FLUORIDE RELEASE AND RECHARGE OF DIFFERENT MATERIALS

GLASS IONOMER

The releasing and recharge ability of the material fully depends on the glass particle,particularly the amount of hydrogel layer over glass filler.

In case of glass ionomer the powder liquid reaction is acid base reaction and the reaction results in more well defined amount of hydrogel matrix over the glass particle.

So that glass ionomer release large amount of fluoride initially(hydrogel matrix) and release reduces with time, at the same time the released fluoride is recharged with exernal fluoride source such as fluoride solution,fluoride varnish,fluoride tooth paste.fluoride mouthrinse.

The initial "burst" effect is only seen in glass ionomer,compomer and giomer does on exibit initial "burst".


COMPOMER
In Compomer, polyacrylic acid and resin matrix combined into one molecule.

Initially polymerization reaction takes place followed by subsequent sorption of water leads to ionization of acid and acid base reaction takes place at the slow rate.The fluoride release is during first sevan days in expected to be low.

The acid base reaction is less prominent in this case and hydrogel layer formed in small part.

In Compomer fluoride release is less when compared to glass ionomer and the recharging ability is not seen case of compomer.

GIOMER
In Giomer the fluoride release is similar to that of glass ionomer,the difference of giomer from compomer in fluoride release is both contain glass ionomer and resin matrix but in case of giomer the glass particles are pre-reacted with polyacrylic acid before blending with resin matrix.

The hydrogel layer is more extensive in giomer similar to that of glass ionomer.

Fluoride release in case of giomer is by exchange mechanism in the direction of lower fluoride concentration from higher concentration.The existence of a CONCENTRATION GRADIENT is the driving force for fluoride release.

Fluoride release of giomer was greaer than other materials at day sevan and it became significantly lower at day due to diminishing fluoride gradient

REFERENCES
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