Abstract: Objective Determine the buccal and palatal bone thickness at different reference lines and the distance from cemento-enamel junction(CEJ) to labial bone crest of the maxillary central incisor. To study the relationship between gingival biotype and gender、age、crown form、the underlying bone thickness and the distance from CEJ to labial bone crest of the maxillary central incisor. Methods 118 volunteers with health gingiva were included. The buccal and palatal bone thickness which were measured at 3 locations and the distance from CEJ to labial bone crest were determined by CBCT. Gingival biotype of those volunteers was confirmed by the aid of a periodontal probe. Results There is no relation between the gingival biotype and gender、age、crown form of the maxillary central incisor. The distance from CEJ to labial bone crest was 2.63±0.98mm，the correlation coefficient (r) values between the gingival biotype and this distance was -0.051（P＞0.05）. The percentage of partially missed labial bone was 27.1%. The correlation coefficient (r) values between the gingival biotype and labial bone thickness which were at 3，5mm below the CEJ were 0.747、0.281（P＜0.05）respectively. Conclusions ①About the maxillary central incisor，around one third of labial bone was partially missed. No relation was detected between the gingival biotype and the distance as mentioned above. ②There is positive relation between the gingival biotype and labial bone thickness when the labial bone was intact.

Key words: Gingival biotype, Alveolar bone thickness, Cone-beam CT（CBCT）, Esthetic zone