Zinc oxide Eugenol-Impression Material.pptx

Prosthodontics

1. Zinc oxide Eugenol-Impression Material Discussion II

2. Content Introduction Composition Properties Types Uses Manipulation Setting reaction/setting time Advantages/Disadvantage Other eugenol pastes References

3. Introduction Zinc oxide eugenol is rigid, irreversible impression material.

4. Composition In paste form in two tubes Base (white) Zinc oxide 87% Vegetable 13% or mineral oil Catalyst (Red) Eugenol or clove oils 12% Gums or 50% Polymerized resin Filler(silica type) 20% Lanolin 3% Resinous balsam 10% Accelerator( Cacl ₂) 5% color

5. Properties Non-toxic Adherence to tissue Mucostatic or mucodisplacive Good surface detail in thin section Good dimensional stability Stable on storage and good shelf life Compressive strength – 7 MPa Hardness Type I – 0.5 mm(not greater than) Type II – 0.8 – 1.5 mm

6. Types According to the final setting time there are 2 types Initial setting for both is 5 mins Type I – Hard paste – 10 mins (Final set) Type II – Soft paste – 15 mins ( Final set)

7. Uses of Zno eugenol Impression for edentulous mouth Surgical dressing Bite registration paste Temporary filling material Root canal filling material Cementing Medium Temporary relining for denture

8. Manipulation

9. Conti.. Mixing is done on oil-impervious paste or glass slab Equal proportions of two pastes is squeezed on mixing slab (1:1 ratio) Flexible stainless steel spatula is used for mixing procedure Two strips of contrasting colors are combined in 1 st stroke

10. Conti.. Mixing is continued for appox . 1min (until homogenous color ,streaks free mixture obtain) Mixing time – 45 to 60 seconds Mixed paste is loaded in a closed fitting tray after tracing with green stick compound to give support to the paste When final set occurs the impression can be withdrawn from the mouth

11. Setting reaction ZnO +H₂O → Zn(OH)₂ Zn(OH)₂ + 2HE → ZnE ₂ + 2H₂O Setting reaction is a acid base reaction to form a chelate also k/a chelation reaction

12. Factors affecting setting time Setting time can be shortened by adding accelerators ,drop of water or extended mixing time Setting time can be prolong by use of cool spatula/slab or plasticizer such as inert oil and waxes

13. Dimensional stability Quite satisfactory Shrinkage( less than 0.1%) occurs during hardening If tray material is dimensionally stable the impression can be preserved indefinitely with out change

14. Advantages Dimensional stability Good surface detail reproduction due to low viscosity Can be added to with fresh Zinc oxide Mucostatic or Mucodisplacive Adheres well to impression compound Stable after setting

15. Disadvantages Cannot be used in very deep undercuts Only sets quickly in thin section Eugenol is allergic in some patient Variable setting time due to temperature and humidity Material is non elastic and may fracture if undercuts are present Messiness

16. Disinfection 2% Glutaraldehyde solution for 10 mins immersion then rinse and pour

17. Other eugenol pastes Non eugenol paste To overcome disadvantages of being stinging or causing burning sensation , allergic caused by eugenol non eugenol paste is introduced Instead of eugenol orthoethoxybenzoic acid (OBA) is added Reaction not affected by temperature or humidity Bactericidal agents or other medicaments can be added

18. Surgical paste Used after gingivectomy for retention of medicaments and promote healing These are generally softer and slower in setting rxn Mixture should be capable of being packed as rope into wounds Should be strong enough to resist displacement

19. Bite Registration paste Used for recording occlusal relationships ZoE paste allows almost no resistance to closing of mandible ,thus allowing more accurate inter occlusal relationship records to be formed Records more stable than waxes Setting time is shorter to prevent distortion

20. References Applied Dental Materials - 9 th edition- Jhon F.McCabe and Angus W.G.Walls Restorative Dental Material – Craige Phillips’ Science of Dental Materials 11 th edition - Knneth J Anusavice Dental Material Science, Mannippalli Dental Materials and Their Selection, 3 rd edition, William J O’Brein Clinical Aspects of Dental Materials ,Marcia Gladwin Micheal Bagby 3 rd edition

21. Thank you