Removal of Calcium Hydroxide from Root Canal

TITLE: COMPARATIVE EVALUATION OF EFFICACY OF 10% SODIUM BICARBONATE AND 7% MALEIC ACID IN REMOVAL OF CALCIUM HYDROXIDE PREPARATION FROM ROOT CANAL: A SPIRAL COMPUTERIZED TOMOGRAPHY VOLUMETRIC ANALYSIS (IN VITRO STUDY)

ABSTRACT

Introduction: One of the major goals of endodontic treatment is to eliminate all bacteria from the root canal. Mechanical instrumentation and irrigation with antibacterial solutions are considered essential for root canal disinfection during endodontic treatment. The present study was aimed to assess the efficiency of 10% sodium bicarbonate and compare it with 7% maleic acid in removal of the commercially available paste in silicone oil named as metapex using manual method and combination of both manual and ultrasonic agitation

Method: An In-vitro experimental comparative study was designed. Thirty six single rooted teeth were selected. The teeth were divided into 4 groups; Group A: 7% Maleic acid manual; Group B: 10% Sodium bicarbonate manual; Group C: 7% Maleic acid manual with ultrasoinic agitation; Group D: 10% sodium bicarbonate manual with ultrasonic agitation. Spiral CT was taken after mounting the teeth in a plastic stand using modeling wax. Siemens Emotion duo model of spiral CT with the aid of Syngo software was used for estimating the volume of the remaining material in each tooth.

Results: Volumetric analysis showed 7% Maleic acid (with ultrasonic agitation) to be better than (Manual) wheras 10% Sodium Bicarbonate is proven to be better both (manual) and (with ultrasonic agitation) when compared to 7% Maleic acid (Manual) and (Ultrasonic Agitation).

Conclusion: According to this study overall performance of 10% sodium bicarbonate is proven to be better than 7% Maleic acid in removal of silicon oil based preparation from root canal.

Key words: Calcium hydroxide, Maleic acid, Sodium bicarbonate, Volumetric analysis

INTRODUCTION

Bacteria play an essential role in initiation of pulp and periapical diseases.¹ One of the major goals of endodontic treatment is to eliminate all bacteria from the root canal. Mechanical instrumentation and irrigation with antibacterial solutions are considered essential for root canal disinfection during endodontic treatment. ² However, it has been reported that bacteria might survive inside the root canal and in the dentinal tubules, even after chemo mechanical preparation.³ Intracanal medicaments help to eliminate surviving bacteria in between appointments. The most commonly used and recommended material for intra‑canal endodontic dressing in between appointments is Calcium Hydroxide (Hermann in 1920). It is a strong alkaline substance, with pH of approximately 12.5.⁴ The various vehicles types used in medicament are:⁵

• Water‑soluble. e.g. water, saline and local anesthetic agent
• Viscous vehicles e.g. glycerin, propylene glycol and polyethylene glycol

• Oil‑based vehicles e.g. metacresylate, olive oil, silicone oil, camphor, eugenol, etc.

The medicament vehicle plays important role in the overall disinfection process as it determines the velocity of clearance of medicament, resorbing rate at periapical tissues and within the root canal. Calcium Hydroxide (CH) is usually placed as an intracanal medicament for periods of 1–4 weeks.⁶ Residual CH prevents penetration of sealer into dentinal tubules (Calt and Serper).⁷ CH interacts with zinc oxide eugenol (ZOE) based sealers, preventing the setting of ZOE sealer and making them brittle in consistency and granular in nature (Margelos et al).⁸ Residual CH may increase leakage after obturation when ZOE sealer is used.⁹ Residual CH on the root canal walls affects dentine bond strength and lowers the bond strength of resin based sealer to root dentine.^10,11 Thus, complete removal of CH from the root canal system before obturation is recommended.

Ricucci and Langeland reported a case of a failed root canal treatment because of incomplete removal of calcium hydroxide from the root canal that was placed as intracanal medicament .¹² Lambrianidis et al. have studied the removal efficiency of calcium hydroxide dressing in different vehicles from the root canal using normal saline, 3% NaOCl, 3% NaOCl 17% EDTA as irrigants in combination with hand filing. They concluded that 45% surface area remained covered with calcium hydroxide. It was inferred that not the amount of calcium hydroxide powder in the paste but the vehicle used for making the paste can affect the removal.¹³

Till date there are no study carried out using this material for removal of metapex from root canal, The aim of this in vitro study was to assess the efficiency of 10% sodium bicarbonate and compare it with 7% maleic acid in removal of the commercially available paste in silicone oil named as metapex using manual method and combination of both manual and ultrasonic agitation and spiral computed tomography (CT) was used to analyze the volume of calcium hydroxide removed.

MATERIALS AND METHOD

An in-vitro experimental comparative study was designed. Ethical clearance was obtained from the institutional ethical committee. Thirty six single rooted teeth without fractures, cracks, or any other defects were selected and were stored in normal saline solution that was changed daily till the required number of teeth were collected. Access cavity was prepared and the working length was established 1 mm short of apical foramen. The root canal of each tooth was then instrumented with protaper rotary files (Dentsply Maillefer, Ballaigues, Switzerland) to size F3 (9% taper) using X-smart rotary system and 17% EDTA was used as a lubricant. After each instrument change, the canal was passively irrigated with normal saline followed by 2.5 ml of 3% NaOCl solution using 2.5 ml disposable plastic syringe and 27 gauge needle keeping the needle 2 mm short of the apex. After root canal preparation a size 20 K file was passed beyond the apex to remove any dentinal plug remaining into the canal. The calcium hydroxide formulation used in this study is commercially available form named as metapex which is composed of calcium hydroxide, silicon oil, and iodoform (Meta Dental Corp Ltd., Elmburt). All the samples where dried with paper points and Metapex was injected into the root canal until the material extruded through the apex and from orifice. The root canal orifices of all the specimens were later temporarily sealed with Fuji II glass ionomer cement and stored in normal saline at 37 ^oC for seven days.

The teeth were divided into 4 groups consisting of 9 teeth in each group.

Group A: 7% Maleic acid manual

Group B: 10% Sodium bicarbonate manual

Group C: 7% Maleic acid manual with ultrasoinic agitation.

Group D: 10% sodium bicarbonate manual with ultrasonic agitation

In group A 5 ml of 7% maleic acid was used to remove metapex with the help of 25 no. H file for one minute. In group B 5 ml of 10% sodium bicarbonate was used to remove metapex with the help of 25 no. H file for one minute. In group C 5 ml of 7% maleic acid was used to remove metapex with the help of combination of both manual and ultrasonic agitation and in group D, 5 ml of 10% sodium bicarbonate was used with the combination of both manual and ultrasonic agitation.

Ultrasonic agitation was done using 25 K ultrasonic file (Mani files, mani, inc Tochigi Japan) mounted on a piezoelectric hand piece (Electro Medical Systems, SA) at a power setting of 5 and was activated passively for 1 minute at 2 mm short of working length. Concentrations of 7% MA and 10% sodium bicarbonate were freshly prepared just before the experiment. Spiral CT was taken after mounting the teeth in a plastic stand using modeling wax. Siemens Emotion duo model of spiral CT with the aid of Syngo software was used for estimating the volume of the remaining material in each tooth.

The results were analysed using SPSS software Version. 17. Considering the data to be parametric ANOVA followed by Tukey’s post hoc analysis was done for comparison between all groups and pair-wise comparison.

RESULTS

Table 1 shows the comparison of the mean volume of the remaining material in the various study groups using one way analysis of variance. There was a statistically significant difference in the the mean volume of the remaining material. When pairwise comparison was done using tukey’s post hoc test, it was observed that the maximum volume of material left behind was by 7 %Maleic acid (manual) followed by 10% Sodium bicarbonate(manual), 7% Maleic acid (with ultrasonic agitation) and 10% Sodium bicarbonate (with ultrasonic agitation). Statistically significant difference between was observed between 7% Maleic acid (manual) and 7% Maleic acid (with ultrasonic agitation) as well as 7% Maleic acid (manual) and 10% Sodium bicarbonate (with ultrasonic agitation). Figure 1 shows the mean volume of the remaining material in the various study groups.

Table 1: Comparison of the volumetric analysis in the study groups using one way ANOVA

*. The mean difference is significant at p value < 0.05.

Table 2: Pairwise analysis in the study groups using Tukey’s post hoc test.

*. The mean difference is significant at p value < 0.05.

Figure 1: Comparison of the volumetric analysis in the study groups

DISCUSSION

This in vitro study was to conducted to assess the efficiency of 10% sodium bicarbonate and compare it with 7% maleic acid in removal of the commercially available paste in silicone oil named as metapex using manual method and combination of both manual and ultrasonic agitation and spiral computed tomography (CT) was used to analyze the volume of calcium hydroxide removed. In the present study, it was observed that the maximum volume of material left behind was by 7 %Maleic acid (manual) followed by 10% Sodium bicarbonate(manual), 7% Maleic acid (with ultrasonic agitation) and 10% Sodium bicarbonate (with ultrasonic agitation). Statistically significant difference between was observed between 7% Maleic acid (manual) and 7% Maleic acid (with ultrasonic agitation) as well as 7% Maleic acid (manual) and 10% Sodium bicarbonate (with ultrasonic agitation).

One of the ideal requirement of any intracanal medicament is its complete retrieval from the root canal. ^14,15 For removal of calcium hydroxide preparations several irrigants and their combinations like saline, sodium hypochlorite(NaOCl), ethylene diamine tetra-acetic acid (EDTA), EDTA with a cationic detergent (EDTA-T) , citric acid and more recently maleic acid have been used.^16-20 Among which none of the irrigants were able to completely remove the (CH + iodoform + silicone oil) mixture. This may be mainly because of the vehicle used i.e. Silicone oil which might have resisted its dissolution and removal from the root canal by test irrigants. However, it was found that 10% citric acid and 7% Maleic acid gave better results than 17% EDTA in the removal of (CH + iodoform + silicone oil) mixture.( NV Ballal et al, 2012).²¹ This finding is in accordance with a study by Mohan Thomas Nainan et al,²² 2013 who also concluded that 7% maleic acid gave better retrieval capability of Metapex than 17% EDTA.

Maleic acid because of its low surface tension and acidic nature has shown to have better results then EDTA. But still was not able to completely remove the metapex from root canal. ²² In this study 25 no. H file was used for removing metapex manually in group one and two with saline irrigation as all the samples were prepared till F 3 protaper files using x-smart rotary system.^21,23 It has been reported that passive ultrasonic irrigation is more effective in removing CH paste than syringe irrigation.¹⁷

Very few studies has been reported that combine manual and passive ultrasonic irrigation for removal of calcium hydroxide from root canals.^18,21,22. Hence in group c and d along with manual method passive ultrasonic agitation was done. In most studies, the surface area covered with calcium hydroxide after removal was analyzed using photos of specimens with digital image processor after sectioning the teeth longitudinally and analysis of.¹³

Calcium hydroxide is usually placed as an intracanal medicament for periods of 1–4 weeks. (Siqueira & Lopes 1999).⁵ Hence, in this study the specimens where stored in saline at 37^oC and retrieval of metapex has been carried out after seven days.

In our study volume analysis was done with spiral CT which gives a three-dimensional volume measurements with no need of sectioning the specimens and thus avoiding the loss of material during sectioning thereby providing a more accurate measurement of amount of post‑removal calcium hydroxide from root canals.^20-22

CONCLUSION

1. 7% Maleic acid (with ultrasonic agitation) proven to be better than (Manual).
2. 10% Sodium Bicarbonate is proven to be better both (manual) and (with ultrasonic agitation) when compared to 7% Maleic acid (Manual) and (Ultrasonic Agitation).

So, according to this study overall performance of 10% sodium bicarbonate is proven to be better than 7% Maleic acid in removal of silicon oil based preparation from root canal.