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polishing
dental material
| Question | Answer |
|---|---|
| cutting | removing material by shearing-off process, results in somewhat smooth surface, accomplished by metal burs and hand instruments-burs usually made of carbon steel or tungsten carbide |
| abrasion | wearing away of a surface, produces irregular grooves or scratches |
| recontouring | reducing areas that are too bulky &/or overextended in order to blend with the normal contours of the tooth that has been restored |
| finishing | process of producing the final shape and contour of a restoration-smooths overal surface of restorations to the tooth |
| polishing | abrasion of a surface to reduce the size of the scratches until the surface appears shiny-high luster |
| abrasive | material doing the wearing or abrading, may be on burs, disks, stones, wheels or strips abrasives may also be mixed with liquids to form a paste or slurry |
| Types of abrasives: chalk | calcium carbonate-teeth, gold, amalgam restorations, plastics |
| Types of abrasives: Pumice | volcanic glass-variety of grits: used in sealant placement: enamel, gold foil, dental amalgam, acrylic denture bases in labs |
| Types of abrasives: sand (quartz) | bonded to paper disks for grinding metals and plastics |
| Types of abrasives: cuttle (quartz) | bonded to paper disks for grinding metals and plastics |
| types of abrasives: garnet | manganese, magnesium, iron, colbalt, aluminum-coated disks for plastics and metal alloys |
| types of abrasives: emery | aka corundum, aluminum oxide-find on arbor bands that attach to a lab lathe for grinding custom trays and acrylic appliances |
| types of abrasives: aluminum oxide | has replaced emery for several uses, disks and strips, rubber wheels and points; adjust enamel finish metal alloys and ceramic materials |
| types of abrasives: silex | quartz -prophy paste-used on teeth in mouth |
| types of abrasives: tin oxide | yucky taste-used for tarnished gold |
| types of abrasives: rouge | iron oxide-polishing agent for gold and noble metal, only used in the lab setting-NOT IN THE MOUTH |
| bonded and coated abrasives used in dentistry: diamond burs | diamond chips bonded to a shaft |
| bonded and coated abrasives used in dentistry: stones | various shapes and sizes |
| bonded and coated abrasives used in dentistry: | rubber wheels or points |
| bonded and coated abrasives used in dentistry: disks or strips | abrasives bonded to pater metal or plastic disks and strips |
| bonded and coated abrasives used in dentistry: powders | used in conjunction with water, alcohol, glycerin, mouthwash, brushes, rubber cups, felt cones or wheels, cloth wheels |
| factors affecting rate of abrasion: hardness | harder abrasive particles=more abrasion: abrasives heat up objects being abrded during use=softens material=increased abrasion |
| factors affecting rate of abrasion: size | larger particles (grit) produce deeper scratches=more abrasion |
| factors affecting rate of abrasion: shape | irregularly shaped particles=more abrasion |
| factors affecting rate of abrasion: pressure | increased pressure=more abrasion |
| factors affecting rate of abrasion:speed | faster=more abrasion |
| factors affecting rate of abrasion: lubrication | water is most used lubricant-paste/slurry |
| why do we polish-reduce adhesions | smooth surface so plaque, stain and calculus won't stick as easily |
| why do we polish- | make surface enamel feel smooth, increase esthetics-shiny |
| why do we polish-reduce corrosion and tarnish | extends lifetime of restorations |
| process of polsihing | when the surface acquires a smooth shiny layer it is considered polished. shiny layer is known as polish: fine scratches are filled in by the finer particulate being removed from the surface-this layer=microcrystalline aka polish layer or Beilby layer |
| rationale for amalgam polishing (we don't do it anymore) | refine anatomy & occlusion, eliminate surface irregularities, eliminate overhangs & undercontoured proximal surfaces-create a smooth shiny surface that is asthetically pleasing |
| contraindications of amalgam polishing | fractures present (in amalgam)-open margins-recurrent decay-less than 24 hrs since plcmt (low copper b/c it must finish setting up)-spherical high copper can be finished in the same apt |
| precautions when amalgam polishing | must maintain centric occlusal contacts(don't alter occlusion): avoid excessive heat-could damage pulp, excess heat brings mercury to the surface of amalgam-WEAKENS RESTORATION AND RELEASES VAPORS |
| determining marginal adequacy | margins of amalgam should be flush with the tooth surface |
| supramarginal restoration w/o overextension | extends straight up |
| supramarginal restoration w/ overextension of amalgam | goes up and over the tooth surface |
| submarginal | below the margin |
| adjusting enamel | use finishing bur to resolve submarginal discrepancy of 0.2mm or less |
| open margin | gap between tooth structure and amalgam |
| overcontoured (or undercarved) | lump in amalagam |
| undercontoured or (overcarved) | too deep, must to it over |
| impregnated rubber points/ cupts system (Shofu) | brownie-greenie-supergreenie |
| margination | process of eliminating submarginal discrepancies |
| what distinguishes the green point and cup from the supergreen? | yellow band on supergreenie |
| when using a bur which way should it be moved | tooth to amalgam |
Created by:
jfgwinn
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