Dental Sealants: The basics.
- What are they? / How do they work? / Which teeth? What age? / How long do they last?
Tooth Sealants -
a) What are they?
A dental sealant is a thin plastic coating (clear or white) that's bonded into the pits and grooves of a tooth.
They're most frequently placed on the chewing surface of teeth (where most of a tooth's grooves lie). But they can also extend onto their cheek or tongue sides too (either as a continuous or separate piece) depending on what additional pits and fissures are found there.
There's nothing new about the use of sealants. Dentists have been placing them since the late 1960's.
b) Why are they needed?
Sealants help to protect teeth from the formation of tooth decay.
The general problem.
As compared to smooth surfaces, a tooth's pits and fissures tend to trap debris (dental plaque, food particles, etc...). And when they do, it places them at greater risk for cavity formation.
[It's been estimated that 90% of tooth decay in school children occurs in pits and fissures. (Kaste 1996)]
A sealant fills in these grooves so debris can't accumulate. (See diagrams below.)
As compared to the alternative (allowing a cavity to form and then placing a filling), this procedure is a very simple and cost-effective measure.
c) Who should get them?
Most sealants are placed on the teeth of children (see below for details). However, any person who has a tooth that could benefit from this type of protection, no matter what their age, can and should receive one.
d) When should they be applied?
Sealants are considered a preventive measure, not a corrective one (like placing a filling).
- The most predictable sealants are those that are placed before any sign of a cavity has had a chance to form.
For this reason, once a tooth has been identified as a candidate, it's a good idea to have it sealed as soon as is reasonably convenient.
- Even if vague signs of cavity formation have started to appear ("incipient" decay), a dentist may determine that it's still acceptable that a sealant can be placed. This simply needs to be determined on a case-by-case basis.
One study (Heller 1995) evaluated teeth with incipient decay over a 5 year period. Only 11% of the teeth that received sealants developed a cavity, whereas 52% of the group that received no treatment did.
How do dental sealants work?
In a nutshell, a sealant creates a smoother tooth surface. One that's easier to clean and therefore more resistant to the formation of decay.
Cavities are caused by bacteria that live in dental plaque (the white film that forms on teeth). Tooth brushing helps to prevent decay by scrubbing this film away. (More information - How do cavities form?)
Grooves too narrow for toothbrush bristles to clean should be sealed.
The problem is, deep tooth grooves can be hard to clean.
Some teeth, especially molars, have grooves (pits and fissures) on their chewing surface and sides that are narrow and deep.
And in these cases, when the person brushes their teeth, some of the dental plaque that has accumulated on them is left behind.
That's because the individual bristles of their toothbrush are too large to reach into the depths of their tooth's pits and fissures (as illustrated in our graphic). And because some plaque is left behind, the tooth remains at risk for cavity formation.
Dental sealant is bonded into the grooves of a tooth.
b) How a tooth sealant solves this problem.
By bonding dental sealant into the grooves of a tooth, a dentist can make a tooth's surface smoother.
As a result, there are no longer any locations where the bristles of a toothbrush can't reach and clean. The tooth is now at less risk for developing a cavity.
Sealants can help to protect vulnerable tooth locations.
c) A side benefit of sealing a tooth.
Another difficulty associated with teeth that have deep pits and fissures is the thickness of the enamel that lies at their base. It may be comparatively thin (see our graphic).
That means not only does the groove make it more likely that decay may form but if it does it will have an easier time of penetrating into the interior of the tooth. Placing a dental sealant in time can prevent this scenario.
d) Fluoride release.
Some sealants are formulated with fluoride. Its release, right at a tooth's surface, can help to lower its chances for decay.
Should sealants always be placed?
Not all teeth require the protection that dental sealants can provide. After an examination, your dentist can report to you what they feel is indicated.
Debris and stain accumulation in narrow tooth grooves.
Here's what a dentist looks for.
- Any tooth that has pits and fissures that tend to accumulate debris is a candidate for a sealant.
It literally is the shape of the tooth's grooves that the dentist evaluates. Teeth that have deep and narrow ones will have a more urgent need than teeth whose grooves are naturally shallow and rounded.
- "Back" teeth typically have the most pronounced grooves and therefore are the most-sealed. But any type of tooth might have some type of surface irregularity that makes sealing it a good idea.
- Beyond just tooth anatomy a dentist will evaluate other factors that may amplify the person's need for sealants.
This will include: the amount of dental plaque they find present, eating habits/types of foods eaten, the amount of decay the patient has experienced in the past, and the patient's current exposure to an appropriate amount of fluoride.
- As explained above, any tooth that has already developed incipient decay is certainly a candidate for a sealant. Placing one may avoid the need for a filling later on.
At what age should sealants be placed? On which teeth?
While a dental sealant can be placed on any tooth at any age, most are placed on the teeth of children. For this group, certain rules of thumb apply.
- A tooth must be kept dry during sealant application. That means the portion of the tooth receiving treatment must be erupted through its surrounding gum tissue enough that this is possible.
- The patient must be able to provide at least some degree of cooperation.
The specific age at which this combination of events occurs will vary from tooth to tooth, and child to child. It typically rests upon the dentist to make a recommendation as to when any specific tooth can and should be sealed.
- Permanent 1st molars (6-year molars) - These teeth usually come in between ages 5 to 7 years. At this age, most children are cooperative enough to allow this procedure to be performed, so as soon as the molar has penetrated its gum line far enough a sealant can be placed.
Common recommendations: 1st molars are probably the most frequently sealed teeth and it's easy to understand why. While they are intended to serve a child for their entire lifetime, they come in at an age when eating and brushing habits are typically lax. In fact, molars are the type of tooth that's the most likely to experience decay.
Most dentists probably prefer to error in favor of recommending sealants for 1st molars, as opposed to not. A properly placed and maintained dental sealant has no potential to cause harm, whereas not placing one may have consequences.
- Permanent 2nd molars (12-year molars) - These teeth typically come in between ages 11 to 14 years. At this age, there should be little concern about patient cooperation, so it's just a matter of waiting until the tooth has erupted far enough through the gums to apply the sealant.
Common recommendations: As compared to age 6, at age 12 years the dentist will have a clearer picture of their patient's risk for cavities.
For children who have comparatively shallow tooth grooves, display good eating and oral homecare habits, have no history of decay and dental costs are a concern for the family, a dentist might not feel strongly about the need for sealant placement on the child's 2nd molars.
For families where finances are not a concern, since statistically molars are the teeth most likely to experience decay, protecting one from square one might be something they're eager to do.
- Other permanent teeth. - A recommendation for sealant placement on other types of permanent teeth is typically made on a case-by-case basis.
Premolars (bicuspids) - These teeth may very well display the same deep groove anatomy of their neighboring molars. If so, sealants should be placed. After molars, bicuspids are the teeth most likely to receive a sealant.
Incisors - While relatively uncommon, front teeth may need the protection of a sealant. For example, upper incisors are well known for having a pit on their backside that is often deep and accumulates plaque.
- Baby teeth (deciduous teeth) - While there is no question that baby teeth are important (they hold space for their permanent replacements), recommendations for protecting them tends to vary.
Besides just pit and groove depth, a number of other issues must be considered too. This includes: available patient cooperation, how long before the tooth will fall out on its own, etc... You'll simply need to seek your dentist's advice on this matter.
- Teeth of adult patients - Any permanent tooth can be sealed, at any time.
Common recommendations: A need for this type of protection for adults not all that common.
In most cases, one would expect that a tooth whose deep pits and fissures place it at great risk for cavity formation would have already developed decay by the time adulthood is reached. Of course, there can always be exceptions. This issue simply needs to be determined on a case-by-case basis.
How long do dental sealants last?
A dentist would probably consider any sealant that remained intact for 3 to 5 years to be a success. One study's review of dental literature (Feigal, 1998) estimated a sealant loss rate (including partial loss) on the order of 5 to 10% per year.
They can, however, last much longer than that. 10 years might be considered the upper limit for one, although it's somewhat common that a dentist will see sealants that were placed during childhood still intact on an adult patient's teeth.
Any sealants that require repair sooner than 3 to 5 years should not necessarily be considered failures. Any length of time a sealant remains in place is a time period during which its tooth is protected.
a) Sealant maintenance is critical.
A dental sealant can only provide protection if it's fully intact. In fact, one study (Mertz-Fairhurst, 1984) determined that the decay rate for molars with partially retained sealants was essentially the same as those that never received one.
- If you notice that any portion, or even all, of a sealant has come off, you should let your dentist know.
- During each of your regular dental checkups, your dentist will evaluate the integrity of your sealants and let you know if any of them require repair.
b) A second try might be more successful.
One reason why a sealant might come off is because the dentist wasn't able to keep the tooth dry during its placement. This can certainly be the case where a child patient has been uncooperative.
As the child becomes older and more mature, even by several months or a year, it's quite possible that a second attempt to seal the tooth will be more successful.
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