Sealants: The Choices & What to Look For!!

The dental profession is offered a variety of choices when it comes to selecting a pit and fissure sealant. Also the public's perception of the need and benefits of sealants has also come a long way since sealants were first introduced. The public now widely accepts sealants and also expects a good result! However, recent public events, such as questioning sealant composition and hearing about failed sealants that have massive decay beneath them, may be challenging the public's trust.

Pit and fissure sealants are intended to seal surface defects of teeth (particularly in young children), to prevent food accumulation in these areas, and to prevent decay of the tooth. Sealants can and should last for several years. Sealants are not intended to last forever and require regular check ups. The problems with sealants start with undiagnosed decay that is present before a sealant is placed, or when a sealant leaks, and this leads to decay that is not observed, or can not be easily detected.

To help understand these problems and solutions, let's take a look at the choices of sealants today. Several categories exist according to composition and rationale for selection. Almost all sealants used in the US are light-cured. That means they are cured, or made to harden, by visible light (an intense blue light - not an ultraviolet or UV light).

By focusing on the components of the sealant, we can further understand sealant use. Almost all sealants release fluoride to help protect the tooth from decay and to help control bacterial growth around the sealant. (See my previous posting on the benefits of fluoride in dentistry.)

Let's continue with what are considered traditional sealants. These may be either: glass ionomers or a filled resin. The glass ionomers contain water with an acid liquid that reacts with a glass powder. Proponents of this group prefer them because they contain water and therefore are better tolerated in the moist environment of the mouth. Glass ionomers typically for this same reason, containing water, "dissolve" more in the mouth, and are therefore, generally weaker and do not last as long in the mouth, as resin based sealants.

Resin based sealants usually do not contain water and may be more technique sensitive than glass ionomer materials. These sealants require good tooth isolation. Recently, some sealants in this category have been introduced that do contain acid materials and interact better with the tooth. These materials, however, do not replace the need for good tooth isolation and tooth etching to achieve good retention. To differentiate this acid-like resin category, some people use use the term hydrophilic (water loving), to help describe how they are similar to the glass ionomers. The term hydrophilic is, however, a relative term, and care is suggested not to alter good technique in placing them. This means good tooth isolation to avoid saliva contamination and acid etching the tooth before placement. Some of you are very aware of the clinical problems caused by this group! Proper sealant placement also requires a thorough examination of the tooth surface to make sure no hidden decay exists.

More recent advances are clear sealants that allow the dentist or hygienist to see through the sealant. This allows observation of the tooth after the sealant is placed. The very question of what happens beneath a traditional sealant prevents many well intentioned practitioners from placing sealants at all! Today clear, resin-based sealants, now with nano sized filler particles (that do not make them opaque but make them very strong), are available. The use of new laser devices for detecting decay (so that you can also measure any activity beneath the sealant), has also been FDA approved for some of these clear sealants, but not all of them! The question in sealant selection thus becomes: Isn't it more important to see what's happening beneath the sealant, than to actually see the sealant itself?

The last category of sealants, that I would like to describe, are the high fluoride, 5% NaF, containing sealants. These sealants bring us back to one of our primary reasons for placing sealants to begin with: to protect the tooth. This group provides a higher amount of fluoride than traditional resin sealants to protect those individuals who may be at greater risk. Such risk factors may include: difficulty in brushing, patient compliance, health factors, absence of fluoridated water or supplemental fluoride, or lack of access to good dental care. For these patients a 5% NaF sealant should be considered.

With these improvements and public acceptance of sealants, I believe there should also be a greater commitment to following the progress of sealants. W
ith so many sealant choices available I invite the profession and public to become more involved in considering different material options. This involves selecting the best sealant to fit your goals. This should also include becoming more vigilant as to what happens after a sealant is placed. In other words, Keep looking!! The long term success of sealant placement and the health of that tooth depends on good follow-up.

Thanks for reading along, I hope this discussion helps clarify the many choices available in sealants, their intended purposes, and lastly some advice on how to make them work for you. This is a rapidly changing field.

For those interested in sealants, or the components of dental composites, watch for one of my next postings on Bis-Phenol A and Bis-GMA, or send me an e-mail.

Regards,
Jan

Also for further information see my article: "To Seal or Not to Seal - The Clear Solution." Click on image below to read article.






Dental Sealant Selection and BPA (Bis-Phenol A)

Recently published debates and news stories about Bis-Phenol A (BPA) being found in dental products (particularly dental sealants), baby bottles, and now food, have caused concern in the general public and within the dental industry. My comments relate to dental products and the dental industry. BPA is a chemical compound used to make dental resins. BPA has been extensively researched, and discussed as having potentially adverse health effects, particularly related to estrogenic effects.

Before I weigh in on this subject, let me offer my background. I am a polymer chemist, a dental materials specialist, with training in cell culture and animal testing of dental monomers, a dental manufacturer, a dental educator, and someone who has evaluated, developed, and marketed dental sealants for more than 25 years.

BPA is a starting component for making Bis-GMA, a very common dental monomer used in a wide variety of dental products. In making Bis-GMA it is possible that not all of the BPA is converted into Bis-GMA and that some BPA can be found in the final dental product. Some BPA, in even smaller amounts, may leach out of the final product. The question becomes: What are the effects of a very small amount of BPA on the patient?

So far, several studies have shown that at much higher concentrations, such compounds can have an impact upon the development of cells in the laboratory. This is not news and has been known for decades, and not just for BPA. The real question here is: Are the clinical amounts of BPA causing any adverse effects on the patient? So far the answer is no! However, the door should not be closed on this issue or patient concerns.

We are surrounded by thousands of compounds that have known health risks. I understand the concern. Public safety and patient health is something many of us are committed to. This is also the primary responsibility of the FDA. Dental products of this type, both sealants and composites, are regulated by the FDA. Continued study of BPA is underway, as well as, thousands of other compounds. Many of us monitor or are directly involved in these studies and carefully select dental components from materials known to be safe.

So, why is there so much discussion about this topic in the dental industry when no definitive evidence exists? Part of the answer lies with dental companies, some of whose sealants do not contain Bis-GMA or BPA, are making a big fuss about this issue. They are paying advertising agencies and speakers, to stir up a storm over this issue. It doesn't matter that these same companies also sell sealants and composites that are based upon Bis-GMA. Do they bother to tell the public this as well? Why don't they take their Bis-GMA containing products off the market?

Are these same companies spending any money to answer the basic question, is Bis-GMA or BPA, as it is supplied to the industry and patient, safe? What do you think?

So, returning to BPA and Bis-GMA. Bis-GMA has been used in the dental industry for decades. Bis-GMA is among the most widely used monomers in all of dentistry. Are there any studies linking Bis-GMA containing products to any adverse health effect? No. Have the dental restorations that contain Bis-GMA provided great service in restoring function and esthetics to the patient? Yes. Can we continue to improve the development and testing of dental restorations based upon such materials? Of course! However, to promote such media attention is really dis-ingenuous.

From what we know today, Bis-GMA containing sealants and composites are safe, and should continue to be used in dental materials.

Regards, Jan


For those who have further interest, or are not convinced, see the American Dental Association position statement on this subject at: http://www.ada.org/prof/resources/positions/statements/bisphenola.asp

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



Ever Seen a Stained Composite Restoration?

I think the answer is yes, for just about all of us? Keep that picture in mind. Think of the adjacent enamel, good condition. Recall the appearance of the bulk of the composite, generally, also in good condition. So what's the problem? The image I am trying to have you conjure up is the problem that I would like to address, that of marginal staining and leakage of a composite restoration. The problem starts at the margin. The interface between the tooth, in this case, primarily etched enamel, and the composite. Ooops, I almost forgot my point

The material that is in between the tooth and the composite that brought all this upon us was the bonding agent. Yes, bonding agents leak! We are all now familiar with water trees, the fluid transfer between the layers of: dentin, bonding agent and the composite within a restoration. Where does this also occur, but in this case, ultimately causes us to replace the restoration, at the exposed margins! See our studies on bonding agent leakage vs. self adhesive materials, posted on our website, and shown below.

It is amazing to me that some leading clinicians identify this as the number one leading cause of replacing existing composite restorations, while others deny that this even occurs.

So what's the point? Keep the bonding agents, if at all possible, away from the margins and avoid pooling of the bonding agent. And the suggestion, where possible use a self adhesive material, such as Aura Veneer Cement or Aura VLC Cement either with or with out a bonding agent, but please keep the bonding agent away from the margins, they leak, like crazy!!

What do you think? Thanks for your input. Let's keep it going.
All the best, Jan
















The above study compared the leakage of different materials such as bonding agent with composite, glass ionomers, and self adhesive materials without bonding agents. Four groups of seven teeth each were evaluated. Shown above is a synopsis of the results. Call for further details of the study design and results.

The Self Adhesive Veneer Cement Group


Denali introduced, in 2008, the first self adhesive veneer cement. Just like the self adhesive resin cements, others are now jumping in too. Before too much confusion ensues, I would like to break down the intent of this product category and adjunct product selection, notably bonding agents.

Veneers today come in many different materials, thicknesses, and with a variety of different placement protocols. Up until 2008, and Aura Veneer Cement, all required the use of bonding agents. Not being afraid to jump into a new, more efficient way to practice dentistry, we introduced Aura Veneer Cement, that does not require bonding agents. Read on. Recall the different placement protocols part. The trend in veneers is a conservative, minimal prep design with very little or no enamel preparation. The key element here is that we are still in enamel. Today the best bonding to enamel still starts with acid etching with phosphoric acid. The so-called SE bonding agents are intended for dentin, not enamel, just read the directions carefully when it comes to un-cut or minimally cut enamel. To my knowledge only one bonding agent claims to be effective on un-cut enamel (call for the name, don't worry its not mine). Truly robust bonding agents also exist, call for this recommendation.

Back to veneers. So for placement on enamel, Aura Veneer recommends acid etching enamel and does not suggest the use of dentin bonding agents on enamel. Bonding agents are not only not necessary, but are counter-productive (this will be my next blog). Bond strength to etched enamel has been shown to be more than sufficient, but again the proof is in the pudding, see our documented cases. (Just ask yourself, have you ever had to take off an old veneer that was bonded to enamel? Staining at the margins, right?, this is why it had to come off. Well bonded though right, but what did it look like underneath?

Below, on the left, are veneers bonded many years ago. The teeth show inter-proximal staining, which required removal of the veneers. Shown next, are the same teeth after the veneers have been removed. Inter-proximal decay is evident. This illustrates the point of leaking veneers that were bonded many years ago, using a bonding agent.








Next in placement protocol comes significant enamel reduction, with a mixed surface of enamel and dentin. Here some bonding agent may be beneficial, the choice is yours. The self etching bonding agents are preferred by some using Aura Veneer Cement so they don't have to use phosphoric acid. Acid etching however is another alternative. When it comes to sclerotic dentin, or all dentin, then use of a dentin bonding agent is recommended.


Maybe we've come full circle. We are now fully in dentin, and have the choice of what cement and bonding agents to use. At this point you may ask why not just use a traditional self adhesive resin cement or a glass ionomer. The reasons why not, are at least two. The self adhesive resin cements are all dual cure and notoriously suffer from yellowing. Glass ionomers, even the resin modified variety, must contain water and therefore are more soluble than resin cements. Remember we are after a long-term aesthetic result. Yellowing and staining a few years down the road is not acceptable today.The second reason is that veneers are more prone to coming off as opposed to a crown (less retention, particularly lateral forces), recall those of you old enough - what used to happen to veneers in the early 1980's? So for these reasons when it comes to dentin only, go ahead and use a dentin bonding agent. I have fought this battle before with the self adhesive resin cements, I know many of you are in love with your bonding agents and with shear bond strength testing. But please, if possible, keep the bonding agent away from the margins! As promised I will show you why next time.

Meanwhile check out some of our clinical cases using Aura Veneer and Aura VLC, many thanks to our talented clinicians for supplying them!

Thanks again. Chime in! I look forward to your comments.
Regards, Jan


Self Adhesive and Self Etching - What's the Difference ?

Self adhesive and self etching are common dental terms that are often mixed up or misunderstood. This all started with self-etching (SE) adhesives. These SE products were intended to be bonding agents with water miscible solvents, as a dentin bonding procedure, and as an alternative to using phosphoric acid to etch, primarily dentin. Remember these products are called dentin bonding agents, not enamel bonding agents. SE bonding agents have a pH between 0 and 1.5. So far so good. The properties of dentin bonding agents that made them an alternative to phosphoric acid was that they had a pH low enough to etch dentin, and a few cases actually etch enamel.

Next came the self adhesive resin cements. These products do not have a low enough pH to effectively etch dentin, but have a pH usually between 1.5 and 3. As a consequence the self adhesive products are not meant to infer that either etching or bonding agents would not be a benefit to their use, only that they have a moderately acidic pH. It is in fact true that self adhesive cements have enough retention by themselves, not using a bonding agent or acid etching, to hold a crown in place. In this case retention is the key word, not shear bond strength (that testing is a horse of another color!)).

Self adhesive materials in fact perform even better, have greater retention, when used with a bonding agent to dentin. Self adhesive resin cements have proven themselves effective in crown retention now for many, many years. A little boasting here, I have probably the longest surviving crown cemented with a self adhesive cement. (call me for the details). Recall all the dis-belief, you know who you are, when these products were being introduced. Of course their testing was all wrong. The proof has now been shown to be in the pudding! And today we have many self adhesive resin cements on the market.

Thanks for reading along. Join in the banter. Next I will address what's going on with the self adhesive veneer cement products. By the way, check out Aura Veneer Cement and Aura VLC Cement, the first self adhesive VLC cement.



Thanks again. Jan.