This study was conducted on 44 (19 girls and 25 boys) patients presenting 132 permanent first molars, who applied for oral examination to Adnan Menderes University Faculty of Dentistry Department of Pediatric Dentistry. The patients involved in the study were aged between 7-11 years who had fully erupted permanent first molars, which were suitable for non-invasive fissure sealant application (narrow, deep fissures).

The permanent first molar teeth were cleaned using a polishing brush and pumice and isolated with cotton rolls. Caries status was assessed using DIAGNOdent pen (DIAGNOdent pen 2190, KaVo, Biberach, Germany) at the occlusal and proximal sites. Teeth having DIAGNOdent readings of 12 or less at the occlusal site and 7 or less at the proximal site were included in the study. Then, the teeth were divided into three groups. The first group (Grup A) of teeth were etched with phosphoric acid, the second group of teeth (Group L) were etched with Er:YAG laser and the third group of teeth (Group A+L) were etched with both Er:YAG laser and phosphoric acid. The patients were recalled for follow up examination at the 3rd, 6th and 9th months. The teeth were assessed using mouth mirror and explorer regarding new caries formation and retention of the fissure sealants. The obtained data were analyzed using SPSS 24.0 (SPSS 24.0 for Windows, SPSS Inc., Chicago, IL, USA).

Inclusion Criteria:

• Patients who participated in this study had good general health and oral hygiene.
• Fully erupted permanent first molar teeth with deep, narrow fissures
• Teeth with no detectable occlusal and proximal caries

Exclusion Criteria:

• Hypomineralized areas such as fluorosis, molar incisor hypomineralization
• Allergy to resins, who were not willing to participate in the study.
• Teeth with hypomineralized areas such as fluorosis,
• Teeth with molar incisor hypomineralization

The results will be shared with other researchers.