Glass-Ionomer Restorative Materials (glass polyalkenoate cements)

Glass-ionomer family of materials: glass-ionomer cements resin-modified glass-ionomer cement polyacid-modified resin composites Note: these are not really a glass-ionomers; there is no ionic reaction

Glass-ionomer restorative materials Alfa-Fil (DMG) Chemfil Superior (Dentsply) GC Fuji IX GP (GC America) Ketac Molar (ESPE)

Glass-ionomer cements - development Wilson-Kent (72) – chemistry McClean-Wilson (74) – clinical

Glass-ionomer Restorative: hand-mixed powder – liquid products: Acid – soluble glass PAA etc in water protective varnish

Glass-ionomer cements – initial formulations acid-soluble glass polyacrylic acid (~ 50 vol. %) dissolved in water

C O C O C O C O C O C O H O H O H O H O H O H O polyacrylic acid

C O C O O H O carboxyl group carboxylate ion

Glass-ionomer cements - powder Aluminum ions make the glass soluble in acids.

Glass-ionomer cements – after 1980 acid-soluble glass polyacrylic acid or other polyalkenoate acid (~ 50 vol. %) dissolved in water

O H O H O H O H O H O H O H C O C O C O C O C O C O C O C O C O C O C polymaleic acid The number of carboxyl group is double that of PAA. Does not seem to improve the cement.

Glass-ionomer cements – after 1980 acid-soluble glass polyacrylic acid or other polyalkenoate acid (~ 50 vol. %) dissolved in water 10% tartaric acid

O O H H O H O C C C C O H H O H tartaric acid

with tartaric acid w.o. tartaric acid viscosity time

Glass-ionomer cements - structure of set cement hydrogel matrix Partially dissolved glass particle

Glass-ionomer cements - setting reaction Key concepts: polyacids are soluble in water polysalts are insoluble in water

Glass-ionomer cements - setting reaction Dissolution acid attacks glass Ca++, complex aluminum ions, & F- released by glass Ions initially dissolve into the water + polyacid solution

Glass-ionomer cements - setting reaction Gelation - 1 ions react with polyacid Ca++ react first with COO- aluminum complexes breakdown to Al+++ Al+++ react later with COO- form Ca - polysalt & Al - polysalt

Glass-ionomer cements - setting reaction Gelation - 2 form Ca - polysalt & Al - polysalt polysalts are not soluble in water long polysalt molecules precipitate matrix is a hydrogel

Glass-ionomer cements - setting reaction Hydrogel a tangle of thousands of long polysalt molecules that have precipitated water is trapped within and between these molecules

Glass-ionomer cements - structure of set cement hydrogel matrix Partially dissolved glass particle

Glass-ionomer restorative materials – Uses In general: restoration under low stress Restoration of cervical lesions (Cl. 5) – smaller lesions especially Interproximal anterior restoration (Cl. 3) Small Cl. 1 restorations in deciduous teeth Bases under resin composite restoration, especially where recurrent caries is a concern (“sandwich” technique)

+ calcium aluminosilicate glass Ca, Al polysalt hydrogel CH 2 COOH + Polyacrylic acid (PAA) calcium aluminosilicate glass CH 2 COO OOC F Ca 2+ Al 3+ Ca, Al polysalt hydrogel

G-I Technique - medium - large Class 5 Preparation - 1 maintain dry field noncarious lesions: no prep needed carious lesions: remove only caries do not bevel enamel margins

G-I Technique - medium - large Class 5 Preparation - 2: hydrate dentin place wet cotton pellet on the preparation while mixing the cement do not allow contamination by saliva or crevicular fluid remove wet cotton pellet blot prep dry with a dry cotton pellet

G-I Technique - medium - large Class 5 Initial finishing use preformed cervical matrix if possible coat surface with light-cured resin or a water-resistant varnish remove excess cement with a sharp blade or carbide bur reapply resin or varnish - light cure the resin

G-I Technique - medium - large Class 5 final finishing Delay finishing 24 hrs for best esthetics and hardest surface surfaces can be finished after 15 minutes reapply the resin or varnish - light cure the resin

Glass-ionomer restoratives - advantages fluoride release low bond strength to enamel & dentin low solubility after complete set thermal expansion like that of enamel & dentin biocompatible

Glass-ionomer restoratives - disadvantages high initial solubility subject to dehydration finishing must be delayed most are radiolucent weak subject to wear & erosion poor esthetics

Glass-ionomer Cermets

Glass - ionomer cermets - definition Cermet - A composite consisting of a combination of ceramic and metallic materials.

Cermets – Ketac Silver: Powder: glass particles sintered to 40 wt. % of 3.5 m silver particles Liquid: 37 wt% of 1:1 copolymer of acrylic and maleic acids 9% tartaric acid 54 wt.% water

Cermets – Ketac Silver - properties silver in the powder working time final set compressive strength diametral tensile str. flexural strength 40 wt.% 1.5 min 5.0 min 190 MPa (24 hr.) 14 MPa (24 hr) 32 MPa (24 hr)

Cermets – Ketac Silver – toothbrush wear amalgam microfilled resin comp. resin composite glass-ionomer restor. cermet 0.2 mm3 0.4 mm3 6.0 mm3 0.3 mm3

Resin-Modified Glass-Ionomer Cements

Resin-modified glass-ionomer restorative materials 3M Vitremer Tri-cure Core Buildup / Restorative (3M / Espe) Photo-fil Quick (3M / ESPE) Fuji Filling LC (GC America) Ketac Nano (3M / Espe)

Resin-modified glass-ionomer bonded-base materials 3M Vitrebond Light Cure Glass Ionomer Liner/Base (3M Dental Products) Fuji Bond LC (GC America) Viva Glass Liner (Vivadent)

Conventional glass-ionomer Conventional Resin-composite Polyacid-modified resin composite Resin-modified GI

Conventional glass-ionomer Conventional Resin-composite Polyacid-modified resin composite Resin-modified GI The consensus is that these are composites NOT ionomers! Ketac-Fil Dyract Compoglass Fuji Filling LC Vitremer Ketac Nano

Resin-modified G-Is: liquid composition simple systems Polyacid - PAA, polymaleic, etc. polyHEMA water light cured activation system

Resin-modified G-Is: liquid composition more complicated systems Polyacid modified with methacrylate groups replacing some (-COOH) groups HEMA or polyHEMA water light-cured activation system

PAA with methacrylate graft O C O C O C O C O C O O H O H O H O H O H O R C C H 2 C H 3 PAA with methacrylate graft

O O _ _ M O C C O O O _ _ O C C O O H H O C R C H C C H C R C C H H H setting due to precipitation of metallic polysalt O O _ _ +2 M O C C O O O _ _ O C C O O H H O C R C H C C H C R C C H H H C H 3 3 Cross-link formed by addition polymerization

Resin-modified G-Is: liquid composition more complicated systems Polyacid modified with methacrylate groups replacing some (-COOH) groups HEMA or polyHEMA water light-cured activation system

hydroxyethylmethacrylate hydrophobic methacrylate group C O H 3 HEMA hydroxyethylmethacrylate hydrophilic hydroxyl group

polyHEMA (poly) hydroxyethylmethacrylate O C H . . . .

glass-ionomer lining cement: Application: Lining composite or amalgam restoration when the preparation is close to the pulp. Temporary restorations

glass-ionomer lining cement: current product: GC Fuji Lining LC GC America

glass-ionomer lining cement: Shake bottle to fluff up powder level scoop against edge of the half-diaphragm at mouth of bottle.

glass-ionomer lining cement: Glass powder – contains fluoride Liquid polymeric acid

glass-ionomer lining cement: Mixing: One scoop powder + one drop liquid Divide powder into two parts Add ½ powder to liquid – mix 5 – 10 s Add remaining powder complete mix in 10 -15 s

Direct Restorative materials - setting shrinkage

Fluoride release over time (mean of 4 Gis) From Fortsen, Biomaterials 1998;19:503-508.

Fluoride release - restorative materials

Flexural strength - restorative materials

Elastic modulus - restorative materials

RMGI restorative materials – Uses* In general: restoration under low stress Restoration of cervical lesions (Cl. 5) – larger lesions than GI restorative materials Interproximal anterior restoration (Cl. 3) Small Cl. 1 restorations in deciduous teeth Bases under resin composite restoration, especially where recurrent caries is a concern (“sandwich” technique) Notice that these uses are not too different from those for GI restorative materials.

Resin-modified glass-ionomer restorative materials – sandwich restorations

RMGI restorative materials – Class V Survival After five years more RMGI than GI Class V restorations are surviving in non-carious lesions: % Failed Time since Placement (months) amal GI RMGI Comp RC Flowable GI – 60% RMGI – 85% Stewardson et al. Brit Dent J 2012 212 (9) 1-9.

RMGI restorative materials – Class V Survival After five years, more RMGI than GI Class V restorations are surviving in carious lesions: % Failed Time since Placement (months) amal GI RMGI Comp RC Flowable GI – 44% RMGI – 78% Stewardson et al. Brit Dent J 2012 212 (9) 1-9.

Resin-modified GIs: advantages Immediate cure with visible light fluoride release stronger than GIs moderate bond to enamel & dentin low solubility immediately fewer steps that GIs; less technique sensitive

Resin-modified GIs: disadvantages polymerization shrinkage stronger, but still weaker than RCs subject to wear & erosion bond to dentin better, but still lower than DBSs poor esthetics less biocompatible than GIs

Polyacid - Modified Resin Composites

Conventional glass-ionomer Conventional Resin-composite Polyacid-modified resin composite Resin-modified GI

Conventional glass-ionomer Conventional Resin-composite Polyacid-modified resin composite Resin-modified GI Ketac-Fil Dyract Compoglass Fuji Filling LC Vitremer Ketac Nano

Polyacid-modified Resin Composites Restorative materials 3M F-2000 Compomer Restor Syst (3M) Compoglass F (Vivadent) Compoglass Flow (Vivadent) Dyract (Dentsply/Caulk) Dyract AP (Dentsply/Caulk) Dyract Flow (Dentsply/Caulk)

Polyacid-modified Resin Composites Restorative materials elan Compomer Restorative System (Kerr) Hytac Aplitip (ESPE)

TCB oligomer - Dyract (Caulk) H O O C H 3 3 C C H C C C O H C H C O O C H C H O C C C H 2 2 2 2 2 2 H C C H 2 2 C H C H 2 2 O O C C O H O H TCB oligomer - Dyract (Caulk)

Fluoride release - restorative materials

Flexural strength - restorative materials

Elastic modulus - restorative materials

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