Abrasion, finishing, and polishing ch 13

What is finishing?

Process of shaping excess restorative material to create proper bite and contour, smooth out surface imperfections, and leave a polished finish.

What is polishing?

Procedure that creates a shiny, smooth surface by removing fine scratches, small imperfections, and surface stains.

Rate of abrasion is determined by..?

• Size of particles

• Irregularity of particles

• Hardness of the particles

• Number of particles contacting the surface

• Pressure and speed with which particles are applied

What is hardness?

The ability of a material to resist wear or scratching

Rate of abrasion depends on..

• Materials being abraded

• Pressure applied

• Speed of the rotating device

• Larger, irregular particles cut more efficiently

• Diamonds are the most abrasive material in dentistry

Speed and pressure effects

Higher pressure= deeper scratches, less control

Faster speed= more heat, which can harm tooth structure and comfort

Types of abrasives

• Loose Abrasives: Powders, pastes (classified by grit size)

• Coated Abrasives: Discs, finishing strips

• Bonded Abrasives: Rotary tools with embedded particles

Materials used in abrasion

• Diamond

• Carbide finishing burs

• Silicon carbide

• Sand-coated disks

• Silicone dioxide

• Pumice

• Aluminum oxide paste

• Aluminum oxide-Burlew wheels

• Rouge – iron oxide, block form, rag wheel

• Tin oxide – powder mixed w/ water or glycerin

• Calcium carbonate – Prophy paste and dentifrice

Amalgam polishing process

• Polished only after 24 hours from when it was placed.

• Regular polishing can help reduce creep and corrosion.

Composite 3 step process

1. Marginal and occlusal excesses 1st removed

2. Disks, cusps and strips sequentially

3. Polishing paste with cups or pads

Composite and Gold Alloy Polishing

• Remove any scratches after fitting

• Use Burlew wheels for gold alloys

• Diamond polishing paste or rubber points for finishing

Coronal Polishing

• Use rubber polishing points and wheels

• With diamond polishing paste

Air Polishing (Like a power washer)

Effective method using powder, air, and water under pressure to clean enamel, pits and fissures

What are polishing devices used for dentures and crowns?

Cloth rag wheels and polishing brushes attached to slow-piece handpieces smooth and shine dentures and crowns.