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Year : 2010  |  Volume : 21  |  Issue : 4  |  Page : 523-527
Comparison of 2% chlorhexidine and 5.25% sodium hypochlorite irrigating solutions on postoperative pain: A randomized clinical trial

Department of Conservative Dentistry & Endodontics, The Oxford Dental College & Hospital, Bangalore, Karnataka, India

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Date of Submission18-Nov-2009
Date of Decision03-Apr-2010
Date of Acceptance16-Aug-2010
Date of Web Publication24-Dec-2010


Aim: To compare the levels of postoperative pain after cleaning and shaping of root canals using two different root canal irrigants for debridement.
Materials and Methods: Forty patients with irreversible pulpitis, pulp necrosis and non-vital teeth exhibiting acute apical periodontitis requiring root canal treatment were included. At random, canals were cleaned and shaped with the following protocols. 2% chlorhexidine solution in group I and 5.25% sodium hypochlorite solution in group II were used as an irrigants. Access cavities were closed with a sterile cotton pellet and cavit. The patients recorded degree of pain at various time intervals after cleaning and shaping on a visual analogue scale for 1 week.
Results: The mean pain score for group I was between 0.65 and 3.35 and for group II was between 0.95 and 4.50. There was significant difference in the pain level between the two groups only at 6 th hour postoperatively (P<0.05) and the pain was more in sodium hypochlorite group.
Conclusions: More pain was present in teeth irrigated using 5.25% sodium hypochlorite when compared to that in teeth irrigated using 2% chlorhexidine solution. Significant difference in pain level was present only at 6th hour postoperatively, and at all other periods (24 th hour, 4 th and 7 th days) there was no significant difference in pain level between the two groups.

Keywords: Chlorhexidine solution, endodontic pain, postoperative discomfort, sodium hypochlorite solution, visual analogue scale

How to cite this article:
Bashetty K, Hegde J. Comparison of 2% chlorhexidine and 5.25% sodium hypochlorite irrigating solutions on postoperative pain: A randomized clinical trial. Indian J Dent Res 2010;21:523-7

How to cite this URL:
Bashetty K, Hegde J. Comparison of 2% chlorhexidine and 5.25% sodium hypochlorite irrigating solutions on postoperative pain: A randomized clinical trial. Indian J Dent Res [serial online] 2010 [cited 2019 Aug 21];21:523-7. Available from:
Knowledge on the causes of and the mechanisms behind inter-appointment pain in endodontics is of utmost importance for the clinicians to properly prevent or manage this undesirable condition. The causative factors of inter-appointment pain encompass mechanical, chemical and/or microbial injury to the pulp or periradicular tissues, which are induced or exacerbated during root canal treatment. [1] One of the aims of root canal treatment is to eliminate the bacteria, their by-products and the substrate from the root canal system. A number of antimicrobial irrigants have been recommended for cleaning and shaping of root canals. These materials are frequently placed in intimate contact with the tissues of the periodontium. Most irrigants and medications are cytotoxic to the host tissues, and consequently, there is virtually a universal consensus that their use should be restricted to the root canal. Clinical trials have shown that substances used for irrigation or intracanal medication may have no influence on the occurrence of postoperative symptoms. However, severe reactions have been reported after extrusion of some commonly used substances to the periradicular tissues. [2] It is highly desirable that the chemical agents selected as an endodontic irrigants possess four major properties: antimicrobial activity, dissolution of organic tissues, aid in debridement of the canal system and nontoxicity to periapical tissues. [3]

The most popular endodontic irrigant is 5.25% sodium hypochlorite (NaOCl), which has been used well over four decades. Although it is an effective antimicrobial agent and an excellent organic solvent, [4] it is known to be highly irritating to the periapical tissues, [5] mainly at high concentrations. For this reason, the search for another irrigant with a lower potential to induce adverse effects is desirable. Many attempts have been made to find other efficient irrigants with a high antimicrobial action and low toxicity.

2% Chlorhexidine gluconate (CHX) has been suggested as an alternative irrigating solution that could replace NaOCl. CHX is a cationic bisguanide that seems to act by adsorbing onto the cell wall of the microorganism and causing leakage of intracellular components. At low concentration, CHX has a bacteriostatic effect and at high concentration it has a bactericidal effect because of precipitation and/or coagulation of intracellular constituents. [6] Its optimal antimicrobial activity is at pH 5.5-7.0. [7] CHX has a broad-spectrum antimicrobial activity, targeting both gram-positive and gram-negative microbes. [8] In general, in vitro studies suggested that CHX and NaOCl have comparable antibacterial effect when used in similar concentrations. [9] In addition, CHX appeared to be a promising agent as a final irrigant. In a clinical study, Zamany et al. [10] showed that a 2% CHX solution, used as a final irrigant, significantly decreased bacterial loads in root canals that had been irrigated with sodium hypochlorite during canal preparation. Additional advantages of CHX are its retentive character in root canal dentin, [11] its relatively low toxicity, [12] more tolerable odor and taste and nonbleaching effect. Despite its advantages, CHX activity is pH dependent and is greatly reduced in the presence of organic matter. [7] Unlike sodium hypochlorite, it lacks tissue dissolving properties. [13]

Though it shows promising results from in vitro studies, there are not enough clinical studies published so far to evaluate the effect of 2% CHX on postoperative pain when used as an irrigant. So, the purpose of this study was to compare postoperative pain caused due to change in the bacterial load during disinfection, following irrigation using 5.25% NaOCl and 2% chlorhexidine solutions. The study was started with null's hypotheses that there will be no difference in the postoperative pain level caused by 5.25% NaOCl and 2% chlorhexidine solutions when used as irrigants.

   Materials and Methods Top

The outline of this clinical trial was approved by the ethical Committee of The Oxford Dental College, Hospital and Research Centre, Bangalore.

Patient selection

Patients presenting to the endodontic clinic at The Oxford Dental College, Hospital and Research Centre, Bangalore, for evaluation and treatment of decayed teeth were considered. For this clinical evaluation, 40 mandibular first premolars of 40 patients of age range 21-40 years were selected. The sample size was estimated based on the secondary data. The clinical trial was confined to the teeth with irreversible pulpitis, necrosed pulp and nonvital teeth exhibiting acute apical periodontitis. Patients with history of allergy to any medications, retreatment cases, patients who were taking medications for pain were excluded. Also excluded were patients with acute abscess. All root canal treatments were completed in two visits and all procedures were undertaken by one endodontic resident in the Department of Endodontics, The Oxford Dental College and Hospital, Bangalore.


Health histories consisting of demographic data, medical and dental histories and chief complaints were obtained from all patients participating in this study. Clinical and radiographic information was recorded for each tooth that was included in the study. After clinical examination and exposure of periapical radiographs, pulpal and periradicular diagnoses were made.

At each patient's initial consultation appointment, the nature of the investigation and the potential risks and benefits associated with the study were explained and informed consent was taken. Random assignment by coin toss method was done by another endodontic resident, who enrolled participants and also assigned them to their groups.

At the first appointment, the teeth were reduced out of occlusion. The tooth was anaesthetized, isolated with rubber dam and access gained to the root canal system. Following complete access, the canal orifices were enlarged using orifice shapers. Initial glide path was obtained by using #10 K-file of 0.02 taper. Working lengths were determined with an apex locator (Root ZX; J Morita Mfg. Corp, Kyoto, Japan) and confirmed radiographically. The root canals were instrumented in a crown-down technique with profile series (Dentsply, Tulsa Dental, Oklahoma, Japan) to an apical ISO size of 30 using two different root canal irrigants. In group I, 2% chlorhexidine solution (Consepsis, Ultra dent, South Jordan, Utah 84095, USA) and in group II, 5.25% NaOCl (sodium hypochlorite) were used as an endodontic irrigants. All root canals were irrigated with 30-gauge Max-i-Probe syringe that had been placed down the canal and 3 mm short from apex. All canals were then dried using sterile paper points. After placing a dry sterile cotton pellet in the pulp chamber of each tooth, the access cavity was closed with cavit temporary restoration (ESPE Dental AG, Seefeld, Germany). No intracanal medications were placed in any of the teeth in this study.

Evaluation after cleaning and shaping

The patients assessed their severity of pain using a modified visual analogue scale (VAS), as described by Habib et al. [14] [Table 1]. The patients recorded their degree of pain at procedure, at 6 and 24 hours, and on 4 th and 7 th days after the cleaning and shaping. Seven days after the first visit, another clinical evaluation was performed to assess the status of the periapical region using routine palpation and percussion tests. At this second visit, all patients returned the completed questionnaires to the operator. Assessment of completed questionnaires was carried out by a different endodontic resident. This was a triple blinded study in which the study participants including patients, endodontic residents and statistician were blinded.
Table 1: Assessment of postoperative discomfort by VAS*

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Premature termination of therapy

Patients who had severe pain or discomfort, swelling and other side effects after their instrumentation appointment could contact endodontic resident to receive advice or medication(s). Upon returning, the data up to the time that they dropped out from the study and started taking medication(s) were planned to be included for these patients. In the current study, no drop outs were there.

Statistical analysis

The preoperative pain scores and other preoperative factors were compared between groups using Chi-square and Fisher exact test. Mann Whitney U test was used to find the significance between two groups and Friedman test for repeated measures was used to find the significance within each group. The statistical software programs, namely SPSS 15.0, Stata 8.0, MedCalc 9.0.1 and Systat 11.0, were used for the analysis of the data and Microsoft word and Excel were used to generate graphs, tables etc. The confidence interval for our study was 95%, with 5% level of significance.

   Results Top

None of the patients developed severe swelling, pain or other side effects necessitating removal from the study. [Table 2] shows preoperative pain as well as diagnosis for both the groups. With respect to pulpal diagnosis, there was significantly more number of teeth with irreversible pulpitis in group I (P=0.077) and with necrotic pulps in group II (P=0.047). With regard to the periradicular diagnosis, no significant differences were found between the two groups (P=0.744). The VAS scores for group I lie in between 0.65 and 3.35, whereas the VAS scores for group II lie in between 0.95 and 4.5 [Table 3]. When the mean VAS scores at individual period (pre-op, procedure, 6 th and 24 hours, 4 th and 7 th days) were compared between the two groups, only at 6th hour postoperatively, statistically significant difference was observed (P=0.006) and more pain was associated with NaOCl group. Friedman test for repeated measures showed that there was a highly significant change (P<0.001) in the mean pain scores over time for both the groups. [Figure 1] shows that in group I the linear decrease of pain score was significant, while in group II, it increased postoperatively at 6 th hour and then significantly reduced on 7 th day. The power of this study was found to be 0.84%.
Table 2: Findings of group I and group II

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Table 3: Comparison of mean VAS scores between the two groups

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Figure 1: Means plot of discomfort over time for both treatment groups

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   Discussion Top

Complete preparation of the root canal space is one of the important stages in endodontic treatment. Irrigation is a necessary and important phase of cleaning the canal, but it leads to extrusion. [15] Therefore, it is logical to assume that root canal irrigant be nontoxic and biocompatible with its surrounding host tissues so that it does not contribute to postoperative discomfort. However, all the currently available antimicrobial materials for irrigation have some limitations and search continues for the ideal irrigant.

Debris extrusion is a problem with all instrumentation techniques; however, crown-down instrumentation technique [16] and the balanced force techniques [17] cause less extrusion than others. Profile instruments induce less extrusion of debris and irrigant than step-back technique. [18] Early flaring of canal walls would decrease the potential for positive hydrostatic pressure being directed apically by establishing an adequate escape. [19] All coronal-to-apical enlargement techniques support this procedure to avoid the passage of material into the periapical tissues. Hence, in this study, all preparations were done by crown-down technique using Profile system and working length was kept 1 mm short of canal length which contributed to significantly less debris extrusion. [20]

Previous investigations examined the influence of a variety of factors such as age, gender, tooth type, presence of allergy or systemic diseases, size of periradicular lesion, preoperative pain, intracanal medications, level of instrumentation and presence of sinus tract stomas. [21],[22] The contribution of these factors to the incidence of pain remains controversial. In this study, age, tooth type and level of instrumentation were standardized and the patients with allergy or systemic diseases, periradicular lesion and presence of sinus tract stomas were excluded to minimize their influence on postoperative pain factor.

It is well known that pain perception is a highly subjective and variable experience modulated by multiple physical and psychological factors. Pain reporting is influenced by many factors other than the experimental procedure. Despite the effects of a number of factors influencing patient reaction to pain, the use of the VAS to evaluate severity of pain is well established. [14] When properly designed and administered, VAS is considered to be a valid and reliable ratio scale instrument for the measurement of human pain intensity and unpleasantness. [23]

The data from the present study show that endodontic treatment resulted in a significant change in the mean pain scores over time for both the treatment groups. These findings are consistent with those of other clinical trials which have demonstrated a significant reduction in pain after root canal treatment. [22],[24] The observations from these studies underscore the effectiveness of root canal treatment for pain relief.

The results of this clinical investigation show highly significant difference in the incidence of postoperative pain between the two groups at the 6 th hour. Pain was present more in NaOCl group compared to CHX group and the reason for this may be attributed to the fact that more number of cases with necrotic pulp were present in this group. It has been proved that in necrotic cases, the irrigant may go beyond the instrumented area, [25] whereas in vital cases irrigant is forced only in the space created by instrumentation. Forced irrigation of sodium hypochlorite beyond the apex of the tooth can cause violent tissue reactions and unbearable pain. In one of the studies, [26] 2% chlorhexidine was used for subgingival irrigation and it was not toxic to the periodontal tissues at this concentration. In a retrospective study, the flare-up rate was evaluated in patients treated in multiple visits and it was concluded that a positive correlation was present between flare-ups and teeth with necrotic pulp. [27] On the contrary, Segura-Egea et al. [28] demonstrated that root canal treatment in teeth with irreversible pulpitis and acute apical periodontitis was significantly more painful than that in teeth with necrotic pulp and chronic apical periodontitis. However, Harrison et al. [29] reported no association with inter-appointment or post root canal treatment obturation pain and tooth diagnosis.

Even though the mean VAS score was more for CHX group during preoperative and procedure time compared to NaOCl, it decreased gradually from 6 th hour to 7 th day. The probable reason for less pain with progress of time in chlorhexidine group may be its substantivity effect. In vitro studies have shown that CHX exhibits sustained antimicrobial activity in the root canal for 72 hours after being used as an endodontic irrigant. [30] However, Rosenthal et al. [11] found that the treatment with a 2% CHX solution induced substantivity for up to 12 weeks.

Within the limitations of this study, significant difference in post-operative pain was observed between 2% chlorhexidine and 5.25% sodium hypochlorite solutions only at 6 th hour post-operatively, but with caution they should be considered for application or practice. Even though the pain was more at 6 th hour postoperatively in 5.25% NaOCl group, its efficiency cannot be questioned because of its important property like tissue dissolving, and hence, the long-term results of root canal treatment. Further studies are needed to compare the level of postoperative pain caused by 2% chlorhexidine solution and 5.25% NaOCl in teeth with incomplete root apices where there are more chances of periapical extrusion of irrigants. Microbiological assessment of the root canals following these two irrigants should also be done to know the role of microorganisms in causing endodontic post-treatment pain. The contribution of uneven distribution of pulpal and periradicular conditions in both the groups to the overall results could not be investigated in this study and needs further investigation.

   Conclusion Top

Significant difference in the pain level was observed between 2% chlorhexidine and 5.25% sodium hypochlorite only at 6 th hour postoperatively. Pain was present more in sodium hypochlorite group compared to chlorhexidine group.

   Acknowledgment Top

The authors would like to acknowledge Dr. Reshmi G and Late Dr. Gururaj Nadig for their help.

   References Top

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11.Rosenthal S, Spangberg I, Safavi K. Chlorhexidine substantivity in root canal dentin. Oral Surg Oral Med Oral Pathol 2004;98:518-23.  Back to cited text no. 11
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14.Habib S, Matheus RW, Scully S, Levers BG, Shepherd JP. A study of the comparative efficacy of four common analgesics in the control of post-surgical dental pain. Oral Surg Oral Med Oral Pathol 1990;70:559-63.  Back to cited text no. 14
15.Vande Visse JE, Brilliant JD. Effect of the irrigation on the production of extruded material at the root apex during instrumentation. J Endod 1975;1:243-6.  Back to cited text no. 15
16.Ruiz-Hubbard EE, Guttman JC, Wagner MJ. A quantitative assessment of canal debris forced periapically during root canal instrumentation using two different techniques. J Endod 1987;13:554.  Back to cited text no. 16
17.MCkendry DJ. Comparison of balanced forces, endosonics and step-back filling instrumentation techniques: quantification of extruded apical debris. J Endod 1990;16:24.  Back to cited text no. 17
18.Ferraz CCR, Gomes NV, Gomes BPFA, Zaia AA, Taxiera FB, Souza-Filho FJ. Apical extrusion of debris and irrigants using two hand three engine-driven instrumentation techniques. Int Endod J 2001;34:354-8.  Back to cited text no. 18
19.Hession RW. Endodontic morphology. Part 2- Canal preparation. Oral Surg Oral Med Oral Pathol 1977;44:775-85.  Back to cited text no. 19
20.Myers GL, Montgomery S. A comparison of weights of debris extruded apically by conventional filing and canal master techniques. J Endod 1991;17:275-9.  Back to cited text no. 20
21.Torabinejad M, Kettering O, McGraw C, Cummings R, Dwyer TG, Tobas S. Factors associated with endodontic interappointment emergencies of teeth with necrotic pulps. J Endod 1988;14:261-6.  Back to cited text no. 21
22.Genet JM, Wesselink PR. The incidence of preoperative and postoperative pain in endodontic therapy. Int Endod J 1988;19:221-9.  Back to cited text no. 22
23.Price DD, MC Grath PA, Rafii A, Buckingham B. The validation of visual analogue scale as ratio scale measures for chronic and experimental pain. Pain 1983;17:45-56.  Back to cited text no. 23
24.Torabinejad M, Cymerman J, Frankson M, Lemon RR, Maggio JD, Schielder H. Effectiveness of various medications on post operative pain following complete instrumentation. J Endod 1994;20:345-54.  Back to cited text no. 24
25.Salzgaber RM, Brilliant JD. An in vivo evaluation of the penetration of an irrigating solution in root canals. J Endod 1977;3:394.  Back to cited text no. 25
26.Southward SR, Drisko CL, Killoy WS, Cobb CM, Tira DE. The effect of 2.0% chlorhexidine irrigation on clinical parameters and the level of Bacteroides gingivalis in periodontal pockets. J Periodontol 1989;60:302-9.  Back to cited text no. 26
27.Mor C, Rotstei I, Friedman S. Incidence of interappointment emergency associated with endodontic therapy. J Endod 1992;18:509.  Back to cited text no. 27
28.Segura-Egea JJ, Cisneros-Cabello R, Llamas-Carreras JM, Velasco-Ortega E. Pain associated with root canal treatment. Int Endod J 2009;42:614-20.  Back to cited text no. 28
29.Harrison JW, Baumgartner JC, Svec TA. Incidence of pain associated with clinical factors during and after root canal therapy: Part-I Interappointment pain. J Endod 1983;9:384-7.  Back to cited text no. 29
30.White RR, Hays GL, Janer LR. Residual antimicrobial activity after canal irrigation with Chlorhexidine. J Endod 1997;23:229-31.  Back to cited text no. 30

Correspondence Address:
Kusum Bashetty
Department of Conservative Dentistry & Endodontics, The Oxford Dental College & Hospital, Bangalore, Karnataka
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0970-9290.74225

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  [Figure 1]

  [Table 1], [Table 2], [Table 3]

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