zinc polycarboxylate.pptx

zinc polycarboxylate

1. ZINC POLYCARBOXYLATE CEMENT 2014 Dr. SV.SATISH Professor & HOD Dept of Conservative Dentistry & Endodontics Navodaya Dental College

2. Cements Substances used to glue 2 solid objects together 2014

3. In addition to the gluing function, Dental Cements own many different applications 2014

4. 2014

5. 2014 Zinc Oxide Alumino Silicate Glass Phosphoric Acid P ol y ac r yl i c Acid Eu g enol ZOE & Ca(OH) 2 Zinc Polycarboxylate Glass Ionomer Silicate Zinc Phosphate Cements set via Acid-Base Rx

6. How it sets? via acid-base Rx (Chelation) ZnO + H 2 O  Zn(OH) 2 (1) Zn(OH) 2 + E  Zinc Eugenolate (2) Presence of water is essential – Saliva could help Zinc acetate dissolves faster in water  zinc hydroxide Mixing on either paper pad or glass slab using a stainless steel spatula at high P/L ratio (4 :1) Th i n m i x  f o r t emp. c eme n t ation Th i c k m i x  f or t em p . fi l l i ng Set material Matrix of zinc eugenolate (chelate) + Dispersed non-reacted Zinc oxide particles 2014

7. 2014 ZINC POLYCARBOXYLATE CEMENT

8. Liquid 1. Powder Zinc oxide Magnesium oxide Flourides Poly-acrylic acid (30-40%) Water 2. Powder in a single bottle water settable material Freeze dried acid is blended with the powder 3. Capsules 2014 Presentation forms

9. 2014 Mixing On a glass slab using stainless steel spatula PAA is viscous and needs more effort during material’s mixing Thin mix ( P/L ratio 1.5:1)  for cementation Thick mix ( P/L ratio 2.5:1 )  for cavity base /temp. filling How it sets? Through a acid-base Rx ZnO + PAA  Zn-polyacarylate + H 2 O Set material matrix of zinc polyacrylate salt+ dispersed non-reacted zinc oxide particles

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11. 1. Biological Characteristics Pulp irritant -- fresh mix is acidic But less than zinc phosphate cement is -- Ca(OH) 2 liner is needed in deep cavities -- Thin mix is more irritant than the thick one -- Set material becomes neutral in 48 hrs Low thermal diffusivity -- insulate thermal and electrical irritations Material’s Characteristics (BMIECP ) 2. Mechanical Characteristics Its strength is comparable to that of zinc phosphate cement -- withstand amalgam’s condensation forces (cavity bases) -- could withstand masticatory forces ( permanent cementation /temp filling) 3. Interfacial Characteristics 2014 Chemically adhere -- to the tooth and base metal restorations Film thickness similar to that of zinc phosphate cement (15μm)

12. 4. Esthetic Characteristics Opaque – not used to lute translucent ceramic restorations 5. Chemical Characteristics More soluble in water than zinc phosphate cement -- thin mix dissolves more than the thick mix 6. Practicability 2014 Viscous liquid make the mixing process a little pit difficult All metallic instruments should be cleaned up while the cement still unset To achieve better bonding Tooth surface should be cleaned and dried from saliva Mixed cement should be applied to tooth structure as fresh as possible

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