Quantitative analysis of potentially toxic metals in alginates for dental use

Alginate is one the materials most employed in practice to make dental impressions. Substances like zinc, cadmium and lead silicate, which are included in several alginate brands with the aim of improving their physical, chemical and mechanical properties, are a source of serious concern as regards their toxicity. The most serious chronic effect of oral exposure to cadmium is renal toxicity. Assimilation of lead has deleterious effects on the gastrointestinal tract, hematopoietic system, cardiovascular system, central and peripheral nervous systems, kidneys, immune system, and reproductive system. Chronic oral exposures to zinc have resulted in hypochromic and microcyte anemia in some individuals. The aim of the present study was to measure the cadmium, lead and zinc contents of seven brands of alginate for dental use on sale in Brazil. The samples were weighed and placed in the Teflon cups of a closed-system microwave oven. Aqua regia (4mL concentrated HCI:HNO3, 3:1 v/v) and hydrofluoric acid (2mL concentrated HF) were added to the samples, which were then subjected to heating. The samples were then cooled to room temperature and diluted to 25 mL in deionized water in a volumetric glass flask. The samples were diluted in duplicate and analyzed against a reagent blank. The analyses were performed in an atomic absorption flame spectrophotometer. Neither lead nor cadmium was detected. Zinc contents ranged from 0.001% to 1.36% by weight. The alginates exhibited low contents of the metals under study and gave no cause for concern regarding toxicity; even so, it is advisable to monitor potentially toxic materials continually and to analyze their plasmatic levels in the professionals working with them.

A metodologia de superfície de resposta como ferramenta para a avaliação da produção de alginato e poli-hidroxibutirato pela Azotobacter vinelandii

The response surface methodology as a tool for assessing the production of alginate and polyhydroxybutirate by Azotobacter vinelandii. Alginate is a polysaccharide extracted from cell walls of brown algae and used in the food, pharmaceuticals and biotech industries. Production is concentrated on the cultivation of brown seaweed, but several bacteria of the genus Pseudomonas and Azotobacter produce alginate. The chemical structure of alginates produced by algae is similar to those synthesized by A. vinelandii. The bacteria also produce intracellular polymers such as polyhydroxybutyrate (PHB), known as bioplastic. This work studied the simultaneous alginate and PHB production by A. vinelandii using sucrose and different parameters of fermentation in an orbital shaker. The optimal values for the production of these compounds were determined by the MSR. The first experiment was a 2(6-2) factorial design. The second was based on significant variables of the first, resulting in a full 3(3-0) factorial design. From the first to the second, an increase was observed in the PHB productivity from 12 to 45 mg g(-1) cell h(-1) and alginate from 100 to 1,600 mg g(-1) of cell h(-1). The productivity of both compounds was in the maximum incubation temperature of 62 degrees C, in the shortest time of incubation (18h) and the sucrose concentration, 11 g L(-1). In both experiments the PHB extracted presented purity of 94%.

Análise quantitativa de fluoretos nos alginatos para uso odontológico

In this study, the aim was to measure the concentration of fluoride ions in dental alginates and the quantity released from alginate molds immersed in milliQ water, 0.1N hydrochloric acid and artificial saliva. Two separate lots of each of seven brands of alginate commercially available in Brazil were analyzed: Avagel, Deguprint, Hydrogum, Orthoprint, Jeltrate, Jeltrate Plus and Jeltrate Chromatic. Fluoride was measured in each sample by direct potentiometry, using the combined fluoride-ion selective electrode. The brands with the highest fluoride concentrations were Hydrogum (7052.87 μg/g), Jeltrate Plus (6519.68 μg/g) and Orthoprint (6218.18 μg/g). Only in Hydrogum and Jeltrate were different fluoride concentrations found in lots one and two. The various materials showed differences in the amount of fluoride released from the molds into the immersion medium, the mean concentration being highest in Hydrogum and Orthoprint, in all three media. The immersion medium also influenced the release of fluoride, which was lower in saliva than in water and highest in acid. Considering that the concentrations of fluoride found in the alginates tested were high and that various sources of exposure to fluoride exist, there is a need for constant monitoring of alginates intended for dental use.

Potencial tóxico dos alginatos para uso odontológico

Alginate or irreversible hydrocolloid is one the most accepted and frequently employed impression materials in dental practice. Substances like zinc, cadmium, lead silicate and fluorides, which are included in several alginate brands with the aim of improving their physical, chemical and mechanical properties, are a source of serious concern as regards their toxicity. Some brands of alginate have been reported to contain potentially toxic fluorides and metals such as cadmium, lead and zinc silicates, either singly or combined. Consequently, special care should be taken while preparing of these materials. It is necessary to monitor potentially toxic chemicals and metals in the alginates continually to avoid contamination of dental professionals and patients. In this review, alginates used in dentistry are analyzed for potential toxicity.

Imobilização da enzima álcool desidrogenase em suportes alginato-quitosana e glioxil-agarose

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Compatibilidade entre alginato e gesso ortodônticos: capacidade de umedecimento sob influência da desinfecção do molde

The dental trade has offered dental impression and dental stone for orthodontic use ensuring accurate models. The compatibility between these materials is defined by the wetting of the model surfaces by the mixture water/stone poured over it and the influenced by the method of disinfection of model and disinfectant solution used. It was evaluated the influence of spray disinfection with sodium hypochlorite 1% on the wettability of two commercial alginate (Jeltrate ® - Dentsply and Orthoprint ® - Zhermack) at two commercial type III gypsum (Rio ® - ME and AOBussoli Orthogesso Orthogesso ®-SA). Twenty models were fabricated for each type of alginate, which were divided into two groups (water and sodium hypochlorite), receiving respectively water and sodium hypochlorite 1% spray. Each group of models was then further divided into two subgroups, and on their surface were poured 2 ml of type III gypsum (Gesso Rio® or Orthogesso®). Reached the final setting of the gypsum specimens were sectioned vertically and medially, settled water with sandpaper No. 400 and mounted on suitable device for reading (in the right and left) of the contact angle Carl Zeiss microscope (precision, 001). The results were submitted to ANOVA and founded statistical significance for solutions used. It was concluded that sodium hypochlorite spray improved wettability of alginates studied.