In vitro evaluation of apical microleakage of a new MTA-based sealer.
Obturation of the root canal system hermetically, both apically and coronally is a crucial factor for clinical success of root canal therapy. There are many reasons why the root canal space must be obliterated during obturation. The main reason is that; spaces between the root-canal filling and canal wall may harbour micro-organisms, which could lead to irritation of periapical tissue. Increased sealer penetration may eliminate any remaining bacteria and prevent them from repopulating the canal space and causing further peri-radicular disease. In some studies, it has been stated that leakage mostly occurs between the filling material and the root canal walls. The degree of leakage could be reduced by using a material that adapts well to the root canal walls [Ingle et al., 2002; Sagsen et al., 2006].
Leakage studies on the sealing properties of endodontic materials, have an important place in research [Economides et al., 2004]. Currently in dentistry, there are a great variety of materials used. Different types of sealer have been introduced with new products having better physical properties than commonly used materials [Belli et al., 2008]. MTA Fillapex (Angelus, Londrina PR, Brazil) is a new paste-paste MTA-based root canal sealer with a high sealing capacity and it is the only root canal sealer that promotes cementum regeneration, according to the manufacturers. However, no data is available regarding the apical microleakage of MTA Fillapex.
The most commonly used sealer to date is AH Plus, which is an epoxy-resin-based sealer having excellent sealing properties [Belli et al., 2008], and considered as a gold standard against which all new sealers must be compared [Brackett et al., 2006]. The base material of MTA Fillapex, mineral trioxide aggregate (MTA); is composed of Portland cement, bismuth oxide, and dehydrated calcium sulphate. Owing to its clinical behaviour related to its biocompatibility, antimicrobial behaviour, sealing abilities, and its inducing tissue healing, its application has been extended by some authors to root-canal filling [Holland et al., 1999; Shabahang and Torabinejad 2000; Holland et al., 2001; Jacobovitz and Lima 2008; Jacobovitz et al., 2009]. There is no study investigating the apical microleakage of MTA filling including the apical third of a root canal. Therefore, this study aimed to evaluate the apical microleakage of MTA Fillapex and compare it with another widely used root canal sealer AH Plus and the base material MTA of the new sealer.
Materials and Methods
Fifty-one extracted single-rooted human permanent incisors were used in this study. Teeth with caries, cracks and immature apices were excluded. All teeth were radiographed on the buccal and proximal aspects to check for a single root and single canal. Each tooth was sectioned at the cemento-enamel junction with a water-cooled diamond bur. Working length was determined using a K-file #10, until it reached the apical foramen, subtracting 1 mm from this measurement. The roots were prepared with Mtwo NiTi rotary system (VDW) to apical size #40, 5.25% NaOCl was used for irrigation between each instrument and the smear layer was removed after instrumentation with 15% ethylenediaminetetraacetic acid (EDTA). Finally, root canals were flushed with distilled water and dried with paper points before obturation. The teeth were randomly divided into three groups of 15 specimens each and the remaining six roots were used as positive (n = 3) and negative (n=3) controls (groups IV and V respectively).
Group I: AH Plus (Dentsply, Konstantz, Germany) and guttapercha (Diadent, Choongchong Buk Do, Republic of Korea) using lateral condensation technique
Group II: MTA Fillapex (Angelus, Londrina PR, Brazil) and gutta-percha using lateral condensation technique
Group III: Pro Root MTA (Dentsply, Konstantz, Germany)
Group IV: Gutta-percha using lateral condensation technique without a sealer (positive control)
Group V: Root canals remained empty (negative control)
The tested materials were handled according to the manufacturers' instructions. ProRoot MTA (group III) was placed into the canals with the aid of a lentulo spiral (Dentsply, Konstantz, Germany) and then by using pluggers the material was condensed vertically. The use of MTA as a sealing material was difficult because of the poor handling characteristics of the material. After canal obturation, the teeth were radiographed to make sure the canals were fully obturated. The teeth were stored at 37[degrees]C with 100% humidity for one week to allow the sealers to fully set.
All root surfaces except the apical 2 mm were covered with two layers of nail varnish. The root surfaces of the negative controls were completely coated with two layers of nail varnish, being sure to include the apical foramen, to test the impermeability of nail varnish to methylene blue. Afterwards, the area protected with the varnish was coated with a layer of sticky wax. The teeth were then immersed in an aqueous solution of 2% methylene blue dye, stored in an incubator, at 37[degrees]C for 72 h.
Following exposure to dye, the roots were rinsed in running water and dried with paper towels. The varnish and sticky wax coatings were removed with a scalpel blade and a guide groove was prepared with a diamond disc in a crown-apex direction on both buccal and lingual surfaces almost to the depth of the canal. Roots were longitudinally split using a large spoon excavator. Linear dye penetration was measured from apical root surface to the most coronal extent of dye penetration. Two experienced examiners calibrated for the technique and blinded to the groups, measured penetration by using a digital caliper under 30X magnification with an illuminated microscope.
Measurements were analysed statistically by one-way ANOVA and Tukey's test. Statistically significant differences among the groups were set at p < 0.05.
All experimental groups (I-III) demonstrated dye microleakage. The three positive control specimens showed total dye penetration whilst the three negative control specimens showed no evidence of dye penetration.
The mean microleakage values (mm) of the experimental groups were calculated and are shown in Table I. The MTA Fillapex group (II) had significantly higher microleakage values than the other two groups (p < 0.05). ANOVA test showed statistically no significant differences among Pro Root MTA (Group III) and AH Plus groups (Group 1), (p > 0.05).
The dye penetration test is the most popular among several methods, probably as it is a simple [Limkangwalmongkol et al., 1991; Farea et al., 2010] and reliable method [Conrado et al., 2004; Farea et al., 2010]. Furthermore, if a filling material does not allow penetration of small molecules such as dyes, it is likely that it has potential to prevent leakage of larger molecules, such as bacteria and their by products [Torabinejad et al., 1993; Kubo et al., 2005]. Methylene blue, used in our study, is a small molecular weight dye which has a high penetration ability [Boussetta et al., 2003].
A 3-day immersion period was used in the present study, as the protocol did not involve an additional active penetration device such as a vacuum. It has been reported that elimination of air may induce an overestimation of the in vivo extent of microleakage [Haikel et al., 1999]. Additionally, all the root canals were prepared to the same final apical size and both the preparation and obturation steps were conducted by the same operator.
In the current study, the experimental system was tested by using positive and negative control groups. The positive control group indicated that leakage testing was a suitable method for proving total dye penetration without a sealer. The negative control group showed no dye penetration indicating using two layers of varnish is effective to prevent dye penetration [Oliver and Abbott 1998].
MTA materials have demonstrated acceptable biocompatible behaviour and also exhibited acceptable in vivo biologic performance when used for root-end fillings, perforation repairs, pulp-capping and pulpotomy, and apexification treatment in children [Roberts et al., 2008]. MTA Fillapex is a new paste-paste MTA-based root canal sealer. According to the manufacturers its MTA-based composition provides a perfect sealing, sealing integrity and high biological regeneration. Therefore, using an MTA-based sealer might be considered for use in children's teeth.
There are a few studies and case reports using MTA in the mature apices to seal complete root canal space [Panzarini et al., 2007; Bogen and Kuttler 2009; Brito-Junior et al., 2010]. A case series was reported in the literature regarding the concept of MTA obturation of the entire canal system. The case showed that endodontically treated teeth which had been subjected to long-term microleakage and bacterial contamination could show improved healing rates without surgical intervention by using MTA obturation [Bogen and Kuttler 2009]. In a previous study, MTA was used as a root canal filling material in reimplanted teeth in monkeys. According to the results of the research, most specimens presented organised periodontal ligaments with no inflammation. Researchers reported that MTA was a good root canal filling material for immediately reimplanted teeth, providing good repair and also allowing biological sealing of some lateral canals [Panzarini et al., 2007].
Additionally, a case has been reported of a non-surgical endodontic management using MTA for perforative defects of internal root resorption. In the case report, the root canal space and the perforation defect were filled with MTA. Researchers were agreed on the use of MTA as a conservative approach [Brito-Junior et al., 2010]. Although it has not been produced for use as a root canal filling material, these studies suggest using MTA for filling the entire root canal space. The aims of testing MTA in this study are to represent apical sealing ability of MTA when used as a root canal filling material and to compare it with the new MTA-based sealer; MTA Fillapex.
Various methylene blue dye penetration studies reported excellent sealing ability for MTA. However, these studies displayed its superiority when compared with the other root-end filling materials [Torabinejad et al., 1994; Aqrawabi 2000; Pereira et al., 2004; Gondim et al., 2005; Asgary et al., 2008]. There has been no study investigating the apical microleakage of MTA when used to completely fill the root canal space of teeth with mature apices, compared with root canal sealers filled with gutta-percha.
AH Plus is considered as a gold standard to be compared with all new sealers [Brackett et al., 2006; Belli et al., 2008], as it is the most widely used sealer having excellent sealing properties [Belli et al., 2008]. Therefore, in the present study we aimed to compare MTA and the new sealer, with AH Plus.
According to the results of this study, Pro Root MTA and AH Plus groups had similar microleakage values. However, some characteristics of MTA cements make its use difficult for such an application; sandy consistency (poor handling characteristics), low viscosity and high cost [Jacobovitz et al., 2009].
MTA Fillapex group leaked more at the coronal portion of the root than the other two groups (p < 0.05). MTA Fillapex is a new material, thus, there is no study comparing this new material with AH Plus. A previous study investigated an MTA-based sealer to a zinc oxide eugenol sealer [Camileri et al., 2011]. This study investigated the sealing ability of a novel sealer based on MTA; mineral trioxide aggregate sealer (MTAS), reported that MTAS has a sealing ability similar to zinc oxide eugenol sealer (Pulp Canal Sealer (PCS)). Another study, evaluating the long-term sealing ability of Pulp Canal Sealer (PCS) compared with AH-Plus after 1 year of storage showed that PCS leaked significantly more than AH-Plus [Bouillaguet et al., 2008]. Furthermore, Almeida et al.,  in their microleakage study that compared five sealers including Pulp Canal Sealer (PCS) and AH Plus; reported that AH Plus permitted less leakage than Pulp Canal Sealer. According to the results of our study the MTA-based new material displayed more microleakage than AH Plus.
According to the results of our study; MTA Fillapex had an inferior apical seal compared with AH Plus and MTA. The sealing ability of MTA was similar to AH Plus. However, future research is recommended to evaluate the sealing ability of the new sealer, MTA Fillapex.
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I.S. Sonmez *, A.A. Oba **, D. Sonmez ***, M.E. Almaz **
* Adnan Menderes University, Faculty of Dentistry, Department of Paediatric Dentistry, Turkey. ** Kirikkale University Faculty of Dentistry, Department of Paediatric Dentistry, Turkey. *** Medicana International Ankara Hospital, Turkey.
Postal address:: I.S. SONMEZ, Kirikkale Universitesi, Dic Hekimligi Fakultesi, Pedodonti AD, Kirikkale, Turkiye.
Table 1. Mean linear dye penetration (mm) in root canals. Group sealer N Mean [+ or -] std. Range Deviation (mm) I AH Plus 15 4,49 [+ or -] 1,36 (a) 2,97-7,56 II MTA Fillapex 15 8,29 [+ or -] 2,42 (b) 3,1-10 III Pro Root MTA 15 4,64 [+ or -] 2,76 (a) 2,63-10 * Groups with the same superscripted letters had no significant difference (p > 0.05).
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|Author:||Sonmez, I.S.; Oba, A.A.; Sonmez, D.; Almaz, M.E.|
|Publication:||European Archives of Paediatric Dentistry|
|Date:||Oct 1, 2012|
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