Resin-based Root Canal Sealer Research Articles

Polymerization stress, flow and dentine bond strength of two resin‐based root canal sealers

To compare two resin-based root canal sealers (AH Plus and dual cure Epiphany) in terms of flow, polymerization stress and bond strength to dentine. Flow was evaluated by measuring the diameter of uncured discs of sealer (0.5 mL) after 7 min compression (20N) between two glass plates (n = 5). Polymerization stress was monitored for 60 min in 1-mm thick discs bonded to two glass rods (Ø = 5 mm) attached to a universal testing machine (n = 3). Bond strength was analyzed through micropush-out test (n = 10) and failure mode was examined with scanning electron microscope (100x and 2500x). Data were statistically analyzed using the Student's t-test (alpha = 0.05). Polymerization stress was 0.32 +/- 0.07 MPa for Epiphany self-cure, 0.65 +/- 0.08 MPa for Epiphany light-cure and zero for AH Plus (P < 0.05). Flow data and bond strength values were 30.9 +/- 1.1, 28.6 +/- 0.7 mm and 6.3 +/- 5.3, 17.8 +/- 7.5 MPa for Epiphany and AH Plus, respectively (P < 0.001). Failure mode was predominantly cohesive in the sealer for both materials. Epiphany had higher flow and polymerization stress and lower bond strength values to dentine than AH Plus. In view of these findings it can be implied that AH Plus would provide a better seal.

Can Radiotherapy Affect the Apical Sealing Ability of Resin-Based Root Canal Sealers?

The authors conducted a study to assess the influence of radiotherapy on the apical sealing ability of one recently introduced resin-based root canal sealer and two sealers that have been in use for several years. The authors divided 90 human maxillary anterior teeth into three groups according to the type of root canal sealer used and, using lateral condensation, obturated the roots with gutta-percha. They randomly divided all roots into two main groups according to the presence or absence of radiotherapy. For the groups that received irradiation, a dose of 60 gray was delivered in fractions of 1.8 Gy per day, five days a week for seven weeks. The authors then performed the centrifuging dye penetration test to determine apical leakage for each specimen. The authors compared the specimens in the groups that received radiotherapy after endodontic treatment with the specimens in the groups that did not undergo radiotherapy after endodontic treatment. They found that mean apical leakage was slightly higher in the radiotherapy groups, but they did not observe any statistical difference between the groups (P > .05). In the groups that did not undergo radiotherapy, the mean apical leakage for the specimens in the MM-Seal (MicroMega, Besançon, France [not marketed in the United States]), AH Plus (Dentsply DeTrey GmbH, Konstanz, Germany) and AH 26 (Dentsply DeTrey GmbH) groups was 2.52 +/- 0.42 millimeters, 2.85 +/- 0.52 mm and 3.73 +/- 0.41 mm, respectively. In the groups that underwent radiotherapy, the mean apical leakage for the specimens in the MM-Seal, AH Plus and AH 26 groups was 2.72 +/- 0.55 mm, 2.96 +/- 0.47 mm and 3.93 +/- 0.61 mm, respectively. The apical sealing ability of the resin-based root canal sealers decreased slightly when radiotherapy was administered, although there was no statistically significant difference. Clinicians can safely use a resin-based root canal sealer in patients receiving radiotherapy.

Scanning electron microscopic and coronal leakage evaluation of self-adhesive resin-based root canal sealers

Scanning electron microscopic and coronal leakage evaluation of self-adhesive resin-based root canal sealers

Contemporary Methacrylate Resin–based Root Canal Sealers Exhibit Different Degrees of Ex Vivo Cytotoxicity When Cured in Their Self-cured Mode

The cytotoxicity of four methacrylate resin–based sealers was investigated by the 3-(4,5-dimethyl-thiazoyl)-2,5-diphenyl-tetrazolium bromide assay, which measures cell viability by assessing its succinate dehydrogenase activity. The sealers were polymerized in the self-cured mode to simulate the setting condition upon their extrusion into periradicular tissues. Disks were prepared from EndoREZ (Ultradent, South Jordan, UT), RealSeal (SybronEndo, Orange, CA), MetaSEAL (Parkell, Farmington, NY), and RealSeal SE (SybronEndo) together with positive and negative controls. After setting, they were placed in direct contact with rat osteosarcoma (ROS 17/2.8) cells and for 5 succeeding weeks after immersing in simulated body fluid (SBF). All sealers exhibited severe toxicity initially (week 0). EndoREZ and RealSeal remained severely toxic after five cycles of SBF immersion. Toxicity of the two self-etching resin-based sealers MetaSEAL and RealSeal SE decreased gradually over time. Transmission electron microscopy of cells exposed to RealSeal SE showed variable degrees of cell injury that reflect its toxicity status. Cells with intact mitochondria were identifiable after the sealer became noncytotoxic at week 5.

Evaluation of the Radiopacity of New Root Canal Paste/Sealers by Digital Radiography

The aim of the present study was to assess the radiopacity of new polydimethylsiloxane-based root canal filling paste (GuttaFlow; Coltène/Whaledent, Langenau, Germany) and resin-based root canal sealer (Adseal; Meta Biomed Co, Cheongju, Korea) and compare their radiopacity with three currently used root canal sealers (AH Plus [Dentsply DeTrey GmbH, Konstanz, Germany], Epiphany [Pentron, Wallingford, CT], and Diaket [3M ESPE AG, Seefeld, Germany]) by means of direct digital radiography. Six specimens, 5 mm in diameter and 1 mm high, were performed for each material tested. After the material set, radiographs were made by using a digital sensor and a graduated aluminum stepwedge varying in thickness from 1 to 14 mm. These samples were tested according to the international standards to compare their radiodensity to that of the aluminum stepwedge. Data were analyzed using analysis of variance and Tukey tests. The millimeters of aluminum values reported in this study were 10.41, 8.20, 6.50, 4.90, and 3.09 for AH Plus, Epiphany, Diaket, GuttaFlow, and Adseal, respectively. Although the materials evaluated had different radiopacities, all of them showed radiopacity above the minimum recommended by the International Organization for Standardization and the American National Standards/American Dental Association.

In Vitro Cytotoxicity Evaluation of a Self-adhesive, Methacrylate Resin–based Root Canal Sealer

This study compared the cytotoxicity of MetaSEAL (Parkell Inc, Farmington, NY), a methacrylate resin-based sealer with an epoxy resin-based (AH Plus Jet; Dentsply Caulk, Milford, DE) and a zinc oxide–eugenol-based sealer (Pulp Canal Sealer; SybronEndo, Orange, CA). Five-millimeter diameter disks prepared from the respective sealer and disks prepared from Teflon (negative control) and polymethyl methacrylate (positive control) were placed in direct contact with a rat osteosarcoma (ROS) 17/2.8 rat osteoblast-like cell line at six intervals after setting completely at 72 hours and for 5 succeeding weeks after the disks were immersed in simulated body fluid. Succinate dehydrogenase activity was evaluated by using 3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyl tetrazolium bromide assay. All sealers exhibited severe toxicity at 72 hours, after which toxicity decreased gradually over the experimental period except for Pulp Canal Sealer, which remained severely toxic. MetaSEAL was more toxic than AH Plus Jet during the first week. Both were similar to the toxicity profile of the positive control after the first week, which was probably diffusion controlled.

Up-regulation of Gelatinases and Tissue Type Plasminogen Activator by Root Canal Sealers in Human Osteoblastic Cells

Histologic investigations have demonstrated that root canal sealers can induce mild to severe inflammatory alternations. However, there is little information on the precise mechanisms about root canal sealer–induced inflammatory reaction. The proteolysis of extracellular matrix by matrix metalloproteinases (MMPs) and plasminogen activators (PAs) seems to be a key initiating event for the progression of the inflammatory process. The aim of this study was to investigate the effects of epoxy resin–based root canal sealer AH26 and zinc oxide–eugenol–based root canal sealer Canals and one paste sealer N2 on the expression of MMPs and PAs in human osteoblastic cell line U2OS cells. The levels of gelatinolytic and caseinolytic activities were measured by gelatin and casein zymography. The results showed that AH26, Canals, and N2 were cytotoxic to U2OS cells in a concentration-dependent manner ( P < .05). The gelatin zymograms revealed that MMP-2 (72 kd) and MMP-9 (92 kd) were secreted by U2OS cells. The exposure of U2OS cells to root canal sealers resulted in the up-regulation of MMP-2 and MMP-9 expression ( P < .05). Casein zymography exhibited a caseinolytic band with a molecular weight of 70 kd, indicative of the presence of tissue type plasminogen activators (t-PA). t-PA was also found to be up-regulated by root canal sealers ( P < .05). Taken together, the activation of gelatinases and t-PA might play an important role in the pathogenesis of root canal sealer–induced periapical inflammation.

Cytotoxicity of three resin-based root canal sealers: an in vitro evaluation.

The cytotoxicity of three resin-based root canal sealers (AH26, AH-Plus, Topseal) was evaluated in vitro. The experiments included two cell lines, L929 mouse skin fibroblasts and RPC-C2A rat pulp cells. The cytotoxicity was assessed by sulforodamine B (SRB) colorimetric assay and hemocytometer viable cell counting after 24- and 48-h exposure. AH26 had a severe cytotoxic effect whilst Topseal and AH-Plus showed a markedly lower toxic influence on the cells during the experimental period.

Toxicity evaluation of root canal sealers in vitro

To compare the toxicity of methacrylate resin-based root canal sealers with sealers based on epoxy resin and silicone by two-well established cell culture methods. Specimens of AH Plus, EndoREZ, RoekoSeal and Epiphany were prepared for direct contact in the Millipore filter diffusion test and as extracts in the MTT assay. Mouse fibroblasts (L929) were used as toxicity targets. Differences in cytotoxicity between fresh and set specimens and between the extracts of root canal sealers were determined by t-test (P < 0.05). In the filter diffusion test, freshly mixed Epiphany and AH Plus were rated severely toxic and RoekoSeal and EndoREZ nontoxic. When set, Epiphany was moderately toxic, whereas AH Plus, RoekoSeal and EndoREZ were nontoxic. Epiphany was significantly more toxic than RoekoSeal and EndoREZ (P < 0.05). In the MTT assay with set specimens, Epiphany was rated severely toxic; AH Plus and RoekoSeal slightly toxic; and EndoREZ nontoxic. Epiphany was significantly more toxic than the other three materials in this test (P < 0.001). The multi-methacrylate resin-based (Epiphany) root canal sealer was significantly more toxic to L-929 cells than the silicone-based Roeko Seal and the single methacrylate-based EndoREZ root canal sealers. AH Plus showed intermediate toxicity.

Water Sorption and Solubility of Methacrylate Resin–based Root Canal Sealers

The water sorption and solubility characteristics of three contemporary methacrylate resin-based endodontic sealers, EndoREZ, Epiphany, and InnoEndo, were compared with those obtained from Kerr EWT, Ketac-Endo (positive control), GuttaFlow, and AH Plus (both negative controls). Ten disks of each material were dehydrated in Drierite for 24 h and weighed to constant dry mass. They were placed in water and weighed periodically until maximum water sorption was obtained. The disks were dehydrated again to determine their mass loss (solubility) at equilibrium. Epiphany exhibited the highest apparent water sorption (8%) followed by Ketac-Endo (6.2%), InnoEndo (3.4%), EndoREZ (3.0%), AH Plus (1.1%), GuttaFlow (0.4%), and Kerr EWT (0.3%). Significantly higher solubility (3.5-4%) were observed for all three methacrylate resin-based sealers and Kerr EWT (3.95%), compared with Ketac-Endo (1.6%), AH Plus (0.16%), and GuttaFlow (0.13%). American Dental Association specifications require<3% solubility for endodontic sealers. Only Ketac-Endo, AH Plus, and GuttaFlow met that criterion.

Leakage of 4 resin-based root-canal sealers used with a single-cone technique

The aim of this study was to measure leakage of 4 resin-based sealers. Four groups of premolars (n = 60) were prepared using GT Rotary files and the crown-down technique and filled by the single-cone technique with AH26, AHPlus, EndoREZ, and an experimental MBP as sealer. Leakage was measured using the fluid filtration method after 15, 30, and 60 days and determined as microL/min(-1) x 10 psi. Statistical analysis by ANOVA and Tukey HSD test indicated that root fillings with AH Plus and the MBP showed lower leakage values after 15 days (P < .05). At 30 days, AH26 presented higher leakage values when compared to other sealers (P < .05). At 60 days, MBP and AH Plus presented the lower leakage values, differing significantly from EndoREZ (P < .05). It was observed that AH Plus and the experimental MBP showed lower leakage after 60 days than AH 26 and EndoREZ.

Clinical and Radiographical Evaluation of a Resin-based Root Canal Sealer: A 5-Year Follow-up

A retrospective clinical and radiographical analysis of 5-year postendodontic treatment with a resin-based sealer (EndoRez; Ultradent Products Inc, South Jordan, UT) and gutta-percha was conducted. The results after 14 to 24 months were reported previously. Of 180 patients, 120 responded to the 5-year recall. Success of root canal treatments was based on absence of clinical symptoms, a normal or slightly widened periodontal ligament, and absence or reduction of periapical radiolucencies in patients who had preexisting lesions. Root canals had been adequately filled to the working length in 92 teeth (76.66%) and short in 13 (10.83%). Fifteen cases (12.50%), filled flush at the initiation of the experiment, showed slight resorption of the filling material at the apex within the lumen of the root canal. Of the 10 roots with extrusion, none had radiographic evidence of sealer in the periradicular tissues after 5 years. All patients were free of clinical symptoms. Four cases (3.3%) showed partial healing, whereas 8 cases (6.66%) were judged failures. A life table analysis revealed a cumulative probability of success of 86.3% at the 5-year recall with a 95% confidence interval of 79.7 to 91.0. The clinical and radiographical data suggest that the tested resin-based sealer used in conjunction with gutta-percha performed very well as a root canal sealer over a period of up to 5 years.

In vitro biological adverse effects of dental resin monomers and endodontic root canal sealers

UDMA, a dental resin monomer, was analyzed for its capacity to induce oxidative stress and apoptosis. UDMA exhibited a dose-dependent cytotoxicity, and the cytotoxic effect was significantly decreased by co-treatment with N -acetylcystein (NAC), an antioxidant, suggesting involvement of oxidative stress in cell death caused by UDMA. The preventive effects of NAC were also observed in UDMA-induced apoptosis in RPC-C2A pulp like cell line. A fragmented DNA ladder pattern, characteristic of apoptosis, was shown by treatment with UDMA, but NAC blocked the DNA fragmentation. The preventive effects of NAC on apoptosis were also confirmed by Annexin V staining. In conclusion, UDMA likely induces apoptotic cell death via oxidative stress. By applying the same analysis, AH26, a resin-based root canal sealer, was found to cause oxidative stress and apoptosis. NAC lowered cytotoxicity and DNA fragmentation of AH26, suggesting that oxidative stress is involved in apoptotic cell death caused by AH26.

Evaluation of the radiopacity and cytotoxicity of resinous root canal sealers

The aim of this study was to evaluate the radiopacity and cytotoxicity of three resin-based (AH 26, EZ fill and AD Seal), a zinc oxide-eugenol-based (ZOB Seal), and a calcium hydroxide-based (Sealapex) root canal sealers. Specimens, 10 mm in diameter and 1 mm in thickness, were radiographed simultaneously with an aluminum step wedge using occlusal films, according to ISO 6876/2001 standards. Radiographs were digitized, and the radiopacity of sealers was compared to the different thicknesses of the aluminum step wedge, using the Scion image software. Using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, the cytotoxicity of each material was determined in immortalized human periodontal ligament (IPDL) cells. The results demonstrated that EZ fill was the most radiopaque sealer, while Sealapex was the least radiopaque (p 0.05). These results indicate that resin-based root canal sealer is more biocompatible and has advantage in terms of radiopacity.

In vitro evaluation of cytotoxicity of resin-based root canal sealers

<i>In vitro</i> evaluation of cytotoxicity of resin-based root canal sealers

Evaluation of apical microleakage of teeth sealed with four different root canal sealers

Objectives:to compare the apical sealing ability of four root canal sealers. Materials and methods: forty extracted human maxillary canines were instrumented 1 mm short of the anatomical apex and randomly assigned to four groups (n=10), according to the root canal sealer used for obturation: Endofill, AH Plus, EndoREZ and Epiphany. Root canals were obturated with guttapercha points, except for the Epiphany group, in which resin points (Resilon) were used. The teeth were immersed in India ink for seven days and clarified using methyl salicylate. The extent of apical dye penetration was measured with a measuroscope in all aspects of the canal.Results:AH Plus (0.02 mm ± 0.07), Epiphany (0.00 mm ± 0.00) and EndoREZ (0.32 mm ± 0.62) did not differ statistically to each other (p>0.01). EndoFill presented the highest dye penetration mean (0.83 mm ± 0.73) and was statistically different from the other sealers (p<0.01).Conclusions:the resin-based root canal sealers presented lesser apical microleakage than the zinc oxide and eugenol based sealer. No statistical differences were observed among resin based sealers.

Induction of heme oxygenase‐1 expression by root canal sealers in human gingival fibroblasts is augmented by oxidative stress

Heme oxygenase-1 (HO-1) is known as a stress-inducible protein and functions as an antioxidant enzyme. It has been shown that HO-1 is induced rapidly by a variety of chemical and physical stimuli. However, little is known about the induction of cellular signaling events after cell exposure to root canal sealers. The aim of this study was to investigate the effects of zinc oxide-eugenol-based root canal sealer N2 and epoxy resin-based root canal sealer Topseal on the expression of HO-1 protein in cultured human gingival fibroblasts (HGFs). The results showed that both N2 and Topseal were cytotoxic to HGFs in a concentration-dependent manner (p < 0.05). The exposure of quiescent HGFs to N2 and Topseal resulted in the induction of HO-1 protein expression in a time-dependent manner (p < 0.05). Furthermore, to determine whether oxidative stress could modulate HO-1 expression in HGFs by root canal sealers, HGFs were pretreated with glutathione (GSH) synthesis precursor 2-oxothiazolidine-4-carboxylic acid (OTZ) and GSH synthesis inhibitor buthionine sulfoximine (BSO) for 24 h. The pretreatment with OTZ decreased the N2-induced HO-1 protein level by approximately 32% (p < 0.05). However, BSO enhanced the N2-induced HO-1 protein level by up to twofold (p < 0.05). Similar results were found by Topseal. The pretreatment with OTZ decreased the Topseal-induced HO-1 protein level by approximately 12% (p < 0.05). However, BSO enhanced the Topseal-induced HO-1 protein level by up to 1.7-fold (p < 0.05). Taken together, HO-1 expression might be one signal transduction pathway linked to the induction of stress-inducible protein by root canal sealers. In addition, the activation of HO-1 is augmented by oxidative stress. Factors that induce GSH synthesis may appear useful in preventing oxidative damage mediated by root canal sealers.

Sealing properties of different resin‐based root canal sealers

In this study, a comparison of the sealing properties of three different resin-based sealers, AH26, Diaket, and EndoREZ with those of the root canal sealer zinc oxide-eugenol-based U/P Root Canal Sealer was performed. Eighty extracted single-rooted human mandibular first premolar teeth were used. The coronal part of each tooth was removed at the apical 17-mm of roots. The root canals were prepared to a size 7 with ProFile 0.06 taper Series 29 rotary instruments in a crown-down manner before lateral condensation of gutta-percha with the tested sealers (n = 20). A fluid filtration method was used for quantitative evaluation of apical leakage. Statistical analysis revealed that there were no significant differences between the resin-based sealers groups (AH26, Diaket, and EndoREZ) (p > 0.05). U/P Root Canal Sealer, zinc oxide-eugenol-based sealer, leaked significantly more than other tested groups (p < 0.05). Under the limitations of this study, resin-based root canal sealers were found more effective in sealing root canals than the zinc oxide-eugenol-based sealer.

Evaluation of apical sealing ability and adaptation to dentine of two resin‐based sealers

The purpose of this study was to evaluate the apical sealing ability and adaptation to dentine of two resin-based root canal sealers. The root canals of 55 human maxillary anterior teeth were prepared using a step-back technique and the smear layer removed with 17% ethylenediaminetetraacetic acid. The teeth were divided into two groups of 25 teeth and the remaining five teeth served as control. Then the teeth were prepared and obturated with gutta-percha by a lateral condensation and either AH plus and EndoRez used as a sealer. Twenty teeth from each group were used for the apical leakage test and the remaining five teeth from each group were used for examination under the scanning electron microscope (SEM). For apical leakage test, teeth were covered with nail varnish and sticky wax to within 1 mm of the apical foramen and placed in 2% methylene blue for 7 days. After this period, the teeth were sectioned longitudinally and apical leakage measurements made. The mean value of dye penetration for AH plus was 2.87 +/- 0.43 mm, while that of EndoRez was 4.54 +/- 0.36 mm. The difference between mean of dye penetration was statistically significant (P < 0.01). The SEM examination showed both sealers had better adaptation and penetration in coronal and middle thirds than apical third of root canal. In apical third, AH plus was adapted better adpated to dentine than EndoRez. In conclusion, AH plus sealer has better apical sealing ability and adaptation to dentine than EndoRez sealer.

Prevention of the epoxy resin-based root canal sealers-induced cyclooxygenase-2 expression and cytotoxicity of human osteoblastic cells by various antioxidants

Cyclooxygenase-2 (COX-2) is an inducible enzyme believed to be responsible for prostaglandin synthesis at the site of inflammation. Recently, the activation of COX-2 expression may be one of the important pathogenesis of root canal sealers-induced periapical inflammation. However, little is known about whether chemical interaction can modulate the epoxy resin-based root canal sealers-induced cytotoxicity as well as COX-2 expression. The aim of the present study was to investigate the effects of antioxidants catalase, superoxide dismutase (SOD), and N-acetyl-L-cysteine (NAC) on AH26- and Topseal-induced COX-2 mRNA gene and cytotoxicity in human osteoblastic cell line U2OS cells. The results showed that both epoxy resin-based root canal sealers were cytotoxic to U2OS cells in a concentration-dependent manner (p<0.05). AH26 and Topseal were found to induce COX-2 mRNA gene expression in U2OS cells. The addition of glutathione (GSH) precursor NAC led to decrease the induction of COX-2 mRNA gene expression and cytotoxicity by both AH26 and Topseal (p<0.05). However, catalase and SOD lacked the ability to prevent AH26-and Topseal-induced cytotoxicity and COX-2 mRNA gene expression (p>0.05). Taken together, the activation of COX-2 mRNA gene expression may be one of the pathogenesis of epoxy resin-based root canal sealers-induced periapical inflammation. In addition, GSH depletion, but not the attack of oxygen free radicals, could be the mechanism for epoxy resin-based root canal sealers-induced cytotoxicity and COX-2 mRNA gene expression. Factors that induce GSH synthesis may appear useful in preventing cell damage mediated by epoxy resin-based root canal sealers.