ZINC OXIDE EUGENOL CEMENTS PRESENTation endo

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1. ZINC OXIDE EUGENOL CEMENT

2. CONTENTS Introduction Composition Setting reaction Clinical applications Available systems Types

3. Manipulation Properties Advantages Disadvantages Modifications of ZOE cement Noneugenol cements

4. INTRODUCTION ZOE cement - ADA Specification No. 30 I ntroduced in 1858 as a cement that was very easy to handle and manipulate even in the presence of moisture and well tolerated by the pulp.

5. COMPOSITION POWDER Zinc oxide: 69% Rosin: 29% (to reduce brittleness) Zinc acetate: 0.7% (accelerator) Zinc stearate: 1% (plasticizer) LIQUID E ugenol - chemical essence of oil of cloves, weak acid, phenol derivative, obtundent Some olive oil – plasticizer

6. SETTING REACTION Zinc oxide reacts with eugenol to form zinc eugenolate . In this chelation reaction, two molecules of eugenol (HE) react with ZnO to form eugenolate ( ZnE 2 ). Water acts as an accelerator. The autocatalytic reaction can be presented as: ZnO + H 2 O → Zn(OH) 2 Zn(OH) 2 + 2HE → ZnE 2 + 2 H 2 O ( Base) (Acid) (Salt)

7. CLINICAL APPLICATIONS 1. As long-term and short-term luting agents 2. As temporary and intermediate restorations 3. As root canal sealers, e.g., Grossman’s or Ricket’s sealers 4. Surgical packs 5. Impression pastes

8. AVAILABLE SYSTEMS Commercially available as powder/liquid or pastes (two tubes or single container). Some commercially available ZOE cements include Tempbond (Kerr) and TempoSIL ( Coltene / Whaledent ).

9. TYPES Type I: For temporary cementation Class 1: Powder–liquid Class 2a: Paste–paste (eugenol) Class 2b: Paste–paste ( noneugenol ) Class 3: Paste–paste ( nonsetting ) Type II: For long-term cementation Class 1: Powder–liquid, e.g., Super EBA, intermediate restorative material (IRM)

10. Type III: Temporary filling materials and bases Class 1: Powder–liquid Class 2: Paste– paste Type IV: Cavity liners Class 1: Powder–liquid Class 2: Paste– paste

11. MANIPULATION POWDER LIQUID TYPE Powder is measured and dispensed with a scoop. The liquid is dispensed as drops. A glass slab and cement spatula are used for mixing. The mixing process first incorporates large increments and then smaller increments until the desired consistency is obtained.

12. LUTING CONSISTENCY The cement pulls out into a string when the flat surface of the spatula is raised from the mixed material. ADA specification states that the film thickness for ZOE temporary cements should be no more than 40 μ m , while for permanent cementation it should be less than 25 μ m .

13. TEMPORARY RESTORATION CONSISTENCY The mixing is done with a high P/L ratio until the mix attains the consistency of a dough that can be rolled into a rope . If too little powder is used, then the mix becomes sticky. If too much powder is used, the mix becomes crumbly.

14. PASTE FORM T wo-paste system Dispense equal amounts of both pastes (accelerator and base) on the glass slab. M ixing is done till a uniform color is obtained.

15. MANIPULATION FOR SURGICAL PACK A thin consistency is mixed with a few cotton fibers to increase strength and durability. Tannic acid is added to act as hemostatic agent and chlorhexidine to provide the antibacterial action. P laced on the surgical site postoperatively, which relieves pain and provides comfort to the patient. These have a greater quantity of vegetable oil to improve plasticity and aromatic oils to improve the taste.

16. PROPERTIES 1. Solubility: Eugenol can leach out from material leading to hydrolysis and disintegration of the cement. Hence, these cements are mainly for temporary usage . 2. Thermal: The coeffi cient of thermal expansion is close to that of the tooth, which explains its good sealing ability and minimal microleakage . ZOE is a good thermal insulator .

17. 3. Strength : The compressive strength is lesser than zinc phosphates though reinforced variations of ZOE can withstand amalgam condensation. The long-term cements used for luting are not strong as compared to other luting cements The short-term luting cements are weaker which is a desirable feature for temporary crowns needing removal. 4. Biocompatibility : ZOE acts as an obtundent due to the presence of eugenol, with a sedative effect on the pulp. Its neutral pH accounts for the mild response on the pulp.

18. However, in higher concentrations, the eugenol can be toxic; hence, it should not be directly used on the pulp. 5. Optical properties : ZOE cement is opaque and white in color. 6. Adhesion : Though it does not have chemical adhesion to enamel and dentin, ZOE provides an excellent seal at the tooth–restorative interface . The lower the P/L ratio, the better is the seal.

19. ADVANTAGES ZOE is least irritating to the pulp - obtundent effect of eugenol and the neutral pH of the initial mix. It also has an anodyne or soothing effect on the inflamed pulp. E xcellent thermal insulation when used as base Easy to remove and clean when used for temporary cementation of provisional crowns.

20. DISADVANTAGES D oes not adhere well to enamel and dentin - causes microleakage and cannot be used for interim and long-term restorations. L ow strength and high solubility , it cannot be used for permanent cementation. S olubility is highest among all cements.

21. MODIFICATIONS OF ZOE CEMENT 1. Polymer-reinforced ZOE The powder is modified with the addition of resins/hydrogenated rosin and the liquid has polystyrene or methylmethacrylate added to it. The compressive strength is increased – can be used as an intermediate restoration for 3–6 months. L ess soluble in the oral fluids.

22. 2. Ethoxybenzoic acid (EBA) modified ZOE (Super EBA) Powder Zinc oxide: 60%–75% Alumina: 20%–35% Hydrogenated rosin: 6% Liquid Eugenol: 37% Ethoxybenzoic acid (EBA): 63% The EBA encourages the formation of a crystalline structure and thereby improves strength considerably.

23. NONEUGENOL CEMENTS Developed to be used for interim luting purposes in clinical cases which are to receive resinous restorations. Instead of eugenol, carboxylic acids and other chemicals are used to react with zinc oxide. They are not brittle and excess is difficult to remove.

24. Uses: Used to lute temporary crowns , when a resin cement has to be used to lute the final restoration. It can also be used for patients who are allergic to eugenol .

25. REFERENCES S.Mahalaxmi . Direct restorative materials: Dental cements. Materials Used in Dentistry,2 nd edition . New Delhi : Wolters Kluwer Health. 2018;247-251.