A respected colleague recently engaged me in a passionate discussion about fluorides and dental sealants. We both agreed that, when placed properly and when they maintain their seal, sealants work. As a preventive treatment modality, sealants also reduce dental care costs tremendously. However, the care or management of such cases occupied our debate. She posed the reasoning of esthetics vs. function, which should be our point of concern when establishing post-treatment modalities.
To offer some background, Marilyn, a hygienist on the e-mail network [email protected], asked for suggestions on what type of fluoride should be used on children with sealants. This thread took many turns and led to many good discussions and sharing of information, some relating to evidence-based care and caries risk indexes. I, of course, focused on the issue of sealants being part of the composite family.
First, I realize it is essential to clarify the varying descriptions and categories surrounding sealants. Traditionally, sealants have been successfully implemented in primary and secondary teeth for caries prevention. A sealant should sufficiently flow into the depth of the pit and fissures and completely bathe the spaces between etched enamel rods without covering the entire occlusal surface. The technique, though changing daily, must be carried out fully, and the sealant must be evaluated continually to ensure the seal is retained.
Now, this is where it can get tricky. Categories of sealants include composite/ resin sealants, flowable resin-based composites (or preventive resin restorations - PRR), unfilled sealants, and filled sealants.
Composite/resin sealants are specially formulated unfilled resins. They are designed to penetrate any microcracks and/or defects after the finishing procedure of a newly placed definitive restoration. Composite/resin sealants prevent caries by sealing restoration margins. The microcracks may be responsible for wear and staining, and they are doorways for bacteria to invade the restoration/tooth interface. Some products in this category include PermaSeal (Ultradent), Optiguard (Kerr), and Fortify (Bisco).
Flowable composites or preventable resin restorations (PRR) are composite fillings diluted with unfilled resin material. The applications of PRRs are usually applied after any carious lesion or suspicious stains are debrided from the pit and fissures. The rationale of opening up the grooves, via a fissurotomy bur and/or air abrasion, is that the carious process may be developing deeper in the fissure complex - below what a clinical explorer can detect. So some clinicians question the old technique of hunting with an "explorer stick" approach to determine the presence of a carious lesion.
In addition, some clinicians challenge the diagnostic approach that relies heavily on radiographs. The theory here is that, by the time the radiolucency appears on a bitewing, the goal of minimal loss of healthy tooth structure has vanished. In response to the difficulties in assessing questionable occlusal caries, or to prevent the "W" word ("watch"), traditional assessment criteria can now be augmented to include newer diagnostic tools and techniques. For example, DIAGNOdent (KaVo) is a Class 2 laser that a clinician can shine on a tooth for a numerical score that indicates the presence of decay.
Many contemporary sealants have filler particles, such as glass or quartz, included in their materials. This is to increase the sealant's resistance to wear and dissolution in the oral environment. The filler particles can range from 20 to 60 percent. The viscosity of the material (ease of handling) relates directly to the filler content. Other properties of sealants to be considered are shade (clinician's and client's preference) and fluoride release.
Fluoride-releasing sealants add additional protection to surrounding tooth structures, and they have a potential to be "recharged" following a fluoride application. In lieu of this data, the fluoride factor should play heavy in a hygienist's decision when choosing a sealant product. Some sealants that release fluoride include UltraSeal XT plus (Ultradent), Helioseal F (Ivoclar-Vivadent), and EcuSeal (Zenith/DMG).
Cleaning out the pits and fissures before sealing the tooth used to be a simple matter. Now some techniques are advocating the opening of the crevices, which would make it an invasive procedure. If it becomes invasive, then it becomes a dental procedure (PRR) and hygienists would no longer be able to perform the sealant service.
So, after establishing good illumination and magnification, assessing the tooth with an explorer, taking appropriate radiographs (and/or using the DIAGNOdent), clean the crevices out with hydrogen peroxide or a cavity disinfectant (Consepsis, Ultradent) and a stiff brush or a sharp explorer. I have been combining the cleaning step with a disinfectant scrub because I would attempt to disinfect any other wound in the body prior to a placing a Band Aid or sutures.
Rinse the area out vigorously with air and water; the use of a rubber dam is ideal. This cleaning protocol is quick, inexpensive, and eliminates any chance of granular particles getting stuck in the pits and fissures.
Next, follow the manufacturer's directions for etching time and sealant placement. If a sealant containing filler particles is used, it will not "wear down" easily and should be inspected with articulating paper. Any overfilled areas need to be adjusted to avoid interfering with the normal occlusion. At the completion of the service, as with any procedure that involves acid etching, apply a topical fluoride.
The management of sealants includes evaluating retention. If a sealant falls out between hygiene sessions, then the tooth needs to be re-evaluated before placing another sealant. In addition, if the sealant appears to be leaking or staining, caution should be exercised prior to resealing, since you will want to avoid sealing in new caries underneath.
To answer the question that started this column - which fluoride is most appropriate to use with sealants? - I would have to say, "Play it safe and use neutral."
Again, I'm going back to the thought that sealants, especially filled ones, are part of the composite variety. The filler particles are similar in structure - but not in number - to the particles of composite restorations. Research involving glass ionomer cements, glass ionomer fillings, and composite restorations (both hybrid and microfill) shows how acidulated phosphate and stannous fluoride increase the surface roughness, causing increased degradation and wear in the restoration. The neutral fluorides appear to have no effect.
Admittedly, these papers are mainly performed in vitro and on composite restorations, but one can draw comparable conclusions in regard to sealants. The potential cumulative effect on the integrity of the sealant and its filler content must be carefully considered. If the surface becomes rougher, microorganisms could colonize at a faster rate, which would further affect retention.
Does this have a lot of documented clinical support? No. Does research on sealants need to increase and be performed in vivo? Yes. Is this management protocol only for esthetic preservation of the sealant? No. It is for protecting the integrity of the sealant's function.
Finally, here's a protocol to mull over. If we use a filled sealant material which is, for example, 60 percent filler particles (the same filler particles in a composite restoration), then do we have to place a resin sealant over the sealant?
Kristine A. Hodsdon, RDH, BS, presents seminars nationally about esthetic hygiene. She also has developed Pre-D Systems, a pre-diagnostic esthetic enrollment software for oral health professionals. She can be e-mailed at www.pre-d.com.
