A two-year comparative assessment of retention of arch width increases between modified vacuum-formed and Hawley retainers: a multi-center randomized clinical trial

Progress in Orthodontics

Table 4 Independent samples T-test

Variable	Type of retainer	Mean	Mean difference	95% CI of the difference	P value
Fitting	mVFRs	7.08	1.24	− 0.526, 3.013	.160
Fitting	HRs	5.84	1.24	− 0.526, 3.013	.160
Speech	mVFRs	7.32	1.76	− 0.247, 3.759	.083
Speech	HRs	5.56	1.76	− 0.247, 3.759	.083
Appearance	mVFRs	8.02	1.84	0.209, 3.460	.029*
Appearance	HRs	6.18	1.84	0.209, 3.460	.029*
Oral hygiene	mVFRs	7.63	0.77	− 1.053, 2.606	.389
Oral hygiene	HRs	6.86	0.77	− 1.053, 2.606	.389
Durability	mVFRs	7.05	0.25	− 1.700, 2.192	.797
Durability	HRs	6.80	0.25	− 1.700, 2.192	.797
Comfort	mVFRs	7.69	1.63	− 0.261, 3.521	.088
Comfort	HRs	6.06	1.63	− 0.261, 3.521	.088
Total mean additive score	mVFRs	7.46	1.24	− 0.277, 2.772	.104
Total mean additive score	HRs	6.22	1.24	− 0.277, 2.772	.104

mVFRs indicate modified vacuum-formed retainers; HRs, Hawley retainers; CI, confidence interval
Level of significance set at 0.05. *Significant P values