The current study compares the efficacy of glass ionomer fissure sealant versus topical application of 5% sodium fluoride varnish in prevention of occlusal caries among preschool children.

Topical fluoride varnish (TFV) with 5% sodium fluoride in its content has proven effective in preventing caries among children and adolescents. Its reduction in DMFT is well supported by Cochrane reviews and clinical trials. However, its effect in preventing pit and fissure caries in primary dentition has not been assessed.

Pit and fissure sealants have been a recommended procedure in preventing caries development in permanent molars. Multiple systematic reviews and clinical trials have concluded that fissure sealants are significantly more effective than topical fluoride varnishes in preventing occlusal caries in permanent molars. However, a recent Cochrane review suggested that there was still insufficient evidence to determine superiority of resin or glass ionomer fissure sealants over topical fluoride varnishes for occlusal caries prevention, due to the lack of reliable results and low quality of evidence.

Also, most studies were conducted on permanent first molars among school children, whom cooperation and moisture control can be easily achieved. However, application of fissure sealants, especially resin-based sealant, in very young children can be a technique-sensitive procedure. Compared with a mean treatment time of less than 3 minutes for varnish application, application of resin-based sealants required over 15 minutes. Moisture control is also of paramount importance for the retention and success of resin-based sealants, which may be difficult among young preschool children.

Glass-ionomer sealants can chemically bond to enamel and are more tolerable to inadequate moisture control. As its application requires less clinical steps, glass-ionomer sealant is comparatively more acceptable to younger patients and can be used in outreach settings with a large number of participants. The fluoride releasing ability is also beneficial in preventing caries especially at adjacent tooth surfaces. However, its retention rate is significantly lower than that of resin-based sealants, its success rate in preventing fissure caries in very young patients is still unknown.

Inclusion Criteria:

Generally healthy children aged between 3-5 years with no remarkable medical history.

Exclusion Criteria:

1. Children with the presence of caries of ICDAS code 3, 4, 5, or 6 on other primary teeth.
2. Children who had received professional fluoride application in the past 6 months.
3. Children with serious systemic disease or taking long term medication.
4. Children who are uncooperative or refuse the treatment.
5. Second primary molars that are (i) with caries in dentin indicated by ICDAS code 4, 5 or 6; (ii) partially erupted; (iii) with fillings and/or sealants; and (iv) hypoplastic or hypomineralized.

Blinding is not possible as pink glass ionomer sealants will be placed on the primary molars of one of the groups.