/
Finishing  and  Polishing Finishing  and  Polishing

Finishing and Polishing - PowerPoint Presentation

VanillaSky
VanillaSky . @VanillaSky
Follow
345 views
Uploaded On 2022-08-04

Finishing and Polishing - PPT Presentation

Introduction Benefits of finishing and polishing Basic armamentarium Principles Cutting Grinding Bulk reduction process Contouring Air dispersed Hazards during finishing process What is Abrasive amp ID: 935797

abrasive finishing amp polishing finishing abrasive polishing amp abrasives bonded fine particles diamond oxide metal burs coated instrument material

Share:

Link:

Embed:

Download Presentation from below link

Download Presentation The PPT/PDF document "Finishing and Polishing" is the property of its rightful owner. Permission is granted to download and print the materials on this web site for personal, non-commercial use only, and to display it on your personal computer provided you do not modify the materials and that you retain all copyright notices contained in the materials. By downloading content from our website, you accept the terms of this agreement.


Presentation Transcript

Slide1

Finishing

and Polishing

Slide2

Introduction

Benefits of finishing and polishing

Basic armamentarium

Principles -

Cutting, Grinding

,

Bulk reduction process, ContouringAir dispersed Hazards during finishing processWhat is Abrasive & Erosive wearAbrasive Instrument DesignsTypes of Abrasives - Natural abrasives & Manufactured abrasivesAbrasive motionFinishing of various restorations composite, amalgam, ceramic, GIC, and cast goldREFERENCESCONCLUSION

Slide3

Introduction

The finishing process usually removes material such that :

Surface blemishes & imperfections are removed

Material is shaped to an ideal form

Outermost surface of the material is developed to a desired state

Slide4

Benefits of Finishing and Polishing

Benefits :

(a) Health (b) Function (c) Aesthetics

Slide5

Cutting

Cutting refers to use of a bladed instrument or the use of any instrument in a bladelike fashion.

Course of action – predominantly unidirectionalCutting operation – may divide substrate into large separate pieces / produce deep notches or grooves

E.g. High speed tungsten carbide burs

steel burs

There are distinct differences in function of cutting, grinding, finishing and polishing

Slide6

Grinding

It is a process that removes small particle of a substrate through the action of bonded or coated abrasive instruments .

Course of action – predominantly unidirectional

Grinding instrument - contain many randomly arranged abrasive particle .

Each particle may contain several sharp points that run along the substrate surface and remove particles of materials .

Eg Diamond coated rotary instrument

disk & strips .

Slide7

Bulk reduction process

Instruments used

Diamond, carbide and steel burs Abrasive coated disks or separating disks

Abrasive coated disks –

popular bulk reduction of resin based composite restorations

Clinician should choose 8 to 12 fluted carbide burs or abrasives with particle size of 100 micrometers or more with

sufficient hardness.

Slide8

Contouring

Though it can be achieved during bulk reduction, in some cases it requires finer cutting instruments or abrasives to provide better control of contouring and surface details.

At the end of the process, desired anatomy and margins should be established.

Usually 12 to 16 fluted carbide burs or abrasives ranging in size from 30 to 100 micrometers provide the fine contouring action.

Slide9

FINISHING AND POLISHING

Provides blemish free & smooth surfaces

Requires step wise approach

18-30

8-20 um particle size

POLISHING

: provide enamel like luster Speed of achieving polishing depend on 2 factor a) hardness & size of abrasive b) method of abrasion Polishing & luster can be judged by :1 , 2 , 3 methodsWhat is Abrasive Blinding ?

Slide10

AIR DISPERSED HAZARDS OF FINISHING PROCESS

AEROSOL – HEALTH HAZARD

95% of generated aerosol particles - < 5µm in diameter – can readily reach pulmonary alveoli during normal respiration

75% of aerosol particles – potentially contaminated with infectious microorganisms

Aerosols can remain airborne for >24hours – therefore capable of cross-contamination

Slide11

If inhaled, swallowed or if it enters the eyes

Diseases of the lungs ,throat and eyes.

Silica based materials if inhaled

Silicosis or Grinders disease.

(Fibrotic pulmonary disease)

(major aerosol hazard)

Slide12

AEROSOL - CONTROL

3 ways :

Controlled at the source –

adequate infection control procedures

High – volume suction

Personal protection –

Safety glassesDisposable face masksAdequate ventilation system –To remove any residual particulates from air

Slide13

WEAR

Wear – is a material removal process that can occur whenever surfaces slide against each other.

2 types a) Abrasive wear b) erosive wear

Slide14

Abrasive wear is divided into:

-

Two Body Abrasion - Three Body AbrasionThe two processes are not mutually exclusive

Three body abrasion

when abrasive particles are free to translate and rotate between two surfaces.

Eg. Dental Prophylaxis Pastes.

.Two body abrasion occurs when the abrasive particles are firmly bonded to the surface of the abrasive instrument and no other abrasive particles are used.Eg. Diamond bur abrading a tooth.

H

ow

t

o

p

revent

i

t

?....

Slide15

Erosion

Erosive wear is caused by hard particles impacting a substrate surface, carried either by a stream of liquid or air.

Eg. Air-driven grit-blasting units - employ hard particle erosion to remove surface material

Slide16

- important factor in controlling the instrument action on the substrate.

Bur in high speed handpiece rotates in clockwise direction.

Smoother grinding action – when handpiece & bur are translated in a direction opposite to rotational direction of the bur.

Rougher surface – when handpiece & bur are translated in the same direction as rotational direction of the bur.

(Bur tends to “runaway” from the substrate)

The rotational direction of a rotary abrasive instrument

Slide17

ABRASIVE INSTRUMENT DESIGNS

These are :

Abrasive gritsBonded abrasives

Coated abrasive disks and strips

Non bonded abrasives

Slide18

Abrasive Grits

Derived from crushed materials passed through a series of mesh screens to obtain different particle size ranges.

Classification according to particle size ranges:

Coarse

Medium coarse

Medium fine

Super fine

Slide19

Bonded Abrasives

Consist of abrasive particles incorporated through a binder to form grinding tools such as points, wheels etc.

Particles are bonded by four methods:

Sintering

Vitreous bonding

Resinoid bonding

Rubber bonding

Slide20

Coated Abrasive Disks And Strips

Fabricated by securing abrasive particles to a flexible backing material with a suitable adhesive material.

Supplied as disks and finishing strips.

Slide21

Non Bonded Abrasives

Polishing pastes are considered

non bonded abrasives Primarily for final polishing

Need to be applied to the substrate with a non abrasive device like synthetic foam, rubber felt etc.

Abrasive particles are dispersed in a water soluble medium such as glycerin.

Most popular aluminium oxide and diamond

Slide22

Types of Abrasives

NATURAL ABRASIVES:

Arkansas stone

Chalk

Corundum

Diamond

Emery Garnet PumiceQuartz SandTripoli Zirconium silicateCuttle Kieselguhr MANUFACTURED ABRASIVES: Synthesized material that are usually preferred – more predictable physical properties Silicon carbide, Aluminium oxide

Synthetic diamondRouge Tin oxide

Slide23

ARKANSAS STONE

:

- Semi translucent, light gray, siliceous sedimentary rock, mined in Arkansas. - Contains micro crystalline quartz

- Dense, hard and uniformly textured.

- Can be made into various shapes.

- Use : to grind tooth enamel & metal alloys

CHALK: - Mineral form of calcite. - White abrasive - Composed of calcium carbonate. - Use : polish tooth enamel, gold foil, amalgam & plastic materials.

Slide24

CORUNDUM:

- Mineral form of aluminium oxide - Usually white

- Use : grinding metal alloys. - Most commonly used in instrument known as “white stone”

NATURAL DIAMOND:

-

Transparent colorless mineral - Composed of carbon - Hardest substance. - various forms : Bonded rotary instruments Diamond polishing pastes Flexible metal-backed abrasive strips - Use : on ceramic & resin-based composite materials

D

ifference

b

etween

n

atural

&

s

ynthetic

d

iamond

Slide25

SYNTHETIC DIAMOND ABRASIVES:

- Advantage: controllable

consistent size and shape

lower cost

- Resin bonded diamonds sharp edge the sharp edge breaks down; exposes new sharp edges, corners. - Metal bonded diamonds regular, more consistent in size. Use cutting points. - Large synthetic diamond particles greenish.

Slide26

EMERY:

- Grayish - black

- Fine grain form - Used form of coated abrasive disks. - Use : Finishing metal alloys or plastic materials

GARNET:

-

Includes number of different minerals that possess similar physical properties & crystalline forms - Usually dark red. - Extremely hard - Use : Grinding metal alloys and plastic materials

Slide27

PUMICE: - Light - Gray

- Highly siliceous material - 2 form:-Grit

-Rubber bonded abrasives

- Use :- polishing tooth enamel

- gold foil

- dental amalgam QUARTZ:Most commonly used is very hard colourless and transparent.Use : - finish metal alloys, - grind dental enamel.

Slide28

SAND:

- Mixture of small mineral particles - Predominantly composed of silica.

- Rounded to angular shape - Use : Grinding metal alloys & plastic materials

TRIPOLI:

- Derived from a lightweight siliceous sedimentary rock.

- grey and red coloured are the most commonly used

- Use: Polishing metal alloys and some acrylic resins.

Slide29

ZIRCONIUM SILICATE: - Supplied as an off white material

- Use: - To make coated abrasive disks & strips - As component of dental prophylaxis pastes.

KIESELGUHR:

- Composed of siliceous remains of minute aquatic plants known as diatoms.

- Use : Mild abrasive - Significant risk of respiratory silicosis

Slide30

SILICON CARBIDE:

- First of synthetic abrasives - Two types; green and blue

- They are extremely hard and brittle ROUGE:

- Iron oxide is a fine, red abrasive component of rouge.

- Use : Polish high noble metal alloys

TIN OXIDE:

- Extremely fine abrasive - Use : polishing agent for polishing teeth and metallic restorations ALUMINIUM OXIDE: - Second synthetic abrasive developed - Use : To make bonded abrasives, coated abrasives and air propelled grit abrasives. - Sintered aluminium dioxide is used to make white stone (popular for adjusting dental enamel and finishing metal alloys & ceramic materials)

Slide31

ABRASIVE MOTION

Classified asRotary Burs

Planar DisksReciprocal Reciprocating hand pieces

Note :Reciprocating hand pieces provide benefit of accessing interproximal and subgingival areas to remove overhangs, to finish subgingival margins without creating ditches and to create embrasures

Slide32

Finishing and Polishing of Different Restorations

Slide33

Armamentarium :

Fibro optic lighting and magnification (for visibility)Fine grit conventional diamonds (for gross reduction)Round tungsten carbide burs (finishing)

Flame shaped fluted tungsten burs (finishing)Impregnated rubber wheels or points (finishing)Slurry of fine aluminium oxide (polishing)

Composites

Composite finishing kit

Composite finishing paste

impregnated rubber wheels or points

Slide34

Initial finishing by a sharp knife

Final Finishing

In DCNA 1998 study was done on finishing procedure ………..

Slide35

Amalgam

In the past a delay of 24 hrs had been suggested before finishing and polishing the newly inserted amalgam Armamentarium :

Rhein trimmers (Discrepancies in gingival area )Bard parker knife number-12 (Bulky overhangs )Narrow water resistant strip (19)(Cervical areas )

extra fine water proof disk (Buccal and lingual proximal margins )

small carrot shaped stone (20) (Occlusal margins )

plug finishing burs (21) (further adjustment )

Rubber cup (finish accessible proximal surfaces as well as occlusal contours)Abrasive impregnated silicon rubber points and cupstin oxide slurry (complete the finishing and polishing procedures)soft cut brush (complete the finishing and polishing procedures)

Slide36

Finishing and polishing cannot be started until a future visit when the amalgam will have set hard.

Any sizeable reduction may be undertaken with a carborundum point.

Slide37

Adequate cooling is important in vivo when finishing and polishing ceramic restoration

Using an air water spray and maintaining intermittent contact between restoration and rotary instruments are critical during operation

Continuous contact between restoration and rotary instruments should be avoided

Heat less stone like silicon carbide provide heat reduction and can be used as an alternative

Ceramics

Slide38

Techniques

Contour with flexible diamond disc, diamond burs, heatless or polymer stones or greenstones

Finish with white stones or abrasives impregnated rubber disc, cups and points

Apply over glaze or natural glaze on ceramic if necessary

Slide39

Glass Ionomer Cement

Slide40

Problem of water loss continues for a longer period for both fast and slow set types and precautions should be taken to prevent dehydration.

Diagramatic representation of water balance in glass ionomer. Type ii and I restorative aesthetic restorations remain succeptible to water uptake for at least one day after placement.All the types are fast settig gic and so are resisting to water uptake within 5 to 6 mins from the beginning of mix.

Slide41

The best surface attainable is that produced when the cement is allowed to set against the matrix.

Where access can be gained, carving the cement external to the cavity margins with sharp knives or scalers after initial set is the best process of finishing.

Whenever possible, margins should be smoothed with hand instruments.

Finishing with rotary instruments and final polishing can be undertaken at a subsequent visit.

Glass ionomer should never be finished under dry conditions; a petroleum lubricant may be used to prevent desiccation.

Slide42

Finishing Of GIC Restoration

Finishing with a bur Finished GIC Restoration

Slide43

CAST GOLD RESTORATION

Use a 1/2 inch medium garnet disc in a straight handpiece to reduce gold and tooth to the same plane on all surfaces (use contra-angle with grit in to reduce mesial-lingual, where necessary, for both maxillary and mandibular restorations). Air should be blown continuously on the tooth to prevent overheating during all disking, stripping and polishing procedures.

Slide44

Finished cast gold restoration

Use fine and extra-fine narrow, extra-long cuttle strips to reduce the size of scratches.

Complete disking with fine cuttle discs until all scratches have been removed.

Slide45

Polish with flour of pumice. Do not use coarse pumice as it will destroy the finish achieved with the fine cuttle disc.

Use dry tin oxide powder over casting for final polish. Blow off excess tin oxide while utilizing a ribbed cup (webbed cup will throw powder away from tooth) at low speed to avoid heating the tooth.

Slide46

References

Phillips Science of Dental Materials.

Atlas of operative DentistryAtlas of G. J. Mount

Allen D. Wilson

Charbenau

David Korson

Ratnadeep PatilJ.R. Grundy

Slide47

CONCLUSION

Fluted carbide

finishing bur appear to be the optimal rotary

contouring

device

FINISHING DIAMOND preferred for GROSS FINISHING COATED DISK & STRIPS provides access for interproximal & incisal area RUBBERIZED BONDED provide great range of FINISHING ALUMINIUM OXIDE & DIAMOND PASTE are highly effective against POLISHING

Slide48

THANK YOU

& HAVE A NICE DAY………….