alginate impression material

8/10/2019 Alginate Impression Material

1/92


2/92

WELCOME TO

DENTAL MATERIALS IRESD2012

Dr. Fred Berry


3/92

WELCOME TODENTAL MATERIALS I

RESD 7022012

Dr. Fred Berry


4/92

Hope you had aMERRY CHRISTMAS

HAPPY NEW YEARand a

Restful Time off


5/92

PLEASE WRITE YOUR NAME ONTHE FRONT OF YOUR MANUAL

NOW!!

THANKS!!!!


6/92

Manual PAGE # 1

Schedule Page # 3

Course Texts Page # 6

PLEASE WEAR LAB JACKETSAND NAME TAGS


7/92

Why Dental Materials?

Learn the basic materials utilized infuture lab courses and on clinic prior tograduation

Questions on National Board Part II Exam Daily / hourly use in dental practice

Familiarity with materials is essential to

quality dental treatment Using a material incorrectly = FAILURE

loss of income & unnecessary trauma to

your patient


8/92


9/92

REVERSIBLE AGARHYDROCOLLOID

(will be discussed later with theElastomeric Impression Materials)


10/92

I. Introduction(terminology)

A. Impression material: Used to make anaccurate replica ofthe oral tissues

B. Impression: A negativereproduction of the

oral tissues


11/92

C. Impression Tray: A metal or plastic device into which the material

is placed, carried to the mouth, allowed to set,supported and then removed.

Types:

All plastic perforated or non-perforated Metal rim-lock or perforated


12/92

D. Model or Cast A POSITIVE produced by filling an

impression with a hard setting gypsummaterial

Used in the evaluation and fabrication of

restorations or prostheses


13/92

II. Desirable Properties of anImpression Material


14/92

(1) should be elastic:

exceptions: Impression Plaster, ZOE,Compound

(2) pleasant odor, taste, and color

(3) non-toxic or irritating (4) adequate shelf life

(5) economical

(6) easy to use with minimum equipment (7) good setting characteristics

(8) good consistency and texture


15/92

(9) readily wets the oral tissues

(10) removed without permanent

deformation or damage (11) adequate strength

(12) dimensionally stable

(13) compatible with various cast and diematerials

(14) accurate

(15) able to be disinfected


16/92

III. Composition of Alginate Powder


17/92

III. Uses of Alginate Material:

Impressions and Models for: diagnostic (study) models construction of custom trays & bite

blocks construction of prosthetic temporary

crowns,bridges or appliances

fabrication of a quick model to check the

progress of a crown/bridge preparation simple transfer impressions

and many other uses where needed


18/92

IV. Setting Reaction Potassium Alginate + Calcium Sulfate Dihydrate

(POWDER)+ H20 =Calcium Alginate GEL + SodiumSulfate

Sol to Gel Phase POWDER + WATER

IRREVERSIBLE REACTION


19/92

V. Physical Properties

A. WORKING TIME:time you haveto work with the material before it

sets

Regular set:2 minutes (60 sec. mix time) Fast set:1 minute (45 sec. mix time)

Affected by:

increase temp colder temp

mixing time

w/p ratio


20/92

B. Setting Time: Regular set = 4 minutes from start of mix

Fast set= 2 minutes from start of mix Affected by:

increase water temp 10 degrees = 1/2

set time (setsfaster) decreasewater temp(cold) = longer setting time(sets slower)


21/92

C. Flexibility(elasticity): able to be removed after set (elastic)

Is limited - should block out major undercuts

D. Strength: tendency to tear - remove with SNAP motion

avoid thin areas - need 3 - 4 mm thickness

E. Compatible withmost Gypsum

Products suchas


22/92

F. Dimensional Stability(Loss ofaccuracy with time of storage)

Syneresis: water collects on the surface

evaporates causing shrinkage Avoid by:

pouring ASAP

storingcorrectly


23/92

Imbibition:

absorption of water causes expansion or swelling

avoid by:

pouring ASAP

storing correctly


24/92

G. Permanent Deformation Once seated no pressure should be

exerted Needs adequate thickness (3-4 mm)

Tray size very important

Tends to slump - build up with wax forhigh palates

highest deformation

of allimpressionmaterials


25/92


26/92


27/92

H. Surface Reproduction

Registers the detail of the soft tissue,restorations and fractured teeth

Not adequate for fine detail of

preparations


28/92

I. Summary:

Slight initial expansion Slight initial contraction

Loss of accuracy with time of storage

STORAGE--up to 2 hrs @ 100% humidity: Cover with moistpaper towel

Place in plastic bag & seal

POUR ASAP Powers & Wataha; Dental Materials Properties and

Manipulation 9th edition: modern materials usuallycan be stored at 100% humidity for up to 5 days

without serious dimensional changes.


29/92

V. Clinical Technique

A. Patient position & instruction: Upright position, have saliva ejectorready

Brush, rinse one minute with mouthrinse Wipe teeth & soft tissue of excess saliva

with a gauze pad


30/92

B. Tray Selection

Correct size:

Comfortable - not impinge on the tissuecheck:

Maxillary Molars (facial)

Mandibular Molars (lingual) Always better to be slightly larger


31/92


32/92

Adapt & Extend with wax when needed


33/92

Wax extends tray borders & allows for border molding


34/92

C. Equipment Needed


35/92

D. Water Temperature & Amount

70-75 degrees

Add water to the bowl first

1 - Full cylinderper pack


36/92

E. Dispensing

Read Instructionson the productfirst Accurate water powder ratio is critical

Alterations will affect the strength,viscosity, setting time, consistency,flexibility, tear strength and surface

detail It is no longer necessary to fluff thebulk container.

Do not pack the scoop tightly


37/92

F Mi i


38/92

F. Mixing Add powder to measured water

Use a clean bowl as gypsum particles will cause adecrease in the setting time of the alginate

Regular set:Mix 45 to 60 seconds

Fast set:Mix 30 to 45 seconds Under mix= weak gel, poor surface

texture, loss of detail, unmixedpowder

Over mix= decrease workingtime, loss of detail, incompleteseating of the tray

Th hl i i th id f


39/92

Thoroughly mix using the side ofthe rubber mixing bowl

Have separate bowl and spatula only foralginate

Particles of gypsum products will affect

the working and setting times (lessworking time and faster set)

G L din th tr


40/92

G. Loading the tray Avoid trapping air if using a solid tray

Place more in the anterior Apply excess in areas of common voids

Maxillary molars, palate, anteriors under the

lip, occlusal surfaces Linguals of Mandibular molars, anteriors

under the lip, occlusal surfaces


41/92

Incorrect w/p ratio produces runny mix = discard

Correct w/p ratio


42/92


43/92


44/92

Seat tray fully allowing the alginate to moveforward

Hold in place without pressure or movementuntil fully set

2 minutes after alginate loses

its stickiness 4 minutes from

start of the

mix

( ) l


45/92

I. Tray (impression) removal Grasp tray firmly

Support patient Remove with one snap motion

Break the posterior seal first

Avoid rocking to remove

J I i E l ti


46/92

J. Impression Evaluation Rinse onlywith water if areas of blood or

saliva are present Rinse with slurry before the model is

poured

K C it i


47/92

K. Criteria A. clear negative reproduction of the

teeth,gingival margins, palate,frenum attachments, facial and

lingual vestibules, hamular notches,

palatal vault B. free ofbubbles or voids

in the toothportions

C free of bubbles or voids larger than


48/92

C. free of bubbles or voids larger than0.5 mm in diameter in other areas

D. no evidence of unmixed powder E. surface should be smooth with no

evidence of distortion

F. no tears G. impression should be completely within

the confines

of the tray H. impression

should not be

pulled


49/92

If the Impression is unacceptable,simply remove it from the tray andtry again. It is more difficult to remove

if adhesive has been used and in mostcases a new tray must be used. Onereason for not using it in our lab

project today and Wednesday.


50/92

VI Imp ssi n/M d l Disinf ti n


51/92

VI. Impression/Model Disinfection

1. AntiMicrobial Alginate

2. Use Aseptisol /Water mixture in the

Plaster or Stone inorder to disinfect themodel (found in the

lab) not for our

VII Impression Storage


52/92

VII. Impression Storage

Wrap with a MOISTpaper towel

Place in a plastic bag and seal

Can be stored for up to 2 hours in 100%humidity (Only in extreme situations)

NEVER WITH AN IMPRESSION FOR AFINAL MODEL


53/92

VIII. Model Fabrication

Ideally pour immediately (within 10-15minutes) in the selected Gypsum product

Always keep the impression facing upright

DO NOT AIR DRY!


54/92

VIII. Removal of the Impression fromthe Final Set Model

Remove after one hour Prolonged contact between the Alginate and

Gypsum will cause surface deterioration of the

model Alginate will absorb moisture from the model

Danger of fracture of

the teeth due to thehardness of the Alginatewhen removing theimpression from the model


55/92


56/92

IX. Trouble Shooting

A. Short working or setting time Water temp, w/p ratio, mixing time, time

in loading the tray

B. Grainy surface, lack of detail

Not mixed well, material starting to set,removal before final set

Incorporated air when mixing


57/92

C. Gagging Explain to patient, patient position

Take lower first, use fast set Anesthetic rinses and sprays

Avoid overloading the tray in the posterior

D. Tearing Removal

Size of the tray & presence of severe

undercuts E. Bubbles or voids

Apply some material with finger or syringe

prior to tray placement

X LABORATORY PROCEDURE


58/92

X. LABORATORY PROCEDUREA. Preparation of the Typodont for Impression

Apply SMALL piecesof MOIST paper towelto the proximal areasof all teeth to prevent

tearing of the alginate

Clinically theseareas are usuallyoccupied bythe tissue papilla

WETTYPODONTBEFORE YOUTAKE THEIMPRESSION


59/92

B. Tray Adaptation

Trays may be heated over a bunsen burnerto soften and allow the tray to bestretched or adapted to the arch prior toadding wax to the borders. Usually it willbe required with the Mandibular tray.


60/92


61/92

C. Wax Addition to Impression Trays

After the tray has been tried in thepatients mouth and determined to

bethe correct size for this patient. Waxmay be added to extend or lengthen thesides of the tray in order to register

the muco-buccal fold and freenumattachments.


62/92

Adapt & Extend with wax when needed


63/92


64/92


65/92


66/92


67/92


68/92

Be sure to apply the adhesiveafterthe tray has been tried in

the patient and selected as theone to be used.

F l b d b f l t t


69/92

For our lab procedure, be careful not totouch the typodont with your fingers or

gloves if you have adhesive on them as it willcause the alginate to stick to the typodontand you will not be able to remove the

impression without tearing it!!

Today we will not be using the spray

unless there is a problem with thealginate pulling loose from the tray inremoving it from the typodont


70/92

X Impression Procedure


71/92

X. Impression Procedure

Separate the Maxillary & Mandibulararches of the Yypodont by removing thesprings-- be careful not to lose thesprings!!


72/92


73/92

Removalwith a

SNAPonce theJeltrateis set


74/92


75/92

Note void areain anterior


76/92

You will receive a Max.


77/92

and Mand.Tray--You mayuse them for the next

lab also.so dont throwthem away!!

You will not have to useany marginal wax asthese trays extend farenough to register theborders of the typodont


78/92

B. Model Fabrication Wrap impression in MOISTpaper towel to

avoid drying out or

Pour (using Dental Plaster) before takeMaxillary impression


79/92

A vibrator is used to decrease air bubbles and producea denser model


80/92

Alginate Clean-up


81/92

WIPE WITH A PAPER TOWEL AFTER SET THEN WASH BOWL

Plaster/Stone Clean-up


82/92

Plaster/Stone Clean upWIPE WITH A PAPER TOWEL BEFORE SET THEN WASH BOWL


83/92


84/92

POUR IMPRESSION FIRST

Note LOSS OF GLOSS


85/92

Second Pour = Base Fabrication


86/92


87/92

BE VERY CAREFUL NOT TO


88/92

Impressions may beboxed with wax inorder to pour a

one stage modelImpression must bekept upright!

BE VERY CAREFUL NOT TODISTORT THE IMPRESSIONWHEN YOU WRAP THE WAX

AROUND THE IMPRESSION

Wide masking tape may also be used


89/92

being careful not to distort the

impression during its placement.


90/92

Rubber modelformers mayalso be used--Be careful theimpression does notsink down into thePlaster!!


91/92

Happy Impression Making!!!!!!!


92/92

Happy Impression Making!!!!!!!

The

Berry

End

alginate impression material

Documents