Fluoride, Fluoride, and more Fluoride!!

Before I begin, allow me to digress a bit.

Some of my earlier work had to do with measuring fluoride release from such things as glass ionomer restoratives and then cements. This led me into studies on whether fluoride could be found in bottled drinking water. Some bottled water does contain very small amounts of fluoride, most do not. This then led to studies of fluoride in fruit juices. Many fruit juices do contain fluoride, again at very low levels, some however at high levels due to pesticide contamination!! (You may remember the over use of pesticides on apples a number of years ago? The same thing happens with pesticide use on grapes and it contaminates grape fruit juices. Our reporting of this received the largest number of reader responses ever, up to that time, in the Boston Herald). At this point the anti-fluoridationist's picked up my work and I became associated with, at least in their literature, their cause. This actually became more cited than the original work, who could have known! For the record, I am in favor of fluoride use to prevent tooth decay, but of course in the right amount and in the right place. That leads me to my point, what are the benefits and appropriate uses of fluoride in dentistry?


Many of us know the classic work of Dr. H.Trendley Dean. Dr. Dean showed how fluoride in drinking water (again in the right amounts) can lead to lower acid solubility of enamel that has developed in the presence of fluoride. Here the key phrase is developed in the presence of fluoride. Pediatric dentists know this very well. The tooth needs to be developing in order to take up the fluoride. In everyday language this means young children benefit.

So why fluoride in dental materials for restorative applications when we are older? The same benefits have been shown, but to a lesser degree, from fluoride release from dental materials. In general, this means fluoride on the outside surface of the tooth where the restorative material is placed, not throughout the whole tooth.There are trade-offs however. Fluoride release is often accompanied by material weakening. The big picture however is different.


The amount of fluoride from a dental material is very low compared to other common sources such as topical fluoride gels and many toothpastes. Parts per million from dental materials versus 1.23 % from a topical gel or a preventive 1.1 % NaF toothpaste, a big difference! Also, fluoride release from dental materials comes at the beginning and then decreases after a few days of an initial burst. O.K. I hear some of you saying, "what about those materials that can be recharged, like the glass ionomers"? Well, I would have maybe conceded you this point, until to my surprise, we learned that not all glass ionomers release fluoride (see the work of I.F. Stannard and S.R. Stannard, "Fluoride Release and Physical Properties of High Fluoride Materials", J.D.R., Special Issue, 0489, 2008) and not all are rechargeable. Further, of those that are rechargeable, many do not obtain their original levels! So, I am re-thinking that argument about the benefits of fluoride recharging, if it ever was valid, particularly compared to other fluoride sources.

So what are we left with? In dental materials, we have known for a long time that the much older silicate cements, though they had higher solubilities and did not last, they also did not lead generally to secondary decay. So fluoride release from a dental material can be a good thing. I am an advocate of fluoride release from sealants, particularly when little enamel is removed. I am less in favor of fluoride release from cements, where we really want a long term seal. I am also in favor of 5% NaF materials such as varnishes, (wow! haven't varnishes become popular all of a sudden?) and Aura Lay XF (our 5% NaF pit and fissure sealant for at risk patients). I can hear now the manufacturers and marketing people, "just try to sell a restorative dental material today without fluoride". Well maybe I've started the debate again, but hopefully this time a little closer to home!

Let me know what you think. This should be good!
Thanks for your comments, just play nice.
Jan