Development of a new type GIC for dental use and preparing for production
The purpose of this project is to develop a new type of glass-ionomer cement (GIC) for dental use and prepare this filling material for production.
Introduction:
Glass-ionomer cements (GIC) are used in dentistry today. They are available in different colours according to the shades of the natural teeth. GICs are used to fill permanent front teeth and decidious molars. This filling material is inert and does not dissolve substances which is harmful for the human body. GICs are not used in permanent molars because of its britness characteristic. Amalgam and composites are videly used for filling pemanent molars. Both of them release toxic chemicals which is harmful for the host body. Moreover, the mercury containing amalgam exposes the environment. If we have a GIC with good mechanical characteristics, the amalgam fillings would be replaced.
Six thousand amalgam fillings are placed in the patients teeth per year in Hungary. Eight million teeth are restored per year in the UK, and 100 millions per year in the USA. One can easily conclude that if we can offer an alternative to the amalgam as a restorative material, it would not be negligible from the view point of business. The research group contributing this project is ont he right track to develope a competitive restorative material having good mechanical characteristics.
The widely used light cured composite restorative materials does not suit for the requirements. The degradation of aged hybrid layer by the host derived matrix metalloproteases (MMPs) [3] as a consequence of enlargement of the micro leakage. A moiety from the surface of the composit restoration dissolves bisphenol-A into the the saliva [8]. Apart from the public health point of view the amalgam restoration has considerable significance due to its cost effectivity per restoration. Several hundred million amalgam restorations are filled in dental cavities per year all over the word. This huge amount of amalgam significantly compromises the environment because of its mercury content. GICs should be taken into account as a restorative material, however commercially availably GICs are not used for restoration of permanent molars because of their characteristics brittleness. Efforts were made for reinforcement of GICs by inclusion of silver ions with little effect or by filling with resin resulted in an increase of elasticity of the material [12]. The rigid cross-link between the polyacid chain and the filler is responsible for the fracture of the material. Since mechanical properties of a material is decisively determined by the electronic structure, therefore it is important to analyse its electronic structure first when one developes a new formula. A promising approach was reported by Xie et al. [13] and Moshaverinia et al. [10] which is in line with our concept. They incorporated aminoacid derivates between the carboxilic acid groups which made the polyacid backbone more flexible to allowing greater freedom of carboxilic groups to react with Al and Ca ions, resulting in improved filler-polymer interaction – and more complete polysalt bridge formation. This kind of development may resulted in a new restorative material formula, which has biological compatibility [4], it saves the environment and it will be accessible for wide range of the population – replacing the amalgam restorations.
