finishing and polishing materials in prosthodontics 18022017.pptx.pdf

finishing and polishing agents used in Dentistry

1. GOOD MORNING

2. FINISHING AND POLISHING MATERIALS
IN PROSTHODONTICS

3. Stepwise approach :

Introducing finer scratches to the surface of the substrate to
methodically remove deeper scratches
Finishing and polishing processes

4. Benefits of finishing and polishing :


•Finishing desired anatomy and esthetics, occlusion

•Polished surface Reduction in surface area Less retention of food
Reduced roughness debris, pathogenic bacteria


•Enhanced oral function

•Minimize wear of opposing and adjacent teeth

•Reduce stress concentration points improved strength

•Reduced tarnish and corrosion of metals

5. Carbide burs

Diamond burs

Abrasive particle
size
Bulk reduction8-12 fluted Coarse >100 micron
Contouring 12-16 fluted Medium
grit
30-100 micron
Finishing

118-30 fluted

Fine
and
Superfine

8-20 micron
Polishing <20 micron

6. Abrasive -outermost particles or surface material of an abrading
instrument
Substrate -The material being finished


ABRASION
Two body abrasion
Three body abrasion



FINISHING

Involves abrasive wear through the use of hard particles.

7. Abrasive action - principles

Harder material comes into frictional contact with the
substrate


Contact generates tensile and shear stresses


Break atomic bonds


Substrate particles are removed

8. Types of abrasion :


Two body abrasion

Abrasive bonded to instrument
Eg :- diamond bur abrading a tooth




Abrasive
Substrate

9. Substrate
Abrasive
Substrate
Types of abrasion :



Three body abrasion

Non bonded abrasives – abrasive particles are free

10. Erosion

wear caused by hard particles impacting a
substrate surface, carried by a stream of liquid or
air
eg :- sand blasting

11. Factors affecting rate of abrasion :
•Hardness
•Particle size of abrasive
•Particle shape
•Speed
•Pressure
•Lubricants

12. POLISHING

13. POLISHING


✔Purpose - to provide a lustre to the restoration/prosthesis

✔Use of progressively finer polishing media

✔Multidirectional

✔The surface must be cleaned between steps

✔The final stage produces scratches so fine that they are not
visible unless greatly magnified.

14. Polishing instruments
rubber abrasive points,
fine-particle discs and strips,
fine-particle polishing pastes.



Applicator - A nonabrasive material
Felt, muslin wheels ,leather, prophylaxis rubber cups,
and synthetic foam - for buffing.
Porous texture allows fine abrasive particles to be
retained during the buffing procedure.

15. Nonabrasive polishing


Composite glazing

Ceramic glazing

Electrolytic polishing

16. Truing :
Abrasive instrument is run against a harder abrasive block until
the abrasive instrument rotates in the hand piece without
eccentricity or run out when placed on a substrate



Dressing :
1)Reduces instrument to correct working size, shape
2)Removes clogged debris (abrasive blinding) - Restores
grinding efficiency

17. Classification of abrasives
Based on surface removal

1. Cutting Instruments : Tungsten carbide

2. Bonded abrasive :
• Diamonds • Silicon carbide • White stone • Tripoli • Rouge

3. Impregnated abrasives
• Aluminium oxide • Emery • Quartz • Silicon carbide
• Garnet • Zirconium silicate • Cuttle

4. Loose abrasives
• Aluminium oxide • Ultra fine diamond particles • Tin oxide
• Pumice

18. Natural abrasives

1. Arkansas Stone
2. Chalk
3. Corundum
4. Diamond
5. Emery
6. Garnet
7. Pumice
8. Quartz
9. Sand
10. Tripoli
11. Zirconium silicate
12. Cuttle
13. Kieselguhr

Synthetic Abrasives


1. Silicon carbide
2. Aluminium oxide
3. Synthetic diamond
4. Rouge
5. Tin oxide

19. ARKANSAS STONE



Semi translucent , light gray, siliceous sedimentary rock.

• Contains microcrystalline quartz.

• Attached to metal shanks and trued to various shapes

• Fine grinding of tooth enamel and metal alloys

20. CHALK









• Mineral forms of calcite.

• White abrasive composed of calcium carbonate.

• Used as a mild abrasive paste to polish tooth enamel, gold
foil, amalgam and plastic materials.

21. CORUNDUM

• Mineral form of aluminum oxide

• Physical properties are inferior to those of alpha aluminum
oxide.

• Grinding metal alloys

• A bonded abrasive in several shapes

• Used in instrument – White stone

22. NATURAL DIAMOND

• Transparent colorless mineral composed of carbon

• Superabrasive

• Supplied in several forms

Bonded abrasive rotary instruments

Flexible metal backed abrasive strips

Diamond polishing pastes.

• Used on ceramic and resin based composite materials

23. Diamond burs color coding and grit size

24. EMERY



• Natural form of an oxide of aluminium

• Grayish- black corundum

• Coated abrasive disks

• Greater the content of alumina - finer the grade of emery.

• Finishing metal alloys or acrylic resin materials.

25. GARNET

• Dark red, very hard .

• Comprise - silicates of Al, Co, Mg, Fe, Mn

• Garnet is coated on paper or cloth with glue.

• Fractured during grinding sharp, chisel-shaped plates

• Grinding metal alloys or acrylic resin materials.

26. PUMICE

•Highly siliceous material of volcanic origin

• Powder-crushing pumice stone

• Abrasive action is not very high

• Polishing tooth enamel, gold foil, dental amalgam and
acrylic resins

27. QUARTZ




• Very hard, colourless, and transparent.

• Crystalline particles are pulverized to form sharp, angular
particles - coated abrasive discs.

• Grinding tooth enamel and finishing metal alloys.

28. SAND



• 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

29. TRIPOLI





• Derived from light weight, friable siliceous sedimentary
rock.

• Rock is ground and made into bars with soft binders

• Colour- white/grey/pink/red/yellow

• Grey and red types

• Polishing for metal alloys and some acrylic resins.

30. ZIRCON/ZIRCONIUM SILICATE

• Off -white mineral.

• Ground to various particle sizes - coated abrasive disks and
strips.

• Component of dental prophylaxis pastes

31. CUTTLE

• Referred to as cuttle fish, cuttle bone, or cuttle.

• White calcareous powder

• Available as a coated abrasive

• Polishing of metal margins and amalgam restorations

32. KEISELGUHR

• Siliceous remains of minute aquatic plants - diatoms.

• Coarser form - diatomaceous earth

• Excellent mild abrasive

• Risk for respiratory silicosis caused by chronic exposure

33. SYNTHETIC SILICON CARBIDE

• Extremely hard abrasive and 1st synthetic abrasive

• Highly effective cutting of metal alloys, ceramics and acrylic
resin materials.

• Abrasive in coated disks and as vitreous - bonded and
rubber instruments.

34. ALUMINIUM OXIDE

• White powder

• used as bonded abrasives, coated abrasives and air
propelled abrasives.

• Finishing metal alloys, resin based composites and ceramic
materials.

• Pink and ruby variations- adding chromium compounds

35. ROUGE

• Consists of iron oxide, which is the fine red abrasive
component.

• Blended in to various soft binders in to a cake form.

• Used to polish high noble metal alloys

36. TIN OXIDE

• Extremely fine abrasive.

• Less abrasive than quartz.

• Polishing teeth and metallic restorations in the mouth.

• Produces excellent polish of enamel.

• Mixed with water or glycerin - abrasive paste

37. SYNTHETIC DIAMOND

• Controllable, consistent size and shape.

• Resin bonded diamonds have sharp edges

• Larger synthetic diamond particles – greenish

• Blocks with embedded diamond particles – truing other
bonded abrasives

• Used primarily on tooth structure, ceramics and resin
based composites

38. •

Finishing and polishing of Acrylic resin denture bases and
veneers

•Gypsum material left on the denture base following
processing and deflasking may be removed with a "shell
blaster.

• Small blemishes and bumps on the resin surface may be
scraped off or removed with an acrylic finishing bur.

• Denture base material is comparatively soft and can be
finished easily with a rag wheel and fine pumice followed by
tripoli or tin oxide.

•Care must be taken not to alter the contour of the denture
during finishing. Acrylic denture teeth are particularly easily
abraded by pumice.

39. Porcelain

Glazing in a porcelain oven.

Minor adjustments of the surface of a porcelain restoration

Polished using a series of coarse to fine abrasive rubber wheels
(containing silicon carbide or aluminum oxide)

Followed by a fine-particle-size diamond paste applied on a
felt wheel.

40. REVIEW OF LITERATURE

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44. REFERENCES

1.PHILIP’S SCIENCE OF DENTAL MATERIALS 13
TH
EDITION


2. Dental Materials and Their Selection - 3rd Ed. (2002) by William J. O'Brien

3.Mörmann WH etal Wear characteristics of current aesthetic dental restorative
CAD/CAM materials: two-body wear, gloss retention, roughness and Martens
hardness. 2013 Apr;20:113-25. doi: 10.1016/j.jmbbm.2013.01.003. Epub 2013
Jan 23.

4. Srividya S, Chandrasekharan Nair, Jayakar Shetty Effect of Different Polishing
Agents on Surface Finish and Hardness of Denture Base Acrylic Resins: A
Comparative StudyDOI: 10.5005/jp-journals-10019-1002 April 2011

5.Santing HJ Occlusal wear of provisional implant-supported restorationsClin
Implant Dent Relat Res. 2015 Feb;17(1):179-85. doi: 10.1111/cid.12072. Epub
2013 Apr 17

45. “If you avoid all of life's abrasions, you will never be
polished enough to shine.”

― Richelle E. Goodric

46. THANKYOU