A review of glass ionomer restorations in the primary dentition.
Glass ionomer cements are tooth-coloured materials that bond chemically to dental hard tissues and release fluoride for a relatively long period. They have therefore been suggested as the materials of choice for the restoration of carious primary teeth. However, the clinical performance of conventional and metal-reinforced glass ionomer restorations in primary molars is disappointing. And although the handling and physical properties of the resin-modified materials are better than their predecessors, more clinical studies are required to confirm their efficacy in the restoration of primary molars. (+info)
Ultraconservative resin restorations.
Ultraconservative dentistry represents a great step forward for the dentist, the profession, and especially the patient. It involves the early detection and complete elimination of all accessible and non-accessible carious material from the tooth. Untreated caries can be extremely and rapidly destructive. The earliest interception of decay maintains total dental health and increases the likelihood of the restored teeth lasting a lifetime. (+info)
Resistance to mercury and antimicrobial agents in Streptococcus mutans isolates from human subjects in relation to exposure to dental amalgam fillings.
Resistance to cefuroxime, penicillin, tetracycline, and mercury is reported for 839 Streptococcus mutans isolates from 209 human study subjects. The MICs of these drugs did not differ for isolates from one dental amalgam group and two nonamalgam subsets: a group with no known exposure to amalgam and a group whose members had their amalgam fillings removed. (+info)
The oral effects of smokeless tobacco.
Smokeless tobacco use has increased rapidly in North America. This form of tobacco use has many oral effects including leukoplakia, oral cancer, loss of periodontal support (recession), and staining of teeth and composite restorations. Systemic effects such as nicotine dependence, transient hypertension and cardiovascular disease may also result from smokeless tobacco use. This paper aims to guide dental practitioners in identifying oral lesions that occur due to the use of smokeless tobacco and also offer guidelines on how to counsel patients who express a desire to stop using smokeless tobacco products. (+info)
Development of metal-resin composite restorative material. Part 2. Effects of acid and heat treatments of silver-tin filler particles on flexural properties of metal-resin composite.
The effects of acid and heat treatments of silver-tin filler particles on the flexural properties of metal-resin composite restorative materials were investigated. Five metal-resin composite restorative materials containing different silver-tin filler particles treated under different conditions were experimentally prepared. The conditions of the alloy particles were; 1) as atomized (NT), 2) 1.8% HCl acid-treated (AT), 3) heat-treated at 150 degrees C for 5 min after AT (A15), 4) heat-treated at 200 degrees C for 5 min after AT (A20) and 5) heat-treated at 250 degrees C for 5 min after AT (A25). The flexural strength and the flexural modulus of elasticity were measured for the five metal-resin composites to evaluate the effects of the acid and heat treatments. The flexural strength of the prepared composites was significantly influenced by the surface condition of the filler particles (p < 0.01), and increased significantly when the as atomized particles (NT) were acid-treated (AT) or acid- and heat-treated at 150 degrees C (A15), but then significantly decreased as the heat treatment temperature increased (A20 and A25). The strength of the A15 composite was significantly higher than those of the other composites, and exceeded that (about 60 MPa) of the previous composite with no treatment. No significant difference was found in the flexural modulus of the composites. (+info)
Metal-resin composite restorative material using powder-liquid system.
In order to further improve the mechanical properties of a metal-resin composite and avoid the problems which were found in the previous metal-resin composite using a 2-paste system, another type of metal-resin composite using a powder-liquid system was developed. In the new system 4-META treatment was carried out at low temperature and DMPT was separated from the 4-META treated particles. The efficacy of this system as well as the effects of 4-META concentration, duration of 4-META treatment (immersion time) and filler content on the flexural properties, working time and setting time were investigated. The flexural strength of the powder-liquid composite was significantly affected by two main factors, immersion time and filler content, and the other properties (flexural modulus, working time and setting time) were by all three main factors. The highest flexural strength of the prepared composite was 91.8 MPa, which was higher than that of the 2-paste composite (64.0 MPa) by about 43%. This was achieved at a 0.1 ratio of 4-META concentration, 30 s immersion time and 94 mass% filler content. The working time and setting time ranged between 2.3-13.6 min and 4.2-20.1 min, respectively, and those of the highest strength composite were 3.0 and 5.2, respectively. The results of the present study indicate that the powder-liquid system is effective to improve the properties of the metal-resin composite. (+info)
Development of metal-resin composite restorative materia. Part 1. Experimental composite using silver-tin alloy as filler and 4-META as coupling agent.
Metal-resin composites, using metal particles instead of inorganic particles as the filler and 4-META as the coupling agent, were experimentally prepared under 20 different conditions (five different concentrations of 4-META, and four different contents of metal particles). The flexural strength of the prepared metal-resin composites was in the range of about 14.5-61.3 MPa. The flexural strength was significantly influenced by the 4-META concentration, the metal particle content and their interaction. The highest strength was estimated at 2-3 mass% of 4-META concentration and 92.0-93.5 mass% metal filler content. The flexural modulus of the metal resin composite ranged approximately from 7.8 GPa to 15.5 GPa. The flexural modulus of the metal resin composite significantly increased with the metal particle content. The effect of the 4-META concentration on the flexural modulus was not significant. (+info)
The influence of configuration factors on cavity adaptation in compomer restorations.
The effect of configuration factor (C-factor) on cavity adaptation was investigated in three compomer and one resin composite restorations. Eighty-four cylindrical dentin cavities (C-factor: approximately 2.5, 3.0 or 4.0) prepared on flat coronal dentin surfaces were filled with the materials in combination with their proprietary adhesive systems. Cavity adaptation was microscopically examined after 15 minutes storage in water at the top surface and at other four sites along the cavity walls. Additionally, indentation testing was performed for each material at 20 minutes and 24 hours after irradiation. Regression analysis revealed no relationship between C-factor and gap dimension in compomer restorations at any of the measuring sites, while a logarithmic relation was found only at the cavity floor of the composite fillings. All materials showed maturation of mechanical properties. The elastic component of the indentation was smaller in compomers than in the composite. It was concluded that C-factor had no influence on the cavity adaptation for compomer restorations. This might be due to reduced stress generation at the bonding interface caused by relatively low mechanical properties immediately after curing, less elasticity, and water absorption in compomers. (+info)