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biomaterials

Teeth preserved

New cements and odontological membranes are making restorations and implants cheaper

Two new biomaterials for use in dentistry are promising to bring great benefits for dentists and their patients. The first of them is a flexible film (or membrane) used to assist in the process of fixing the pins used in dental implants. The other is an odontological cement that restores teeth and fixes prosthetic devices, such as pins, crowns and brackets (metal parts for fixing) of orthodontic appliances, used to correct the position of the teeth. The biomaterials, capable of stimulating the regenerative capacity of human tissues, were developed by the Biomaterials Group of the Chemistry Institute at the São Paulo State University (IQ/Unesp), at the Araraquara campus, which is a part of the Multidisciplinary Center for the Development of Ceramic Materials, one of FAPESP’s ten Research, Innovation and Diffusion Centers (Cepids).

Among the advantages of the new products is the use of national technology that will make it possible to place on market materials that are cheaper, compared with the products used nowadays. The flexible film, developed by Rossano Gimenes, who is studying for a doctorate in chemistry, is a compound made up by a conjunction of two polymers (a copolymer) PVDF-TrFe (copolymer of vinylidene fluoride&trifluoroethylene) and barium titanate (BT) ceramic. There are polymer membranes (Teflon, for example) available in the market, used to line bone cavities in the mouth (from extracted teeth, implants, surgery), with a view to protecting the blood clot that forms in the place.

“This clot has a fundamental role in the regeneration of the bone and in the interaction between the pin and the bone. It is what supplies the necessary nutrients for the growth of the bone cells”, explains chemist Maria Aparecida Zaghete, who is Gimenes’ supervisor and the coordinator of the Biomaterials Group. Without this protection, for example, every time a person brushed his teeth, the clot is involuntarily removed, delaying the process of a cure.

Besides its protective function, the membrane developed at Unesp should also speed up bone growth, because of the piezoelectric interactions between the compound and the bone. Piezoelectricity is a physical phenomenon in which certain materials submitted to a mechanical pressure respond with the generation of electric charges. Bones have this characteristic and their growth is associated with piezoelectricity. “With the use of this membrane, we are giving a hand for the bone to regenerate itself more rapidly”, Gimenes explains. Today, similar materials at the disposal of dentists, like the Teflon membranes, only have the function of isolating the clot. They are membranes that do not contribute towards the regeneration of the bone.

The trick for making Unesp’s compound lay in the creation of a ceramic with morphological characteristics capable of multiplying the piezoelectric capacity of the PVDF-TrFe, sold by the chemical industry in the form of pellets and used in a wide variety of applications in the electronics industry, such as hydrophones (a detector of underwater sound signals), acoustic filters and temperature and pressure sensors. In the manufacture of the film, the pellets are dissolved by an organic solvent, and the resulting solution is mixed with the ceramic powder developed by Gimenes, with the assistance of his student Luciane de Oliveira Coelho.

“We carried out tests on rabbit tibias, in vitro and in vivo , which proved the biocompatibility and bioactivity of the compounds, that is, they do not cause any inflammation and they cure lesions to the bone. In the next two years, we will be perfecting the compound and afterwards we will set out for a clinical analysis in institutes and dentistry faculties”, says the researcher. Confident of the viability and of the success of the membrane, Gimenes plans to make the product commercially viable, in the first moment, by means of the creation of a specific company. “I believe that the end product can arrive on the market with a price that is lower than that of the Teflon membranes available today.”

Glass cement
The other material produced by the Materials Group at IQ-Unesp is an ionomer cement, a compound made up of glass particles and an organic acid. The main difference when compared with the similar products to be found in the market lies in the process for preparing it. The majority of cement powders is imported, and the glass used in their manufacture undergoes a fusion of oxides, while at Unesp these products are produced in a chemical process with salts that are soluble in water.

The composition of the cement was also altered with the introduction of a new element, niobium. “We want to develop an end product with better characteristics than the traditional ones”, explains Professor Maria Aparecida, who is supervising Márcio Bertolini, who is studying for a doctorate and conceived the new biomaterial. “Niobium improves the chemical resistance of the ionomer, preventing the cement from being degraded by the alterations in pH in the mouth.

Furthermore, the niobium works to improve the mechanical properties”, the researcher says. “Another advantage of our glass is that we have a better control over the microstructure, making possible a product of a better quality. As we use lower temperatures, the costs of energy in the production of the glass are lower, besides which we use cheaper equipment”, Bertolini explains.

The researchers’ expectation is that the product will be finalized within one year. “At the moment, we are improving the processing of the materials and the morphological characteristics of the glass. Then we will set off for the testing stage, which will be carried out in dentistry colleges “, says Bertolini. Although the main application of this cement is the fixing of pins and prosthetic parts, it may also be used as an ingredient to add more resistance and make other dental resins cheaper.

The project
Flexible Film and Cement for Odontological Use; Modality Research by the Multidisciplinary Center for the Development of Ceramic Materials (CMDMC-Cepid); Coordinator Maria Aparecida Zaghete – Chemistry Institute at Unesp Araraquara; Investment R$ 80,000.00 and US$ 15,000.00

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