Curcuma longa L. (turmeric), Rosmarinus officinalis L. (rosemary), and Thymus vulgaris L. (thyme) extracts aid murine macrophages (RAW 264.7) to fight Streptococcus mutans during in vitro infection.

Finding an effective alternative way to aid defense cells to fight Streptococcus mutans was the main goal of this study. The effect of plant extracts from Curcuma longa L. (turmeric), Rosmarinus officinalis L. (rosemary), and Thymus vulgaris L. (thyme) was evaluated on murine macrophages (RAW 264.7) infected by S. mutans. Minimum inhibitory concentration (MIC) of the extracts was determined. Macrophages were infected by S. mutans and treated with each extract. From the supernatants, it was measured nitric oxide (NO) level. Posteriorly, RAW 264.7 were lysed to expose living and phagocytosed bacteria. Cytotoxicity was checked by lysosomal activity analysis, using neutral red assay. Each extract helped RAW 264.7 to eliminate S. mutans during infection, as observed by a significant bacterial reduction. Significant cell viability was also found. Besides, an increased production of NO was verified using R. officinalis L. and T. vulgaris L. extracts. The evaluated extracts demonstrated an effective action to assist RAW 264.7 to fight S. mutans during infection.

Biological Response to Nanosurface Modification on Metallic Biomaterials.

PURPOSE OF REVIEW: New biomaterials for biomedical applications have been developed over the past few years. This work summarizes the current cell lines investigations regarding nanosurface modifications to improve biocompatibility and osseointegration. RECENT FINDINGS: Material surfaces presenting biomimetic morphology that provides nanoscale architectures have been shown to alter cell/biomaterial interactions. Topographical and biofunctional surface modifications present a positive effect between material and host response. Nanoscale surfaces on titanium have the potential to provide a successful interface for implantable biomedical devices. Future studies need to directly evaluate how the titanium nanoscale materials will perform in in vivo experiments. Biocompatibility should be determined to identify titanium nanoscale as an excellent option for implant procedures.

Effects of Brazilian green propolis extract on planktonic cells and biofilms of multidrug-resistant strains of Klebsiella pneumoniae and Pseudomonas aeruginosa.

Propolis could represent an alternative therapeutic agent for targeting multidrug-resistant bacteria due to its antimicrobial potential. The effect of Brazilian green propolis (BGP) aqueous extract (AqExt) was evaluated on eight multidrug-resistant clinical strains of Klebsiella pneumoniae and Pseudomonas aeruginosa, as well as on one reference strain for each bacterial species. The minimum bactericidal concentration (MBC) was determined and optimal concentrations were further evaluated in comparison with 0.12% chlorhexidine. The natural extract was chemically characterized by HPLC-DAD analysis. The MBC values ranged between 3.12 and 27.5 mg ml-1. Analysis of bacterial metabolic activity after treatment for 5 min with BGP-AqExt revealed a strong antimicrobial potential, similar to chlorhexidine. The extract comprised several active compounds including quercetin, gallic acid, caffeic and p-coumaric acid, drupani, galangin, and artepillin C. Altogether, the findings suggest that BGP-AqExt is fast and effective against multidrug-resistant strains of K. pneumoniae and P. aeruginosa in planktonic cultures and biofilms.

Rosmarinus officinalis L. (rosemary) as therapeutic and prophylactic agent.

Rosmarinus officinalis L. (rosemary) is a medicinal plant native to the Mediterranean region and cultivated around the world. Besides the therapeutic purpose, it is commonly used as a condiment and food preservative. R. officinalis L. is constituted by bioactive molecules, the phytocompounds, responsible for implement several pharmacological activities, such as anti-inflammatory, antioxidant, antimicrobial, antiproliferative, antitumor and protective, inhibitory and attenuating activities. Thus, in vivo and in vitro studies were presented in this Review, approaching the therapeutic and prophylactic effects of R. officinalis L. on some physiological disorders caused by biochemical, chemical or biological agents. In this way, methodology, mechanisms, results, and conclusions were described. The main objective of this study was showing that plant products could be equivalent to the available medicines.

Antimicrobial activity of noncytotoxic concentrations of Salvia officinalis extract against bacterial and fungal species from the oral cavity.

The use of medicinal plants can be an alternative method for the control of microorganisms responsible for human infections. This study evaluated the antimicrobial activity of Salvia officinalis Linnaeus (sage) extract on clinical samples isolated from the oral cavity and reference strains of Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus mutans, Candida albicans, Candida tropicalis, and Candida glabrata. In addition, testing assessed the cytotoxic effect of S officinalis on murine macrophages (RAW 264.7). Minimum inhibitory, minimum bactericidal, and minimum fungicidal concentrations of S officinalis extract were determined by broth microdilution method in 60 microbial samples. The cytotoxicity was checked by a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The quantities of the proinflammatory cytokines interleukin 1ß (IL-1ß) and tumor necrosis factor α (TNF-α) produced by RAW 264.7 were analyzed by an enzyme-linked immunosorbent assay. An S officinalis concentration of 50.0 mg/mL was effective against all microorganisms. Regarding cytotoxicity, the groups treated with 50.0-, 25.0-, and 12.5-mg/mL concentrations of S officinalis presented cell viability statistically similar to that of the control group, which was 100% viable. The production of IL-1ß and TNF-α was inhibited at a 50.0-mg/mL concentration of S officinalis. Thus, S officinalis extract presented antimicrobial activity on all isolates of Staphylococcus spp, S mutans, and Candida spp. No cytotoxic effect was observed, as demonstrated by the survival of RAW 264.7 and inhibition of IL-1ß and of TNF-α.

Influence of Chronic Alcohol Use on Osteoblastic Differentiation of Bone Marrow Cells, Bone Properties, and Hepatic and Renal Morphology of Rats.

Chronic alcohol exposure can affect the osteoblastic activity and the proliferation and differentiation of cells due to its toxic effect, which can affect negatively bone repair and bone microarchitecture. The aim of this study was to evaluate the effects of chronic use of 20% alcohol on rats regarding osteoblastic differentiation, extrinsic and intrinsic properties of the tibia, and hepatic and renal morphology. Wistar rats were divided into three groups (n = 9) in accordance with a 24-week diet. After euthanasia, kidneys, liver, and tibias were removed for analysis and femurs mesenchymal cells were collected. The results showed that chronic use of 20% alcohol influenced neither the alkaline phosphatase production nor total protein (p > 0.05) in rats, with similar formation of nodules in all groups (p > 0.05). However, significant changes in the liver and kidneys and adverse effects on the mechanical properties of the tibia were observed. According to the results, it can be concluded that the chronic use of alcohol for 24 weeks had no negative influence on the activity and differentiation of osteoblasts, but the mechanical properties of the tibia were impaired and the organs responsible for metabolism and excretion were also affected due to the consumption of alcohol.

Mouthwashes: an in vitro study of their action on microbial biofilms and cytotoxicity to gingival fibroblasts.

This study evaluated the in vitro antibiofilm effect of 5 different commercial mouthwashes (Cepacol Traditional, Colgate Plax Fresh Mint, Listerine Cool Mint, Oral-B Complete, and Sensodyne) on Candida albicans, Staphylococcus aureus, Enterococcus faecalis, Streptococcus mutans, Escherichia coli, and Pseudomonas aeruginosa. The cytotoxic effect of the mouthwashes on gingival fibroblasts was also analyzed. A colorimetric assay with 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) was used to investigate the viability of biofilms after 48 hours and gingival fibroblasts after 24 hours. The biofilms were exposed to the mouthwashes for 2 different lengths of time: T1, the time recommended by the manufacturer (30 or 60 seconds); and T2, double the recommended time (60 or 120 seconds). All antiseptic mouthwashes caused a significant reduction of biofilm (P < 0.05) as well as a significant reduction of viable gingival fibroblasts (P < 0.05) with both exposure times (T1 and T2). It can be concluded that the commercial mouthwashes demonstrated effective antibiofilm activity; they were more effective on bacteria than on C albicans. A significant cytotoxic effect on gingival fibroblasts was also observed.

Efficacy and safety of blood transfusion in obstetric patients: systematic review of the literature.

OBJECTIVES: To evaluate the efficacy of blood transfusion compared to no intervention in obstetric patients. MATERIAL AND METHODS: A systematic review was performed with Cochrane Database of Clinical Trials, PubMed, EMBASE and LILACS databases searched as of September, 2016. Two authors independently selected relevant clinical trials, assessed their methodological quality and extracted data, using the GRADE approach. RESULTS: Five studies within a total of 6,297 met the inclusion criteria, with women generally aged 20-40 years. Three included studies allocated women to receive blood transfusion or no intervention. Two other studies allocated women with either restricted or full blood supplies. The major issue regarding risk of bias was the extent of concealment of randomization and blinding. There was no statistically significant difference between blood transfusion versus no transfusion or restricted blood supply on mortality (relative risk 0.82 [95% confidential interval 0.32 to 2.09], p = 0.68; two studies; I2 = not applicable). CONCLUSIONS: Very low-quality evidence suggests no significant difference between blood transfusion and no intervention in obstetric patients, underlining the need for more robust clinical trials evaluating this area.

Efficacy of different techniques for removal of calcium hydroxide-chlorhexidine paste from root canals.

The purpose of this study was to evaluate the efficacy of different techniques for removal of combined calcium hydroxide [Ca(OH)2] and chlorhexidine paste from root canals. Fifty single-rooted human teeth were prepared by oscillatory and rotary systems and filled with a paste of Ca(OH)2 and 2% chlorhexidine gel. After incubation for 14 days, the specimens were divided into 5 groups (n = 10), and the medication was removed by 1 of 5 different procedures. In group 1 (control), removal procedures involved a master apical file, foraminal debridement, and 5 mL of saline solution applied with the NaviTip irrigation needle. Group 2 was treated the same as group 1, but in addition 0.5 mL of 17% ethylenediaminetetraacetic acid was used for 3 minutes. In group 3, ultrasonic agitation was performed for 1 minute. Group 4 was treated as group 2, but the NaviTip FX needle was used for irrigation. In group 5, a master apical file, foraminal debridement, and 3-minute application of 5 mL of citric acid were used. After the root-cleaning procedures, the crowns were removed at the cementoenamel junction, and the roots were split longitudinally into halves. The success of intracanal medicament removal was observed under stereoscopic microscope and scanning electron microscope. Remnants of Ca(OH)2 were found in all experimental groups, regardless of the removal technique used. There was no statistically significant difference in cleanliness in the apical third of the root canal among groups 1, 2, and 3. Group 4 showed the best and group 5 the worst results with statistically significant differences. Overall, the NaviTip FX irrigation needle technique was more efficient in removing a Ca(OH)2-chlorhexidine paste from the root canal.

Conventional and whitening toothpastes: cytotoxicity, genotoxicity and effect on the enamel surface.

PURPOSE: To evaluate the cytotoxicity and genotoxicity of whitening and common toothpastes, and the surface roughness of tooth enamel submitted to brushing with both toothpastes. METHODS: Samples of whitening toothpastes [Colgate Whitening (CW) and Oral-B Whitening (OBW)] and regular (non-whitening) toothpastes (Colgate and Oral-B) were extracted in culture medium. Gingival human fibroblasts (FMM-1) were placed in contact with different dilutions of culture media that had been previously exposed to such materials, and the cytotoxicity was evaluated using the MTT assay. The genotoxicity was assessed by the micronucleus formation assay in Chinese hamster fibroblasts (V79). The cell survival rate and micronuclei number were assessed before and after exposure to the toothpaste extracts. For the surface roughness evaluation, 20 bovine tooth specimens, divided into four groups according to toothpastes, were submitted to 10,000 brushing cycles. The results were analyzed using the Mann-Whitney U and two-way ANOVA tests (P < 0.05). RESULTS: MTT assay showed that Colgate was significantly less cytotoxic than CW, Oral-B and OBW at all dilutions (P < 0.01). CW was the most cytotoxic toothpaste (P < 0.01). The whitening toothpastes showed the highest numbers of micronuclei compared to the untreated control (UC) (P < 0.01). Colgate and Oral-B toothpastes were not genotoxic compared to UC (P = 0.326). The OBW toothpaste was statistically significantly abrasive to the enamel surface (P < 0.01). The whitening toothpastes and Oral-B were cytotoxic to the cells. The whitening toothpastes were more genotoxic to cells in vitro than the common toothpastes, and genotoxicity was more pronounced in the OBW toothpaste.

Impact of Silicon Carbide Coating and Nanotube Diameter on the Antibacterial Properties of Nanostructured Titanium Surfaces.

This study aimed to comprehensively assess the influence of the nanotube diameter and the presence of a silicon carbide (SiC) coating on microbial proliferation on nanostructured titanium surfaces. An experiment used 72 anodized titanium sheets with varying nanotube diameters of 50 and 100 nm. These sheets were divided into four groups: non-coated 50 nm titanium nanotubes, SiC-coated 50 nm titanium nanotubes, non-coated 100 nm titanium nanotubes, and SiC-coated 100 nm titanium nanotubes, totaling 36 samples per group. P. gingivalis and T. denticola reference strains were used to evaluate microbial proliferation. Samples were assessed over 3 and 7 days using fluorescence microscopy with a live/dead viability kit and scanning electron microscopy (SEM). At the 3-day time point, fluorescence and SEM images revealed a lower density of microorganisms in the 50 nm samples than in the 100 nm samples. However, there was a consistently low density of T. denticola across all the groups. Fluorescence images indicated that most bacteria were viable at this time. By the 7th day, there was a decrease in the microorganism density, except for T. denticola in the non-coated samples. Additionally, more dead bacteria were detected at this later time point. These findings suggest that the titanium nanotube diameter and the presence of the SiC coating influenced bacterial proliferation. The results hinted at a potential antibacterial effect on the 50 nm diameter and the coated surfaces. These insights contribute valuable knowledge to dental implantology, paving the way for developing innovative strategies to enhance the antimicrobial properties of dental implant materials and mitigate peri-implant infections.

Cytotoxicity of Brazilian plant extracts against oral microorganisms of interest to dentistry.

BACKGROUND: With the emergence of strains resistant to conventional antibiotics, it is important to carry studies using alternative methods to control these microorganisms causing important infections, such as the use of products of plant origin that has demonstrated effective antimicrobial activity besides biocompatibility. Therefore, this study aimed to evaluate the antimicrobial activity of plant extracts of Equisetum arvense L., Glycyrrhiza glabra L., Punica granatum L. and Stryphnodendron barbatimam Mart. against Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus mutans, Candida albicans, Candida tropicalis, and Candida glabrata, and to analyze the cytotoxicity of these extracts in cultured murine macrophages (RAW 264.7). METHODS: Antimicrobial activity of plant extracts was evaluated by microdilution method based on Clinical and Laboratory Standards Institute (CLSI), M7-A6 and M27-A2 standards. The cytotoxicity of concentrations that eliminated the microorganisms was evaluated by MTT colorimetric method and by quantification of proinflammatory cytokines (IL-1ß and TNF-α) using ELISA. RESULTS: In determining the minimum microbicidal concentration, E. arvense L., P. granatum L., and S. barbatimam Mart. extracts at a concentration of 50 mg/mL and G. glabra L. extract at a concentration of 100 mg/mL, were effective against all microorganisms tested. Regarding cell viability, values were 48% for E. arvense L., 76% for P. granatum L, 86% for S. barbatimam Mart. and 79% for G. glabra L. at the same concentrations. About cytokine production after stimulation with the most effective concentrations of the extracts, there was a significant increase of IL-1ß in macrophage cultures treated with S. barbatimam Mart. (3.98 pg/mL) and P. granatum L. (7.72 pg/mL) compared to control (2.20 pg/mL) and a significant decrease of TNF-α was observed in cultures treated with G. glabra L. (4.92 pg/mL), S. barbatimam Mart. (0.85 pg/mL), E. arvense L. (0.83 pg/mL), and P. granatum L. (0.00 pg/mL) when compared to control (41.96 pg/mL). CONCLUSIONS: All plant extracts were effective against the microorganisms tested. The G. glabra L. extract exhibited least cytotoxicity and the E. arvense L. extract was the most cytotoxic.

Enhancing the Hydrophobicity and Antibacterial Properties of SiCN-Coated Surfaces with Quaternization to Address Peri-Implantitis.

Peri-implantitis is a major cause of dental implant failure. This disease is an inflammation of the tissues surrounding the implant, and, while the cause is multi-factorial, bacteria is the main culprit in initiating an inflammatory reaction. Dental implants with silicon carbonitride (SiCN) coatings have several potential advantages over traditional titanium implants, but their antibacterial efficiency has not yet been evaluated. The purpose of this study was to determine the anti-bacterial potential of SiCN by modifying the surface of SiCN-coated implants to have a positive charge on the nitrogen atoms through the quaternization of the surface atoms. The changes in surface chemistry were confirmed using contact angle measurement and XPS analysis. The modified SiCN surfaces were inoculated with Streptococcus mutans (S. mutans) and compared with a silicon control. The cultured bacterial colonies for the experimental group were 80% less than the control silicon surface. Fluorescent microscopy with live bacteria staining demonstrated significantly reduced bacterial coverage after 3 and 7 days of incubation. Scanning electron microscopy (SEM) was used to visualize the coated surfaces after bacterial inoculation, and the mechanism for the antibacterial properties of the quaternized SiCN was confirmed by observing ruptured bacteria membrane along the surface.

Bactericidal effects of two parameters of Er:YAG laser intracanal irradiation: ex-vivo study.

The success of endodontic treatment depends on the complete elimination of microorganisms from the root canal system, thus the search for new procedures to eliminate them is justified. The aim of this study was to assess bacterial reduction after intracanal irradiation with the Er:YAG laser. The canals of 70 extracted human maxillary canines were prepared up to file #40 using 1% NaOCl, irrigated with 17% EDTA, and then washed with physiological solution activated by ultrasound. The roots were sterilized by autoclaving, inoculated with 10 µl of a suspension containing 1.5 × 10(8) CFU/ml of Enterococcus faecalis ATCC 29212 and incubated at 37°C for 72 h. The canals were irradiated with the Er:YAG laser using two energy settings: 60 mJ and 15 Hz, and 100 mJ and 10 Hz. The remaining bacteria were counted immediately and 48 h after laser irradiation. The results showed a high bacterial reduction at both time points. With 60 mJ and 15 Hz there was an immediate reduction of 99.73% and the reduction was 77.02% after 48 h, and with 100 mJ and 10 Hz there was an immediate reduction of 99.95% and the reduction was 84.52% after 48 h. Although the best results were observed with 100 mJ of energy, the difference between the two settings was not statistically significant. The count performed 48 h after irradiation showed that E. faecalis were able to survive, and can grow even from small numbers.

Effect of Silicon Carbide Coating on Osteoblast Mineralization of Anodized Titanium Surfaces.

The objective of this study was to evaluate the influence of the titanium nanotube diameter and the effect of silicon carbide (SiC) coating on the proliferation and mineralization of pre-osteoblasts on titanium nanostructured surfaces. Anodized titanium sheets with nanotube diameters of 50 and 100 nm were used. The following four groups were tested in the study: (1) non-coated 50 nm nanotubes; (2) SiC-coated 50 nm titanium nanotubes; (3) non-coated 100 nm nanotubes and (4) SiC-coated 100 nm nanotubes. The biocompatibility and cytotoxicity of pre-osteoblasts were evaluated using a CellTiter-BlueCell Viability assay after 1, 2, and 3 days. After 3 days, cells attached to the surface were observed by SEM. Pre-osteoblast mineralization was determined using Alizarin-Red staining solution after 21 days of cultivation. Data were analyzed by a Kruskal−Wallis test at a p-value of 0.05. The results evidenced biocompatibility and non-cytotoxicity of both 50 and 100 nm diameter coated and non-coated surfaces after 1, 2 and 3 days. The statistical analysis indicates a statistically significant higher cell growth at 3 days (p < 0.05). SEM images after 3 days demonstrated flattened-shaped cells without any noticeable difference in the phenotypes between different diameters or surface treatments. After 21 days of induced osteogenic differentiation, the statistical analysis indicates significantly higher osteoblast calcification on coated groups of both diameters when compared with non-coated groups (p < 0.05). Based on these results, we can conclude that the titanium nanotube diameter did not play any role on cell viability or mineralization of pre-osteoblasts on SiC-coated or non-coated titanium nanotube sheets. The SiC coating demonstrated biocompatibility and non-cytotoxicity and contributed to an increase in osteoblast mineralization on titanium nanostructured surfaces when compared to non-coated groups.

Toxicity and effect of whitening toothpastes on enamel surface.

This in vitro study evaluated the biocompatibility and abrasivity of whitening and conventional toothpastes. Samples of conventional (non-whitening) - Edel White Infant (EWI) - and whitening toothpastes - Edel White Whitening (EWW), Edel White CAREFORTE (EWC), Colgate Total 12 Ò Professional (C), and Oral-B Whitening (OB) - were dissolved in culture medium (0.2 g sample weight per mL). Human gingival fibroblasts (hGF) were placed in contact with different dilutions of culture media that had been previously exposed to these toothpastes. Cytotoxicity was then assessed using the methyl tetrazolium test (MTT) and the cell survival rate was determined. Genotoxicity was assessed by the micronucleus test (MNT) and the number of micronuclei was determined before and after exposure to the toothpaste solutions. The enamel surface roughness was evaluated in specimens of bovine teeth (n = 10 per group) before and after 10,000 brushing cycles, using the investigated toothpastes. The results were statistically analyzed using the Mann-Whitney U test and two-way ANOVA (p < 0.05). According to the MTT assay, EWW and OB presented significant cytotoxicity (p < 0.01), but no genotoxic (MNT) effects (p > 0.05). C toothpaste was statistically significantly abrasive to the enamel surface (p < 0.01). The findings of this study may be helpful for individualized selection of commercial toothpastes, as some whitening toothpastes present significant cytotoxicity and conventional toothpaste cause significant surface changes.

Nanostructured Surfaces to Promote Osteoblast Proliferation and Minimize Bacterial Adhesion on Titanium.

The objective of this study was to investigate the potential of titanium nanotubes to promote the proliferation of human osteoblasts and to reduce monomicrobial biofilm adhesion. A secondary objective was to determine the effect of silicon carbide (SiC) on these nanostructured surfaces. Anodized titanium sheets with 100-150 nm nanotubes were either coated or not coated with SiC. After 24 h of osteoblast cultivation on the samples, cells were observed on all titanium sheets by SEM. In addition, the cytotoxicity was evaluated by CellTiter-BlueCell assay after 1, 3, and 7 days. The samples were also cultivated in culture medium with microorganisms incubated anaerobically with respective predominant periodontal bacteria viz. Porphyromonas gingivalis, Treponema denticola, and Tannerella forsythia as monoinfection at 37 °C for 30 days. The biofilm adhesion and coverage were evaluated through surface observation using Scanning Electron Microscopy (SEM). The results demonstrate that Ti nanostructured surfaces induced more cell proliferation after seven days. All groups presented no cytotoxic effects on human osteoblasts. In addition, SEM images illustrate that Ti nanostructured surfaces exhibited lower biofilm coverage compared to the reference samples. These results indicate that Ti nanotubes promoted osteoblasts proliferation and induced cell proliferation on the surface, compared with the controls. Ti nanotubes also reduced biofilm adhesion on titanium implant surfaces.

Novel Coatings to Minimize Corrosion of Titanium in Oral Biofilm.

The aim of this work is to investigate the effects produced by polymicrobial biofilm (Porphyromonas gingivalis, Streptococcus mutans, Streptococcus sanguinis, and Streptococcus salivarius) on the corrosion behavior of titanium dental implants. Pure titanium disks were polished and coated with titanium nitride (TiN) and silicon carbide (SiC) along with their quarternized versions. Next, the disks were cultivated in culture medium (BHI) with P. gingivalis, S. mutans, S. sanguinis, and S. salivarius and incubated anaerobically at 37 °C for 30 days. Titanium corrosion was evaluated through surface observation using Scanning Electron Microscope (SEM) and Atomic Force Microscopy (AFM). Furthermore, the Ti release in the medium was evaluated by Inductively Coupled Plasma Mass Spectrometry (ICP-MS). SEM images showed that coated Ti disks exhibited lower corrosion compared to non-coated disks, except for the quartenized TiN. This was confirmed by AFM, where the roughness was higher in non-coated Ti disks. ICP showed that Ti levels were low in all coating disks. These results indicate that these SiC and TiN-based coatings could be a useful tool to reduce surface corrosion on titanium implant surfaces.

Peroxide penetration from the pulp chamber to the external root surface after internal bleaching.

PURPOSE: To quantify the amount of peroxide penetration from the pulp chamber to the external surface of teeth during the walking bleaching technique. METHODS: Seventy-two bovine lateral incisors were randomly divided over five experimental groups and one control (n = 12 per group): (1) 35% hydrogen peroxide (HP); (2) 35% carbamide peroxide (CP); (3) sodium perborate (SP); (4) (HP+SP); (5) (CP+SP) and (6) Control (CG), deionized water. All groups were treated according to the walking bleach technique. After 7 days at 37 degrees C in an acetate buffer solution, 100 microl violet leukocrystal coloring and 50 microl peroxidase was added, producing a blue stain that could be measured in a spectrophotometer and then converted into peroxide microg/ml. RESULTS: G5 exhibited the greatest penetration, while G2 and G3 produced the lowest values. All bleaching agents penetrated from the pulp chamber to the external root surface. There was a direct correlation between the presence of oxidative agents and penetration potential. Sodium perborate in distilled water was less oxidative and appeared to be the least aggressive bleaching agent.

Comparison between conventional and chemomechanical approaches for the removal of carious dentin: an in vitro study.

The present study aimed to evaluate the efficiency, effectiveness, and biocompatibility of two agents used for the chemomechanical removal of carious dentin. Sixty extracted carious human teeth were treated with a conventional bur (CBG) or chemomechanical agents - Papacarie Duo (PG) and Brix 3000 (BG). Treatment efficiency and effectiveness were assessed by the working time for carious dentin removal and Knoop microhardness values, respectively. Human pulp fibroblasts (FP6) were used to evaluate cytotoxicity by incorporating MTT dye, and genotoxicity was evaluated with the micronuclei test. The carious tissue was removed in a shorter time with CBG (median = 54.0 seconds) than the time required for chemomechanical agents (p = 0.0001). However, the time was shorter for Brix 3000 (BG) than that for Papacarie Duo (PG), showing mean values of 85.0 and 110.5 seconds, respectively. Regarding microhardness testing, all approaches tested were effective (p < 0.05). The final mean microhardness values were 48.54 ± 16.31 KHN, 43.23 ± 13.26 KHN, and 47.63 ± 22.40 KHN for PG, BG, and CBG, respectively. PG decreased cell viability compared to that of BG, but it presented no genotoxicity. Brix 3000 may be a good option for chemomechanical dentin caries removal due to its reduced removal time and lower cytotoxicity compared to the other treatment options.