Sealants for preventing dental decay in the permanent teeth

Although children and adolescents of today have more healthy teeth than in the past, tooth decay (dental caries) is still a problem in some individuals and populations, and in fact affects a large number of people around the world. The majority of decay in children and adolescents is concentrated on the biting surfaces of back teeth. The preventive treatment options for tooth decay include tooth brushing, fluoride supplements (for example chewing gums) and topical fluoride applications and dental sealants which are applied at dental clinics.

Because prevention of dental caries is important from a public health point of view the Cochrane Oral Health Group undertook a review of existing research into whether or not the use of dental sealants prevents dental decay. Thirty-four trials were included in this review, children and young people taking part were aged from 5 to 16 years and represented the general population.

The search of studies was updated on 1st November 2012.

Dental sealants are intended to prevent the growth of bacteria that promote tooth decay in grooves of back teeth. Sealants are applied onto these grooves by a dentist or by another member of the dental care team. There are several sealant materials available, the main types in use are resin-based sealants and glass ionomer cements.

This review summarised information from 34 separate studies involving 6529 young people to whom a variety of dental sealants were used for preventing caries and found evidence that applying sealants to the biting surfaces of the back teeth reduces caries when compared to not using sealants.

Twelve of the 34 studies compared resin-based sealants to no sealants and found that children who have their back teeth covered by a sealant are less likely to have dental decay in their back teeth than children without sealant. For example, if 40% of back teeth develop decay over a 2-year period then the sealant reduces this to 6%. In another group of children where 70% of these back teeth would develop decay over a 2-year period, using sealants reduces this to 19%. These results are based on data from six studies (five of which were published in the 1970s) where the children were aged 5 to 10 years when the sealants were placed. Similar benefits for resin-based sealants were shown up to 9 years. There was no clear benefit of one type of sealant over another when they were compared with each other.

Authors' conclusions: 

The application of sealants is a recommended procedure to prevent or control caries. Sealing the occlusal surfaces of permanent molars in children and adolescents reduces caries up to 48 months when compared to no sealant, after longer follow-up the quantity and quality of the evidence is reduced. The review revealed that sealants are effective in high risk children but information on the magnitude of the benefit of sealing in other conditions is scarce. The relative effectiveness of different types of sealants has yet to be established.

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Background: 

Dental sealants were introduced in the 1960s to help prevent dental caries in the pits and fissures of mainly the occlusal tooth surfaces. Sealants act to prevent the growth of bacteria that can lead to dental decay. There is evidence to suggest that fissure sealants are effective in preventing caries in children and adolescents when compared to no sealants. Their effectiveness may be related to the caries prevalence in the population.

Objectives: 

To compare the effects of different types of fissure sealants in preventing caries in permanent teeth in children and adolescents.

Search strategy: 

We searched the Cochrane Oral Health Group's Trials Register (to 1 November 2012); the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2012, Issue 7); MEDLINE via OVID (1946 to 1 November 2012); EMBASE via OVID (1980 to 1 November 2012); SCISEARCH, CAplus, INSPEC, NTIS and PASCAL via STN Easy (to 1 September 2012); and DARE, NHS EED and HTA (via the CAIRS web interface to 29 March 2012 and thereafter via Metaxis interface to September 2012). There were no language or publication restrictions. We also searched for ongoing trials via ClinicalTrials.gov (to 23 July 2012).

Selection criteria: 

Randomised or quasi-randomised controlled trials of at least 12 months duration comparing sealants for preventing caries of occlusal or approximal surfaces of premolar or molar teeth with no sealant or different type of sealant in children and adolescents under 20 years of age.

Data collection and analysis: 

Two review authors independently screened search results, extracted data and assessed trial quality. We calculated the odds ratio (OR) for caries or no caries on occlusal surfaces of permanent molar teeth. For trials with a split-mouth design, the Becker-Balagtas odds ratio was used. For mean caries increment we used the mean difference. All measures are presented with 95% confidence intervals (CI).
The quality of the evidence was assessed using GRADE methods.
We conducted the meta-analyses using a random-effects model for those comparisons where there were more than three trials in the same comparison, otherwise the fixed-effect model was used.

Main results: 

Thirty-four trials are included in the review. Twelve trials evaluated the effects of sealant compared with no sealant (2575 participants) (one of those 12 trials stated only number of tooth pairs); 21 trials evaluated one type of sealant compared with another (3202 participants); and one trial evaluated two different types of sealant and no sealant (752 participants). Children were aged from 5 to 16 years. Trials rarely reported the background exposure to fluoride of the trial participants or the baseline caries prevalence.

- Resin-based sealant compared with no sealant: Compared to control without sealant, second or third or fourth generation resin-based sealants prevented caries in first permanent molars in children aged 5 to 10 years (at 2 years of follow-up odds ratio (OR) 0.12, 95% confidence interval (CI) 0.07 to 0.19, six trials (five published in the 1970s and one in 2012), at low risk of bias, 1259 children randomised, 1066 children evaluated, moderate quality evidence). If we were to assume that 40% of the control tooth surfaces were decayed during 2 years of follow-up (400 carious teeth per 1000), then applying a resin-based sealant will reduce the proportion of the carious surfaces to 6.25% (95% CI 3.84% to 9.63%); similarly if we were to assume that 70% of the control tooth surfaces were decayed  (700 carious teeth per 1000), then applying a resin-based sealant will reduce the proportion of the carious surfaces to 18.92% (95% CI 12.28% to 27.18%). This caries preventive effect was maintained at longer follow-up but both the quality and quantity of the evidence was reduced (e.g. at 48 to 54 months of follow-up OR 0.21, 95% CI 0.16 to 0.28, four trials (two studies at low risk of bias and two studies at high risk of bias), 482 children evaluated; risk ratio (RR) 0.24, 95% CI 0.12 to 0.45, one study at unclear risk of bias, 203 children evaluated).

- Glass ionomer sealant compared with no sealant: There is insufficient evidence to make any conclusions about whether glass ionomer sealants, prevent caries compared to no sealant at 24-month follow-up (mean difference in DFS -0.18, 95% CI -0.39 to 0.03, one trial at unclear risk of bias, 452 children randomised, 404 children evaluated, very low quality evidence).

- Sealant compared with another sealant: The relative effectiveness of different types of sealants remained inconclusive in this review.
Twenty-one trials directly compared two different sealant materials. Several different comparisons were made according to type of sealant, outcome measure and duration of follow-up. There was great variation with regard to comparisons, outcomes, time of outcomes reported and background fluoride exposure if this was reported.

Fifteen trials compared glass ionomer with resin sealants and there is insufficient evidence to make any conclusions about the superiority of either of the two materials. Although there were 15 trials the event rate was very low in many of these which restricted their contribution to the results.

Three trials compared resin-modified glass ionomer with resin sealant and reported inconsistent results.

Two small low quality trials compared polyacid-modified resin sealants with resin sealants and found no difference in caries after 2 years.

- Adverse effects: Only two trials mentioned adverse effects and stated that no adverse effects were reported by participants.

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