WHAT AND WHY
We know what causes tooth decay, and we know what the lifestyle and oral hygiene measures are that will reduce our chances of getting it to the minimum. That minimum, unfortunately, is often not zero. Life is not fair. People with poor dental hygiene habits get cavities, but people with perfect dental discipline get cavities, too. The good news is there’s another step we can take to protect teeth from decay and its consequences.
We can place a protective barrier on the tooth surfaces that are especially vulnerable to decay. This is the concept behind dental sealants, which have been in use since the 1960’s. Where our natural tooth enamel is most frequently attacked by bacteria’s acid secretions, we can apply a layer of inert plastic which these acids don’t affect.
WHO AND WHEN
The best time to apply dental sealants is as soon as the target tooth has fully erupted. As long as that surface is exposed, it’s at risk for decay and caries. Sealants are generally not applied to teeth with decay, cavities, or fillings. They’re a preventative measure, not a remedial one.
Some practitioners do apply sealant to baby teeth since problems at that stage can cascade into longer-term issues with the permanent teeth. The primary targets, though, are the adult molars and premolars, ideally as each completes erupting. These are the most heavily fissured teeth. The age range, then, is about 6 – 12.
Adults can and do benefit from sealants as well, as long as there are vulnerable surfaces that are free of decay and fillings.
WHERE AND WHY
The chewing (occlusal) surfaces of molars and premolars feature grooves (fissures) whose function is to enhance the chewing effectiveness of those teeth. The teeth of the teeth, so to speak. This physical feature’s downside is increased vulnerability to decay. About 80% of the tooth decay seen in kids is in these fissures.
There are three reasons for this. First, the fissured structure greatly increases the total surface area of the tooth, so there’s more carrying capacity for food, debris, and the resulting plaque. Second, it’s hard to clean these fissures, which by their nature are narrow and deep. Finally, the enamel lying at the base of these grooves is relatively thin, and so is more easily penetrated by bacterial acids.
Pits and fissures are sometimes found elsewhere, and wherever they are found, dental sealant can be considered.
The application of dental sealants is in principle painless, minimally invasive, and quick. Let’s step through the process.
The procedure begins with a thorough cleaning of the target surface. This is the first step in preparing the surface to bond properly with the sealant. The dentist or hygienist puts a small rotary brush in the dentist’s drill, and scrubs the area with special attention to the fissures.
If it appears that the brush was unable to completely clean out the fissures, there are two additional techniques that can be used to complete the job. Air-abrasion uses a device that’s like a tiny sandblaster. Messy, but effective and painless. Enameloplasty is the use of the dental drill to tease out any remaining debris. The amount of pressure applied is so insignificant that this, too, is painless.
The tooth is then rinsed and dried, to prepare for the second stage of conditioning the surface for bonding to the sealant.
What happens next is the dentist applies etching gel, a mild phosphoric acid solution, to the target surface. The liquid flows into the tiniest reaches of the grooves, covering the entire target surface, and is allowed to sit for 20-60 seconds. It’s then rinsed off.
The gel accomplishes two things. Most importantly, it textures the tooth surfaces it comes into contact with, so the sealant can get a better grip when bonding with the tooth. It also kills any bacteria hiding on the chewing surface or in the grooves. Etching gel does have a sour taste but won’t hurt if it gets on your tongue or gums.
The rinsed, conditioned tooth is now dried with an air gun. From this point, until the sealant is applied, it is essential that the prepared surface stay completely dry. Even tiny quantities of saliva can degrade the bonding process, making it necessary to repeat the etching. For this reason, the patient’s cooperation is especially important at this stage of things. The dentist may use cotton, gauze, or a latex dental dam to isolate the tooth from saliva contamination.
Now comes the application of the sealant itself, which is done either with a brush or with a small syringe. The sealant is a liquid, so it fills every space in the grooves and fissures completely.
Two types of sealant are in current use. The most widely used is the resin type, which once applied to the tooth is “cured”, or set, by shining a special blue light on it for about 60 seconds. The other type is called “autopolymerizing”, which means it cures by itself once the two substances comprising it are mixed. They’re found equally effective in studies. The 2-component type requires less equipment but puts the dentist on a tight schedule once the two components are mixed.
Once the sealant has set, the dentist checks the patient’s bite to make sure the sealant isn’t causing any problems. The dentist may fine-tune the bite by a very quick stroke of the drill to shave down sealant where it’s too thick.
That’s it, the tooth is good to go. With a cooperative patient, the whole process takes 5-10 minutes per tooth.
GO OR NO-GO?
At a cost of $30-50 per tooth, the cost-benefit ratio of sealant relative to treating caries is obvious. Sealants typically last 5-10 years, and can be renewed or replaced.
Dental sealants come in clear, white, or various tints. The white and tinted sealants provide better visibility for the dentist’s regular inspections. Clear sealant allows the dentist to see what’s going on under it, which may be preferable where there are concerns about decay finding a way around the sealant barrier.
Downside? Not much.
From time to time concerns have been raised about the presence of the chemical BPA in dental sealants. In fact, many manufacturers have completely eliminated BPA from their dental products, and those who continue to use it have reduced the already-minuscule concentrations by as much as 50%. In any case, the American Dental Association was always on top of this and due to the tiny quantities involved, found no basis for health concerns.
Another issue that’s occasionally voiced is the prospect of existing decay being overlooked and sealed into the tooth where it would do its dirty work out of sight, with possibly devastating consequences for the interior of the tooth. This possibility is, in fact, minimized by the action of the etching gel killing bacteria it comes into contact with, and by the sealant blocking new bacteria from colonizing the treated surface.
Any concerns are legitimate concerns and should be satisfactorily addressed by the dentist before going forward with dental sealants. It’s a personal and parental decision. Weighing the costs, benefits, and risks of treatment vs. no treatment is well worth your time and attention.