Induction of Interleukin-6 and Interleukin-8 Gene Expression by Root Canal Sealers in Human Osteoblastic Cells

Inflammatory response to epoxy resin and calcium silicate sealers preheated with different temperatures: an in vivo study

OBJECTIVE

To determine the impact of heat exposure of different sealers on inflammatory cytokine secretions and tissue response in vivo.

MATERIALS AND METHODS

Silicone tubes were prefilled with epoxy resin (ER) or calcium silicate (CS) sealers, preheated at 37, 60, or 120 °C, and implanted in rat subcutaneous site. Peri-implant exudate and tissue were analyzed after 1 and 4 weeks for cytokine secretions and tissue organization.

RESULTS

At 1 week, 120 °C-preheated CS and ER induced higher secretions of tumor necrosis factor alpha (TNF-α) and interleukin 6 (IL-6), respectively, as compared to sham/empty tube groups. At 4 weeks, whereas TNF-α secretion was reduced in CS, it increased in ER group, particularly for 120 °C. Both sealers revealed high IL-6 after 4 weeks as compared to sham/empty tube, and generally, higher IL-6 secretions were associated with ER. Histology at 1 week revealed lower degree of inflammatory infiltrate in the groups of the highest preheating temperature (120 °C). Nonetheless, at 4 weeks, whereas fibrous capsule area and inflammatory infiltrate remained low in the CS120 group, they were high in ER120.

CONCLUSION

Preheating ER sealer to 120 °C induced high and prolonged secretion of proinflammatory cytokines (TNF-α and IL-6), whereas this effect was transient for the CS sealer. This was associated with increased fibrous capsule and inflammatory infiltrate in response to 120 °C-preheated ER.

CLINICAL RELEVANCE

Heat-induced changes in sealer properties alter the inflammatory response in vivo, which may affect the clinical outcome. This will not only help appropriate selection of obturation technique for different sealers, but also for optimizing the properties of new generation of sealers.

IL-1ß, IL-6 and TNF-α expression levels of macrophage cells induced by benzydamine hydrochloride, benzydamine hydrochloride with chitosan, calcium hydroxide and chlorhexidine medicaments: An ELISA study

The aim of the present study was to evaluate IL-1ß, IL-6 and TNF-α expression levels of macrophage cells induced by benzydamine hydrochloride (BNZ), BNZ with chitosan, calcium hydroxide (CH) and chlorhexidine (CHX) medicaments. Half maximal inhibitory concentrations (IC₅₀) were assessed on THP-1, Saos-2, and CRL-2014 cells using MTT assay. THP-1 cells were differentiated into macrophages with phorbol12-myristate13-acetate and activated with lipopolysaccharide. IL-1β, IL-6 and TNF-α levels in supernatants were determined using enzyme-linked immunosorbent assay (ELISA). The data were examined with one-way ANOVA and Tukey's multiple comparison test (p=0.05). At the selected concentrations, the cell viability was higher than 50% for chitosan and CH, whereas CHX presented lower IC₅₀ values than BNZ and BNZ+chitosan. According to ELISA results, the lowest IL-1β, IL-6 and TNF-α values were observed with BNZ+Chitosan 50 µg/mL and BNZ 50 µg/mL. BNZ+chitosan 50 µg/mL combination has revealed promising anti-inflammatory effects. Nevertheless, these findings need to be examined in clinical conditions.

Endodontic set sealer eluates promote cytokine production in human mononuclear and periodontal ligament cells

Endodontic freshly mixed sealers display toxic effects; however, these are significantly reduced and most become relatively inert in the set state but there is no information about the possible inflammatory reaction promoted by them. Four contemporary and different formulated endodontic set sealers (MTA Fillapex, BioRoot RCS, AH Plus, and Pulp Canal Sealer) were evaluated. Human periodontal ligament cells and human peripheral blood mononuclear cells were stimulated for 3, 6, 12 and 24 h. Interleukin-6, tumour necrosis factor-alpha, interleukin-8 and interleukin-10 concentrations were measured by enzyme-linked immunosorbent assay. All endodontic set sealer eluates promoted a similar production (P ˃ 0.05) of the four cytokines. However, their concentrations decreased within a short time period to nearly undetectable concentrations after 24 h, suggesting that the studied endodontic set sealers do not possess inflammatory properties which has favoured their long-term use in clinical practice.

Toxic mechanisms of Roth801, Canals, microparticles and nanoparticles of ZnO on MG-63 osteoblasts

ZnO eugenol-based materials are widely used for restoration of caries cavity, apical retrograde filling and root canal sealer. Their effects on apical bone healing await investigation. The toxic mechanisms of ZnO particles and nanoparticles to MG-63 osteoblastic cells were studied. We found the different morphology and size of various particles as observed by scanning electron microscope. Particles of Canals and Roth801 were larger than ZnO-205532 microparticles and ZnO-677450 nanoparticles. Four ZnO particles showed cytotoxicity (>25 μg/ml) as analyzed by MTT. Transmission electron microscope found intracellular vacuoles with particle content. Exposure to ZnO particles induced ROS production and cell cycle arrest as studied by DCF and propidium iodide flow cytometry. ZnO particles activated ATM, ATR, Chk1, Chk2, γ-H2AX, ERK and p38 phosphorylation as detected by immunofluorescent staining and western blotting. The protein expression of cdc2, cyclin B1 and cdc25C were decreased, whereas GADD45α and hemeoxygenase-1 (HO-1) were stimulated. ZnO particles' cytotoxicity to MG63 cells was prevented by N-acetylcysteine (NAC), but not CGK733, AZD7762, U0126 and SB203580. ZnO showed little effect on IL-8 and sICAM-1 secretion. These results indicated that ZnO particles are toxic to osteoblasts. ZnO particles' toxicity were related to ROS, and DNA damage responses, checkpoint kinases, cell cycle arrest, ERK and p38 signaling, but not IL-8 and ICAM-1. These results were useful for materials' development and promote apical healing. Dentists should avoid of extruding ZnO-based sealers excessively over root apex and prevent residual ZnO-based retrograde filling materials in apical area during endodontic practice.

Comparative Evaluation of Physicochemical Properties and Apical Sealing Ability of a Resin Sealer Modified with Pachymic Acid

Objective:

The addition of pachymic acid (PA) to AH Plus (an epoxy resin sealer) offsets the cytotoxicity of the latter. Prior to the clinical implementation of this formulation, a thorough knowledge of its physicochemical properties and sealing ability becomes mandatory. Hence, this in vitro study aimed to characterize and evaluate the physicochemical properties and apical sealing ability of AH Plus (AHP) with and without the addition of PA.

Methods:

Flow, setting time, film thickness, solubility and radiopacity of AHP (group 1) and AHP modified with PA (AHP/PA, group 2) were evaluated in accordance with the guidelines put forth by ISO 6876:2012. The percentage was determined under each parameter. Apical sealing ability was assessed using fluid filtration device. An independent samples t-test was used for inter- and intra-group comparisons of mean fluid flow (MFF).

Results:

Incorporating PA to AHP decreased its flow, setting time and film thickness by 24.34%, 2.14% and 31.71% respectively. The solubility of group 2 increased on day 1 by 85.71% and decreased on days 3, 7 and 14 by 46.67%, 34.79% and 13.8% respectively. The radiopacity of AHP was not altered by the addition of PA. MFF rates of group 2 was significantly higher than group 1 on day 1, but not significantly different on day 7.

Conclusion:

AHP/PA exhibited physicochemical properties that were within the requirements of ISO and with time, and showed fluid flow similar to AHP.

EZH2 regulates dental pulp inflammation by direct effect on inflammatory factors

OBJECTIVE

Pulpitis is a multi-factorial disease that could be caused by complex interactions between genetics, epigenetics and environmental factors. We aimed to evaluate the role of Enhancer of Zeste Homolog 2 (EZH2) in the inflammatory response of human dental pulp cells (HDPCs) and dental pulp tissues.

METHODS

The expressions of inflammatory cytokines in HDPCs treated by EZH2 complex or EZH2 siRNA with or without rhTNF-α were examined by quantitative real-time polymerase chain reaction (q-PCR). The levels of secreted inflammatory cytokines including IL-6, IL-8, IL-15, CCL2 and CXCL12 in culture supernatants were measured by Luminex assay. In rat pulpitis model, the effects of EZH2 on dental pulp tissues were verified by histology. We invested the mechanisms of the effect of EZH2 on the inflammatory factors by ChIP assay.

RESULTS

EZH2 down-regulation inhibited the expression of inflammatory factors, including IL-6, IL-8, IL-15, CCL2 and CXCL12 in HDPCs. EZH2 complex promoted the expression and secretion of these inflammatory factors in HDPCs, while EZH2 silencing could attenuate the promotion of inflammatory factors that were induced by rhTNF-α. In pulpitis models of rats, EZH2 down-regulation inhibited the inflammatory process of dental pulp while EZH2 complex showed no significant facilitation of pulpal inflammation. In addition, EZH2 could bind on the promoters of IL-6, IL-8 and CCL2, but not IL-15 and CXCL12, to affect the transcription of these proinflammatory cytokines.

CONCLUSIONS

In HDPCs, EZH2 could induce inflammation, while EZH2 down-regulation could attenuate the inflammatory responses. EZH2 plays an important role in this inflammatory process of dental pulp.

Cytotoxicity and biocompatibility of Zirconia (Y-TZP) posts with various dental cements

Objectives

Endodontically treated teeth with insufficient tooth structure are often restored with esthetic restorations. This study evaluated the cytotoxicity and biological effects of yttria partially stabilized zirconia (Y-TZP) blocks in combination with several dental cements.

Materials and Methods

Pairs of zirconia cylinders with medium alone or cemented with three types of dental cement including RelyX U200 (3M ESPE), FujiCEM 2 (GC), and Panavia F 2.0 (Kuraray) were incubated in medium for 14 days. The cytotoxicity of each supernatant was determined using 3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays on L929 fibroblasts and MC3T3-E1 osteoblasts. The levels of interleukin-6 (IL-6) mRNA were evaluated by reverse transcription polymerase chain reaction (RT-PCR), and IL-6 protein was evaluated by enzyme-linked immunosorbent assays (ELISA). The data were analyzed using one-way ANOVA and Tukey post-hoc tests. A p < 0.05 was considered statistically significant.

Results

The MTT assays showed that MC3T3-E1 osteoblasts were more susceptible to dental cements than L929 fibroblasts. The resin based dental cements increased IL-6 expression in L929 cells, but reduced IL-6 expression in MC3T3-E1 cells.

Conclusions

Zirconia alone or blocks cemented with dental cement showed acceptable biocompatibilities. The results showed resin-modified glass-ionomer based cement less produced inflammatory cytokines than other self-adhesive resin-based cements. Furthermore, osteoblasts were more susceptible than fibroblasts to the biological effects of dental cement.

Biocompatibility of a new epoxy resin-based root canal sealer in subcutaneous tissue of rat

Objective:

The objective was to evaluate the subcutaneous biocompatibility of two root canal sealers.

Materials and Methods:

Thirty female rats were distributed into two groups of 15 animals. Each received subcutaneous dorsal implants: Silicone tubes filled with AH Plus or Obtuseal. After the 11^th, 14^th, and 45^th days, tissues were collected for biopsy and fixed and processed for histologic evaluation. Observations of the cellular inflammatory components, such as lymphocytes and macrophages, were made. The data were analyzed using Kruskal–Wallis and Connover tests (P < 0.05).

Results:

By the 7^th day, lymphocyte infiltration increased in both groups (P = 0.0104). However, macrophage infiltration increased only in the AH Plus group (P = 0.0011). By the 14^th and 45^th days, lymphocyte and macrophage infiltrations were reduced. At the end of the experimental period, no statistically significant differences were found between the AH Plus group and the Obtuseal group (P > 0.05).

Conclusion:

After 45 days, Obtuseal yielded a satisfactory tissue reaction; it was biocompatible when tested in subcutaneous rat tissue. On the basis of the obtained results, it was concluded that Obtuseal root canal sealer caused a satisfactory tissue reaction as AH plus, because it was biocompatible when tested in the subcutaneous tissue of rats.

Connective tissue reaction of rats to a new zinc-oxide-eugenol endodontic sealer

The aim of this study was to evaluate the biocompatibility in rat subcutaneous connective tissue of a new zinc oxide endodontic sealer (Endomethasone N) compared to those provided by Endofill and Sealer 26. Polyethylene tubes containing the test materials were implanted into dorsal subcutaneous connective tissue of Wistar albino rats. After 7 and 42 days, the implants with the surrounding tissue were collected, fixed, and processed for histologic evaluation. Sections were evaluated for the presence of inflammatory cells (poly or monomorfonuclear), blood vessels, necrosis area, and thickness of fibrous capsule. Comparisons between groups and time-periods were performed with Kruskal-Wallis and Mann-Whitney U non-parametric tests for 5% significance level. No differences in the biocompatibility patterns among the materials for the 2 experimental periods were observed. Independently of the sealer, the tissue behavior showed a tendency to decrease the irritation effect over time. It can be concluded that all sealers are irritant, but its toxicity decreased with time. Endomethásone N showed biocompatible characteristics comparable with those provided by Endofill and Sealer 26.

Behaviour of co-cultured human osteoclastic and osteoblastic cells exposed to endodontic sealers' extracts

OBJECTIVES

Bone tissue is constantly being moulded and shaped by the coordinated action of bone-resorbing osteoclasts and bone-synthesizing osteoblasts. This study addresses the long-term effects of endodontic sealers' extracts (AH Plus™, GuttaFlow™, Tubliseal™, Sealapex™ and RealSeal™) on co-cultures of human osteoclastic and osteoblastic cells.

METHODS

The sealers were mixed according to the manufacturer's instructions, freshly extracted with culture medium (1.3 cm(2)/ml; 24 h; 37 °C, 5% CO2/air) and diluted (1:20-1:2,500). Co-cultures of osteoclastic and osteoblastic cells, established from precursors present in human peripheral blood mononuclear cells and bone marrow cells, respectively, were exposed to the extracts for 21 days. Co-cultures were characterized for the osteoclastic and osteoblastic response.

RESULTS

The sealers caused a dose-dependent decrease on TRAP and ALP activities, respectively, an osteoclastic and an osteoblastic marker. The resorbing ability of the osteoclastic cells and the expression of osteoclastic and osteoblastic genes were also decreased; in addition, the extracts affected several intracellular signalling pathways. Inhibition was higher during the two first weeks, followed by adaptive cell responses. Osteoblastic response was more sensitive to the extracts' toxicity and showed lower adaptive ability.

SIGNIFICANCE

A correlation to the clinical situation cannot be predicted; however, the results suggest that the sealers' eluents might disrupt the highly regulated interaction between osteoblastic and osteoclastic cells, compromising the local bone metabolism. Also, the higher susceptibility of the osteoblastic response might be particularly relevant in the initial stages of the healing of periapical lesions, due to the significant role of the bone formation events.

PPARγ inhibits inflammation and RANKL expression in epoxy resin-based sealer-induced osteoblast precursor cells E1 cells

OBJECTIVES

The AH26 of epoxy resin-based sealer is used widely owing to its excellent physical characteristics but it induces oxidative stress and cytotoxicity at the periapical tissues. AH26 exhibited cytotoxicity towards MC-3T3-E1 cells, which resulted in mitochondria-mediated apoptosis. Peroxisome proliferator-activated receptor (PPARγ) has an anti-inflammatory effect in several tissue and cells, but its action of AH26-related inflammation is not completely understood. The aim of this study is to investigate the anti-inflammatory and anti-osteoclastic mechanisms of PPARγ in AH26-induced MC-3T3 E1 cells.

METHODS

AH26 was prepared according to the manufacturer's instructions. The 1-day extraction sample, which was diluted by 30%, was tested in this experiment. Recombinant deficiency adenoviral PPARγ (Ad/PPARγ) was used to examine PPARγ over-expression in MC-3T3 E1 cells. AH26-induced reactive oxygen species (ROS) formation was analysed using 2',7'-dichlorodihydrofluorescein diacetate (DCFH-DA) with fluorescence-activated cell sorting (FACS), and the expression of receptor activator of nuclear factor-κB ligand (RANKL) and inflammatory molecules was determined by immunoblotting. The anti-inflammatory and anti-osteoclastic mechanisms of the PPARγ-involved signal pathway was examined by immunoblotting.

RESULTS

The AH26 elutes induced inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), RANKL expression and ROS formation. In addition, the AH26 elutes suppressed the expression of PPARγ. However, the recovery of PPARγ expression with Ad/PPARγ resulted in the inhibition of iNOS, COX-2, RANKL and ROS formation despite the AH26 treatment in MC-3T3 E1 cells. The mechanism of PPARγ was confirmed by the blocking of nuclear factor kappa B (NF-κB) translocation to the nucleus after the suppression of ERK1/2, SAPK/JNK and AP-1 in AH26-induced MC-3T3 E1 cells.

CONCLUSION

From this result, PPARγ acts to inhibit bone destruction in AH26-induced bone cells. Therefore, the anti-inflammatory and anti-osteoclastic character of PPARγ might be applicable for healing periapical lesions more rapidly or reducing the induction of cellular inflammation caused by some endodontic sealers.

N-acetyl cysteine alleviates cytotoxicity of bone substitute

Lack of cytocompatibility in bone substitutes impairs healing in surrounding bone. Adverse biological events around biomaterials may be associated with oxidative stress. We hypothesized that a clinically used inorganic bone substitute is cytotoxic to osteoblasts due to oxidative stress and that N-acetyl cysteine (NAC), an antioxidant amino acid derivative, would detoxify such material. Only 20% of rat calvaria osteoblasts were viable when cultured on commercial deproteinized bovine bone particles for 24 hr, whereas this percentage doubled on bone substitute containing NAC. Intracellular ROS levels markedly increased on and under bone substitutes, which were reduced by prior addition of NAC to materials. NAC restored suppressed alkaline phosphatase activity in the bone substitute. Proinflammatory cytokine levels from human osteoblasts on the bone substitute decreased by one-third or more with addition of NAC. NAC alleviated cytotoxicity of the bone substitute to osteoblastic viability and function, implying enhanced bone regeneration around NAC-treated inorganic biomaterials.

Inflammatory suppression by endodontic sealers after aging 12 weeks In vitro

Dental endodontic sealers are in intimate contact with tissues around the root apex (periapical area) for extended periods. New endodontic sealers have been developed in the past decade, but the biological responses to many new products are not well documented. In this study, we assessed in vitro monocytic cytotoxic and inflammatory responses to several contemporary endodontic sealers. AH-Plus (AH), Pulp Canal Sealer (PC), Epiphany (EPH), Endo-Rez (ER), and an experimental Endo-Rez (ERx) were initially placed in buffered-saline for 12 weeks to simulate in vivo use. After "aging," specimens were placed in direct contact with THP1 monocytes for 72 h and their cytotoxicity (mitochondrial response; MTT) or ability to trigger or suppress cytokine secretion (ELISA; TNFalpha, IL1beta, IL=6; +/- lipopolysaccharide (LPS) exposure) were measured relative to Teflon (Tf) negative controls. Cellular responses among conditions were compared with ANOVA and Tukey post-hoc analysis (alpha = 0.05). Two of the five sealers, EPH and PC, still suppressed cell mitochondrial activity by 70% or more after 12 weeks of conditioning in saline. No sealer alone activated monocytic TNFalpha, IL1beta, or IL6 secretion (p > 0.05 vs. +LPS controls). When THP1 were activated by LPS after exposure to the sealers, differential suppression of TNFalpha, IL1beta, and IL6 secretion was observed for two of the five sealers tested. (EPH and PC) This data suggest that common endodontic sealers do not activate monocytic TNFalpha, IL1beta, and IL6 secretion in vitro by themselves, but degradation products of the sealers may suppress activation of monocytes.

Histopathologic study of rat connective tissue responses to maxillofacial silicone elastomers

The aim of this histopathologic study was to assess and compare the subcutaneous connective tissue reaction to three different maxillofacial silicone elastomers (Cosmesil, Multisil, Episil). The test materials were directly inserted subcutaneously into the dorsal subcutaneous tissue of Wistar albino rats. Histopathological examinations were done at 7, 30, and 90 days after the implantation procedure. The presence of inflammation, presence of inflammatory giant cells, and the thickness of fibrous connective tissue adjacent to each inserted sample were recorded. Data was evaluated by analysis of variance, Wilcoxon signed ranks test and Kruskal Wallis test. Cosmesil, Multisil and Episil silicone elastomers at 7 days elicited a severe inflammatory reaction. However, these reactions decreased by the 30 and 90 days. All silicone elastomers elicited a moderate inflammatory reaction at 30 and 90 days. There were no significant differences in tissue reaction between the materials at 7, 30, and 90 days (P > 0.05). All the maxillofacial silicone elastomers evaluated can not be assigned a favorable biocompatibility level based on this study's histologic findings.

Bioactive materials in endodontics

Endodontic treatment in dentistry is a delicate procedure and many treatment attempts fail. Despite constant development of new root canal filling techniques, the clinician is confronted with both a complex root canal system and the use of filling materials that are harmful for periapical tissues. This paper evaluates reported studies on biomaterials used in endodontics, including calcium hydroxide, mineral trioxide aggregate, calcium phosphate ceramics and calcium phosphate cements. Special emphasis is made on promising new biomaterials, such as injectable bone substitute and injectable calcium phosphate cements. These materials, which combine biocompatibility, bioactivity and rheological properties, could be good alternatives in endodontics as root canal fillers. They could also be used as drug-delivery vehicles (e.g., for antibiotics and growth factors) or as scaffolds in pulp tissue engineering.

In vivo comparison of the biocompatibility of two root canal sealers implanted into the subcutaneous connective tissue of rats

OBJECTIVE

To evaluate the subcutaneous biocompatibility of 2 root canal sealers.

STUDY DESIGN

The subcutaneous implant technique recommended by the Fédération Dentaire International (FDI) was used to test Endométhasone and EndoREZ root canal sealers. These materials were placed in Teflon tubes, 1 mm in diameter and 10 mm in length, and implanted into 2 pockets created in the back of 40 Calomys callosus rodents, 20 for each material. Tissue biopsies were collected and histologically examined 15, 30, 60, and 90 days after the implantation procedure. The overall level of the inflammatory tissue response was graded as none, slight, moderate, or severe on the sealer-connective tissue interface at the opening ends of the tubes. The connective tissue response along the lateral wall outside of each tube served as a negative control.

RESULTS

The tissue reaction to the Endométhasone diminished with time. The EndoREZ sealer was highly toxic during all experimental periods.

CONCLUSION

Endométhasone root canal sealer presented biocompatibility within the analyzed periods, whereas EndoREZ showed no biocompatible behavior and caused late hypersensitive reaction.

The role of cyclooxygenase-2 (COX-2) in inflammatory bone resorption

Prostaglandin E2 (PGE(2)) is an important inflammatory mediator that plays an essential role in the development and progression of periradicular diseases. Cyclooxygenase-2 (COX-2) is the inducible enzyme responsible for increased PGE(2) levels during inflammation and other pathologic processes. The purpose of this study was to determine the role of COX-2-mediated PGE(2) synthesis in osteoclast formation in response to endodontic pathogens and materials. Primary osteoblast cultures and osteoclast cultures were prepared from COX-2 knockout (K/O) and wild-type (WT) littermates. These cultured cells were exposed to lipopolysaccharide (LPS) or root canal obturation materials including gutta-percha (GP), Resilon (RS), mineral trioxide aggregates (MTAs), and AH Plus (AH+). Osteoclast formation was evaluated using tartrate-resistant acid phosphatase (TRAP) staining. The expression of receptor activator of NF-kappaB ligand (RANKL) and osteoprotegerin (OPG) was determined by real-time polymerase chain reaction (PCR) analysis. It was found that in both WT and K/O cultures, treatment with LPS led to a marked increase in osteoclast formation. The number of osteoclasts formed was significantly lower in K/O cultures compared to WT cultures. Exposure to endodontic materials did not lead to any significant osteoclast formation. LPS and endodontic materials caused a decrease in both RANKL and OPG expression in WT cells. In K/O cells, the baseline levels of RANKL and OPG expression were dramatically decreased compared to the WT cells. In conclusion, COX-2-mediated PGE(2) expression is required for LPS-induced inflammatory bone resorption and maintaining the baseline level of RANKL and OPG expression. LPS-induced osteoclast formation may be independent of the RANKL pathway.

Initial In Vitro Biological Response to Contemporary Endodontic Sealers

The objective of this study was to evaluate the cytotoxicity of three endodontic sealers (AH Plus/Maillefer-Dentsply, Epiphany/Pentron, GuttaFlow, Coltene-Whaledent). Materials were mixed according to the manufacturer instructions and packed into Teflon molds (10 x 1 mm). For cytotoxicity testing (MTT method), the specimens were placed in contact with cultured cells, then evaluated at two subsequent time points (24 or 72 h). In addition to testing the mixed materials, 5 microl of primer liquid (GuttaFlow and Epiphany) and resin solvents (HEMA, ethanol, sterile water, or acetone) were added directly in culture for 24 and 72 h. The results showed that most materials pose significant cytotoxic risks and that cytotoxicity generally increased with time. At 72 h, GuttaFlow became significantly less toxic than AH Plus, Epiphany sealer, and Resilon. The current results support the need to continue to develop better endodontic sealers that combine the excellent sealing and bonding properties of resins with acceptable biological properties for endodontic applications.

Comparison of the Intraosseous Biocompatibility of AH Plus, EndoREZ, and Epiphany Root Canal Sealers

To evaluate the intraosseous biocompatibility of AH Plus, EndoREZ, and Epiphany root canal sealers as recommended by the Technical Report #9 of the Fédération Dentaire Internationale (FDI). Thirty guinea pigs, 10 for each material, divided into experimental periods of 4 and 12 weeks, received one implant on each side of the lower jaw symphysis. At the end of the observation periods, the animals were killed and the specimens prepared for routine histological examination. After analyzing both periods, the inflammatory tissue reaction to EndoREZ was considered severe. In the AH Plus group, the reaction changed from severe to moderate, while it was observed biological compatibility to Epiphany with bone formation and none to slight inflammatory reaction. It was concluded that Epiphany root canal sealer was the only material that presented intraosseous biocompatibility within the two analyzed periods.