Complement activation as a possible in vitro indication of the inflammatory potential of endodontic materials

Real-time evaluation of the biocompatibility of calcium silicate-based endodontic cements: An in vitro study

INTRODUCTION

An ideal filling material should hermetically seal the communication pathways between the canal system and surrounding tissues. Therefore, during the last few years, the development of obturation materials and techniques to create optimal conditions for the proper healing of apical tissues has been a focus of interest. The effects of calcium silicate-based cements (CSCs) on periodontal ligament cells have been investigated, and promising results have been obtained. To date, there are no reports in the literature that have evaluated the biocompatibility of CSCs using a real-time live cell system. Therefore, this study aimed to evaluate the real-time biocompatibility of CSCs with human periodontal ligament cells (hPDLCs).

METHODOLOGY

hPDLC were cultured with testing media of endodontic cements for 5 days: TotalFill-BC Sealer, BioRoot RCS, Tubli-Seal, AH Plus, MTA ProRoot, Biodentine, and TotalFill-BC RRM Fast Set Putty. Cell proliferation, viability, and morphology were quantified using real-time live cell microscopy with the IncuCyte S3 system. Data were analyzed using the one-way repeated measures (RM) analysis of variance multiple comparison test (p < .05).

RESULTS

Compared to the control group, cell proliferation in the presence of all cements was significantly affected at 24 h (p < .05). ProRoot MTA and Biodentine lead to an increase in cell proliferation; there were no significant differences with the control group at 120 h. In contrast, Tubli-Seal and TotalFill-BC Sealer inhibited cell growth in real-time and significantly increased cell death compared to all groups. hPDLC co-cultured with sealer and repair cements showed a spindle-shaped morphology except with cements Tubli-Seal and TotalFill-BC Sealer where smaller and rounder cells were obtained.

CONCLUSIONS

The biocompatibility of the endodontic repair cements performed better than the sealer cements, highlighting the cell proliferation of the ProRoot MTA and Biodentine in real-time. However, the calcium silicate-based TotalFill-BC Sealer presented a high percentage of cell death throughout the experiment similar to that obtained.

Investigating unset endodontic sealers' eugenol and hydrocortisone roles in modulating the initial steps of inflammation

INTRODUCTION

Endodontic treatment success is achieved not only when the cement provides a hermetic seal but also when the injured periapical tissue is regenerated. However, an exaggerated inflammatory reaction hinders tissue regeneration and it has been shown that dental materials affect the inflammatory response through modulation of cytokine secretion. This work was set to investigate the effects of the presence of hydrocortisone in zinc oxide eugenol sealers (Endomethasone N) on modulating the initial steps of inflammation in vitro.

MATERIAL AND METHODS

Hydrocortisone and eugenol leaching from Endomethasone N and Pulp Canal Sealer (PCS) were quantified by ELISA and spectrofluorometry, respectively. The effects of Endomethasone N and Pulp Canal Sealer were studied on lipopolysaccharides (LPS)-stimulated human periodontal ligament (hPDL) cells. Cytokine (IL-6, TNF-α) secretion from cells was quantified by ELISA. Inflammatory cell (THP-1) adhesion to activated endothelial cells, their migration and activation were studied in vitro.

RESULTS

Endomethasone N decreased secretion of IL-6 and TNF-α from hPDL cells. THP-1 adhesion to activated endothelial cells (HUVECs) and migration significantly decreased with Endomethasone N while no effect was observed with PCS. Activation of THP-1 decreased with both materials' extracts but was significantly lower with Endomethasone N than with PCS.

CONCLUSION

These results performed in vitro show that Endomethasone N anti-inflammatory effects are due to the presence of hydrocortisone.

CLINICAL RELEVANCE

Endomethasone N has potential local anti-inflammatory effects which appear to be due to its hydrocortisone rather than eugenol content. Decreasing the inflammatory response is a pre-requisite to initiate the periapical healing.

Clinical Assessment of Various Obturating Techniques for Primary Teeth: A Comparative Study

INTRODUCTION

Lifelong preservation of tooth in a healthy state is the ultimate goal of dentistry. Premature loss of primary teeth is common due to caries, dental trauma or other causes. As the primary teeth are the best space maintainers, teeth with infected pulps should be retained until exfoliation, whenever possible.

AIM

The purpose of this in vivo study was to evaluate and compare the efficacy of different obturating methods used in primary teeth.

MATERIALS AND METHODS

Forty one patients aged four to nine years with a total of 60 teeth were selected. Out of the 60 teeth, 32 were primary mandibular first molars and 28 were primary mandibular second molars, the sample was randomly divided into three groups. Disposable syringe, lentulo spiral and past inject were used for obturation. Postoperative evaluation was done for; quality of canal obturation, presence of voids using postoperative radiographs following obturation of teeth. The data were analysed to assess the success rate of the three methods used for obturation using Chi-square test.

RESULTS

Among the three groups of the study, past inject exhibited the maximum number of optimally filled canals. Maximum number of underfilled canals was found with lentulospiral, and the maximum number of overfilled canals was seen with disposable syringe. Least number of voids was observed in canals filled with the past inject technique and disposable syringe.

CONCLUSION

The results suggest that the most successful technique for obturation of primary teeth was past inject.

Influence of cyclic heating on physical property and biocompatibility of α- and β-form gutta-percha

BACKGROUND/PURPOSE

Thermoplasticized techniques with high temperature and repetitive heating in root canal filling may cause degeneration of gutta-percha, producing cytotoxic byproducts and interfering sealing quality. This study was conducted to investigate the influence of cyclic heating on the physical property and biocompatibility of α- and β-form gutta-perchas.

METHODS

Both α- and β-form gutta-perchas were submitted to two heating processes: continuous heating and cyclic heating. Continuous heating was carried out by heating the samples up to 300°C and 400°C. The samples were then analyzed by differential scanning calorimetry, differential thermal analysis (DTA), and thermogravimetry. For cyclic heating process, samples were heated from 30°C to 200°C for seven cycles and analyzed with DTA and thermogravimetry. For cell adhesion assay, samples were treated (30°C to 200°C, one and seven cycles), submitted to cell culture and examined by scanning electron microscope.

RESULTS

Differential scanning calorimetry and DTA indicated that α-form gutta-percha presented a major endothermic peak at 50-57°C, while β-form gutta-percha showed two major endothermic peaks at 46-50°C and 60-63°C. Total weight loss of β-form gutta-percha was about 2-fold greater than that of α-form gutta-percha after continuous heating up to 300°C, or cyclic heating for seven times. Scanning electron microscopy showed no obvious difference of cell adhesion on α- and β-form samples, even with seven cyclic heating or one heating cycle. However, the attachment of the cells to the culture plate (the control) is better than to the gutta-percha samples.

CONCLUSION

The increase of heating cycles for α- and β-form gutta-percha exerts no adverse influence on their biocompatibility. Because the physical property of β-form gutta-percha becomes unstable when it is heated at over 300°C or subjected to cyclic heating, β-form gutta-percha may not be recommended for use in thermoplasticized gutta-percha techniques.

Cytotoxicity evaluation of Gutta Flow and Endo Sequence BC sealers

OBJECTIVE

This study evaluated the cytotoxicity of GuttaFlow and EndoSequence BC sealers and compared them with AH Plus and Tubli-Seal sealers.

STUDY DESIGN

Samples (0.5 mg) of freshly mixed or set BC, GuttaFlow, AH Plus, and Tubli-Seal sealers were eluted with 300, 600, and 1,000 μL cell culture medium for 24 and 72 hours. L929 cells were seeded into 96-well plates at 3 × 10(4) cells/well and cultured with 100 μL eluate from each eluate group. Cells cultured only with culture medium served as control. After 24 hours' incubation, the cytotoxicity was evaluated by MTT assay. Cell viability was calculated as the percentage of the control group, and the results were analyzed with a one-way analysis of variance.

RESULTS

For the freshly mixed sealer, cell viability in the AH Plus group was less than in all of the other 3 sealer groups. The Tubli-Seal sealer group had less cell viability than the EndoSequence BC and GuttaFlow sealer groups. For the set sealer, the Tubli-Seal and AH Plus groups had less cell viability than the EndoSequence BC and GuttaFlow sealer groups. There was no cell viability difference between the EndoSequence BC and GuttaFlow sealer groups in the either freshly mixed or set sealer group.

CONCLUSIONS

The GuttaFlow and EndoSequence BC sealers have lower cytotoxicity than the AH Plus and Tubli-Seal sealers.

Laboratory evaluation of the physicochemical properties of a new root canal sealer based on Copaifera multijuga oil-resin

AIM

To compare a new root canal sealer based on Copaifera multijuga oil-resin (Biosealer) using three other established sealers (Sealer 26, Endofill and AH plus) in terms of their physicochemical properties.

METHODOLOGY

The study was carried out according to the requirements of Specification Number 57 of the American Dental Association (ADA) and consisted of the following tests: setting time, flow, film thickness, dimensional stability, radiopacity and solubility/disintegration. Data were analysed statistically using anova and Tukey's test for multiple comparisons. The significance level was set at 5% for all analyses.

RESULTS

Sealer 26 and AH Plus had the longest setting time (P < 0.05). All materials presented flow in with the ADA's guidelines. Regarding film thickness, Sealer 26 did not have a satisfactory performance, as it had a higher mean value than the maximum allowed by the ADA (0.05 mm), being significantly different from the other materials (P < 0.05), which had mean values for film thickness in accordance with the ADA's recommendations. Regarding the solubility and disintegration, only Endofill did not meet the ADA's specifications and presented the worst results of all materials (P < 0.05). Sealer 26 presented the greatest dimensional changes and differed significantly from all other sealers (P < 0.05). Biosealer had the lowest radiopacity values and was significantly different from the other sealers (P < 0.05).

CONCLUSION

The experimental sealer based on Copaifera multijuga oil-resin presented satisfactory results in the physicochemical tests required by the ADA.

In vitro genotoxicity of root canal sealers

AIM

To evaluate the effect of leakage on differences in genotoxicity of root canal sealers ex vivo according to their main components using two different cytogenetic assays.

METHODOLOGY

Six materials of different composition (GuttaFlow, Epiphany, Diaket, IRM, SuperEBA and Hermetic) were tested on human peripheral blood lymphocytes using the comet assay and chromosomal aberration analysis. Prepared materials were eluted in physiological solution for 1 h, 1 day, 5 and 30 days. Thereafter cultures were treated with 8 microg, 4 microg and 2 microg of each sealer. Frequencies of chromatide and chromosome breaks and accentric fragments were determined. Comet assay was used to evaluate primary DNA damage by measuring tail length and tail intensity. Chi-square, Fisher's PLSD (Protected Least Significant Difference) and Kruskall-Wallis non parametric tests were used for statistical analysis.

RESULTS

After 1-h elution only the highest dose of Diaket, Hermetic and SuperEBA significantly (P = 0.035, P = 0.048, P = 0.037 respectively) affected the measured cytogenetic parameters. The migration ability of DNA was more strongly affected than induction of chromosomal aberrations. After elutions longer than 24 h none of the tested sealers exhibited a genotoxic effect.

CONCLUSION

Under the conditions used in the study all sealers had acceptable biocompatibility in terms of genotoxicity.

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.

Labiomandibular paresthesia caused by endodontic treatment: an anatomic and clinical study

Labiomandibular paresthesia after root canal treatment is an accident that is still too frequent despite the development of new endodontic techniques. The aim of this anatomical and clinical study is to advance the understanding of how accidents occur so as to avoid them. This anatomical study made it possible to determine the variability of proximity of the apex of the tooth root to the mandibular bundle, as well as the relationship between the nerve and its satellite artery, and to understand how endodontic filling material spreads into the cancellous bone. The clinical study, which included examination with conventional radiology as well as with imaging techniques, enabled us to identify the exact location of the filling material in relation to the mandibular bundle and to correlate this to the occurrence of clinical symptoms and their diverse manifestations.

A comparative histological evaluation of the biocompatibility of materials used in apical surgery

AIM

To evaluate the biological properties of a variety of materials that could be used in apical surgery.

METHODOLOGY

The intraosseous implant technique recommended by the FDI (1980) and ADA (1982) was used to test the following materials: zinc oxide-eugenol (ZOE), mineral trioxide aggregate (MTA), and Z-100 light-cured composite resin. 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. The connective tissue response alongside the lateral wall outside the cup served as a negative control for the technique. At the end of the observation periods, the animals were killed and the specimens prepared for routine histological examination to evaluate their biocompatibility.

RESULTS

The reaction of the tissue to the materials diminished with time. The ZOE cement was highly toxic during the 4-week experimental period, but this profile changed significantly after 12 weeks, when it showed biocompatible characteristics. MTA and Z-100 showed biocompatibility in this test model at both time periods.

CONCLUSIONS

MTA and Z-100 composite were biocompatible at 4 and 12 weeks in this experimental model.

Biocompatibility of dental materials used in contemporary endodontic therapy: a review. Part 2. Root-canal-filling materials

Root-canal-filling materials are either placed directly onto vital periapical tissues or may leach through dentine. The tissue response to these materials therefore becomes important and may influence the outcome of endodontic treatment. This paper is a review of the biocompatibility of contemporary orthograde and retrograde root-canal-filling materials.

Biocompatibility of root canal filling materials

Results of in vitro and in vivo studies clearly indicate that some endodontic sealers may cause local and systemic adverse effects. Though occasionally contradictory data has been reported from various authors, it may be concluded that zinc-oxide-eugenol sealers possess a marked cytotoxic and tissue-irritating potency. Most Ca(OH)2-based materials, however, were biocompatible. Genotoxic effects have been observed with sealers releasing paraformaldehyde or containing mutagenic substances, such as bisphenol-A-diglycidyl-ether or its derivatives. It cannot be excluded that these materials may pose a systemic risk because formaldehyde is rapidly distributed systemically following its application into the pulp cavity. Furthermore an increasing number of cases with an aspergillosis of the maxillary sinus have been observed which were mainly caused by zinc-releasing endodontic sealers. Overall, it is recommended that for endodontic practice, sealers that have been found to be biocompatible in a "mixed bag" of various in vitro and in vivo tests, be selected. From this point of view, ZnOE-sealers should no longer be used for root canal fillings. This recommendation applies also to sealers containing paraformaldehyde or generating this substance during their setting reaction. More experimental and clinical studies are necessary to elucidate whether new materials, such as mineral trioxide aggregate (MTA) or calcium phosphate cement, will be biocompatible alternatives in the future.

Cytotoxicity of four root canal sealers in permanent 3T3 cells and primary human periodontal ligament fibroblast cultures

OBJECTIVES

The purposes of this study were to determine the cytocompatibility of four endodontic sealers and gutta-percha using various extracts and to compare the cellular injuries resulting from these materials in permanent 3T3 monolayers and primary human periodontal ligament fibroblasts.

STUDY DESIGN

Set specimens from four sealers (AH26, Apexit, Sealapex, N2) as well as gutta-percha were eluted with cell culture medium for 24 hours, 5 days, 5 days, and 24 hours, respectively. Cytotoxic effects due to these extracts were evaluated by determining proliferation of permanent 3T3 cells and primary human periodontal ligament fibroblasts by means of the fluorochrome propidiumiodide.

RESULTS

No statistically significant cellular alterations were induced by gutta-percha and Apexit, whereas various extracts of AH26 and Sealapex caused significant moderate or severe growth inhibition. Severe cellular damage was documented for all extracts of N2, which was statistically significantly different from the other materials in both cell lines (p < 0.05).

CONCLUSIONS

Our results confirm that various root canal sealers constantly segregate substances after being exposed to an aqueous environment for extended periods, possibly causing moderate or severe cytotoxic reactions and possibly contributing to failure.

Cytotoxic effects of gutta-percha solvents

Cytotoxicity of commonly used gutta-percha solvents was evaluated. Gutta-percha dissolved by chloroform, halothane, or turpentine was evaluated with the radiochromium release method using L929 mouse fibroblast cells. All solvents were toxic. Turpentine was most toxic followed by halothane and chloroform, which caused similar levels of cell injury.