Cytotoxicity of Different Nano Composite Resins on Human Gingival and Periodontal Ligament Fibroblast Cell Lines: An In Vitro Study

Considerations about Cytotoxicity of Resin-Based Composite Dental Materials: A Systematic Review

The dental material industry is rapidly developing resin-based composites (RBCs), which find widespread use in a variety of clinical settings. As such, their biocompatibility has gained increasing interest. This literature review presents a summary of research into the cytotoxicity of methacrylate-based composites published from 2017 to 2023. Subject to analysis were 14 in vitro studies on human and murine cell lines. Cytotoxicity in the included studies was measured via MTT assay, LDH assay, and WST-1 assay. The QUIN Risk of Bias Tool was performed to validate the included studies. Included studies (based entirely on the results of in vitro studies) provide evidence of dose- and time-dependent cytotoxicity of dental resin-based composites. Oxidative stress and the depletion of cellular glutathione (GSH) were suggested as reasons for cytotoxicity. Induction of apoptosis by RBCs was indicated. While composites remain the golden standard of dental restorative materials, their potential cytotoxicity cannot be ignored due to direct long-term exposure. Further in vitro investigations and clinical trials are required to understand the molecular mechanism of cytotoxicity and produce novel materials with improved safety profiles.

A Look Into the Cytotoxicity of Composite Fillings: Friend or Foe?

Dental resin composites are widely used restorative materials in dentistry for the treatment of carious and non-carious lesions as well as pit and fissure sealants, cavity liners, and endodontic sealers. They consist of two parts: an organic resin matrix and an inorganic/organic filler. The organic resin matrix phase is made up of multifunctional monomers and light-sensitive initiators, while the inorganic/organic filler phase is made up of micro/nano-sized fillers that primarily serve as reinforcement. Despite being a very promising dental material, its monomeric component has some drawbacks. It is well known for leaching out during incomplete polymerization, which can result in cytotoxicity. Bis-GMA (bisphenol A-glycidyl methacrylate) is the most cytotoxic of all monomeric components that exhibit synthetic estrogenic effects. The purpose of this article is to assess the cytotoxic effects of dental composite, understand the possible mechanism behind them, and explore ways to screen for and reduce this harmful effect, as well as shed light on its future prospects.

Comparative evaluation of genotoxicity and cytotoxicity of flowable, bulk-fill flowable, and nanohybrid composites in human gingival cells using cytome assay: An in vivo study

Context

Biocompatibility is one of the major prerequisites for safe clinical application of materials. Resin composites release their components into oral environment following restoration which cause adverse reactions.

Aims

To evaluate and compare the genotoxicity and cytotoxicity of flowable, bulk-fill flowable, and nanohybrid composites with glass ionomer cement in human gingival cells using epithelial-based cytome assay.

Methodology

Sixty healthy patients with noncarious cervical lesions were selected and randomly assigned to four groups (n = 15): Group A, glass ionomer cement; Group B, flowable composite; Group C, bulk-fill flowable composite; and Group D, nanohybrid composite. Class V restorations were done in each group with the respective restorative materials. Samples of epithelial cells were collected from gingiva before (control) (T1) and after 10 and 30 days (T2 and T3) postrestoration and examined for the presence of micronuclei and other nuclear anomalies.

Statistical Analysis Used

The results were subjected to statistical analysis using Friedman's test and Kruskal-Wallis test.

Results

The highest level of cytotoxicity was noted at T2 time point with a significant decline at T3 time point. Least cytotoxic damage was exhibited by Group A followed by Group D. Highest cytotoxic effect was shown by Group B followed by Group C. There was no significant level of genotoxicity induced by any of the materials tested at different time points.

Conclusion

There is significant cytotoxicity induced by the tested composite materials which had no long-term effects and no genotoxicity was induced by any of the restorative materials tested.

Cytotoxicity effects of nanohybrid, bulk-fill, and ormocer composites on dental pulp stem cells and human gingival fibroblast cells

Background

Despite significant improvements in the physical and esthetic properties of modern composite resins, there are still concerns about their biocompatibility. The aim of the current study was to evaluate the toxicity of X-tra fil, Grandio, and Admira Fusion composites on dental pulp stem cells (DPSCs) and human gingival fibroblast (HGF) cells.

Materials and Methods

In this in vitro experimental study, 48 composite disks were made using Grandio, Admira Fusion (2 mm high and 4 mm in diameter), and X-tra fil (4 mm high and 4 mm in diameter) composites and cured for 40 s. The composite blocks were then crushed with a sterile mortar and dissolved in phosphate saline buffer solution. Tetrazolium salt (3-(4,5-dimethyl thiazol-2-yl)-2,5 diphenyltetrazolium bromide (MTT_, neutral red (NR) assay, flow cytometry, and quantitative real-time polymerase chain reaction (RT-PCR) tests (n = 5) were used to evaluate the toxicity of the composites on two cell types (HGF, DPSCs). Data were analyzed using one-way ANOVA test followed by Newman-Keuls test. Level of significance was set at P < 0.05.

Results

According to the results of MTT test, only Grandio showed a significant cytotoxicity in DPSCs, but in HGF cells, Grandio and X-tra fil both showed a significant cytotoxicity. In NR test, Grandio and X-tra fil composites showed a significant cytotoxicity on both HGF and DPSC cells. RT-PCR test results on both DPSC and HGF cells indicated that bax gene expression in the Grandio composite was significant. In this test, the nonexpression of the bcl2 gene in DPSCs was significant in Grandio (100 and 200 μg/ml) and in X-tra fil (200 μg/ml). All of the tests performed in this study showed no significant toxicity of Admira fusion.

Conclusion

Admira Fusion is suitable for oral cells in terms of biocompatibility and can be used as a suitable restorative material for deep restorations near the pulp or adjacent to the gums.

Antimicrobial agents in dental restorative materials: a on polymerization, short-term drug release and biological impact

With the aim to design bioactive dental restorative material, the present study investigated the influence of the antimicrobial agents chlorhexidine diacetate (CHX) and octinidine (di)hydrochloride (ODH) when incorporated in two different materials. Selected parameters were polymerization enthalpy, short-term drug release, and the effect on Streptococcus mutans as well as human gingival fibroblasts. Samples were made by mixing a nano-hybrid ormocer (O) and a methacrylate-based nano-hybrid composite (C), each with a mass fraction of 2% CHX or ODH. Release profiles and concentrations of active agents from the resins were assessed, and the cell proliferation of human gingival fibroblasts as well as Streptococcus mutans cultured with the eluates were evaluated. The influence on polymerization was assessed by means of differential scanning calorimetry. Both drugs, especially ODH, showed a decreasing effect on polymerization enthalpies associated with a lowered crosslinking degree. At the same time ODH appeared to be released more persistently than CHX. Moreover, ODH was more efficient with regard to bacteria growth inhibition but also more cytotoxic in terms of reduction of cell viability. ODH is deemed more appropriate for application in a dental resin-based drug delivery system, because of the more persistent drug release than seen for CHX.

Analysis of Cosmetic Effect of Nanocomposite Resin on Anterior Teeth

The problems of anterior teeth include dental plaque, dental caries, and fracture, which are usually treated with common composite resin clinically. Although good repair effect can be achieved, patients are prone to anterior tooth sensitivity after surgery. Therefore, the purpose of this study is to analyze the cosmetic effect of nanocomposite resin on anterior teeth. Up to 176 patients (176 teeth) undergoing anterior dental cosmetic restoration in our hospital were selected and assigned to the LR group (n = 88) and the NR group (n = 88) according to patients' voluntary choice of prosthetic materials. The LR group was cured with light-cured composite resin, while the NR group was cured with nanocomposite resin. By comparing the related indexes of patients in the two groups, it was discovered that in the NR group, the excellent and good rate and patients' evaluation of the repair effect were higher, while the periodontal attachment, gingival index, dental plaque index, VAS score, and the incidence of tooth sensitivity were lower, all P < 0.05. The results indicated that the nanocomposite resin had significant cosmetic effect on anterior teeth and had application value.

Recent update on potential cytotoxicity, biocompatibility and preventive measures of biomaterials used in dentistry

Dental treatment is provided for a wide variety of oral health problems like dental caries, periodontal diseases, periapical infections, replacement of missing teeth and orthodontic problems. Various biomaterials, like composite resins, amalgam, glass ionomer cement, acrylic resins, metal alloys, impression materials, bone grafts, membranes, local anaesthetics, etc., are used for dental applications. The physical and chemical characteristics of these materials influence the outcome of dental treatment. It also impacts on the biological, allergic and toxic potential of biomaterials. With innovations in science and their positive results, there is also a need for awareness about the biological risks of these biomaterials. The aim of dental treatment is to have effective, yet safe, and long-lasting results for the benefit of patients. For this, it is important to have a thorough understanding of biomaterials and their effects on local and systemic health. Materials used in dentistry undergo a series of analyses before their oral applications. To the best of our knowledge, this is the first and original review that discusses the reasons for and studies on the toxicity of commonly used biomaterials for applications in dentistry. It will help clinicians to formulate a methodical approach for the selection of dental biomaterials, thus providing an awareness for forecasting their risk of toxic reactions.

Biological Response Induced in Primary Human Gingival Fibroblasts upon Exposure to Various Types of Injectable Astringent Retraction Agents

Traditional chemo-mechanical retraction/displacement materials can impact the gingival margin tissues. This study was undertaken to analyze biological responses induced in human gingival fibroblasts (HGFs) upon application of injectable astringent-based agents used in the cordless retraction technique. HGFs were exposed to hemostatic agents (five gels, three pastes, and one foam) based on aluminium chloride, aluminium sulphate and ferric sulphate. Changes in cell viability and proliferation were evaluated using an MTT assay and a BrdU assay. The cytoskeleton structure organization (zyxin and F-actin) was visualized by confocal laser scanning microscopy. Oxidative stress was determined using the Griess Reagent System. The RNA expression levels of antioxidant enzymes were quantified by real-time RT-PCR. The statistical significance was evaluated using Student’s t-test and one-way ANOVA with post-hoc Tukey HSD test. The evaluated agents did not downregulate fibroblast viability or proliferation. No significant cytoskeleton reorganization was observed. Only one agent (Expasyl) induced oxidative stress, demonstrated by the increased level of nitrites. Incubation with the studied agents significantly increased the RNA expression of some antioxidant enzymes (SOD1, SOD3, GPX1). However, no significant influence on the expression of SOD2 and HMOX1 was detected. The injectable forms of chemical retraction agents revealed biocompatibility with HGFs, suggesting their potential clinical usefulness in gingival margin retraction.

The effects of low-dose 2-hydroxyethyl methacrylate on apoptosis and survival in human dental pulp cells

BACKGROUND/PURPOSE

2-hydroxyethyl methacrylate (HEMA) is one of the most major components in dentin bonding systems. Uncured HEMA is eluted through the dentin and harmful to pulp cells. The study aimed to investigate the death pattern, morphological change and factors of human dental pulp cells (HDPCs) cultured with low-dose HEMA.

METHODS

HDPCs were cultured with low-dose concentration of HEMA at 0 mM (control), 0.125 mM, 0.25 mM, 1 mM, 2 mM and 4 mM on Day 3 and 5. The cell morphology was observed with F-actin immunocytochemical staining. The flow cytometry was used to analyze the death pattern. NF-κB and Trx-1 were measured using ELISA kits.

RESULTS

The major death pattern was early apoptosis and late apoptosis. The morphological characteristics of apoptosis were observed clearly at 4 mM on Day 3 and Day 5. The phosphorylated NF-κB normalized to total NF-κB protein was significantly higher at 2 mM and 4 mM on Day 5. There was no difference of Trx-1 on Day 3, but significantly higher at 0.25 mM and 1 mM on Day 5. The trend line of phosphorylated NF-κB and Trx-1 showed highly positive correlations with HEMA concentration.

CONCLUSION

The significant cellular morphology characteristics of apoptosis can be observed at higher dose and longer period after exposed to uncured HEMA. The expression of NF-κB was following the ratio of late apoptosis at longer exposure period. Clinically, the remaining dentin thickness should be enough to decrease HEMA concentration and thus to protect pulp cells free from harm.