Commentary

Fissure sealants are commonly used for preventing occlusal caries in permanent molars: the methods for and outcomes of sealing teeth with a resin-based sealant are well-established.1 Use of glass-ionomer-based sealants is less common and there is evidence indicating that retention rates and caries-preventive efficacy of these materials are far inferior to resin-based sealants.2, 3 It is unfortunate therefore that the authors chose to compare a resin-modified sealant with a conventional glass-ionomer. It would have been more appropriate to use the gold standard, a resin-based sealant, as the control. Table 1

Table 1 Retention rates and occlusal caries incidence.
Full size table

There are instances where glass-ionomer sealants are indicated, eg, in the field, where dental equipment is not available, or in patients who cannot co-operate sufficiently for a resin-based sealant to be used. These issues were not addressed in this paper.

The main aim was clearly focused and a RCT design was used with a control group (no treatment) and experimental group (conventional and resin-modified glass-ionomer, split mouth design). No mention was made of whether or not subjects or assessors were blinded, although in a study of this nature, where the placebo group has no treatment, this is difficult. Examiners were calibrated for variation, kappa values indicating that there was good agreement between examiners and between the assessments made over time by each examiner. The power calculation was not described, however. The number of dropouts at each examination interval was described but the reasons for lack of attendance were not given. No measures of variability (such as median or interquartile range) were reported. In addition, actual P values were not reported for differences in caries incidence (P=0.05 was used) although they were given for retention rates. This suggests that the statistical significance for differences in caries incidence may have been borderline.

Retention rates were poor, although the resin-modified sealant (Vitremer) did have significantly higher retention rates than the conventional glass-ionomer (Ketac-Bond) (P<0.001). Neither compare favourably to values reported for resin-based sealants in other studies, where retention rates in excess of 90% are common.2, 3 Use of glass-ionomer sealants resulted in a significant reduction (P=0.05) in caries incidence compared to the control group. Results from other studies, however, suggest that the reduction in caries incidence would have been greater if a resin-based sealant had been used.2, 3 There were no significant differences in caries preventive efficacy between the two types of glass-ionomer.

Practice points

  • Resin-modified glass-ionomer (Vitremer) appears to have a better retention rate than conventional glass-ionomer (Ketac Bond) when used as a fissure sealant but there was no significant difference between the two in caries prevention.

  • Glass ionomer sealant has a caries-preventive effect.

  • A conventional resin-based sealant remains the material of choice.