Journal of Conservative Dentistry

ORIGINAL ARTICLE
Year
: 2011  |  Volume : 14  |  Issue : 2  |  Page : 173--177

An in vitro assessment of apical microleakage in root canals obturated with gutta-flow, resilon, thermafil and lateral condensation: A stereomicroscopic study


Sandhya Kapoor Punia1, Prasannalatha Nadig2, Vikas Punia3,  
1 Department of Conservative dentistry and Endodontics, Darshan Dental College and Hospital, Loyara, Udaipur, India
2 Department of Conservative dentistry and Endodontics, Krishna Devraya Dental College and Hospital, Bangalore, Karnataka, India
3 Department of Prosthodontics, Darshan Dental College and Hospital, Loyara, Udaipur, India

Correspondence Address:
Sandhya Kapoor Punia
Darshan Dental College and Hospital Loyara, Udaipur-313 011
India

Abstract

Aim : The purpose of this study was to evaluate and compare the apical microleakage of Resilon to Thermafil, Gutta-flow and Cold lateral condensation using a dye penetration method. Materials and Methods : Sixty extracted human maxillary single rooted teeth with intact roots were selected. Decoronation was followed by canal preparation upto ISO size 50. Teeth were then randomly divided into four groups for obturation. Group I - Cold lateral condensation with AH Plus, Group II - Gutta-flow with master cone, Group III- Thermafil with AH Plus, Group IV- Resilon with Self-etch epiphany. Apical microleakage was assessed by dye penetration test under stereomicroscope. Result : The result was analyzed statistically and showed that Resilon provides a best seal. Gutta-flow exhibited maximum microleakage. All the four groups at some level or the other exhibited some percentage of microleakage. Conclusions : None of the methods showed a fluid-tight seal.



How to cite this article:
Punia SK, Nadig P, Punia V. An in vitro assessment of apical microleakage in root canals obturated with gutta-flow, resilon, thermafil and lateral condensation: A stereomicroscopic study.J Conserv Dent 2011;14:173-177


How to cite this URL:
Punia SK, Nadig P, Punia V. An in vitro assessment of apical microleakage in root canals obturated with gutta-flow, resilon, thermafil and lateral condensation: A stereomicroscopic study. J Conserv Dent [serial online] 2011 [cited 2022 Jun 29 ];14:173-177
Available from: https://www.jcd.org.in/text.asp?2011/14/2/173/82629


Full Text

 Introduction



The objective of endodontic obturation is to provide a complete seal along the length of the root canal system, thereby ensuring the healing and sustained health of the periradicular tissue. [1]

The three main functions of obturation are: To entomb any residual bacteria in the root canal system after instrumentation. To stop the influx of periapical tissue derived fluid from reentering the root canal to feed the surviving bacteria. To seal the root canal space, preventing re-infection from coronal leakage. [2]

Gutta-percha has universally been accepted as the gold standard for root canal filling materials. However, it lacks bonding to the internal tooth structure resulting in the absence of complete seal. [2] Although lateral condensation of gutta-percha is a popular technique but studies show that it does not provide the fluid tight apical seal. [3]

Many attempts have been made to resolve this problem, as a consequence many endodontic obturation techniques, materials and sealers are available. [2]

It was hypothesized that if a dental material could be developed that would bond to the root canal walls, the material would not only provide good seal but may also reinforce the endodontically treated teeth. This led to the formulation of Resilon/Epiphany system (Pentron® Clinical Technologies, LLC Wallingford) which bonds with dentine within the root canal producing a Monoblock effect. [4]

"Thermafil" (Dentsply Tulsa dental) is a patented endodontic obturator consisting of flexible central carrier uniformly coated with a layer of α-phase gutta-percha. It is a single penetration technique with ease of placement. [5],[6]

Gutta-flow (Coltene/Whaledent, Switzerland) is the root canal filling paste which combines the sealer polydimethysiloxane with fine gutta-percha powder. It is the first sealer/gutta-percha combination which is flowable at room temperature. [7]

The objective of this study was to compare the sealing ability of Gutta-flow, Resilon/Epiphany system and Thermafil with Cold lateral condensation using dye penetration method.

 Materials and Methods



Sixty single rooted, non-carious human teeth extracted for periodontal or orthodontic reasons were used for the study. The teeth were observed under stereomicroscope and checked for the absence of immature root apices, cracks, root caries, fracture and resorption defects. After extraction, the teeth were placed in sterile physiological saline solution at room temperature, cleaned ultrasonically and sectioned at cement-enamel junction using water-cooled diamond disc.

 Instrumentation and Obturation of Root Canals



The canal length was established using 15 K file until tip of the file was visible at the tip of apical foramen. The working length was established 1 mm short of apex. Instrumentation was performed by crown-down/step-back to ISO size 50. The coronal half of the root canals were pre-flared with Gates Glidden drills in a larger to smaller sequence and the apical half was prepared with step-back technique. The canal was irrigated between each instrument with 5.25% NaOCl (NICE Chemicals, Cochin, India) and 17% EDTA alternatively. The samples were stored in distilled water until obturation. The specimens were then randomly divided into four groups of 15 specimens each.

Group I - Cold lateral condensation with AH Plus

Group II - Gutta-flow with master cone

Group III- Thermafil with AH Plus

Group IV- Self Etch Epiphany and Resilon

The obturation for each group was done following manufacturer's instructions. The obturation material was removed in all groups upto 2 mm apical to the orifice and cervically sealed with Glass ionomer cement. The samples were then placed in an incubator for 48 hours at 37 0 C and 100% humidity to allow the sealer to set.

 Apical Dye Leakage



Following obturation, the root surfaces of all samples were coated with two coats of nail paint up until the apical 2 mm. The teeth were then glued from incisal edges to lid of the petridish perpendicularly and immersed into the petridish of methylene blue, which engulfed two-thirds of the roots. The samples were then left in incubator undisturbed for 72 hrs at 37 0 C. After removing from dye solution, the specimens were washed with water and dried.

The teeth were then sectioned vertically along the long axis in the bucco-lingual direction through the centre of the root. To prevent any damage to the inside of the canal, the sectioning was done with water cooled diamond disc along the root, short of reaching the obturation material, thereby creating a stress canal. A chisel was used to wedge and split the teeth.

The samples were then observed under stereomicroscope. The dye leakage was measured with a millimeter scale from the apical constriction to the longest point of dye penetration along the canal walls and obturation material itself.

The obtained results were submitted for statistical analysis.

 Results



Multiple group comparison was done using ANOVA, and Tuckey test was used to calculate 'P' value among different test groups (P<0.001 indicates a significant difference among different groups).

The results showed that Group IV exhibited significantly less microleakage when compared to Group II and Group I. Although the microleakage of Group I was low when compared to Group III but it was not significant [Table 1] and [Table 2].{Table 1}{Table 2}

Group IV i.e., Resilon exhibited minimum and Group II i.e., Gutta-flow exhibited maximum microleakage.

 Discussion



Microorganisms present inside root canals may remain active in the dentinal tubules even after vigorous chemomechanical preparation. Thus, perfect apical sealing is desirable to prevent the remaining bacteria and their endotoxins from reaching the root apex. [8]

The microbial irritants and products of pulp tissue degeneration are the prime causes for pulpal demise and peri-radicular pathologies. Thus, the best possible cleaning and shaping coupled with an obturation technique that provides a 3-dimensional seal of the root canal system is recommended. [5]

Various endodontic materials have been advocated for obturation. Gutta-percha is by far the most universally used solid core obturation material. Although not the ideal filling material, it satisfies majority of Grossman's criteria. Gutta-percha, however, has few disadvantages like lack of rigidity and adhesiveness, ease of displacement under pressure, which are often overshadowed by its advantages.

Lateral condensation of gutta-percha has remained the most widely used method of obturating root canals and is also often used as a control for evaluating sealing ability of new obturation techniques. Its advantages include predictability, relative ease of use, conservative preparation and controlled placement of materials. Disadvantages include lack of homogeneity of gutta-percha mass, increased number of voids and sealer pools, and less adaptation to canal walls and irregularities. [9]

Gutta-flow is a modification of RoekoSeal Automix and contains gutta-percha particles in powder form, with particle size of less than 30 μm, and sealer (polydimethylsiloxane). The manufacturer claims a better seal and good adaptability because of increased flowability and the fact that this material expands slightly (0.2%) on setting, enhancing its adaptation to root dentin walls. [7]

Thermafil incorporates a central carrier coated with a-phase gutta-percha. When heated, the gutta-percha becomes thermoplasticized and adheres to the carrier. When inserted into the prepared canal, carrier transports gutta-percha in the root canal and remains in the canal as part of obturation. [10] Advantages of this technique were short time required to obturate and property of a-phase gutta-percha to replicate the canal wall. [11] Disadvantages were potential for overfilling [1] and shrinkage when gutta-percha cools, [11] gutta-percha often strips from the carrier leaving the carrier as obturating material in the apical area of the canal. [12]

Recent improvement in adhesive technology has led to the development of a new thermoplastic filled polymer, Resilon that has a potential to challenge gutta-percha as an obturation material. The advantages of epiphany system include high radiopacity, tissue compatibility, minimal shrinkage and resorbability of sealer when expressed periapically. [13]

Irrespective of different obturation materials and technique available, microleakage remains to be the most crucial cause of endodontic failure. Studies by Ingle indicated that 58% treatment failures were due to incomplete obturation. [14]

In the present study, saline was used for the storage of freshly extracted teeth because it does not influence chemical and physical properties of human dentin. [15]

An effort was made in this study to balance the composition of experimental group in terms of canal anatomy thus single-rooted teeth with single patent root canals were selected. [16] As advised by Wu et al, the canal diameter was standardized to ISO size 50 at apical constriction to have more uniform preparation for most canals. [17] Also the teeth were resected at cemento-enamel junction using water-cooled diamond disk to simplify instrumentation and obturation. [6]

The dentinal adaptation of gutta-percha and sealing effect is significantly improved in the absence of smear layer. [18] Smear layer was removed using 5.25% NaOCl and 17% EDTA. However, sodium hypochlorite has been shown to adversely affect the bond strength of epiphany sealer to root dentin. Thus, EDTA is recommended to be used as final irrigant. [19]

All samples were coated with two coats of nail paint leaving apical 2 mm to prevent dye penetration through the root surface. [11]

The quality of apical seal obtained by root canal obturation material has been assessed by various methods like dye penetration, radioisotope penetration, bacterial leakage, fluorometric and electrochemical means, fluid filtration, scanning electron microscope and gas chromatography. [9] The dye penetration was used because of its simplicity, ease to perform and it does not require sophisticated materials. [20] Methylene blue dye was used as its molecular size is similar to bacterial by-products such as butyric acid which can leak out of infected root canals to irritate periapical tissues. [20]

The teeth were placed vertically in the dye because in a study by Melvin et al, when teeth were placed horizontally in the dye, the air was trapped in the middle and did not allow the dye to penetrate fully. [21]

Longitudinal sectioning of roots and linear measurement of dye penetration were used to measure apical leakage. Alternative methods are vertical sectioning or clearing the roots. Vertical sectioning is more destructive than longitudinal sectioning. Clearing although visually impressive has never been satisfactorily verified to completely demonstrate the pattern of tracer penetration as it is difficult to measure precisely and the tracer may be lost during the tissue processing. [9] The advantage of splitting technique is that it enables the observation of dye penetration. [22]

Our results showed that the Resilon/Epiphany System appears to be superior to Thermafil and gutta-flow in apical sealing. This may be attributed to the monoblock provided by adhesion of the filling material to the sealer which also adheres and penetrates into the dentin wall of the root canal system. [20]

Although it exhibits monoblock effect still leakage was observed, which may be attributed to inadverdent stripping of the sealer off the canal wall during placement of cones, disruption of the maturing resin-root dentin bond during cold lateral condensation or the C-factor. [4] The manufacturer's instruction for immediate light-curing the coronal root filling to create a coronal seal may also limit flow of the resin sealer for stress relief. [13]

The mean leakage with Resilon/Epiphany system was lower than that for gutta-percha with AH plus sealer. The difference may be because of lack of bonding between gutta-percha and sealer. [23]

The results of the present study are supported by similar results concluded by other studies. [2],[4],[20],[23]

Thermafil technique resulted in obturation that adapted well to the canal walls which would have resulted in the less amount of microleakage compared to lateral condensation. [18] However, thermafil exhibited dye penetration, due to probable mass shrinkage of gutta-percha after it cools down. [3]

In this study cold lateral condensation showed less mean microleakage compared to Guttaflow. This can be attributed to better sealing ability of AH Plus sealer. Moreover, it has been reported that AH-Plus expands slightly during setting in liquid environment. [24]

Gutta-flow exhibited maximum apical leakage, which is consistent with other studies. [24] It can be due to: its poor wettability of dentin, lack of leak-free seal between gutta-percha particles and sealer, and absence of chemical union between gutta-percha particles and gutta-percha master cone. [25]

The result in the present study showed that Resilon provides a better consistent seal as compared to either Cold lateral condensation, Thermafil, or Gutta-flow techniques. However, further long-term studies are required for evaluating sealing ability of Gutta-flow.

 Conclusions



Within the limitations of this study following conclusions were drawn:



All four groups showed microleakage and none of the methods were able to achieve fluid-tight seal.Mean microleakage value was maximum for Gutta-flow group, followed by Cold lateral condensation, Thermafil and Resilon/Epiphany system.Though there was a difference in the mean leakage values, it was not statistically significant except between Resilon/Epiphany and Gutta-flow.The result in the present study showed that Resilon/Epiphany provides a better seal as compared to cold lateral compaction, Gutta-flow or Thermafil technique.Further long-term in vivo studies are required for evaluation of sealing ability of Resilon/Epiphany system.

 Acknowledgment



We are thankful to Late Dr. Gururaj Nadig for his guidance and support.

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