CBCT-Based Three-Tier Classification of Posterior Supracrestal Tissue Phenotypes: Analysis of Influencing Factors and Implications for Implant Surgical Planning.

OBJECTIVES: To establish a novel comprehensive classification system for supracrestal soft tissue height (STH) in posterior edentulous regions. On the basis of cone-beam computed tomography (CBCT) measurements of posterior STH, the distribution proportion of each STH category and its influencing factors were analyzed. Implant protocols were proposed according to class. MATERIALS AND METHODS: CBCT images of 600 posterior edentulous teeth from 410 patients who met the inclusion criteria were included (average number of edentulous sites per patient is 1.46). The STHs of the edentulous areas were measured and divided into three classes: Class I (≤3 mm), Class II (3-4.5 mm), and Class III (≥4.5 mm). The percentage of STHs in each class was determined, and the relationships between the STH and sex, age, jaw, and tooth position were analyzed. RESULTS: Class I accounted for most STHs (75.3%), Class II accounted for 23.5%, and Class III accounted for 7 cases (1.2%). Sex was associated with STH, with thicker STHs (2.63±0.81 mm) in males than in females (2.38±0.77 mm) (p<0.05); the female group had a greater probability of thin STH (79.5%). The STH of the maxillary region (2.70±0.78 mm) was thicker than that of the mandible (2.25±0.73 mm), and the STH of the second molar (2.65±0.87 mm) was thicker than those of the premolar (2.45±0.74 mm) and first molar (2.33±0.73 mm) (p<0.05). Age was not associated with STH. CONCLUSION: Based on our classification, most sites belonged to Class I, followed by Class II, with few Class III cases. Gender, jaw position and tooth site correlated with posterior STH, whereas age did not.