|Year : 2014 | Volume
| Issue : 5 | Page : 607-612
|Effect of four different intracanal medicaments on the apical seal of the root canal system: A dye extraction study
Monika Tandan1, Mithra N Hegde2, Priyadarshini Hegde2
1 Department of Conservative Dentistry and Endodontics Sudha Rustagi College of Dental Sciences and Research Centre, Kheri More, Faridabad, Haryana, India
2 Department of Conservative Dentistry and Endodontics, A. B. Shetty Memorial Institute of Dental Sciences, Deralkatte, Mangalore, Karnataka, India
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|Date of Submission||23-Mar-2013|
|Date of Decision||23-Nov-2013|
|Date of Acceptance||28-Aug-2014|
|Date of Web Publication||16-Dec-2014|
| Abstract|| |
Aim: The aim was to determine the effect of four different intracanal medicaments on the apical seal of the root canal system in vitro.
Methodology: Fifty freshly extracted intact human permanent maxillary central incisors were collected, stored and disinfected. The root canals were prepared to a master apical size of number 50 using step back technique. Depending upon the intracanal medicament used, the teeth were divided randomly into five groups of 10 teeth each including one control group and four experimental groups. Group A: No intracanal medicament. Group B: Calcium hydroxide powder mixed with distilled water. Group C: Calcium hydroxide gutta percha points (calcium hydroxide points). Group D: 1% chlorhexidine gel (hexigel). Group E: Chlorhexidine gutta percha points (Roeko Activ Points). The medication was left in canals for 14 days. Following removal of the intracanal medicament, all the groups were obturated with lateral compaction technique. The apical leakage was then evaluated using dye extraction method with the help of a spectrophotometer.
Results: Results were statistically analyzed using Kruskal-Wallis and Mann-Whitney U-test, which showed statistically significant difference among the five groups tested.
Conclusion: It can be concluded from this study that the control group showed least amount of leakage, whereas the 1% chlorhexidine gel group showed maximum amount of leakage. Apical leakage was observed with all the experimental groups with little variations in between them. Under the parameters of this study, it can be concluded that use of intracanal medicaments during endodontic treatment has a definite impact on the apical seal of the root canal system.
Keywords: Apical leakage, calcium hydroxide, chlorhexidine, intracanal medication
|How to cite this article:|
Tandan M, Hegde MN, Hegde P. Effect of four different intracanal medicaments on the apical seal of the root canal system: A dye extraction study
. Indian J Dent Res 2014;25:607-12
Elimination of microbial contamination from the root canal system is a pre-requisite to the successful outcome of root canal treatment. Chemo mechanical cleaning and shaping of the root canals greatly reduce the number of bacteria, but it has been shown that it is impossible to obtain complete disinfection in all cases. , Following instrumentation and irrigation, the use of interappointment medication has been widely advocated. Use of an effective intracanal medicament will assist in the disinfection of the root canal system. Such medication should be effective throughout its period of application, and penetrate the dentinal tubules, eliminating bacteria that maybe present, with little toxicity to the periradicular tissues. ,
|How to cite this URL:|
Tandan M, Hegde MN, Hegde P. Effect of four different intracanal medicaments on the apical seal of the root canal system: A dye extraction study
. Indian J Dent Res [serial online] 2014 [cited 2018 Dec 15];25:607-12. Available from: http://www.ijdr.in/text.asp?2014/25/5/607/147104
Calcium hydroxide has been recommended for use as an intracanal medicament based on its antibacterial, antiresorptive and tissue dissolving properties.  It has been used clinically to obtain microbial control, dissolve organic remnants, heal periapical inflammation, arrest inflammatory root resorption, stimulate hard tissue formation and serve as a temporary obturating material in between appointments.  The most common and effective type of calcium hydroxide is an aqueous suspension.  Despite its good antimicrobial effect, it exhibits poor handling properties, and its distribution throughout the canal is problematic.  Another challenge is its complete removal. Recently, developed endodontic points containing calcium hydroxide have been developed to address the handling and application of conventional calcium hydroxide preparations. 
The use of chlorhexidine as an intracanal medicament has been suggested either in the form of 2% gel or solution placed in a sustained release device or active points.  Chlorhexidine has strong antibacterial activity against a wide range of Gram-positive and Gram-negative as well as yeast, facultative anaerobes and aerobes. It is particularly effective against Enterococcus faecalis andida strains, which have been implicated in endodontic treatment failures and were resistant to treatment with calcium hydroxide.  Important characteristics of chlorhexidine are protein binding and substantivity, thereby, prolonging the period of antibacterial activity and also its low toxicity.  Chlorhexidine containing gutta-percha points have been introduced, allowing easy insertion into the root canals. 
An important factor in the success of root canal treatment is complete sealing of the entire canal space to prevent the percolation of microorganism and toxins to the periapical area.  The quality of the apical seal can be affected by many factors such as canal instrumentation, irrigation, intracanal medicament, type of root canal sealer, nature of filling material, method of canal obturation and degree of spreader penetration. 
There is a concern that at the time of root canal filling, the retention of intracanal medicament on the canal wall might affect the quality of the apical seal and influence the prognosis of the treatment.  Intracanal medicaments should be removed completely from the root canal system. However, none of the existing techniques are efficient in removing the entire material, leaving up to 45% of the root canal surface covered with remnants. Moreover, the residual intracanal medicament may interact with the root canal sealer and interfere with its sealing ability. 
Hence, the aim of the present study was to determine the effect of four different intracanal medicaments on the apical seal of the root canal system.
| Methodology|| |
Fifty freshly extracted human permanent, non-carious, maxillary central incisors with straight roots, single canals and mature apices were used in this study. The teeth with calcified canals, extra canals, curved canals, external or internal resorption or previous restorations were excluded. Their external surfaces were cleaned with curettes to remove any calculus or soft tissue debris. The teeth were collected and initially stored in a wide mouthed plastic jar containing 0.5% sodium hypochlorite (Vensons India Co.). They were disinfected by immersing the collected teeth in 5% sodium hypochlorite for at least h. The teeth were rinsed with tap water before use.
To facilitate instrumentation, the crown of each tooth was removed at cemento-enamel junction using diamond disc. To eliminate root length as a variable, only teeth with roots 12-15 mm long were used. The canal contents were grossly debrided with barbed broaches (Dentsply Maillefer Ballaigues, Switzerland) and irrigated with 2.5% sodium hypochlorite. The working length was determined by placing number 10 K file (Dentsply Co.) into the canal and advancing it until it was just seen at the apical foramen, after which 1 mm was subtracted from this and working length was recorded. The canals were prepared with stainless steel K files in sequential order beginning with number 15 to number 50 at the working length. Between each file use, the canals were irrigated with 1 ml of 2.5% sodium hypochlorite and saline using a 22 gauge needle alternatively. Patency was confirmed between files using a number 10 stainless steel K file. Following apical preparation, the canals were flared with number 55, number 60, number 70 and number 80 K files in step back fashion 2, 3, 4, and 5 mm short of working length respectively. Irrigation was done in the manner previously described. Further coronal enlargement was accomplished with a number 3 and number 4 Gates Glidden drill (Dentsply Co.).
The smear layer was removed using 3 ml of 17% ethylene diamine tetraacetic acid (EDTA) solution followed by 3 ml of 2.5% sodium hypochlorite. Final rinse was accomplished with 3 ml of physiologic saline. Upon completion of instrumentation, the canals were dried utilizing absorbent points. The teeth were then randomly divided into five groups of 10 teeth each comprising of one control group and four experimental groups. Four different intracanal medicaments viz. calcium hydroxide powder (Deepti Dental Products of India), calcium hydroxide active points (Coltene Whaledent), 1% chlorhexidine gel (Hexidine gel; ICPA Health Product Private limited) and Chlorhexidine points (Roeko Activ Points; Coltene Whaledent) were used in the experimental groups for 2 weeks.
In the control Group A, no medicament was placed but they were sealed coronally with intermediate restorative material (Dentsply Co.). In the experimental Group B, calcium hydroxide paste was made by mixing calcium hydroxide powder with distilled water at a powder liquid ratio of 1:1.25. The calcium hydroxide paste was placed in the canal with the use of lentulospiral (Dentsply Co.). In Group C, calcium hydroxide active point of master apical size (number 50) was placed using a tweezer. The excess of the active point was folded into the canal to facilitate its removal later on. In Group D, 1% chlorhexidine gel was placed in the canals using a capillary tip (Ultradent Co.). In Group E, chlorhexidine active points of master apical size (number 50) was placed using a tweezer. The access cavities of experimental teeth were sealed with 1 mm of cotton pellet and 1 mm layer of intermediate restorative material and were stored in isotonic saline for 14 days.
At the end of the experimental period, the intracanal medicaments were removed from the experimental groups. In experimental Groups B and D, the canals were irrigated copiously with 2.5% sodium hypochlorite and saline and number 50 size K file was used in the filing motion up to the working length to ensure complete removal of the intracanal medicaments. In Groups C and E, after removing the temporary restorative material the excess folded active point was pulled out of the canal using a tweezer. The canals were irrigated and instrumented with a number 50 size K file to ensure removal of any remaining material adhering to the canal wall. The canals were irrigated again with 3 ml of sodium hypochlorite and dried using absorbent points. Smear layer was removed using 17% EDTA in all the teeth. Both the experimental and control group were obturated with the gutta percha (0.02 taper; Dentsply Co.) using lateral compaction technique and AH Plus sealer (Dentsply Co.). After obturation, the excess gutta percha was removed with a heated instrument and the access cavity was sealed with type II Glass Ionomer Cement (GC Company). The apical seal was evaluated for all the teeth including control and experimental groups using dye extraction method.
Dye extraction method
The teeth were covered with two layers of nail varnish except for the last apical 2 mm. The teeth were submerged in glass vials for 24 h at 37°C in neutral buffered 2% methylene blue solution, under normal atmospheric pressure.
The teeth were rinsed under tap water for 30 min, and the varnish was removed with polishing disks mounted on a handpiece. The teeth were stored in a hermetic sealed vial containing 600 μl of concentrated nitric acid for three days. The vials were then centrifuged at 10,000 rpm for 10 min. A volume of 200 μl of supernatant was taken from each vial and the absorbance was determined at 550 nm using a spectrophotometer (Statfax -2100; Awareness Technology).
The data obtained was statistically analyzed using Mann-Whitney U-Test and Kruskal-Wallis test. The significance value was set at P ≤ 0.05.
| Results|| |
The absorbance value for each sample was recorded and was tabulated [Figure 1]. The mean for all the groups was calculated along with a standard deviation [Figure 2] and subjected to statistical analysis using Kruskal-Wallis test followed by intergroup comparison using Mann-Whitney U-test. The mean absorbance obtained was in the following order [Table 1]; A < C < E < B < D. The results obtained showed that control group had the least amount of leakage, whereas chlorhexidine gel when used as an intracanal medicament exhibited the highest amount of apical leakage. The medicated gutta percha points whether calcium hydroxide based, or chlorhexidine based were found to be better than calcium hydroxide paste in terms of apical leakage. Furthermore, the data were subjected to Mann-Whitney U-test to determine the intergroup comparison. The significance values obtained were mixed, which are depicted in [Table 2].
|Figure 2: Comparison of mean absorbance and standard deviation indicating apical leakage of five groups determined spectrophotometrically following intracanal medicament use at 550 nm|
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| Discussion|| |
Intracanal medicaments are routinely used in root canal treatment, however they should only be used for root canal disinfection as part of controlling sepsis in infected root canals and their role is secondary to cleaning and shaping of the root canal.  For an intracanal medication to be suitable for clinical application, it must be easy to introduce into the root canal for proper contact with the tissues and easy to remove to ensure the effective seal of the root filling. The intracanal medication performs the antibacterial action by being in contact with the tissues and by diffusing through them.  An important consideration in endodontics is the ultimate seal of the root canals in order to prevent possible microleakage that may be the cause of future
failure of the root filling. Leakage of the root canal system is an important consideration when placing an intracanal medication. 
Calcium hydroxide has been used as an intracanal medicament in different clinical situations. It has been shown to be effective in eliminating bacteria from the root canal space. Calcium hydroxide maintains its antibacterial effect over a long period of time, due to slow release of hydroxyl ions.  Calcium hydroxide is available in several formulations due to the number of vehicles that can be used along with it. The most commonly used calcium hydroxide is calcium hydroxide paste mixed with distilled water. The problem associated with it is its incomplete removal resulting in calcium hydroxide remnants on the canal walls. 
Calcium hydroxide points are relatively a recent development and are designed to release calcium hydroxide from a gutta percha matrix. The constituents include 58% calcium hydroxide and 42% gutta percha. It is recommended that the point should be inserted into the canal to the working length and should be placed passively such that moist air is able to circulate freely. The points are claimed to leave no residual material and can be removed easily with tweezers or hedstrom file. 
Chlorhexidine gluconate is a broad spectrum antibacterial agent. It acts by adsorbing onto the cell wall of the microorganism and causing leakage of intracellular components. Chlorhexidine's ability to adsorb to anionic substrates and to be slowly released from the sites (substantivity) provides a long standing antibacterial effect.  Chlorhexidine is significantly more effective than calcium hydroxide in eliminating E. faecalis and Candida albicans. Its use in gel form allows a longstanding action.  A new formulation of chlorhexidine impregnated gutta percha points has recently been marketed. Active points contain gutta percha embedded with 5% chlorhexidine diacetate. This innovation allows ease of introduction and retrieval from the root canal. 
In this study, extracted human teeth were used to improve reliability by simulating the clinical situation. Maxillary central incisors with straight roots, mature apices and single patent root canals were selected to minimize anatomical variation and allow standardization. Decoronization was done in order to facilitate instrumentation and also to allow standardization. In the present study, the smear layer was removed to facilitate penetration of the intracanal medicaments. Nerwich et al. demonstrated in their study that the hydroxyl ions derived from a calcium hydroxide intracanal dressing diffuse in a matter of hours into the root dentin but require 2-3 weeks to reach peak levels. Intracanal medicament was given for fourteen days as this is the period commonly used between appointments (especially calcium hydroxide).  To minimize any apical leakage due to the possible interaction between calcium hydroxide and eugenol, resin based AH Plus sealer was used in this study.
Leakage at the apex occurs between the root canal wall and the sealer, between the sealer and the gutta percha, or within the sealer itself. In the present study, all the specimens were coated with the nail varnish on their root surface to exclude any possible leakage through the dentin surface to leave only apical pathways.  The roots were placed in methylene blue dye after 24 h to ensure setting of the AH Plus root canal sealer as per manufacturer's recommendations.
The samples were left in methylene blue dye for 24 h. Before immersing the samples in the concentrated nitric acid for the dye extraction technique as described by Zakariasen et al.,  the varnish was scraped off the roots in order to facilitate the dissolution and remove any contamination of the methylene blue dye on the nail varnish. Decalcification was carried out by placing the samples in concentrated nitric acid for three days. After 3 days, the extracted solution was centrifuged at 10,000 rpm for 10 min to separate the gutta percha debris. Subsequently, the supernatant was taken and the spectrophotometric reading was recorded and from these readings the actual volume of dye can be calculated. This method provides for a direct quantitative measurement of the material leaking into the radicular space. 
Results were statistically analyzed by Kruskal-Wallis test and for intergroup comparison Mann-Whitney U-test was carried out. Results revealed that the control group exhibited the least amount of leakage. However, there were no significant differences between the control group and the calcium hydroxide point group. It may be explained on the fact that calcium hydroxide points were removed in one piece, and there was no or minimal residue left behind which had no adverse effect on the apical seal.  There was statistical significant difference between the control group and both the 1% chlorhexidine gel and chlorhexidine medicated gutta percha points group. This could be due to the property of chlorhexidine that gets adsorbed onto the root surface (substantivity) and moreover, there could be some interaction between cationic biguanide and the resin based sealer used in the study.  Statistically significant differences were observed between the control group and the calcium hydroxide powder group. This can be attributed to the calcium hydroxide remnants adhering to the canal wall which may interfere physically with the sealing ability of the sealer. 
In the intergroup comparison, there were no statistically significant difference between the calcium hydroxide point and the calcium hydroxide powder group. Small difference associated with the two different formulations of calcium hydroxide may be because of the vehicle associated and the remnants left behind in the canal following their removal.  However, when comparing chlorhexidine points with 1% chlorhexidine gel, significant differences were observed. This may be explained on the fact that the gels containing chlorhexidine are difficult to remove completely from the canal space. , Nonetheless, comparison of calcium hydroxide and chlorhexidine impregnated gutta percha points showed no significant differences. This is due to easy retrievability of the medicated points. , When calcium hydroxide powder group was compared to the 1% chlorhexidine gel, no significant differences were found between the two groups which could be attributed to the difficulty in removing both the medicaments. ,
Porkaew et al. have studied apical leakage in teeth filled by lateral condensation technique following medication with calcium hydroxide. They observed significantly less leakage in the experimental groups treated with calcium hydroxide than in the control groups.  Similar results were observed by Holland et al.  Holland et al.  Kontakiotis et al.  Caliskan et al.  However, these studies also noted that when calcium hydroxide dressing was retained in the canal, apical leakage increased with time. Recently, Wu et al. has described the possibility of false results occurring with previous dye leakage studies using methylene blue dye, because it may lose its color in contact with calcium hydroxide. The decolorizing effect of calcium hydroxide is related to its high alkalinity, and this varies according to its form that is paste, cone or sealer. 
In contrast, others have observed variations in apical sealing ability and attributed them to remaining calcium hydroxide. Such conflicting results suggest that calcium hydroxide may react with root canal filling materials leading to variations in sealing ability.  The overall significance of the present study lies in the observation that neither material prevented apical leakage. This fact makes the debridement and sterilization phases extremely important. 
The dye extraction technique presents a drawback that should have been taken into account. The apical 2 mm of the apex exposed to dye penetration was not covered with varnish, permitting dye to penetrate into apical dentin that was dyed blue even after washing the roots. On the contrary, the dye extraction technique required only 3 days because the absorbance of all the teeth could be recorded at the same time. The dye extraction or dissolution technique is promising and rapid.  In this study, only the amount of dye absorbed is measured whereas the depth of penetration is not taken into account. The dye might have penetrated into the anatomical variations such as apical deltas, lateral canals, accessory canals and would have resulted in the higher amount of leakage observed giving higher readings.
In the light of the present study, additional experimentation is needed to analyze the exact cause of the breakdown of the apical seal and to devise a method for complete removal of intracanal medicament in order to prevent apical microleakage.
| Conclusion|| |
In the present study spectrophotometric evaluation was done to quantitatively analyze the extent of dye leakage using methylene blue dye for evaluation of apical seal following the use of four different intracanal medicaments.
The following conclusions were drawn:
- All the groups exhibited apical leakage irrespective of the fact that whether medicament was placed or not and also the type of intracanal medicament
- The control group without any intracanal medication exhibited the least amount of leakage, that was statistically significant from the experimental groups
- There were no significant differences between the calcium hydroxide and the chlorhexidine medicated gutta percha points groups and the calcium hydroxide powder, but they differed significantly from 1% chlorhexidine gel group
- 903; The 1% chlorhexidine gel group showed the maximum amount of leakage that was statistically insignificant when compared to the calcium hydroxide powder group.
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Department of Conservative Dentistry and Endodontics Sudha Rustagi College of Dental Sciences and Research Centre, Kheri More, Faridabad, Haryana
Source of Support: None, Conflict of Interest: None
[Figure 1], [Figure 2]
[Table 1], [Table 2]
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