Midline diastemas: closure and stability.

In growing patients, midline diastemas often appear during a transitory stage of development, and then close spontaneously. Occasionally a local cause must be identified and eliminated before the diastema can be closed orthodontically with a stable result. In nongrowing adult patients, the situation is quite different. The following case report shows two patients with similar malocclusions who received similar treatment but whose results were quite different. The patients had relatively rare mandibular midline diastemas in which the causative factor was tongue resting pressure. The report concludes with a description of two posttreatment alternatives to avoid relapse.