2004 Volume 32 Issue 1 Pages 8-13
The purpose of our study is to investigate the incidence of post-orthodontic open gingival embrasures (black triangles) and to examine the association with open gingival embrasure in patients who underwent orthodontic/surgical combined treatment. Twenty-four subjects were randomly chosen from patients diagnosed as skeletal Class III reversed occlusion in Hokkaido University Hospital Orthodontic clinic. The incidences of 5 gingival embrasures from canine to canine in lower dental arch were evaluated at initial examination, before surgery and at debonding. A sample was divided into two groups: normal gingival embrasure (group A) and open gingival embrasure (group B). The following variables were evaluated the association with open gingival embrasure : age, treatment duration, Curve of Spee, arch length discrepancy, inter-maxillary elastics, the amount of surgical counter-clock-wise rotation of the mandible, change in crown length and the distance of incisor movement. The following results were obtained. 1. 12 of 24 patients had the black triangles. 2. 9 of 24 patients had the black triangles at debonding. 3. There were no statistical differences between group A and B regarding with age, treatment duration, intermaxillary elastic, the amount of upward rotation of the mandibule at surgery. 4. The Curve of Spee in group A was deeper than group B and this was statistically significant. 5. Incisor in group A had longer crown than one in group B, this was also statistically significant. 6. Incisor in group A had been elongated greater than in group B, this was also statistically significant.
