Glass transition temperature of hard chairside reline materials after post-polymerisation treatments

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effectiveness of Screw Surface Coating on the Stability of Zirconia Abutments After Cyclic Loading

Purpose: Different surface treatments have been developed in attempts to prevent the loosening of abutment screws. The aim of the current study was to compare the effectiveness of titanium alloy screws with tungsten-doped diamond-like carbon (W-DLC) coating and uncoated screws in providing stability to zirconia (ZrO2) ceramic abutments after cyclic loading. Materials and Methods: Twenty prefabricated ZrO2 ceramic abutments on their respective external-hex implants were divided into two groups of equal size according to the type of screw used: uncoated titanium alloy screw (Ti) or titanium alloy screw with W-DLC coating (W-DLC/Ti). The removal torque value (preload) of the abutment screw was measured before and after loading. Cyclic loading between 11 and 211 N was applied at an angle of 30 degrees to the long axis of the implants at a frequency of 15 Hz. A target of 0.5 x 10(6) cycles was defined. Group means were calculated and compared using analysis of variance and the F test (alpha=.05). Results: Before cyclic loading, the preload for Ti screws was significantly higher than that for W-DLC/Ti screws (P=.021). After cyclic loading, there was no significant difference between them (P=.499). Conclusions: Under the studied conditions, it can be concluded that, after cyclic loading, both abutment screws presented a significant reduction in the mean retained preload and similar effectiveness in maintaining preload. INT J ORAL MAXILLOFAC IMPLANTS 2012;27:1061-1067

Cytotoxicity of denture base and hard chairside reline materials: a systematic review

Statement of problem. Adverse reactions to the materials used for the fabrication and reline of removable denture bases have been observed.Purpose. The purpose of this study was to systematically review the published literature on the cytotoxicity of denture base and hard reline materials.Material and methods. MEDLINE via PubMed, Google Scholar, and Scopus databases for the period January 1979 to December 2009 were searched with the following key words: (biocompatibility OR cytotoxic* OR allergy OR burning mouth OR cell culture techniques) and (acrylic resins OR denture OR monomer OR relin* OR denture liners). The inclusion criteria included in vitro studies using either animal or human cells, in which the cytotoxicity of the denture base and hard chairside reline resins was tested. Studies of resilient lining materials and those that evaluated other parameters such as genotoxicity and mutagenicity were excluded. Articles published in the English language and in peer-reviewed journals focusing on the cytotoxicity of these materials were reviewed.Results. A total of 1443 articles were identified through the search. From these, 20 studies were judged to meet the selection criteria and were included in the review. In the majority of the studies, continuous cell lines were exposed to eluates of specimens made from the materials, and mitochondrial activity was used to estimate cell viability. The tested acrylic resins were grouped according to 5 major categories: (1) heat-polymerized; (2) microwave-polymerized; (3) autopolymerizing; (4) light-polymerized; and (5) hard chairside reliners.Conclusions. This review provided some evidence that the heat-polymerized resins showed lower cytotoxic effects than autopolymerizing denture base acrylic resins and light or dual polymerized reline resins. However, because of the large number of variables in the reviewed literature, a definitive conclusion could not be drawn. (J Prosthet Dent 2012;107:114-127)

Cytotoxicity of monomers, plasticizer and degradation by-products released from dental hard chairside reline resins

Objectives. The aim of this study was to evaluate the cytotoxic effect of the monomers isobutyl methacrylate (IBMA) and 1,6-hexanediol dimethacrylate (1,6-HDMA), the plasticizer di-n-butyl phthalate (DBP), and the degradation by-products methacrylic acid (MA) and benzoic acid (BA) on L929 cells. Based on previous investigations on the release of these compounds from hard chairside reline resins, a range of concentrations (mu mol/L) were selected for the cytotoxicity tests (IBMA, 5.491406.57; 1,6-HDMA, 1.2239.32; DBP, 1.12143.8; MA, 9.07581; BA, 3.19409).Methods. Cytotoxic effects were assessed using MTT and 3H-thymidine assays after the cells had been exposed to the test compounds at the given concentrations for 24h. Cytotoxicity was rated based on cell viability relative to controls (cells exposed to medium without test substances).Results. DNA synthesis activity was inhibited by all compounds. Mitochondrial dehydrogenase activity decreased in cells treated with monomers, plasticizer and MA by-product, whereas no cytotoxic effect was observed on contact with BA at the majority of concentrations tested. The ranges of suppression for 3H-thymidine assay were: IBMA, 2595%; 1,6-HDMA, 9598%; DBP, 4098%; MA, 9799%; BA, 5471%. For MTT assay, the ranges of suppression were: IBMA, 096%; 1,6-HDMA, 2689%; DBP, 1780%; MA, 5266%; BA, 027%. The 3H-thymidine assay was more sensitive than the MTT assay.Significance. This study evaluated the cytotoxicity of a wide range of concentrations of monomers (IBMA and 1,6-HDMA), plasticizer (DBP) and degradation by-products (MA and BA), including those expected to be released from hard chairside reline resins. The differences observed in the cytotoxicity of these compounds, along with other properties, may assist the dental practitioners in the selection of reline materials with improved service life performance and low risk of adverse reactions in patients who wear relined dentures.

Exothermic Behavior, Degree of Conversion, and Viscoelastic Properties of Experimental and Commercially Available Hard Chairside Reline Resins

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Leachability of degradation products from hard chairside reline resins in artificial saliva: effect of water-bath post-polymerization treatment

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

IMPROVEMENT TO THE MARGINAL COPING FIT of COMMERCIALLY PURE TITANIUM CAST IN PHOSPHATE-BONDED INVESTMENT BY USING A SIMPLE PATTERN COATING TECHNIQUE

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effect of water-bath post-polymerization on the mechanical properties, degree of conversion, and leaching of residual compounds of hard chairside reline resins

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Biological Response to Wollastonite Doped alpha-Tricalcium Phosphate Implants in Hard and Soft Tissues in Rats

The biological response following subcutaneous and bone implantation of beta-wollastonite(beta-W)-doped alpha-tricalcium phosphate bioceramics in rats was evaluated. Tested materials were: tricalciurn phosphate (TCP), consisting of a mixture of alpha- and beta-polymorphs; TCP doped with 5 wt. % of beta-W (TCP5W), composed of alpha-TCP as only crystalline phase; and TCP doped with 15 wt. % of beta-W (TCP15), containing crystalline alpha-TCP and beta-W. Cylinders of 2x1 mm were implanted in tibiae and backs of adult male Rattus norvegicus, Holtzman rats. After 7, 30 and 120 days, animals were sacrificed and the tissue blocks containing the implants were excised, fixed and processed for histological examination. TCP, TCP5W and TCP15W implants were biocompatible but neither bioactive nor biodegradable in rat subcutaneous tissue. They were not osteoinductive in connective tissue either. However, in rat bone tissue beta-W-doped alpha-TCP implants (TCP5W and TCP15W) were bioactive, biodegradable and osteoconductive. The rates of biodegradation and new bone formation observed for TCP5W and TCP15W implants in rat bone tissue were greater than for non-doped TCP.

Morphological changes on the hard palatine mucosa of rats (Rattus norvegicus albinus) after chronic alcohol consumption

In order to examine the effects of alcohol on the hard palatine mucosa of rats, sixty adult female rats (Rattus norvegicus albinus) were divided into two experimental groups. The control group received solid diet (Purina rat chow) and tap water ad libitum. The alcoholic group received the same solid diet and was allowed to drink only sugar cane brandy dissolved in 30% Gay Lussac (v/v). At the end of periods of 90, 180 and 270 days of treatment, the animals at estro were sacrificed and the hard palatine mucosa were prepared for TEM and SEM methods. The basal cells of the alcoholic groups (90, 180 and 270 days of treatment) demonstrated some alterations: the intercellular spaces between these cells were higher, presented cytoplasmatic lipid droplets and autolysis. Also, the connective tissue showed intense lipid droplets accumulation in the alcoholic groups. These modifications suggested that chronic alcohol ingestion was able to modify the integrity of the cells in the rat hard palatine mucosa.

IGFR-I expression and structural analysis of the hard palatine mucosa in an ethanol-drinking rat strain (UChA and UChB)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Interface Formation and Electrical Transport in SnO2:Eu3+/GaAs Heterojunction Deposited by Sol-Gel Dip-Coating and Resistive Evaporation

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Schottky emission in nanoscopically crystallized Ce-doped SnO2 thin films deposited by sol-gel-dip-coating

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Strength of a feldspar ceramic according to the thickness and polymerization mode of the resin cement coating

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Femtosecond laser ablation on dental hard tissues-Analysis of ablated profile near an interface using local effective intensity

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)