Results
nerve numbness, pain, infection, PD, tooth, lingual nerve numbness
INFECTION
A total of 75 patients were enrolled in this prospective randomized clinical trial from September 2020 to December 2021. 6 patients withdrew from the study without follow-up, 2 patients in the control group did not fully participate in the 12-month follow-up, and 1 patient in test B group did not fully participate in the study. Therefore, we ultimately enrolled 66 patients, including 35 females and 31 males, aged from 19 to 50 years old, with an average age of 29.32 ± 6.23 years old. There were 22 patients in control group, including 14 females and 7 males; 23 patients in test A group, 10 females and 13 males; 21 patients in test B group, 11 females and 10 males. None of the patients had the bone materials removal due to infection, 1 case of lower lip or lingual nerve numbness occurred in the control group, and 4 cases of nerve numbness occurred in test B group, all of them recovered spontaneously within 1 week.At one week after surgery, there was no significant difference in PoSSe scales among all three groups. When the two test groups were compared separately, there were significant differences only in the time and degree of pain (p < 0.05), and no significant differences in the others (Table 
The PoSSe scale of all three groupsThe p value represents the statistical difference among the test groups (*Significant at the 5% level)In terms of postoperative periodontal probing depth, the PD of the three groups at different time points were shown in Fig. 4 (Supplementary Table 1). At 3rd month, the PD-B, PD-M and CG values of the control group were significant different compared with those of test A group and test B group (P < 0.05), indicating that the two test groups both showed better periodontal repair. At 6th month, the difference between PD-B values of test A and test B group was statistically significant, while PD-M values of test A or test B group compared with control group were statistically significant, test B group exhibited more advantages (p < 0.05). At 12th month, the PD-B, PD-M and PD-L values of test B group were statistically significant compared with those of test A and control groups, and test B group was more advantageous (p < 0.05). At 12th month, there was no statistical difference in CG values among all three groups (Fig. 
The periodontal probing depth and gingival recession measurements of all three groups at different time points. (Regarding image data measured by CBCT, the baseline values of each measurements before tooth extraction were shown in Fig. 
The post-hoc analysis by least-significant difference testThe p value represents the statistical difference between the test groups (*Significant at the 5% level)
Baseline values before tooth extraction on the CBCT. (
The CBCT measurements of all three groups at different time points. (
The CBCT images of all three groups at different time points. According to Pearson correlation coefficient analysis, AB/AC and BE showed a significant negative correlation at 3rd, 6th and 12th month, indicating that the deeper position of third molar crown, the larger vertical height of new bone formation; At 12th month, there was a significant negative correlation between CD and BE, indicating that in the long run, the larger width of third molar exposure on bone surface, the smaller vertical height of new bone. There was no significant correlation between CD and DF/CD at different time points, indicating that there was no significant correlation between the horizontal distance of new bone and the meso-distal width of the third molar bone surface exposure (Table 
Pearson correlation coefficient* P < 0.05, ** P < 0.01