[Investigation of the venodilatory effect of vascular endothelial growth factor (VEGF) in rat gingiva]. / A vaszkularis endoteliális növekedési faktor (VEGF) venulákra kifejtett hatásának vizsgálata patkány fogínyben.

VEGF induces proliferation of endothelial cells, stimulates angiogenesis, and increases vascular permeability in many organs. Nevertheless, we have only limited information about its role on gingival hemodynamics, especially in venules. Therefor the aim of this study was to assess the acute circulatory effects of VEGF on rat gingival venules by means of the following protocol. Wister rats (n=63) were devided into five study groups after anesthesia; each animal received 10 microl of experimental solution dripped onto the lower interincisal gingiva. The groups included: 1) saline control (after the experiment, gingiva was excised for VEGF receptor 2 [VEGFR2] immunohistochemistry); 2) VEGF (0.1, 1, 10, or 50 microg/ml); 3) VEGF2 receptor antagonist 5-((7-benzyloxyquinazolin-4-yl)amino)-4-fluoro-2-methyl-phenol-hydrochloride (ZM323881; 20 microg/ml); 4) ZM323881 (20 microg/ml) followed by VEGF application (50 microg/ml after 15 minutes); and 5) VEGF (10 microg/ml), these rats were premedicated with nitric oxide (NO) synthase blocker (NG-nitro-L-arginine-methyl-ester [L-NAME]; 1 mg/ml in drinking water) for 1 week before the experiment. Changes in gingival superficial venule diameter were measured by vital microscopy prior to and 1, 5, 15, 30, and 60 minutes after the administration of the experimental solutions. According to our findings, VEGF dose-dependently increased the venular diameter compared to saline. ZM323881 alone did not cause any alteration. Premedication with ZM323881 or L-NAME decreased the dilatory effects of VEGF. Occassionally moderate VEGFR2 immunohistochemical labeling was observed in the wall components of the venules. Concluding our results we can say, that there is no remarkable VEGF production under physiologic circumstances in rat gingiva, but VEGF is able to increase gingival blood flow through the activation of VEGF2 receptors and consequent NO release.

Venodilatory effect of vascular endothelial growth factor on rat gingiva.

BACKGROUND: Endothelial cell proliferation, angiogenesis, and increased vascular permeability are among the effects of vascular endothelial growth factor (VEGF) in various organs. However, the effects of VEGF on gingival hemodynamics, especially on venules, have not been thoroughly investigated. This study investigated the acute circulatory effects of VEGF on rat gingival venules. METHODS: Fifty-six anesthetized rats were divided into five study groups; each rat received 10 microl of experimental solution dripped onto the lower interincisal gingiva. The groups included: 1) saline control (after the experiment, gingiva was excised for VEGF receptor 2 [VEGFR2] immunohistochemistry); 2) VEGF (0.1, 1, 10, or 50 microg/ml); 3) VEGF2 receptor antagonist 5-((7-benzyloxyquinazolin-4-yl)amino)-4-fluoro-2-methyl-phenol-hydrochloride (ZM323881; 20 microg/ml); 4) ZM323881 (20 microg/ml) followed by VEGF application (50 microg/ml after 15 minutes); and 5) VEGF (10 microg/ml), these rats were premedicated with nitric oxide (NO) synthase blocker (N(G)-nitro-L-arginine-methyl-ester [L-NAME]; 1 mg/ml in drinking water) for 1 week before the experiment. Changes in gingival superficial venule diameter were measured by vital microscopy prior to and 1, 5, 15, 30, and 60 minutes after the administration of the experimental solutions. RESULTS: VEGF dose-dependently increased the venular diameter compared to saline. ZM323881 alone did not cause any alteration. Premedication with ZM323881 or L-NAME decreased the dilatory effects of VEGF. VEGFR2 immunohistochemical labeling was observed in the wall of the venules. CONCLUSIONS: There is no remarkable VEGF production under physiologic circumstances in rat gingiva, but VEGF is able to increase gingival blood flow through the activation of VEGF2 receptors. Furthermore, NO release may contribute to VEGF's vasodilatory effect.

[Comparison of guttapercha points of different brands]. / Különbözô gyártmányú guttaperchacsúcsok összehasonlító vizsgálata.

Many new devices and instruments have been developed in the field of endodontics, however, even today guttapercha is the most commonly used root canal filling material and lateral condensation is still widely the technique of choice. It is crucial that the guttapercha point should not bend away during insertion into the root canal, and that the size of the guttapercha point is in accordance with the size-coding marked on the container. However, there is no data on the difference between the dimensional accuracy and the rigidity of guttapercha points produced by various manufacturers. The aim of the authors' study was to compare guttapercha points of different brands (ANTEOS, DENTSPLY, DIADENT, EXPORDENT, FKG, META, ROEKO, ROSA BECHT, SURE ENDO). The rigidity of guttapercha points (n = 10 in each group) and the dimensional accuracy has been measured (n = 10 in each group) with an instrument developed for this purpose. Statistical analysis has been performed by ANOVA, level of significance was (p < 0.05). In the group FKG significant (p < 0.05) higher forces were necessary to bend guttapercha points. No other significant difference has been shown between the investigated groups (p > 0.05). In the dimensional accuracy there were significant differences (p < 0.05). The least deviation from the assigned dimension has been found in the ROSABECHT group, and the highest in the FKG group. In the dimensional accuracy the least standard error has been found in ROSABECHT group, and the highest in EXPORDENT group. The most extreme deviations have been shown in META and DENTSPLY group. The results of the present study show that guttapercha points frequently deviate from the marked dimension: a guttapercha point from the ISO 25 container may even reach the size of an ISO 30 guttapercha. This has to be taken into account during root canal obturation.

In vitro evaluation of modified surface microhardness measurement, focus variation 3D microscopy and contact stylus profilometry to assess enamel surface loss after erosive-abrasive challenges.

The aim of the study was to compare surface loss values after erosion-abrasion cycles obtained with modified surface microhardness measurement (mSMH), focus variation 3D microscopy (FVM) and contact stylus profilometry (CSP). We cut human molars into buccal and lingual halves, embedded them in resin and ground 200 µm of enamel away. The resulting surfaces were polished. To maintain a reference area, we applied Block-Out resin to partly cover the enamel surface. The samples were incubated in artificial saliva (37°C; 1 h), then rinsed in deionized water (10 s) and dried with oil-free air (5 s). We immersed the specimens individually in 30 mL citric acid (1%, pH 3.6) for 2 min (25°C, 70 rpm dynamic conditions) before brushing them (50 strokes, 200 g) in an automatic brushing machine with toothpaste-slurry. We calculated the surface loss as per mSMH, by re-measuring the length of the same six indentations made before the abrasive challenge. The experiment consisted of five experimental groups that received between 2 and 10 erosion-abrasion cycles. Each group contained 15 specimens and samples in groups 1, 2, 3, 4 and 5 underwent a total of 2, 4, 6, 8 and 10 cycles, respectively. The resin was removed from the reference area in one piece under 10× magnification and the FVM and CSP were performed. Agreement between the methods was calculated with the intraclass correlation coefficient (ICC) and depicted in Bland-Altman plots. All methods presented a linear pattern of surface loss measurements throughout the experiment, leading overall to a strong, statistically significant correlation between the methods (ICC = 0.85; p<0.001). So, despite the different surface loss values, all methods presented consistent results for surface loss measurement.

Expression of Vascular Endothelial Growth Factor Has a Regulatory Role in Gingival Venules in Experimental Diabetes.

BACKGROUND: In the present study, the possible localization and role of vascular endothelial growth factor receptor type 2 (VEGFR2) in the regulation of gingival venules in a rat model of experimental diabetes are examined. METHODS: Six weeks after streptozotocin premedication, Wistar male rats presenting blood sugar levels >20 mmol/L were selected for investigation. The VEGFR2 antagonist ZM323881 [5-((7-benzyloxyquinazolin-4-yl)amino)-4-fluoro-2-methylphenol-hydrochloride] (20 µg/mL) was dripped onto the gingiva between the mandibular incisors. Changes in diameter of the selected gingival venule were measured by vital microscopy combined with digital photography at specified times. Immunohistochemical staining was used to localize VEGFR2. For controls, the same protocol was used on animals with normal blood sugar levels and healthy gingiva. RESULTS: There was a significant difference between the baseline venule diameter of the diabetic and the control groups (47 ± 1 and 28 ± 2 µm, respectively). After 15, 30, and 60 minutes of local application of ZM323881, significant vasoconstriction was observed in the venules of diabetic rats compared with the baseline (81.4% ± 4.6%, 81.8% ± 4.4%, and 80.6% ± 5.1%, respectively). The control group showed no change in the venule diameter. The immunohistochemical analysis showed significantly increased VEGFR2 expression in the mast cells along the venules in the diabetic group, whereas mast cells were rarely found in the control group. CONCLUSIONS: The findings suggest that VEGF expression is increased in gingiva in experimentally induced diabetes. After VEGFR2 activation, the mast cell-derived vasodilatory and inflammatory mediators may contribute markedly to the concomitant changes in the microcirculation.

Effect of dentin powder on the antimicrobial properties of hyperpure chlorine-dioxide and its comparison to conventional endodontic disinfecting agents.

INTRODUCTION: Previously we found that the high purity chlorine-dioxide(ClO2) has a very potent disinfectant efficacy on oral pathogenic microorganisms and as a root canal irrigant it is able to eliminate the experimental Enterococcus faecalis(E. faecalis) infection from the root canal system. This study examines whether the presence of dentin powder influences the antibacterial efficacy of ClO 2. METHODS: In an in vitro dentin powder model the following irrigants were tested against planktonic E. faecalis: 2% chlorhexidine (CHX), 2.5% sodium hypochlorite (NaOCl), 0.12%ClO2 (Solumium) and one local root canal medicament: saturated Ca(OH)2. Survival of bacteria exposed to agents without and with human dentin powder or preincubated with dentin powder was investigated. The effect of the dentin powder on ClO2 concentration was investigated by titrations. RESULTS: Without dentin powder ClO 2 killed all E. faecalis and delivered the best result already after 1 minute; however, after longer contact time with dentin the difference between the disinfectants disappeared. The presence of dentin powder decreased the concentration of ClO 2 and attenuated the antibacterial efficiency of ClO2 and Ca(OH)2, but did not decrease of CHX and NaOCl.Preincubation with dentin powder caused significant loss of antibacterial activity of all investigated agents, ClO2 and Ca(OH)2 having the highest reduction. CONCLUSION: As the presence of dentin powder had a negative effect on the efficacy of disinfectants, the importance of elimination of dentin scrapings and smear layer from the root canal system during endodontic treatments is highly recommended. ClO 2 can be effective for a final rinse.

Comparing the efficacy of hyper-pure chlorine-dioxide with other oral antiseptics on oral pathogen microorganisms and biofilm in vitro.

This study examines the antibacterial properties of sodium hypochlorite (NaOCl), chlorhexidine gluconate (CHX), Listerine®, and high purity chlorine dioxide (Solumium, ClO2) on selected common oral pathogen microorganisms and on dental biofilm in vitro. Antimicrobial activity of oral antiseptics was compared to the gold standard phenol. We investigated Streptococcus mutans, Lactobacillus acidophilus, Enterococcus faecalis, Veillonella alcalescens, Eikenella corrodens, Actinobacillus actinomycetemcomitans and Candida albicans as some important representatives of the oral pathogens. Furthermore, we collected dental plaque from the upper first molars of healthy young students. Massive biofilm was formed in vitro and its reduction was measured after treating it with mouthrinses: CHX, Listerine® or hyper pure ClO2. Their biofilm disrupting effect was measured after dissolving the crystal violet stain from biofilm by photometer. The results have showed that hyper pure ClO2 solution is more effective than other currently used disinfectants in case of aerobic bacteria and Candida yeast. In case of anaerobes its efficiency is similar to CHX solution. The biofilm dissolving effect of hyper pure ClO2 is significantly stronger compared to CHX and Listerine® after 5 min treatment. In conclusion, hyper pure ClO2 has a potent disinfectant efficacy on oral pathogenic microorganisms and a powerful biofilm dissolving effect compared to the current antiseptics, therefore high purity ClO2 may be a new promising preventive and therapeutic adjuvant in home oral care and in dental or oral surgery practice.

Effectiveness of a high purity chlorine dioxide solution in eliminating intracanal Enterococcus faecalis biofilm.

We investigated the effectiveness of chlorine dioxide (ClO2) solution in comparison to sodium hypochlorite (NaOCl) and chlorhexidine gluconate (CHX) in the elimination of intracanal Enterococcus faecalis biofilm. Extracted human teeth were inoculated with E. faecalis. After preparation the canals were irrigated with ClO2, NaOCl, CHX or physiologic saline for control. Two and five days later bacterial samples were collected and streaked onto Columbia agar. CFU/mL were counted. The canal walls were investigated by scanning electron microscopy (SEM). The gas phase was investigated in an upside down Petri dish where E. faecalis was inoculated onto blood agar. The irrigants were placed on absorbent paper into the cover. Bacteria were detectable in the control group, but not in any of the irrigants groups. There was a massive reinfection 2 or 5 days after irrigation in the control group. The lowest reinfection was found after the ClO2 treatment. These findings were confirmed by SEM images. We observed an antibacterial effect of ClO2 and NaOCl gas phases on E. faecalis growth, but not of CHX. ClO2 eliminates intracanal biofilm and keeps canal nearly free from bacteria. We suggest the use of high purity ClO2 as a root canal irrigant in clinical practice.