Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 67
Filtrar
Mais filtros











Base de dados
Intervalo de ano de publicação
1.
J Dent Res ; 89(12): 1499-504, 2010 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-20940353

RESUMO

The long-term effectiveness of chlorhexidine as a matrix metalloproteinase (MMP) inhibitor may be compromised when water is incompletely removed during dentin bonding. This study challenged this anti-bond degradation strategy by testing the null hypothesis that wet-bonding with water or ethanol has no effect on the effectiveness of chlorhexidine in preventing hybrid layer degradation over an 18-month period. Acid-etched dentin was bonded under pulpal pressure simulation with Scotchbond MP and Single Bond 2, with water wet-bonding or with a hydrophobic adhesive with ethanol wet-bonding, with or without pre-treatment with chlorhexidine diacetate (CHD). Resin-dentin beams were prepared for bond strength and TEM evaluation after 24 hrs and after aging in artificial saliva for 9 and 18 mos. Bonds made to ethanol-saturated dentin did not change over time with preservation of hybrid layer integrity. Bonds made to CHD pre-treated acid-etched dentin with commercial adhesives with water wet-bonding were preserved after 9 mos but not after 18 mos, with severe hybrid layer degradation. The results led to rejection of the null hypothesis and highlight the concept of biomimetic water replacement from the collagen intrafibrillar compartments as the ultimate goal in extending the longevity of resin-dentin bonds.


Assuntos
Colagem Dentária/métodos , Adesivos Dentinários/química , Etanol/química , Solventes/química , Condicionamento Ácido do Dente , Bis-Fenol A-Glicidil Metacrilato/química , Clorexidina/química , Clorexidina/farmacologia , Colágeno/ultraestrutura , Resinas Compostas/química , Materiais Dentários/química , Análise do Estresse Dentário/instrumentação , Dentina/ultraestrutura , Humanos , Interações Hidrofóbicas e Hidrofílicas , Teste de Materiais , Inibidores de Metaloproteinases de Matriz , Microscopia Eletrônica de Transmissão , Cimentos de Resina/química , Saliva Artificial/química , Estresse Mecânico , Fatores de Tempo , Água/química
2.
Oper Dent ; 34(4): 452-9, 2009.
Artigo em Inglês | MEDLINE | ID: mdl-19678451

RESUMO

This study evaluated the effect of the C-factor and dentin preparation method (DPM) in the bond strength (BS) of a mild self-etch adhesive; the study also observed the SEM superficial aspects of the corresponding smear layer. For purposes of this study, 25 molars (n=5) were used in a bond strength test. The molars were divided into two parts (buccal and lingual): one part received a Class V cavity (C-factor=3) and the other received a flat surface (C-factor=0) with the same bur type (coarse diamond or carbide bur and fine diamond or carbide bur), both within the same dentin depth. Five teeth were prepared with wet 60-grit and 600-grit SiC papers. After restoration with Clearfil SE Bond, microtensile beans (0.8 mm2) were prepared and tested after 24 hours in a universal testing machine (0.5 mm/minute). An additional two teeth for each DPM were prepared for SEM evaluation of the smear layer superficial aspects. The BS values were submitted to one-way ANOVA, considering only the DPM (flat surfaces) and two-way ANOVA (C-Factor x DPM, considering only burs) with p=0.05. Although the DPM in the flat surfaces was not significant, the standard deviations of carbide bur-prepared specimens were markedly lower. The BS was significantly lower in cavities. The fine carbide bur presented the most favorable smear layer aspect. It was concluded that different dentin preparation methods could not prevent the adverse effect in bond strength of a high C-factor. A coarse cut carbide bur should be avoided prior to a mild self-etch adhesive, because it adversely affected bond strength. In contrast, a fine cut carbide bur provided the best combination: high bond strength with low variability, which suggests a more reliable bond strength performance.


Assuntos
Colagem Dentária , Preparo da Cavidade Dentária , Cimentos Dentários , Corrosão Dentária , Análise do Estresse Dentário , Dentina/ultraestrutura , Equipamentos Odontológicos de Alta Rotação , Adesivos Dentinários , Humanos , Técnicas In Vitro , Dente Molar
3.
J Prosthet Dent ; 84(3): 360-3, 2000 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-11005911

RESUMO

STATEMENT OF PROBLEM: The low resistance to corrosion is the major problem related to the use of copper-aluminum alloys. PURPOSE: This in vitro and in vivo study evaluated the corrosion of 2 copper-aluminum alloys (Cu-Al and Cu-Al-Zn) compared with a nickel-chromium alloy. MATERIAL AND METHODS: For the in vitro test, specimens were immersed in the following 3 corrosion solutions: artificial saliva, 0.9% sodium chloride, and 1.0% sodium sulfide. For the in vivo test, specimens were embedded in complete dentures, so that one surface was left exposed. The 3 testing sites were (1) close to the oral mucosa (partial self-cleaning site), (2) surface exposed to the oral cavity (self-cleaning site), and (3) specimen bottom surface exposed to the saliva by means of a tunnel-shaped perforation (non-self-cleaning site). RESULTS: Almost no corrosion occurred with the nickel-chromium alloy, for either the in vitro or in vivo test. On the other hand, the 2 copper-aluminum-based alloys exhibited high corrosion in the sulfide solution. These same alloys also underwent high corrosion in non-self-cleaning sites for the in vivo test, although minimal attack was observed in self-cleaning sites. CONCLUSION: The nickel-chromium alloy presented high resistance to corrosion. Both copper-aluminum alloys showed considerable corrosion in the sulfide solution and clinically in the non-self-cleaning site. However, in self-cleaning sites these 2 alloys did not show substantial corrosion.


Assuntos
Ligas Dentárias/química , Alumínio/química , Ligas de Cromo/química , Cobre/química , Corrosão , Humanos , Saliva , Saliva Artificial , Sulfetos
4.
J Adhes Dent ; 2(3): 209-12, 2000.
Artigo em Inglês | MEDLINE | ID: mdl-11317394

RESUMO

PURPOSE: To evaluate the influence of the method and duration of storage for different types of teeth prior to their use in dentin bonding tests with three adhesive systems. MATERIALS AND METHODS: Recently extracted sound human molars, bovine incisors, and human caries-free molars obtained from exhumed bones 5 years postmortem were used. The latter group of teeth was kept dry for 6 months, and then rehydrated in distilled water over a period of 30 days. The adhesive systems used were Prime&Bond 2.1. Single Bond, and Etch&Prime 3.0. Human teeth were embedded longitudinally in PVC cylinders; bovine incisors were embedded leaving the buccal surface exposed. Flat dentin surfaces were cut with a diamond disk and ground with up to 600-grit SiC paper. Adhesives were applied following manufacturers' instructions. A silicone mold with a cone-shaped perforation (4.5 mm high and 2 mm diameter at the smallest) was fixed on the dentin surface and filled with TPH composite resin. The specimens were stored in distilled water for two weeks before testing. RESULTS: ANOVA did not detect statistical differences either in the main factors (substrate and adhesive system) or in their interaction (p > 0.05). Tensile bond strength averages ranged from 11.6 to 14.2 MPa. The dentinal substrates showed similar performances, regardless of the adhesives tested. CONCLUSION: The differences among the three dentin substrates do not appear to be critical for the tensile bond strength test for the three adhesive systems. The adhesive systems presented similar bond strengths.


Assuntos
Colagem Dentária , Adesivos Dentinários/química , Dentina/ultraestrutura , Análise de Variância , Animais , Bis-Fenol A-Glicidil Metacrilato/química , Cadáver , Bovinos , Resinas Compostas/química , Dessecação , Difosfatos/química , Etanol/química , Humanos , Teste de Materiais , Metacrilatos/química , Ácidos Polimetacrílicos/química , Resistência à Tração , Extração Dentária , Água
5.
Rev Odontol Univ Sao Paulo ; 4(4): 278-83, 1990.
Artigo em Português | MEDLINE | ID: mdl-2135439

RESUMO

Research was carried out with the objective of studying the clinical influence of dental plaque disclosing agents as motivators for patients oral hygiene. Methylene blue, basic fuchsin, Bismark brown, malachite green, and gentian violet were used for dental plaque disclosure. Five groups were evaluated, 12 patients each, besides a control group of 12 patients. The experimental period analysed statistically was of approximately 7 weeks. The statistical analysis of the results proved not to have significant differences among the 6 groups analysed.


Assuntos
Corantes , Placa Dentária/diagnóstico , Placa Dentária/prevenção & controle , Motivação , Higiene Bucal , Análise de Variância , Placa Dentária/microbiologia , Índice de Placa Dentária , Educação em Saúde Bucal , Humanos , Indicadores e Reagentes
6.
Rev Odontol Univ Sao Paulo ; 4(4): 270-2, 1990.
Artigo em Português | MEDLINE | ID: mdl-2135437

RESUMO

The purpose of this investigation was to verify the influence of ventings on the reproduction of interocclusal contacts from the wax pattern to the cast crown and also to note the influence on surface quality. Comparatively were performed tests with no venting, with one joined on the outside of the full crown wax pattern and two ventings joined on the sprues (Fig. 2). The castings were obtained with a nickel-chrome alloy and investing was performed with phosphate bonded investment. From the results it was possible to conclude: casting without venting presented higher frequency of no reproduction of interocclusal contact points; when using one venting, joined on the outside of the crown wax pattern, the reproduction of the interocclusal contacts was 100%, the venting did not lead to high improvement on the surface quality.


Assuntos
Coroas , Técnica de Fundição Odontológica , Ligas de Cromo , Oclusão Dentária , Humanos , Propriedades de Superfície
7.
Rev Odontol Univ Sao Paulo ; 4(3): 197-9, 1990.
Artigo em Português | MEDLINE | ID: mdl-2135423

RESUMO

The purpose of this work was investigate the consistency of three zinc oxide-eugenol impression pastes, considering its flow. Flow tests were performed based on the AMERICAN DENTAL ASSOCIATION-Specification no 16. Setting time was based at that one when should be applied the load to get considered disc diameter; the values were obtained graphically. Considering the results it was possible to conclude: a) the first two materials (Equalizing and Horus) present high initial flow, which however drops down earlier on the second one; b) both materials may be used with non compressive impression technic but the second one has shorter working time; c) the third material (Lysanda) as it presents lower flow and faster setting time, may be used with compressive impression technic.


Assuntos
Materiais para Moldagem Odontológica/química , Cimento de Óxido de Zinco e Eugenol/química , Viscosidade
8.
Rev Odontol Univ Sao Paulo ; 3(4): 481-4, 1989.
Artigo em Português | MEDLINE | ID: mdl-2577467

RESUMO

This is the third part of a research about a low gold content alloy (Au 46%, Pd 4%, Ag 40%, Cu and Zn), involving the study of soldered joints. Transverse test was used to evaluate mechanical resistance of bars joined by soldering. Comparativily were considered the following "soldering" condution: entire bars without investing and without soldering; entire bars with investing and without soldering but simulating thermal cycle and quenched in water after one and five minutes; with investing, soldering and quenched in water after one and five minutes. Of the "soldered" alloy were obtained also Brinell and Vickers hardness numbers. Corrosion resistance test was performed for six month at vapors of acetic acid solution, saturated with hydrogen sulfide. From the results it was possible to conclude: the soldered joints of the alloy reach good corrosion resistance; the soldered joints do not become brittle; thermal cycling as elapsed from soldering procedure and water quenched after five minutes increases the strength of the alloy and the soldered joints.


Assuntos
Soldagem em Odontologia , Ligas de Ouro , Corrosão , Dureza
9.
Rev Odontol Univ Sao Paulo ; 3(3): 390-3, 1989.
Artigo em Português | MEDLINE | ID: mdl-2490838

RESUMO

The research presents some properties of a low gold content (46%) alloy. Mechanical properties were performed with specimens submitted to several treatment; as cast; hardened at 400 degrees C/15 min; softened at 700 degrees C/10 min; and hardened after softening. Melting temperature was considered when the alloy become a liquid sphere. Casting shrinkage determination was based on the method presented by EARNSHAW. Density was obtained by the weight of polished specimens in and out of water. Corrosion was tested at vapors of acetic acid solution, saturated with hydrogen sulfide, for a period of six months. Cost was computed on base of materials cost and density of alloy. The results showed: tensile strength and proportional limit are very high, specially when hardened and the alloy may be used for large bridges; elongation is low when alloy was heat hardened, but is good when in the as cast condition; the alloy may be handled with conventional materials and equipment; corrosion resistance is excellent; final cost is a little higher than half that of conventional gold alloy.


Assuntos
Ligas de Ouro/química , Corrosão , Custos e Análise de Custo , Técnica de Fundição Odontológica , Temperatura Alta , Teste de Materiais , Resistência à Tração
10.
Rev Odontol Univ Sao Paulo ; 3(2): 345-53, 1989.
Artigo em Português | MEDLINE | ID: mdl-2639456

RESUMO

We analyzed the possible percentage variations of dentinal penetration of the methylene blue solution in the apical third, in human teeth pulled out, after it's preparation, utilizing files type K-Flex, and five auxiliary chemical substances. Results have shown that there is a significant difference among the percentage of the dye penetration and among the auxiliary chemical substances used for the chemical-mechanic preparation. We can also prove true that, for apical region, the Endo PTC was the one that showed the greatest percentage of penetration.


Assuntos
Permeabilidade da Dentina/efeitos dos fármacos , Irrigantes do Canal Radicular/farmacologia , Permeabilidade Dentária/efeitos dos fármacos , Infiltração Dentária , Humanos , Raiz Dentária
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA