Frequency evaluation of different extraction protocols in orthodontic treatment during 35 years

Progress in Orthodontics

Table 2 Frequency of one-phase and two-phase treatments and re-planned cases in all evaluated intervals (proportion test)

Interval	N	One-phase		Two-phase		Not replanned		Re-planned
Interval	N	N	%	N	%	N	%	N	%
1	105	104	99.05	1	0.95^A	104	99.05	1	0.95^BC
(1973 to 1977)	105	104	99.05	1	0.95^A	104	99.05	1	0.95^BC
2	146	145	99.32	1	0.68^A	143	97.94	3	2.06^BC
(1978 to 1982)	146	145	99.32	1	0.68^A	143	97.94	3	2.06^BC
3	314	309	98.73	5	1.27^A	305	97.13	9	2.87^BC
(1983 to 1987)	314	309	98.73	5	1.27^A	305	97.13	9	2.87^BC
4	666	636	98.05	30	1.95^AB	653	98.05	13	1.95^BC
(1988 to 1992)	666	636	98.05	30	1.95^AB	653	98.05	13	1.95^BC
5	1262	1172	95.17	90	4.83^BC	1226	97.15	36	2.85^BC
(1993 to 1997)	1262	1172	95.17	90	4.83^BC	1226	97.15	36	2.85^BC
6	612	521	92.81	91	7.19^D	587	95.91	25	4.09^AB
(1998 to 2002)	612	521	92.81	91	7.19^D	587	95.91	25	4.09^AB
7	308	296	93.18	12	6.82^AB	306	99.35	2	0.65^CD
(2003 to 2007)	308	296	93.18	12	6.82^AB	306	99.35	2	0.65^CD
Total	3,413	3,183	93.26	230	6.74	3324	97.39	89	2.61
		χ		101.272				12.726
		P		0.0000*				0.0475*

Different letters in two-phase treatment or in re-planned cases represent statistically significant differences. *Statistically significant at P < 0.05.