Glass Ionomer, Resin Composite Sealants Each Has Its Place

Laird Harrison

March 20, 2012

March 20, 2012 — Resin-based pit-and-fissure sealants lasted longer, but glass ionomer pit-and-fissure sealants protected better against caries in a 2-year head-to-head trial published in the January-February issue of Pediatric Dentistry.

The study showed that each kind of sealant is useful in different circumstances, the study's first author, Vineet Dhar, MDS, PhD, MBA, an associate professor of pediatric dentistry at the University of Maryland in Baltimore, told Medscape Medical News.

The study also reinforced guidelines from the American Dental Association and the American Academy of Pediatric Dentistry not to mechanically prepare tooth surfaces for sealants.

"Even though mechanical preparation increased retention, it predisposed teeth to caries, so it should be done with great caution and only if indicated in a particular case," said Dr. Dhar in an email.

Although resin sealants are used on more teeth, at least in the United States, ionomer sealants are thought to be less technique-sensitive and offer the additional advantage of releasing more fluoride.

Previous studies have reported similar caries rates in teeth with the 2 types of sealant: about 5% of surfaces 2 years after sealing. Dr. Dhar and colleagues set out to compare the 2 types in a head-to-head trial.

The researchers enrolled 25 children aged 6 to 10 years in rural areas of Udaipur, India. The children's families had annual family incomes of less than $1500.

All of the children had 4 erupted, noncarious permanent first molars, and researchers randomly assigned each of these 100 teeth into 1 of 4 groups:

  • A group in which the teeth were mechanically prepared and GC Fuji Ionomer VII glass ionomer sealants (GC Corp) were placed on them.

  • A group in which the teeth were mechanically prepared and Clinpro pink resin-based sealants (3M ESPE) were placed on them.

  • A group in which the teeth were not mechanically prepared and the ionomer sealants were placed on them.

  • A group in which the teeth were not mechanically prepared and the resin sealants were placed on them.

The mechanical preparation consisted of widening and deepening the fissures with a one-quarter round bur in a slow-speed hand piece.

None of the teeth sealed with glass ionomer sealants, with or without tooth preparation, lost all their sealant after 6 months. However after 2 years, total loss of ionomer sealants with tooth preparation was 60%. The total loss rate at 2 years for ionomer sealants without preparation was 100%.

In comparison, 28% of the teeth sealed with resin without preparation showed total loss of the sealant at 6 months. Total loss of sealant in these teeth after 2 years was 80%.

In the teeth sealed with resin-based sealant after tooth preparation, none lost all their sealant at 6 months, but 32% lost all their sealant after 2 years.

The superior ability of prepared teeth to retain their sealants when compared with unprepared teeth was statistically significant (P < .001). The superior retention of resin sealants when compared with glass ionomers was also statistically significant (P < .001).

Retention was also statistically better in prepared teeth sealed with ionomer vs unprepared teeth sealed with resin.

No secondary caries emerged in any of the teeth for the first 6 months, but after 2 years, teeth sealed with glass ionomer–based sealants with preparation showed a 4% incidence of caries. Ionomer-sealed teeth without preparation showed an 8% incidence of caries, which is a highly significant difference (P < .001).

Resin-sealed teeth with tooth preparation had a 16% incidence of caries, whereas resin-sealed teeth without tooth preparation showed a 12% incidence, which is also a statistically significant difference (P < .01).

The difference in caries incidence between ionomer-sealed teeth and resin-sealed teeth was significant as well (P < .01).

One factor that may have affected these findings was poor oral hygiene among the children in the study, the authors note.

Although the difference in caries incidence was significant, the overall rate was low, the researchers write. They speculate that the low overall incidence could be attributed to some sealant adhering in the pits and fissures, even when most of it was lost.

They add that the superior caries rates among the ionomer-sealed teeth might be a result of the fluoride released by this material.

To better determine the caries risk in teeth sealed with the 2 types of sealant, Dr. Dhar said he would like to conduct a longer-term study.

Asked to comment on the study, Joel Berg, DDS, president elect of the American Academy of Pediatric Dentistry and chair of pediatric dentistry at the University of Washington in Seattle, told Medscape Medical News that the study might call more dentists' attention to ionomer sealants.

One advantage of the ionomer sealants is that they can be applied in mouths with some moisture, he said. That makes them much less technique-sensitive, which can be a key an advantage in newly erupting teeth or in patients who have difficult cooperating, excess saliva, or a gag reflex.

However, resin sealants' superior retention makes them preferable in most instances, he said.

"If you can effectively isolate and place a resin sealant, you should," said Dr. Berg, who was not associated with the study. "But if you can't place a resin sealant, a glass ionomer sealant will do a lot of good."

As for tooth preparation, this should only be done to remove decay, he said.

Dr. Berg and Dr. Dhar have disclosed no relevant financial relationships.

Pediatr Dent. 2012;34:46-50. Abstract

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