Changes in interdental papillae heights following alignment of anterior teeth

BACKGROUND: Orthodontic alignment of overlapped incisors can reduce the apparent heights of the interdental papillae leading to unsightly dark triangles or open gingival embrasures. AIM: To determine if certain pretreatment contact point relationships between the maxillary anterior teeth were accompanied by changes in the heights of the interdental papillae after orthodontic alignment. METHODS: Pre- and post-treatment intra-oral 35 mm slides, lateral cephalometric radiographs and study casts of 143 patients (60 males, 83 females) between 13 and 16 years of age were used. The patients had diastamata closed, imbricated teeth aligned and palatally or labially placed teeth repositioned. A sample of 25 patients (12 males, 13 females) between 13 and 16 years of age who had well-aligned anterior teeth at the start of treatment acted as a control group. All patients were treated for approximately 18 months. The clinical crowns of the maxillary incisors and the heights of the interdental papilla between the incisors were measured on projected images of the slides. The percentage increases or reductions in the heights of the interdental papillae were compared. RESULTS: The heights of the interdental papillae increased following palatal movement of labially placed (p < 0.05) or imbricated (p < 0.05) incisors and the intrusion of one incisor relative to an adjacent incisor (p < 0.01). The heights of the interdental papillae reduced following labial movement of an imbricated (p < 0.05) or palatally placed (p < 0.05) incisor or closure of a diastema (p < 0.01). Before treatment the midline papillae in the diastema subgroup were of similar length to the midline papillae in the control group, but after treatment they were markedly shorter. The interdental papillae associated with crowded or imbricated incisors were shorter than the interdental papillae in the control group before and after treatment. CONCLUSIONS: Dark triangles are less likely to develop following palatal movement of labially placed or imbricated teeth and the intrusion of one tooth relative to another. On the other hand, dark triangles are more likely to develop following labial movement of imbricated or palatally placed incisors and closure of a diastema. Clinicians should be alert to the possibility of dark triangles developing in the latter group, particularly in older patients.