Dr. Mamunur Rashid

Department of Prosthodontics

Sapporo Dental College & Hospital

ID:07041

1. To obtain the desired anatomy and proper occlusion.

2. Reduction of roughness and scratches.

3. To obtain smooth surface which resist bacterial adhesion & excessive plaque accumulation by this way it maintain oral health.

4. Esthetics: finishing and polishing gives luster to visible surface of restoration and increase optical property of restoration.

Contouring: Process of producing desired anatomic form by cutting away excess material.

Cutting: Process of removing the material from substrate by the use of a bladed bur or an abrasive embedded in a binding matrix on a bur or disc.

Finishing: process of removing surface defect or scratches by the use of cutting or grinding instrument or both.

Polishing: The most refined of the finishing process ,removes the finest surface particle.

Bulk reduction

• Removal of excess material

• Instruments – sand stone, carbide and steel

burs, abrasive coated disks, or separating

disks.

• 8 - 12 fluted carbide burs or abrasives with

particle size of 100µm or larger

• Achieved during bulk reduction

• Finer instruments may be used

• Desired anatomy and margins must be

achieved.

• 12 - 16 fluted carbide burs or 30 - 100 µm sized

abrasive particles used

• Introducing finer scratches to surface of

substrate

• Provides a blemish free smooth surface.

• 18 - 30 flute carbide burs , fine and super fine

diamond burs, or abrasives between 8 and 20

µm in size.

• Provides enamel like luster.

• Smaller particles provide smoother and shinier

surfaces

• Abrasives of 20 µm provide luster

• Importance of polishing:

• Less bacterial colonization

• Comfortable for the patient

Cutting instrument: Tungsten Carbide Burs. Lathe motors. Micro-motor Trimmer(Acrylic Trimmer) Bonded Abrasives:

i. Silicon Carbide ii. White stoneiii. Tripoliiv. Rougev. Diamond

Impregnated Abrasives.i. Aluminum oxide.ii. Emery.iii. Quartz.iv. Silicon carbide.v. Garnetvi. Zirconium Silicate.

Loose Abrasives:i. Aluminum oxide .ii. Tin oxide.iii. PumiceAccording to source: Natural abrasivesi. Chalk.ii. Diamond.iii. Emery.iv. Garnet.v. Pumicevi. Quartz.vii. Sand .viii. Tripoli.

• Diamond - 7500 KHN

• Silicon carbide - 2500 KHN

• Aluminum oxide - 2100 KHN

• Emery - 2000 KHN

• Corundum - 2000 KHN

• Tungsten carbide - 1900 KHN

• Garnet - 1350 KHN

• Quartz - 800 KHN

• Sand - 560 KHN

• Pumice - 560 KHN

• Chalk - 135 KHN

Use:when fix with a Micromotor trimmer,it is use for:-

a. To remove the excess material from Denture to create a smooth surface.

b. Give desired anatomic form by cutting away excess material.

c. Remove surface defect and scratches.

--------------------- Shank ----------------<--------Neck ------<- Head>

The cutting property of a bur varies with the positioning and the degree of angling of the blades. More obtuse angles will produce a negative rake angle, which increases the strength and longevity of the bur. More acute angles will produce a positive rake angle, which offers a sharper blade for quicker cutting but which dulls sooner. Additional cuts across the blades, called“crosscuts,” can be added to increase cutting efficiency

Foot Control

Cradle

Control

Hand piece

Uses: Used to finish and polish acrylic denture by adding different bur and Sand paper

How to operate:Connect the motor cord and foot pedal cord to control unit.After confirm the permission power the control unit ,plug the power cord into an electric outlet.Set the speed control knob to the lowest position.Turn the power of the control unit.To increse the micromotor speed turn the speed control knob clockwise.It can either control by pedal or control switch.

It ensures vibration free rotation even at the maximum speed of 35000 RPM( Rotation per minute)

High torque at all speed.

Can be operated by both hand and foot control, Reverse and forward rotation by hand switch, on/off foot switch.

Mounting & Removing a bur:After turn the set ring of the hand piece clockwise to open the

collet chuck, extract a old bur.

After insert perfectly a new bur until reach in the back of the collet chuck, turn the set ring counter-clockwise to lock the collet chuck.

Uses:

Apply polishing compound on a buff or rag wheel and polish the dentures to a high gloss.By adding different polishing buff it is able to produce a luster and shiny surface.

Extremely hard abrasive and 1st synthetic

abrasive.

Highly effective cutting of acrylic resin materials.

Abrasive in coated disks and as vitreous - bonded

and rubber instruments.

•Mineral forms of calcite.

•White abrasive composed of

calcium carbonate.

•Used as a mild abrasive paste

to to polish Acrylic resin.

• Natural form of an oxide of

aluminum

• Grayish- black corundum

Coated abrasive disks

• Greater the content of alumina

- finer the grade of emery.

• Finishing of metal alloys or

acrylic resin materials.

• Highly siliceous material of volcanic

origin

• Powder-crushing pumice stone

• Pumice should be loaded on a lathe mounted rag wheel

• Pumice powder mix with water is coated over the rag wheel.

• The finished denture should be polished by intermittently pressing against the rotating rag wheel

• Predominantly composed of silica.

• Particles represent a mixture of color.

• Rounded to angular shape.

• Applied under air pressure to remove

refractory investment materials

• Coated on to paper disks

Textbook of Denture Prosthodontics . http://www.airforcemedicine.af.mil/shared/media/docu

ment/AFD-130329-077.pdf http://handlermfg.com/products/index.php?main_page=i

ndex&cPath=34_49 http://www.usdentaldepot.com/Dental-

supplies/MARATHON-3-CHAMPION-MICROMOTOR-40000RPM-%28-%29P101536

h t t p : / / d e n t a l h a n d p i e c e s r e p a i r s . c o m / Historyofdentalhandpieces.aspx. Accessed December

1,2008. 3 Poole RL, Lea SC, Dyson JE, Shortall AC, Walmsley

AD.Vibration characteristics of dental high-speed turbines andspeed-increasing handpieces. J Dent. 2008 Jul;36(7):488