SEMINAR ON

RETRIEVEL OF DENTURE, CORRECTION OF OCCLUSAL

DISCREPANCIES,FINISHING AND POLISHING PROCEDURES.

CONTENTS

Introduction

Review of Literature

Definitions

Deflasking procedure

Problems cause during Deflasking

Causes for dimensional changes in complete denture during processing

Lab remounting procedure

Correction of Occlusal discrepancies by selective grinding

Advantages of selecting grinding

Removal of denture from cast

Finishing of complete denture

Polishing of complete denture

Summary & conclusion

References.

INTRODUCTION

Successful fabrication of complete dentures requires a combination of sound

clinical as well as laboratory procedures. Clinical procedures however accurate are not of

much use if the laboratory procedures are not properly carried out from the pouring of

casts to retrieval of denture & finishing & Polishing of dentures all go a long way in the

success of the prosthesis.

Carelessness in the final stages of denture fabrication such as during retrieval of

dentures from the flasks, failure to correct the Occlusal discrepancies induced as a result

of processing & inadequate finishing & polishing will result in dentures which are far

below the result that could have been achieved if a little more time & efforts would have

been invested in the final stages. This seminar deals with these steps in the making of a

denture which are generally given least importance but if properly done, greatly enhance

the comfort function & esthetics of the final prosthesis.

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Review of the Literature:

1. Nikazad s Javing 1973 : Described a method the top half of molds for processing

dentures were made in the top half of the flask. This technique speeds up the

removal of processed dentures from their molds and reduces the possibility of

fracturing either the denture base or the teeth.

2. Majid Bissasu 1998 : Described a easy procedure to facilitate the removal of the

palatal and lingual portions of flasking stone. So it reduces the hazards of

denture base fracture or deformation during Deflasking of the processed

denture. Advantage of this procedure is it reduces the flasking and Deflasking

time.

3. Than-E-Holf 1977 : Conducted a study that incited that numerous benefits from

remounting dentures to correct occlusion and recon touring the tissue side of

the bases at the time of insertion. He showed that post insertion complaints

were decreased by remounting procedures.

4. Garrent D Barrett 1985 : Described a reprocible split cast technique for accurate

demounting and remounting of a Pre – or post processing complete denture

master cast without stress or fracture.

5. Sigmund 1953 : Conducted a study on investing changes during flasking may lead

to malocclusion in complete duve. There is sufficient evidence to indicate

that there is some shifting of the teeth during the investing procedure &

described methods to reduce this shifting.

6. Robert C. Wesley 1973 : Conducted study in 50 patient regarding posterior tooth

contact and pin opening during processing changes in complete denture it was

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found that there was a definite shift of the tooth contacts to the more posterior

teeth after processing but that the amount of pin opening did not seems to be

related to the number of location of the tooth contacts.

7. William A walker, Donal C Kramer and Rager Marcev 1978 : Described a

detailed step – by – step procedure for finishing and polishing denture based

produce highly polished surfaces free from all imperfection.

8. Mutahhar Ulusay, Nuron Ulusoy, Keveser Aydin 1986 : Evaluated polishing

techniques of surface roughness of acrylic resin. 9 methods of grinding &

polishing heat cute resins were evaluated. They found that the best surface

finish was obtained when abrasive stones coarse medium fine abrasive discs

rotating felt come and rotating soft brush C chalk powder were used

progressively.

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Definitions:

Definition for Deflasking:

Definition of Remounting:

Any method used to relate restorations to an articulator for analysis and for to assist in

development of a plane for occlusal equilibration or reshaping.

Definition of Selective Grinding:

The intentional alteration of the occlusal surfaces of teeth to change their form .

Definition of finishing:

It is process to put a final coat or surface on, the retirement of form prior to polishing.

Definition of Polishing:

The act of process of making a denture or casting smooth and glossy.

Deflasking: When Deflasking complete dentures it is best to use a Deflasker which

allows retrieval from the flask without damage to the dentures or flask. Deflasking with a

hammer can damage. The flask and results in unnecessary breakage of the dentures.

Procedures for Deflasking of complete denture :

1. Remove the Lid from the flask containing the bench cooled denture.

2. Place the flask bottom side up in the Deflasker and tighten the thumb screw until

it contacts the bottom plate.

3. Place the pry bars through the slots in the side of the Deflasker and engage. The

slots in the flask between both halves of the flask.

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4. Press down on the engaged pry bars first and then pry up these movements readily

separate the flask from the stone enclosed denture.

5. Place a Knife-blade in contact with the junction between the stone cap and the rest

of the stone enclosing the denture. Tap the back of the knife blade with a plastic

mallet to separate the stone cap and to expose the cusp tips and incisal edges of

the denture teeth.

6. Use care in separating the stone cap from dentures with acrylic teeth.

7. With a saw and a spiral blade, cut through the stone that encloses. The denture

opposite the central incisor teeth take care to avoiding sawing into teeth or

denture blast.

8. Place more saw cuts at the distobuccal corners of the flasked denture. So that the

stone enclosing the denture has three cuts.

9. Place a knife in the anterior saw cut and pry gently to separate the stone from the

buccal and anterior flanges of the denture.

10. Place a knife in the posterior cut, and pry laterally to separate any posterior

section of stone may have adhered to the buccal flange of the denture.

11. Remove stone from the palate or tongue area of the mandibular dentures by first

relieving the stone adjacent to lingual surfaces of the denture teeth with a knife

take care to avoid cutting teeth or denture base.

12. After reliving the stone adjacent to the lingual surfaces of the denture teeth, gently

pry the stone in the lingual area of the denture or the palate of the maxillary

denture, and lift it away from the denture.

13. Make more cuts lingual to the heel area of the mandibular dentures if necessary.

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14. Remove the denture from the investing stone except where it encloses the cast.

15. Protect the teeth with the hand and with a plastic mallet carefully tap away the

stone enclosing the cast. Exercise care to avoid damaging the teeth by striking

them with the mallet.

16. Use a tooth brush to clean out the index groove on the base of the cast. This

cleansing makes if possible to position the cast accurately on the mounting stone

for correction.

17. After retrieval from the stone the dentures are ready for remounting on the

articulator.

Problems that occur during Deflasking are

1. Breaking of the denture

2. Breaking of the cast

3. Breaking of the both cast and denture.

4. Denture base or denture teeth broken during Deflasking as result of using a

hammer to tap stone from the flask.

Attention to the details of flasking to eliminate under cuts, proper use of tinfoil

substitute, and careful Deflasking procedures minimize breakage of dentures and

facilitate raid retrieval.

Causes for dimensional change in denture during processing.

1. Polymerization shrinkage.

2. Processing stresses.

3. Incorrect registration of centric occlusion.

4. Irregularities in setting teeth.

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5. Tooth movement when flasking and packing.

6. Incomplete flask closure.

7. Wear in moving parts of articulators.

Polymerization shrinkage: When methyl methacrylate monomer is polymerized to form

poly (Methyl Metharcylate), the density of the mass changes from 0.94 to 1.19 g/cm.

This change in density results in volumetric shrinkage of 21%. When a conventional heat

activated resin is mixed at the suggested powder Liquid ratio, about one third of resultant

mass is liquid. Consequently the volumetric shrinkage exhibited by the polymerized mass

should be approximately 7%. In addition to volumetric shrinkage, one also must consider

the effect of linear shrinkage. Linear shrinkage exerts significant effects on denture base

adaptation and cuspal interdigitation. By convention, linear shrinkage values are

determined by measuring the distance between two predetermined reference points, in the

second molar region of a completed tooth arrangement. After polymerization of the

denture base resin and removal of prosthesis from the master cast the distance between

prepolymerization and post polymerization measurements is recorded as linear shrinkage

the greater the linear shrinkage the greater the discrepancy observed in the initial fit of a

denture. Based on a projected volumetric shrinkage of 7%, an acrylic resin denture base

should exhibit a linear shrinkage of approximately 2%. In reality linear shrinkage

generally is observed to be less than 1%.

Examination of the polymerization process indicates that thermal shrinkage of

resin is primarily responsible for the linear shrinkage phenomenon in heat activated

systems. During initial stages of cooling process the resin remain relatively soft.

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Therefore the pressure maintained on the flask assembly causes the resin to contract at

approximately the same rate as the surrounding dental stone.

As cooling proceeds, the soft resin approaches its glass transition temperature

(Tg). The Tg lies with in a thermal range in which the polymerized resin passes from a

soft, rubbery state to a rigid, glassy state. Hence, cooling the denture base resin beyond

the Tg. Yields, a rigid mass. In turn this rigid mass contracts at a rate different from the

surrounding dental stone. The shrinkage occurring below Tg is thermal in nature and

varies according to the composition the resin.

To illustrate the effect of thermal shrinkage, consider the following example. The

Tg for poly (Methylmethacrylate) is approximately 1050C room temperature is 200C. The

generally accepted value for linear co-efficient of thermal expansion for poly (methyl

methacrylate) is 81 x 10-6 per degrees centigrade therefore as the denture base resin is

cooled from the Tg. To room temperature it undergoes linear shrinkage that may be

expressed as.

L T = (81 x 10-6/0C) (1050C - 200C) (100%) = 0.69%

2. Processing Stresses : When ever a natural dimensional change is inhibited, the affected

material contains stresses. If stresses are relaxed, a resultant distortion or warpage of the

material may occur. This principal has important reminification in the fabrication of

denture bases, because stresses invariably are induced during processing.

Stress also are produced as the result of thermal shrinkage as a polymerized resin

is cooled below its Tg. The resin becomes relatively rigid. Further cooling yields thermal

shrinkage. A denture base resin generally is encased in a rigid investing medium, such as

dental stone, during this process. Because denture base resins and dental stones contract

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at markedly different rates, a contraction differential is established. Hence a disparity in

contraction rates also yields stresses with in the resin. Additional factors that may

contribute to processing stresses with in resin. Additional factors that may contribute to

processing stresses include improper mixing and handling of the resin and poorly

controlled heating and cooling of the flask assembly.

The release of stresses yields dimensional changes that a cumulative in nature.

Fortunately, these dimensional changes are quite small total dimensional changes

occurring as a result of processing and service are in the range of 0.1 to 0.2 mm (as

measured from Second molar to Second molar). Therefore it is doubtful such changes

would be clinically significant and they detectable by patient.

3. Incorrect Registration of Centric occlusion: This is probably the most common cause

of error in the occlusion of finished dentures when registering the position of centric

occlusion considerable care is taken to obtain a correct vertical dimension and

physiological fully retruded position of the mandible, but often the record rims when

brought together exert uneven pressure on their respective supporting alveolar ridges.

This is due to premature contacts of the record rims on side of the mouth in Second molar

region. This causes uneven compression of mucosa supporting the record blocks and

often displaces them from ridges.

Another fault causing errors in the occlusion of the finished dentures results from

slight movement of record blocks on the ridges during centric registration due to their

imperfect fit and inadequate retention.

Another error of occlusion may result from the manner in which the models and

record blocks are set in the articulator. The models may not be placed accurately in the

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blocks or the articulator may not handled with due care when the models are being

attached with plaster.

4. Irregularities in setting the teeth :

The technician when setting up teeth is unlikely to produce a perfectly even contact in

centric and lateral occlusions. Some teeth will be in good occlusion whilst others will be

slightly out of occlusion, thus producing areas of heavy pressure. In waxing up following

the setting of teeth it is possible for them to more slightly due to the contraction of the

wax on cooling, causing irregularities in the articulation and occlusion of complete

dentures.

5. Tooth movement when flasking and packing :

Movement of the teeth may occur at the time of boiling out the wax trial base after the

dentures have been flasked and it such teeth are not correctly repositioned they will cause

minor Occlusal irregularities. Also, when packing, teeth may be driven into the

enveloping plaster, particularly when packing follows soon after investing and the plaster

is in the ‘green state’. The possibility of such an error occurring is increased when the

methyl methacrylate is used in a slightly advanced stage of dough, and when the posterior

teeth have been ground to fit close to the ridge. Rapid closure of the flask in the piets

will add to the hazard.

6. Incomplete flask closure :

This causes not only, an increase of vertical dimension but also results in an upset of

balanced occlusion.

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7. Articulator wear :

All articulators are subject to wear and the older and more worn the articulator the greater

will be the errors in occlusion and articulation. Every piece of mechanical apparatus

exhibits some play in its moving parts and when this becomes easily detectable the

bearing should be replaced.

Split-cast procedure for remounting the complete denture master cast

Accurate remounting of the detached complete denture master cast to its mounted

articulated base is essential to maintain the original articulated interarch and occlusal

relationship. Inaccurate remounting will result in occlusal discrepancies. In this

technique describes a reproducible split-cast technique for accurate demounting and

remounting of a pre-or past processing complete denture master cast without unwarranted

stress or fracture.

Technique:

1. Require the master cast from the boxed final impression boxing will preserve the

appropriate morphologic border contours and master cast base thickness.

2. Finish the base of master cast with a fine model trimmer wheel.

3. Cut two posterior and one anterior index grooves into the master cast base. After

refinement apply a thin coating of petroleum Jelly to each index groove with a

cotton pellet. It is not necessary to lubricate the entire base.

4. Using Jaw relation records, mount the moist master cast in the articulator using

fast setting plaster. When the plaster sets, smooth and refine the mounted master

cast an articulated base so that a crisp demarcation interface exists between the

cast and plaster base.

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5. Remove the master cast and its articulated base from the articulator. Fill a

standard mixing bow 1 with near boiling water (minimum temperature of 1800F)

to a level approximately 1 inch greater than the height of the articulated base.

6. Place the articulated base with the mounted master cast into the hot water and

adjust the water level to a point 2 to 4 mm above the interface. Leave the

mounted master cast in water for 10 seconds or until the cast and base separate.

The sudden temperature change and expansion of the base plaster causes

separation. Do not completely immerse the mounted master cast.

7. When remounting the cast wet the entire articulated plaster base and only the base

portion of the master cast. Fit the plaster base and base portion of master cast

together, and allow them to dry. A perfect readaptation of the master cast and

articulated base will result.

8. Cut parallel horizontal grooves on the lateral surface to secure the master cast to

the articulated base. After the surfaces are moistened, apply a thin mix of plaster

into grooves and extended over both the cast and base. Smooth and position the

remounted cast and its base on the articulator.

Procedure :

1. After remounting the dentures in the articulator check the relationship of the

incisal guide pin to the incisal guide table. After the incisal guide pin does not

contact the incisal guide table because of changes during processing a processing

error of 1 mm though not insignificant, is correctable. However, an error of more

than 1 mm which often requires considerable reduction on the Occlusal surfaces

of the denture teeth to regain the vertical dimension of occlusion is undesirable.

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2. Check contacts between the heel of mandibular dentures and the tuberosity region

of maxillary dentures to make certain that the increase in vertical dimension is not

result of an overly thick denture base resin in these areas.

3. Place articulating paper between the teeth and gently tap the articulator together to

indicate defective occlusal contacts.

4. Adjust these contacts with a stone bur, if the teeth are porcelain or if the teeth are

resin, continue to adjust the occlusion in the centric relation position and in the

eccentric positions, according to the rules of selective grinding. Do not adjust the

cusps in centric relation position unless they are high not only in the centric

relation position, but also in the right-and left lateral and protrusive positions.

Generally, reduction results in grinding of the fossae rather than the cusp tips.

When adjusting the working position, adjust the buccal cusps of the upper teeth

and the lingual cusps of the mandibular teeth to eliminate defective contacts. On

the non working, or balancing side defective contacts are usually on centric

holding cusps and grinding requires a compromise we prefer to grind the inclines

of the maxillary lingual cusps rather than the buccal cusps of the mandibular

dentures.

5. Move the articulators into a working position and examine the relationship of the

working cusps, mark the defective contacts with articulating paper and examine

the resulting pattern. Eliminate defective contacts on porcelain teeth by adjusting

the buccal cusps of the maxillary lingual teeth and the lingual cusps of the

mandibular teeth with a stone.

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6. Examine the balancing contacts in a similar manner and adjust the lingual cusps

of the maxillary teeth or the buccal cusps of the mandibular teeth to corrective

defective contacts.

7. After completing the selective grinding, move the articulator into the various

positions, and check the occlusion into the various positions, with tissue paper

strips. Now the incisal guide pin should contact the incisal guide table and there

by indicate reestablishment of the original vertical dimension of occlusion. Do

not complete definitive polishing of the Occlusal surfaces of the teeth at this time

because the dentist usually remounts the dentures on the day of insertion.

8. Recheck the occlusion on the articulator in the centric relation position using

articulator paper, and evaluate the pattern of contacts. Equalize the contacts on

the right and left sides to assure a uniform distribution.

Correction of Occlusal discrepancies by selective grinding:

In order to produce a satisfactory result it is important to carry out the selective

grinding systematically to ensure that.

1. Vertical dimension is maintained.

2. An even distribution of occlusal stress is obtained in centric occlusion.

3. An even distribution of stress is maintained in lateral positions.

The vertical dimension is controlled by the lower buccal cusps and the upper

palatal cusps and their opposing fossae there fore it is essential that these zones must

receive careful consideration when establishing centric and lateral occlusion.

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Grinding into centric occlusion:

Place thin blue articulating paper on the Occlusal of the lower teeth and close the

articulator for with sufficient pressure to record just the first contact areas. Observe the

prominent cusp or cusps and decide whether the cusp or its opposing fossa should be

ground by checking this cusp in its lateral working position and then its balancing

position. If the offending cusp makes premature contact in both centric and lateral

working positions then the cusp and not the fossa should be ground to produce even

centric occlusion. When, however, a cusp producing premature contact in the centric

position does not cause premature contact when in working and balancing positions then

the fossa is ground to accommodate the cusp. (The lateral contacts can be marked with

red articulating paper for purposes of differentiate on this principle is followed until an

even centric occlusion is obtained through out the dentition.

Grinding in for Lateral excursions:

To enhance the retention and stability of the dentures and to reduce the stress applied to

the Alveolar ridges of the mandible moves laterally, it is most important to provide a free

sliding lateral articulation and elimination of cusp lock.

Red articulating paper is placed between the occlusal surface of the teeth and the

dentures moved with light pressure from centric occlusion into right lateral occlusion. If

the upper and lower buccal cusps make premature contact and balancing side is out of

occlusion then the upper buccal cusp is ground as the lower buccal cusp is required to

maintain vertical dimension and even pressure in centric occlusion when the lower

lingual and upper palatal cusps occlude prematurely in this lateral position the lower

lingual cusp is ground to produce balance of both sides of the denture. The upper palatal

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cusp is required for the maintenance of vertical dimension in centric occlusion. The

grinding of the buccal upper and lingual lower cusps to produce balance in lateral

movements is often referred to as grinding to the “Bull” rule.

Should the balancing side exhibit premature occlusion between the lower buccal

cusp and the palatal upper cusp it will be necessary to grind the palatal upper cusp and

not the lower buccal cusp since this cups is required to maintain vertical dimension and

even pressure is centric occlusion and contact in the working lateral position.

The procedure having been completed for the right lateral position it is then

repeated for the left lateral excursion having established a free lateral sliding movement

of the occlusion of the protrusive contacts is studied.

Correction of contacts in protrusion:

As we are dealing with an artificial dentition, and are not concerned with the possible

over eruption of teeth as may occur with a natural dentition. Most of the grinding for

correction of premature contacts of incisal edges of anterior teeth, when in protrusive

occlusion, can be carried out at the expense of the lower incisors. A limited amount of

grinding lower of the upper anterior teeth to simulate attrition, related to the patient’s age,

can enhance the appearance of the dentures.

Perfecting Articulation with Grinding-in paste:

The main correction of occlusal irregularities must be carried out with small mounted

abrasive stones in a hand-piece so that the vertical dimension is kept under control. The

amount of adjustment made with grinding-in paste must be small as this will reduce all

occluding surfaces and if excessive will result in loss of vertical dimension. A paste of

course grit carborundum powder mixed one with Vaseline or tooth paste is used first.

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Followed by one of fine grit carborundum to smooth the previously ground tooth surfaces

and produce a perfectly even occlusion.

Reduction of sharp edges of Ground teeth:

On completion of all grinding, sharp edges present buccally and lingually must be

rounded to prevent tongue and cheek irritation rubber wheels, water of Air stone, and

finally pumice paste used with polishing brushes will produce a smooth finish.

Advantages of Remounting and Selective grinding:

The Patient remount method is to remount the dentures on articulators.

1. It reduces patient participation.

2. It permits the dentist to see better what he is doing.

3. It provides a stable working foundation; bases are not shifting on resilient tissues.

4. The absence of salvia makes possible more accurate markings the articulating

paper or tape.

5. Corrections can be made away from the patient, thus preventing occasional

objections when patients see their dentures being ground.

Removing Dentures from Cast:

After correction of processing error and construction of a face-bow index if requires, the

dentures are ready for removal from the cast and finishing and polishing.

Procedure for removing dentures from cast:

1. Using a cast trimmer, thin the casts with the dentures seated on them, but avoid

trimming the denture base.

2. Remove the stone from the denture in small sections. Use a bur or a saw

judiciously in removing the stone in sections without damaging the dentures.

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3. A shell blaster also is useful in removing stone from the interior of the denture.

4. A pneumatic chisel aids in removing stone from the denture however, Great care

is essential to prevent damage to the denture. Particularly to the denture teeth.

Do not attempt to pry the denture from the cast because it can result in fracturing

the denture. After removal from the cast, the dentures are ready for finishing and

polishing.

Various abrasives that are used for finishing and polishing Procedures of Complete

denture

Abrasives are rough gritty and wear producing particles .abrasive is a substance which is

used to remove excess material by cutting. Substance used to grind objects in order to

give them desired size, shape or finish.

Pumice: A substance of volcanic origin consisting chiefly of complex silicates of

aluminum, potassium and sodium occurring as a very light, hard, porous grayish powder.

It is used as a polishing agent. The effect will be depending on particle size. It is used

for smoothening of denture base and polishing teeth in mouth.

Chalk: Chalk is calcium carbonate prepared by a precipitation method. There are various

grades of physical forms of calcium carbonate available for different polishing technique.

It is used for polishing denture base.

Sand: Sand particles consist of small grains of Silica (SiO2) it is formed by the

decomposition of sand stones due to various effect of weather.

Types are: Pit Sand, River Sand, Sea Sand.

Sand should contain sharp, angular and durable grains. It is used in the form of sand

paper.

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Finishing & Polishing instrument.

1. Finishing burs: It should at least 12 fluted, however some of them are 40 fluted.

They may be made up of stainless steel or tungsten carbide. They wont cut the

restorative materials, but only removes excesses creating a smoother surface.

2. Paper carried abrasives: These are usually sand cuttle garnet or baron carbide.

Guide to paper disc or strips the paper disc should be attached to mandrel.

3. Brushes: They will be available in different forms like wheels, cylinders, cones.

4. Rubber: Plain rubber ended rotary tools are essential for any polishing procedures.

They will be available in different shape. E.g.: Cups, Wheel, cones.

5. Cloth: Cloth carried on a metal wheel is used in final stages of polishing, either

with or without a polishing medium.

6. Felt: Different shape of felt is wheel, cone and cylinders usually with polishing

agents.

Polishing the Complete Denture:

Two methods of polishing complete dentures will be presented.

Method used for Polishing of the Complete Denture.

1. After taking the complete denture from the cast use a shell blaster to remove any

stone that adheres to the denture take care to avoid burning the surface of the

acrylic resin shell blasting.

2. Trim the flash from the complete denture with an arbor band or a large bur

mounted on a laboratory lathe.

3. Finish the frenum attachments with a small carbide bur to create the desired

freedom.

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4. With a chisel carefully remove stone adhering to the gingival margins. Make a

chisel by grinding a broken Instrument to form sharp triangular edges which

facilitate the removal of stone from the gingival margin.

5. Check the interior of the denture carefully with a finger. Locate any modules of

acrylic resin and remove them with a round bur.

6. Complete the relief for the frenum attachment by using No. 558 or a No. 771 bur

to do the final finishing and to open the frenum attachment.

7. Finish the lingual border area of the mandibular complete denture with a hand

piece-mounted small carbide bur. Frequently a standard size arbor band is too

large for this area.

8. Thin the palate if necessary take care to avoid producing grooves when using an

arbor band. A large lathe-mounted Laboratory bur also is useful for these

procedures.

9. Pumice the dentures with a prepared rag wheel.

Preparing rag wheel: Special preparation of a rag wheel makes it more effective for

pumicing and polishing. The procedure described also conditions used rag wheels by

giving them the flexibility and flutiness necessary to achieve a smooth finish.

Procedure:

1. Place the rag wheel on a spiral chuck, run the lathe at low speed, and use a knife

to cut the threads holding the rag wheel plies together. Hold the knife firmly

while cutting the threads.

2. Stop the lathe, separate the plies of the rag wheel and make certain to cut the

thread completely.

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3. With the rag wheel on the spiral cheek rotate the lathe low speed and hold a

stainless steel plaster spatula against the rag wheel to remove the cut threads and

make the wheel fluffy.

4. Single the strayed threads with a lighted match to make the wheel uniform. Place

a metal pan beneath the wheel, and have the lathe and any suction device in the

non operating position. Have a bowl of water available to douse the wheel if it

flares.

5. After placing the rag wheel in water, return it to the lathe and start the lathe at low

speed. Rotate the singed wheel against the stainless steel spatula again to fluff it

and remove any remaining threads.

6. Modified rag wheel is ready for use.

Pumicing denture:

Procedure:

1. Make slurry of fine flour of pumice with water, using copious amounts to the

slurry, wet the rag wheel and polish the denture at low speed more the denture

throughout the polishing to prevent formation of plane surface. Use a brush or

prophy cup with slurry to polish areas less accessible to the rag wheel.

2. Polish the palate and areas of the denture not readily accessible to the rag wheel

by using a prophy cup or a Dixon brush with slurry of flour of pumice smooth the

denture in this manner because a larger polishing instrument would obliterate

anatomic details. After completing the pumicing wash the denture thoroughly in

water, dry it and examine it for scratches. It any scratches are visible on the

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pumiced surface. Repeat the pumicing and post pone the high polishing until

after removing all scratches.

3. Stipple the denture with a No. 200 finishing bur Rotate this bur slowly in a hand

piece and hold it in light contact with the surface of the denture to be stippled that

is, the area of the attached gingiva. Use light random circular movement of the

bur against the resin surface to produce an egg shell or stippled, effect that breaks

up light reflections and corrects minor imperfections in the resin.

4. Go over the stippled area lightly with a rubber prophy cup and slurry of flour of

pumice.

5. Put a high shine on the denture with No. 341 Tigeleam or prepared chalk slurry

and a modified rag wheel. Do not use this rag wheel with any other polishing

material. Examine the denture carefully for scratches and polish out any missed

previously. Take care when polishing or pumicing the denture to keep from

abrading anatomic details of the plastic teeth.

6. Brush the denture with green soap to remove all traces of polishing material, and

examine the denture carefully rinse the denture in water, and store it in a plastic

container of water until needed.

Method II for Polishing the complete denture

1. Remove the denture from the cast.

2. Remove the stone that adheres to the gingival margin area of the denture with

bard-parker handle and a No. 25 blade. Trim away excess flash with a Laboratory

Lathe-mounted carbide bur place the denture in an ultrasonic cleanser containing

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a solution for removal of gypsum products. Adjust for frenum clearance with No.

558 bur mounted in a Laboratory Lathe.

3. Use a rubber point mounted on a mandrel and a dental lathe to remove scratches

from the denture base in areas in accessible to the larger pumice wheel. Pumice

the denture using flour of pumice or fine pumice mixed with water and a modified

rag wheel as described previously.

4. Polish areas between the teeth with a bristle brush and pumice slurry.

5. Put the initial high shine on the denture with a soft rag wheel and prepared chalk

mixed with water.

6. Put the final high shine on the denture with a soft chalmois wheel and gold rouge.

7. Stipple the denture with a straight hand piece No. 4 round bur bent slightly to

rotate eccentrically.

8. Place the bur in a lathe and with the lathe running at slow speed; stipple the

surface of the denture base in a random motion. Apply a high polish to the

dentures again, scrub them with soap and water and place them in a container of

water until ready for use by the dentist.

Polishing ‘Teeth’:

Acrylic resin teeth are polished by the same method as the denture base material. A

rubber prophy cup and fine pumice or flour of pumice is used to restore the surface luster

of acrylic teeth after modification. A high luster is restored to the surface of these teeth

with a soft rag wheel and a high-shine material, such rouge or prepared chalk slurry.

Care should be taken when polishing resin teeth to avoid removing too much material

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from the Occlusal surfaces and thereby, effecting the occlusion. One disadvantage of

using plastic teeth by inadvertent contact between teeth and polishing wheel.

A technique for finishing and polishing denture bases William A Welker, D.D.S.,

M.S.D., Donal C Kramer, D.D.S., M.S. and Roger W. Mercer USAF Medical center,

wright wright patterson AFB, Ohto.

A common complaint of denture wearers is that they are unable to keep their dentures

clean and free from stains. This results from improper home care by the patient or

improper finishing of the art portion of the denture. T alleurate this common complaint

patients should receive explicit instructions in home care, and dentures should be finished

and polished so that they are free ali surface,scratches and imperfections.

When the dentures are poorly finished food debris will not be trapped on the surface, thus

preventing objectionable odor, and taste and an unsightly appearance.

The following technique proven successful in producing blemish-free dentures:

Materials and Method:

1. Deflask the dentures and remove the resin flash from the borders.

2. Use chisels to remove excess acrylic resin or stone from around the necks of the

teeth. The chisels should include one with a right bevel, one with left bevel, one

with a fine point. They are easily made from old dental hand Instrument.

3. Smooth the interproximal spaces, papillae and rugae area with a soft bristly brush

and flour of pumice large brushes and rag wheels destroy the anatomy and should

not be used.

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4. Polish the cervical surface of each artificial tooth with a rubber polishing cup.

This will produce smooth surface at the junction of the tooth and acrylic resin. A

region most difficult for patients to keep clean.

5. Remove scratches from the borders with a large rag wheel and pumice.

6. Lightly buff the remainder of the denture base with a rag wheel and pumice.

Light pressure will not destroy the anatomy or the tinting of the denture base.

7. Rinse the denture in water to remove the pumice thoroughly dry, and inspect for

remaining imperfections. It imperfections are visible, repeat the rag wheel and

pumice procedure.

8. Hard-to-reach regions such as the curve of the palate. The rugae area and the

lingual surfaces of lower incisors and canines, are smoothed with midget rubber

points. Followed by pumice applied on a small cotton point made by winding

cotton on a suitable used bur.

9. Wash the dentures thoroughly with soap and water, dry and inspect the base

material under magnification. All denture surfaces, with the exception of the

basal seat area should present a smooth egg shell texture tree of imperfection. If

not the previous steps must be repeated.

10. Apply Ti-gloss to a new rag wheel and lightly buff the denture surface.

11. Wash and dry the denture and again inspect it for imperfection small, hard-to-

reach imperfections are now removed with the rubber points and cotton points

using Ti-gloss.

12. Use Ti-gleem on a rag wheel with a light buffing action to produce on final high

shine.

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Dentures bases finished by this technique will produce highly polished surfaces

free from all imperfections. The denture bases will remain free of stains and odors with

normal home care.

SUMMARY & CONSLUSION :

Method of Retrieval of denture, correction of occlusal discrepancies finishing &

Polishing procedures are discussed in this seminar. These are the end procedures before

the denture is finally deserved to the patient. A little extra effort & time are required for

these & there is not excuse, Which will justly a compromise in these final steps. This

procedure will enhance the comfort, function & esthetics of the denture which is the final

aim every prosthesis is fabricated for.

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Remounting Dentures:

After the index grooves or notches are cleaned the dentures and casts are seated to

the mounting stone with sticky wax. After remounting of denture and casts, occlusal

discrepancies caused during processing.

Every dentist who treats patients with complete dentures is probably aware that

the planned contact relationship of apposing. Posterior teeth are not the same in the

processed dentures as it was before the dentures were processed. Correction of Occlusal

discrepancies should be accomplished at the appointment for the initial placement of the

dentures.

There are two main factors in the production of Occlusal discrepancies in the

processed denture.

1. A change in the relationship of a tooth or teeth to the master cast during

processing procedures.

2. Warp age of the denture base through release of inherent strains when the denture

is separated from the cat upon which it was processed. In the first instance the

tooth may change its relationship to the master cast as a result of investing

procedures (exothermic reaction of investing stone causing an expansion of wax).

3. Cure less packing of acrylic resin in the molds.

4. Improper closure of the flask halves.

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Several methods of processing procedures have been suggested to minimize the risk of

causing such change.

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