Table 5. Severity of MSM distal ERR and its association with related influence factors.
| Variables | Severity of MSM distal ERR | Total | χ2 | p | |||
|---|---|---|---|---|---|---|---|
| No | Mild | Moderate | Severe | (N=1007) | |||
| (N=751) | (N=192) | (N=47) | (N=17) | ||||
| Gender | |||||||
| Male | 346 | 85 | 25 | 10 | 466 | 2.304 | 0.512 |
| (74.2%) | (18.2%) | (5.4%) | (2.1%) | (100.0%) | |||
| Female | 405 | 107 | 22 | 7 | 541 | ||
| (74.9%) | (19.8%) | (4.1%) | (1.3%) | (100.0%) | |||
| Age | |||||||
| 18–25 | 143 | 72 | 10 | 0 | 225 | N/A† | 0.000***† |
| (63.6%) | (32.0%) | (4.4%) | (0.0%) | (100.0%) | |||
| 26–35 | 216 | 66 | 12 | 8 | 302 | ||
| (71.5%) | (21.9%) | (4.0%) | (2.6%) | (100.0%) | |||
| 36–45 | 208 | 25 | 9 | 7 | 249 | ||
| (83.5%) | (10.0%) | (3.6%) | (2.8%) | (100.0%) | |||
| 46–55 | 89 | 17 | 10 | 2 | 118 | ||
| (75.4%) | (14.4%) | (8.5%) | (1.7%) | (100.0%) | |||
| ≥56 | 95 | 12 | 6 | 0 | 113 | ||
| (84.1%) | (10.6%) | (5.3%) | (0.0%) | (100.0%) | |||
| Winter’s classification | |||||||
| Vertical impaction | 369 | 7 | 0 | 0 | 376 | N/A† | 0.000***† |
| (98.1%) | (1.9%) | (0.0%) | (0.0%) | (100.0%) | |||
| Mesioangular impaction | 166 | 95 | 21 | 11 | 293 | ||
| (56.7%) | (32.4%) | (7.2%) | (3.8%) | (100.0%) | |||
| Horizontal impaction | 134 | 82 | 21 | 4 | 241 | ||
| (55.6%) | (34.0%) | (8.7%) | (1.7%) | (100.0%) | |||
| Distoangular impaction | 65 | 0 | 0 | 0 | 65 | ||
| (100.0%) | (0.0%) | (0.0%) | (0.0%) | (100.0%) | |||
| Other types of impaction | 17 | 8 | 5 | 2 | 32 | ||
| (53.1%) | (25.0%) | (15.6%) | (6.3%) | (100.0%) | |||
| Pell & Gregory’s classification (Ramus) | |||||||
| Class I | 353 | 20 | 4 | 2 | 379 | 125.571 | 0.000***† |
| (93.1%) | (5.3%) | (1.1%) | (0.5%) | (100.0%) | |||
| Class II | 303 | 113 | 26 | 8 | 450 | ||
| (67.3%) | (25.1%) | (5.8%) | (1.8%) | (100.0%) | |||
| Class III | 95 | 59 | 17 | 7 | 178 | ||
| (53.4%) | (33.1%) | (9.6%) | (3.9%) | (100.0%) | |||
| Pell & Gregory’s classification (Occlusal) | |||||||
| Position A | 466 | 52 | 10 | 1 | 529 | 126.974 | 0.000*** |
| (88.1%) | (9.8%) | (1.9%) | (0.2%) | (100.0%) | |||
| Position B | 213 | 93 | 19 | 9 | 334 | ||
| (63.8%) | (27.8%) | (5.7%) | (2.7%) | (100.0%) | |||
| Position C | 72 | 47 | 18 | 7 | 144 | ||
| (50.0%) | (32.6%) | (12.5%) | (4.9%) | (100.0%) | |||
| Contact status between IMTM and MSM | |||||||
| No contact | 150 | 5 | 0 | 0 | 155 | N/A† | 0.000***† |
| (96.8%) | (3.2%) | (0.0%) | (0.0%) | (100.0%) | |||
| Point contact | 26 | 10 | 0 | 0 | 36 | ||
| (72.2%) | (27.8%) | (0.0%) | (0.0%) | (100.0%) | |||
| Surface-to-surface contact | 575 | 177 | 47 | 17 | 816 | ||
| (70.5%) | (21.7%) | (5.8%) | (2.1%) | (100.0%) | |||
| MSM distal alveolar bone condition | |||||||
| Compressive resorption | 697 | 167 | 41 | 17 | 922 | N/A† | 0.028*† |
| (75.6%) | (18.1%) | (4.4%) | (1.8%) | (100.0%) | |||
| Inflammatory resorption | 54 | 25 | 6 | 0 | 85 | ||
| (63.5%) | (29.4%) | (7.1%) | (0.0%) | (100.0%) | |||
* p<0.05, *** p<0.001
† p-values were calculated using Fisher’s exact test with Monte Carlo simulation (10,000 replications), as the chi-squared test was not applicable due to violations of its assumptions (≥20% of cells had expected counts of 1 < T < 5).