ABRASIVE DISCS

By Dr. Vishaal Bhat on Friday 28 January 2011 with 0 comments



The flexibility of the disk & delicate wiping action of disks produce a smooth contoured surface. Contouring of an irregular surface to produce a smooth flat or convex contour is readily accomplished with a disk than by other methods. Each operator has his own preferences, depending upon his experience. Abrasive discs are available in diamond, silicon carbide, synthetic & natural (emery), Al O, garnet, flint (sand), cuttle, rouge (ferric) &crocus (impure ferric oxide). The backing of the diamond disks is metal. The other abrasives are cemented to flexible backing materials. The disks that cut best are from one of the three materials: Diamond, silicon carbide, Al2O3. The natural abrasives (emery, garnet, cuttle, & Fe oxide) are more suitable for polishing than for cutting.

Al2O3, which is tougher than silicon carbide, is more suitable for very hard materials; also there is a ration between silicon carbide  &steel that dulls the silicon carbide particles. Because alumina reacts with glass, silicon carbide is preferable for abrading porcelain. gold can be cut & polished by Sic ,alumina or garnet .

GARNET:
·         For acrylic resins.
·         Also satisfactory for composites.

CUTTLE:
·         Excellent for cohesive gold
·         Amalgam
·         Imparting polish to gold castings along the marginal areas.
Discs are available in several sizes ranging from ¼² to 7/8² .For sizes ½²diameter or larger, the snap –on type of mounting is desirable. For 3/8 & ¼ diameter, the pinhole disc is used with the screw type mandrel. Screw type mandrel comes in 2 sizes. Selection of the mandrel size should correspond with the size of the disc.

Category: Conservative and Endodontics Notes , Conservative Dentistry Notes , Dental Materials Notes , Endodontics Notes

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