Table 3.

Arch dimensions and LII: adjusted means, 95% confidence interval (CI), and P values.

			UIC	UIP	UIM	UAL	LIC	LIP	LIM	LAL	LII
CAD/CAM	T0	Mean	34.1	42.0	50.4	38.2	26.6	34.3	43.4	34.0	0.7
		CI	33.7 to 34.5	41.5 to 42.5	49.9 to 51.0	37.7 to 38.7	26.4 to 27.0	33.9 to 34.6	42.9 to 44.0	33.5 to 34.5	0.6 to 0.8
	T6	Mean	34.2	42.1	50.1	38.3	26.7	34.4	43.5	34.0	0.9
		CI	33.8 to 34.7	41.6 to 42.5	49.5 to 50.8	37.7 to 38.8	26.4 to 27.0	34.1 to 34.8	42.9 to 44.0	33.5 to 34.5	0.8 to 1.1
	T0 vs T6	P value	0.221	0.747	0.117	0.276	0.855	0.089	0.925	0.781	<0.001*
Conventional	T0	Mean	34.0	42.0	50.4	38.1	26.5	34.3	43.8	33.7	0.9
		CI	33.6 to 34.4	41.5 to 42.4	49.8 to 51.0	37.6 to 38.7	26.2 to 26.8	34.0 to 34.7	43.2 to 44.3	33.2 to 34.2	0.8 to 1.0
	T6	Mean	34.1	41.8	50.3	38.2	26.5	34.4	43.7	33.8	1.0
		CI	33.7 to 34.6	41.3 to 42.3	49.7 to 51.0	37.7 to 38.7	26.2 to 26.8	34.1 to 34.8	43.2 to 44.3	33.2 to 34.3	0.9 to 1.2
	T0 vs T6	P value	0.469	0.143	0.592	0.515	0.639	0.316	0.835	0.589	0.054
CAD/CAM vs Conventional	T0 (n = 180)a	P value	0.835	0.914	0.972	0.860	0.545	0.556	0.413	0.415	0.116
	T6 (n = 163)b	P value	0.708	0.463	0.723	0.815	0.412	0.664	0.435	0.505	0.387

UIC, upper inter-canine distance; UIP, upper inter-premolar distance; UIM, upper inter-molar distance; UAL, upper arch length; LIC, lower inter-canine distance; LIP, lower inter-premolar distance; LIM, lower inter-molar distance; LAL, lower arch length; LII, Little’s Irregularity Index.

one digital model was lost.

four digital models were lost, 13 patients did not attend the T6 visit, and 1 patient had no models taken because of a re-treatment in the upper arch due to space opening after retainer failure.

P < 0.001.