Comparative characteristics of the chemical structure of ormokers and traditional composites

This article presents a review of the advantages of using ormokers rather than composite filling material from a chemical point of view. Ormokers are a modified type of hybrid organo-inorganic dental material. They were developed to reduce the shrinkage of filling material from polymerization, improve edge adaptation and abrasion resistance, and increase biocompatibility (compared to composites). The new matrix is based on inorganic polymers, which are polycondensed siloxanes (triblock copolymers). The formation of an inorganic chain of molecules occurs by hydrolysis and polycondensation of Si(OR) groups. Unstable organosilanols are formed from chlorine-containing silanes, as at least two hydroxyl groups are associated with one carbon atom. Such compounds do not exist, as they are rapidly isomerized to form carbonyl compounds (aldehydes and ketones). The resulting organosilanols are then oligomerized to form polysiloxanes with polymerized groups. The basis for the production of ormokers is the sol-gel process. The classical approach involves the formation of an inorganic grid by hydrolysis and condensation of a monomeric organic alkoxy compound followed by crosslinking of the introduced reactive groups (e.g., ultraviolet polymerization). The traditional synthesis of ormokers begins with the finding that alkoxysilanes are functionalized by metal alkoxides to form Si-O-Si nanostructures. One of the metals that functionalizes alkoxysilanes is titanium. In addition to titanium alkoxide, zirconium- or aluminum-alkoxides can be used. These oligomers replace traditional methacrylic monomers in composites. Composite filling materials available today based on the ormoker technology are not pure ormoker systems. Traditional methacrylate monomers-diluents are used to regulate the viscosity of the condensate, which does not improve biocompatibility. The presence of an amide group in the structure of the ormoker increases their biocompatibility with protein compounds in dental tissues.