Abstract: Objective The“black triangle”caused by loss of interproximal papilla usually lead to aesthetics deficiency. The purpose of this study was to investigate whether age, gender, and the distance from the contact point of the maxillary central incisors to the alveolar crest were correlated with the presence of the interproximal papilla by standardized periapical radiographs. Methods A total of 982 adult patients were received examination. The presence of the interproximal papilla was determined visually. The distance from the contact point to alveolar crest was measured by standardized periapical radiographs. Results When the distance between the contact point of two maxillary central incisors and alveolar crest was 5 mm or less, the probability of“black triangle” appearance were only 2.3%. When the distance ranged from 5-6 mm to 6-7 mm, the rates were up to 43.3% and 57.7%. When the distance exceeded 7 mm, the “black triangle”rate was up to 78.9%. Furthermore, the presence
of the“black triangle”was related to the distance from the contact point to alveolar crest and age, but not sex. Conclusion The distance from the contact point to the alveolar crest is highly associated with the presence or absence of the interproximal papilla.

Key words: interproximal papilla, black triangle, alveolar crest, contact point