Ko-Kimura Natsue, Kimura-Hayashi Masami, Yamaguchi Masaru, Ikeda Tadataka, Meguro Daijiro, Kanekawa Mika, Kasai Kazutaka
Department of Orthodontics, Nihon University, School of Dentistry at Matsudo City, Chiba, Japan.
Aust Orthod J. 2003 Apr;19(1):19-24.
Open gingival embrasures or "black triangles" can be an undesirable outcome of adult orthodontic treatment. The aims of the present study were to determine the prevalence of open gingival embrasures in a group of orthodontic patients, and to determine if open gingival embrasures were related to: age at the start of treatment, the severity of pretreatment crowding of the mandibular incisors, the duration of treatment or changes in alveolar bone height. The subjects were 80 orthodontic patients (33 males, 47 females) between 15 and 31 years of age. Open gingival embrasures were found in 43.7 per cent of all subjects, while in subjects over 20 years of age the prevalence was 66.7 per cent. In relation to the amount of crowding 42.8 per cent of the subjects with less than 4 mm crowding had open gingival embrasures, 41.2 per cent of those with between 4 and 8 mm crowding had open gingival embrasures, and 50 per cent of those with more than 8 mm crowding had open gingival embrasures. The groups were not significantly different. Approximately 42 per cent of the subjects in the shorter treatment group had open gingival embrasures, and 44.4 per cent of those whose treatment took longer than 3 years had open gingival embrasures. This difference was not statistically significant. Cephalometric measurements of mandibular alveolar bone height indicate that open gingival embrasures were more likely to be due to resorption of the alveolar crest rather than extrusion of the mandibular incisors. In conclusion, open gingival embrasures were more frequently found in patients over 20 years of age than in younger patients, and were associated with resorption of the alveolar crest.
牙龈间隙开放或“黑三角”可能是成人正畸治疗的不良后果。本研究的目的是确定一组正畸患者中牙龈间隙开放的患病率，并确定牙龈间隙开放是否与以下因素相关：治疗开始时的年龄、下颌切牙治疗前拥挤的严重程度、治疗持续时间或牙槽骨高度的变化。研究对象为80名年龄在15至31岁之间的正畸患者（33名男性，47名女性）。在所有受试者中，43.7%存在牙龈间隙开放，而在20岁以上的受试者中，患病率为66.7%。关于拥挤程度，拥挤程度小于4mm的受试者中，42.8%有牙龈间隙开放；拥挤程度在4至8mm之间的受试者中，41.2%有牙龈间隙开放；拥挤程度大于8mm的受试者中，50%有牙龈间隙开放。各组之间无显著差异。治疗时间较短组中约42%的受试者有牙龈间隙开放，治疗时间超过3年的受试者中44.4%有牙龈间隙开放。这种差异无统计学意义。下颌牙槽骨高度的头影测量表明，牙龈间隙开放更可能是由于牙槽嵴吸收而非下颌切牙的伸长。总之，20岁以上患者比年轻患者更易出现牙龈间隙开放，且与牙槽嵴吸收有关。
