Real Seal Research Articles

No Evidence for DNA Double-strand Breaks Caused by Endodontic Sealers

IntroductionOn extrusion, endodontic sealers might come into close contact with the periapical tissues for long periods. The objective of this study was to test possible mutagenicity of resin-based endodontic sealers by evaluating their potential to induce DNA double-strand breaks (DSBs). MethodsHuman gingival fibroblasts were exposed to subtoxic concentrations of eluates from 1 epoxy resin–based endodontic sealer (AH Plus Jet) and 2 methacrylate-based endodontic sealers (EndoRez and Real Seal). As control, Calcicur, a Ca(OH)2-based sealer, was used. The γ-H2AX immunofluorescence assay was used to microscopically detect DNA DSBs, and a custom algorithm was developed to quantify them. ResultsThe cytotoxicity of the 24-hour eluates could be ranked in the following order: AH Plus Jet > Real Seal > EndoRez >> Calcicur. The γ-H2AX assay revealed that 1.3%–4.3% of the cell nucleus was occupied by foci when the cells were exposed to the eluates of the endodontic sealers. This was not significantly different from the negative control group in which the cells had been exposed to medium (2.1%). ConclusionsNo indications for increased risk of genotoxicity of resin-based root canal sealers caused by the induction of DNA DSBs were found in this study.

Effect of Disinfection Solutions on the Adhesion Force of Root Canal Filling Materials

IntroductionSodium hypochlorite (NaOCl) and chlorhexidine (CHX) are usually used to disinfect gutta-percha (GP) and Resilon (Res) cones. This study investigated the adhesion force (Fad) between root canal sealers and GP and Res cones following different disinfection protocols by using atomic force microscopy. MethodsNine flat surfaces of each material were obtained with medium points of GP and Res. The samples were divided into 6 groups (n = 3): control group GP, immersion in distilled water (DW); NaOCl group GP, immersion in 5.25% NaOCl and then washing with DW; CHX group GP, immersion in 2% CHX and then washing with DW; control group Res, immersion in DW; NaOCl group Res, immersion in 5.25% NaOCl and then washing with DW; and CHX group Res, immersion in 2% CHX and then washing with DW. Atomic force microscopy tips containing AH Plus sealer were used to obtain force versus distance curves regarding GP surfaces. Fad was calculated from the force curves. The same procedure was performed with Real Seal SE and Res surfaces. Data were statistically analyzed. ResultsA higher Fad between solid filling materials (GP and Res) and root canal sealers was found when CHX solution was used. Treatment with NaOCl solution did not show influence on the Fad values. ConclusionsThe decontamination of GP and Res with 2% CHX resulted in higher Fad values. The use of CHX in the disinfection process of GP and Res cones might be a better option before root canal obturation.

Biocompatibility of Root Canal Filling Materials: Differences between Vitality and Functionality Tests

Biocompatibility of root canal filling materials is of great interest because they can come into permanent contact with the living periapical tissue, and induce mild or severe inflammatory responses. Usually biocompatibility tests only determine non-cytotoxic effects of dental materials, even if their functional interactions with cells also play a role in the host responses. The purpose of this study is to evaluate peripheral blood monocyte (PBM) vitality and functionality after contact with 5 different root canal filling materials: Thermafil (gutta-percha), Real Seal and Real Seal 1 (methacrylic resins), AureoSeal (MTA) and SuperSeal (EBA). Cellular vitality was determined by MTT test and cellular functionality by Chemiluminescence (CL) technique. Dishes of the materials were covered with cell culture medium (0.5 cm2/mL) and incubated for 24 h. The extracts were added to PBMs and the latter, after 2 h of incubation, were analysed by MTT and by Chemiluminescence (CL). All results are expressed as mean ± SEM. The group means were compared by analysis of variance. Results showed that SuperSeal and AuroSeal exhibited a moderate cytotoxic effect, while the toxicity induced by RealSeal, RealSeal 1 and Thermafil was lower. SuperSeal and AuroSeal induced a significant decrease of both oxidative burst and basal reactive oxygen species (ROS) production. RealSeal 1 caused a doubling of basal ROS production in respect to control. The results demonstrate that a low cytotoxic effect does not guarantee a total integrity of cellular functionality and more differences among biocompatibility of root canal materials can be detected when a functionality test is used.

Evaluation of Apical Filling after Warm Vertical Compaction using Two Different Endodontic Materials: Resilon® and Gutta-Percha

ABSTRACT Forty-eight extracted maxillary anterior teeth instrumented with ProTaper system to apical preparations 0.25, 0.40 and 0.60 mm (n = 16 each) were divided into six groups for filling as following: Group 1: Apical preparation 25/100 + gutta-percha/AH Plus sealer, group 2: Apical preparation 25/100 + Resilon/Real Seal, group 3: Apical preparation 40/100 + gutta-percha/AH plus sealer, group 4: Apical preparation 40/100 + Resilon/Real Seal, group 5: Apical preparation 60/100 + gutta-percha/AH plus, group 6: Apical preparation 60/100 + Resilon/Real Seal. All teeth were filled using the warm vertical technique. Horizontal sections at 1, 2 and 3 mm from the apex were observed by SEM under 200 × magnification. Sections were digitally photographed under a stereomicroscope and the images were transferred to a compatible PC for image analysis. The surface area of voids were calculated and compared at all levels; using the Kruskal-Wallis test with Sidak correction and Mann-Whitney U test (p > 0.05). Comparisons within each group (gutta-percha/AH plus and Resilon/Real Seal) showed the presence of voids but there was no significant difference between any level of sectioning for apical preparations of 25 and 40 (p > 0.05). The only difference was in the groups prepared to size 60 and filled with Resilon/ Real Seal which showed significantly more voids than the group filled with gutta-percha/AH plus and especially at the 3 mm level. Conclusion The system Resilon/Real Seal did not achieve better results in terms of sealing ability in the apical third when compared to the conventional gutta-percha/AH plus sealing system. How to cite this article Zogheib C, Naaman A, Medioni E. Evaluation of Apical Filling after Warm Vertical Compaction using Two Different Endodontic Materials: Resilon® and Gutta-Percha. World J Dent 2012;3(2):166-170.

Interfacial adaptation of an epoxy-resin sealer and a self-etch sealer to root canal dentin using the System B or the single cone technique

The aim of this laboratory study was to compare the interfacial adaptation of an epoxy-resin and a self-etch sealer in mesial root canals of mandibular molars filled using the System-B/Elements Obturation Unit. Sixty mesial root canals of mandibular molars were prepared using the K3 rotary system up to 35.04 instrument and then filled with the aid of the System-B/Elements Obturation Unit using either gutta-percha/ThermaSeal Plus (n=15) or Resilon/Real Seal SE (n=15). The single cone technique using both materials was used as control. The sealers were stained with Rhodamine B dye and the teeth were filled and sectioned at 2, 4 and 6 mm from the apex. The interfacial marginal adaptation of sealers was evaluated using confocal microscopy. Statistical analyses were performed by the Kruskall-Wallis test (α=0.05). In general, microscopic analysis showed a quite regular gap distribution pattern at sealer-dentin interfaces, mainly for the two groups filled with Real Seal SE. This means that both nonbonding root-filling groups (ThermaSeal Plus) showed significantly higher amount of gap-free regions regardless of the filling technique (p<0.05). Better marginal adaptation was obtained with gutta-percha and epoxy resin-based sealer using either the system B or the single cone technique.

Influence of apical taper on the quality of thermoplasticized root fillings assessed by micro-computed tomography

The objective of this study is to study the influence of final canal taper on the sealing ability of Real Seal 1 by using micro-computed tomography (micro-CT). Fifty-four single-rooted teeth were instrumented to apical size of 40 taper 4, 6, and 8. The teeth were divided into three groups. All teeth were filled with Real Seal 1 (RS1; SybronEndo, Orange, CA, USA). Roots were then scanned with mico-CT, and volume measurements of voids in the apical third and in sections at 1, 3, and 5mm from the apex were calculated in the obturated roots using specialized CT software. Measurements were analyzed statistically by using ANOVA followed by Bonferroni multiple comparison correction. Data analysis showed that 0.08% and 0.06% apical tapered RS1 obturations provided better results than 0.04% tapered samples. The present study showed that none of the root canals filled teeth were gap free. Mean percentages of voids were significantly higher with Real Seal 1 taper 0.04% (P = 0.05).There was no significant difference with 0.06 and 0.08 final taper. For Real Seal 1 technique 0.06 and 0.08 tapered preparations seem to be more optimal. At 1mm, final taper 0.08 showed less voids and gaps than the two other final tapers. In our daily practice, enlarging the apical third (last 3mm) of root canals to an 8% taper is necessary to achieve a better sealing ability and thus long-term success for our root canal obturations.

Evaluation of the Interaction between Endodontic Sealers and Dentin Treated with Different Irrigant Solutions

Introduction Dentin surface treatment with different substances might cause alterations in chemical and structural compositions of the human dentin. The aim of this study was to investigate the wettability of endodontic sealers in contact with dentin treated with 5.25% sodium hypochlorite (NaOCl) and 2% chlorhexidine (CHX) in the presence or absence of smear layer. Methods Thirty-six dentin slices were used. They were irrigated with NaOCl and washed with distilled water (DW) to simulate irrigation during chemomechanical preparation. After this procedure, the samples were divided into 6 groups: group 1, DW (control); group 2, NaOCl + DW; group 3, CHX + DW; group 4, ethylenediaminetetraacetic acid (EDTA) + DW; group 5, EDTA + DW + NaOCl + DW; group 6, EDTA + DW + CHX + DW. The Ramé-Hart goniometer was used to measure the contact angle between the dentin surfaces and the AH Plus and Real Seal SE sealers. Data were statistically analyzed. Results With regard to the contact angle between AH Plus and treated surfaces, the values of contact angle were lower when CHX was used, regardless of the presence or absence of smear layer. When Real Seal SE was evaluated, in the absence of smear layer, CHX presented lower values of contact angle. In the presence of smear layer, the use of NaOCl and CHX did not favor the spread of the sealer. Conclusions The present study has revealed that smear layer removal and final flush with CHX favor the wettability of AH Plus and Real Seal SE sealers.

A multiparametric assay to compare the cytotoxicity of endodontic sealers with primary human osteoblasts

To compare the cytotoxicity of four endodontic sealers (Sealapex, Pulp Canal Sealer EWT, Real Seal and MTA Fillapex) either 1 or 7 days after mixing, when assessed through a multiparametric analysis employing human primary cells closely related to periapical tissues. Extracts of each sealer were prepared following 24-h exposure to culture media, at either 24 h or 7 days after mixing. Primary human osteoblasts were exposed to extracts for 24 h, at 37 °C with 5% CO(2) , and cell viability was evaluated by a multiparametric assay assessing sequentially, on the same cells, mitochondrial activity (XTT), membrane integrity (neutral red test) and total cell density (crystal violet dye exclusion test). Results from each test and experimental time were compared by 2-way analysis of variance (anova). All endodontic sealers had strong cytotoxicity 24 h after mixing, according to all parameters evaluated. At a longer setting period (7 days), viability for Sealapex was significantly increased (P < 0.05) and Pulp Canal Sealer achieved levels of cytocompatibility similar to the control group. The anova indicated a general correlation between the cytotoxicity of the materials and the time after mixing, with some level of dependence on the cell viability assay employed. All materials had high cytotoxic levels for human primary cells, mostly on a time-dependent basis, as shown by three different cell viability tests.

Bacterial and Candida albicans Adhesion on Different Root Canal Filling Materials and Sealers

Introduction Microbial adhesion and subsequent biofilm formation on endodontic root canal filling materials and sealers lead to survival of microorganisms in treated root canals and subsequently to endodontic treatment failures. The present study focused on initial microbial adhesion to different endodontic filling materials. Methods The following endodontic biomaterials were tested: AH-Plus, Tubli Seal, gutta-percha, Real Seal SE, EndoREZ, Apexit Plus, GuttaFlow, and dentin. Samples of each material were prepared. Bovine dentin samples were used as a control. The initial adhesions of salivary bacteria as well as the subsequent single species were quantified by determination of colony-forming units (CFUs) and visualized by scanning electron microscopy and confocal microscopy (CLSM): Enterococcus faecalis, Streptococcus mutans, Streptococcus sanguis, Candida albicans, and Prevotella nigrescens. Results Initially adherent microorganisms could be detected and microscopically visualized on each of the materials tested. Considering the values of the CFUs and the covering grade as detected by CLSM, there were significant differences among the materials. Fewer bacteria tended to adhere to Apexit Plus, whereas Real Seal SE and the widely used gutta-percha showed the highest number of adherent bacteria. This tendency was not detected for C. albicans. Conclusions Endodontic microorganisms have a high affinity to root canal filling materials and sealers, especially to gutta-percha. Because of this high level of bacterial adhesion, subsequent biofilm formation on these materials could be suggested as leading to the persistence of microorganisms in root canals.

Effect of Disinfectant Solutions on the Surface Free Energy and Wettability of Filling Material

Introduction Gutta-percha (GP) and Resilon (Res) cones are usually disinfected by the use of solutions such as sodium hypochlorite (NaOCl) and chlorhexidine (CHX). The aims of this study were to evaluate the surface free energy of GP and Res cones after disinfection procedures and to investigate the wettability of endodontic sealers in contact with these surfaces. Methods GP and Res flat smooth surfaces were prepared. Thirty-six samples of each material were used. The samples were divided into 6 groups as follows: Control group GP, immersed in Milli-Q water (MQW); CHX group GP, immersed in 2% CHX solution and then washed with MQW; NaOCl group GP, immersed in 5.25% NaOCl and then washed with MQW; Control group Res, immersed in MQW; CHX group Res, immersed in 2% CHX solution and then washed with MQW; and NaOCl group Res, immersed in 5.25% NaOCl and then washed with MQW. Samples were analyzed first with a goniometer to measure the contact angle between the test surfaces and 3 solutions (water, ethylene glycol, and diiodomethane) to determine the surface free energy. Then the contact angle between surfaces and each one of the sealers tested, AH Plus and Real Seal SE, was measured. Data were statistically analyzed. Results The results showed that when disinfectant solutions were used, the surface free energy was greater. When evaluating the interaction between materials and sealers, the use of CHX presented lower values of contact angle, followed by NaOCl. Conclusions It was concluded that the solutions used in decontamination increase the surface free energy, promoting high interaction between GP/Res and sealers.

Comparison of the Degree of Conversion of Resin Based Endodontic Sealers Using the DSC Technique

The aim of this study was to determine the degree of conversion (DC) of three resin based endodontic sealers using the DSC technique. THE SEALERS TESTED WERE: EndoREZ (ER) (Ultradent, South Jordan, UT); EndoREZ with Accelerator (ER+A) (Ultradent, South Jordan, UT); RealSeal (RS) (SybronEndo, Orange, CA). Two LED units were used to activate the sealers: UltraLume LED 5 (Ultradent, South Jordan, UT, USA); Mini LED Satelec (Satelec Acteon Group, Mérignac Cedex, France). Samples of 4.0 mg were analyzed with a DSC 7 calorimeter (Perkin Elmer Inc., Wellesley, MA, US). Each specimen was irradiated by each lamp four times for 20 seconds at an interval of 2 mins, while the DSC 7 recorded the heat flow developed during the treatment. The degree of conversion and the kinetic curves were calculated from the values of heat developed during each polymerization. The data were statistically analysed with a Kruskal-Wallis one-way ANOVA multiple range and Student-Newman-Keuls (SNK) tests at a P value of .05. STATISTICALLY SIGNIFICANT DIFFERENCES WERE FOUND IN THE DEGREE OF CONVERSION AMONG THE SEALERS: ER+A showed the highest values with both lamps. The higher polymerization rate in resin sealers is obtained with the addition of a catalyst.

Subcutaneous Connective Tissue Reaction to Methacrylate Resin–based and Zinc Oxide and Eugenol Sealers

Introduction An evaluation was made of the connective tissue reaction in rats after subcutaneous implantation of methacrylate resin-based sealers (EndoREZ [Ultradent Products, Inc, South Jordan, UT] with a polymerization accelerator and RealSeal [Sybron Dental Specialties, Orange, CA]) and Pulp Canal Sealer (Sybron Dental Specialties), a zinc oxide and eugenol-based sealer used as the control. Methods Silicone tubes containing the test materials were implanted in 24 Wistar rats. Solid silicone rods of the same size served as the negative controls. After 10, 30, and 90 days, the animals ( n = 8 per period) were euthanized and the implants with surrounding tissues dissected and processed for routine histological evaluation. A four-category evaluation system was used to measure and record the microscopic observations according to the thickness of a fibrous capsule, the vascular changes, and the various types of inflammatory cells. Results Initially, a severe inflammatory reaction was observed of the soft tissues in direct contact with both EndoREZ/Accelerator and Real Seal. The severity decreased over time and was resolved at the end of the experiment. Pulp Canal Sealer showed a severe tissue reaction for all observation periods. The negative controls showed an initial mild to moderate inflammatory reaction. After 30 days, healthy fibrous connective tissue was observed, which increased over time. After 10 days, no statistically significant differences between the experimental groups were observed. After 90 days, EndoREZ and RealSeal were statistically significantly less toxic than Pulp Canal Sealer ( p > 0.05). Conclusions After 90 days, both methacrylate resin-based sealers were considered biologically acceptable when implanted in subcutaneous connective tissues of the rat. Pulp Canal Sealer remained toxic for the duration of the study.

Effect of calcium hydroxide dressing on the long-term sealing ability of two different endodontic sealers: An in vitro study

The aim of this in vitro study was to evaluate the long-term sealing ability of Real Seal system and Endofill after calcium hydroxide (CH) dressing, by using a fluid filtration model. Four randomized groups of single-rooted teeth (N=110) were prepared using a crown-down technique to a size 50 file. Two groups (1 and 2) received CH dressing before filling. Roots were filled with gutta-percha and Endofill (groups 2 and 4) or Resilon and Real Seal (groups 1 and 3). Leakage was measured by using the fluid filtration method after 90 days and determined as microL/min.10 psi. Statistical analysis by Kruskal-Wallis and Mann-Whitney tests indicated that CH dressing groups showed higher leakage values than those where CH was not used (P=.001). It may be concluded that the use of CH as an intracanal dressing material affected the sealing ability of both Real Seal and Endofill sealers.

Adhesion of Self-adhesive Root Canal Sealers on Gutta-Percha and Resilon

IntroductionThe aim of this study was to evaluate the bond strength of different adhesive sealers on Resilon and gutta-percha. MethodsPellets of gutta-percha and Resilon were embedded into test tubes. Small eyelets were attached to those surfaces with a 0.5-mm film of different root canal sealers. Real Seal, Real Seal SE, Hybrid Root Seal (also known as Meta Seal), and AH Plus were used. AH Plus as a nonadhesive sealer served as a control group. In all groups (n = 10) shear bond strength was measured. ResultsShear bond strength was relatively low (0.1–3 MPa) and significantly higher in the groups with a single component adhesive sealer. No substantial bond strength was found in the control group. Overall bond strength to Resilon was higher than to gutta-percha but not significant compared with the Hybrid Root Seal group. ConclusionsWith single component self-adhesive sealers, an adhesive connection might be formed to gutta-percha as well as to Resilon.

An in-vitro evaluation of sealing ability of real seal using fluid filtration.

The aim of this study was to compare the sealing ability of Real Seal (RS) and Gutta-percha (GP). Forty nine extracted human maxillary central incisors were used. The coronal part of each tooth was removed, the root canal was prepared using the crown down technique and apical enlargement to rotary file # 40. The specimens were randomly divided in to 3 groups of 15 each and two control groups of 2 each. Group 1, was obturated with RS and group 2 and 3 were obturated with GP and AH26 sealer by lateral condensation technique. In group 1 and 3 the smear layer was removed by 5mL of 5.25% NaOCl and 3mL of 17% EDTA. Leakage of the obturated roots was measured using the fluid filtration technique. This method was done at 2 min intervals for 8 min. data were analyzed using ANOVA and Tukey tests. Statistical analysis indicated significant differences between groups 2 with 1 and 3. The most leakage value was observed in the group 2. Root canal filling with RS or GP in combination with smear layer removal showed better sealing. Therefore the smear layer has more effect one apical leakage than the obturation system.

Radiographic and rheological properties of a new endodontic sealer

A new dual-cured resin sealer has recently been proposed as an innovative endodontic filling material. Being a new endodontic material, no in vitro research has been published yet on Real Seal's (RS) physical properties. Therefore, the aim of the present study was to evaluate and compare radiopacity and rheological properties of the RS sealer with those of currently available endodontic sealers (Roeko Seal Automix and Bioseal). All tests strictly followed American National Standards Institute/American Dental Association (ANSI/ADA) specification No. 57, which indicates test methods and establishes minimal requirements of flow, film thickness and radiopacity of endodontic sealers. Results showed that significant differences were found among sealers in the different test methods. However, RS showed values complying with ANSI/ADA specification No. 57 requirements in all tests. Hence, the new RS sealer exhibited radiographic and rheological properties suitable for clinical use.

Formation of Lubricant Film in Rotary Sealing Contacts: Part II—A New Measuring Principle for Lubricant Film Thickness

The development of models for the elastohydrodynamic lubrication of rotary lip seals requires the measurement of the film thickness under a real seal. A new method has been developed for this purpose which is based on the use of lubricant oils in which magnetite particles are suspended (so-called magnetic fluids). A change in the fluid film thickness will create a change in the impedance of the coil of the measuring circuit, the magnetic flux of which is directed through the oil film of the contact area. The advantage of this technique is that minimal modifications have to be applied to the tribological system under examination. Initial measurements carried out with a model rubber lip seal provided new insight into the build-up of a lubricant film as a function of the rotary speed and allowed comparison with the results of a theoretical model for the analysis of lip seal lubrication developed in parallel.