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Recent Advances In Impression Materials

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by

Tarek Anwar

on 11 December 2012

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Transcript of Recent Advances In Impression Materials

Recent Advances In Impression Materials and Techniques Non-Elastic Elastic Classification Of Impression Materials Impression Plaster
Impression Compound
Zinc Oxide & Eugenol
Wax Advantages: Good Surface detail
Excellent dimensional stability Disadvantages: Fractures in undercuts
Taste & roughness cause vomitting
Exothermic reaction Uses: Labial & occlusal soldering index Uses: Advantages: Non-irritant & non-toxic
Reheated, readapted
Mucocompressive
Good shelf life Disadvantages: Poor dimensional stability
Poor surface detail
Distortion upon removal form undercuts
Uses: Interocclusal recording with bite frame Advantages: Dimensional stable
Good surface detail
Good shelf life Disadvantages: No use in deep undercuts
Sets quicker in thin sections
Eugenol allergy Uses: Wax pattern, bridge soldering & bite registration Advantages: Ease of manipulation
Cheap Disadvantages: Deformation on removal from undercut
Easily distorted Hydrocolloids Elastomers Reversible (Agar Agar): Irreversible (Alginate): Uses: Reused as a duplicating material Advantages: Not hydrophobic, good model surface
No custom tray required
Good elastic properties
Inexpensive
Excellent shelf-life Disadvantages: Expensive equipment required
Must be poured immediately
Weak in deep sulcus (needs bulk) synersis & imbibition Uses: Primary impressions in dental work Advantanges: Ease of mixing & manipulation
Good surface detail (less than agar)
Pleasant taste & odor, patient comforting
Easily removed from undercuts Disadvantages: Poor dimensional stability
Poor tear strength in thin sections Polysulfides


Condensation Silicone


Addition Silicone


Polyether Advantages: Excellent strength in deep sulcus
Poured more than once
Electroplated
Pouring can be delayed for 1 hour
Adequate shelf life (1 year) Disadvantages: Custom tray required
Hydrophobic
Heat & humidity sensitive
Undercuts should be blocked out
Foul odor
Stains clothes Advantages: No custom tray
Moderate strength in deep sulcus
Finish line easily read
Pleasant odor & appearace
Adequate shelf life (1 year) Disadvantages: Poured shortly after removal
Hydrophobic
Difficult electroplating
Easily distorted Release of by-product: methyl group Advantages: Superior dimensional stability
Delayed pouring
Poured more than once
Pleasant odor & appearance
Superior electroplating
Good shelf life (1-2 years)
No custom tray Disadvantages: Extremely hydrophobic
Special care in pouring
Most expensive Hydrogen gas
Latex gloves
Advantages: Fast setting
Finish line easily read
Superior dimensional stability
Can be poured more than once
Pouring can be delayed
Good shelf life (2 years)
Hydrophilic Disadvantages: Custom trays required
Very stiff (undercuts should be blocked out)
Short working time ???
Expensive Vinyl Polyether: Combination of 2 materials
Supplied in 4 different viscosities
No bitter taste of polyether
Spearmint flavor
Powedered gloves contamination Impression Techniques 1 step:



2 step 1 phase
2 phases Impression Technique in Implants Types of Tissue Management: Mechanical



Chemical



Surgical

Optical Impressions Types of CAD/CAM systems: Aquistion only



Scan and mill CEREC


E4D


iTero


Lava Milling Machines Clinical Outcomes References: http://www.dentistry.bham.ac.uk/cal/impress/intromat.html

http://www.dentalaegis.com/id/2005/10/impression-material-basics

http://www.prodentalcpd.com/members/articles/restorative/restorative/a_guideline_for_excellent_impressions_in_theory_and_practice

Schillinburg, Fundementals of Fixed Prosthodontics

Craigs, Restorative Dental Materials
Question 1:
List the disadvantages of Polysulfide impression materials Question 2: Justify the use of surfactant in some impression materials and state its clinical significance THANK YOU
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