Elastomeric impression materials Prof Dr Manal A Elebiary

Elastomeric impression materials Prof. Dr. Manal A. Elebiary

Prof. Dr. Manal A. El Ebiary Dental Bio-Materials Department Faculty of Dentistry Tanta & MUST Universities Elastomeric impression materials Prof. Dr. Manal A. Elebiary

How do you contact with me ? manalahmed 727@yahoo. com Elastomeric impression materials Prof. Dr. Manal A. Elebiary

Elastomeric impression materials Prof. Dr. Manal A. Elebiary

Elastomers l Consists of long chain molecules that are coiled l The materials are easy to deform and the deformation is largely reversible Elastomeric impression materials Prof. Dr. Manal A. Elebiary

Polysulfide Condensation Silicone Addition silicone Polyether Elastomeric impression materials Prof. Dr. Manal A. Elebiary

Point of Polysulphide comparison rubbers 1) Form of supply Silicon Polyether rubbers Supplied as two pastes system Light Regular heavy Elastomeric impression materials Prof. Dr. Manal A. Elebiary Light Regular Heavy Putty Light Regular heavy

Generally l Greater dimensional stability than hydrocolloid l Can be electroplated except polyether l It is preferable to cast within the first hour after removal from the mouth l Available in different viscosities according to the molecular weight and amount of fillers l Used in as impression in case of inlays crowns, bridges Elastomeric impression materials Prof. Dr. Manal A. Elebiary

Polysulphide rubbers 2) Application Silicon Whole edentulous jaw Quadrant impression Single impression Elastomeric impression materials Prof. Dr. Manal A. Elebiary Polyether rubbers Quadrant impression Single impression

Polysulfide Mercaptan Elastomeric impression materials Prof. Dr. Manal A. Elebiary

Elastomeric impression materials Prof. Dr. Manal A. Elebiary

Composition Base Catalyst Polysulfied with terminal and pendant (SH ) l Lead dioxide for polymerization l Filler as titanium dioxide and crosslinking ( 12 : 50%) oxidation of SH group = provide strength l = control consistency l Elastomeric impression materials Prof. Dr. Manal A. Elebiary Plasticizer

Setting reaction Condensation polymerization reaction Polysulfide + Lead dioxide Polysulfide rubber + water + lead oxide +H Elastomeric impression materials Prof. Dr. Manal A. Elebiary

Elastomeric impression materials Prof. Dr. Manal A. Elebiary

Properties Elastomeric impression materials Prof. Dr. Manal A. Elebiary

Accuracy l High flow l Polymerization shrinkage = 0. 25 % at the first 24 H l There is water as by-product l It should cast within one hour l Elasticity: - viscoelastic material , elastic recovery = 98% l The most flexible of all rubber materials l Compatible with die materials and surfactant improve surface wettability Elastomeric impression materials Prof. Dr. Manal A. Elebiary

Condensation Silicone Accelerator Base l l Polydimethl- siloxane with OH (hydroxyl group) l (Paste or liquid) l Tin octate Filler Elastomeric impression materials Prof. Dr. Manal A. Elebiary

Elastomeric impression materials Prof. Dr. Manal A. Elebiary

Setting reaction l Condensation l With polymerization reaction formation of Alcohol as by product Elastomeric impression materials Prof. Dr. Manal A. Elebiary

Addition Silicone Base Accelerator l Polymer with silane l Polymer with Vinyl group l Filler l Chloroplatinic acid l Filler Elastomeric impression materials Prof. Dr. Manal A. Elebiary

Setting reaction Elastomeric impression materials Prof. Dr. Manal A. Elebiary

Elastomeric impression materials Prof. Dr. Manal A. Elebiary

Accuracy Condensation l l l l High flow Shrinkage = 0. 6% Presence of alcohol as by- product More ideally elastic than polysulfide Rapid elastic recovery = 99. 5% Less flexible than polysulfide but less than polyether l l l l Addition High flow Shrinkage =. 05% No by- product More ideally elastic than polysulfide Rapid elastic recovery = 99. 5% Less flexible than polysulfide but less than polyether Elastomeric impression materials Prof. Dr. Manal A. Elebiary

Compatibility with die materials l Most materials compatible with die material l While addition silicone may produce hydrogen gas during setting it can be eliminated by addition of absorber in its composition to improve wettability Elastomeric impression materials Prof. Dr. Manal A. Elebiary

Elastomeric impression materials Prof. Dr. Manal A. Elebiary

l Addition of surfactant to facilitate casting because it is hydrophobic materials l Tear strength : - less than polysulfide and polyether l Can be disinfected l Can be electroplated Elastomeric impression materials Prof. Dr. Manal A. Elebiary

Disadvantage of addition (vinyl silicone) l It is hydrophobic materials this decrease the ability of the material to wet the soft tissue and at the same time decease the wetting of soft die materials then addition of surfactant is necessary l Sulfur contamination from latex gloves inhibit polymerization reaction of addition silicone Elastomeric impression materials Prof. Dr. Manal A. Elebiary

Polyether Base Accelerator l Polyether with ethylene imine ring group l Aromatic sulfonic ester l Filler Elastomeric impression materials Prof. Dr. Manal A. Elebiary

l Setting reaction : - addition polymerization reaction Elastomeric impression materials Prof. Dr. Manal A. Elebiary

Accuracy l High flow l Polymerization shrinkage = 0. 25 % at the first 24 H l Elasticity: - viscoelastic material , elastic recovery = 98. 9% l The Least flexible of all rubber materials l Compatible with die materials and producing excellent surface Elastomeric impression materials Prof. Dr. Manal A. Elebiary

l Tear resistance : - better than silicone but less than polysulfide l Disinfection : - dimensional change if immersion time longer than 10 minutes because hydrophilic nature l Cannot electroplated because hydrophilic nature comparison Elastomeric impression materials Prof. Dr. Manal A. Elebiary

General factor affecting accuracy l Record fine details l Small contraction due to polymerization shrinkage and cooling from mouth temp. to room temp. l Sufficient undercuts elastic to be withdrawn from Elastomeric impression materials Prof. Dr. Manal A. Elebiary

l Less likely to tear than alginate l An adhesive should be used to assure adherence of the imp. Materials with the acrylic tray. l Silver electroplated except polyether because it is a hydrophilic materials Elastomeric impression materials Prof. Dr. Manal A. Elebiary

Thickness l Hydrocolloid l Rubber = 4: 6 mm base = 2: 3 mm l Polyether = not less than 4 mm to facilitate removal because its low flexibility Elastomeric impression materials Prof. Dr. Manal A. Elebiary

Comparison Elastomeric impression materials Prof. Dr. Manal A. Elebiary

Impress. materials Monomer Reactive group Catalyst (accelerator) Polysulfide Mercaptan Lead dioxide (-SH-) Conden. Dimethyl Hydroxyl Stannous silicone silioxane (OH) octoate or Tin octoate Addition silicone Polyether Vinyl group Chloroplatin Siloxane CH 2 = CH ic acid polyether Ethylene Aromatic imine ring sulfonic ester Elastomeric impression materials Prof. Dr. Manal A. Elebiary

Elastomeric impression materials Prof. Dr. Manal A. Elebiary

Viscosity Polysulfide Condensation Additio polyether silicone n silicon Light- regular –heavy - regular + regularputty diluent heavy Form 2 pastes or one paste + liquid Odor , taste Cost Bad odor Pleasant Low cost Expensive Clean up Difficult Elastomeric impression materials Prof. Dr. Manal A. Elebiary 2 pastes Easy Better taste

Setting time Kind of reaction By product Long time = 10 minutes Moderate condensat. Addition (Ionic ) water + Pb. O Ethyl alcohol Tear resistance Model surface Hydrogen Short Addition ( ring opening) ----- Adequate Smooth Pitting of stone surface Elastomeric impression materials Prof. Dr. Manal A. Elebiary Smoo th

Biological effect Bio-compatible Dimensiona l change 0. 25 % Elastic recovery 98% Flexibility, stiffness 0. 6 % 0. 05 % 99. 5% High less flexibility Less flexibility, than flexibilit easy polysulfide y than removed polysulif from under de cut Elastomeric impression materials Prof. Dr. Manal A. Elebiary hypersensitivity, contact dermatitis, and gingivitis. 0. 25 % 98. 9% Less flexible than all rubber imp. and difficult in removal from undercut.

Water absorption Shelf life Electroplating water absorption Not absorb water Good Silver plated Limited due to deteriorati on of liquid accelerator Silver plated Elastomeric impression materials Prof. Dr. Manal A. Elebiary Hydrophilic, water sorption Good Silver plated -----

Elastomeric impression materials Prof. Dr. Manal A. Elebiary