Definition:
Resin-modified glass ionomer cement (RMGIC) is a hybrid restorative material that combines the traditional acid–base reaction of conventional glass ionomer cement with a resin polymerisation reaction.
It is a light-curable, fluoride-releasing, tooth-coloured material that chemically bonds to tooth structure while providing improved mechanical properties and faster setting compared to conventional GIC.
What are RMGICs made from?
RMGICs contain the same basic components as conventional GICs, with the addition of a resin component.
Powder:
Calcium fluoro-aluminosilicate glass particles (often strontium-containing)
Calcium fluoride → reduces fusion temperature, promotes early cross-linking, provides fluoride release
Silica → forms a siliceous gel providing strength and translucency
Aluminium oxide → controls ion release and contributes to compressive strength
Photoinitiator system → allows light-activated polymerisation
Liquid:
Polyalkenoic acid (similar to conventional GIC)
Polyacrylic acid or acrylic acid copolymers
Water
Hydrophilic resin monomer (commonly HEMA – hydroxyethyl methacrylate)
Tartaric acid (to improve working time and handling)
Setting Reaction
RMGIC undergoes two simultaneous setting reactions:
Acid–Base Reaction (GIC component)
Dissolution → acid attacks the glass surface, releasing Ca²⁺, Al³⁺, F⁻
Gelation and hardening → ionic cross-linking forms a polyalkenoate matrix
Hydration → maturation continues over 24 hours
Resin Polymerisation Reaction
Light activation initiates free radical polymerisation of the resin component
Rapid early strength development
Improved resistance to early moisture contamination
Because of this dual reaction, RMGIC sets faster and achieves higher early strength than conventional GIC
Tooth – RMGIC Interaction
Chemical adhesion occurs to mineralised enamel and dentine via ionic bonding (as in conventional GIC).
The resin component also provides additional micromechanical interlocking.
Mild conditioning enhances both mechanisms.
Clinical Uses:
Restorations: Class I (small), II (non-stress areas), III, V and cervical lesions
Luting agent: crowns, bridges, orthodontic brackets and bands
Base or liner: under composite restorations (sandwich technique)
Paediatric dentistry: useful where moisture control is challenging
Root caries: fluoride-releasing restorative option
Core build-ups in low-stress situations