Definujte zápatí – název prezentace nebo pracoviště1 Preclinical dentistry I. Permanent filling materials Permanent filling materials Amalgam Composites Glassionomers Amalgam Amalgam Metal-like restorative material composed of silver-tin-copper alloy and mercury. Particles of the alloy ✓Irregulary shaped (filings - lathe cut) ✓Microsphers ✓Combination of the two. Particles shape High – Copper Amalgam Microsphers of the same composition (unicompositional) Mixture of irregular and spherical particles of different or the same composition (admixed) Production of irregular particles Metal ingrediences heated, protected from oxidation, melted and poured into a mold to form an ingot. Phases of the alloy: (intermetallic compounds) Ag3Sn - g Cu3Sn - e Cu6Sn5 - h Ag4Sn - b Production of irregular particles Ingot cooled slowly Ingot heated at 400°C (6 – 8 hours) (homogeneous distribution of Ag3Sn) Ingot cut on the lathe, particles passed trough a fine sieve and ball milled to form the proper particle size. Aging of particles (60 - 100°C, 6 – 8 hours) Particle size: 60 – 120 mm in length 10 – 70 mm in width 10 – 35 mm in thickness Production of irregular particles Molten alloy is spraying into water under high pressue Irregulary shaped high-copper particles Production of spherical particles Molten alloy is spraying under high pressue of inert gas through a fine crack in a crucible into a large chamber Diameter of the spheres: 2 – 43mm Amalgamation processes Metal alloy is mixed with pure mercury Trituration Types of amalgam restorative materials Low – Copper Amalgam (5% or less copper) conventional amalgam Composition – wt% Silver 63 - 70 % Tin 26 – 28 % Copper 2 - 5% Zinc 0 - 2% Amalgamation processes Hg Sn Sn Sn Sn Sn Ag Ag Ag Ag Ag Cu Cu Cu Cu Cu Ag3Sn – g Cu3Sn – e Intermetallic compounds Amalgamation processes low copper amalgam Sn Sn Sn Sn Sn Ag Ag Ag Ag Ag Cu Cu Cu Cu Cu Ag3Sn – g Cu3Sn – e Sn7Hg – g2 Ag2Hg3 – g1 The mercury disolves the particles of the alloy Sn – Hg: gamma 2 phase g2 Ag-Hg: gamma 1 phase g1 Setting of low copper (conventional) amalgam Principle of setting is crystallization Structure of the amalgam filling Ag-Hg: gamma 1 Sn-Hg: gamma 2 Gamma phase (Ag-Sn) that did not dissolve completely – remains in the structure These phases crystallized – become hard Risks of the gamma 2 phase ̶ Non stable ̶ Tin is released due to electrogalvanism in oral cavity and mercury from this phase reacts with remaining gamma phase. ̶ This is external electrochemical corrosion. Low copper amalgam has worse mechanical and corrosion resistance than high copper amalgam High copper amalgam ̶ Content of copper increased: 12 – 13% (Less tin) ̶ Or up to 25% up to 40% ( Less tin and silver) Better mechanical and corrosion resistance Amalgamation processes – high copper amalgam Sn Sn Sn Sn Sn Ag Ag Ag Ag Ag Cu Cu Cu Cu Cu Ag3Sn – g Cu3Sn – e Cu6Sn5 - h Sn7Hg – g2 Ag2Hg3 – g1 High copper amalgam – copper dissolved in mercury has high reaction afinity to tin that is also dissolved in mercury. It reacts with tin in gamma2 phase g2 and eta phase - h comes into existence. The gamma 2 phase disappears. In amalgams with high content of copper (25% and more) the gamma 2 phase g2 does not occur. Types of amalgam restorative materials High – Copper Amalgam (13% - 40%) Admixed regular: Irregular particles:Ag 40 - 70 Sn 26 – 30 Cu 2-30 Zn 0-2 Spherical particles Ag 46 – 65 Sn 0 – 30 Cu 20 - 40 Types of amalgam restorative materials High – Copper Amalgam (13% - 30%) Copper Admixed unicompositional: Ag 52 - 53 Sn 17 - 18 Cu 29-30 Zn 0 Spherical particles Ag 46 – 65 Sn 0 – 30 Cu 20 – 40 Types of amalgam restorative materials Unicompositional - Spherical Ag 40 – 60 Sn 22 – 30 Cu 13 – 30 Amalgamation processes Sn Sn Sn Sn Sn Ag Ag Ag Ag Ag Cu Cu Cu Cu Cu Ag3Sn – g Cu3Sn – e Cu6Sn5 - h Sn7Hg – g2 Ag2Hg3 – g1 High copper amalgam g2 phase disappears or does not occur depending on the content of copper Gamma two disapears or it does not occur when content of copper is high Amalgam - properties Amalgam ➢Wear and pressure resistance (2mm thickness ast least)- brittleness ➢Easy handling ➢Low price ➢Thermal and electrical conductivity ➢Corrosion ➢Bad aesthetics ➢Flow (deformation of not completely set amalgam if the filling is loaded) ➢Creep – completely set amalgam can be deformed due to bite forces. The filing is principly hammered. Biocompatibility ̶ More than 160 years, more than 200 milions Ag fillings every year in USA. ̶ Allergy rare ̶ Precautions in children and in pregnancy. AMALGAM IS STILL A MATERIAL OF CHOICE Toxicity and environmental risks Organic compounds Vapours, aerosol Precautions ̶ Ventilation ̶ Rests of amalgam in water ̶ Amalgam separators ̶ Dangerous waste (180 110) Amalgam indications ̶ Posterior area ̶ I. a II. class : moderate or large cavities, ̶ V. class Other factores for consideration When oral hygiene is not excellent When patient wants low cost filling. Indications and contraindications of amalgam Indications ̶ Moderate and large cavities in posterior area (class I., II. V) Contraindications Fillings in frontal area Pregnancy, children till the age of 15 Allergy Other factores for consideration When oral hygiene is not excellent When patient wants low cost filling. Mixing of amalgam ➢ Hand mixing (obsolete) ➢Power driven trituration Amalgamators Cup Amalgam gun Condensor Amalgam gun Crucible (cup) Power driven condensation handpiece condensor Instruments ➢Preparation instruments ➢Filling instruments ➢Carvers ➢Burnishers Instruments ➢Preparation instruments - power driven Burs Diamonds Instruments ➢Preparation instruments - hand Chisel Excavator Amalgam carrier Amalgam carrier Condensor with flat front Condensor and burnisher - spatula combined Burnisher - spatula Angular- trough edge trough face Carver - Frahm Carver - Sapin Carver - Sapin Carver Discoid-cleoid Carver discoid-cleoid Burnisher – spatula, angular three face Ball condensor – used as a burnisher at most Principle of the retention of amalgam ̶ Macromechanical retention - Undercuts - Grooves - Cavities for retention Definujte zápatí – název prezentace nebo pracoviště48 Undercut Amalgam step by step procedure ̶ Preparation of the cavity ̶ Base – protection of dentin wound ̶ Mixing ̶ Application portion by portion, condensation ̶ Carving ̶ Burnishing ̶ Finishing and polishing 50