Class II. – modifications for amalgam  Conventional preparation  Slot  Large cavities – replacement of the cusp (cusps), combination with the cavity on vestibular/oral surface Occlusal cavity Proximal cavity MOD Cavosurface angle Slight reveres curve Clearence of the proximal surface Retention – grooves in the proximal cavity Divergency of axial walls towards gingiva and Convergency - divergency towards proximal space. Autoretention Slot is a cavity that is open on occlusal surface. It is limited on the proximal ridge Slot preparation Slot for amalgam  Access to the caries lesion - through the enamel wall - breaking out of the enamel lamella - excavation of carious dentin lroubal@med.muni.cz 12 Pre op lroubal@med.muni.cz 13 Access to the cavity Slot for amalgam Autoretention - Grooves - Divergency towards gingiva - Convergency and divergency of axial walls in horizontal plane(towards proximal space) Slot for amalgam  Rule of the gingival wall -1 mm wide -90% angle towards the pulpal wall -outer line beveled if in enamel -horizontal groove Sedelmayer Sedelmayer J. Amalgám – zapomenuté řemeslo. Brno, 2000. Bažant V. Konservační zubní lékařství, SPN Praha,1962. Slot cavity  Limited on proximal ridge  Axial walls are divergent towards gingiva  The proximal box has a typical picture of fish tail  There are grooves: - One horizontal in gingival wall - Two vertical in axial walls Large defects  In vital teeth if the cusp has been undermined due to dental caries  Large defects in non vital teeth – amalgam overlays  Combination with the cavity on vestibular/oral surface Cusp has been removed The thickness of the filling 3 – 4 mm (at the cusp) Retention Grooves, pins, slots Parapulpal pins Intrapulpal posts (root canal posts) Retention in the endodontic cavity Large amalgam restoration - overlays  lroubal@med.muni.cz 25 Amalgam Exact work! lroubal@med.muni.cz 26 Basic modifications Rules for large restorations  Clear and sharp outlines – cavosurface margin Thickness of the amalgam (the cusp 3 – 4 mm)  Autoretention - Grooves - Pins, slots - Parapulpal pins - Intrapulpal posts – root canal posts Resistance – acc to general rules Preparation for adhesive materials – composites  No extension for prevention (adhesion)  No grooves  No undercuts  Rounded box  Bevel the axial walls and the outer edge od the gingival wall  Small isolated cavities are possible Cavity for amalgam Cavity for composite Bevel on the gingival wall Preparation do not bevel!!! Ohlazení zevní hrany gingiválního schůdku mimo sklovinu Bevel of enamel on axial walls Yes No Amalgam Composite material 47 48 Sedelmayer Alternative preparation – adhesive slot Glassionomer and class II.  Temporary filling – first phase for the sandwich technique  Tunnelová filling (preparation) Tunnel preparation 1. Low caries risk 2. Proximal ridge without infrac 3. Good cooperation 4. Small caries lesion 1. Loups or microscope 2. Miniinstruments 3. Dezinffection 4. GIC in capsules 5. BW post op