Eruption of the first permanent molar is the earliest in our oral cavity, leading to a high occurrence of dental caries in its pits and fissures. Early prevention of pit and fissure caries in this tooth is therefore of great importance for the preservation of a healthy dentition in one's life long time.

It has been shown that sealing the occlusal surface with pit and fissure sealant is a highly effective method to prevent pit and fissure caries. It has also been shown that the performance of sealing pits and fissures by glass ionomer materia l (the high viscosity, classification type 2 GIC material) using finger press method used in the atraumatic restoration method is as significant as that of using the traditional resin sealant material and technique.

The purpose of this study is to evaluate the long-term cost-effectiveness performance of the two sealing materials in the prevention of pits and fissures caries in young permanent molars of schoolchildren in a dental public health program to be held in primary schools. The findings will provide valuable information for decision making on the election of proper material and method for use in dental public program, especially for child population in the rural or social-economically deprived areas.

Primary school children will be recruited and cluster randomized into three groups. Baseline dental check-up will be conducted to all the recruited children and dental status will be recorded. Placement of resin sealant or sealant using the glass ionomer material to the eligible permanent first molars or providing of oral health education will be interventions to the three groups respecively according to the group allocation. All the interventions will be provided only once in this study, and the children will be followed for at least 24 months at an six month interval to motor the dental caries of the included permanent first molars. Cost-effectiveness of placement of resin sealant and glass ionomer sealant will be evaluated and reported.

Inclusion Criteria:

• generally healthy grade 1-2 school children
• with written parental consent
• with at least 1 sound and fully erupted permanent first molar

Exclusion Criteria:

• Can not cooperate with the treatment
• Can not obtain the child's parental consent