Table 2. Compensatory differences of the axial inclination of maxillary and mandibular first molars between different malocclusion groups evaluated by ANOVA.
| Classification | n | UM/PP | LM/MP | ||||
|---|---|---|---|---|---|---|---|
| (Mean±s.d.)/ ° | P value | Observed powera | (Mean±s.d.)/ ° | P value | Observed powera | ||
| Age/year | 0.000** | 1.000 | 0.858 | 0.074 | |||
| <12 | 340 | 77.022±5.006 | 96.356±5.330 | ||||
| 12–16 | 788 | 79.112±5.327 | 96.457±5.592 | ||||
| >16 | 275 | 84.311±5.693 | 96.610±6.347 | ||||
| Angle classification | 0.000** | 1.000 | 0.000** | 1.000 | |||
| 1 | 635 | 80.860±5.475 | 96.589±5.649 | ||||
| 2 | 547 | 77.539±5.704 | 95.535±5.490 | ||||
| 3 | 221 | 81.233±5.866 | 98.395±5.759 | ||||
| Skeletal classification | 0.000** | 1.000 | 0.000** | 1.000 | |||
| 1 | 588 | 80.412±5.444 | 96.936±5.623 | ||||
| 2 | 646 | 78.159±5.740 | 95.609±5.617 | ||||
| 3 | 169 | 82.482±6.209 | 98.080±5.635 | ||||
| MP/SN classification | 0.000** | 0.995 | 0.000** | 1.000 | |||
| Low-angle | 56 | 81.585±6.282 | 91.479±4.474 | ||||
| Average angle | 703 | 80.179±6.031 | 94.614±5.129 | ||||
| High-angle | 644 | 78.848±5.539 | 98.914±5.299 | ||||
| Total | 1 403 | 79.624±5.867 | 96.463±5.684 | ||||
ANOVA, analysis of variance; n, number of cases; s.d., standard deviation; UM/PP, inferoposterior crossing angle of the axis of the upper first molar with the palatal plane; LM/MP, anterosuperior crossing angle of the axis of the lower first molar with the mandibular plane.
**
P < 0.01.
a: computed using α = 0.05.