The Periodontal Biotype And Relationship Between Periodontal Biotype Characteristics

Objective:To explore the. relationship between gingival thickness, the underlying alveolar bone thickness and sagittal root position in the maxillary anterior and their associations which is measured by cone-beam computed tomography (CBCT). Oral and gypsum measurements are used to analysis the associations of periodontal biotype characteristics. To apply the theoretical foundation for the aesthetic dentistry, implant treatment planning and assessment of therapeutic effect.Methods:40 young volunteers with periodontal healthy were involved in this research (16 males and 24 females, aged 23 to 34years, mean age 26.3 years). The periodontal probe was used to divide the gingiva from thick to thin. Six records were measured by CBCT:gingival thickness (GT) were measured at the cemento-enamel junction (CEJ) level, buccal bone thickness (BT) were measured at 3 locations:lmm, 3mm,5mm below the alveolar crest, the sagittal angle between the long axis of teeth and the long axis of the respective alveolar bone, and distance from the CEJ to the alveolar bone crest (CEJ-BC). Oral and gypsum measurements are used to measure the keratinized tissue width (KT), the crown width\crown length ratio (CW\CL), the free gingival margin curvature. Independ T-test was used to examine the statistical significance of gingival thickness difference between the thick biotype and thin biotype which were divided by periodontal probe, periodontal biotype characteristics differences between the thick biotype (gingival thickness> 1mm) and thin biotype (gingival thickness<1mm). Pearson correlation analyses was used to examine the correlation between the GT, BT, and the sagittal angle between teeth and alveolar bone; the correlation between periodontal biotype characteristics and GT, BT. Multiple linear regression analyses was performed to test the difference of the effect between the related factors.Results:1.The average thickness of gingiva was 1.08±0.34mm. There were significant difference of gingival thickness between the thick biotype (1.18±0.33mm) and thin biotype (0.93± 0.31mm) which were divided by periodontal probe.2. The average thickness of alveolar bone was 0.79±0.29 mm. There were 71% of locations with bone thickness<1mm,28% of locations with bone thickness<2mm and> 1mm, only 1% locations with bone thickness>2mm.3. The average angle between teeth and alveolar bone was 18.01±8.96°. There were only 24% of locations with angle<10°,35% of locations with angle<20°and>10°,41% of locations with angle> 20°.4. The BT was positive associated with GT and the angle between teeth and alveolar bone respectively. Both of GT and the angle between teeth and alveolar bone were the influences of BT. Compared with the angle between teeth and alveolar bone, GT was more critical.5. There were differences between the thick biotype (gingival thickness>1mm) and thin biotype (gingival thickness<1mm). Compared with the thin biotype, the thick biotype was related with thicker bone thickness, wider keratinized tissue, square anatomic crown, flat free gingival margin and shorter CEJ-BC. CW\CL, KT, CEJ-BC, the free gingival margin curvature were associated with GT respectively. KT and CEJ-BC were associated with BT respectively. Both of KT and CEJ-BC were the influences of GT and BT.Conclusion:Alveolar bone and soft tissue could be distinguished clearly on the image of CBCT. The method of transparancy of the probing in the sulcus could analyse the gingival thickness qualitatively. The BT was positive associated with GT and the angle between teeth and alveolar bone respectively. GT and the angle between teeth and alveolar bone were the influences of BT. The alveolar bone in the maxillary anterior was thin. There was an angle between the long axis of teeth and the long axis of the alveolar bone. The locations with angle below 10° accounted a small portion. Compared with the thin biotype, the thick biotype was related with thicker bone thickness, wider keratinized tissue, square anatomic crown, flat free gingival margin and shorter CEJ-BC. CW\CL, KT, CEJ-BC, the free gingival margin curvature were associated with GT respectively. KT and CEJ-BC were associated with BT respectively.