The prevalence of molar incisor hypomineralization is relatively high. It has been reported that MIH-affected children experience a wide range of negative impacts because of having visible enamel opacities on their incisors whether these teeth show post eruptive breakdown or not. The management of MIH is challenging with a broad spectrum of treatment modalities being available. However, there are no clear guidelines available to aid in clinical decision making. Possible treatment options for anterior teeth with MIH include: Microabrasion, resin infiltration, tooth bleaching, etch-bleach and seal technique and composite restorations or veneers. It is believed that these methods could be used alone or in a combination of methods to achieve better aesthetic results.

For MIH affected-incisors microabrasion and resin infiltration are acceptable treatment options which could be used alone or in a combination. Accordingly, the aim of this study is to compare the clinical outcomes of using resin infiltration either alone or combined with microabrasion for the management of MIH affected incisors.

The study will be conducted on a dental unit in postgraduate clinic of Pediatric Dentistry and Dental Public Health Department, Faculty of Dentistry, Cairo University, Egypt.The primary hypothesis of this study is that a resin infiltration and microabrasion combined treatment will result in better clinical outcomes than using resin infiltration alone. All treatment procedures will be carried out by the principal investigator.

36 patients will be included in the study. The teeth will be randomized into two groups according to the intervention. The study involves two types of interventions:

Group 1 (resin infiltration):

The treatment will follow the manufacturer's instructions (Icon, DMG, Hamburg, Germany). The procedure involves the application of Icon-Etch, Icon-Dry as well as Icon-Infiltrant. Followed by removal of excess and then polishing of the treated surfaces.

Group 2 (Micro-abrasion followed by resin infiltration):

The Micro-abrasion agent (Opalustre, Ultradent, South Jordan, UT, USA) will be applied to the tooth for 60 seconds using a standard rubber cup attached to a low speed hand piece followed by rinsing the tooth surface with water for 20 seconds. This procedure will be repeated up to 5 times.

Resin infiltration will then be carried out as discussed before.

Vita Easyshade Advance® spectrophotometer (Vita Zahnfabrik, Sackingen, Germany) will be used to evaluate the masking color of the teeth selected in the study.

Measurements will be taken before, immediately after, 1 month, 3 months, 6 months and 12 months after treatment.

A standardized Photograph will be taken at 5 different times (before treatment, immediately afterwards, one month, 6 months and 12 months after treatment with the exact same camera and conditions. The images collected will be analyzed and evaluated by 2 different dentists.

Inclusion Criteria:

1. Cooperative children aged between 7-16 years old
2. Children with MIH having enamel opacity involving at least one permanent incisor
3. MIH- affected incisors which did not receive any previous treatment
4. 1/3 of the crown should be visible in the oral cavity
5. Lesions size should be more than 1mm
6. Healthy children

Exclusion Criteria:

1. Children with systemic diseases, allergies or any dental or facial anomaly other than MIH
2. Children aged < 7 or > 16 years old
3. Uncooperative children
4. MIH patients without the affection of the incisors or with compromised incisor esthetics due to tooth surface loss, traumatic dental injury or caries
5. MIH incisors which already received any kind of treatment
6. Lesions which are smaller than 1mm in size

Selection bias: will be overcome by randomization and allocation concealment. Performance bias: will be overcome by standardized method of application by single operator.

Detection bias: will be overcome by blinding of the outcome assessor. Reporting bias: All the outcomes will be reported and published.