| Abstract|| |
Context: This study was carried out on the assumption that calcium hydroxide [Ca(OH) 2 ] dressing and irrigants may influence the obturation of lateral canals.
Aims: To evaluate the influence of 2.5% sodium hypochlorite (NaOCl), 2% chlorhexidine (CHX) gel and Ca(OH) 2 on the filling of artificial lateral canals.
Settings and Design: Ex vivo quantitative laboratory study.
Materials and Methods: Forty-two human mandibular premolars were selected. After cavity access, six lateral canals were performed, two in each root section, one mesial and one on the distal root surface. After preparation, the specimens were randomly divided into four groups: Group I: Under irrigation with 2% CHX and saline solution and with intracanal dressing Ca(OH) 2 paste; Group II: The same preparation as Group I, but without Ca(OH) 2 ; Group III: Under irrigation with 2.5% NaOCl without Ca(OH) 2 ; and Group IV: The same preparation as Group III, but with Ca(OH) 2 . Two teeth without intracanal dressing were used as negative controls. Lateral condensation technique was performed. Then, digital radiographic images were obtained.
Statistical Analysis Used: Data were analyzed using SPSS 17.0, submitted to Kappa (reliability between examiners) and Kruskal-Wallis test.
Results: No statistical difference was registered between Groups II and III in all root sections (P > 0.05), but it was observed between Groups I and IV (P < 0.05), except on the apical section (P > 0.05). In all sections, the Group I filled more artificial lateral canals than in Group IV.
Conclusions: The irrigants tested had no influence on the filling of artificial lateral canals. Nevertheless, intracanal dressing of Ca(OH) 2 influenced this filling.
Keywords: Calcium hydroxide, chlorhexidine, root canal obturation, sodium hypochlorite
|How to cite this article:|
Deonizio MD, Teixeira BD, Gabardo MC, Batista A, Kowalczuck A, Sydney GB. Influence of calcium hydroxide dressing and two irrigants on the filling of artificial lateral canals. Indian J Dent Res 2015;26:588-91
Calcium hydroxide [Ca(OH) 2 ] paste is advocated as the most important intracanal dressing in root canal therapy because of its biological and antimicrobial properties. ,, However, in vitro studies have reported the difficulty of Ca(OH) 2 removal before root canal filling. A considerable amount of Ca(OH) 2 remained attached to the root canal walls after instrumentation and irrigation. ,,, This condition interferes on the obturation of the root canal system. ,
|How to cite this URL:|
Deonizio MD, Teixeira BD, Gabardo MC, Batista A, Kowalczuck A, Sydney GB. Influence of calcium hydroxide dressing and two irrigants on the filling of artificial lateral canals. Indian J Dent Res [serial online] 2015 [cited 2019 May 19];26:588-91. Available from: http://www.ijdr.in/text.asp?2015/26/6/588/176921
The influence of root canal irrigants on filling artificial lateral canals was tested.  Sodium hypochlorite (NaOCl) and chlorhexidine (CHX) has been studied this purpose, , confirming that the irrigants play an important role, especially removing the debris and smear layer,  not affecting the obturation.  In addition, it is well established that ethylenediaminetetraacetic acid (EDTA) allows intracanal dressing to penetrate the dentinal tubules, and its action is important before filling the root canal, removing the deposits of Ca(OH) 2 from the entrance of the dentinal tubules and lateral canals. 
According to Ricucci and Siqueira  it must be stated that lateral canals and apical ramifications have been implicated with endodontic treatment failure when they are sufficiently large to harbor significant numbers of bacteria and to provide these bacteria with frank access to the periradicular tissues. Therefore, disinfection of lateral canals in cases of pulp necrosis should be important although difficult to be achieved. That is why attention to the irrigants is important, and care must be taken for Ca(OH) 2 removal from the system. A hermetic obturation is desirable since it is related to the success of endodontic treatment.
There is no information available regarding the effect of these two irrigants associated with or without Ca(OH) 2 on lateral canal fillings. Thus, the aim of this study was to evaluate the influence of both, Ca(OH) 2 dressing and the irrigants NaOCl and CHX, may influence the filling of artificial lateral canals.
| Materials and Methods|| |
Selection of specimens and coronal access
Based on data available in the literature, for establishing 10 teeth in each group, , forty-two human mandibular premolars, single-root, from the Teeth Bank of the Federal University of Paraná were selected after the Ethics Committee in Research approval (register no: 0098.09.000-09).
The specimens were radiographed in a mesiodistal direction to verify the presence of only one root canal. Teeth that presented more than one canal, mineralization, previous endodontic treatment or any other anatomical abnormality were discarded. Coronal access and glide path were performed with round and pyramidal diamond bur (1014 and 3205 - KG Sorensen, Barueri, SP, Brazil) and number 10 K-File (Dentsply-Maillefer, Baillagues, Switzerland), respectively.
Making the artificial sockets
Artificial sockets were made using an acrylic tube (Imepla, Pinhais, PR, Brazil) filled with vinyl polysiloxane impression material (Zetalabor-Zhermack, Badia Polesine, RO, Italy). The teeth were inserted into the tube to the cementoenamel junction [Figure 1].
Making the artificial lateral canals
This procedure was adapted from methodology introduced by Goldberg et al. 
For the manufacture of artificial lateral canals, a device was built using number 10 K-File (Dentsply-Maillefer, Baillagues, Switzerland) [Figure 2]. The file was inserted into the endodontic calibrator 0.20 mm diameter and sectioned. The handle was removed and fixed with self-curing resin (Reliance Dental Mfg Co-Worth, IL, USA) to a contra-angle handpiece (Microdont, Marabá, SP, Brazil).
Six lateral artificial canals were performed, two in each root section, one mesial and one on the distal root surface, with the device connected to a micromotor (20,000 rpm) at equidistant points. A long neck bur (Dentsply-Maillefer, Baillagues, Switzerland) was previously used as a guide for the device.
Root canal preparation
The teeth were randomly divided into four groups (n = 10). Root canal preparation was performed using a crown-down technique and master apical file was number 50 K-File (Dentsply-Maillefer, Baillagues, Switzerland). The working length was established 1 mm short from the apex. After root canal preparation the teeth were irrigated with 17% EDTA (Biodinâmica Química e Farmacêutica Ltda., Ibiporā, PR, Brazil) and dried with Capillary Tips (Ultradent Products Inc., South Jordan, UT, USA) and paper points ISO size 50 (Dentsply-Maillefer, Baillagues, Switzerland).
In Groups I and II 2% CHX gel (Essencial Pharma Lab., Itapetininga, SP, Brazil) was used as an irrigant and having a saline solution as an irrigant. In Groups III e IV 2.5% NaOCl was used. Teeth of Groups I and IV received an intracanal dressing of Ca(OH) 2 paste with distilled water, prepared by mixing two parts of lab grade Ca(OH) 2 and 1 ml saline solution to obtain a creamy consistency, and then inserted with a number 25 Lentulo drill (Dentsply-Maillefer, Baillagues, Switzerland), subtracting 2 mm from the working length. Two teeth irrigated with saline solution and without intracanal dressing were used as negative controls.
The cavities were sealed with Coltosol ® (Vigodent Coltene S.A. Indústria e Comércio, Rio de Janeiro, RJ, Brazil), and the specimens were maintained for 7 days at 37°C, with 100% humidity.
Completed, this time, the paste was removed from the root canal using number 45 and number 50 K-file (Dentsply-Maillefer, Baillagues, Switzerland) under irrigation of saline solution (Groups I and II) and 2.5% NaOCl (Groups III and IV). For final irrigation 10 ml of 17% EDTA was used and maintained for three minutes in all groups, followed by 10 ml of saline solution (Groups I and II) and 10 ml of 2.5% NaOCl (Groups III and IV).
The teeth were radiographed for assessing the filling quality after the Ca(OH) 2 intracanal placement. If this occurred, a new insertion of material was performed.
Root canal obturation
Next, all root canals were dried with Capillary Tips (Ultradent Products Inc., South Jordan, UT, USA) and paper points ISO size 50 (Dentsply-Maillefer, Baillagues, Switzerland). The master gutta-percha cone selected was the ISO size 50 (Dentsply-Maillefer, Baillagues, Switzerland). Root canal filling was performed with lateral condensation technique and AH-Plus ® endodontic sealer (DeTrey Dentsply GmbH, Konstanz, Germany) manipulated according to the manufacturer's instructions.
Register and analysis of the images
The images were taken by using a dental X-ray generator (70 Spectro X-Dabi Atlante, Ribeirāo Preto, Brazil), operating at 70 kVp and 8 mA, and Digital Kodak Dental Systems (RVG 5000, Eastman Kodak Company, Rochester, NY, USA). This system has a sensor with electrical and optical system and charge coupled device, producing an electrical signal which generates an image with resolution of 14 pl/mm real and true resolution of capturing images of 27.03 lp/mm. The target distance was 35 cm, and exposure time of 0.25 s.
Images were stored and then analyzed by three independent and calibrated evaluators, in three different time intervals. The scores followed were: 0 - no filling of lateral canals; 1 - fill up 1/3 of the artificial canals; 2 - fill half of the artificial canals; and 3 - complete filling of the artificial canals [Figure 3].
Data were tabulated and analyzed using the Statistical Package for the Social Sciences (SPSS), version 17.0 (SPSS Inc., Chicago, IL, USA). Kappa test was necessary to evaluate the intra- and inter-examiners' level of agreement. The Kruskal-Wallis test (P < 0.05) was done to verify the least significant difference between groups in the cervical, middle, and apical sections.
| Results|| |
The Kappa value intra- and inter-examiners was 0.89.
The results are expressed on [Table 1].
|Table 1: Mean values of filling lateral canals in each root section in each tested group |
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| Discussion|| |
The aim of this study was to evaluate the influence of Ca(OH) 2 dressing, NaOCl, and CHX on the filling of artificial lateral canals. These structures are related to the endodontic failure, allowing bacterial survival when empty. 
Ca(OH) 2 is widely used due to its properties and good clinical results. ,, However, its complete removal from the root canal space, prior filling, is not achieved using routine techniques, ,,, influencing the future obturation. 
In our study, observations were made into four experimental groups evaluating the influence of root canal irrigants (2.5% NaOCl and 2% CHX gel) and intracanal dressing with Ca(OH) 2 on the filling of artificial lateral canals. The artificial lateral canals are commonly used in the literature, specially indicated to the analyzes material penetration. ,
Our results showed remnants of Ca(OH) 2 , independent of the root section analyzed or the irrigant used, data consistent with previous results, confirming that this condition interferes on the obturation seal, hindering the penetration of the filling material in the root canal system.  de Sousa et al.  in an ex vivo analysis, demonstrated that the use of Ca(OH) 2 decreased the number and the length of sealed lateral canals.
As suggested by Goldberg et al.,  Ca(OH) 2 may block off the dentinal tubules and so, decrease dentinal permeability. Studies on apical leakage, that evaluated the effect of intracanal dressing, concluded that remnants of Ca(OH) 2 reduced leakage determining a better apical filling.  Contrary, results showed that the previous use of this medication increased apical leakage of gutta-percha root fillings. 
The analysis by root sections was performed to provide critical observation of the behavior of the Ca(OH) 2 and irrigants over the entire length of the root canal. There was no statistical difference between Groups II and III in all root sections, showing no interference of the irrigants. Other authors also indicated no influence of NaOCl and CHX on obturation.  It is necessary to highlight the use of 17% EDTA before root canal filling. We elected this solution because it is defended as an important auxiliary for removing the smear layer. 
A variation was verified regarding the filling in each section. Statistical difference was registered between groups where CHX and NaOCl, that received intracanal dressing (Groups I and IV), except on apical section. The apex is always a critical area. During smear layer removal, studies results point to the worst result with NaOCl followed by CHX.  In a comparison of these two groups, CHX gel permitted more lateral canals obturated than NaOCl, in all root sections. The lower filling of lateral canals, registered in Groups I and IV medicated with Ca(OH) 2 , is probably due to the difficulty of Ca(OH) 2 removal in this area as asserted by other authors. 
An advantaged pointed to CHX gel is the maintenance of almost all dentinal tubules open, because its viscosity keeps the debris in suspension, reducing smear layer formation.  As asserted by Pascon et al.,  NaOCl did not clean the canal walls well, but when associated with EDTA, is reached the best cleaning.
| Conclusion|| |
Based on the results here obtained, it can be concluded that the tested root canal irrigants had no influence on the filling of artificial lateral canals and that the intracanal dressing of Ca(OH) 2 influenced the outcomes.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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Prof. Marili Doro Andrade Deonizio
Department of Restorative Dentistry and Endodontics, Federal University of Paraná, Curitiba
Source of Support: None, Conflict of Interest: None
[Figure 1], [Figure 2], [Figure 3]