Sunshine Smiles of Orange County

Is Fluoride Varnish Toxic? Age And Usage Recommendations You Should Know For Your Child

February 7, 2019
Posted By: Mikaeya Kalantari
Dentists and parents should talk about the benefits of fluoride varnish and its potential toxicity

Let's talk the F word today shall we!??  You know, that controversial word that all parents raise an eyebrow over and all news outlets love to debate over.  FLUORIDE.  There I said it, I'm a dentist and I want to talk today about Fluoride.  I'm guessing that you, like most people, have heard both pros and cons about the use of fluoride to prevent cavities yet I'm sure that you, like most people want to know more about the infamous F word.  Who should use it?  What true benefits does it provide?  Is it toxic!!??  Well today I would like to shed a little bit of scientific backed knowledge on the subject so that you may leave feeling more informed on the topic.

I would like to begin by emphasizing that fluoride is purely a PREVENTION tool and it does NOT reverse cavities, nor does its absence in the diet produce cavities.  It is merely a substance that aims to both prevent cavities from beginning in the first place, as well as to help stop or slow the progression of cavities that have already started.  Although fluoride can be beneficial in the ways just described - it should be made clear that a cavity forms due to the combination of plaque (ie. bacteria) and a sugar source which then dissolves the enamel on teeth.  This can occur with or without fluoride in the diet.  However, as you will see, fluoride can play a role in how easy this process is to both start, and the quickness with which it can progress.  Today we will talk a little bit about how fluoride works in this way, who would benefit most from fluoride use, and what types of side effects or drawbacks to fluoride treatments exist. I hope this article will leave you better informed to make decisions for both you and your children based on what YOU feel is best!

Parents should be aware of both the benefits and dangers of fluoride varnish. Let's talk about who really needs fluoride and why!

What Age Should A Child Begin Using Fluoride Varnish?

To back up a small step, let's talk about fluoride recommendations in general (toothpaste as well as in office treatments such as varnish).  The American Academy of Pediatric Dentistry (AAPD) and the American Academy of Pediatrics (AAP) recommend that a child begin using fluoride at the age of 2 (or sooner if cavity risk is high) to acquire all of the benefits of fluoride for the erupting and developing dentition.  A rice sized or smear of fluoridated toothpaste should be used for a child under 3 and a pea sized amount for children 3-6 years old 9.  Even though this is young, the benefit of fluoride at this age is actually more beneficial as the fluoride has time to incorporate into the enamel of the teeth as they are developing - especially the permanent dentition.  With this said, a child's caries risk should always be taken into account prior to the recommendation of any fluoride.  Factors that are considered in determining a person's cavity risk are things such as: diet, brushing and flossing habits, family history of cavities, previous history of cavities, and enamel defects.  In a patient that may be considered low risk for cavities then in-office fluoride treatment may likely not be as beneficial.  This is the ideal time for the dentist and parent/patient to begin having a conversation about what risk factors for cavities exist, and if fluoride treatments are beneficial or not.

What Are The Benefits Of Fluoride Varnish For My Child?

Research has shown that the fluoride ion acts in several different ways to prevent cavities and slow down cavity progression.  The benefit of greatest importance is the process of the fluoride actually incorporating into the enamel structure, and in doing so, the enamel becomes less likely to be broken down by acid producing bacteria 1.  This benefit comes from using fluoridated toothpaste, drinking fluoridated water, and having in-office fluoride treatments placed on the teeth.  I tell parents and my patients that fluoride can act as a "shield" in this way - just an extra layer of protection from assault from harmful bacteria.  Just like a shield though, teeth with fluoride can still be subjected to harm, it just takes larger assaults to bring it about.

age recommendations for fluoride varnish

Another beneficial mechanism of fluoride is that its presence helps to deter certain enzymes of bacteria that lead to the production of acid in the mouth 1.  In simpler terms: more fluoride = less acid in the mouth, and acid is what dissolves enamel thereby causing cavities.  And finally, I will mention that excess stores of fluoride in the saliva, or that from drinking water, acts in small amounts to help remineralize or slow the progression of decay in a way similar to the "shield" example that we used above 2.  Again, I will reiterate that fluoride will NOT reverse cavities, but can help remineralize to a certain degree and slow their progression.

What Percentage Of Fluoride Is In Varnish And Toothpaste?

As fluoride varnish is beginning to be the standard type of fluoride treatment offered in most dental offices, we will primarily discuss this type of treatment today.  The percentage of standard fluoride varnish is 5% NaF.   At this percentage this means the dentist will be using anywhere from 2-5 mg total of the fluoride ion (depending on how much varnish is used).  There is another type of fluoride varnish (the type used in our office at Sunshine Smiles of Orange County) and it is 2.5 % NaF.  This means that the dentist will be using anywhere from 1-2.5 mg of fluoride (dependent upon how much of the varnish is used).  Studies have shown that the 2.5% Fluoride varnish is just as effective, if not more so, in enamel uptake and fluoride release as the 5% varnish 8. In comparison, traditional toothpaste contains anywhere from .1-.25 mg per use.   A chart for your reference is shown below, you will also see listed toxic dosages which we will discuss in further detail in the following section.

Is Fluoride Varnish Toxic For A Child?

Let's begin to answer this question by understanding where exactly the fluoride that we consume via our mouths ends up.  Majority of fluoride is absorbed by the body via the GI tract (stomach and intestines) and is dependent upon many things including the contents and pH of the stomach at the time 3,4.  Unabsorbed fluoride leaves the body while the remainder travels throughout the body into the bones 3.  It is a known fact that growing children tend to uptake fluoride into their bodies more easily than adults do as their bones continue to form and grow, and it should also be stated that fluoride is known to cross the placenta in pregnant mothers 3.  This means that fluoride that a mother consumes can end up in the bodies of the developing child.  This process is a reversible one, which means that fluoride is able to leave the mineralized structures when needed (a majority of which is then excreted by the body but is dependent upon several factors) 5,6.  Therefore, fluoride concentration within the body itself is always subject to fluctuation. 

Regarding toxicity, there are levels of fluoride within the body that prove to be toxic and lead to harmful effects in a person, these levels are based upon weight and apply to both children and adults.  The accepted toxic level is 5 mg/kg of weight for a person which can lead to side effects such as nausea, vomiting, hypotension, renal and respiratory complications, and coma in it's acute form 3.  Lesser toxic levels can lead to more chronic side effects such as dental and skeletal fluorosis and gastric concerns 3

Let's now use an example so you can better understand toxic fluoride levels in a realistic situation.  If your child weighs approximately 30 pounds, they would need to ingest over 65 mg of fluoride to show signs of toxicity.  With this said, it should be stated that while this does mean that there is in fact a toxic level of fluoride, keep in mind that there are toxic levels of several things that we as humans consume and come in constant contact with on a daily basis.  As you have read above, the fluoride concentration used in today's toothpastes and dental office applied fluorides are much lower than the toxic dose of fluoride and can be seen in the chart below.  Although accidental fluoride poisoning does happen, the vast majority of fluoride poisoning cases comes from accidental ingestion of large amounts of toothpaste, and not from overuse of in office fluoride treatments 7.

The toxic dose of fluoride compared to other fluoride containing products puts it all into perspective. Who benefits most from fluoride? Read more to see!

The purpose of bringing to light these toxic effects as a dental professional is in the spirit of education and in hopes that this will open the lines of communication between parents/patients and their dentists.  In my opinion, when discussing the need for fluoride use (both in at home toothpastes or rinses and the in office applied treatments) the parent/patient and dentist should take into consideration the following items.

Factors To Consider When Determining A Patient's Need For Fluoride

- The Patient's Caries Risk (including diet and oral home care)

- The Amount of Fluoride In Patient's Drinking Water At Home Or School (if tap water is not fluoridated this could be a reason to strongly consider fluoride treatment and supplements)

- The Patient's/Parent's Wishes

Is Fluoride Varnish Safe To Use With Allergies?

While majority of fluoride in office treatments are perfectly safe for those with allergies, it should be noted that there are some instances where patients have had strong and even severe allergic reaction upon receiving their fluoride treatments.  This has happened in cases where cross contamination with allergens in manufacturing facilities occurs, or when binding products within the fluoride varnish matrix contain trace amounts of allergens.  If your child has a severe, life threatening allergy, you should have a discussion with your dentist to ensure that they are familiar with both the full list of ingredients in their office fluoride treatments, but also familiar with the manufacturing process involved.  The fluoride varnish that we use in our office (FluoriMax by Elevate Oral Care) has been confirmed to be free of: milk, dyes, gluten, eggs, peanuts, tree nuts, pine, fish, shellfish, soy wheat, sunflower seeds, and sesame seeds.  The pharmaceutical facility that produces this specific varnish has also confirmed that they do not process any of the allergens noted above as well.  Of course, in a patient with life threatening allergies, you can never be too careful and a decision to use a product for the first time should never be taken lightly and always researched!

I hope that this has helped to shed a little more light on the use of fluoride for dental purposes and made you feel more comfortable and confident in having a discussion with your dental provider.  At the end of the day, all dentists want one thing: for our patient's to be happy and to have the tools and services they need to have optimum oral health.  Sometimes this is achieved with the use of fluoride, and other times it is not.... but the decision should always be based on open lines of communication.  See, the F word isn't so scary, now is it!?

Further Reading

To review the AAPD Guideline On Fluoride Therapy, you can directly view their Reference Manual

To read more evidence based fluoride therapy facts, view this brief from the Association of State and Territorial Dental Directors Fluoride Committee

Research Cited

1. Levine M. Topics in dental biochemistry. Berlin, Germany: Springer Science & Business Media; 2010.

2. Buzalaf MA, Pessan JP, Honorio HM, ten Cate JM. Mechanism of action of fluoride for caries control. Monogr. Oral Sci. 2011; 22:97-114.

3. Ullah R., Zafar MS., Shahani N. Potential fluoride toxicity from oral medicaments: A review. Iran J. Basic Med. Sci. 2017. 20(8) 841-848.

4. Barbier O., Arreola- Mendoza L, Del Razo LM. Molecular mechanisms of fluoride toxicity. Chem Biol, Interact 2010. 188:319-333.

5. Buzalaf MA, Whitford GM. Fluoride metabolism. Monogr Oral Sci. 2011. 22:20-36.

6. Ozsvath DL. Fluoride and environmental health: a review. Rev Environ Sci Bio Technol. 2009. 8:59-79.

7. Martinez-Mier EA. Fluoride: it's metabolism, toxicity, and role in dental health. J Evid Based Complement Alternat Med. 2012. 17:28-32.

8. Ahmed I., Coleman SS., Carey CM. Fluoride release and uptake into hydroxyapatite from experimental dental varnish. University of Colorado.

9. American Academy of Pediatric Dentistry Reference Manual. Fluoride Therapy. 2018. V40 (6) 250-253



Dr. Mikaeya Kalantari has been a practicing pediatric dentist for over 7 years working in both the children's hospital setting and private practice.  She has had a wealth of experience treating children of all ages, and medical conditions. When it comes to serving children, she feels the importance of communication between the dentist and parent can not be emphasized enough. Dr. Kalantari practices in her family owned dental office in Mission Viejo, California. 

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