The aim of this study is to assess the prevalence of molar incisor hypo mineralization among children who have been treated with asthmatic drugs during the first three years of life.

The term Molar incisor hypo mineralization (MIH) was first introduced in 2001 as a developmental disorder of enamel characterized by hypo mineralization -of systemic origin - affecting the enamel of first permanent molars (PFM) ,frequently associated with affected permanent incisors.

The prevalence of MIH varies widely, ranging from 2.4 % to 40.2% in different populations. This wide variation may be due to differences in diagnostic criteria and methodologies used by the authors. Concerning the etiology of MIH it is mostly related to pre natal, perinatal, and post natal illness.

Asthma and asthmatic drugs have been proposed to be one of the etiological factors of MIH,Internationally, the mean prevalence of pediatric asthma is 10%.

Inclusion Criteria:

1. Children from 8 to 12 years old with fully erupted first permanent molars and permanent incisors.
2. Children who were patients of the Pediatric Pulmonary Clinic and had used asthma drugs (oral and inhaled bronchodilators or corticosteroids) during their first three years of life.

Exclusion Criteria:

1. Children with any chronic disease
2. Children with unerupted or partially erupted first permanent molars.
3. Children using a fixed orthodontic appliance
4. Children having extensive carious lesions that might mask dental enamel defects.

children aged from 8 to 12 years old with fully erupted first permanent molar and permanent incisors, who have been treated with any type of asthmatic drugs during their first three years of life.