armamentarium required for finishing and polishing of acrylic
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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
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