Indian Journal of Dental Sciences

ORIGINAL ARTICLE
Year
: 2017  |  Volume : 9  |  Issue : 1  |  Page : 26--29

An in vitro study: Evaluation of intracanal calcium hydroxide removal with different file systems


Atul Jain, Nakul Patidar, Neeraj Nigam, Kanchan Bhadoria, Bharat Choudhary 
 Department of Conservative Dentistry and Endodontics, RKDF Dental College and Research Centre, Bhopal, Madhya Pradesh, India

Correspondence Address:
Nakul Patidar
Department of Conservative and Endodontics, RKDF Dental College and Research Centre, N.H. -12, Hoshangabad Road, Misrod, Bhopal - 462 026, Madhya Pradesh
India

Abstract

Background: Calcium hydroxide (Ca(OH)2) is the most commonly used intracanal material; it needs to be removed in entirety before obturation. Several techniques have been used for the same including use of various hand and rotary files. Aim: This study was carried out to compare the efficacy of Hand K files and single and multiple rotary file system in removal of Ca(OH)2. Methodology: Distobuccal root of 45 maxillary molars were selected on the basis of specified inclusion and exclusion criteria. They were divided into three groups - Group 1 (H and K file), Group 2 (HERO Shaper), and Group 3 (One Shape). Biomechanical preparation (BMP) was carried out as per the manufacturer's instructions; 2.5% sodium hypochlorite was used as the irrigant and 17% ethylenediaminetetraacetic acid as the penultimate irrigant. Ca(OH)2powder was mixed with normal saline to obtain a paste; canals were filled with this paste using a Lentulo spiral and were sealed. After 7 days, Ca(OH)2was removed, using the same file system as that used for BMP. Samples were sectioned longitudinally and evaluated under a stereomicroscope. Statistical Analysis: Statistical analysis of the obtained data was carried out using one-way analysis of variance test. Results: HERO Shaper displayed better removal of Ca(OH)2than One Shape and Hand K file. Moreover, removal was better in the middle third of canal than apical third. Conclusion: Multiple rotary file system (HERO Shaper) is more effective in removal of Ca(OH)2than the single file system (One Shape)



How to cite this article:
Jain A, Patidar N, Nigam N, Bhadoria K, Choudhary B. An in vitro study: Evaluation of intracanal calcium hydroxide removal with different file systems.Indian J Dent Sci 2017;9:26-29


How to cite this URL:
Jain A, Patidar N, Nigam N, Bhadoria K, Choudhary B. An in vitro study: Evaluation of intracanal calcium hydroxide removal with different file systems. Indian J Dent Sci [serial online] 2017 [cited 2022 Jul 2 ];9:26-29
Available from: http://www.ijds.in/text.asp?2017/9/1/26/201633


Full Text

 Introduction



Bacteria and their by-products or necrotic pulp can cause pathologic changes, in the periapical tissues. Hence, the first objective of endodontic treatment is the elimination of bacterial infection and debris from the root canal.[1] There are various methods which help in reducing the root canal infection such as mechanical instrumentation along with irrigant solutions and use of medicaments.[2] Intracanal dressing has been advocated to disinfect the root canal system enhancing the success of root canal treatment.[3]

Calcium hydroxide (Ca(OH)2) was first introduced in endodontics by Herman in 1920. At present, Ca(OH)2 is one of the most commonly used intracanal medicament. It is alkaline in nature with a pH of approximately 12.5. It has antimicrobial activity,[2],[3],[4],[5],[6] has tissue-dissolving ability,[4],[5] and inhibits tooth resorption.[5] It even leads to hard-tissue formation.[6] Because of these abilities, Ca(OH)2 has been recommended for use in several clinical situations, its most common indication is as an antimicrobial agent in endodontic therapy.[7]

Before obturation, entire intracanal dressing has to be removed;[8] otherwise, residue of Ca(OH)2 present on root canal wall produces a negative impact on the prognosis of treated tooth. Residue of Ca(OH)2 affects the sealer penetration into the dentinal tubules, physical properties, adhesion of sealer, and dentinal bond strength.[9]

Several techniques have been proposed to remove the Ca(OH)2 dressing from the root canal system, including use of endodontic Hand file, sonic activation, passive ultrasonic irrigation, canal brush system, and nickel-titanium (NiTi) rotary instruments.[9] Removal with Hand files using irrigation solutions may be insufficient, so the use of NiTi rotary instruments has been advocated.[9] Among the latter, a wide variety of multiple rotary file systems such as Profile, HERO Shaper, and ProTaper have been employed.

Among rotary files, single file systems are gradually gaining ground, at the expense of multiple file system; however, the literature regarding the use of former for the removal of intracanal medicaments is far and few. Hence, this study was carried out to compare the effectiveness of One Shape (single file system) with HERO Shaper (multiple file system) and Hand file system for removal of Ca(OH)2 from the root canal.

 Methodology



Freshly extracted permanent maxillary molar teeth were collected from the Outpatient Department of Oral Surgery at RKDF Dental College and Research Centre, Bhopal, Madhya Pradesh, India. Following extraction, teeth were washed thoroughly under running water and cleaned with ultrasonic instruments. They were then disinfected with 5.25% sodium hypochlorite. Radiovisiography of each tooth was taken individually.

Out of these, 45 teeth, free of root fractures, root canal treatment, resorption, severe root curvature or calcification, caries, or other defects were selected for this study.

The distobuccal root was sectioned at cementoenamel junction (measuring 12 mm in length) using a diamond disc and water spray. A #10 K file (MANI, Japan) was inserted into the canal till apex of the root and working length was established 1 mm short of the apex. Teeth were divided into three groups and treated as given below [Table 1].{Table 1}

Group 1: Teeth were prepared manually using step-back technique and the apical preparation was carried out till No. 25 with 2% taper K files Group 2: Teeth were prepared with rotary HERO Shapers file system, using crown-down technique till No. 25 with 4% taper files Group 3: Teeth were prepared with One Shape rotary file of size 25 and 6% taper.

During biomechanical preparation (BMP), 2.5% sodium hypochlorite was used as irrigant. Penultimate rinse was carried out with 17% ethylenediaminetetraacetic acid for 1 min and distilled water was used as final rinse. Root canal was dried with paper point.

Ca(OH)2 powder containing barium sulfate (Prevest Denpro, India) was mixed with normal saline to obtain a paste. The paste was filled into the canal with the help of No. 20 Lentulo spiral, and temporary filling of calcinol, 3–4 mm in thickness was placed over a moist cotton pellet. The samples were incubated at 37°C and 100% humidity for 7 days. After 7 days, temporary filling was removed with the help of spoon excavator, and Ca(OH)2 was removed in each group using the same file system, which used for BMP.

Two longitudinal grooves were made in the buccal and lingual aspect of each root, with a diamond disk and split into two halves by a chisel. Each section was examined under a stereomicroscope (Lafco, India) at ×20 magnification, and photograph was taken with the help of a digital camera (Nikon, Japan).

Photographs were evaluated by a person, unassociated with the study [Table 2] and [Table 3]. The marked middle and apical portion was evaluated as per the following scores:{Table 2}{Table 3}

Score (1) = Absence of remnants Score (2) = Scattered remnants Score (3) = Mass remnants Score (4) = Densely packed remnants.

Statistical analysis

The collected data were subjected to statistical analysis using one-way analysis of variance test using Statistical Package for the Social Sciences version 19.0 (IBM SPSS Statistics, Bhopal, Madhya Pradesh, India) [Table 4].{Table 4}

 Results



Minimal amount of Ca(OH)2 was found in Group 2 (average score of 0%) and maximal amount of Ca(OH)2 was found in Group 1 (average score of 80%). This difference between the groups was statically significant [Table 2].

Group 3 displayed greater amount of residual content as compared to Group 2 but lesser than Group 1. This difference among the groups was also statically significant.

In the apical third, least amount of Ca(OH)2 residual content was seen in Group 2 (average score of 0%), while maximal amount was seen in Group 1 (average score of 80%) [Table 2].

In the middle third, minimal amount of Ca(OH)2 residual content was seen in Group 2 (average score of 0%), whereas maximal amount was seen in Group 2 (average score of 80%) [Table 3].

 Discussion



Ca(OH)2 is the most commonly used intracanal medicament as it is effective against a wide variety of microorganisms. Before obturation of the canal, removal of entire Ca(OH)2 content is important [2] since it may interact with the sealer and form unstable matrix. Zinc oxide-eugenol-based sealers are the most commonly used because of their satisfactory physicochemical properties.[10] Kuga et al. reported that residual Ca(OH)2 may interact with zinc oxide-eugenol sealer and result in calcium eugenolate formation.[9] These residues might also affect the adhesion of sealer to root canal wall.[9] Sealing ability of silicon-based sealer is also affected by the residual Ca(OH)2.[2] Penetration of sealer in the dentinal tubule improves the sealing ability and retention of obturating material,[11] but this residue acts as a barrier in penetration of the sealer.[2] According to Komabayashi et al., the average size of Ca(OH)2 particles ranges between 0.5 and 2 μm,[12] which is less than the dentinal tubule diameter. As a result, residual Ca(OH)2 particles can easily penetrate and block the dentinal tubules.[12]

In the present study, powder form of Ca(OH)2 was mixed with distilled water because fluid is needed for disassociation of hydroxyl ion. Sterile water or saline is commonly used as carrier in clinical situations. Oil-based preparation of Ca(OH)2 is more difficult to remove than Ca(OH)2 powder mixed with saline.[6] The latter tends to release higher amount of hydroxyl ions within a short span of time whereas former although effective for a longer duration tends to release lower concentration of hydroxyl ions,[6] leading to diminished clinical effectiveness.

In our study, HERO Shaper was found to be most effective in removal of Ca(OH)2 whereas K file was least effective. Fariniuk et al. also found HERO Shaper system to possess better ability for removal of filling material as compared to Manual Hand file.[13] Musale and Mujawar also found rotary files to possess better ability to clean canal and reduce instrumentation time.[14] Koçak et al. so concluded that rotary files are more effective in removal of medicament than Hand file.[15] Böttcher et al. also concluded that Hand files are not able to completely remove Ca(OH)2.[16]

The HERO Shaper has triple helix cross-section,[17],[18] constant taper,[19] positive rake angle,[17],[19],[20] noncutting tip,[17] no radial land,[20] variable flute helical angle [20] or increasing helical angle from tip to shank,[21] variable flute pitch,[17],[20] and work at a speed of 300–600 rpm. Positive rake angle cuts dentine effectively.[22],[23],[24] The long pitch prevents the screwing in phenomenon, increases the cutting action, and facilitates the excision and evacuation of dentine chips. This could be a possible reason for better removal of Ca(OH)2 from root canal.[25] However, studies have reported that flute design and cross-section of files are important factors in efficacy of debris and material removal.[1]

One Shape, single file system, which is the evolutionary child of HERO Shapers, is used in continuous rotation.[26],[27] It possess different cross-sections along the active length of the file, which offers an optimal and improved cutting action in the three zones of root canal (a) apical zone represents three cutting edges, (b) middle zone (transition zone) has cross-section that progressively changes from 3 to 2 cutting edges, (c) coronal zone has two cutting edges.[26],[28] One Shape has an asymmetric cross-sectional geometry that generates traveling waves of motion along the active part of the file.[29] The pitch of One Shape is variable which reduces instrument screwing effects.[24]

Removal of Ca(OH)2 was found to be less with One Shape as compared to HERO Shaper. This could be because HERO Shaper has triple helix cross section with a positive cutting angle with no radial land. It has variable pitch and favorable helical angle of the cutting portion which can remove Ca(OH)2 debris more effectively.[26],[28] Bansal et al. found that dentin is removed less with single file system as compared to multiple file system, which was same as the present study.[30] Dingra et al. attributed better canal shaping ability of One Shape to improved core alloy and variable pitch design.[27] Contrary to the result of our study, Altunsoy et al. in a study found that multiple rotary file system removed similar amount of Ca(OH)2 as single file system.[31]

Arvaniti and Khabbaz concluded that taper of the file does not affect the canal cleanliness.[32] Contrary to this finding in the present study, less tapered instruments were found to be more effective in removal of Ca(OH)2.[32]

In the present study, Ca(OH)2 was removed more effectively in the middle third of the root as compared to the apical probably because of more anatomical variations and constrictions being present in the apical third.[33] Contrary to our finding, Fariniuk et al. in a study found that apical third exhibited smaller amount of remaining filling material as compared to middle and coronal third.[13]

 Conclusion



Multiple rotary file system is more effective in removal of Ca(OH)2 than the single file system, whereas manual file system does not remove Ca(OH)2 from the canal adequately. For more conclusive results, a wider study needs to be undertaken.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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