Chapter 11 Terms Flashcards
what are abrasives?
A sharp, hard, natural or synthetic substance used for grinding, finishing, or polishing a softer surface.
what is air particle abrasion?
Process of removing material, contaminants, stain, or carious tissue by use of air pressure and abrasive particles appropriate for the substrate being treated.
what if buffing?
Process of producing a lustrous surface through the abrading action of fine abrasives bound to a nonabrasive carrier with or without a liquid or paste medium.
what is bulk reduction?
Process of removing excess material (natural tooth or synthetic structure) by cutting or grinding with rotary instruments to provide a desired anatomic form.
what is contouring?
Process of producing a desired anatomic form by cutting or grinding away excess material.
what is cutting?
Process of removing material from the substrate by use of a bladed bur or an abrasive embedded in a binding matrix on a bur or disc.
define finished and polished resto
A prosthesis or direct restoration whose outer surface has been progressively refined to a desired state of surface finish.
what is finishing?
Process of removing surface defects or scratches created during the contouring process through the use of cutting or grinding instruments or both.
-step wise process
what is a glazed ceramic?
A specially formulated ceramic powder that, when mixed with a liquid, applied to a ceramic surface, and heated to an appropriate temperature for a sufficient time, forms a smooth glassy layer on a dental ceramic surface (see natural glaze).
define grinding?
Process of removing material from a substrate by abrasion with relatively coarse particles.
define natural glaze
vitrified layer that forms on the surface of a dental ceramic containing a glass phase when the ceramic is heated to a glazing temperature for a specified time.
define overglaze
Thin surface coating of glass formed by fusing a thin layer of glass powder that becomes a viscous liquid at a lower temperature than that associated with the ceramic substrate.
define polish
Luster or gloss produced on a finished surface.
–want it to mimic enamel in the cases of ceramic, composite, porcelain, etc
define polishing
Process of providing luster or gloss on a material surface.
cannot use the same type of abrasive for different kinds of material (e.g. amalgam, ceramics, gold)
ye
In summary, dental abrasives are used for tooth cleaning (dental prophylaxis), occlusal adjustment of tooth enamel and restoration surfaces, contouring of material (acrylic, composite, metal, and ceramic) surfaces, nishing and debris removal (grinding and air-particle abrasion), and ne pol- ishing to produce glossy surfaces
ye
Finished and polished restorations provide four bene ts of dental care: better gingival health, chewing e ciency, patient comfort, and esthetics, reduces tarnish and corrosion, reduces wear rates of opposing teeth, increases strength (rough surface = stress conc)
ye
Smoother sur- faces have less retention areas and are easier to maintain in a hygienic state when preventive oral home care is practiced because dental oss and the toothbrush bristles can gain more complete access to all surfaces and marginal areas.
ye
flutes on burs go up for cutting, contouring, then finishing
ye
what is silicosis?
grinder’s disease; continuous inhalation of grinding aerosols;
debilitating lung disease, fibrosis of alveoli, inhibit air exchange
abrasion is a type of wear–two surface gliding past each other
ye
Erosive wear is caused by hard particles impacting a substrate surface, carried by either a stream of liquid or a stream of air, as occurs in sandblasting a surface.
HOWEVER Chemical erosion, more commonly called acid etching in dentistry, is not used as a method of finishing dental materials
As stated previously, the inherent strength of cutting blades or abrasive particles on a dental instrument must be great enough to remove particles of substrate material without becoming dull or fracturing too rapidly.
ye
Mohs, Knoop, and Vicker’s hardness
ye
what is truing?
Truing is a procedure by which the abra- sive instrument is run against a harder abrasive block until the abrasive instrument rotates in the handpiece without eccentricity or runout when placed on the substrate
what is dressing and what does it do?
e dressing procedure, like truing, is used to shape the instru- ment, but it accomplishes two di erent purposes as well. First, the dressing procedure reduces the instrument to its correct working size and shape. Second, it is used to remove clogged debris from the abrasive instrument to restore grind- ing e ciency during the nishing operation.
what are nonbonded abrasives?
gel, pastes, etc
Dental composites are among the most difficult types of materials to predictably nish and polish to a high luster because they contain a relatively so resin matrix and hard ller particles in their structures.
ye
