Is there any evidence that fluoride release from GIC may cause porosity or mechanical weakening of the materials?
[A]Although different authors are noncommittal, yet the following paper does proclaim that the fluoride release DOES NOT INCREASE POROSITY. The abstract of this paper is reproduced for your kind perusal.
Rev Belge Med Dent (1984). 1996;51(1):9-21.
[The formulation of glass ionomer cements and the amount of fluoride].
[Article in French]
De Moor R.
Abstract
The glass-ionomer cements (GIC) were developed in the late sixties. The set cement is the result of an acid-base reaction between an ion-leachable glass (the base) and a poly (alkenoic acid). Through the years, the number of applications of these GIC has increased steadily. The evolution has to be referred to the fact that the composition of both acid and base can be changed considerably. This has resulted in the marketing of GIC with different physical and chemical formulations. Furthermore, resin-modified GIC were introduced in the late eighties. One of the major GIC advantages remains the fluoride release. The fluoride in GIC is a component of the material itself and is not added afterwards. [[[Beneficial for the GIC in this respect is that the released fluoride is not of structural importance in the set cement. Furthermore, the fluoride release does not result ,on itself, in a reduction of physical properties or an increase in porosity.]]]
In addition, I, hereby, reproduce findings of a few other authors along with references:
[B]Fluoride-releasing materials have been shown in these models to reduce demineralization of both enamel and dentin compared with a material that does not release fluoride.
REFERENCE:
Adv Dent Res. 1995 Nov;9(3):315-23; discussion 324-31.
[C]As a small change in fluoride level affects the caries balance, it is conceivable that fluoride release from dental materials reduces secondary caries, or caries around orthodontic brackets.
REFERENCE:
Ned Tijdschr Tandheelkd. 1996 Nov;103(11):464-7.
[D]The anticariogenic action is principally due to the fluoride release of the materials. That's why it is necessary to define the acceptable level of fluoride release, which is required to have anticariogenic action.
REFERENCE:
Rev Belge Med Dent (1984). 1998;53(1):278-94.
The fluoride ion is an addition to the original glass melt as an oxide scavenger and becomes incorporated into the finished glass powder but it is not an essential component. It can therefore be released separately without making any difference to the physical properties of the glass particles. It remains available from the surface of the glass particles and is therefore available for uptake into surrounding tooth structure with the potential for its normal anti-cariogenic activities through increasing resistance to demineralisation of normal tooth structure. It is highly unlikely that it would increase the level of porosity or reduce the physical properties of the restorative material and there appears to be no evidence that it is involved in these areas.
Dear Graham Mount; I am very thankful to you for the kind attention. It is an honour for me. I have already learnt a lot from you. The book, "An atlas of Glass ionomer cement" I found it very useful for understanding the subject and still benefiting. Best regards
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