Adobe Systems Faculty of medicine, Dpt of restorative dentistry, ass.prof. L. Roubalikova 1 Restorative dentistry 3rd year Lecture 2 Glassionomers Adobe Systems Glassionomers Materials that have been developed by Wilson and Kent was a product of an acid-base reaction between basic fluoraluminosilicate glass powder and polycarboxylic acid. Glassionomer cement is a water based materiál that herdens following the acid-base reaction between this glass and aqueous solution of polyacid. [USEMAP] Adobe Systems Glassionomers contain metals Aluminium ̶Calcium ̶Strontium ̶Zinc ̶Sodium ̶Potassium ̶Lanthanum Definujte zápatí – název prezentace nebo pracoviště 3 [USEMAP] Adobe Systems Phosphates and fluorides ̶Are used to decrease the melting temperature in the production process and are incorporated to the glass composition to modify the setting characteristics. ̶ Definujte zápatí – název prezentace nebo pracoviště 4 [USEMAP] Adobe Systems X-ray contrast - radioopacity ̶Lanthanum oxide, strontium oxide (incororated into the glass) ̶Baryum sulphate ̶ Definujte zápatí – název prezentace nebo pracoviště 5 [USEMAP] Adobe Systems Essential ingredients of the glass are aluminiumoxide and silicium dioxide Definujte zápatí – název prezentace nebo pracoviště 6 [USEMAP] Adobe Systems Liquid of glassionomers ̶Liquid is based on polycarboxylic acid: Polyacrylic acid Polymaleic acid Acrylic acid- itaconic acid copolymer Acrylic acid- maleic acid copolymer and others. Water, tartaric acid (acelerator) Definujte zápatí – název prezentace nebo pracoviště 7 [USEMAP] Adobe Systems Acids can be a component of powder also ̶Freeze dried powder ̶ These cements are mixed with water or with the polycarboxylic acid. Definujte zápatí – název prezentace nebo pracoviště 8 [USEMAP] Adobe Systems Glassionomers ̶Principle of setting – acid base reaction 1.Hydrogen ions of the acid attack the glass particles in the presence of water, releasing calcium, strontium and aluminíum ions 2.The metal ions react with the carboxylic acid groups to form the polyacidsalts matrix. The glass surface is changed to a silica hydrogel. Glass core remain intact. [USEMAP] Adobe Systems Glassionomers The structure of the cement is a network of polyacid salts. Inside this network remain particles of glass (silica hydrogel on the surface). The setting time is long (days – months) [USEMAP] Adobe Systems Glassionomers - characteristics ̶Chemical bonding to hard dental tissues (carboxy groups react with calcium in hard dental tissues) ̶Thermal expansion similar to dentin ̶Realease fluoride ions (cumulative releasing) ̶ Mechanical not strong enough Aesthetics acceptable ̶ [USEMAP] Adobe Systems ̶Conventional glassionomers for direct restorations ̶Metal reinforced glassionomers ̶Highly viscous glassionomers Low viscosity glassionomers ̶ Base and liners ̶Luting ̶Sealers ̶ Conventional glassionomers Types of glassionomers [USEMAP] Adobe Systems These cements were designed to produce favorable physical properties similar to composite materials. The water solubile resin component has been added into an aqueous solutions of polyacrylic acid. Liquid: polycarboxylic acid, water and 2-hydroxyethylmethacrylate (HEMA). In some materials pendant methacrylate groups are on polycarbocylic acid. Resin modified glassionomers Types of glassionomers [USEMAP] Adobe Systems Two setting reactions: -acid-base reaction -polymerization Resin modified glassionomers Types of glassionomers [USEMAP] Adobe Systems - Significantly less sensitivity to water -Improved mechanical properties -Higher translucency Resin modified glassionomers - benefits Types of glassionomers Adobe Systems Restorative materials Base and liners Luting Orthodontic cementing material Resin modified glassionomers Types of glassionomers [USEMAP] Adobe Systems Glassionomers acc to curing ̶Acid – base reaction ̶ ̶Dual cured glassionomers (resin modified) ̶ ̶ [USEMAP] dentin [USEMAP] water [USEMAP] [USEMAP] [USEMAP] Adobe Systems Glassionomers - indications Fillings Class V. Class III. Class I. and II. in primary dentition Base – sandwich filling Sealants Surface protection Internal mineralization Other indications Endodontic sealers Luting materials [USEMAP] Adobe Systems Glassionomers - contraindications Haevy occlusal stress: Class I. and II. in permanent dentition Class IV. Restoration Caries pulape proxima or open dental pulp [USEMAP] Adobe Systems Mixing Hand Power driven – capsulated [USEMAP] Adobe Systems Hand and power driven mixing of the GIC Obsah obrázku text, bílá tabule Popis byl vytvořen automaticky Definujte zápatí – název prezentace nebo pracoviště 26 Obsah obrázku text Popis byl vytvořen automaticky Obsah obrázku papírnictví, sešívačka Popis byl vytvořen automaticky Forceps for activation and application Obsah obrázku nástroj, stůl Popis byl vytvořen automaticky Mixing machine [USEMAP] Adobe Systems Making filling ̶Preparation ̶Smoth bordes ̶Limited on caries lesion only ̶Conditioning (25% polyacrylic acid 20s´) ̶Washing ̶Filling in one block ̶Varnish after setting ̶Polishing in next appointment [USEMAP] vychstav5tr kavita5tr svobodova po tydnu [USEMAP]