| Abstract|| |
Aim: To evaluate the effect of method of calcium hydroxide intracanal dressing removal, on sealing ability of Gutta Flow and Activ GP.
Materials and Methods: Seventy extracted mandibular premolars were sectioned at CEJ and canals were prepared with profile 4% rotary file till #40. Canals were filled with calcium hydroxide, coronally sealed with Cavit G and stored at 37°C. After 7 days, samples were divided on the basis of calcium hydroxide removal method (Master apical file, Navi Tip FX, and F File) and obturating material (Activ GP and Gutta Flow). Three coats of nail polish were applied except 2 mm around apical foramen and samples were immersed in India ink dye, sectioned, and observed under stereomicroscope for microleakage. Results: The results were statistically analyzed with one way ANOVA-F with Tukey HSD test with the null hypothesis set as 5%.
Conclusions: The seal of the canal system was adversely impacted by residual calcium hydroxide when Activ GP and Gutta Flow were used as obturating material and the sealing ability of Activ GP and Gutta Flow was better when MAF was used for removal of calcium hydroxide than F file or Navi tip FX.
Keywords: Activ GP; calcium hydroxide; F file; Gutta Flow; Navi tip Fx; sealing ability
|How to cite this article:|
Nikhil V, Singh V, Singh S. Relationship between sealing ability of Activ GP and Gutta Flow and methods of calcium hydroxide removal. J Conserv Dent 2012;15:41-5
|How to cite this URL:|
Nikhil V, Singh V, Singh S. Relationship between sealing ability of Activ GP and Gutta Flow and methods of calcium hydroxide removal. J Conserv Dent [serial online] 2012 [cited 2020 May 30];15:41-5. Available from: http://www.jcd.org.in/text.asp?2012/15/1/41/92605
| Introduction|| |
Bacteria and their products play an essential role in pathogenesis of pulpo-periapical diseases.  A long-standing endodontic infection allows bacteria to propagate to the entire root canal system, including ramifications, isthmuses, apical deltas, and dentinal tubules. In these locations, bacteria may remain viable even after complete chemo-mechanical preparation of the root canal and may multiply in the period between treatments. Various intracanal medicaments have been advocated to prevent this occurrence, for example, phenols, iodine, potassium iodide, antibiotic paste, calcium hydroxide, propolis,  etc. Among these, calcium hydroxide (Ca(OH) 2 ) is most indicated and frequently used in clinical practice. The clinical success of this material is mainly attributed to its alkaline pH and depends on its ability to rapidly disassociate into hydroxyl ions and calcium ions. Tronsted et al.  demonstrated the diffusion of calcium ions through the dentin to the external surface. Ca(OH) 2 is advocated as an interappointment endodontic therapeutic dressing because of its antibacterial effect on most of the microorganisms identified in the root canal system.  Sjogren et al. found that Ca(OH) 2 dressing for 7 days efficiently eliminated bacteria that survive root canal instrumentation. Calt and Serper  reported that when Ca(OH) 2 was incompletely removed from root canal, sealer did not penetrate into the dentinal tubules. Therefore, its complete removal is necessary for the success of the root canal therapy. The removal of Ca(OH) 2 has been investigated using various products and techniques such as irrigants (Citric acid, EDTA NaOCl and distilled water), use of Master Apical File (MAF) along with these irrigants,  use of Navi tip FX (Ultradent Products Inc, South Jordan, UT.) and use of F File (Plasticendo).
A new silicone based sealer Gutta Flow (Coltene Whaledent, Langenau, Germany), has been introduced as alternative root filling material. Gutta flow is the cold fluid obturation system, which combines sealer and Gutta Percha (GP) in single material. It consists of a polydimethylsiloxane matrix that is highly filled with very finely grounded GP. Gutta Flow has very promising properties because of its insolubility, biocompatibility, postsetting expansion, great fluidity, and providing thin film of sealer.  The Activ GP precision obturation system (Brasseler USA, Savannah, GA) is a new glass-ionomer (GI)-based obturation system. As inadequate bonding between GP and GI is a drawback of the GI-based sealer, thus, to enhance the GP-GI bonding, Activ GP has 2 μm coating of GI particle in its surface; these particles are also incorporated into the body of the cone. Activ GP gives the advantage of monobloc obturation (true single cone technique), and glass ionomer cements ( biocompatibility, adhesion, fluoride release and antimicrobial activity). 
Thus, the aim of this study was to evaluate the effect of various methods (MAF, Navi Tip FX, and F File) used for removal of Ca(OH) 2 intracanal dressing from canals, on sealing ability of these new obturating materials, that is, Gutta Flow and Activ GP.
| Materials and Methods|| |
Seventy noncarious, human, extracted mandibular premolars were radiographed in proximal view to exclude any teeth with more than one canal, selected and sterilized. The teeth were sectioned at CEJ using a Diamond disc and water spray. The patency of the canal was determined and ensured by passing a #10 K file 2 mm out of the apical foramen and working length for each root was established 0.5 mm short of the apex. Glide path was created for the use of the rotary file with 20 K-file. Root canals were prepared till #40 with 4% tapered profile with alternate use of 5% NaOCl and 10% citric acid and final irrigation was done with distilled water. Among 60 samples, the root canals were dried with #40 sterile absorbent points and were filled with Ca(OH) 2 and chlorhexidine paste using lentulospiral. Coronal seal was obtained with Cavit G and the samples were stored for 7 days at 37°C at 100% relative humidity. Then these samples were divided into three experimental groups of 20 samples each on the basis of method of removal of Ca(OH) 2 .
- GR 1 -Using MAF and irrigation with 5% NaOCl and 10% citric acid and final irrigation with distilled water.
- GR 2 -Using Navi tip FX and irrigation with 5% NaOCl and 10% citric acid and final irrigation with distilled water.
- GR 3 -Using F file and irrigation with 5% NaOCl and 10% citric acid and final irrigation with distilled water.
Each group was further divided into two subgroups (a and b), on the basis of obturating material Activ GP (1a, 2a, and 3a) and Gutta Flow (1b, 2b, and 3b), respectively. Activ GP and Gutta Flow were mixed according to manufacturer's directions, GP cones were coated with appropriate sealer and canals were obturated. Extra GP were sheared off at the coronal end with heated ball burinsher. Remaining ten samples (group-4) were used as the control group in which no calcium hydroxide dressing was given and among these five samples were obturated with Activ GP (GR 4a) and remaining five were obturated with Gutta Flow (GR 4b).
All samples were sealed with Cavit G, 3 coats of nail polish was applied except 2 mm around apical foramen and immersed in India ink dye for 5 days. For the microleakage observation these samples were sectioned bucco-lingually with chisel-mallet and then observed under the stereomicroscope.
| Results|| |
The mean values and the standard deviations for microleakage were calculated for each group and analyzed using the one-way ANOVA-F test as shown in [Table 1] for all the groups.
|Table 1: Mean microleakage in mm and standard deviation of various groups.|
Click here to view
The mean value of microleakage in mm for control groups was lower (1.48) than the mean values of experimental groups. Among the experimental groups, maximum microleakage was observed with gr-2, followed by gr-3 and gr-1.
Among all the experimental groups, the maximum microleakage value was recorded for Group 2a where the Navitip Fx was used for removal of calcium hydroxide and obturation was done with Activ GP with the mean value of 2.87 and standard deviation of 0.5172. On the other hand, the group 1b displayed the minimum microleakage value where the MAF was used for the removal of calcium hydroxide and obturation was done with the Gutta Flow the mean value of 1.61 and standard deviation of 0.890 348.
Intergroup comparison was conducted by using the multiple comparison tests (Tukey's HSD test) which revealed statistical significant differences among the groups [Table 2].
The Tukey's highly significant difference value was 0.6124 for groups 1a, 2a, 3a, and 4a, 0.7318 for 1b, 2b, 3b, and 4b while 0.998 for 1, 2, 3, and 4.
All the groups exhibited highly statistically significant difference except 1a-3a and 2a-3a, 1b-4b, 2b-3b, and 2-3, where values were found less than the Tukey's HSD value respectively but when student t-test was applied the P values were significant for group 1a-3a (P=0.004) and 1b-4b (P=0.0009). When student t-test was applied for various a groups (1a+2a+3a) and b groups (1b+2b+3b) of experimental samples the value was statistically insignificant (P=0.315 272).
| Discussion|| |
Studies have demonstrated that bacteria may be viable in the root canal even after vigorous mechanical instrumentation and use of irrigants with the antimicrobial activity, which may lead to the persistent or secondary intraradicular infection and therefore to treatment failure. Thus, the use of an intracanal medication with antimicrobial activity between therapy sessions has been recommended to eliminate possible persistent microorganism particularly in cases of pulpal necrosis with periradicular bone loss. Ca(OH) 2 has antimicrobial activity as it maintains the high concentration of OH ion that inactivate the bacterial enzymes of cytoplasmic membrane, influence chemical transport and alter the availability of nutrients thus, causing toxic effect on the bacterial cell. It acts by damaging bacterial DNA and protein denaturation. ,
In vitro studies have shown that remnants of Ca(OH) 2 can hinder the penetration of sealer into dentinal tubules which ultimately affects the adhesion of root canal sealer to the dentin that markedly increase the apical leakage of root canal treated teeth.  In addition, potential interaction of Ca(OH) 2 with zinc oxide eugenol sealers makes them brittle and granular.  Thus, complete removal of Ca(OH) 2 from root canal before obturation becomes mandatory.  Ca(OH) 2 removal before final obturation is routinely accomplished either by irrigation with NaOCl or saline or instrumentation in a reaming motion. Margeloas et al.  has shown that using 10% citric acid and NaOCl in combination with instrumentation by mechanical means improve the removal efficiency. Wiseman et al. used sonic and passive ultrasonic irrigation for Ca(OH) 2 removal and concluded that complete removal of Ca(OH) 2 cannot be accomplished with both the methods; however, the combination of rotary instrumentation and passive ultrasonic activation results in significantly lower amounts of Ca(OH) 2 remnants in the canal compared with sonic irrigation. Other methods include the use of Navi tip FX (Ultra dent) along with irrigants NaOCl and 10% citric acid and followed by distilled water.  and CanalBrush and ultrasonic agitation of NaOCl.  Ca(OH) 2 can also be removed with use of F file.
Machado-Silveiro LF,  in their study on decalcification of root canal dentine by citric acid, EDTA and sodium citrate, concluded that citric acid at 10% was the most effective decalcifying agent, followed by 1% citric acid, 17% EDTA, and 10% sodium citrate. Similarly Zehnder  stated that citric acid appears to be slightly more potent at similar concentration than EDTA when used as demineralizing agents in the root canal. Nandini et al.  retrieved the calcium hydroxide intracanal medicament after 7 days using 17% EDTA or 10% citric acid in combination with ultrasonic agitation. They performed the volume analysis using spiral-computed tomography. Their result showed that 10% citric acid showed better removal efficiency than 17% EDTA for Metapex. Farhad AR  came out with an opinion that when a resin-based sealer is used for the obturation of the root canal system, it is better to use a citric acid irrigant instead of EDTA to remove the smear layer and to improve the apical seal. All these findings motivated us to use 10% citric acid instead of 17% EDTA that is most commonly used demineralizing agent in this study.
India ink was used in this study because methylene blue which is most commonly used in the dye penetration test is not compatible with Ca(OH) 2 . Optical density of the methylene blue solution was decreased by 73% with Ca(OH) 2 which may result in unreliable results. 
In this study, when the mean microleakage value of control group (1.48) was compared with experimental groups (3.425, 5.515, and 4.875) the value was statistically highly significant [Table 2]. That supports the view that calcium hydroxide when used as intracanal dressing decreases the sealing ability of Activ GP and Gutta Flow and is in accordance with the view of Kim SK.  da Silva et al.  and Balvedi et al. used different types of vehicles for mixing Ca(OH) 2 and found that when various methods were used to remove Ca(OH) 2 , the dentine surface remained equally covered by Ca(OH) 2 , regardless of the vehicle used. Residual Ca(OH) 2 may block opening of lateral canals and dentinal tubules thus reducing the penetration of the sealer into them.  In general, the dentinal tubules are considered to have a diameter of 2 to 5 μm.  Several studies reported that Ca(OH) 2 particles vary from 0.5 to 20 μm. Dentin is substrate whereas Ca(OH) 2 is a material. The size of dentinal tubule correlates with the size of Ca(OH) 2 particles. According to Komabayashi et al.  the cumulative percentage of particles of Ca(OH) 2 between 0.5 and 2 μm was 63%. Therefore, in theory, the geometry of these small particles makes it possible for Ca(OH) 2 to enter the open dentinal tubules.
When the mean values for microleakage for Group 1, Group 2, and Group 3 were compared, the Tukey's HSD test showed highly significant difference between group 1-2 (1.935) and group 1-3 (1.59) but not between group 2-3 (0.345). This means that microleakage was significantly less when MAF was used for removing Ca(OH) 2 than when Navi tip FX and F file were used for removal. According to Kenee et al.  while irrigant alone could not penetrate well into apical third, mechanical means of removal showed significantly better result, possibly due to their ability to reach the apical third of the canal. Kuga et al.  stated close proximity of the instrument to the walls and apex is an important factor in cleaning the canal. It is obvious that profile instrument which was MAF for the prepared canal entered apical third directly, and to full extent as the canal shape matched the file shape and the instrument stiffness had also helped accessibility to the apical region, in the presence of Ca(OH) 2 . Navi tip FX had equidiameter bristles throughout the length except at the apex which was bristle free. This made Navi tip FX different in shape than prepared canal causing difficulty in accessing the apical part of the canal. This would have led for improper removal of Ca(OH) 2 by Navi tip FX that ultimately affected the sealing ability of sealer. The endodontic polymer-based rotary finishing file which had a unique design with diamond abrasive embedded in non toxic polymer, enabled the file to agitate NaOCl, removed remaining dentinal wall debris without enlarging the canal. Although these instruments had 0.04 taper thus it could reach the apical part of preparation but as this instrument comes only in 20 no. file size, its size did not correspond to the preparation size. The F file might had reached the apical terminus of the preparation but would had not contacted well with root canal walls that may be the reason that microleakage when F file was used to remove the Ca(OH) 2 was less than when Navi tip FX was used, but was more than when MAF was used for the removal of Ca(OH) 2 , providing more clean surface for sealers.
The mean values for Group 1a, Group 2a, and Group 3a were 1.815, 2.87, 2.37, respectively [Table 1]. When these groups were compared, a statistical value was significant for Group 1a: Group 2a and Group 2a: Group 3a, but the results were insignificant for Group 1a: Group 3a [Table 2]. When comparisons were drawn between Group 1b, Group 2b and Group 3b the mean values were 1.61, 2.645 and 2.505 mm, respectively [Table 1]. Statistically the results were significant for Group 1b: Group 2b and for Group 1b: Group 3b, But the results were insignificant for Group 2b: Group 3b [Table 2]. The explanation may be that due to better removal of Ca(OH) 2 by MAF or F file there was better bonding of Activ GP and Gutta Flow in comparison when Navi tip FX was used for removal of Ca(OH) 2 dressing. As we know Activ GP is GIC based sealer and for the adequate bonding with root canal wall or to form tertiary monobloc which is characteristic feature of the Activ GP  all the root canal surface should be cleaned and smear layer should be removed. Similarly the Gutta flow contains finely ground powder plus the silicone based matrix and for Gutta Flow the root canal must be free of any sort of residue either solid or liquid which may prevent the Gutta Flow from curing, thus thorough cleaning of the root canal is again necessary before the obturation. That is why as MAF was best in providing clean canal after removal of Ca(OH) 2 dressing followed by F file and Navi Tip FX the microleakage estimated was also less for MAF samples than F file and Navi Tip FX. Friction created between the brush bristles and the canal irregularities might result in dislodgement of the radiolucent bristles in the canal that are not easily recognized by clinician even with use of surgical microscope. This might further affect the sealing of root canal. 
When in the experimental group mean values of microleakage of samples with Gutta flow and Active GP was compared student t-test showed the insignificant value (P=0.315272), that means if the methods of removal of Ca(OH) 2 remains same there is no statistically difference in microleakage values between Gutta flow and Active GP.
| Conclusion|| |
Within limitations of this laboratory study, the findings showed that the seal of the canal system was adversely impacted by residual Ca(OH) 2 when Activ GP and Gutta Flow were used as obturating material and the removal of Ca(OH) 2 from root canal was better when MAF was used as compared to that by F file or Navi Tip FX. Before extrapolating the results of the present study to be deemed clinically significant, studies are needed to be undertaken with larger sample size. More over as Activ GP and Gutta flow are relatively new materials, the effect of intracanal dressing of Ca(OH) 2 on sealing ability of these materials should also be tested in vivo models.
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Flat # 1, R Block, Subharti University, Subharti Puram, NH-58, Delhi, Haridwar, Meerut Bypass, Meerut, Uttar Pradesh
Source of Support: None, Conflict of Interest: None
[Table 1], [Table 2]