Genotoxicity in gingival cells of patients undergoing tooth restoration with two different dental composite materials

Is micronucleus assay a useful marker in gingiva, tongue, and palate for evaluating cytogenetic damage induced by chemical, physical, and biological agents in vivo? A systematic review with meta-analysis

The present systematic review (SR) aims to evaluate manuscripts in order to help further elucidate the following question: is the micronucleus assay (MA) also a useful marker in gingiva, tongue, and palate for evaluating cytogenetic damage in vivo? A search was performed through the electronic databases PubMed/Medline, Scopus, and Web of Science, all studies published up to December 2023. The comparisons were defined as standardized mean difference (SMD), and 95% confidence intervals (CIs) were established. Full manuscripts from 34 studies were carefully selected and reviewed in this setting. Our results demonstrate that the MA may be a useful biomarker of gingival tissue damage in vivo, and this tissue could be a useful alternative to the buccal mucosa. The meta-analysis analyzing the different sites regardless of the deleterious factor studied, the buccal mucosa (SMD = 0.69, 95% CI, - 0.49 to 1.88, p = 0.25) and gingiva (SMD = 0.31, 95% CI, - 0.11 to 0.72, p = 0.15), showed similar results and different outcome for the tongue (SMD = 1.19, 95% CI, 0.47 to 1.91, p = 0.001). In summary, our conclusion suggests that the MA can be a useful marker for detecting DNA damage in gingiva in vivo and that this tissue could be effective site for smearing.

Cytotoxicity effects and differentiation potential of ormocer-based and nanohybrid composite resins on human dental pulp stem cells

OBJECTIVE

to compare conventional nanohybrid (Ceram.x Spectra) and ormocer-based (Admira fusion) dental composite resins effects on human dental pulp stem cells (hDPSCs) in terms of cytotoxicity, self-renewal, migration and osteogenic differentiation.

METHODS

hDPSCs were cultured in presence of different dilutions (undiluted, form 1:2 to 1:100) of CeramX (CX) and Admira fusion (AD) eluates and viability assay in standard or osteogenic conditions were performed. Samples and eluates were prepared according to ISO 10993-12. In addition, apoptosis, self-renewal and migration activity evaluations were carried out. Osteogenic differentiation potential was tested by Alkaline Phosphatase Activity, alizarin red staining and gene expression of specific markers (ALP, RUNX2, OCN, OPN and COL1α1). Statistical analysis was performed by means of a One-way analysis of variance (One-way ANOVA) followed by a Tukey's test for multiple comparison; results were presented as mean ± standard error of mean (SEM).

RESULTS

Admira Fusion demonstrated to be highly biocompatible and showed positive effects on hDPSCs proliferation and differentiation; on the contrary, conventional nanohybrid composite showed to be more cytotoxic and without any notable effect on stem cells differentiation. Moreover, the obtained results were further corroborated by a significant upregulation of osteogenic differentiation markers obtained in presence of ormocer-based composite resin eluate. Specifically, in AD 1:50 group expression levels of ALP, Runx2, Col1α1 were double than control (ALP, p = 0.045; Runx2, p = 0.003; Col1α1, p = 0.001) and CX 1:50 (ALP, p = 0.006; RUNX2, p = 0.029; Col1α1, p = 0.005). Moreover, in the same group, OPN and OCN resulted about 5 times more expressed as compared to control (OPN, p = 0.009; OCN, p = 0.0005) and CX 1:50 (OPN, p = 0.012; OCN, p = 0.0006).

SIGNIFICANCE

The less cytotoxicity obtained by AD than conventional nanohybrid composite may be attributed to a reduced monomers release in the oral environment, supporting the hypothesis of limited adverse effect and enhanced healing potential, mainly when the material is positioned in close contact with pulp tissue.

Cytotoxicity and genotoxicity of various types of endodontic sealers in Chinese hamster ovary (CHO-K1) cells

This study aimed to evaluate the cytotoxicity and genotoxicity of five endodontic sealers (AH Plus, MTA Fillapex, Endoseal MTA, Sealapex, and Zinc oxide eugenol) in Chinese hamster ovary cells. Cytotoxicity was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay to check cell viability at 1, 3, and 7 days. Genotoxicity was assessed by cytokinesis-block micronucleus, single-cell gel electrophoresis, and γH2AX immunofluorescence assays. Cell viability of all endodontic sealers, except Endoseal MTA, on day 1 was less than 100%. Endoseal MTA showed the highest cell viability on day 7. AH Plus and Endoseal MTA showed less DNA damage than other sealers. After complete setting, AH Plus and Endoseal MTA showed low genotoxicity, which could reduce DNA damage in periapical cells, making them suitable as endodontic sealers.

Cytotoxicity and genotoxicity of whitening toothpastes in buccal mucosal cells: a randomized controlled trial

OBJECTIVES

To assess genotoxic and cytotoxic effect of commercially available toothpastes with the different whitening ingredients.

MATERIALS AND METHODS

In vivo assessment of cytotoxicity and genotoxicity of whitening toothpastes with different ingredients using a buccal micronucleus cytome assay (BMCyt assay) comprised 199 participants randomly divided into ten groups based on used whitening or control/conventional toothpaste. The exfoliated buccal mucosal cells were collected, stained, and microscopically evaluated at baseline (T0), 30 days (T1), and 60 days (T2) after the beginning of treatment and 30 days after completing treatment (T3). Statistical evaluation was performed by repeated-measures analysis of variance (two-way ANOVA), Tukey's test, and multiple regression analysis.

RESULTS

The genotoxic parameters showed no biologically significant changes in any of the observed period for the tested toothpastes, while cytotoxic parameters (number of cells with karyorrhexis and condensed chromatin) showed statistically significant difference (P < 0.05) among evaluation periods for the three peroxide-containing toothpastes.

CONCLUSIONS

Peroxide-containing whitening toothpastes exhibit an increase in certain cytotoxic parameters only during the application period, which return to control values after the cessation of application.

CLINICAL SIGNIFICANCE

Whitening toothpastes show no genotoxic effect, while peroxide-containing whitening toothpastes may present significant increase of cytotoxicity (measured by the number of karyorrhexis and condensed chromatin) during the application period. However, these changes observed in clinical conditions cannot be considered significant.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT04460755.

Effect of Rapid Polymerization on Water Sorption and Solubility of Bulk-fill Composites

OBJECTIVES

The aim of the study was to examine the impact of rapid high-intensity polymerization on water sorption and solubility of a new generation of bulk-fill composite materials.

MATERIAL AND METHODS

Five materials were tested: a conventional composite Filtek Z250 (3M, St. Paul, USA) and four bulk-fill composites, Filtek One Bulk Fill (3M), Tetric PowerFill (Ivoclar Vivadent, Schaan, Liechtenstein), Tetric PowerFlow (Ivoclar Vivadent), SDR Plus (Dentsply, Konstanz, Germany). Composite specimens with a 9-mm diameter and a 2-mm height (n = 6) were polymerized with a high-intensity curing unit (Bluephase® PowerCure, Ivoclar Vivadent). The control group was polymerized for a total of 40 s on both sides (1193 mW / cm2) and 3s group for 3 s on one side (3053 mW/cm2). Water sorption and solubility were measured by ISO 4049 method up to 30 days of immersion. The results were statistically analyzed using one-way ANOVA with Tukey post-hoc correction. Different polymerization protocols for the same material were compared by t-test (p <0.05).

RESULTS

The 3s polymerization protocol increased the solubility of all materials. Filtek One Bulk Fill showed the highest water sorption and solubility values, and Tetric PowerFlow proved to be a stable material with low values of tested parameters. During immersion, a saturation of specimens was achieved in low-viscosity bulk-fill composites within two weeks, while in other materials it was not achieved within 30 days, or more, following the immersion.

CONCLUSIONS

Rapid polymerization caused an increase in solubility, which could affect the biocompatibility of the investigated materials not intended for the 3s curing. SDR Plus and Filtek One Bulk Fill should not be polymerized with rapid high-intensity curing due to increased solubility that exceeds ISO 4049:2009 limits.

ASSESSMENT OF CYTOGENETIC DAMAGE TO EXFOLIATED GINGIVAL CELLS IN PATIENTS WITH CHRONIC GENERALIZED PERIODONTITIS

The aim of this cross-sectional study was to investigate the occurrence of chromosomal abnormalities through the frequency of micronuclei and other genomic damage markers in patients with chronic generalized periodontitis and without periodontal disease. Micronucleus assay was performed in exfoliated gingival epithelial cells of 35 patients with generalized chronic periodontitis and 30 control subjects with healthy periodontium. Full mouth clinical examination was performed to define periodontal condition. The mean number of cells with micronuclei observed in chronic periodontitis and control groups was 1.8 (±1.49) and 2.0 (±1.34), respectively. Differences between the groups were not significant (p=0.574). Compared to control subjects, patients with chronic periodontitis showed a significant increase in the number of binucleated cells (p≤0.001) and number of cells with nucleoplasmic bridges (p=0.042). Study results indicated that chronic periodontitis was not associated with higher occurrence of chromosomal damage in gingival cells compared to individuals with healthy periodontium.

In vivo assessment of genotoxicity in buccal cells of children undergoing tooth restoration

OBJECTIVES

Whereas dental materials came in direct or close contact with oral tissue, it is a great concern about the biocompatibility of those materials. This study was performed to evaluate possible DNA damage to buccal cells exposed to dental materials.

METHODS

This prospective, longitudinal clinical study was conducted over a three months period. Class II restorations were placed in 60 young patients with no previous filling using one of three tested dental materials (two glass ionomers; Ketac Molar and Ionofil Molar and one compomer material; Twinky Star). DNA damage was analysed by micronucleus assays, in buccal exfoliated epithelial cells.

RESULTS

In patients treated with Ketac Molar, a significant frequency of micronuclei (p = 0.027) and binucleated cells in samples taken 30 days following restoration (p = 0.029) was confirmed. In patients treated with Twinky Star, a statistically significant increase in the number of binucleated cells in samples taken after 7 and 30 days following restoration (p = 0.001 and p < 0.001, respectively) was observed. In all samples collected 90 days after treatment, there was no statistical difference in the number of any cell changes.

CONCLUSION

In this study long-term biocompatibility of tested materials was confirmed. Glass ionomers and compomers are widely used materials in paediatric dentistry, and this study has proved their safety for usage in children.

In vivo evaluation of fluoride and sodium lauryl sulphate in toothpaste on buccal epithelial cells toxicity

OBJECTIVES

The present study addresses the effect of fluoride and sodium lauryl sulphate content of toothpaste on oral epithelial cells in vivo conditions.

SUBJECTS AND METHOD

Forty volunteers were assigned into two experimental groups, each of them applying the different brand of toothpaste. Every group has been using three different types of toothpaste (non-fluoride and non-SLS, fluoride and non-SLS, and the fluoride and SLS) of the same brand for 6 months, each for 2 months. The buccal epithelial cells were sampled at baseline and 30, 60, 90, 120, 150 and 180 days after the beginning of the research. Effect on DNA damage was analyzed by micronucleus assay Results: After 60 days of use, for both tested kinds of toothpaste with fluoride and without SLS, all studied parameters were not significantly different from the results obtained at the time when the participants used a non-fluoride toothpaste. While, after 60 days of use, for one kind of toothpaste with SLS and fluoride, was observed significantly higher incidence of pyknotic cells (2.20 ± 0.95, 0.00 ± 0.00 vs. 0.05 ± 0.22, respectively; p = .001), cells with karyorrhexis (2.35 ± 1.14, 0.85 ± 0.93 vs. 0.40 ± 0.68, respectively; p = .001), and nuclear buds (1.35 ± 0.68, 0.45 ± 0.51 vs. 0.45 ± 0.60, respectively; p = .001), compared to toothpastes of the same brand with fluoride and without SLS, and without fluoride and without SLS, for the same period.

CONCLUSIONS

Based on the results, can be concluded that there is no fluorine-dependent cytotoxic or genotoxic effect, while SLS dentifrice increases the number of nuclear morphological changes in buccal epithelial cells.

Cytotoxicity and cytokine expression induced by silorane and methacrylate-based composite resins

OBJECTIVE

The aim of this study was to evaluate cytotoxicity and cytokine production induced by light-cured or non-light-cured methacrylate-based and silorane composite resins in RAW 264.7 macrophages.

MATERIAL AND METHODS

Cells were stimulated with the extracts from light-cured or non-light-cured composite resins. After incubation for 24 h, cytotoxicity was assessed with the lactate dehydrogenase (LDH) and methyl thiazolyl tetrazolium (MTT) assays, and total protein was quantified using the Lowry method. TNF-α detection was examined with an enzyme-linked immunosorbent assay (ELISA) conducted with cell supernatants after cell stimulation for 6, 12, and 24 h. Data were analyzed using one-way analysis of variance (ANOVA) and Tukey's post hoc test (α=0.05).

RESULTS

KaloreTM and FiltekTM Silorane were cytotoxic with or without light curing (p<0.05) after 24 h of incubation. KaloreTM stimulated the early production of TNF-α in comparison with control (p<0.05), whereas FiltekTM Silorane did not affect TNF-α levels after 6 and 12 h (p>0.05). However, after 24 h FiltekTM Silorane inhibited the production of TNF-α (p<0.05).

CONCLUSIONS

KaloreTM and FiltekTM Silorane were cytotoxic regardless of light curing. The extract obtained from KaloreTM after 15 days of incubation stimulated the production of TNF-α, unlike that obtained from FiltekTM Silorane.

Evaluation of the genotoxicity and cytotoxicity in the buccal epithelial cells of patients undergoing orthodontic treatment with three light-cured bonding composites by using micronucleus testing

Objective

This study evaluated the cytotoxicity and genotoxicity of fixed orthodontic treatment with three different light-cured orthodontic bonding composites by analyzing micronucleus (MN) formation in the buccal mucosa during a 6-month period.

Methods

Thirty healthy volunteers were selected from consecutive patients referred for orthodontic treatment. Equilibrium 2 brackets and molar tubes (Dentaurum) were bonded with three different light-cured orthodontic bonding composites-Transbond XT (3M Unitek), Kurasper F (Kuraray Europe), or GrenGloo (Ormco Corporation)- to all teeth in both arches. Exfoliated buccal epithelial cells were scraped from the middle part of the inner cheeks with sterile cement spatulas before treatment and at 1, 3, and 6 months after treatment. MNs and nuclear alterations, such as karyorrhexis (KR), karyolysis (KL), and binucleated cells (BNs), were scored under a light microscope. Repeated measure ANOVA was used to calculate statistical differences in degenerative nuclear abnormalities.

Results

MN rates did not significantly differ among different time points within the same cell type (p > 0.05). In contrast, the number of BNs in buccal epithelial cells significantly increased in all composite groups (p < 0.01, Transbond XT; p < 0.001, Kurasper F and GrenGloo). KL frequency significantly increased between the beginning and end of the study in the Kurasfer F (0.80 ± 0.79 to 1.90 ± 1.10; p < 0.05) and GrenGloo (1.30 ± 1.06 to 2.40 ± 1.08; p < 0.05) groups.

Conclusions

After 6 months of fixed orthodontic treatment with different light-cured composites, morphological signs of cytotoxicity were observed but genotoxic effects were absent.