Zinc Polycarboxylate & Glass Ionomer Cements PDF

Dental Cements (2) Dr. Mohamed Mahmoud Abdul-Monem Assistant Professor of Dental Biomaterials AIU Fall 2024  Zinc polycarboxylate cement Zinc polycarboxylate cement First cement that developed an...

Dental Cements (2) Dr. Mohamed Mahmoud Abdul-Monem Assistant Professor of Dental Biomaterials AIU Fall 2024  Zinc polycarboxylate cement Zinc polycarboxylate cement First cement that developed an adhesive bond to tooth structure. Dr. Mohamed Mahmoud Abdul-Monem 3 Uses Luting cement Base & Liner Dr. Mohamed Mahmoud Abdul-Monem 4 Cementation of orthodontic bands Temporary filling Composition Powder Liquid 1. Zinc oxide  Polyacrylic acid aqueous solution (30-40 %) 2. Magnesium oxide  Itaconic acid (To prevent gelation 3. Bismuth oxide upon storage) 4. Aluminum oxide  Tartaric acid ( To control setting 5. Stannous fluoride (to increase reaction) strength & imparts limited anti-  Sodium hydroxide ( To control pH cariogenic properties) and liquid viscosity)  Water Dr. Mohamed Mahmoud Abdul-Monem 5 Setting reaction Zinc oxide + Polyacrylic acid Zinc polyacrylate gel + unreacted ZnO The set cement is a cored structure of amorphous zinc polyacrylate gel matrix in which unreacted Zinc oxide powder is dispersed. Dr. Mohamed Mahmoud Abdul-Monem 6 Manipulation  Mixing over small area ( Not to destroy the formed gel.  Reaction isn’t exothermic.  Use when glossy ( Indicating free carboxylic groups for better bonding with tooth structure).  Shear stress during mixing to decrease viscosity (Shear-thinning properties)i.e.,(Pseudoplastic). Dr. Mohamed Mahmoud Abdul-Monem 7 Retention  Chemical bond (Ionic bond) with tooth structure.  Bonds to enamel more than dentine because of the higher calcium content of enamel.  Bonds to oxide layer of base metal alloys and stainless steel. Dr. Mohamed Mahmoud Abdul-Monem 8 Biocompatibility Biocompatible in comparison to zinc phosphate, due to : 1. Higher pH. 2. Larger size of polyacrylic acid molecules that can’t pass through dentinal tubules. 3. Ionic bonding to tooth structure. Dr. Mohamed Mahmoud Abdul-Monem 9 Zinc polycarboxylate Advantages Disadvantages 1. Biocompatible (non irritant). 1. Lower compressive strength (In comparison to zinc phosphate). 2. Chemical bond to tooth. 2. Technique sensitive (Needs to be 3. Low solubility. used when glossy to ensure 4. High tensile strength (Not brittle). maximum bond between carboxylic groups and calcium of tooth structure). 3. High viscosity (Thus shear stress is applied during mixing, to ensure complete seating of restorations). 4. Passes through a rubbery stage during setting , so care is needed during removal of excess cement to prevent pulling of cement from beneath the restoration leaving a Dr. Mohamed Mahmoud Abdul-Monem void. 10  Glass ionomer cements (GICs) Dr. Mohamed Mahmoud Abdul-Monem 11 GICs Adhesion Biocompatibility Anti-Carigoenic Dr. Mohamed Mahmoud Abdul-Monem 12  Presentation form Dr. Mohamed Mahmoud Abdul-Monem 13  Capsule Mechanical Capsule applicator activator mixer Advantages: GIC capsules 1. Homogenous mix. 2. Correct P/L. 3. Less waste. Dr. Mohamed Mahmoud Abdul-Monem 4. Ease of application. 14 Types and Type I : Type II: Type III: Uses of GIC Luting cement Restorative (Class III & V) Liner and Base What is the difference ? Dr. Mohamed Mahmoud Abdul-Monem 15 Composition Powder Liquid (Ion-leachable glass)  Silica  Polyacrylic acid aqueous solution.  Alumina  Itaconic acid (Reduces viscosity and inhibits gelation upon storage)  Calcium fluoride  Tartaric acid (Accelerator)  Sodium fluoride  Water Calcium aluminosilicate glass + Fluoride salts Dr. Mohamed Mahmoud Abdul-Monem 16 Setting reaction of GIC 1.Dissolution Powder attack by acid. (Acid-Base reaction) Ca, Al, Na, F salts are leached into he aqueous polyacrylic acid. 2.Gelation Ca reacts with carboxylic groups and form calcium polycarboxylate salt gel. (Crosslinking) Al reacts with carboxylic groups and form aluminum polycarboxylate salt gel. (Crosslinking) Silica gel is formed around the degraded particles. Na and F Combine to form fluoride salts. (Anticariogenic) 3.Hydration Dr. Mohamed Mahmoud Abdul-Monem Matrix and silica gel are hydrated and strength is developed. 17 Structure of set cement The set cement consists of unreacted alumino- silicate glass particles surrounded by silica gel held by an amorphous matrix of cross-linked hydrated Ca and Al polyacrylate salts. Dr. Mohamed Mahmoud Abdul-Monem 18  Bonding of GIC to tooth structure Dr. Mohamed Mahmoud Abdul-Monem 19 GIC Advantages Disadvantages 1. Long-term fluoride release 1. Technique sensitive ,sensitive to (Anticariogenic properties) water contamination and dehydration. (Needs varnish 2. Adhesion to tooth structure. coating after application) 3. Biocompatibility. 2. Low abrasion resistance. 4. High compressive strength. 3. Brittle (Low tensile strength). 4. Soluble in saliva. Dr. Mohamed Mahmoud Abdul-Monem 20  Modifications of GIC Metal-reinforced GIC 1.Silver alloy admix Mix silver amalgam alloy powder with GIC cement powder before mixing it with the liquid. (By Operator) 2. Cermet Cement Sintering silver particles with glass powder during manufacturing. Resin-modified GIC Dual cure GIC Acid-Base reaction of GIC + 21 Light-cured resin Dr. Mohamed Mahmoud Abdul-Monem Uses of Modified GIC Metal-reinforced Resin-modified 1.Core-build up. 1. Direct restoration (Class III and V). 2. Base or Liner (Under dental composites). 2.Posterior filling for deciduous teeth. Dr. Mohamed Mahmoud Abdul-Monem 22 Modifications of GIC Metal-reinforced GIC Resin-modified GIC  Advantages:  Advantages: 1. Increased mechanical properties. 1. Increased mechanical properties. 2. Decreased solubility. 2. Decreased solubility. 3. Controlled working and setting time (Light-cured).  Disadvantages: 4. Increased esthetics 1. Decreased fluoride release 5. Increased bonding to tooth. 2. Decreased bonding to tooth 3. Decreased esthetics.  Disadvantages: Dr. Mohamed Mahmoud Abdul-Monem Decreased fluoride release 23  Packable GIC Flowable GIC Recent Nano-bioceramic GIC Advances in Giomers GICs Fiber-reinforced GIC Zirconia-reinforced GIC (White amalgam) Compomers Dr. Mohamed Mahmoud Abdul-Monem 24 Thank you Dr. Mohamed Mahmoud Abdul-Monem 25