Week 5 Carving, Polishing, etc Flashcards
Polishing
involves the abrasion of a surface by an abrasive agent that is harder than the surface being abraded, or polished. The process of abrading the surface to reduce size of scratches and irregularities.
Cutting
removing material by a shearing off process
Abrasion
wearing away of a surface.
Finishing
producing the final shape and contour of a
restoration.
Abrasive
material used to wearing way a surface.
Tribology
science of interacting surfaces in motion. Principles of friction, lubrication, and wear.
Types of abrasives
▪Chalk
▪Pumice
▪Sand
▪Cuttle
▪Garnet
▪Emery
▪Silex
▪Tin oxide ▪Aluminum oxide
Bonded and Coated Abrasives
▪Diamond burs
▪Stones
▪Rubber wheels or points ▪Rubber cups
▪Disks or strips ▪Powders
Factors Affecting the Rate of Abrasion
▪Hardness ▪Size ▪Shape ▪Pressure ▪Speed ▪Lubrication
▪Care needs to be taken with softer materials and abrasive agents.
Why polish
▪To reduce adhesion
▪To make the surface feel smooth ▪To increase esthetics
▪To reduce corrosion
Abrasives used in dentifrices(toothpaste)
▪Phosphates ▪Carbonates
▪ Sodium bicarbonate ▪ Calcium carbonate
▪Silicas
Micromechanical bonding
bonding using surface irregularities smaller than can be seen with the naked eye or felt with a explorer. Interlocking of surfaces. ACID ETCHING is this!
Macromechanical bonding
the locking of two surfaces together using surface “roughness” and can be seen and/or felt.
Chemical adhesion in dentistry
▪Polycarboxylate cements
▪Glass ionomer cements
Adhesive failure
material breaks free from tooth, literally the adhesive material failed