Wednesday, November 7, 2018

Answer: Is this a safe treatment for caries?

One of my goals in writing this blog... 

... is to develop some skills that are useful in general.  You know, real skills for real problems.  
In medicine, new treatments and therapies come to market every so often, and many people wonder--is this good for me?  Does this actually work?  What are the risks and benefits? 
In general, how do you evaluate these things?  
This week we consider the dental treatment SDF (Silver Diamine Fluoride).  It's a simple, low-cost way to treat teeth with a coating that not only prevents future cavities (caries), but also seems able to reverse the damage in some existing cavities. 

Suppose that you're considering getting this treatment for someone in your family.  How would you go about doing some checking to see if it's effective, and if it's safe.  (As you know, not all medical treatments turn out to be safe in the end; think radioactive water as a spa treatment... a really bad idea.) 

Ideally, we--the SearchResearchers of the world--would be able to do some kind of sanity check before taking on a new treatment regime. 

This leads to today's Challenge: 
1.  How would you go about determining if SDF is right for you, your family, or your child?  What would you do to research this?  Would you get SDF? 
We SRS folks have a fairly high bar for this kind of research.  We'd like to find multiple lines of support from sources we trust.  So I began with a simple query to learn more about SDF treatment: 
     [ how does SDF treatment work ] 
And found a quick answer at the California Dental Association
"Silver diamine fluoride (SDF) is a topical medication used to slow down or stop dental decay in both primary and permanent teeth. ... When applied to a tooth with a cavity, SDF hardens the softened tooth structure, turning the damaged portion of the tooth black in color."  
That's from the California Dental Association (the CDA, which I happen to know is a reputable information provider).  But true to my skeptical nature, I double checked:  the CDA has been around since 1870 and has a great record of being both a philanthropic organization and a provider of information about dentistry in general. 
Now I have an idea what it is and how it works.  It's interesting that they go on to say that: 
"SDF is a conservative approach to managing dental decay and can be used on teeth where there is no pain or discomfort. It is particularly useful for providing dental care to individuals who present challenges to receiving traditional treatment because of their age, behavioral issues, or medical conditions." 
At this point, I wanted  a broad range of perspectives on SDF treatment, so I did a simpler query: 
     [ SDF treatment ] 
and started opening up multiple tabs side-by-side.  Here are some of the pages I opened up (and a few things I learned from each):  
1. Silver Diamine Fluoride: A New, Old Approach to Dental Caries Management.  This is a presentation by Scott L. Tomar (DMD, DrPH) from the 2016 American Association of Community Dental Programs conference.  It's a pretty nice summary (with lots of photos) about how SDF is used, when it should be used, and when it shouldn't.  It gives a bunch of references to other articles about SDF, including what the toxicity is (extraordinarily low) and generally seems very practical.  This is someone who uses SDF in his practice and comments on how it's accepted.  (And gives some very practical advice about its use:  "SDF stains the crap out of everything.")  The author also points out that silver fluoride has been used in Japan for 80 years without any issues.  (Interestingly, they used it to turn teeth black as a cosmetic treatment for teeth!)  
2.  Found several fact sheets about SDF by various community dental programs.  (Little Pearls dentistry for kids; America Academy for Pediatric Dentistry and others.  They all agree--SDF is great for kids because there's no pain, just a gentle painting of the teeth with a microbrush.  Some parts of the teeth do turn black, but only the parts that already have cavities.  As they point out, "that's how you know it's working!"  They correctly point out that inner cavities and difficult to reach cavities are probably not a concern, and visible caries need some other kind of treatment.  

With the query: 
     [ SDF for adults ] 
I found another trove of papers from reputable sources.  For instance, 
3.  A paper from the American Dental Association on Guidelines for SDF treatment of pediatric and special needs patients.  They're more cautious, but point out that SDF works exceptionally well for pediatric and special needs patients (who might have difficulty brushing their own teeth), but that the results are so intriguing that they're going to do additional research. 
4. But in another paper, A systematic review of silver diamine fluoride: Effectiveness and application in older adults.  This is another study of another kind of cavity, this time in older adults.  The results are amazingly good--the effectiveness is incredibly high, and no adverse side-effects were noted. 
To be ultra-cautious, I did searches for: 
     [ SDF adverse reactions ] 
     [ SDF side-effects ] 
and found nothing of consequence.  Everyone noted the staining (and in particular, that if you get it on the patients tongue, they'll have a black mark that will last for a week or so... but it's painless and goes away quickly).  
Overall I read about 5 papers from very different sources (some very technical, from highly regarded journals) and another 10 or so summaries for patients by different dentists who use SDF.  
I admit I was slightly skeptical about this universal acclaim, but then I looked up the cost of the standard SDF medicine that the dentists use.  It's $100/bottle.  Each bottle has around 250 drops, or around 40¢/drop.  Each drop treats around 5 teeth.  You can do the math... that's 8 cents / tooth: Nobody is making any money on this. It just looks like a very effective, very cheap therapy for dental cavities.  
Oddly enough, I actually had to visit my dentist this week and when I asked her about SDF she too was concerned about potential blackening, but "otherwise it sounds great for kids!"  (She also asked if I was studying dentistry... Apparently few people ask about SDF.    
A funny aside:  Since it was Halloween, we considered vampire teeth.. like these...

If I were a vampire, I'd worry about the number of cavities caused by an all-blood diet.  I know that the Maasai of the African veldt have a large amount of cow blood and milk in their diet, and surprisingly, they have very low rates of dental cavities. But if very modern vampires (who might consume larger amounts of sugar in their diets) are concerned about caries on their fangs, then SDF might be just the ticket.  And if they happen to turn black, then so much the better, eh? 

Search Lessons 

In this case, the research is pretty overwhelmingly positive.  As one of the research papers I read (UCSF Protocol for Caries Arrest Using Silver Diamine Fluoride: Rationale, Indications, and Consent, J Calif Dent Assoc. 2016 Jan; 44(1): 16–28) pointed out: 
 "Silver diamine fluoride is an inexpensive topical medicament used extensively in other countries to treat dental caries across the age spectrum. No other intervention approaches the ease of application and efficacy. Multiple randomized clinical trials – with hundreds of patients each – support use for caries treatment, thus substantiating an intervention that addresses an unmet need in American dentistry. In August 2014 the Food and Drug Administration (FDA) cleared the first silver diamine fluoride product for market, and as of April 2015 that product is available."
Although I spent a fair bit of time looking for side-effects and adverse side effects (my searches also included the fancy medical term "contraindications," I just didn't find anything.  
So.. would I use this for me and my family?  Yes, although probably not on the front teeth!  
This was a surprisingly simple SRS Challenge.  It was probably a 30 minute task to become comfortable with the current state of research on SDF.  That's a remarkable thing to say.  (I remember when this same kind of background research would have taken days!)  
Search on!  

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