Despite the continuous effort to prevent and treat dental caries, it continues to be one of the most common chronic diseases in both children and adults. Prevention and minimally intervention treatment by early detection of the lesion are becoming the new philosophy in managing dental caries. The prevalence of pit and fissure caries was found to be 90% of all dental caries in permanent molars. Moreover, the risk of caries development is higher soon after the tooth had erupted.

The purpose of the current study is; to evaluate the effectiveness of a resin-modified glass ionmer cement (Vanish XT) varnish in the prevention of occlusal caries and compare it to a fluoride varnish in newly erupted first permanent molars.

material and method: The sample will comprise of 84 bilateral pairs of newly erupted first permanent molars in children with age of 6-9 years.This sample will be randomly selected after patient's screening from pediatric dentistry clinics at King Abdul-Aziz University Dental Hospital, Jeddah, Saudi Arabia. Informed written consent will be obtained from the parents prior to sampling.

Healthy children with all four first permanent molar will be included in the study. Children must have at least one pair of contralateral newly erupted first permanent molars free from caries. Teeth with deep pits and fissures free of caries, restorations, sealants, fracture, hypoplasia, or cracks will be included in the study.

The children who met the inclusion criteria will be enrolled in the trial after a signed consent form is obtained. Pairs of maxillary or mandibular first molars will be included so that one side will be randomly assigned to study group and the contralateral side to control group.

Study group: This group will consist of 84 first permanent molars. These molars will be sealed using light curing resin-modified glass ionomer varnish (ClinproTM XT Vanish, 3M ESPE, Dental Products, St. Paul, MN, USA)

Control group: This group will consist of 84 first permanent molars. These molars will receive 5% Sodium Fluoride (NaF) with Tri-Calcium Phosphate topical varnish (Vanish White Varnish, 3M ESPE, Dental Products, St. Paul, MN, USA). These molars will serve as a control group.

The clinical examination will be assessing the caries lesions at baseline and 3,6, 12, and 18 months by the trained and calibrated dentists' according to ICDAS II criteria (International Caries Detection and Assessment System). Teeth with deep pits and fissures, which scored 0 will be included in this study.

In addition, once the clinical examination is done, bitewing radiographs will be taken for each child on the first visit to diagnose caries at the baseline.

A child structured questionnaire to be completed by interviewing the parents (adopted from WHO Oral Health Questionnaire for Children) concerning the dental history of the child and oral hygiene habits will be given at the baseline and at each recall visit.

Inclusion Criteria:

• Healthy children having no history of any systemic condition.
• Children must have all four first permanent molar.
• Children must have at least one pair of contralateral newly erupted first permanent molars free from caries.
• Teeth with deep pits and fissures (at high risk for caries).
• These molars should be free of caries, restorations, sealants, fracture, hypoplasia, or cracks.
• High caries risk children.

Exclusion Criteria:

• Children whom their parents refused to sign the consent form.
• Children older than 9 years old.
• Medically compromised children.
• Children having discolored grooves, restored, caries, or hypoplastic first permanent molars.
• Children having proximal caries in first permanent molars.
• Children whose antagonist teeth were extracted or not erupted.
• Children with a known acrylate allergy.
• Uncooperative children.

Triple blinding. Because of the nature of the material, the investigator who will apply the material to the occlusal surfaces will not be blinded to the group allocation. However, the investigators who will perform the clinical visual examination and the radiographic examination will be blinded to which group the teeth they are evaluating belongs. In addition, the statistician will be blinded.