Table 1 presents descriptive statistics for the BAH across three distinct anatomical sites. In the U56 region, the BAH was 9.93 ± 3.78 mm, which was significantly greater than that for U6md (8.01 ± 2.71 mm) and U67 (8.18 ± 2.56 mm). The comparison between males and females revealed no significant differences in BAH (Table S2). However, different age groups exhibited variations, with the BAH in the adolescent group being consistently lower than that in the adult group for all three regions (Table S3). Among different sagittal skeletal groups, Class I individuals had the lowest BAH in the U56 area (Table S4). Furthermore, the BAH for hypodivergent participants was significantly greater than that for hyperdivergent participants in the U67 area (Table S5).
Table 1
Buccal alveolar bone heights (mm) at the three anatomical sites.
Area | Mean | SD | P25 | P50 | P75 | H | P |
U56a | 9.93 | 3.78 | 7.19 | 9.31 | 11.87 | 70.05 | < 0.001* |
U6mdb | 8.01 | 2.71 | 6.28 | 7.68 | 9.19 |
U67b | 8.18 | 2.56 | 6.38 | 7.90 | 9.70 |
SD: standard deviation; Kruskal-Wallis test; |
* Statistically significant at P < 0.001.
U56, between the maxillary second premolar and the first molar
U6md, between the mesiobuccal and distobuccal roots of the first molar
U67, between the first and second molar
a,b statistically significant differences were observed between groups marked with the different letter.
Table 2 presents descriptive statistics for BAT across various regions and planes. The BAT exhibited an increase at the 5, 7, and 9 mm planes, with the U67 region displaying the greatest thickness, followed by the U6md region, while the U56 region showed the smallest thickness (Fig. 3, Table S6). A comparison between males and females showed no significant differences across different regions (Table S7). Meanwhile, the BAT in the adolescent group was found to be greater than that in the adult group (Table S8). When comparing different sagittal skeletal types, the BAT in Class I was greater than that in Class III (Table S9). Among the various vertical facial types, the normodivergent group had the highest BAT, but the differences among these groups were not statistically significant (Table S10).
Table 2
Buccal alveolar bone thickness (mm) in different regions.
Area | Plane | Mean | SD | Percentile | F/H | P |
25th | 50th | 75th |
U56 | 5 mma | 2.23 | 0.91 | 1.53 | 2.11 | 2.88 | 14.25 | < 0.001K* |
7 mma | 2.34 | 1.10 | 1.55 | 2.18 | 3.09 |
9 mmb | 2.68 | 1.47 | 1.66 | 2.42 | 3.47 |
U6md | 5 mma | 2.65 | 1.05 | 1.87 | 2.56 | 3.31 | 32.88 | < 0.001K* |
7 mma | 2.84 | 1.29 | 1.91 | 2.69 | 3.68 |
9 mmb | 3.38 | 1.72 | 2.07 | 3.09 | 4.47 |
U67 | 5 mma | 3.31 | 0.85 | 2.71 | 3.26 | 3.82 | 66.87 | < 0.001A* |
7 mmb | 3.65 | 0.99 | 3.03 | 3.61 | 4.25 |
9 mmc | 4.18 | 1.29 | 3.28 | 4.08 | 4.93 |
SD: standard deviation; K: Kruskal-Wallis test; A: One-way ANOVA; |
* Statistically significant at P < 0 .05.
U56, between the maxillary second premolar and the first molar
U6md, between the mesiobuccal and distobuccal roots of the first molar
U67, between the first and second molar
a,b,c statistically significant differences observed between groups marked with the different letter.
Table 3 presents descriptive statistics for BID across various regions and planes. The BID increased at the 5, 7, and 9 mm planes, with the largest distance observed in the U56 region, followed by the U67 region, and the smallest distance recorded in the U6md region (Fig. 3, Table S11). Compared to males, the BID was larger among females in the U67 region, but smaller in the U6md region (Table S12). Compared to the adolescent group, the adult group had larger BID at the 5, 7, and 9 mm planes in the U67 region, and smaller BID at the 5 mm plane in the U56 region (Table S13). Among different sagittal skeletal types, the BID in Class I individuals was the largest in the U56 and U6md regions, but the smallest in the U67 region (Table S14). The differences among different vertical facial types were not statistically significant (Table S15).
Table 3
Buccal interradicular distance (mm) at different regions.
Area | Plane | Mean | SD | Percentiles | F/H | P |
25th | 50th | 75th |
U56 | 5 mma | 3.52 | 0.98 | 2.83 | 3.56 | 4.22 | 149.15 | < 0.001A* |
7 mmb | 4.07 | 1.15 | 3.22 | 4.10 | 4.88 |
9 mmc | 5.01 | 1.44 | 4.00 | 5.02 | 5.95 |
U6md | 5 mma | 1.70 | 0.59 | 1.29 | 1.68 | 2.08 | 35.90 | < 0.001K* |
7 mmb | 1.98 | 0.74 | 1.46 | 1.92 | 2.46 |
9 mmb | 2.10 | 1.05 | 1.26 | 1.97 | 2.71 |
U67 | 5 mma | 2.00 | 1.08 | 1.27 | 1.83 | 2.58 | 69.90 | < 0.001 K* |
7 mma | 2.19 | 1.26 | 1.23 | 1.97 | 2.92 |
9 mmb | 2.84 | 1.52 | 1.67 | 2.64 | 3.86 |
SD: standard deviation; K: Kruskal-Wallis test; A: One-way ANOVA; |
* Statistically significant at P < 0 .001.
U56, between the maxillary second premolar and the first molar
U6md, between the mesiobuccal and distobuccal roots of the first molar
U67, between the first and second molar
a,b,c statistically significant differences observed between groups marked with the different letter.
Table 4 provides descriptive statistics for the MRS at the 5, 7, and 9 mm planes. The MRS exhibited a sequential increase with increasing plane distance. This progression was statistically significant. A comparison between males and females revealed no significant differences (Table S16). In terms of age, the MRS in the adolescent group was consistently smaller than that in the adult group at all three planes (Table S17). Within different sagittal skeletal groups, Class I individuals exhibited a smaller MRS than those in the remaining two groups (Table S18). However, when comparing different vertical facial types, there were no significant differences (Table S19). Furthermore, compared to individuals with congenitally missing maxillary third molars, those without this condition displayed a wider MRS, with statistically significant differences noted at the 7 and 9 mm planes (Table S20).
Table 4
Maxillary retromolar space (mm) at the 5, 7, and 9 mm planes.
Plane | Mean | SD | Percentiles | H | P |
25th | 50th | 75th |
5 mma | 9.33 | 2.70 | 7.50 | 9.63 | 11.20 | 84.34 | < 0.001* |
7 mmb | 10.29 | 2.51 | 8.70 | 10.45 | 11.94 |
9 mmc | 11.08 | 2.41 | 9.65 | 11.23 | 12.60 |
SD: standard deviation; Kruskal-Wallis test; |
* Statistically significant at P < 0 .001.
a,b,c statistically significant differences observed between groups marked with the different letter.