INTRODUCTION

Among the various intervisit root canal dressings, Ca(OH)2 appears to be the most efficient intracanal disinfectant which supports the microbial elimination from the root canal system.[123] However, before the obturation, the Ca(OH)2 medicament has to be completely removed since remnants hinder the penetration of sealers, interfere with bonding of resin sealer, and also interact with zinc oxide eugenol (ZnOE) sealers making them brittle and granular.[3] Hence, complete removal of Ca(OH)2 is mandatory before the obturation.

The canal brush is a highly flexible endodontic microbrush which can be used either manually or with a rotary action for root canal disinfection.[4] The MM1500 Sonic Air is an air-driven handpiece which transmits sonic waves along the endodontic instruments. It can be used either with Rispi Sonic or Shaper Sonic instruments to produce a cavitating action.

In the present study, cone-beam computed tomography (CBCT) was used for the analysis of volume of Ca(OH)2 remaining inside the root canal.

The aim of this in vitro study was to assess the efficacy of three irrigation techniques, K-file, canal brush technique, and sonic irrigation technique for the removal of Ca(OH)2 medicaments mixed with two different vehicles.

MATERIALS AND METHODS

Seventy-two permanent mandibular premolars were selected [Figure 1]. The crowns of the teeth were removed 14 mm from the apex to standardize their length [Figure 2]. Chemomechanical preparation of the root canals was done using ProTaper files to a # F3 instrument [Figure 3] as the master apical file in a crown-down manner.

Figure 1

Sample size

Figure 2

Removal of crown

Figure 3

Chemomechanical preparation

Calcium hydroxide formulations used in this study include calcium hydroxide powder (Merck India Ltd., Mumbai, Maharashtra, India) and Metapex paste (META Biomed Co. Ltd., Korea). Barium sulfate (Nice Chemicals [P] Limited, Kerala) was added to the Ca(OH)2 powder to improve the radio-opacity. The chemically pure (95%) Ca(OH)2 powder was mixed with distilled water in 1:1 ratio. Instruments used to activate the irrigants inside the canal were as follows: K-file, canal brush (Roeko Canal Brush, Coltene/Whaledent, Langenau, Germany), and Shaper Sonic files (Medidenta, NV, USA) attached to Sonic MM 1500 handpiece. The 72 teeth were randomly divided into two groups of 36 teeth each. In Group 1 teeth, Metapex was injected into the canal until the material extruded through the apex. In Group 2 teeth, Ca(OH)2 powder was mixed with distilled water to a thick creamy consistency and was placed into the canals with lentulospiral until the material extruded through the apex. Experimental groups were again subdivided into four subgroups based on the activation technique used for the removal of Ca(OH)2 where each subgroup contains nine samples. The access cavities were temporarily sealed with a cotton pellet and IRM and were stored at 37°C and 100% relative humidity in an incubator for 7 days.

Preretrieval CBCT imaging was done using a NewTom CBCT machine [Figure 4], and the volume of Ca(OH)2 was estimated. The teeth were further divided into four subgroups on the basis of the activation technique used. Irrigants were activated in each subgroup with K-file, canal brush, Sonic MM 1500, and NaOCl accordingly [Figure 5a–c].

Figure 4

Preretrieval cone-beam computed tomography

Figure 5

(a) Activation with K-file, (b) activation with canal brush, and (c) activation with Sonic MM 1500

Experimental protocol

The teeth in each subgroup underwent an irrigation process with the respective irrigant activation technique:

Group 1A (n = 9): Metapex retrieved by hand instrumentation with # 30 K-file after irrigating with 1 ml of 5.25% NaOCl with circumferential motion. The final rinse with 1 ml of distilled water was done

Group 1B (n = 9): Metapex retrieved by placing a small-sized canal brush in a slow-speed handpiece running at 600 rpm and advanced to the working length after irrigating with 1 ml of 5.25% NaOCl. A circumferential motion was made with canal brush for 1 min, and the final rinse was done with 1 ml of distilled water

Group 1C (n = 9): Metapex retrieved using sonic activation with Sonic MM1500 attached with Shaper Sonic file for 1 min after irrigating with 1 ml of 5.25% NaOCl. The final rinse was done with 1 ml of distilled water

Group 1N (n = 9): Metapex retrieved with 1 ml of 5.25% NaOCl without activating the irrigant. The final rinse was done with 1 ml of distilled water

Group 2A (n = 9): Ca(OH)2 retrieved by hand instrumentation with # 30 K-file after irrigating with 1 ml of 5.25% NaOCl with circumferential motion. The final rinse with 1 ml of distilled water was done

Group 2B (n = 9): Ca(OH)2 retrieved by placing a small-sized canal brush in a slow speed handpiece running at 600 rpm and advanced to the working length after irrigating with 1 ml of 5.25% NaOCl. A circumferential motion was made with canal brush for 1 min, and the final rinse was done with 1 ml of distilled water

Group 2C (n = 9): Ca(OH)2 retrieved using sonic activation with Sonic MM1500 attached with Shaper Sonic file for 1 min after irrigating with 1 ml of 5.25% NaOCl. The final rinse was done with 1 ml of distilled water

Group 2N (n = 9): Ca(OH)2 retrieved with 1 ml of 5.25% NaOCl without activating the irrigant. The final rinse was done with 1 ml of distilled water.

A postretrieval CBCT was done, and the volume of remaining material was estimated [Figure 6]. The calculation of Ca(OH)2 volume in each specimen was performed using OnDemand3D software (Cybermed Inc., Korea) [Figure 7].

Figure 6

Postretrieval cone-beam computed tomography

Figure 7

OnDemand3D software analysis of calcium hydroxide volume

The removal efficacy was calculated as ([a − b] 100/a), where “a” was the volume of Ca(OH)2 material packed in the root canal and “b” was the volume remaining after retrieval using four different irrigants. The outcome variable was measured in percentage. The data were statistically analyzed, and the difference between the groups was analyzed by Student's t-test. Within the group, between the test groups, data were analyzed using t-test and F-test followed by postanalysis of variance-Waller–Duncan test.

RESULTS

In specimens filled with Metapex, the maximum removal efficacy at cervical third and apical third was shown by Sonic MM1500 followed by K-file, canal brush, and NaOCl which showed equal efficiency between them. At the middle third, no significant difference was found among any of the irrigating agents used. In specimens filled with calcium hydroxide powder, at the cervical third and middle third, the maximum removal efficacy was shown by Sonic MM1500 followed by K-file, canal brush, and NaOCl which showed equal efficiency between them. At the apical third also, the maximum removal efficacy was shown by Sonic MM1500 for the activation of irrigant followed by canal brush and NaOCl which showed better efficiency than K-file. Overall comparison of Group 1 with Group 2 shows that Sonic MM 1500 is more and highly effective than the rest of the entire treated one [Figures 8 and 9].

Figure 8

Graph showing Metapex removal efficacy of four irrigant activation techniques in Group I

Figure 9

Graph showing calcium hydroxide removal efficacy of four irrigant activation techniques in Group 2

DISCUSSION

An intracanal medicament acts as a physicochemical barrier which prevents the reinfection by cutting off the nutrient supply to the remaining bacteria.[56] Ca(OH)2 was chosen for the study as it is a highly recommended intracanal medicament which demonstrates a well-documented antibacterial activity. Calcium hydroxide has to be removed completely from the root canal before obturation. Margelos et al.[7] reported that the residual Ca(OH)2 potentially interacts with setting reaction of ZnOE-based sealers.

The current endodontic techniques fall short of the goal to remove Ca(OH)2 medicament completely from the root canal system. To overcome this crisis, different irrigant activation techniques have been proposed to improve the efficacy of irrigating solutions.[8]

Endodontic brushes were introduced as an adjunct for the debridement of the canal walls or agitation of irrigants within the root canal.[9] It can also be a useful adjunct to improve the removal of Ca(OH)2 intracanal medicament as the bristles touching the canal walls might mechanically dislodge the medicament. Its role as Ca(OH)2 removing agent has been investigated by Markovic et al.[9] and has been reported that it is an effective removal agent.

Passive ultrasonic irrigation gives better canal debridement efficacy when compared to the use of conventional needle irrigation alone, but it can cause the deformation of canal morphology by uncontrolled dentin removal.[10] Sonic irrigation is different from ultrasonic irrigation as it operates at a lower frequency (1–6 kHz).

In the present study, CBCT was used for the calculation of remaining Ca(OH)2. This technique enables volumetric analysis instead of area analysis with no sectioning of tooth which makes it more accurate.

The results of the present study demonstrated that none of the irrigant activation techniques tested were able to remove Ca(OH)2 completely from the root canal irrespective of the type of vehicles used for mixing. This is in accordance with Wiseman et al.,[11] Mukherjee et al.,[12] Kumar et al.,[13] and Alturaiki et al.[14] However, Sonic MM1500 performed better than K-file, canal brush, and NaOCl in the removal of oil-based as well as the aqueous-based Ca(OH)2. In case of the middle third region, there was no significant difference between any of the activation techniques in the removal of oil-based Ca(OH)2. Followed by Sonic MM 1500, canal brush as well as K-file shows almost equal efficiency in the removal of oil-based calcium hydroxide in the cervical and apical regions. This is in accordance with the findings of Garip et al.[15] In case of aqueous-based calcium hydroxide removal, canal brush, K-file, and NaOCl show almost equal efficiency in the cervical and middle third regions, but in the apical region, canal brush shows better efficiency than K-file and NaOCl. When comparing both the groups, Sonic MM 1500 removed aqueous-based calcium hydroxide better than the oil based. Regardless of the vehicle and the agitation techniques used in the present study, Ca(OH)2 residues were found in all root thirds. The better efficiency of eliminating calcium hydroxide from the root canal by Sonic MM1500 may be because of its primary function of producing vigorous intracanal fluid agitation through acoustic streaming and cavitations.[11]

CONCLUSION

Within the limits of the current study, it can be concluded that none of the irrigant activation techniques using K-file, canal brush, Sonic MM 1500, and 5.25% NaOCl were able to completely remove the Ca(OH)2 from the root canal. Irrigant activation using Sonic MM 1500 performed better than K-file, canal brush, and 5.25% NaOCl in the removal of aqueous-based and oil-based Ca(OH)2, and this is statistically significant. Sonic agitation of the irrigant caused a cleaner canal for both aqueous-based and oil-based Ca(OH)2. There was no significant difference in the efficiency of canal brush and K-file in the removal of oil-based calcium hydroxide, but the canal brush performed better in the removal of aqueous-based calcium hydroxide in the apical region. Regardless of the vehicle and the agitation techniques used in the present study, calcium hydroxide residues were found in all root thirds.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.