The inflection point: a torque reference for lingual bracket positioning on the palatal surface curvature of the maxillary central incisor

Progress in Orthodontics

Table 2 Descriptive statistics of the torque angle values of the PSC of the 50 incisors from [P₁] to [P₁ + 11] and at the inflection point. Descriptive statistics of the inflection point location on the PSC of the 50 studied incisors is also shown in this table. N stands for frequency of recorded site and SD for standard deviation

Site	N	Minimum	Maximum	Range	Mean	SD
[P₁]	50	− 3.30	28.62	31.92	9.15	7.90
[P₁ + 0.5]	50	− 7.62	19.25	26.87	4.95	6.32
[P₁ + 1]	50	− 9.63	11.66	21.28	0.04	5.40
[P₁ + 1.5]	50	− 18.38	3.42	21.80	− 6.10	5.38
[P₁ + 2]	50	− 32.14	− 2.59	29.55	− 14.07	6.70
[P₁ + 2.5]	50	− 44.96	− 7.59	37.37	− 24.44	9.40
[P₁ + 3]	50	− 48.39	− 11.80	36.59	− 31.88	9.30
[P₁ + 3.5]	50	− 60.77	− 16.91	43.86	− 36.34	8.79
[P₁ + 4]	50	− 52.64	− 20.16	32.48	− 35.84	6.61
[P₁ + 4.5]	50	− 45.96	− 18.24	27.73	− 33.31	6.22
[P₁ + 5]	50	− 43.15	− 15.51	27.64	− 29.75	6.21
[P₁ + 5.5]	50	− 50.27	− 9.85	40.42	− 26.04	7.47
[P₁ + 6]	50	− 35.48	6.28	41.77	− 20.62	8.87
[P₁ + 6.5]	50	− 31.96	7.64	39.60	− 14.00	9.84
[P₁ + 7]	50	− 27.82	21.41	49.23	− 7.33	11.73
[P₁ + 7.5]	50	− 20.81	40.84	61.65	0.10	13.77
[P₁ + 8]	45	−14.02	48.09	62.11	9.18	15.83
[P₁ + 8.5]	34	− 9.88	50.10	59.98	13.32	14.86
[P₁ + 9]	25	− 5.31	46.92	52.24	16.69	12.74
[P₁ + 9.5]	12	− 1.69	37.92	39.61	18.09	11.92
[P₁ + 10]	4	4.91	34.30	29.39	20.77	12.07
[P₁ + 10.5]	3	14.50	32.31	17.81	24.63	9.16
[P₁ + 11]	1	32.92	32.92	0.00	32.92	–
Inflection point	50	− 70.84	− 22.71	48.13	− 45.82	9.98
Inflection point location	–	[P₁ + 2.03]	[P₁ + 6.17]	4.14	[P₁ + 3.73]	0.94