Cytotoxicity of Methacrylate Dental Resins to Human Gingival Fibroblasts

This study aimed to assess the acute and delayed cytotoxicity of three, popular light-cured methacrylate-based restorative resins (MRs): Charisma (C), Estelite (E), and Filtek (F), to human gingival fibroblasts in culture. Cells were grown for up to 24 h with light-cured (or pre-cured) resins. We evaluated resin cytotoxicity, redox imbalance, necrosis/apoptosis, miR-9, and heat shock protein 70 (HSP70). The role of resin-induced oxidative stress (damage) in HSP70-response (repair) was assessed using binary fluorescence labeling. All MRs decreased viable cell numbers and cell proliferation and damaged cell membranes, and their 24 h-delayed toxicity was lower (C), higher (F), or similar (E) to that induced by freshly-cured resins. Cell membrane damage induced by C and E decreased with time, while F produced a linear increase. All resins generated intracellular oxidative stress with the predominant necrotic outcome, and produced heterogeneous responses in miR-9 and HSP70. The double fluorescence (damage/repair) experiments pointed to common features of E and F but not C. In the subset of cells, the binary response induced by E and F was different from C, similar to each other, and positively interrelated. Experimental data show that selective MR cytotoxicity should be taken into account when considering repetitive use or massive reconstruction.

Impact of a toothpaste with microcrystalline hydroxyapatite on the occurrence of early childhood caries: a 1-year randomized clinical trial

The aim of this trial was to determine whether a toothpaste with microcrystalline hydroxyapatite is not inferior to a fluoride toothpaste in prevention of caries in children. This double-blinded randomized control trial compared two toothpastes regarding the occurrence of caries lesions using International Caries Detection and Assessment System (ICDAS) ≥ code 1 on the primary dentition within 336 days. The test group used a fluoride-free hydroxyapatite toothpaste three times daily while control group used a toothpaste with fluoride. 207 children were included in the intention-to-treat analysis; 177 of them finished the study per protocol. An increase in caries ICDAS ≥ code 1 per tooth was observed in 72.7% of the hydroxyapatite-group (n = 88), compared with 74.2% of the fluoride-group (n = 89). The exact one-sided upper 95% confidence limit for the difference in proportion of participants with ICDAS increase ≥ 1 (-1.4%) was 9.8%, which is below the non-inferiority margin of 20% demonstrating non-inferiority of hydroxyapatite compared to the fluoride control toothpaste. This RCT showed for the first time, that in children, the impact of the daily use of a toothpaste with microcrystalline hydroxyapatite on enamel caries progression in the primary dentition is not inferior to a fluoride control toothpaste (Clinical Trials NCT03553966).

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.

Evaluation of cytotoxicity and pH changes generated by various dental pulp capping materials - an in vitro study

INTRODUCTION

Various materials are used in direct dental pulp capping method. Their biocompatibility and alkalizing abilities are of primary importance affecting therapeutic effects. The aim of this study was to evaluate and compare the cytotoxicity of various pulp-capping materials on human gingival fibroblasts and investigate the pH changes induced by these materials.

MATERIAL AND METHODS

Human gingival fibroblasts were cultured with nine direct pulp materials using culture plate inserts. The cytotoxic effects were recorded by using an MTT-based colorimetric assay after 3 and 24 h. In the second part of the experiment, the materials were inserted in dialysis tubes and transferred into plastic vials containing deionized water. The changes of the medium pH were measured after 3 and 24 h.

RESULTS

We showed differences in cell viability of gingival fibroblasts after varied time of exposition for the tested materials. Cell viability after 24 h increased for Dycal, Biopulp, and Calcipro, and decreased for Calcipulpe, Angelus, Angelus White, and ProRoot Regular. Cell viability for ProRoot and Life did not change. Non-setting calcium hydroxide preparations followed by the MTA group and setting calcium hydroxide materials produced the highest pH. All the tested materials significantly increased pH (p < 0.0001) at 24 h.

CONCLUSIONS

Currently used pulp capping materials varied in their cytotoxicity relative to human gingival fibroblasts and their alkalizing capacities. Since most likely pH does not affect the viability of cultured cells, further investigations are required to determine physicochemical properties of these materials and the biological activity of the dental pulp.

Antibacterial activity of two Mineral Trioxide Aggregate materials in vitro evaluation

INTRODUCTION

It has been documented that total removal of carious dentin, assessed according to clinical criteria, does not mean complete eradication of bacteria. For that reason in prevention of caries and pulp inflammations, application of the materials having high antibacterial properties seems to be indispensable.

AIM

Determination of antibacterial activities of two white Mineral Trioxide Aggregate (MTA) preparations against bacteria of the genus Streptococcus.

MATERIAL AND METHODS

Antibacterial activities of the materials were determined by diffusion method on a solid tryptic-soy medium (Tryptic Soy Agar, Oxoid). Wells were prepared on the medium with a puncher of 7 mm diameter and 5 mm depth (four for each material). The bottom was poured with 10 microlitres of liquid TSA for sealing. Bacterial suspension was inoculated with cotton swabs onto the medium surface and then the wells were filled with the materials prepared ex tempore. The plates were left in room temperature for 30 minutes and incubated at 37 degrees C for 24 h. Results were read by measuring the inhibition zones on day 1, 2, 3 and 8 of the culture.

RESULTS

All the study samples demonstrated inhibition of bacteria of the genus Streptococcus. The antibacterial effect of MTA was maintained till the end of the experiment (day 8). ProRoot White showed slightly larger inhibition zone against Streptococcus salivarius and Streptococcus sanguis as compared to MTA white Angelus. The mean inhibition zones against Streptococcus mutans appeared the same for both test materials.

CONCLUSION

The two MTA preparations assessed in the current study show good antibacterial action against the standard strains Streptococcus mutans, Streptococcus sanguis and Streptococcus salivarius.

Evaluation of periodontal status in young patients with insulin-dependent diabetes mellitus (type 1)

PURPOSE

The aim of the study was to value periodontal status in young persons with well-controlled insulin-dependent diabetes mellitus (IDDM).

MATERIAL AND METHODS

We examined 50 young people with IDDM (25 girls and 25 boys) and 50 healthy subjects (25 girls and 25 boys). Mean age of examined persons was about 14 years. We investigated gingival indexes: GI (Gingival Index) and PBI (Papillary Bleeding Index) and periodontal indexes: PI (Periodontal Index) and PDI (Periodontal Disease Index). The results were statistically analysed, and significant differences we observed for p < 0.05.

RESULTS

The mean scores of Gingival Index and Papillary Bleeding Index were lower in healthy subjects but differences were not statistically significant. Only maximum scores of these indexes were significantly higher in diabetics. The mean and maximum values of Periodontal Index were significantly higher in patients with IDDM. We did not notice differences between mean scores of PDI in both examined groups. Analysis of maximum values of Periodontal Disease Index reveals higher level in diabetic girls than in female controls.

CONCLUSIONS

IDDM patients may be at risk of periodontal diseases. Well-controlling insulin-dependent diabetes mellitus may be important for periodontal tissues status and prophylaxis of periodontal diseases.

The effect of glass ionomer cement Fuji IX on the hard tissues of teeth treated by sparing methods (ART and CMCR)

PURPOSE

The aim of the study was to assess the effect of glass ionomer fillings Fuji IX on the mineral content of the hard dental tissues of carious teeth treated by sparing methods.

MATERIAL AND METHODS

The study material consisted of 4 deciduous teeth lost due to physiological resorption. The teeth had glass ionomer fillings Fuji IX inserted after treatment of caries by means of sparing methods (ART and CMCR). Chemical analysis of enamel and dentin was performed by means of energy dispersive spectroscopy (EDS) with X-ray analysis QUEST system at a distance of 20 um (point C) and 120 um (point D), respectively. The content of the following elements was evaluated in weight percent: oxygen (O), fluoride (F), sodium (Na), magnesium (Mg), aluminum (Al), silicon (Si), phosphorus (P), calcium (Ca), strontium (Sr). The Ca/P ratio was calculated. T-student test for pairs, with the level of significance p < 0.05, was used for statistical analysis of the results.

RESULTS

We found significantly higher levels of fluoride, aluminum and silicon and lower concentrations of calcium and phosphorus in the dentine adjacent to the filling (point C). However, no statistically significant differences were observed in the levels of the elements between these two sites of measurement.

CONCLUSIONS

Our results indicate that mineralization of the calcified dentine may involve elements released from glass ionomer cement Fuji IX.

Bacterial composition in the supragingival plaques of children with and without dental caries

PURPOSE

The purpose of the present investigation was to determine if the supragingival bacterial composition plaques in children with caries would differ from those found in caries-free controls.

MATERIAL AND METHODS

Pooled supragingival plaque samples from the smooth surfaces of teeth were collected from 75 children with caries and 131 children without caries. The plaque samples were analysed for bacterial content by cultures on a series of non-selective and selective media for aerobic, microaerophilic and anaerobic bacteria. Additionally, the specimens of dentine carious lesions were examined. The standard culture procedures and identifications of bacteria were used.

RESULTS

Among 131 children without dental caries, 41 (31.3%) were at preschool age with deciduous teeth and 90 (68.7%) at school age with permanent teeth. Dental plaques of caries-free children revealed 452 strains, out of which 326 (72.1%) were from permanent teeth, 126 (27.9%)--from deciduous teeth (p = 0.0001). Among 75 children with dental caries, 61 (81.3%) were at preschool age and 14 (18.7%)--at school age. There were 239 strains isolated from supragingival plaques in children with dental caries, 187 (78.2%) --in preschool children, and 52 (21.8%)--in school children (p < 0.05). From dentine carious lesions in these children, 209 strains were isolated; 164 from preschool children and 45--from school children (p < 0.05). Gram-positive bacteria were isolated more frequently than Gram-negative ones (p = 0.0001) from supragingival plaques both in children with and without dental caries. Streptococcus genus bacteria were isolated more often (p = 0.0002) from the plaques in school children without dental caries. The proportion (%) of aerobic and anaerobic bacteria was comparable (p > 0.05) in dental plaques in children with and without dental caries, except for Veillonella spp., which were isolated more frequently from dental plaques in school children with dental caries (p = 0.01).

CONCLUSIONS

1) Generally, there was no statistically significant difference of bacterial species composition isolated from supragingival plaques in children with deciduous and permanent dental caries and caries-free children. 2) There was no difference between bacterial composition in dentine carious lesions of deciduous teeth and permanent teeth as compared to supragingival plaques in these children (except for Neisseria spp., Peptostreptococcus spp.).

Prevalence rate and antibiotic susceptibility of oral viridans group streptococci (VGS) in healthy children population

PURPOSE

The aim of this study was to evaluated the prevalence rate of oral viridans group streptococci (VGS) and their susceptibilities to some antibiotics in healthy children.

MATERIAL AND METHODS

Samples of pharyngeal swabs and supragingival dental plaques for microbiological studies were collected from 206 healthy children, aged 4-18 years. Additionally, 75 samples of carious lesions from children with dental caries were included. The streptococci were isolated and identified using standard methods and commercial identification kits. For performance of antibacterial susceptibility testing of VGS strains disk diffusion and/or breakpoints procedures were used according to NCCLS standards and criteria. A total of 425 VGS strains were tested against penicillin, ampicillin, erythromycin, clindamycin, tetracycline, doxycycline, ciprofloxacin and vancomycin.

RESULTS

A total of 239 VGS strains belonging to 8 species from pharyngeal swabs of 192 (93.2%) children were isolated. VGS strains from supragingival plaques were isolated in 149 (72.3%) healthy children (p < 0.05), and from carious lesions in 37 (49.3%) children with dental caries. VGS strains of S. mitis species were isolated most frequently from 4-5 year old as compared to 12 and 18 year old children (p < 0.05), while S. vestibularis strains isolated most often in 12 year old ones (p < 0.05). Among 425 VGS strains, high level of penicillin resistance (MIC > or = 2.0 mg/L) was shown in 71 (16.7%) strains, 33 (46.5%) of them belonged to S. mitis species. VGS strains were also resistant to erythromycin (23.5%), clindamycin (23.1%), tetracyclines (T-52%, DOX-16%), gentamycin (25.9%) and ciprofloxacin (55.2%). All VGS strains were vancomycin - susceptible.

CONCLUSIONS

1. In the oral cavities of healthy children, approximately 98% of streptococci belonged to two VGS groups, i.e. mitis and salivarius groups. Streptococci of mutans and anginosus groups were isolated sporadically (2%). 2. We observed difference in susceptibility to penicillin and other antibiotics between the various species of viridans groups streptococci. Mitis group strains (except S. pneumoniae) were more frequently penicillin-resistant (23%) in comparison to salivarius group of VGS strains (9%) (p = 0.0001).