Now we taking the impression , what kind of impression material we use?

1-elastomers 2-hydrocolloid

The reversible agar agar you can use it its very accurate . but the irreversible aliginate will not use it, only use for antagonist arch.

So the material we use are elastomer (four material you know) when handeled correctly all these materials can produce a cast with sufficient accuracy and surface details for duplication of your clinical crown

-irreversible hydrocolloid (alginate) can destroy easily, no dimensional stability so should pour immediately ,poor production of details, low tear strength mean when you get it out from pt. mouth it will tear and distort the impression so you cannot use it for crown and bridge only use it for antagonist arch.

we preserve the impression the impression by plastic bag

ال فوق الماء من قطنة نضع ال impressionال تعمل رح النهاabsorption للمحافظة الطرف على القطنة نحط فممكن للماء

ال غير .humidity e atmospherعلى ال فقط-reversible hydrocolloid agar agar components is

polysaccharide,& hydrophilic ,,,hydrocolloid are hydrophilic mean high amount of water ,,agar agar have low tear resistant same as alginate. But can produce good detail dimensionally un stable should pour immediately ,remember for hydrocolloid low tear resistance so accuracy taken when they have certain bulk , on the other hand elastomer

elastomer ال كانت اقل المادة كانت النه accuracyكلما اعلىبيصرلها so we have shrinkage polymerizationهي

Polysulfide

First material was discovered ,, we used poly sulfiude in cr&br but it has problems like Bad smell , 15 min in pt. mouth,

ال عن تحسن اجت hydrocolloidولكن

(4 elastomer , 2of 4 :dimensional unstable should pour with 1 hr ,, 2:very dimensional stable).

Good reproduction of details-

-Polymerization shrinkage(0,5-0,05%)

Pour with 1hr-

Poor elastic recovery from deformation-

فم siliconفي elastic recoveryاعلى** من شلتها لما يعنيفيها بكون .stessالمريض اول زي بترجع ثم ومن

Should be use with custom tray (metal support and control amount of material (volume)reduce amount of volume in elashomer cuz to reduce dimenshional change that will occur stay 15 min in pt. mouth

بال يتأثر الوقت .tempو mostioureهذا

It is not will tolerated because of it taste and smell-

Moderately hydrophilic-

Unpolymeralized material very sticky-

Polyester :hydrophilic ,c-silicon and a-silicon very hydrophobic*

-Not use any more

Silicon

C-silicon ,a-silicon

c-silicon (c : condensation) its condensation polymerization: condense molecule and release by product"water &ethanol" cuz dimensional instability

limited shorter working time 6-8 min-

-very much depended on amount of catalyst (increase catalyst , increase speed of reaction)

less affected by room temp and humidity not like polysulfide-

decrease in polymerization shrinkage (0.3-0.6)-

-very hydrophobic 2 clinical significance 1-keep moisture control 2-use surfactant to make the pouring easy

dimensional unstable-

must pour within 1hr-

poly sulfuide +c-silicon are dimensionally unstable because we have condensation polymerization ,by product from polysulfation +c-siloicon water +alcohol cuz evaporation once polymerization occur ,cuz dimensional contraction so its dimensional unstable but c-silicon have excellent elastic recovery.

Excellent reproduction of details-

Very good tear resistencce-

No odor-

can mix it with gloves-

But a-silicon ,his enemy is latex**

Relatively low coast-

Tube (putty)and and activator

poly ether

-Develop in 1960

Very low polymerization shrinkage (0.15%) "very low- "

Low tear resistance-

Excellent dimensional stability (pour it with 1week)-

-Stable only when keep it dry otherwise absorb moisture because polyether from elastomer,the most one hydrophilic

Very expensive ,very good material-

Good accuracy-

Short setting time (3-5)min-

-One disadvantage:stiffness ,so its rigid ,so not used with undercuts (separation or breakage will occur when there is undercut ) silicon are used instead

-Less elastic recovery than addition silicon

-Unpleasant taste but not compared with poly sulfide

-Relatively expensive

-Important property for polyether:other than hydrophilic ,, snap set :transition of polyether from plastic to elastic phase is up right in contrast to other elastomer this change occur over

long period result in change in elasticity and flowability during working time so impression inaccuracy occur

Means: polyether stay plastic for 2min then suddenly set (full working time),, silicon from the moment you start mixing ,the setting is start ,the characteristic it change ,so if you

بال تتجمد , mixطولت بدات انها more viscouse and moreتجدhard المريض بفم وضعها استطيع ال و

Note: polyether and silicon have same setting time

Span set is advantage for polyether ,addition silicon

Addition silicon

Most material ,you will use in uincs-

Most common use-

Most accurate and most dimensionally stable (with same level with polyether)-

Longer working time than c-silicon (3.5min)but have same setting time-

Low polymerization shrinkage (0.05-0.06)-

High dimensional stability you can pour after 1 week and pour more than once-

Hydrophobic ,you can apply surfactant before pour it-

Affected by temp .,increase temp ,cause decrease setting time-

-Cooling increase setting and working time by 15%(one min. and half)so we always but it in refrigerator

-Less rigid than polyether(polyether most one rigid)

- Excellent elastic recovery

- be aware from latex gloves

- No smell

- you have heavy &light body differ in viscosity (mean differ only in amount of filler)

- we have always high & low viscosity

( high viscosity work as tray "modifie your tray and turn it as custom tray "& there will be a thin space for light body (low viscosity) to give detail)

Some time come as auto mix

عن* نعوض ممكن الحاالت بعض من light and heavy bodyفيmedium body (by one phase)خالل

* Impression making: can be use with stock or custom tray

- trays (perforated, not perforated, plastic, metal, Dr.prefer metal because it's more rigid , different sizes & shapes).

- we should always apply adhesive on your tray other wise impression will get out from tray (inaccurate impression)

Custom tray is better because:

1- Reduce amount of material (silicon : 3 mm, hydrocolloid : 5 mm (bulk), elastomarse : 3mm, zn oxide : 0.5 mm

2- Reduce stress (deformation) So reduce polymerization shrinkage.

Tray requirement ---> rigid, make stopper, clearance (3 mm for elastomer) ,open for frenum, rigid handle, smooth margin.

3 type of final impression:1) 2-stage (we have heavey body & light body) also called

(putty – wash) puttyكالمعجون: wash:خفيف2) One stage I need someone to mix the heavy body while I

do light body.3) Mono phase (medium) , It's one phase also called signal

phase.* 2 – stage (putty & wash)- 2 color of some material with different viscosity (light &

heavy body)1. Select the tray inside pt. mouth.2. Apply adhesive & wait it to dry (5 min.).3. Isolate your area before taking your impression.

4. Take your first impression by heavy body (you will dispense equel amount of base & catalyst them mix them, place your material on the tray, don't over fill your material because it's viscous " if you over fill and your tray not very rigid, it will distort your tray ".

* Automixing , will always be free of bubbles 5. Seat inside pt. mouth & wait 3-5min or until fully

polymerized. (one common mistake, the student when feel the material is rigid directly he remove it from pt. mouth, rigid Not mean that it have full seating, once you remove it & put it on punch , polymerization will continue , shrinkage will continue , so impression will not be accurate , so you have to wait 5 min.

6. Create space for light body , so remove undercut from your impression (so remove inter dental tags because they will prevent light body from flow & heavy body become rigid after polymerization so it's hard to put it again pt. mouth without cuts these tags) , always your heavy body should enter passively on pt. mouth before apply the light body.

7. Use scap channels for excess light body to get out, and have thin light body

(if there is no scap channel, we will have thick light body).

Note: low viscosity have higher polymerization shrinkage because have less filler.

Note: - detials are taken from light body not from heavy body.

- In heavy body, you keep your retraction cord because heavy body will not enter in the sulcus.

- Only remove retraction cord just before you taken your light body impression.

- I remove retraction cord & put light body impression at the same time.

- We mix light body, then fill it on the syringe cause your light body is low viscosity &need to inject around finish line or light body come with gun that will mix your light body and this very thin tip ,you can inject light body all around the heavy impression ,and around your prepration on pt. mouth then do little pressure (do not do over compression because you will distort impression)then wait and remove it from pt. mouth.

*one stage (double mix )--both heavy & light body are placed in the mouth to set at

the same time.-Some body mix heavy body and put it on tray and I put

light body on the in pt. mouth and on the heavy body. - -since large material to be polymerized so use it with A-

silion & polyether (have high dimensional stability & low shrinkage ) because heavy & light body will shrink together so if material have more shrinkage the material

will be inaccurate . -2 stage we put heavy body shrinkage occur , I fill the

space by light body* -Stages: 1-tray selection

- 2 -Some body mix heavy body and put it on tray and I put light body on the in pt. mouth and on the havey

body. - 3-both heavy body and light body will set together -How to differentiate between one stage and 2stage?

-1-no under cut on 2 stage- 2 -amount of light body (blue in color)in one stage is

less because heavy body displace all the light body -*monophase

-One impression material---One viscosity (medium viscosity)"instead of heavy and

light body" -One color-

-You can have very accurate details---Exp if we have supragingivally finish line ,good finish

line ,good mostioure control ,good accessibility so we can use monophase (and we can get good details)

-29:50-29:59 I could not hear this part --Also called regular body

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-Evaluation of impression material -We should see finish line and imm intact uninterrupted

cuff of material (retraction cord)in root surface -No bubble

-No tear s-No streaks means (streaks means improper mixing)

-No separation (separation means no adhesive)-Void and bubble on finish line means improper

injection ,improper moisture control ,should be repeated-Tearing in cuff or finish line means in adequate retraction

of gingival ,inadequate material ,remove impression before setting

-Exposure for the tray (means over pressure)-Inaccurate details (inadequate retraction ,presenting of

material before long time while mixing material ,that become set and when enter pt. mouth it will not register details bubble means taken material before it set (not completely polymerized)or all oral cavity have bubble

-(mcq on final)------------------------------------------------------------------------

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-Disinfection**hypochloraite

- _very cheap

_1:10 hypochlorite

_ spray or immersion depend on material if material hydrophilic spray so (hydrocolloid spray) ,,,,,,elastomerimmersion

*wash under running water will always always eliminate more than 95 % of any germs of bacteria on impression then put in disinfect before we send it to the lab .

*Disinfection before sending to lab : we have Gluteraldehyde , iodoform sprays . Hydrophilic materials should not be soaped but sprayed in 1/10 diluted sodium hypochlorite and then stored in plastic bags for 10min The Immersion : disinfectant is used for elastomars except for POLYETHER (because it's hydrophilic), and we could use gluteraldehyde or phenolic compounds , iodoform can be used for everything except for POLYETHER.

-Ya3ni el hydrophilic materials zy el polyether lma neje n38mhm ma bnn23hm zy ma bn3ml bl lab..bnrasho rash b

iodoform spray. -exam :iodoform can use with every thing expect poly

ether ----------------------------------------------------------------

Reversible hydrocolloid "Agar agar"

Agar agar on:

-1(-100 degree:liquid (sol)-2-65 degree :gelification)

-3-mouth of pt.:temp. lower, become gel but to accelerate this process we use special tray with water coolant all around (convert the material to gel)

-We use very huge container -Not dimensionally stable (we have go directly to the lab to

pour it)thats why people do not use it -Excellent details

-2viscosities (heavy& light body)-Note:when talk about final impression on CR&BR always

remember 2 viscosity (heavy and light body )3baths (100degree ,65degree,40degree)*

40 degree is temporing bath in order not to burn the pt. when ,remove it from 65 to mouth pt. it will burn the pt .

-Note : -*Agar agar setting from outside to inside of tray because

of coolant -Elastomer setting inside to outside of tray because we

have heat inside pt. mouth*