The aim of this study is to evaluate and compare the clinical effectiveness of ICON resin Infiltration versus conventional sealant and the microleakage and penetration depth of the two sealant materials.

Using the resin infiltration technique as a different approach for sealing pits and fissures creates a diffusion barrier as resin infiltrate tends to inhibit enamel pores that serve as diffusion channels for acids and dissolved minerals within the lesion body. A low-viscosity resin that can penetrate into caries lesions, which is referred to as resin infiltration technique. The mechanisms associated with this method depend on the infiltration of subsurface lesions with low-viscosity light-curing resins after eroding the highly mineralized surface layer and increasing penetration depth. This method is believed to overcome the limitations of sealant applications and is considered to be a better alternative for the treatment of initial caries lesions.

Inclusion Criteria:

1. Age of the children from 6 to 8 years.
2. Healthy children free from any systemic disease.
3. Show bilaterally sound fully erupted lower first permanent molars with deep narrow central fissures and supplemental grooves.
4. The eruption time of these molars should not exceed 3 years.
5. No sign of pain or active periodontal disease in the selected teeth.

Exclusion Criteria:

1. Children with fillings or sealants in the selected teeth.
2. Children with clinical evidence of caries in the selected teeth either white spot lesions or cavities.
3. Children with an allergy to any drug, such as resin restorative material.
4. Children with Extremely poor oral hygiene.
5. Hypoplastic teeth.
6. Children with bruxism.

For the application of ICON, The cleaned fissure was etched using an Icon-Etch in its special syringe for 2 minutes. Then the tooth was rinsed off using water for at least 30 seconds and dried with oil-free and water-free air. Followed by application of the Icon-Dry applied into the fissure and let sit for 30 seconds. The excess of the Icon-Dry was removed and dried with oil-free and water-free air.an ample amount of Icon-Infiltrate is applied into the fissure away from the direct light of the dental unit and let sit for 3 minutes. After excess removal, it will be cured with a light source* according to the manufacturer's instructions. A second layer of the Icon Infiltrate was applied and cured in the same way.