Cytotoxicity of Two Experimental Epoxy Resin-Based Sealers

Effect of an Experimental Resin-based Sealer (Resil) and AH-26 on Postoperative Pain: A Randomized Controlled Clinical Trial

Introduction

One of the most common problems in endodontic treatments is post-treatment pain, and sealers might be one of the factors influencing the degree of pain following root canal therapy. The purpose of this study is to compare pain following endodontic treatment using an AH-26 resin sealer against the Resil experimental sealer in mandibular molars with irreversible pulpitis.

Materials and Methods

One hundred patients with irreversible pulpitis in the mandibular first or second molar were randomly divided into two groups (n=50) based on the type of sealer applied. Two postgraduate students with at least five years of experience treated all patients. All patients had a single root canal treatment. Postoperative pain scores and analgesic consumption were assessed after 6, 12, 24, and 48 hours and 3, 4, 5, 6, and 7 days after the treatment. The data were statistically analyzed by Fisher's exact or Chi-Square test (to compare the distribution of qualitative variables in two groups), repeated measures ANOVA (to compare changes in pain intensity over time in two groups), Boneferronie (for pairwise comparisons), Friedman, Wilcoxon and Mann-Whitney tests (for assessment of the changes in pain scores over time). The generalized estimating equations (GEE) were used for assessing time and group effects.

Results

There was no significant difference in postoperative pain between groups at any of the time points studied (P>0.05), and also for patient analgesic consumption between groups (P>0.05). Both groups recorded the maximum pain levels in the first 6 hours. For each subsequent day postoperatively, the odds ratio (OR) of not using analgesics was 2.078.

Conclusion

Resil and AH-26 perform similarly in terms of the occurrence and intensity of postoperative pain in mandibular molar teeth with irreversible pulpitis.

Preparation of Bismuth Tungstate Nanomaterials with Different Morphologies and Their Effect on Exercise Rehabilitation of Patients with Lumbar Disc Herniation

It is understood that the effect of exercise rehabilitation drugs in patients with lumbar disc herniation is poor. Some studies have shown that bismuth tungstate nanomaterials with certain morphology can treat the exercise rehabilitation of patients with lumbar disc herniation. In order to help patients with lumbar disc herniation to a certain extent, in this paper, bismuth tungstate nanomaterials with different structures and morphologies were prepared by hydrothermal method, and viscous tungsten nanomaterials with different structures and morphologies were prepared by adjusting the pH value of the solution and the concentration of CTAB. In this paper, the structure and morphology of tungsten samples with different structure and morphology were characterized by CTAB X-ray (XRD) deflection and FESEM. It was found that the morphology of the samples changed after adding 0.02 mol/L surfactant CTAB in the reaction system, and when the concentration of CTAB was 0.04 mol/L, the nanotubes were stacked together under the action of surfactant. When the concentration of CTAB increased to 0.06 mol/L, the self-assembled nanocomposites tended to be petal like.

Biocompatibility of an experimental endodontic sealer (Resil) in comparison with AH26 and AH-Plus in rats: An animal study

Background. This experimental study sought to assess the biocompatibility of Resil, an experimental epoxy resin-based sealer, in comparison with AH26 and AH-Plus sealers in rats. Methods. Twelve male Wistar rats weighing 400 to 500 grams were evaluated in this experimental study. Four polyethylene tubes containing Resil, AH-Plus, AH26 sealers, and an empty tube were implanted subcutaneously in rats. The degree of inflammation, type of inflammatory cells present, foreign body reaction, quality of connective tissue, and presence of fibrotic capsule were evaluated histopathologically at 7 and 30 days after implanting the tubes to assess the biocompatibility of sealers. Data were analyzed using the Chi-square test. Results. At 7 days, the degree of inflammation in Resil group was almost similar to AH26 group, and 66.7% of rats showed moderate inflammation. AH-Plus group showed less inflammation than Resil and AH26 (50% of rats showed low degree of inflammation), At 30 days, the inflammatory status of all groups was the same, and 83.3% of rats showed very low degree of inflammation. The inflammatory response during the experiment decreased from day 7 to day 30 in all groups. The neutrophil count (P=0.00), fibrotic capsule (P=0.01) and the amount of granulation tissue (P=0.05) significantly decreased from day 7 to day 30 in Resil group. Conclusion. Resil sealer showed appropriate biocompatibility at 7 and 30 days after subcutaneous implantation in rats, comparable to AH26 and AH-Plus. Clinical studies are required to confirm these results.

Final Endodontic Irrigation with 2% Peracetic Acid: Antimicrobial Activity and Cytotoxicity

OBJECTIVE

 The aim of present study was to assess the cytotoxicity and antimicrobial efficacy of 2% peracetic acid (PAA) compared with 5.25% sodium hypochlorite (NaOCl) and 2% chlorhexidine (CHX).

MATERIAL AND METHODS

 For the cytotoxicity test, 100 µl of the tested solutions were added in 12 wells with ECV 304 endothelial cells in each group: NaOCl, CHX, and PAA, in addition to the control group. Each solution was evaluated after 24 hours of contact in four dilutions: 0.2, 0.1, 0.05 and 0.025 through mitochondrial function using MTT colorimetric assay. In the antimicrobial evaluation, 40 dentin blocks 5 mm in length and 0.2 g in weight were incubated with 400 µl of Enterococcus faecalis suspension for 21 days at 37°C. The contaminated samples were divided into three experimental groups within 5 minutes of contact: NaOCl group, CHX group, PAA group, as well as the positive control group. The specimens received treatment and were transferred to a tube with saline for serial dilution of the solution and seeding for isolation and colony forming unit (CFU) count.

STATISTICAL ANALYSIS

 The results obtained were expressed as mean (A570 nm) ± standard deviation (SD) and in a multiple linear regression model and multiple comparisons conducted.

RESULTS

 The antimicrobial evaluation revealed that the NaOCl and CHX groups showed a statistically significant difference compared with the control group (p < 0.001), while the PAA reduced only the CFU growth. It can be concluded that, among the agents tested, PAA expressed greater cell viability, followed by CHX and NaOCl. However, it did not show greater antimicrobial activity in vitro in the mature biofilm of Enterococcus faecalis.

Cytotoxicity and Oxidative Stress Induction by Root Canal Sealers in Human Periodontal Ligament Fibroblasts: An in vitro Study

Introduction

The aim of the study was to investigate the in vitro cytotoxicity, the profile of cell death, and the level of oxidative stress in human periodontal ligament fibroblasts (HPdLFs) after exposure to selected root canal sealers.

Methods and Materials

Freshly mixed or set Endomethasone N (EN), RealSeal (RSEAL), Roeko Seal Automix (RSA), and Sealapex (SP) were incubated with HPdLFs. Fluorescein isothiocyanate (FITC)-annexin V (AnV) and propidium iodide (PI) staining followed by flow cytometry was used to identify the effects of the materials on cell viability and the profile of cell death. 2,7-dichlorodihydrofluorescein diacetate (DCFH-DA) with fluorescence-activated cell sorting was used to determine reactive oxygen species (ROS) formation in HPdLFs. Statistical analyses were performed using one-way ANOVA followed by post hoc tests, and significance was determined at P<0.05.

Results

All materials reduced the viability of the cultured cells compared with the controls (P<0.05). Fresh SP and EN, and set RSA generated an increase of necrotic cells (P<0.05), whilst fresh RSEAL and RSA induced an elevation of apoptotic cells (P<0.001). Set RSEAL caused a rise in both apoptotic and necrotic cells compared with the controls (P<0.05). Fresh EN, RSEAL, and SP resulted in increased intracellular ROS generation compared with the negative control (P<0.001), whilst fresh RSA and all set materials were ineffective.

Conclusions

This in vitro study showed us the materials tested were characterized by differentiated cytotoxic effects on HPdLFs. The fresh and set forms of sealers were capable of eliciting toxic action, inducing apoptosis and/or necrosis in HPdLFs. The toxic effects of fresh EN, RSEAL, and SP might have been due to the induction of oxidative stress in human periodontal fibroblasts. The cytotoxicity of RSA seemed to be related to the involvement of other mechanisms.

GuttaFlow® Bioseal Cytotoxicity Assessment: In Vitro Study

The sealers used for root canal treatment should be biocompatible for the peri-radicular tissues, to evaluate the cytotoxic effects of GuttaFlow® bioseal sealer and to compare them with AH26® epoxy resin. Culture media were conditioned with the GuttaFlow® bioseal and AH26® pellets. MDPC-23 odontoblast cell cultures were treated with conditioned medium and serial dilutions. To evaluate the metabolic activity and cellular viability, the MTT and SRB assays were performed. To determine the production of reactive oxygen species, the DHE and DCF-DA probes were used. Cell cycle and cell-death types were assessed by cytometry, and to evaluate the mineralization capacity, the Alizarin Red S coloration was used. Statistical analysis was performed using analysis of variance (ANOVA) when normality was found and Kruskal-Wallis on the opposite case. For the comparison with normality values, the Student t-test was used. Cells exposed to the GuttaFlow® bioseal conditioned medium maintained high metabolic activities, except at higher concentrations. Likewise, viability was maintained, but a significant decrease was observed after exposure to the highest concentration (p < 0.001), associated with cell death by late apoptosis and necrosis. When cell cultures were exposed to AH26®, metabolic activity was highly compromised, resulting in cell death. An imbalance in the production of peroxides and superoxide anion was observed. GuttaFlow® bioseal showed higher biocompatibility than AH26®.

Cytotoxicity of Endodontic Irrigants on Human Periodontal Ligament Cells

Introduction:

Root canal irrigation has an extremely important role in the success of endodontic treatment. During endodontic treatment, the irrigants will be in contact with pulpal and periapical tissues. The purpose of this study was to clarify the potential toxicological implications of NaOCl, EDTA, MTAD, CHX and QMix on periapical and periodontal tissues.

Methods and Materials:

Cytotoxicity of solutions was evaluated on cultured human periodontal ligament (hPDL) that were carefully removed from the middle third of premolar roots. Cytotoxicity of the materials was assessed after 1, 5 and 15 min of exposure using the Mosmann’s Tetrazolium Toxicity (MTT) assay. Optical density of the solution was read at 540-690 nm wavelength. The intensity of color generated correlated with the percentage of viable cells. Data were statistically analyzed using repeated measures ANOVA followed by Bonferroni test.

Results:

The mean percentage of viable cells in all experimental groups was significantly different from sterile saline groups at all time points (P<0.0001). The mean percentage of viable cells significantly decreased over time in MTAD and NaOCl groups. The lowest and highest cytotoxicity belonged to MTAD and EDTA groups, respectively at all the time points (P<0.05).

Conclusion:

MTAD had the lowest cytotoxicity compared to NaOCl, CHX, QMix and EDTA. These impacts have been time dependent. These irrigation fluids may cause unfavorable effects on vital tissues.