This clinical study aimed to compare the effectiveness of two minimally invasive approaches for masking molar-incisor hypomineralization (MIH) opacities and to evaluate esthetic perceptions of children and their parents. Participants with MIH-affected incisors received either resin infiltration or etch-bleach-seal treatment. Esthetic outcomes and satisfaction levels were assessed using standardized scales.

Molar-incisor hypomineralization (MIH) is a qualitative enamel defect that often leads to esthetic concerns, particularly in anterior teeth. Minimally invasive treatment approaches such as resin infiltration and etch-bleach-seal techniques have been proposed to improve the appearance of MIH opacities.

This study aimed to compare the effectiveness of these two approaches in masking MIH opacities in permanent incisors and to evaluate esthetic perceptions from both children and their parents. Esthetic perceptions related to dental appearance were evaluated using the ''Child's and Parent's Questionnaire about Teeth Appearance''. The color masking effectiveness of resin infiltration and the etch-bleach-seal (EBS) technique on MIH-related anterior enamel opacities were evaluated using a spectrophotometer (VITA Easyshade® V, Sackingen, Germany).

The findings are expected to contribute to evidence-based decision-making for minimally invasive esthetic management of MIH.

Inclusion Criteria:

• Age between 8 and 10 years,
• Diagnosis of MIH according to the European Academy of Paediatric Dentistry (EAPD) criteria [19], with at least one permanent incisor exhibiting well-demarcated white-cream and/or yellow-brown enamel opacities causing esthetic concern to the child and/or parents,
• Absence of urgent dental treatment needs, with completed treatment of posterior teeth,
• Ability of both children and parents to read and understand Turkish.

Exclusion Criteria:

• Presence of urgent dental treatment or requirement for restorative treatment of MIH affected permanent first molars during the study period,
• Presence of dental or facial anomalies other than MIH (e.g. hypodontia, cleft lip and/or palate),
• Presence of dental caries, crown fractures, or extrinsic/intrinsic tooth discolorations that could compromise esthetic perception,
• Presence of other developmental enamel defects (e.g. enamel hypoplasia, amelogenesis imperfecta, fluorosis, or hypoplasia related to previous dental trauma),
• Previous restorative treatment, resin infiltration, microabrasion, and/or tooth whitening on the affected incisors,
• Children and/or parents who were unlikely to attend follow-up visits or were unable to read and understand Turkish.

Individual participant data will not be shared due to ethical and privacy considerations, as the study involves pediatric participants. Data are available from the corresponding author on reasonable request and with appropriate ethical approval.

Due to the nature of the clinical procedures, blinding of the operator was not possible. To minimize potential assessment bias, the evaluation of esthetic perception questionnaires completed by children and their parents were performed by another investigator who was blinded group allocation. In addition, children and their parents were not informed about the specific treatment technique applied and informed only that a minimally invasive esthetic procedure would be performed.