|Year : 2014 | Volume
| Issue : 1 | Page : 1-5
An in vitro comparative analysis of glucose leakage for three contemporary single-cone obturation systems
Mohamed Abdel Aziz El-Sayed1, Ahmed Abdel Aziz Taleb2, Mohamed Sulaiman Mubarak Balbahaith2
1 Department of Conservative Dentistry Faculty of Dentistry, Ajman University, United Arab Emirates; Department of Conservative Dentistry, Mansoura University, Egypt
2 Department of Conservative Dentistry Faculty of Dentistry, Ajman University, United Arab Emirates
|Date of Web Publication||20-Mar-2014|
Mohamed Abdel Aziz El-Sayed
Faculty of Dentistry, Mansoura University, Egypt
Source of Support: None, Conflict of Interest: None
Aim: To compare the sealing ability of three innovative single-cone obturation systems. Materials and Methods: The roots of 90 maxillary incisors were prepared with ProTaper rotary files until reaching to size F4. The roots were divided into four experimental ( n = 20 each) and two control groups ( n = 5 each). The experimental groups were filled as follows: Group 1, Cold lateral condensation using gutta-percha/AH Plus Jet; Group 2, Single-cone ProTaper gutta-percha/Guttaflow2; Group 3, Single-cone Propoint PT/Smartpaste; and Group 4, Single-cone Propoint PT/Smartpastebio. The sealing ability of root canal fillings was tested at different time intervals using the glucose leakage model. Glucose leakage values were measured (mg/dL) by a spectrophotometer and statistically analyzed. Results: All experimental groups presented significantly different glucose leakage at all experimental periods ( P < 0.05). There was a progressive increase in the glucose leakage during the experimental periods in all groups. During experimental periods, Groups 4 showed the lowest significant cumulative glucose leakage values ( P < 0.05). Conclusion: Single-cone obturation technique using Propoint PT and Smartpastebio sealer provided the superior sealing ability and may be considered an alternative to the lateral condensation technique.
Keywords: Glucose leakage model, guttaflow2, microleakage, root canal filling, smartseal
|How to cite this article:|
El-Sayed MA, Taleb AA, Balbahaith MM. An in vitro comparative analysis of glucose leakage for three contemporary single-cone obturation systems. J Res Dent 2014;2:1-5
|How to cite this URL:|
El-Sayed MA, Taleb AA, Balbahaith MM. An in vitro comparative analysis of glucose leakage for three contemporary single-cone obturation systems. J Res Dent [serial online] 2014 [cited 2020 Jun 4];2:1-5. Available from: http://www.jresdent.org/text.asp?2014/2/1/1/129002
| Introduction|| |
The purpose of the root canal obturation is to eliminate any space that would allow penetration of the fluids between the filling material and the canal wall. 
Today, there is an increasing demand for prompt and efficient obturation technique which improves practice and causes less stress for the patients and clinicians. With the widespread use of rotary NiTi instruments and matched-taper gutta-percha cones, the single-cone obturation technique has become popular especially after developing new root canal filling systems.
GuttaFlow2 (Coltene/Whaledent, Altstätten, Switzerland) is a cold-ﬂowable, self-curing material and composed of gutta-percha powder, polydimethylsiloxane, and nanosilver particles. It has a good adaptability because of its high flowability and setting expansion. 
Smartseal (Smartseal, Stamford, UK) is a new filling system comprising a single-cone filling point (Propoint) and a paste type epoxy-amine resin based sealer (Smartpaste) or premixed biocermaic sealer (Smartpastebio). The Propoint cone consists of a radiopaque central polymeric core coated with a hydrophilic polymer sheath.  An active polymer powder is added during mixing of smartpaste that undergoes hydrophilic swelling.  Smartpastebio uses moisture in dentinal tubules to initiate and complete its setting reaction. Additionally, it has excellent physical properties such as high flow rate, setting expansion, high sealing ability, and antimicrobial activity. ,
A variety of laboratory-based experimental methods are used to detect and measure leakage along root fillings. These methods include dye penetration, spectrometry of radioisotopes, fluorometric and electrometric methods, bacterial penetration, and fluid transport model.  Xu et al., discussed a new model that measures the leakage of glucose molecules quantitatively by using a spectrophotometer.
The aim of the present study was to evaluate the microleakage along three single-cone root canal fillings in comparing with cold gutta-percha lateral compaction technique using glucose leakage model at different time intervals. The following combinations were tested: ProTaper gutta-percha/GuttaFlow 2, Propoint PT/Smartpaste, and Propoint PT/Smartpastebio.
| Materials and Methods|| |
Preparation of samples
A total of 90 freshly extracted human maxillary incisors with sound roots were used. Teeth with their roots showing open apices and cracks were excluded. Radiographically, the selected teeth should have nearly similar root canal anatomy and dimensions. The crowns were cut so that the length of roots was standardized at 15 mm. The size of the initial file for all selected roots should not exceed size 30 K-file. All canals were instrumented by Pro Taper NiTi rotary files to size F4 (DentsplyMaillefer) and irrigated with 3% sodium hypochlorite (NaOCl) solution using Vibringe® Ultrasonic Dental Irrigation Syringe (Medgedget) and a 27-gauge Max-i-Probe needle (DentsplyMaillefer). Eventually, all canals were rinsed with 17% ethylenediaminetetraacetic acid (EDTA) solution, followed by distilled water as a final irrigation to remove any traces of NaOCl.
Prepared samples were divided into four experimental groups of 20 samples each and two control groups of five samples each. Samples in the negative control group did not receive root canal fillings, while in the positive control group they were obturated only with a single-cone ProTaper gutta-percha size F4 (DentsplyMaillefer).
The experimental groups were filled as follows: Group 1, Cold lateral condensation using gutta-percha size 40 and 0.02 taper/AH Plus Jet; Group 2, Single-cone ProTaper gutta-percha size F4/Guttaflow2; Group 3, Single-cone Propoint PT size F4/Smartpaste; and Group 4, Single-cone Propoint PT size F4/Smartpastebio.
In Group 1, AH Plus Jet (DentsplyDetrey, Konztant, Germany) was directly injected to fill the apical third of the canals through the attached intraoral tip. The tip of a prefitted master gutta-percha cone of size 40 and 0.02 taper was then coated with a thin layer of sealer and introduced apically into the canal to the full working length. Lateral condensation was achieved using size-25/0.02 standardized gutta-percha cones and size C finger spreader (D1 diameter 0.3 mm, 0.04 taper) (DentsplyMaillefer). Excess gutta-percha cones were subsequently seared off with a hot hand plugger (0.5 mm diameter, DentsplyMaillefer) and vertically compacted using the same size hand plugger and the excess sealer was wiped using a cotton pellet wetted with alcohol.
In Group 2, the tip of the prefitted master gutta-percha cone size F4 was lightly coated with GuttaFlow 2 sealer and slowly inserted inside the canal using up and down pumping motion until reaching to the full working length. Excess gutta-percha was seared to the level of the canal orifice using a hot instrument.
In Group 3, a suitable amount of Smartpaste sealer (Smartseal, Stamford, UK) was dispensed from the dual syringe into mixing tray provided in the Smartseal kit. One scoop of active powder supplied with the kit was added and stirred well with the sealer using a plastic spatula until a homogeneous mass was obtained. The mixed sealer was then introduced into the canal using a lentulo spiral rotated at 300 rpm and 3 mm away from the apex. The tip of Propoint PT size F4 (Smartseal, Stamford, UK) was dipped into the sealer and slowly inserted into the canal with up and down pumping motion till reaching the working length. The excess portion of Propoint PT was cut to the level of the coronal surface of the root using Smarttrim kit, following manufacturer's instructions. The excess sealer in groups 2 and 3 was wiped using a cotton pellet wetted with alcohol.
In Group 4, the intracanal tip supplied by the manufacturer was securely attached to Smartpastebio preloaded syringe sealer (Smartseal, Stamford, UK) and inserted deeply into the root canal and then the sealer was dispensed into its apical portion. The root canal was filled while withdrawing the intracanal tip coronally.The tip of Propoint P Tsize F4 was coated with Smartpastebio and slowly inserted into the canal to the appropriate length. Excess sealer was removed with a water moisten cotton pellet and the coronal excess of Propoint PT was trimmed as in Group 3.
The quality of the obturation for all samples was evaluated radiographically and any sample showing voids or short filling was excluded and replaced by new one. All samples were then incubated for one week at 37°C and 95% humidity to allow complete setting of sealers.
The roots in the experimental and positive control groups were coated with triple layers of nail varnish, except at the coronal end and apical 1 mm of the root end. The roots in the negative control group were entirely covered with nail varnish.
Microleakage along the root canal was evaluated using the glucose leakage model as described by Xu et al. The concentrations of leaked glucose (mg/dL) were measured after 1 day and then after 1, 3, and 6 weeks with a Glucose kit (Glucose Liquid, QuimicaClinicaApplicada S.A) in a spectrophotometer (Beckman Du 520, Coulter, Germany) at a wavelength of 505 nm.
The results were statistically analyzed by Kruskal-Wallis and Mann-Whitney tests using SPSS program version 17.0 (SPSS Inc., Chicago, IL, USA). To compare leakage at different times within each group, Freidman and Wilcoxon signed ranks tests were used. All the level of statistical significance was set at a P < 0.05.
| Results|| |
The negative control group showed no detectable glucose leakage throughout the experiment, while the positive control group had immediate substantial glucose leakage which increased over time. This indicates that the seal of the glucose leakage system was effective and reliable.
Descriptive and comparative statistical results of glucose leakage obtained from the experimental groups are summarized in [Table 1] and shown in [Figure 1]. After the first day onward, there were significant differences between the experimental groups (Kruska-Wallis test, P < 0.05). The results of the Man-Whitney test showed that the Group 4 had the lowest significant amount of leakage at the end of the experimental period. Meanwhile, there was no significant difference between Groups 3 and 4.
|Table 1: Comparison of the glucose leakage mean values (mg/dL) in the experimental groups at different time intervals after obturation|
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|Figure 1: Glucose leakage mean values (mg/dL) for each experimental group at different time intervals|
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The rates of glucose leakage during observation periods within each experimental group were shown in [Figure 2]. There was a progressive and significant increase in the glucose leakage values for all experimental groups (Friedman test, P < 0.05). However, in Group 3 there was a significant decrease in glucose leakage after the 3 rd week which increased again at the end of experiment period.
|Figure 2: Rates of glucose leakage (mg/dL) within experimental groups over different time intervals|
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| Discussion|| |
In the present study, the leakage along root canal fillings was measured by the glucose penetration method which is simple and could give reliable quantitative leakage measurements. To create a standardized round root canal preparation with the same taper and size, all samples were prepared by the main author of this article using Pro Taper NiTi rotary files to size F4. ProTaper files were selected as they have a convex triangular cross-sectional design, a noncutting safety tip and an advanced flute design that combines multiple tapers within the shaft.  The manufacturer claims that ProTaper gutta-percha or Propoint PT points perfectly fit canals that have been prepared with ProTaper files and this minimizes the volume of the sealer used and, thus, the sealing quality could be improved.
Removal of the smear layer can be considered an essential step in successful root canal treatment. For this reason, the smear layer was removed in the present study using 17% EDTA irrigation and with the aid of an ultrasonic irrigating syringe. 
The glucose leakage values in all groups were lower than in the previous studies. , This may be due to the longer distance of the root canal fillings and type of glucose kit. In this study, the root canals were filled up to 15 mm as compared with the 4 mm from apex in other studies.
All obturation systems used in the current study allowed variable degrees of glucose leakage. The AH Plus Jet group had the significantly higher leakage values than that of the other groups at the end of the experimental period. This might be explained by the its fast setting and subsequent polymerization shrinkage, lack of bonding between this sealer and gutta-percha,  low penetration ability within the dentinal tubules,  and hydrophobic property that prevents good adaptation to the incompletely dried canal. 
The highest leakage values of Group 3 after the first day might be explained by the initial dentinal adaptation of GuttaFlow 2 could be adversely affected by the presence of moisture within radicular dentin and the voids present in the filling mass which leads to initial coronal leakage.  After the 1 st and 3 rd weeks, no significant difference was found between lateral condensation and GuttaFlow 2 groups. However, the overall lowest mean values for glucose leakage of GuttaFlow 2 group at the end of the experimental periods may be attributed to setting expansion, high flow rate, and lower solubility of this material. , But, some authors found that the sealing abilityof GuttaFlow/gutta-percha using single-cone technique and AH Plus/gutta-percha using the warm vertical compaction or continuous wave technique was similar.  However, other authors found that the sealing ability of AH Plus was better than that of GuttaFlow. 
The glucose leakage pattern of Smartpaste group was similar to that of Groups 1 and 2 after the first week. However, starting from the 3 rd week, this group showed a lower glucose leakage than that of Groups 1 and 2 which might be due to the hydrophilic postsetting expansion of the Propoint cone and the Smartpaste sealer. This was in contrast with the results of a recent study which indicated that the bond strength of Smartpaste sealer/Propoint to radicular dentin was similar to that of epoxy resin-based sealer combined with gutta-percha either in the lateral condensation or in the single-cone technique. 
The Smartpastebio group showed the lowest significant amount of glucose leakage at the end of observation period when compared with the other groups. This might be due to its high flowability into dentinal tubules and anatomical irregularities. , In addition, formation of apatite crystals is a common characteristic of calcium silicate containing biomaterials which develops a chemical bond with the dentinal walls.  The results of the present study are contrary to the results of Zhang et al.,  who concluded that iRoot SP (a bioceramic sealer) was equivalent to AH Plus sealer in apical sealing ability. The causes of this difference may be due to the difference in obturation materials and technique. In addition the use of matched-taper cones in canals prepared with the same tapered rotary instruments may improve the bond strength ability of root canal filling material. 
The rates of glucose leakage in experimental groups increased gradually and significantly with time. However, the Smartpaste group recorded inconsistent leakage pattern during the experimental periods. This might be attributed to the uneven hydrophilic expansion of Propoint and active polymer within the Smartpaste sealer as a result of insufficient quantity of moisture within dentinal tubules. However, Economides et al.,  in a recent study evaluated the push-out bond strength of Smartseal system and compared it with gutta-percha/AH-26 either in single cone or lateral condensation techniques. They concluded that there is no difference in adhesion to the canal walls between the Smartseal filling system and gutta-percha/AH-26 applied using either the single cone or the lateral condensation technique.
The satisfactory sealing ability of the single-cone obturation technique after using the Smartseal system specially Smartpastebio is an important property of this novel canal filling material. Bioceramic root canal sealers had additional advantages that encourage its using such as its low toxicity and strong antibacterial effect. , The use of this new filling system could be proposed in clinical endodontic practice, because of its good sealing ability, adaptability, and insolubility.
| Conclusions|| |
According to the present results, it could be concluded that:
- All single-cone obturation systems investigated in the current study did not totally prevent glucose leakage and showed progressive glucose leakage with time
- The single-cone technique utilizing matched taper Propoint PT combined with Smartpastebio showed the lowest amount of glucose leakage
- Matched taper single-cone obturation techniques used in the current study could be an alternative to the lateral condensation technique.
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[Figure 1], [Figure 2]