Table 4. ANOVA comparison of compensatory differences of the axial inclination of the mandibular first molars between groups within each stratification.

Classification	<12 years		12–16 years		>16 years		P value
	n	(Mean±s.d.)/ °	n	(Mean±s.d.)/ °	n	(Mean±s.d.)/ °
Angle classification
1	127	96.310±5.512	366	96.539±5.605	142	96.969±5.901	0.614
2	145	95.754±5.173	309	95.648±5.306	93	94.815±6.486	0.376
3	68	97.722±5.139	113	98.405±5.857	40	99.513±6.414	0.297
P value		0.042*		0.000**		0.000**
Skeletal classification
1	132	96.766±5.626	350	96.929±5.484	106	97.171±6.103	0.859
2	156	95.812±5.038	358	95.548±5.544	132	95.532±6.442	0.874
3	52	96.944±5.359	80	98.461±5.568	37	98.852±6.053	0.205
P value		0.219		0.000**		0.009**
MP/SN classification
Low-angle	6	89.890±2.163	33	91.151±4.116	17	92.676±5.548	0.347
Average angle	168	94.648±4.807	394	94.398±5.000	141	95.177±5.809	0.300
High-angle	166	98.318±5.146	361	99.190±4.986	117	98.909±6.332	0.215
P value		0.000**		0.000**		0.000**
Total	340	96.356±5.330	788	96.457±5.592	275	96.610±6.347

ANOVA, analysis of variance; n, number of cases; MP/SN, anteroinferior crossing angle of the mandibular plane with the anterior cranial base plane.

^*P < 0.05, **P<0.01.