RAJIV GANDHI UNIVERSITY OF HEALTH SCIENCES,

BANGALORE, KARNATAKA

PROFORMA FOR REGISTRATION OF SUBJECTS FOR DISSERTATION

1.Name of the candidate and address : Anupama M.S

I year M.D.S student Department of Prosthodontics A.E.C.S Maaruti college of Dental

sciences and Research Centre 108, Tank bund road, Hulimavu,

BTM 6th stage, 1st phase off Bannerghata road, Bangalore - 76

2.Name of the institution : A.E.C.S Maaruti college of Dental Sciences and Research Centre, Bangalore

3.Course of the study and subject : Master of Dental Surgery ( MDS ) Prosthodontics

4.Date of admission to the course : 31-05-07

5. Title of the topic : A comparative study on the properties of putty elastomeric impression materials

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6. Brief resume of the intended work :

6.1 Need for the study:

Elastomeric impression materials have become an essential part of successful

prosthodontic practice. Light and regular body materials have been subjected to

constant evaluation for their properties. However putty consistency elastomeric

impression materials were not scrutinized for their properties. Both for removable

and fixed prosthesis fabrication, putty is used in combination with either light or

regular body consistencies.

Recently putty is increasingly used for border moulding procedure with great

clinical success. The properties of putty influence the final outcome of

impressions but very rarely they are subjected to comparative evaluation. Indian

market is presently flooded with a number of brands and it was found to be

necessary to evaluate the working properties to aid the clinician in selecting

appropriate and quality material.

6.2 Review of literature:

6.2.1 Long-term dimensional stability of three non-aqueous elastomeric

impression materials viz. condensation silicone, polyether and addition curing

polysiloxane, were investigated by James.M.S, Clancy, Scanderret.F.R and

Ettinger.R.L. The testing method was based on A.D.A. specification No. 19. The

impressions of the mould were measured at time zero, 4, 24 and 48 hours and

at 1, 2, 3 and 4 weeks. Impressions poured immediately had the greatest

accuracy for all the materials. The polysiloxane and polyether showed very little

change in dimension after 4 weeks when compared to the test block. However

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condensation silicone showed significant change at 4 h (0.14 mm) and after 4

weeks(0.2mm). After 4 weeks the polysiloxane maintained the best surface

detail, and in polyether it was adequate but the condensation silicone lost much

of its detail in as little as 24 hours.

6.2.2 Sudsukh Thongthammachat, Moore.K, Barco M.T,. Brown D T, Andres

C.J evaluated the influence of impression materials of dental casts made with

different types of trays and impression materials ,poured at multiple times. Two

types of stock trays and 4 types of custom trays were used with addition

polymerizing silicone and polyether impression materials to make impressions of

a metal master model. Each tray and impression material was used to make 5

impressions. Casts were made by multiple pourings at 30 minutes, 6 hours, 24

hours, and 30 days after impression making. Using a measuring microscope, 12

distances were calculated based on measurements of 8 reference points. The

absolute value of the difference of each measurement was calculated . All

deviations in casts made with silicone impression material were within clinically

acceptable range of (<90 µm). For the polyether, distortions occurred that were

clinically unacceptable. Impressions made from polyether distorted over a time.

Silicone impression material has dimensional stability up to 30 days and showed

better dimensional stability than polyether.

6.2.3 Marcinak.C.F, Young.F.A, Draughn.R.A, and Flemming.W.R, evaluated

linear dimensional changes of elastomeric impression materials as a function of

time between taking and pouring of impressions of mounted teeth. Authors have

observed that silicone material produced dies smaller than the teeth, and the dies

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have become dramatically smaller with increasing storage time. Polyether

material produced slightly smaller dies for up to four hours' storage time and then

increasingly larger dies up to 24 hours. The putty wash silicones shrunk away

from the tray and produced smaller dies with increasing storage time.

6.2.4 Kaloyannides.T.M and Kapari.D.J evaluated setting time and consistency

of elastomeric impression materials. mercaptan, silicone, and polyether.

Measurements were made at temperatures of 20 °C, 25 ° C, and 37 ° C. All

elastomeric impression materials tested underwent, in stages, a diminution of the

setting time as the temperature was raised from 20 ° C to 37 ° C. At 37° C putty

silicone materials exhibited a slightly longer setting time of 4.5 to 5.0 minutes and

the functional silicone materials had a setting time of 8.5 to 10.0 minutes.

Regarding consistency, the rise in temperature from 20 ° C to 37° C resulted in a

corresponding diminution of diameter of the sample in all materials with the

exception of the putty and functional silicone materials which exhibited the

greatest diameter at 25° C. The rise of temperature from 20° C to 37 ° C

decreased the setting time and consistency of all materials studied.

6.2.5 Ufuk Hasanreisoglu, Ayhan Gürbüz, A. Nehir Özden ,Fuat Kesim evaluated

reproducibility of the peripheral tissues in edentulous patients. The purpose of

this study was to analyze the effect of different materials and techniques in

current use on the peripheral shaping of the complete denture impressions. The

authors concluded from their study that tissue contours produced by any

impression procedure was not repeatable since all the impression methods in

current use displace the surrounding tissues and details of any procedure can

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only modify this displacement. The validity of multistage border was questioned

by the authors. Simultaneous molding of all borders using putty consistency was

recommended because it reduced the number of insertions of the tray thus

producing a great time and motion advantage. Addition reaction silicone

impression materials polymerized against heavy bodied silicones exhibited good

dimensional stability because of the greater bond strength between materials of

putty and wash consistency. This study proves the necessity for standardization

of the putty consistency impression material as it is used in an emerging

application.

6.2.6 The revised ADA specification no. 19 for non - aqueous elastomeric dental

impression materials was formulated by the Council on dental materials and

devices of the American dental association. This document describes the

sampling and testing procedures for the elastomeric impression materials

mentioned as, physical tests for mixing time, working time, consistency,

compression set, strain in compression, detail reproduction, compatibility with

gypsum, dimensional change and flow. There are no specifications devised

exclusively for putty consistency.

6.3 Objectives of the study :

To compare different brands of putty elastomeric impression materials based

the properties viz. working time, consistency, strain in compression, detail

reproduction and compatibility with gypsum.

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7. Materials and methods :

7.1 Source of data :

Experiments will be conducted to test the properties viz. working time,

consistency, strain in compression, detail reproduction and compatibility with

gypsum according to ADA specification no:19 and the results compiled will serve

as the main source of data.

Materials:

1. Four brands of addition silicone putty impression materials Express ( 3M

ESPE ), Aquasil (Densply), Exaflex (GC), Elite; (Zhermack)

2. Two brands of condensation silicone putty impression materials

Speedex ( Coltene), Zetaplus (Zhermack)

Instruments:

1. Stainless steel plate - to test working time of the impression

material

2. Stainless steel mold - to test working time of the impression

material

3. Spilt stainless steel mold - to test strain in compression

4. Tapered metal ring - to test strain in compression

5. Glass plate - to test strain in compression

6. Ruled block - to test reproduction of surface details and

gypsum compatibility.

7. Impression mold - to test reproduction of surface details and

gypsum compatibility.

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8. Riser - to test reproduction of surface details and

gypsum compatibility

9. Gypsum mold - to test reproduction of surface details and

gypsum compatibility

10.500 gm weight - to test consistency

11.2000 gm weight - to test working time

12.Square metal plate - to test consistency, reproduction of surface

details and gypsum compatibility

13.Water bath - to test strain in compression, reproduction

of surface details and gypsum

compatibility

Equipments:

1. Dial guage

2. Stereomicroscope

7.2 Methodology:

Standard test conditions:

All physical tests will be made under uniform atmospheric conditions of 23 ± 1°c

and relative humidity of 50 ± 5 % . Materials will be mixed according to the

manufacturer’s instructions. All test mixes will be proportioned by weight with a

weighing tolerance of ± 0.1 gram.

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Working time:

A sufficient quantity of material will be mixed according to the standard test

conditions mentioned and placed in a stainless steel mold of 3mm height, 210

mm length and breadth 60 mm , with 6 equally spaced holes of diameter 25.4

mm that pass completely through the mold. The mold is mounted on a flat

stainless steel plate of 3.0 mm thickness and 210 mm length. Each cavity will be

3.0 mm deep and 25.4 mm in diameter. The material will be leveled with a

spatula. Serially numbered disks made of polymethyl methacrylate 16.0 mm in

diameter and 10 mm high will be placed on the material at half minute intervals

according to the schedule. Load of 2000 gm will be immediately applied axially

for 15 seconds using an apparatus equipped with a dial gauge graduated in

0.02mm or less divisions. The load, will then be quickly removed but the disk will

be allowed to remain undisturbed. After the minimum time recommended for

removal from the mouth the height of each disk, in place on the material, will be

read to the nearest 0.02 mm on the dial gauge using a total load of 125 gm, and

recorded as reading B. The material will be stripped from the mold and the disks

will be returned to their original relative positions in the empty mold cavities. The

height of each disk will be read on the dial gauge and recorded as reading A.

B-A=H. The first time at which H becomes equal or greater than (a) 0.20 mm or

(b) twice its value at 1.5 minutes, whichever is greater, is the working time. The

material shall fail if the original value of H at 1.5 minutes is 1.20 mm or more. The

average of three determinations will be reported to the nearest half minute.

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Consistency :

A volume of 0.50 ml of a mix of material will be deposited on a polyethylene- or

cellophane-covered glass plate. 1’30” after the start of the mix, 0.5 ml of material

will be covered with another cellophane or polyethylene sheet and a glass plate

weighing 75± 5 gm, plus a 500gm weight applied axially to the specimen. 12

minutes after the start of the mix, the load (glass plate plus 500gm weight) will be

removed, and the major and minor diameters of the slumped mass of material

shall be measured. The value for the consistency disk will be the average of

three determinations and will be recorded to the nearest millimeter.

Strain in compression:

Specimens will be prepared as follows:

A split, stainless steel mold, with an inner diameter of 12.5 mm, outer diameter

of 26 mm and height of 20 mm, shall be retained by a tapered metal ring which

is 35 mm in outer diameter and 16 mm in height. The mold will be lubricated

with a silicone grease (high vacuum type) to prevent the impression material from

adhering. A sufficient quantity of material will be mixed according to the

manufacturer's instructions. All test mixes will be proportioned by weight with a

weighing tolerance of ± 0.1 g and placed into the mold by means of a spatula. A

sheet of polyethylene followed by a square metal plate shall be brought in

contact with each end of the mold using a clamp, thus exuding excess material

from the mold.

At 1.5 minutes from the start of mix, the mold and accompanying plates shall be

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immersed in a water bath of temperature 32±1°C. The mold and plates will

remain in the water bath for the minimum time recommended by the

manufacturer for removing the impression material from the mouth. Six minutes

after removal from the water bath, the specimen will be placed in a suitable

instrument consisting of an apparatus with a dial indicator, screw, ratchet and

specimen holding platform and will be subjected to a load calculated to produce

a stress of 100 g/cm². Thirty seconds later, the dial indicator, graduated in 0.02

mm, or less, will be read. This value will be reading A. Sixty seconds after

application of a stress of 100 g/cm², an additional load calculated to produce a

total stress on the specimen of 1,000 g/cm² will be gradually applied during an

interval of ten seconds. Thirty seconds after initiation of the stress of 1.000 g/cm²,

a reading of the dial indicator will be taken. This value will be reading B. The

difference between readings A and B, divided by the original length of the

specimen and multiplied by 100, will be recorded as the percentage of strain

between the stresses of 100 and 1,000 g/cm². The height of the mold (20.0 mm)

will be considered to be the original length of the specimen. The value for strain

in compression will be the average of three determinations and shall be recorded

to the nearest 0.1%.

Detail reproduction and compatibility with gypsum

The apparatus required for testing detail reproduction, compatibility with gypsum

and consists of a stainless steel ruled block, which is cylindrical and 31mm in

height, having a raised platform 3mm in height, with a inner diameter of 29.970

mm, an outer diameter of 38 mm. the raised platform will be grooved with 3

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vertical lines x, y , z in which lines x and z will be 2.5 mm from the centre and y

will run through the centre of the platform, two horizontal lines one on each end

namely c d and c’ d‘ at a distance of 12.5 mm from he centre of the platform will

be made.

A stainless steel impression mold, having an outer diameter of 38 mm and inner

diameter of 30 mm, is used.

A riser of diameter 29. 970 is used.

A gypsum mold , 20 mm in height, 41 mm in outer diameter, 30mm in inner

diameter, having 38. 040 mm inner diameter on the other end ,which has a 5 °

taper is made.

Detail reproduction:

The apparatus required to prepare the specimens consists of a ruled block and

mold . The mold will be lubricated with a quantity of mold release agent such as

high vacuum silicone grease. The ruled block will be cleaned with a solvent

before use. If the test material adheres to the block, the block can be lightly

dusted with talcum powder and the excess talcum powder blown away as an aid

to separation.

Test procedure: mold is placed on the test block . The impression material to be

tested will be mixed according to manufacturers instructions and placed into the

mold by means of a spatula 1.5 minutes after the start of the mix. The mold will

be immediately covered with a thin sheet of polyethylene followed by a rigid, flat,

metal plate, and a sufficient force will be applied to seat the plate firmly against

the mold. The assembly will be immediately transferred to a water bath at 32 ±

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2°C. Three minutes after the minimum time recommended by the manufacturer

for removal of the impression from the mouth , the mold and test block will be

separated. The reproduction will be considered satisfactory if a line of 0.075 mm

width is reproduced continuously for the full 25 mm between cross lines in at

least two of three specimens prepared. Observation will be made immediately

after separation under stereomicroscope

Compatibility with gypsum:

After the separation of the test specimen formed and tested in the detail

reproduction mold will retain the specimen. Mold is placed over riser and gently

pressed down to force the specimen up so that the ruled surface of the specimen

will be in level with the top of mold . Part will be fitted to . The gypsum mold will

be lubricated with a quantity of mold release agent such as silicone high vacuum

grease to facilitate removal of the poured impression. Ten minutes later. a

gypsum slurry will be poured against the impression with gentle vibration to

completely fill the mold. The gypsum used will be unmodified alpha calcium

sulfate hemihydrate. adjusted to give a setting time of 10±3 minutes by the

addition of calcium sulfate dihydrate. The poured impression will be stored in air

at 23.0 ± 2.0°C and 50 ± 10% relative humidity for 30 minutes. The gypsum cast

will be separated from the impression material and examined under

stereomicroscopy. The reproduction will be considered satisfactory if a line of

0.075 mm is reproduced continuously for the full 25 mm between cross lines in at

least two of three specimens prepared.

The results will be subjected to statistical analysis.

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7.3 Does the study require any investigations or interventions to be

conducted on patients or other humans or animals ?

No

7.4 Has ethical clearance been obtained from your institute ?

Yes

7.5 Trial test done if any ?

Yes

8. Signature of the candidate

9. Remarks of the guide : Putty consistency silicone impression materials

were not compared for their properties. The results will help the clinician

to select appropriate material.

10. Name and designation of

10.1 Guide Dr K Chandrasekharan Nair

Professor of Prosthodontics

10.2 Signature

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10.3 Co- Guide if any

10.4 Signature

10.5 Head of the department Dr. K Chandrasekharan Nair

10.6 Signature

11 . 11.1 Remarks of the principal

11.2 Signature

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LIST OF REFERENCES

1. James M.S, Clancy, Forrest . R, Scandrett, Ronald L ; Long term

dimensional stabilityof three current elastomers ; J Oral Rehabilitation 1983 ;

10 : 325-333

2. Sudsukh Thongthammachat, Moore.K, Barco M.T ; Brown D T, Andres C.J,

Hovijitra .S ; Dimensional accuracy of dental casts : influence of tray material,

impression material and time ; J Prosthodontics 2002 ;11: 98- 108

3. Marcinak.C.F, Young.F.A, Draughn.R.A, and Flemming.W.R ; Linear

dimensional changes of elastomeric impression materials ; J Dent Res 1980 ;

59 :1152- 1155

4. Kaloyannides.T.M and Kapari.D.J ; Setting time and consistency of elastomer

impression materials ; J Dent Res 1974 : 653- 656

5 Ufuk Hasanreisoglu, Ayhan Gürbüz, A. Nehir Özden ,Fuat Kesim ;

Reproducibility of the peripheral tissues in edentulous patients ; Tr. J.of Medical

Sciences 1998 ;28 : 291-294

6. Reports of council and bureaus; JADA 1977 ; 94

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REPORT ON THE PILOT STUDY

A comparative study on the properties of putty

elastomeric impression materials .

Objectives of the study:

To compare different brands of putty elastomeric impression materials based on

the properties viz. working time, consistency, strain in compression, detail

reproduction and compatibility with gypsum.

Methodology :

In the pilot programme the test for detail reproduction and compatibility with

gypsum was done. The apparatus for detail reproduction and compatibility with

gypsum was made using the test methods prescribed by the ADA specification

no : 19, which consists of the following:

1. A ruled block having a height of 31mm, the outer diameter of the ruled

platform is 38mm and the inner diameter being 29.970 mm, the width of vertical

lines x, y, z is 0.075 mm and the width of the horizontal lines c d and c’ d’ is also

0.075mm, the lines x., y , z are 25mm in length & line y passes through the

centre, lines x & z are 2.5 mm from the centre . Lines c d and c’ d’ are at a

distance of 12.5mm from the centre. It is made of stainless steel.

2. An impression material mold with outer diameter of 38 mm and inner

diameter of 30 mm, with a height of 6mm is made of stainless steel

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3. A riser with a diameter of 29.970 mm, and height of 3mm. It is made of

brass.

4. A gypsum mold with an outer diameter of 41 mm and inner diameter of 30

mm, which tapers 5 ° to a diameter of 38 mm. It is made of brass. A rigid flat

metal plate, polyethylene sheets, a water bath, talcum powder & silicon grease

was used during the procedure.

5. For the pilot study, two brands of addition silicone ( Express STD and

Exaflex ) and two brands of condensation silicone ( Speedex and Zetaplus ) were

used.

Detail reproduction :

The mold was lubricated with a quantity of mold release agent, the ruled block

was dusted with talcum powder and the excess was blown away, to aid to

separation. The mold was placed on the test block . The impression material to

be tested was mixed according to manufacturer’s instructions and placed into

the mold by means of a spatula, 1.5 minutes after the start of mix. The mold was

then immediately covered with a thin sheet of polyethylene followed by a rigid,

flat, metal plate, and a sufficient force was applied to seat the plate firmly against

the mold. The assembly was immediately transferred to a water bath at 32 ±

2°C, 3 minutes after the minimum time recommended by the manufacturer for

removal of the impression from the mouth, the mold and test block were

separated. Five impressions of the ruled block were made in this way with each

brand. Observation was made immediately after separation using

stereomicrosope. The average result of measurements were determined .

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Compatibility with gypsum:

After the separation of the test specimen formed and tested in the previous

procedure for testing, detail reproduction, the mold with the test specimen was

placed over riser and gently pressed down to force the specimen up so that the

ruled surface of the specimen is in level with the top of mold . Gypsum mold was

fitted to impression mold, and lubricated with a quantity of mold release agent to

facilitate removal of the poured impression. After ten minutes gypsum slurry was

poured against the impression with gentle vibration to completely fill the mold.

The gypsum used was unmodified alpha calcium sulfate hemihydrate. The

poured impression was stored for 30 minutes. In the same way impressions were

poured and casts of each specimens were obtained. The gypsum cast was

separated from the impression material and examined under stereomicroscope.

The average result of measurements were determined .

Lines X, Y and Z are 24 mm in length from one cross cut o another cross cut and

lines X and Z are at a distance of 2.5 mm from the centre.

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X24 mm

Y24 mm

Z24 mm

Results

I. Reproduction of surface details:

The mould had three lines designated as x ,y ,z. Each line had a length of 24 mm

from one cross cut to the other cross cut. Line copied in the impression is

measured and shown in the table.

a. Addition silicone

Brand: Express STD

Specimen Time in water bath (min)

Measure of lines (mm) X Y Z

1 7 23.75 24 23.75 2 7 24 24 24 3 7 23.75 23.50 23.75 4 7 24 24 24 5 7 24 23.75 24

Mean: 23.88 mm

Brand : Exaflex

Specimen Time in bath (min)

Measure of lines (mm) X Y Z

1 7 23.50 23.75 24 2 7 24 24 24 3 7 24 24 24 4 7 24 24 24 5 7 24 24 24

Mean: 23.95 mm

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b .Condensation silicone

Brand :Speedex

Specimen Time in bath (min)

Measure of lines ( mm)

X Y Z 1 5 23.75 23.75 24 2 5 24 24 24 3 5 24 23.75 24 4 5 24 24 24 5 5 24 23.75 24

Mean: 23.92 mm

Brand :Zetaplus

Specimen Time in bath (min)

Measure of lines (mm)

X Y Z 1 6 24 23.75 24 2 6 24 24 24 3 6 24 24 24 4 6 23.75 24 23.75 5 6 23.75 23.75 23.60

Mean : 23.86 mm

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COMPATIBILITY WITH GYPSUM:

Dental stone was poured on the impression and the cast was retrieved. The lines

were measured on each cast as in the impression.

a. Addition silicone

Brand 3M

Specimen Measure of lines

X Y Z 1 24 24.75 24 2 24.25 24 24.25 3 24.50 24 24 4 24.50 24.50 24 5 24.25 24.25 24.50

Mean : 24.20 mm

Brand Exaflex

Specimen Measure of lines

X Y Z 1 24 24 24 2 24 23.50 23.75 3 23.75 24 24 4 24 24 24 5 24 24 24.75

Mean : 23.95 mm

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b. Condensation silicone

Brand Speedex

Specimen Measure of lines

X Y Z1 24 24 242 23.50 23.50 243 24 23 22.754 24 24.25 24.255 24 24 23.50

Mean : 23.78 mm

Brand Zetaplus

Specimen Measure of lines

X Y Z1 23.75 23.75 23.752 24 24 243 23.75 23 23.754 24 24 245 23.50 23.50 24

Mean : 23.77 mm

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Results :

Mean of the measurements obtained from test for detail reproduction and

compatibility with gypsum.

Brand Impression Casts

Express STD 23.88 mm 24.20 mm

Exaflex 23.95 mm 23.95 mm

Speedex 23.92 mm 23.78 mm

Zetaplus 23.86 mm 23.77 mm

Conclusion :

Exaflex exhibited good reproduction of surface details and better compatibility

with gypsum product.

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