Table 2. Descriptive statistics of the LII and PAR index and the result of the significant tests.

CA: Clear Aligners group, FA: Fixed Appliance group, LII: Little's irregularity index, UANT: Upper anterior segment alignment, LANT: Lower anterior segment alignment, AP: Anterior-posterior occlusion, TRANS: Transverse occlusion, VERT: Vertical occlusion, OJ: Overjet, OB: Overbite, MID: Midline, WPAR: Weighted PAR, RED: Reduction percent.

† Employing a two-sample t-test, ‡ Employing a chi-square test.

*Bonferroni's correction was used to adjust the significance level to 0.006.

Variable		CA group (n=18)		FA group (n=18)		CA vs. FA
		T0	T1	T0	T1	T1
		Mean ± Standard deviation	Mean ± Standard deviation	Mean ± Standard deviation	Mean ± Standard deviation	Mean difference	95% CI	p-value
LII	Upper Jaw†	12.94 ± 2.14	0.58 ± 0.69	11.19 ± 2.89	0.47 ± 0.36	0.11	(-0.268; 0.490)	0.551
	Lower Jaw†	10.55 ± 3.49	0.69 ± 0.87	11.66 ± 2.72	0.61 ± 0.47	0.08	(-0.399; 0.566)	0.725
PAR index	UANT†	7.27 ± 1.87	0.44 ± 1.87	6.55 ± 2.12	0.05 ± 0.23	0.38	(0.114; 0.663)	0.008
	LANT†	6.22 ± 1.39	0.83 ± 0.98	6.27 ± 2.13	0.22 ± 0.54	0.61	(0.065; 1.157)	0.030
	AP†	1.05 ± 1.16	1.16 ± 0.61	2.16 ± 1.09	1.22 ± 0.87	-0.05	(-0.573; 0.461)	0.828
	TRANS†	0.55 ± 0.92	0.05 ± 0.23	0.66 ± 0.84	0.33 ± 0.76	-0.27	(-0.672; 0.117)	0.157
	VERT†	1.22 ± 0.94	0.27 ± 0.66	0.72 ± 0.82	0.38 ± 0.60	-0.11	(-0.545; 0.322)	0.605
	OJ†	13.00 ± 6.90	0.66 ± 1.94	9.00 ± 5.54	0.66 ± 0.84	0.00	(-1.314; 1.314)	1.00
	OB†	1.11 ± 1.84	0.66 ± 1.18	0.66 ± 1.18	0.33 ± 1.02	0.33	(-0.420; 1.087)	0.375
	MID†	3.55 ± 2.33	1.33 ± 1.94	4.44 ± 2.70	1.33 ± 2.37	0.00	(-1.473; 1.473)	1.00
	WPAR†	33.89 ± 8.01	5.50 ± 2.85	30.44 ± 6.69	4.05 ± 2.96	1.44	(-0.527; 3.416)	0.146
	Score reduction†	28.39 ± 8.51		26.39 ± 5.76		2.00	(-2.950; 6.950)	0.416
	RED%†	87.08 ± 8.37		83.52 ± 9.15		-3.56	(-9.510; 2.380)	0.232
	Improved cases‡ Number (%)	18/18 (100%)		18/18 (100%)		-	-	1.00
	Great Improvement‡ Number (%)	14/18 (88.9%)		15/18 (91.7%)		-	-	0.674