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. 2013 Aug 14;9:21. doi: 10.1186/1746-160X-9-21

Table 4.

Distribution of the root length reduction during orthodontic treatment of the individual teeth (upper and lower incisors, canines, first molars) (each n = 100, overall n = 1600): post-treatment RCR relative to pre-treatment RCR (rRCR), absolute (n) and relative (%) frequencies

  Tooth
rRCR
16
13
12
11
21
22
23
26
46
43
42
41
31
32
33
36
rRCR < 80
7
12
6
10
7
2
7
8
1
2
1
10
14
5
6
3
7.0
12.0
6.0
10.0
7.0
2.0
7.0
8.0
1.0
2.0
1.0
10.0
14.0
5.0
6.0
3.0
80 ≤ rRCR < 90
11
11
15
11
12
11
16
8
9
9
18
15
12
11
7
14
11.0
11.0
15.0
11.0
12.0
11.0
16.0
8.0
9.0
9.0
18.0
15.0
12.0
11.0
7.0
14.0
90 ≤ rRCR < 100
22
24
28
22
22
29
27
36
38
31
25
27
25
32
24
33
22.0
24.0
28.0
22.0
22.0
29.0
27.0
36.0
38.0
31.0
25.0
27.0
25.0
32.0
24.0
33.0
rRCR ≥ 100
60
53
51
57
59
58
50
48
52
58
56
48
49
52
63
50
60.0
53.0
51.0
57.0
59.0
58.0
50.0
48.0
52.0
58.0
56.0
48.0
49.0
52.0
63.0
50.0
Total (n) 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100