skill lab presentation

8/7/2019 SKILL LAB PRESENTATION

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APRISIA WAWORUNTU

SKILL LAB PRESENTATION RESULT

ALGINATE & GYPSUM



HIDROCOL IRR. LAB SKILL - AIM

Appropriate

Manipulation

Measure

the Setting time

Measure

the Alteration of

alginate dimension ;

If alginates treated in

different condition.



*REVIEW

ALGINATE

Material Composition :

Source : Annusavice. Phillips, Science of Dental Materials p. 240

Component Function Weight Percentage

Potassium Alginate Soluble alginate 15

Calcium Sulfate Reactor 16

Zinc Oxide Filler Particles 4

Potassium Titanium Fluoride Accelerator 3

Diatomaceous Earth Filler Particles 60

Sodium Phosphate Retarder 2



*REVIEW

MANIPULATION

Prepare a proper

mixture of water and

powder.

Sift the water into

the rubber bowlthen the powder

afterwards.

Mix carefully with

spatula for about 45

sec to 1 min.

Smooth, creamy

mixture

Source : Mc Cabe, John. Applied Dental Materials.



RESULT.



SETTING TIME

1st Experiment 2nd Experiment 3rd Experiment

Hydrocol Irrev. Alginate Alginate Alginate

W/P ratio 2:1 2:1 2:1

Water (ml) 50 50 50

Powder (gr) 22 22 22

Initial Setting (sec) 60 60 60

Final Setting (sec) 10 10 10Setting Time (sec) 120 110 100



Agio :

10 sec.

Average Setting Time :

120 + 110 + 100 = 340 sec ÷ 3 = 113 sec



DIMENSION ALTERATION1st

Experience

2nd

Experience

3rd

Experience

4th

Experience

5th

Experience

W/P Ratio 2:1 2:1 2:1 2:1 2:1

Water (ml) 50 50 50 50 50

Powder (gr) 22 22 22 22 22

Do (mm) 35 35 35 37 37

Dt (mm) 35 (24hr) 33.5 (30min) 37 (60min) 37 (24hr) 37

D (mm) 0 -1.5 2 0 0

Condition :1st and 2nd = air.

3rd to 5th = kept in water.



CONCLUSION

Alginate, if treated and kept in different ways

will cause changes in its dimension.

In the air , alginate dimension becomes shrink ; a

process being called as syneresis.

In the water , alginate absorbs water and

expands its dimension ; a process being called asimbibe.



GYPSUM SKILL LAB - AIM

Appropriate

ManipulationMeasure

Setting Time and

Material Setting

Expansion of Gypsum



*REVIEW

GYPSUM

(CaS04. 2H20)

mineral mined used for making model and die;as an important auxiliary materials for dental

laboratory operations that are involved in the

production of dental prostheses.



*REVIEW

The current ISO Standard for Dental Gypsum Productsidentifies five types of material as follows:

Type 1

Dental plaster, impression

Type 2Dental plaster, model

Type 3

Dental stone, die, model

Type 4Dental stone, die, high strength, low expansion

Type 5

Dental stone, die, high strength, high expansion



*REVIEW

CONTROL OF SETTING TIME :

IMPURITIES FINENESS

W/P RATIO

MIXING

TEMPERATURERETARDER &

ACCELERATOR

Source : Annusavice. Phillips, Science of Dental Materials



MANIPULATION

Prepare a proper

mixture of water and

powder.

Sift the water intothe rubber bowl

then the powder

afterwards.

Mix carefully with

spatula for about 20

sec to 1 min.

Smooth, creamy

mixture

Vibrate the

mix to avoid

porosity

Circular

stirring motion

Source : Mc Cabe, John. Applied Dental Materials.



RESULT.



SETTING TIMEDENTAL PLASTER

Treatment W/P Ratio Water

(ml)

Powder

(gr)

Initial

Setting (s)

Final

Setting (s)

Setting

time (s)

1st 30 : 75 30 75 159 52 271

2nd 35 : 75 35 75 213 26 299

3rd 40 : 75 40 75 389 213 662

4th 45 : 75 45 75 962 266 1288

5th

50 : 75 50 75 851 1662 2573



CONCLUSION

Ascended Pattern found :

T he more water ratio added toward powder

ratio, the more time needed for setting process.

Hemihydrate Dihydrate

water

as retarder+ Thermal



Thank you

³IT¶S LEARNING BY DOING´

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