Pharmacokinetics of ingested fluoride: Lack of effect of chemical compound

Fluoride in drinking water may be present from natural sources or added as sodium fluoride (NaF), sodium silicofluoride (Na2SiF6) or fluorosilicic acid (H2SiF6). Results from an early study with rats suggested that, when ingested as Na2SiF6, the absorption and excretion of fluoride were greater than when ingested as NaF. Objective: The present single-blind, crossover study with 10 adults was done to determine three key pharmacokinetic parameters: the maximum plasma fluoride concentrations (C-max), the elapsed time to reach the maximum concentrations (T-max) and the 6-h areas under the time-plasma concentration curves (AUCs) after ingestion of 500 ml, of water containing 0.67 or 5.45 mg F/L present naturally or added as NaF or H2SiF6. Design: Blood was collected prior to and at nine time points during 6 h after ingestion of the test solutions. Plasma was analysed by electrode after HMDS-facilitated diffusion and the data were analysed for statistically significant differences using repeated measures ANOVA. Results: The C-max, T-max and AUC values after ingestion of the solutions containing natural fluoride, NaF or H2SiF6 did not differ significantly at either dose level. Further, the Tmax values associated with the 0.67 and SAS mg/L solutions did not differ significantly indicating that the absorption, distribution and elimination rates were not affected by the dose size. Conclusions: Considered together with published reports, the present findings support the conclusion that the major features of fluoride metabolism are not affected differently by the chemical compounds commonly used to fluoridate water nor are they affected by whether the fluoride is present naturally or added artificially. (C) 2008 Elsevier Ltd. All rights reserved.

Evaluation of the physical and chemical properties of two commercial and three experimental root-end filling materials

Objective. The aim of this study was to evaluate the pH, calcium release, setting time, and solubility of two commercially available mineral trioxide aggregate (MTA) cements (white MTA Angelus and MTA Bio), and of three experimental cements (light-cured MTA, Portland cement with 20% bismuth oxide and 5% calcium sulfate, and an epoxy resin-based cement). Study design. For evaluation of pH and calcium ion release, polyethylene tubes with 1.0 mm internal diameter and 10.0 mm length were filled with the cements and immediately immersed in flasks containing 10 mL deionized water. After 3, 24, 72, and 168 hours, the tubes were removed and the water from the previous container was measured for its pH and calcium content with a pH meter and an atomic absorption spectrophotometer. For analysis of the setting time, Gilmore needles weighing 100 g and 456.5 g were used, in accordance with the American Society for Testing and Materials specification no. C266-03. Solubility of each cement was also tested. Results. All the cements were alkaline and released calcium ions, with a declining trend over time. After 3 hours, Portland cement + bismuth oxide and MTA Bio had the highest pH and light-cured MTA the lowest. After 1 week, MTA Bio had the highest pH and light-cured MTA and epoxy resin-based cement the lowest. Regarding calcium ion release, after 3 hours, Portland cement + bismuth oxide showed the highest release. After 1 week, MTA Bio had the highest. Epoxy resin-based cement and light-cured MTA had the lowest calcium release in all evaluation periods. Regarding setting times, white MTA Angelus and MTA Bio had the shortest, Portland cement + bismuth oxide had an intermediate setting time, and the epoxy resin-based cement had the longest. The materials that showed the lowest solubility values were the epoxy resin-based cement, Portland cement + bismuth oxide, and light-cured MTA. The highest solubility values were presented in white MTA Angelus and MTA Bio. Conclusions. The white MTA Angelus and MTA Bio had the shortest setting times, higher pH and calcium ion release, and the highest solubility. In contrast, the epoxy resin-based cement and light-cured MTA showed lower values of solubility, pH, and calcium ion release. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2010; 110: 250-256)

Ultrasonic Chemical Vapor Deposition-coated Tip versus High- and Low-speed Carbide Burs for Apicoectomy: Time Required for Resection and Scanning Electron Microscopy Analysis of the Root-end Surfaces

This study compared ultrasonic chemical vapor deposition (CVD)-coated tip (CVDentus #8.1117-1; Clorovale Diamantes Ind. e Com. Ltda Epp, Sao Jose dos Campos, SP, Brazil) versus high-speed (#FG700L) and low-speed (#699) carbide burs for apicoectomy, evaluating the time required for resection and analyzing the root-end surfaces by scanning electron microscopy. Thirty extracted human premolars had the canals instrumented and obturated and were randomly assigned to 3 groups (n = 10), according to the instrument used for root-end resection. The time required for resection of the apical 2 mm of each root was recorded. The resected apical segments were dried, sputter coated with gold, and examined with a scanning electron microscope at X 350 magnification. A four-point (0-3) scoring system was used to evaluate the apical surface smoothness. The results were analyzed statistically by the Kruskal-Wallis test and two-by-two comparisons analyses were performed using the Miller test. The significance level was set at 5%. Root-end resection with the high-speed bur was significantly faster (p < 0.05) compared with the low-speed bur and CVD tip. The carbide burs produced significantly smoother root-end surfaces than the CVD tip (p < 0.05). The low-speed bur produced the smoothest root-end surfaces, whereas the roughest and most irregular root ends (p < 0.05) were obtained with the CVD tip. However, no statistically significant difference (p > 0.05) was found between the high- and low-speed burs regarding the surface roughness of the resected root ends (p > 0.05). In conclusion, under the tested conditions, ultrasonic root-end resection took a longer time and resulted in rougher surfaces compared with the use of carbide burs at both high and low speed. (J Endod 2009;35:265-268)

The mu-way intersection problem for m-cycle systems

An m-cycle system of order upsilon is a partition of the edge-set of a complete graph of order upsilon into m-cycles. The mu -way intersection problem for m-cycle systems involves taking mu systems, based on the same vertex set, and determining the possible number of cycles which can be common to all mu systems. General results for arbitrary m are obtained, and detailed intersection values for (mu, m) = (3, 4), (4, 5),(4, 6), (4, 7), (8, 8), (8, 9). (For the case (mu, m)= (2, m), see Billington (J. Combin. Des. 1 (1993) 435); for the case (Cc,m)=(3,3), see Milici and Quattrochi (Ars Combin. A 24 (1987) 175. (C) 2001 Elsevier Science B.V. All rights reserved.

The metamorphosis of lambda-fold 4-wheel systems into lambda-fold 4-cycle systems

A 4-wheel is a simple graph on 5 vertices with 8 edges, formed by taking a 4-cycle and joining a fifth vertex (the centre of the 4-wheel) to each of the other four vertices. A lambda -fold 4-wheel system of order n is an edge-disjoint decomposition of the complete multigraph lambdaK(n) into 4-wheels. Here, with five isolated possible exceptions when lambda = 2, we give necessary and sufficient conditions for a lambda -fold 4-wheel system of order n to be transformed into a lambda -fold Ccyde system of order n by removing the centre vertex from each 4-wheel, and its four adjacent edges (retaining the 4-cycle wheel rim), and reassembling these edges adjacent to wheel centres into 4-cycles.

On single laws for varieties of quasigroups associated with extended cycle systems

It has been previously shown by Lindner and Rodger that quasigroups associated with 2-perfect extended m-cycle systems can be equationally defined if and only if m is an element of {3, 5, 7}. In this paper we present a single identity for each such m which is equivalent to the identities given for these varieties.

Progressive recovery of osseoperception as a function of the combination of implant-supported prostheses

The extraction of teeth involves the elimination of extremely sensitive periodontal mechanoreceptors, which play an important role in oral sensory perception. Objectives: The aim of this study was to evaluate the recovery of interocclusal sensory perception for micro-thickness in individuals with different types of implant-supported prostheses. Materials and Methods: Wearers of complete dentures (CDs) comprised the negative control group (group A, n=17). The experimental group consisted of wearers of prostheses supported by osseointegrated implants (Group B, n=29), which was subsequently divided into 4 subgroups: B(1) (n=5) - implant supported overdentures (ISO) occluding with CD; B(2) (n=6) - implant-supported fixed prostheses (ISFP) occluding with CD; B3 (n=8) - wearers of maxillary and mandibular ISFP, and B(4) (n=10) - ISFP occluding with natural dentition (ND). Individuals with ND represented the positive control group (Group C, n=24). Aluminum foils measuring 10 mu m, 24 mu m, 30 mu m, 50 mu m, 80 mu m, and 104 mu m thickness were placed within the premolar area, adding up to 120 tests for each individual. Results: The mean tactile thresholds of groups A, B(1), B(2), B(3), B(4), and C were 92 mu m, 27 mu m, 27 mu m, 14 mu m, 10 mu m, and 10 mu m, respectively. [Correction added after publication online 18 April 2008: in the preceding sentence 92 mu m, 27 mu m, 14 mu m, 10 mu m and 10 mu m, was corrected to 92 mu m, 27 mu m, 27 mu m, 14 mu m, 10 mu m and 10 mu m.] The Kruskal-Wallis test revealed significant difference among groups (P < 0.05). The Dunn test revealed that group A was statistically different from groups C, B(3), and B(4), and that B(1) and B(2) were statistically different from group C. Conclusion: Progressive recovery of osseoperception as a function of the combination of implant-supported prostheses could be observed. Moreover, ISO and/or ISFP combinations may similarly maximize the recovery of osseoperception.

Influence of the menstrual cycle on the pressure pain threshold of masticatory muscles in patients with masticatory myofascial pain

Objective. The aim of this study was to investigate the influence of the menstrual cycle and oral contraceptive (OC) intake on the pressure pain threshold (PPT) of masticatory muscles in patients with masticatory myofascial pain (MFP). Study design. The sample was composed of 36 women, divided into 4 groups, according to the presence of MFP and the intake of OC (15 patients had MFP [7 taking OC] and 21 were pain-free controls [8 taking OC]). The algometer-based PPT of masseter and temporalis, and the record of subjective pain by visual analog scale (VAS) were determined during 2 consecutives menstrual cycles at 4 phases (menstrual, follicular, periovulatory, and luteal). A 3-way ANOVA for repeated measurements, Kruskal-Wallis, Friedman, and Dunn tests, with a 5% significant level analyzed the data. Results. PPT was significantly lower in MFP patients when compared with controls throughout the experiment (P < .001). The menstrual phases did not influence PPT (P > .05), while the intake of OC seems to raise PPT levels for the left temporalis (P = .01) and right masseter (P = .04). VAS was, in general, higher at the menstrual phase Conclusions. Different phases of the menstrual cycle have no influence on PPT values, regardless of the presence of a previous condition, as masticatory myofascial pain, while the intake of OC is associated with decreased levels of reported pain.

Effect of repeated cycles of chemical disinfection on the roughness and hardness of hard reline acrylic resins

Objective: The aim of this study was to assess the effect of repeated cycles of five chemical disinfectant solutions on the roughness and hardness of three hard chairside reliners. Methods: A total of 180 circular specimens (30 mm x 6 mm) were fabricated using three hard chairside reliners (Jet; n = 60, Kooliner; n = 60, Tokuyama Rebase II Fast; n = 60), which were immersed in deionised water (control), and five disinfectant solutions (1%, 2%, 5.25% sodium hypochlorite; 2% glutaraldehyde; 4% chlorhexidine gluconate). They were tested for Knoop hardness (KHN) and surface roughness (mu m), before and after 30 simulated disinfecting cycles. Data was analysed by the factorial scheme (6 x 2), two-way analysis of variance (anova), followed by Tukey`s test. Results: For Jet (from 18.74 to 13.86 KHN), Kooliner (from 14.09 to 8.72 KHN), Tokuyama (from 12.57 to 8.28 KHN) a significant decrease in hardness was observed irrespective of the solution used on all materials. For Jet (from 0.09 to 0.11 mu m) there was a statistically significant increase in roughness. Kooliner (from 0.36 to 0.26 mu m) presented a statistically significant decrease in roughness and Tokuyama (from 0.15 to 0.11 mu m) presented no statistically significant difference after 30 days. Conclusions: This study showed that all disinfectant solutions promoted a statistically significant decrease in hardness, whereas with roughness, the materials tested showed a statistically significant increase, except for Tokuyama. Although statistically significant values were registered, these results could not be considered clinically significant.

Cell cycle arrest and apoptosis in TP53 subtypes of bladder carcinoma cell lines treated with cisplatin and gemcitabine

Currently, the combination of cisplatin and gemcitabine is considered a standard chemotherapeutic protocol for bladder cancer. However, the mechanism by which these drugs act on tumor cells is not completely understood. The aim of the present study was to investigate the effects of these two antineoplastic drugs on the apoptotic index and cell cycle kinetics of urinary bladder transitional carcinoma cell lines with wild-type or mutant TP53 (RT4: wild type for TP53; 5637 and T24: mutated TP53). Cytotoxicity, cell survival assays, clonogenic survival assays and flow cytometric analyses for cell cycle kinetics and apoptosis detection were performed with three cell lines treated with different concentrations of cisplatin and gemcitabine. G(1) cell cycle arrest was observed in the three cell lines after treatment with gemcitabine and gemcitabine plus cisplatin. A significant increase in cell death was also detected in all cell lines treated with cisplatin or gemcitabine. Lower survival rates occurred with the combined drug protocol independent of TP53 status. TP53-wild type cells (RT4) were more sensitive to apoptosis than were mutated TP53 cells when treated with cisplatin or gemcitabine. Concurrent treatment with cisplatin and gemcitabine was more effective on transitional carcinoma cell lines than either drug alone; the drug combination led to a decreased cell survival that was independent of TP53 status. Therefore, the synergy between low concentrations of cisplatin and gemcitabine may have clinical relevance, as high concentrations of each individual drug are toxic to whole organisms.

Effect of 980-nanometer diode laser on root canal permeability after dentin treatment with different chemical solutions

This study evaluated the effect of 980-nm diode laser at different parameters on root canal dentin permeability associated with different irrigants. Seventy-five canines were sectioned at 15 mm from the apex, prepared mechanically up to #40 .02 instrument, and irrigated with 2 mL distilled water. Final irrigation (10 mL) was used as follows: (1) distilled water; (2) 1% NaOCl; (3) 17% ethylenediaminetetraacetic acid + a cationic surfactant cetyltrimethylammonium bromide (EDTAC). Laser was applied at 1.5 or 3.0 W as either continuous wave or pulsed wave (100 Hz). The teeth were then processed histochemically, the percentage of copper ion penetration into the dentin of the canal walls was counted, and the data were analyzed statistically with the Tukey-Kramer test (alpha < .01). When laser was associated with water, an increase in permeability was found, whereas permeability decreased when associated with EDTAC. Dentin permeability after laser irradiation was directly dependent on the solution used for final irrigation.

G2 phase cell cycle arrest in human skin following UV irradiation

The contribution of the short wavelength ultraviolet (UV) component of sunlight to the aetiology of skin cancer has been widely acknowledged, although its direct contribution to tumour initiation or progression is still poorly understood. The loss of normal cell cycle controls, particularly checkpoint controls, are a common feature of cancer. UV radiation causes both GI and G2 phase checkpoint arrest in vitro cultured cells. In this study we have investigated the cell cycle responses to suberythemal doses of UV on skin. We have utilized short-term whole organ skin cultures, and multi parameter immunohistochemical and biochemical analysis to demonstrate that basal and suprabasal layer melanocytes and keratinocytes undergo a G2 phase cell cycle arrest for up to 48 h following irradiation. The arrest is associated with increased p16 expression but no apparent p53 involvement. This type of organ culture provides a very useful model system, combining the ease of in vitro manipulation with the ability to perform detailed molecular analysis in a normal tissue environment.