|Year : 2011 | Volume
| Issue : 1 | Page : 28-33
Comparison of antimicrobial substantivity of root canal irrigants in instrumented root canals up to 72 h: An in vitro study
MN Shahani1, VV Subba Reddy2
1 Professor, Department of Pedodontics & Preventive dentistry, Bharati Vidhyapeeth University, Dental College and Hospital, Navi Mumbai 400 614, India
2 Professor and Head, College of Dental Sciences, Davangere - 577 004, India
|Date of Web Publication||23-Apr-2011|
M N Shahani
Department of Pedodontics & Preventive dentistry, Bharati Vidhyapeeth University, Dental College and Hospital, Sector -7, C.B.D, Belpada, Navi Mumbai 400 614
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Disinfection of the root canal system is one of the primary aims of root canal treatment. This can be achieved through the use of various antimicrobial agents in the form of irrigants and medicaments. The antimicrobial substantivity of 2% chlorhexidine gluconate, 1% povidone iodine, 2.5% hydrogen peroxide followed by 2% sodium hypochlorite, and 2% sodium hypochlorite alone as irrigants was assessed in instrumented root canals. 2% chlorhexidine showed antimicrobial substantivity lasting up to 72 h, followed by 1% povidone iodine, and 2% sodium hypochlorite. Thus 2% chlorhexidine should be used as a final rinse irrigant in endodontic treatment protocols.
Keywords: Chlorhexidine, endodontics, irrigants, medicaments, substantivity
|How to cite this article:|
Shahani M N, Subba Reddy V V. Comparison of antimicrobial substantivity of root canal irrigants in instrumented root canals up to 72 h: An in vitro study. J Indian Soc Pedod Prev Dent 2011;29:28-33
|How to cite this URL:|
Shahani M N, Subba Reddy V V. Comparison of antimicrobial substantivity of root canal irrigants in instrumented root canals up to 72 h: An in vitro study. J Indian Soc Pedod Prev Dent [serial online] 2011 [cited 2020 Feb 20];29:28-33. Available from: http://www.jisppd.com/text.asp?2011/29/1/28/79925
| Introduction|| |
The essence of endodontic therapy is the restoration of the treated tooth to its proper form and function in the masticatory apparatus in a healthy state. There are three basic established phases in endodontic treatment known as 'ENDODONTIC TRIAD" comprising biomechanical preparation, irrigation and disinfection, and obturation. Every facet of the treatment is important and must be performed in a predetermined manner, if any step is faulty, entire system may fail. 
Mechanical preparation of the root canal is an important method of tissue removal. Mechanical preparation should always be followed by irrigation of the root canal to wash out the fragments of pulpal tissue and dentinal shavings. Thus, chemical debridement is a necessary adjunct to ensure complete eradication of necrotic tissue and debris.  Number of irrigating solutions with antiseptic /tissue solvent qualities includes sodium hypochlorite in various concentrations, hydrogen peroxide, chlorhexidine, urea, gly-oxide, and citric acid.  To achieve disinfection of the root canal system, it is imperative to use antiseptics as irrigants. A treatment protocol for preventing reinfection of the root canals and improving outcome of endodontic treatment is to use irrigants with residual antimicrobial activity, i.e. substantivity.  White, Hays, Janer (1997) have reported that 2% chlorhexidine gluconate (CHX) possesses in vitro substantiative antimicrobial activity equivalent to 5.25% sodium hypochlorite.  Hence, the present study was aimed to assess the period of substantiative antimicrobial activity of 2% CHX, 1% povidone iodine, 2.5% hydrogen peroxide followed by 2% sodium hypochlorite, 2% sodium hypochlorite alone as irrigants in instrumented root canals using a control group of sterile deionized water.
| Materials and Methods|| |
The present study was carried out on 50 extracted single rooted teeth which were free from caries, surface defects or root fractures in the Department of Pedodontics and Preventive Dentistry and Oral Pathology.
Random grouping of 50 teeth were done, allocating 10 to each group.
Group I-10 teeth: Irrigant 2% CHX (ICPA Health Products Pvt. Ltd) was used.
Group II-10 teeth: Irrigant 1% povidone Iodine (Win Medicare Ltd.) was used.
Group III-10 teeth; Irrigants 2.5% hydrogen peroxide (Reachem Laboratory Chemicals Pvt. Ltd) followed by 2% sodium hypochlorite was used.
Group IV-10 teeth: Irrigant 2% sodium hypochlorite (BML Chemicals) was used.
Group V -10 teeth: Sterile deionized water (Nice Laboratory) was used.
Teeth were prepared in a standardized manner by one operator. Access opening was done using high speed air rotor handpiece with round (No. 009) and straight (No. 010) diamond points. No. 10 K-file was used to violate the apex to ensure patency of the canal. Apex of the root was bevelled at 45º angle with taper fissure (No.012) diamond point. Etchant 37% phosphoric acid was applied to the apex for 30 s, followed by washing, drying with compressed air using a three-way air syringe. Optibond adhesive was applied to the apex, sealing was done with Prodigy Kerr A3 composite material, and light curing done as per manufacturer's instructions. Specimens were mounted on plaster block of 1.5"x 1" diameter. Root canals were prepared biomechanically and each canal was prepared to a size of No. 80 file. After each change in the file size, the canal was irrigated with corresponding irrigant (1 ml).Then the canals were irrigated with 3 ml of sterile, deionized water and dried with paper points. Canals were filled with sterile, deionized water and teeth placed in the humidor for a period of 6 h. This procedure was the same for all the group samples. After 6 h, endodontic paper points were put in the canal, kept for 2 min, then removed and stored in cryogenic vials at refrigerator temperature. Canals of all samples were irrigated with sterile, deionized water, and filled with it, teeth returned to the humidor for 12 h. Same procedure for sampling was repeated after 12, 24, 48 and 72 h and samples were stored in cryogenic vials.
Within 24 h of all the sampling procedures, the paper points were removed from the cryogenic vials and were placed in a clock-face pattern on the mitis salivarius-bacitracin streptomycin (MSBS) agar plates. These plates were stored in the dynamicro anaerobic chamber and incubated at 37ºC for 48 h in the incubator. At the end of 48 h, the MSBS agar plates were removed, zones of inhibition were measured with a scale in millimetres, perpendicular to the paper points using a magnifying lens. Results were tabulated and statistical analyses were carried out.
| Results|| |
Zones of inhibition in various irrigants used were measured and analyzed using "one-way analysis of variance" (ANOVA). Results showed that antimicrobial activity (inhibition) was significantly different in different irrigants. For simultaneous comparison of zones of inhibition between the different irrigants at different sample collection periods, Student t-test was used. The control group was not included in statistical analysis as no zones of inhibition were observed in any of the samples at different collection periods [Figure 1]. Throughout the sampling procedure, i.e. different collection periods (0-6 h, 6-12 hours, 12-24 h, 24-48 h, 48-72 h), the maximum zone of inhibition was shown by Group I [Figure 2], followed by Group II [Figure 3], Group IV [Figure 4], and Group III [Figure 5] [Table 1]. The inter-comparison between Groups I and II, Groups I and IV, Groups I and III throughout the sampling period (0-6 h---[Table 2]), (6-12 h---[Table 3]), (12-24 h---[Table 4]), (24-48 h---[Table 5]), (48-72 h---[Table 6]) showed statistically significant (P< 0.01) difference in zones of inhibition [Figure 6]. The inter-comparison between Groups II and I, Groups II and IV, Groups II and III throughout the sampling period (0-6 h---[Table 2]), (6-12 h---[Table 3]), (12-24 h---[Table 4]), (24-48 h---[Table 5]), (48-72 h---[Table 6]) also showed statistically significant (P< 0.01) difference in the zones of inhibition [Figure 6]. The inter-comparison between Groups III and IV throughout the sampling period did not show significant difference in the zones of inhibition [Figure 6] [Table 2],[Table 3],[Table 4],[Table 5],[Table 6].
|Table 2: Comparison of mean zones of inhibition between different irrigants at 0-6 h of collection |
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|Table 3: Comparison of mean zones of inhibition between different irrigants at 6-12 h of collection |
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|Table 4: Comparison of mean zones of inhibition between different irrigants at 12-24 h of collection |
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|Table 5: Comparison of mean zones of inhibition between different irrigants at 24-48 h of collection |
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|Table 6: Comparison of mean zones of inhibition between different irrigants at 48-72 h of collection |
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|Figure 1: Group V (deionized water - control group) not showing the zone of inhibition at 6 h, 12 h, 24 h, 48 h & 72 h interval.|
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|Figure 2: Group I (2% chlorhexidine) showing zones of inhibition at 6 h, 12 h, 24 h, 48 h & 72 h interval.|
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|Figure 3: Group II (1% povidone iodine ) showing zones of inhibition at 6 h, 12 h, 24 h, 48 h & 72 h interval.|
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|Figure 4: Group IV (2% sodium hypochlorite ) showing zones of inhibition at 6 h, 12 h, 24 h, 48 h & 72 h interval.|
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|Figure 5: Group III (2.5% hydrogen peroxide followed by 2% sodium hypochlorite ) showing zones of inhibition at 6 h, 12 h, 24 h, 48 h & 72 h.|
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Control in endodontics is largely dependent on the effectiveness of root canal debridement, since any organic residue can act as substrate for bacterial growth.  Thus, an irrigant should possess a broad antibacterial spectrum, antimicrobial substantivity, dissolve necrotic pulp tissue remnants, prevent formation of smear layer, systemically be non-toxic, non-caustic, and non-allergic.  The present study was undertaken to evaluate the substantiative antimicrobial activity of 2% CHX (Group I), 1% povidone iodine (Group II), 2.5% hydrogen peroxide followed by 2% sodium hypochlorite (Group III), 2% sodium hypochlorite (Group IV), as there are many studies performed on action of these irrigants in instrumented root canals. ,,
| Discussion|| |
2% CHX was used in the present study, as it is known to have a substantiative broad, antimicrobial spectrum, i.e. it has the ability to be adsorbed on hydroxyapatite surfaces and released from them gradually. ,,, It is effective against gram positive and gram negative bacteria as well as yeasts, but more effective against gram positive bacteria.  Hence, MSBS agar plates were used as a culture medium. The findings of the present study showed 2% CHX had substantiative antimicrobial activity that lasted up to 72 h similar to White et al,  Leonardo et al.  Studies have shown that substantivity of 2% CHX lasts for 12 weeks. , Antimicrobial substantivity depends on the number of CHX molecules available to interact with the dentine. Therefore, medicating the canal with more concentrated CHX preparation should result in increased resistance to microbial colonization. Recently, antibacterial substantitivity of three concentrations of CHX solution (4%, 2%, and 0.2%) after 5 min has been evaluated. Results revealed a direct relationship between the concentration of CHX and its substantivity.  Further research is required to determine substantivity for period longer than 12 weeks.
Povidone iodine, a complex of polyvinyl pyrrolidone and iodine in an aqueous solution, is effective against gram positive and negative organisms as well as fungi and viruses. Its antimicrobial effect is due to its vapour forming ability and low surface tension. , The result of the present study showed 1% povidone iodine had significant zone of inhibition (P< 0.01) when used as an irrigant compared to use of Group IV and Group III. However, it had statistically significant difference (P< 0.01) in zones of inhibition when compared to 2% CHX. The reason for this maybe that CHX has prolonged substantiative property, whereas povidone iodine has an antibacterial effect but does not demonstrate substantivity to exert a prolonged antimicrobial effect. 
Hydrogen peroxide is an unstable, weak antimicrobial agent. Sodium hypochlorite has been used as an irrigant for past few decades because of its several advantages, namely antimicrobial activity, pulp tissue solvent.  The present study reported that Group III and Group IV had the least zone of inhibition compared to the other irrigants used, similar to Gutierrez et al.  These agents lack substantiative antimicrobial activity to be used as endodontic irrigants alone. We have used 2% sodium hypochlorite alone as an irrigant in our study as it has been reported that it can be used safely as an endodontic irrigant at pH of 12-12.5, is non-toxic and pulp tissue solvent.  Group IV showed the least zone of inhibition compared to the other irrigants used in the study; similar to findings reported by Kuruvilla, Kamath. 
Group V used as a control, throughout the study period did not show any zone of inhibition as it had no antibacterial effect.
| Conclusions|| |
Based on the present in vitro study, it was observed that
- 2% CHX is a preferred endodontic irrigant than 1% povidone iodine, 2.5% hydrogen peroxide followed by 2% sodium hypochlorite, 2% sodium hypochlorite alone as it revealed substantiative antimicrobial activity potentially protective of the canal tissues for 72 h.
- CHX has favourable antimicrobial activity and substantivity; it should be used as a final rinse in endodontic treatment protocols.
- Further research investigations are needed to evaluate substantivity of CHX beyond 12 weeks to advocate its use as intracanal medicament in retreatment cases compared to initial endodontic infections.
- Though no studies are done evaluating 1% povidone iodine as root canal irrigant for its substantiative antimicrobial activity, the findings of the present study are encouraging as it ranked second to 2% CHX in its antimicrobial efficacy. Further in vivo studies must be conducted for advocating its use in routine clinical practise as an alternative to 2% CHX, 2% sodium hypochlorite.
- Although combined usage of 2.5% hydrogen peroxide followed by 2% sodium hypochlorite may be effective on initial exposure, it is not a substantiative antimicrobial combination for use as irrigant alone.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6]
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