The purpose of this study was to determine the prevalence and severity of molar-incisor hypomineralization (MIH) by examining standard orthodontic intraoral photographs. A total of 690 patients were evaluated retrospectively for the presence or absence and extent of MIH using standardized assessment criteria. Fourteen percent of all patients examined presented with MIH on at least one tooth. There was no significant difference in the presence of MIH when compared to age, race, or gender. MIH is most commonly presented on maxillary molars and maxillary central incisors as demarcated opacities with less than one-third of the tooth affected. More severe clinical status groups were associated with higher average age and were more commonly seen in molars than incisors. At 14 percent, the prevalence is reflective of the worldwide prevalence previously determined from other studies. MIH most commonly presents in its mildest form; however, older individuals tend to present with more severe forms, indicating that it continues to cause problems as patients age. Future studies should extend to further areas to continue to ascertain the extent and severity of this condition.