New fluoride MI Varnish as root canal sealer: An in vitro analysis of bacterial leakage

Dhanu G Rao; Malay Vishnuprasad Trivedi; Raghavendra Havale; SP Shrutha

doi:10.4103/0970-4388.191418



ORIGINAL ARTICLE

Year : 2016 \| Volume : 34 \| Issue : 4 \| Page : 359-363

New fluoride MI Varnish as root canal sealer: An in vitro analysis of bacterial leakage

Dhanu G Rao, Malay Vishnuprasad Trivedi, Raghavendra Havale, SP Shrutha
Department of Pedodontics and Preventive Dentistry, AME's Dental College and Hospital and Research Center, Raichur, Karnataka, India

Date of Web Publication

29-Sep-2016

Correspondence Address:
Dhanu G Rao
Department of Pedodontics and Preventive Dentistry, AME's Dental College and Hospital and Research Center, Raichur - 584 103, Karnataka
India

Source of Support: None, Conflict of Interest: None

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DOI: 10.4103/0970-4388.191418

Abstract

Aims: The aim of the present study was to evaluate and compare the sealing ability of root canal obturation after the application of fluoride varnish (MI Varnish) containing 5% sodium fluoride and casein phosphopeptide-amorphous calcium phosphate, fluoride varnish, and AH Plus and AH-Plus as root canal sealer by bacterial penetration test. Materials and Methods: Root canals of 65 single-rooted and single-canalled teeth were prepared. They were divided into three experimental groups (n = 15) and two control groups (n = 10). The root canal walls in Group I were coated with AH Plus, Group II were coated with AH Plus and fluoride varnish, and Group III were coated with fluoride varnish. All the teeth were obturated with gutta-percha using the lateral condensation technique. Enterococcus faecalis were used as test bacteria to determine the leakage during 100 days. Statistical Analysis: The data were analyzed using log-rank test and Kaplan-Meier survival analysis. Results: Group III showed significantly less bacterial penetration as compared to Group I (P = 0.01) and Group II (P = 0.03). However, there was no statistical significance between Groups I and II (P = 0.672). Conclusions: It can be concluded from the present study that fluoride varnish can be used as a root canal sealer. However, further in vitro and in vivo studies are required.

Keywords: AH Plus, bacterial penetration, MI fluoride varnish, root canal sealer

How to cite this article:
Rao DG, Trivedi MV, Havale R, Shrutha S P. New fluoride MI Varnish as root canal sealer: An in vitro analysis of bacterial leakage. J Indian Soc Pedod Prev Dent 2016;34:359-63

How to cite this URL:
Rao DG, Trivedi MV, Havale R, Shrutha S P. New fluoride MI Varnish as root canal sealer: An in vitro analysis of bacterial leakage. J Indian Soc Pedod Prev Dent [serial online] 2016 [cited 2021 Apr 23];34:359-63. Available from: https://www.jisppd.com/text.asp?2016/34/4/359/191418

Introduction

Microorganisms are responsible for causing all pulpal and periapical diseases. ^[1],[2],[3] Bacteria and toxins have the ability to percolate the filled root canals and can enter periapical tissues. ^[4],[5] Therefore, perfect sealing of root canal system is important to prevent bacteria and their toxins from reaching the root apex.

Creating an aseptic condition with complete obturation of the pulpal space is the main aim of the root canal treatment. ^[6] The most widely used material for this purpose is gutta-percha as it is biocompatible, inert, radiopaque, stable, compressible, and can be easily retrieved with known solvents. ^[6] But the limitation is that gutta-percha does not bond to dentin and provides poor seal, so it is used in combination with root canal sealers to eliminate interface between gutta-percha and dentinal wall. ^[6],[7] However, leakage may occur between sealer and dentin, sealer and gutta-percha, and in spaces with in sealer itself. ^[8],[9] Thus, the quality of sealing depend upon the sealing ability of root canal sealers. A wide variety of root canal sealers have been used in combination with gutta-percha to provide tight seal.

Mickel et al. has conducted an in vitro study and showed that stannous fluoride inhibit the growth of Enterococcus faecalis which play major role in etiology of persistent periradicular lesions and found in high percentage in case of root canal failures. ^[10],[11]

Parirokh et al. has conducted an in vitro study and showed that after the application of fluoride varnish as root canal sealer will interfere with the recontamination of dentinal tubules and improve the root canal sealing ability. ^[12] Fluoride varnish has been used in preventing caries, for surface treatment of delayed implanted avulsed teeth, as root canal filling material in primary teeth in combination with calcium hydroxide and zinc oxide eugenol and for the treatment of delayed hypersensitivity. ^[12] Farghal et al. ^[13] has conducted an in vitro study using casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) paste on dentin and showed that CPP-ACP paste decrease the permeability of dentine.

MI Varnish (GC Dent, India) is the new varnish containing fluoride as well as CPP-ACP. It is mainly used for topical fluoride application, for remineralization and treatment of hypersensitive teeth. An electronic literature search was performed within MEDLINE (via PubMed), ScienceDirect, Web of Science, Cochrane, and ClinicalKey databases until December 2015, and it showed that no studies were performed on MI Varnish as a root canal sealer.

The aim of present study was to evaluate and compare the sealing ability of root canal obturation after the application of fluoride varnish containing 5% sodium fluoride and CPP-ACP (MI Varnish), a combination of AH Plus and MI fluoride varnish and AH Plus as root canal sealer by bacterial penetration test.

Materials and Methods

In this in vitro experiment, 65 single-rooted and single-canalled teeth were used. Teeth surfaces were cleaned with curette to remove calculus and soft tissue and stored in sodium hypochlorite (5.25%) for 1 h for surface disinfection and later rinsed with and stored in normal saline.

Access cavities of 65 teeth were prepared using high speed diamond point with water cooling. Apical patencies were determined with size 15-K file (MANI INC., Japan). The working length was visually determined 1 mm short from anatomical apical foramen. The canals were shaped and cleaned by step back technique up to size 45-K file (MANI INC., Japan) and were irrigated with 2 mL of 5.25% sodium hypochlorite (NaOCl) (Asian Acrylates, Mumbai, India) during instrumentation. Canal patency was maintained by inserting a size 15-K file by recapitulation. When instrumentation of the root canal was complete, 17% EDTA (Prime Dental Products Pvt. Ltd., Mumbai, India) was applied for 1 min to remove smear layer and the canal was irrigated with 5.25% NaOCl. The canals were dried with paper points. The prepared teeth were randomly assigned into three experimental groups (n = 15) and two control groups (n = 10) [Figure 1] and [Figure 2].

Figure 1: (a) Materials for root canal preparation. (b) Materials for root canal obturation

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Figure 2: (a) Group I: AH Plus (b) Group II: AH Plus + fluoride varnish (c) Group III: Fluoride varnish (d) Positive Control group (e) Negative control group

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Experimental groups

The root canals in Group I were filled with gutta-percha and AH-Plus sealer (Dentsply, India). The root canals in Group II were coated with fluoride varnish (MI Varnish, GC Dent, India) and then obturated with gutta-percha and AH Plus sealer. The root canals in Group III were coated with fluoride varnish as root canal sealer using spreader and then obturated with gutta-percha. For obturation of all specimens with gutta-percha, lateral condensation method was used. External surfaces of roots were covered with two layers of nail polish from coronal edge to 2 mm short of anatomic apex to prevent penetration of materials through dentinal tubules and accessory canals.

Positive controls

Positive control samples consisted of ten unfilled root canals. External surfaces of teeth roots were covered using two layers of nail polish.

Negative controls

Negative control samples consisted of ten samples and were obturated without sealer and covered completely with two layers of nail polish including apical portion.

Sample preparation

The samples were sterilized in autoclave. To receive the sample, air tight glass bottles were used with rubber stoppers. The glass bottles were filled with sterile brain heart infusion (BHI) broth (Hi-Media Laboratories Pvt. Ltd., Mumbai, India) with phenol red dye, which acted as an indicator. Holes were made in the stoppers of air tight glass bottles and teeth were inserted under high pressure through the stoppers in such a way that apical portion of root was immersed in liquid. Each specimen was sealed with cyanoacrylate glue to prevent leakage at connection zone. This whole system was again sterilized in autoclave. Any test apparatus that showed signs of turbidity in the BHI broth was discarded.

Bacteria penetration and inoculation

E. faecalis were obtained from the Microbiology Department of AME Dental College and Hospital. The coronal chambers of each specimen were inoculated with 0.5 ml of BHI containing 10 ⁶ E. faecalis per 1 ml using sterile syringe and 23-guage needle. The medium with microorganisms was changed every 3 days up to 100 days. The systems were stored in incubator at 37°C and color change of culture (from red to yellow) in the apical chamber was checked every day for a period of 100 days. The time taken for this color change was recorded as an indicator of coronal contamination [Figure 3]. Microorganisms in apical chamber were identified using gram-stain and catalase test. Double blinding was done during the observations of color change of the samples for 100 days.

Figure 3: Color change from red to yellow (a) uncontaminated (b) contaminated

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Data were subjected for statistical analysis using log-rank test for pair wise comparison of groups and Kaplan-Meier survival analysis for calculating median time of leakage. All statistical analysis were done in excel and P value of 0.05 was considered as statistically significant.

Results

The samples in positive control group showed bacterial penetration after 1 day, whereas the negative controls remain uncontaminated throughout the observational period.

Group I showed highest amount of leakage of about 56% (8 samples), Group II showed 40% of leakage (6 samples), and Group III showed least amount of leakage of about 20% (2 samples) [Table 1]. The first appearance of bacterial penetration was seen on 26 ^th day for Groups I and II and 25 ^th day for group for Group III.

Table 1: Frequency and mean of bacterial penetration in different groups

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The average time for bacterial penetration among experimental groups was highest in Group I followed by Groups II and III [Table 1].

The Kaplan-Meier survival test [Figure 4] showed that there were significant differences between bacterial penetration in Group III in comparison with Group I (P = 0.01) and Group II (P = 0.03), but there was also no significant difference between Groups I and II (P = 0.672).

Figure 4: Bacterial penetration among different groups

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Discussion

The results of present study have shown that when MI fluoride varnish was used as a root canal sealer for obturation, there was improvement in root canal sealing ability.

To gain clinical success in endodontic therapy, tight seal in either apical or coronal region of root canal is essential. ^[6] Numerous studies have been done to assess in vitro leakage including penetration of tracers such as dye, radioisotopes, microorganisms and their toxins, and fluid filtration or transportation method. ^[12] According to Timpawat et al., ^[7] the use of bacteria to assess leakage (mainly coronal) is considered to be of greater clinical and biological significance than the dye penetration method. In this study, bacterial penetration method was used because it is most commonly used and clinically appropriate method used to assess sealing ability of root canal sealers.

Shahravan et al. ^[14] has conducted an in vitro study and showed that smear layer removal will improved the seal of root canal obturation. Therefore, in the present study, smear layer was removed prior to obturation.

Facultative bacteria are predominantly found in previously failed root canal treatment with the most frequently isolated bacteria being enterococci. E. faecalis are part of normal micro flora in humans and frequently found in mixed infections with other aerobes and anerobes. ^[12] Therefore, E. faecalis was selected as test bacteria for the evaluation of leakage in the present study.

Numerous studies have been conducted on bacterial leakage and they have shown that average time for total bacterial penetration can be similar for all groups or there can be variation among all groups. ^{[15],[16],[17],[18]} Yücel et al., 2006, ^[16] compared bacterial penetration between four different root canal sealers (AH 26, AH Plus, Sealapex and Ketac Endo) and found variations in timings for total bacterial penetration among groups. In an in vitro study, Parirokh et al. ^[12] used fluoride varnish, AH 26, and combinations of AH 26 and fluoride varnish as root canal sealers and showed variations in timings for bacterial leakage between these groups. In present study also, there were variations among groups for bacterial leakage (74.5 days for Group I, 65.7 days for Group II, and 35 days for Group III). Saunders et al. ^[18] believed that the difference of time for bacterial penetration of the experimental groups can possibly be attributed to variable root canal anatomy, shape of canal preparation, and sealer type. In the present study, due to similar method of root canal preparation and comparable root anatomy, the differences in bacterial penetration among the experimental groups can be attributed to the difference in root canal sealing method.

AH Plus is looked as a bench mark ("Gold Standard") due to its excellent properties, such as low solubility, small expansion, adhesion to dentin, and its very good sealing ability. Therefore, in the present study, AH Plus sealer was used for comparison. ^[19]

Mickel et al. ^[10] has conducted an in vitro study and showed that stannous fluoride inhibited the growth of E. faecalis significantly more than calcium hydroxide and a combination of both. They suggested that stannous fluoride might be a good material as an intracanal medicament between appointments. ^[10] Sen and Büyükyilmaz ^[20] evaluated the effect of 4% titanium tetrafluoride solution on root canal walls using scanning electron microscopy (SEM). Results of SEM images showed that fluoride solution occludes the dentinal tubules and they concluded that using titanium tetrafluoride solution might prevent recontamination of dentinal tubules. Parirokh et al. ^[12] has performed an in vitro study by using fluoride varnish as root canal sealer and showed reasonable root canal sealing ability of fluoride varnish as compared to AH-26 root canal sealer. Farghal et al. ^[13] has conducted an in vitro study and showed that CPP-ACP paste decrease the permeability of dentine by partial occlusion of dentinal tubules and subsurface deposition of CPP-ACP crystals in dentinal tubules. In the present study, MI fluoride varnish containing 5% sodium fluoride and CPP-ACP was used as root canal sealer and showed improved sealing ability as compared to AH-Plus and combination of AH Plus and fluoride varnish.

Conclusions

MI fluoride varnish can be used as an effective root canal sealer with reasonably improved sealing ability as compared to AH Plus and combination of AH-Plus and MI fluoride varnish. Further in vivo and in vitro studies are needed to evaluate the physical properties and biocompatibility of material.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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