Open-mouth posture and maxillary arch width in young children: a three-year evaluation.

A large biracial sample of children were assessed for open mouth posture and maxillary arch width once a year for 3 years. Analyses revealed that although the youngsters exhibited open-mouth posture at high levels, over time, there was a significant decrease in this behavior. Racial and gender differences, as well as a race-by-time interaction, were also evidenced. The children displayed a significant increase in maxillary arch width across time, with gender and racial differences seen in this growth pattern. Finally, when the youngsters were classified as exhibiting primarily open-mouth or closed-mouth posture, it was observed that children with open-mouth posture displayed a significantly slower pattern of maxillary growth compared with children who display anterior lip seal posture. The implications of the findings were discussed.