COMPARATIVE EVALUATION OF ROOT CANAL FILLING QUALITY OF NEWLY DEVELOPED ENDODONTIC SEALERS APPLIED USING GUTTA-PERCHA CONE MEDIATED ULTRASONIC ACTIVATION: AN IN-VITRO STUDY

Yogesh Damade, Sunanda Gaddalay, Ramchandra Kabir, Sharvaree Deshpande, Anita Kale and Deepak Nagargoje Department of Conservative Dentistry and Endodontics, MIDSR Dental College and Hospital, Latur, Maharashtra, India. Pin code – 413512. ...................................................................................................................... Manuscript Info Abstract ......................... ........................................................................ Manuscript History Received: 12 February 2020 Final Accepted: 14 March 2020 Published: April 2020


ISSN: 2320-5407
Int. J. Adv. Res. 8(04), 568-575 569 and does not adhere to canal wall dentin. Therefore it is necessary to use a sealer to increase the sealing ability of gutta percha. Several root canal sealers are currently available. Endodontic sealers are used in order to achieve a fluid-tight seal between the dentinal wall and core filling material. One such sealer is Mineral trioxide aggregate (MTA).
MTA is composed of calcium, silica, and bismuth. it has been widely used in variety of applications such as rootend filling, perforation repair, or apical/coronal sealing material during regenerative endod ontic procedures, pulp capping, pulpotomy, apical barrier formation in teeth with open apexes (Parirokh M et al, 2010). It has a long setting time, high pH, and low compressive strength. It possesses some antibacterial and antifungal properties, depending on its powder-to-liquid ratio (Parirokh m et al 2010). As MTA is hydraulic hydrophilic, it can be used to reduce fluid flow rate and seal the apex in teeth with wide open apices (Prati C et al, 2014;Kim H et al, 2016) and can use the natural moisture in the root canal, (Kim J et al, 2020). Such characteristic features of mta appear to be important in biomineralization of dentinal tubules for enhanced sealing of the root canal system making it a good candidate for root canal filling (Yoo Y et al, 2016). However, it cannot be recommended as a routine sealer or root canal filling material because of its disadvantages such as difficulty in filling of complicated root canal system, long setting time (Lee J et al, 2017), (Yazdi K et al, 2019), sandy property and irretrievability of the material in retreatment cases (Kim J et al, 2020).
A recently developed variant of MTA is the Endoseal MTA (Maruchi, Wonju, Korea). It is a pozzolan -based MTA which is premixed and preloaded in an air-tight syringe, and can be applied directly into the root canals. (Moazami F et al, 2020). It is composed of calcium silicates, calcium aluminates, calcium aluminoferrite and calcium sulfates. The main component of this sealer, the pozzolan cement, gets its cementitious properties after pozzolanic reaction which includes calcium hydroxide and water, and enables sufficient flow of the pre-mixed substrate though injection tips with adequate working consistency. (Yoo Y et al, 2016 Another new root canal sealer containing calcium silicate is GuttaFlow Bioseal (Coltène, Switzer land), also known as GuttaFlow 3. It is composed of gutta-percha, polydimethylsiloxane, zirconium oxide, platinum, and bioactive ceramic glass. GuttaFlow Bioseal was developed to improve the bioactivity of GuttaFlow (Reszka P, 2019). It has the same formulation as the GuttaFlow sealer but also includes calcium silicate, which, upon contact with biological tissues, releases natural repair constituents and aids in the regeneration of periapical tissues. It provides repair along with obturation (Camargo RVD et al, 2017;Reszka P et al, 2019). Complementary analysis by means of atomic absorption spectrometry showed release of sodium ions from GuttaFlow Bioseal. This is due to the addition of bioactive glass ceramics. Calcium and sodium ion released, increase the pH of the dental environment and prohibits bacterial viability (Camargo RVD et al, 2017). Hoikkala N-PJ et al (2018) reported that GuttaFlow BioSeal exhibited significantly higher water sorption and solubility in comparison with Guttaflow 2. The exposed particles of bioglass ceramic particles release ions into the surrounding media, thereby increasing the pH to 7.9 which causes antimicrobial effects. Biomineralization occurs on the surface of the sealer suggesting that the precipitation is hydroxyapatite (Hoikkala N-PJ et al, 2018). Histopathologic evaluation revealed that GuttaFlow sealers were more cytocompatible than AH Plus and MTA Fillapex, while GuttaFlow Bioseal favored cementoblast differentiation of human periodontal stem cells in the absence of any growth factors (Rodríguez-Lozano F et al, 2019).
Through the development of new endodontic sealers and tests, evaluation and knowledge about them may be enhanced. The aim of this study was to evaluate the root canal filling quality of two recently developed endodontic sealers Endoseal MTA (Maruchi, Korea) and GuttaFlow Bioseal (Coltene, Switzerland) in comparison with AH Plus, using Gutta-percha cone mediated ultrasonic activation.

Materials And Methods:-
Sample of fifty human single-rooted freshly extracted mandibular premolars were selected. Access cavity was prepared and a size 10 K-file was used to determine the working length 0.5 mm short of the radiographic apex. The root canal cleaning and shaping were done with Protaper rotary files till F3 preparation. Canals were irrigated with 5 ml of 5.25 % sodium hypochlorite, 5 ml of 17% EDTA and followed by normal saline. Root canals were dried with 570 absorbent paper points. At the end of the preparation, the samples were randomly divided into five groups, with 10 specimens each. The five different protocols used were: Group A: EMS (Endoseal MTA + single cone without ultrasonic activation) Group B: EMSU (Endoseal MTA + single cone with ultrasonic activation) Group C: GBS (GuttaFlow Bioseal + single cone without ultrasonic activation) Group D: GBSU (GuttaFlow Bioseal + single cone with ultrasonic activation) Group E: APW (AH plus + warm vertical compaction) The files were frequently cleaned to remove debris from their flutes, and the irrigating solutions were frequently replaced to maintain effectiveness. During obturation, tug back was checked at the working length and confirmed radiologically. The EMS and GBS sealers which come in pre-mixed syringes with injection tips were inserted into the canals. The root canals were completely covered by the sealer. In the groups of ultrasonically activated sealers (EMSU, GBSU), activation was performed immediately after sealer placement using an ultrasonic tip attached to an ultrasonic device. In EMS, EMSU, GBS, GBSU groups a single cone was inserted upto the working length. In APW group, the AH Plus sealer (Dentsply, Maillefer, North America) was manipulated according the manufacturer's instructions and inserted into the root canals followed by warm vertical compaction of gutta percha. After obturation, all experimental samples were stored at 37 •C and 100% humidity for 24 hours to allow the sealers to set. Later, they were sectioned perpendicular to the longitudinal axis of root at 4mm of distance at the level of coronal, middle and apical third using a slow speed diamond wheel.
Each assigned slice was observed under Digital Stereomicroscope (Nikon eclipse E200 Japan) under a magnification of 40x. Digital image of each segment was taken and were observed to estimate the number of voids. Filling quality (number of voids) was assessed by a single blinded and caliberated examiner. Numbers of voids present were counted under a scoring system of each section and the mean void scores were calculated (Kim J-A et al, 2018).
Scoring criteria for evaluating the filling quality of various sealers 1. Score 0: No voids. 2. Score 1: Well-condensed filling that showed only a few, minor air bubbles less the (less than 0.1mm in diameter). 3. Score 2: An imperfectly condensed filling that showed some minor air bubbles (more than 3 defects) or medium sized air bubbles (0.1 mm to 0.2 mm in diameter). 4. Score 3: Inadequately condensed filling that showed many minor air bubbles (more than 5 defects) or large air bubbles (more than 0.2 mm in diameter). 5. Score 4: Poorly condensed filling that showed many minor air bubbles (more than 7 defects) or empty space connecting separate canal walls.
Statistical analysis was performed (with SPSS software) and descriptive statistics were calculated. Intergroup comparison was done using one way ANOVA at coronal, middle and apical thirds. Post hoc tests were done to compare mean difference between individual groups. P value of <0.05 was considered to be statistically significant. Table 1, 2 and 3 show the mean void scores among the various groups in the coronal, middle and apical thirds respectively. Least mean void score was found in Group E (APW), followed by Group B (EMSU) in the coronal, middle and apical thirds, which was found to be highly statistically significant (p=0.0001). Maximum mean void score was found in the Group C (GBS), followed by Group D (GBSU).

Results:-
Post hoc Tukey's test showed the mean difference between EMS and APW, GBS and APW, GBSU and APW, and EMSU and GBS groups to be statistically significant (p<0.05) at the coronal thirds. Significant difference was found between EMSU and GBS, EMSU and GBSU, GBS and APW, and GBSU and APW in middle thirds and between EMS and APW, GBS and APW, EMSU and GBS, EMSU and GBSU, and GBSU and APW groups in the apical third (p<0.05). APW showed lesser voids compared to EMS and GBS (P<0.05).
In coronal third, no statistically significant difference was found between EMS and EMSU, EMS and GBS, GBS and GBSU, EMSU and GBSU, EMSU and APW. It indicates that EMSU may be as effective as APW in the coronal third (p>0.05).

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Similarly, there is no statistically significant difference between EMS and EMSU, EMS and GBS, EMS and APW, EMSU and APW, GBS and GBSU, in the middle third, indicating that EMS is as effective as GBS and APW with or without ultrasonic activation (p>0.05)..
In the apical third, no statistically significant difference was found between EMS and EMSU, EMS and GBS, EMSU and APW, GBS and GBSU (p>0.05). This indicates that when EMS is used alone, it has higher voids compared to APW, but is as effective as APW when used along with ultrasonic. Since there is no statistically significant difference between EMSU and APW at all three levels (coronal, middle, apical), it implies that EMS is as effective as APW under ultrasonic activation. Ultrasonic activation has shown no effect on lowering void score in between EMS and EMSU and GBS and GBSU groups (p>0.05).      Figure 1 shows the mean void scores among the five treatment groups. Apical third showed better sealing of voids and better condensation compared to middle and coronal thirds across all the groups.

Discussion:-
Bio-ceramics are amongst the recently introduced materials in endodontics. They are biocompatible ceramic materials or metal oxides with enhanced sealing ability, and antibacterial and antifungal properties. They achieve excellent hermetic seal, form a chemical bond with the tooth structure and have good radiopacity (Raghavendra SS et al, 2017). Dr.Torabinejad in 1993 successfully introduced a bioceramic material in endodontics known as MTA (Raghavendra SS et al, 2017). It was recommended initially as a root-end filling material and subsequently has been used for pulp capping, pulpotomy, apexogenesis, apical barrier formation in teeth with open apexes, repair of root perforations, and as a root canal filling material.
In the present study, APW showed lesser voids compared to EMS and GBS. Though there was no effect of ultrasonic activation on void scores among EMS and EMSU, EMSU showed similar voids scored as APW. These results are similar to a study done by Kim

Conclusion:-
Endoseal MTA, when used along with ultrasonic activation shows promising results, which are comparable to AH plus. Without ultrasonic activation EMS and GBS groups performed poorly compared to APW group. Ultrasonic activation showed no effect on lowering void scores in the EMS and GBS groups (p>0.05). Clinical trial tests and long term follow-up studies using various types of the sealers would be highly valuable to evaluate the sealers' clinical performances. Though the results are satisfactory, further research and scientific studies are needed to confirm them.

Ethical considerations:
The research protocol was approved by the Institutional Ethics Committee of MIDSR Dental College and Hospital, Latur, Maharashtra, India.