Frequency of Interappointment Pain Observed with Sodiumhypochlorite and Hydrogen Peroxide based Root Canal

Frequency of Interappointment Pain Observed with Sodiumhypochlorite and Hydrogen Peroxide based Root Canal
Laila Sangi1, FerozeAliKalhoro2, NareshKumar3, MuhammadArif Shaikh4

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J PakDentAssoc. 2011 (4) : 211-215


To compare the frequency of interappointment pain between 2.5% Sodium Hypochlorite and 3% Hydrogen Peroxide as a root canal irrigationmaterial. Design:Clinical trial.
Setting: Study was conducted at Dental OPD, Liaquat University of Medical and Health Sciences, Jamshoro, Pakistan fromFebruary 2009 to July 2009.


Sixty single-rooted, single-canal permanent teeth of sixty patients were selected randomly and equally divided in two groups. In groupA(n=30), 2.5%Sodiumhypochlorite (NaOCl)was used as an irrigation material while in group B (n=30), 3% Hydrogen peroxide (H2O2) was used. Canals were left empty for 72 hrs between visits. On second visit, interappointment pain was scored onVisualAnalogue Scale (VAS) (0= No pain,1- 3=mild, 4-6=moderate, 7-10= severe) by each patient on the proforma provided.


Interappointment pain was observed in 32/60 patients and the rest did not experience any pain. Pain was significantly high in group B thanA(70% vs. 36.7%; p=0.01). Severity of pain was also compared which was significantly high in group B than group A (p<0.012). Female experience more pain as compared to male.While correlation of agewith painwas not found (p>0.05).


NaOCl performed better clinically in terms of inter appointment pain when compared with H2O2.


Hydrogen Peroxide (H2O2), Interappointment pain, Root canal Irrigants, Sodium Hypochlorite (NaOCl),VisualAnalogue Scale (VAS).



nterappointment pain is a disappointing experience for the patient as well as for the dentist as it costs sometimes an unscheduled visit or unsatisfactory prediction of prognosis of root canal treatment by the patient. It is important for us to understand the causes of interappointment pain which may aid to reduce its frequency during root canal treatment. The causative factors include chemical, mechanical and most important of all microbial factor. Several factors are individually or collectively responsible for pain development by infectious agent due to an imbalance in host-bacteria relationship induced by intracanal procedures. These factors include (a) certain species of bacteria responsible for flareup, (b) prominence of virulent clones, (c) environmental condition responsible for turning on or off the expression of certain virulent clones, (d) host resistance. This leads us to the importance of the antimicrobial irrigation material during mechanical instrumentation of root canal.

The root canal irrigation serves to neutralize bacteria, inactivates bacterial toxins, dissolves necrotic pulpal tissue, lubricates canal during instrumentation, and reaches those areas which are otherwise inaccessible for mechanical instrumentation.

The interappointment pain between 2.5%NaOCl and 3% H2O2 as an irrigation material has been investigated in the current study. The previous studies were mostly done to investigate different effects of irrigant like antimicrobial properties, tissue dissolving capabilities and effect on dentine. But the association of interappointment painwith root canal irrigants needs to be investigated. So we tried in current study to find out a root canal irrigantwith less interappointment pain.

Therefore the current study is to test the null hypothesis that there would be no difference in the frequency of interappointment pain using 2.5% NaOCl and3%H2O2 as root canal irrigants.


Sixty patients with single-rooted, non-vital teeth of either gender attending for dental treatment were selected at Dental OPD, LiaquatUniversity ofMedical and Health Sciences teaching Hospital, Jamshoro, Pakistan. Complete history, clinical examination, vitality test with compressed refrigerant spray, dichloro-difluoro-methane (Endo-Frost, Roeko, Langenau, Germany), and preoperative radiographwas taken to discriminate the non vital teeth. Teeth with resorbed roots, mobile teeth and teeth with open apices, and periapical radiolucencies were excluded.The purpose of study, risks, and benefits of the materials used were explained to the patients and a signed consentwas obtained fromeach patient.

Patients were then divided randomly by lottery method into two groups. Group A (n=30) were treated with 2.5% NaOCl (Endo Wash, Star International, Washington DC, USA) and Group B (n=30) were treated with 3% H2O2 made by diluting 6% H2O2 (6% H2O2 w/n, Shahbaz Laboratories SITE B/8 Hyderabad, Pakistan)with distilledwater.

After obtaining the anesthesia, the access to the tooth was made with round and then straight fissure burs (Mani, Japan) respectively. Working length was estimated and then confirmed with radiographs. Coronal flaring was done with G.G burs (Mani, Japan) and remaining canal was preparedwith step back technique on all teeth.During canal preparation, canals were treated with respective irrigation material of that group.After preparation, canals were subsequently dried with paper points and left empty. The pulp chamber was then closed with sterile cotton and cavit (Provis, Favodent, Germany). All the cases were performed and assessed by a single operator.

Second appointment was scheduled after 72 hrs. Patients were then asked about their pain and any emergency treatment if needed. Each patient was then asked to mark on the VisualAnalogue scale according to the severity of pain (0= No pain, 1-3= mild, 4-6= moderate, 7-10= severe) on the proforma provided. The treatment of each patientwas then completed accordingly.

Data Analysis Procedure

The statistical package for social science (version 13.0, SPSS Inc., Chicago, IL, USA) was used to analyze data. Evaluation of the frequency of interappointment pain was determined by Visual Analogue Scale as: yes (VAS ranging from 1 to 10) and no (VAS = 0), and the intensity of pain considered was t e highest score recorded (1 to 3=mild, 4 to 6=moderate and 7 to 10 severe). Frequency of the variables namely gender and age groups of the patients were also computed.Mean with standard deviation, 95% confidence interval,median with IQR were computed for age and inter appointment pain.

Chi-square test was applied to compare interappointment pain and severity of pain between groups. Independent sample t test was used to compare mean difference between groups for age. Stratification of age and gender were also done to observe an effect of interappointment pain. P<0.05 was considered level of significance.


Frequency of interappointment pain was observed in 53.3% (32/60) patients. Interappointment pain was significantly higher in group B compared with group A (7 0% vs . 36.7%; p=0.01) . Compa ri son of interappointment pain between groups is presented in table 2.

Comparison of severity of interappointment pain in multi-visit root canal treatment,mild painwas bserved in3(5%) patients,moderate pain was in 21(35%) and severe pain was observed in 8(13.3%) patients. Severity of pain was significantly higher in group B than group A (chisquare = 10.93,DF=1; p<0.012). Patients distribution according to age groups and gender is shown in table 1.

Minimum age of the patients was 14 years and maximum age was 55 years. The average age of the patientswas 29.15 ± 10.33 years (95%CI: 26.48 to 31.82). The average interappointment pain score was 2.87 ± 2.91 (95%CI: 2.12 to 3.62). Proportion of genderwas similar in both groups. Similarly mean age was also not significant between the groups (p=0.87). Comparison of interappointment pain between groups with respect to gender and age group is presented in table 3.

Pain was significantly high between group in female while significant difference was not observed in male. Severe and moderate pain was high in female. Pain was not significant between groups in all ages (p>0.05).


Antimicrobial irrigation supplementing the preparation of root canal has always been a subject of interest when success of endodontic treatment is questioned.NaOCl has already found a good place among different irrigationmaterials In current study, a well-known irrigation material namely NaOCl was compared with H O . Standard concentration established by some previous studies that is 3%forH O , and 2.5%forNaOCl, were used .

The cleaning of root canals were evaluated clinically by checking interappointment pain through Visual Analogue Scale (VAS) as proposed by Seymour et al Current study confirmed that NaOCl performed significantly better thanH O in terms of interappointment pain. Ringel et al compared 2.5% NaOCl with 2% chlorhexidene in an in vivo study and the authors observed the effectiveness of NaOCl as an irrigation material.

Naenni et al. also concluded in his study that NaOCl showed effective necrotic tissue dissolution among 10 % chlorhexidene, 3 % H O , 10 % peracetic acid, 5 % dichloroisocyanurate (NaDCC), and 10% citric acid. So effectiveness of NaOCl is dependent on its ability to dissolute organicmatterwithin pulp cavity. Moreover, its strong antibacterial effect exerted by formation of hypochlorous acid, responsible for inactivating important metabolic enzymes thus killing bacterial cells. Sensitivity of DNA synthesis to hypochlorous acid (HOCl) has also been reported. Finally, it acts as a lubricant, thus flushing loose debris out of root canal. On contrary, few clinical studies have evidenced the use of NaOCl to be less effective Clinically H O exhibited less interappointment pain when compared with NaOCl as an irrigation material. In vitro study by Vijaykumar et al. demonstrated 60% negative culture with 3% NaOCl, 33.3% with H O and 70% when combination of H O + NaOCl is used as an irrigation material. Similarly Ercan et al. concluded limited success of 3% H O in eliminating bacteria from root canal in a vivo study, which is in agreementwith the findings of Patterson C.J.W et al. Other investigators, shared low effectiveness of H O , but when used with Clorhexidene their efficiency increased. But they added that the efficiency of combination decreaseswith time.

Besides the choice of irrigation material used, age and gender can have significant influence over development of interappointment pain. Interappointment pain is significantly high between groups in female while significant difference was not observed in male. Severe and moderate pain was noticed high in females. Similar results can be seen in several other studies in which large numbers of patientswere evaluated and investigators have found more flare-ups in females. But when considering the overall incidence of comparatively high frequency of pain in females, it is uncertain whether the differences are statistically significant and a meta-analysis from these studies has not yet been performed. It is reasonable that females would be more likely to seek treatment when experiencing significant symptoms. This has been consistently demonstrated in investigations that compare male and female behavior when pain is a factor. Age is not observed to be a significant factor (p>0.05) in current study. Similarly some other investigations have also failed to find any evidence Itwas also observed that the overall incidence of pain is 32/60 which is higher than expected from literature review of different researchers. One possible explanation could be that the canals were left empty (without intracanalmedicaments) between the visits in both groups. So, the high incidence of pain noticed in the study can be justified by saying that there may be some residual bacteria in the canal which can re-multiply between appointments to nearly original level to produce pain.We will refer to the conclusion of different in vitro studies and studies reporting the microbiological status of canal after antimicrobial irrigation who noticed the presence of bacteria at the end of appointment. The number of persisting bacterial cells are usually low, but these remaining bacteria can recover and rapidly increasing in number between treatment visits if no antibacterial dressing is present in the root canal. So it may be possible that irrigation significantly reduces the number of bacteria but does not make canal completely free of bacteria. That can also be supported through the results of the present study in which pain was found less when NaOCl used to clean the canal as it’s proved powerful antimicrobial agent as compared to H O . Bystrom and Sundqvist have demonstrated that chemo-mechanical preparation combined with a non-antiseptic irrigating solution was capable of reducing approximately 50% of bacteria in root canals, while NaOCl material eliminated approximately 80%of bacteria . A limitation of this study was lack of microbial culture to support the clinical outcome. The combined strategy should be designed to correlate the clinical outcome of canal irrigants with support of microbiological study. Clinical symptoms should be compared with the bacteriologic status of canals for further confirmation of results.


Within the limitations of the current study, it appears that NaOCl may perform better than H2O2 in terms of interappointment pain.


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