A randomized clinical trial investigating pain associated with superelastic nickel–titanium and multistranded stainless steel archwires during the initial leveling and aligning phase of orthodontic treatment

Figures & data

Figure 1. CONSORT flow diagram

Figure 2. Least Square Means (LS-Means) profile plot of VAS scores (please refer to Table 2 for the description of time points)

Table 1. Baseline demographic and clinical characterstics data.

		Superelastic NiTi (n = 42)	Multistranded stainless steel (n = 43)
Age (years)		14.2 (1.9)	13.9 (2.0)
Sex	Male	21 (50%)	21 (48.8%)
	Female	21 (50%)	22 (51.2%)
Initial crowding (mm)		6.5 (1.3)	6.6 (1.4)
Extractions	No	18 (42.9%)	17 (39.6%)
	Yes	24 (57.1%)	26 (60.4%)

* Data numbers (%) or means (SD).

Table 2. Vas scores* at each time point.

		Group
		Superelastic NiTi (n = 42)		Multistranded stainless Steel (n = 43)
Time point	Description	Mean	Standard deviation	Mean	Standard deviation
0	Baseline	0	0	0	0
1	1 h	5.0	3.0	3.7	2.1
2	2 h	6.1	3.0	4.2	2.2
3	4 h	8.6	4.0	8.4	4.3
4	6 h	14.6	7.0	12.7	6.0
5	12 h	27.0	9.1	24.4	10.8
6	Day 1 morning	28.8	11.0	26.4	9.0
7	Day 1 afternoon	27.8	9.1	25.4	8.6
8	Day 1 bedtime	27.5	11.2	25.2	8.2
9	Day 2 morning	24.6	10.4	23.0	5.8
10	Day 2 afternoon	22.2	9.6	21.6	6.0
11	Day 2 bedtime	20.6	10.2	20.3	6.5
12	Day 3 morning	18.3	9.2	17.9	6.3
13	Day 3 afternoon	16.1	8.2	16.5	5.7
14	Day 3 bedtime	15.6	7.6	15.0	3.5
15	Day 4 morning	14.2	6.8	12.9	2.5
16	Day 4 afternoon	12.9	4.6	11.6	2.0
17	Day 4 bedtime	11.3	5.3	10.1	3.1
18	Day 5 morning	9.8	4.3	8.5	3.0
19	Day 5 afternoon	8.3	4.6	7.1	2.5
20	Day 5 bedtime	6.4	3.3	5.9	2.3
21	Day 6 morning	5.5	3.4	4.9	2.5
22	Day 6 afternoon	4.9	2.5	4.4	1.8
23	Day 6 bedtime	4.4	1.6	3.7	1.5
24	Day 7 morning	3.5	1.5	3.2	1.3
25	Day 7 afternoon	2.7	0.9	2.9	0.8
26	Day 7 bedtime	2.3	0.9	2.5	0.8
27	Day 10 morning	2.5	1.2	2.1	1.1
28	Day 10 afternoon	2.3	1.3	2.0	1.1
29	Day 10 bedtime	2.2	0.8	1.9	1.0
30	Day 14 morning	2.1	0.9	1.8	0.9
31	Day 14 afternoon	1.8	1.1	1.7	1.2
32	Day 14 bedtime	1.8	0.6	1.5	0.7

Table 3. Effect of superelastic NiTi versus multistranded stainless steel wires on orthodontic pain.

Effect	Numerator DF^†	Denominator DF*	F value	Pr>F
Group	1	92.63	2.65	0.1071
Time	32	2501	146.63	<0.0001
Group×Time	32	2501	1.57	0.0226

* Type III tests of fixed effects.

† Kenward Roger Degree of Freedom.

Table 4. Pairwise comparisons of superelastic NiTi versus multistranded stainless steel wires for effect on pain at each time point.

								95% confidence interval
Time	Group*		Estimate	SE^†	DF^‡	t value	P^¶	Lower	Upper
Baseline	Multistranded	Superelastic	−1.81E-13	1.1125	1047	0	1	−2.1815	2.1815
1 h	Multistranded	Superelastic	−1.3053	1.1125	1047	−1.17	0.2408	−3.4868	0.8762
2 h	Multistranded	Superelastic	−1.8545	1.1125	1047	−1.67	0.0956	−4.036	0.327
4 h	Multistranded	Superelastic	−0.245	1.1125	1047	−0.22	0.8257	−2.4266	1.9365
6 h	Multistranded	Superelastic	−1.9599	1.1125	1047	−1.76	0.0782	−4.1415	0.2216
12 h	Multistranded	Superelastic	−2.6041	1.1125	1047	−2.34	0.0193	−4.7856	−0.4226
Day 1 morning	Multistranded	Superelastic	−2.4572	1.1125	1047	−2.21	0.0273	−4.6387	−0.2757
Day 1 afternoon	Multistranded	Superelastic	−2.3516	1.1125	1047	−2.11	0.0346	−4.5331	−0.1701
Day 1 bedtime	Multistranded	Superelastic	−2.263	1.1125	1047	−2.03	0.042	−4.4445	−0.08149
Day 2 morning	Multistranded	Superelastic	−1.6196	1.1125	1047	−1.46	0.1456	−3.8011	0.5619
Day 2 afternoon	Multistranded	Superelastic	−0.6327	1.1125	1047	−0.57	0.5696	−2.8142	1.5488
Day 2 bedtime	Multistranded	Superelastic	−0.2781	1.1125	1047	−0.25	0.8026	−2.4597	1.9034
Day 3 morning	Multistranded	Superelastic	−0.3784	1.1125	1047	−0.34	0.7338	−2.5599	1.8031
Day 3 afternoon	Multistranded	Superelastic	0.4317	1.1125	1047	0.39	0.698	−1.7498	2.6132
Day 3 bedtime	Multistranded	Superelastic	−0.6619	1.1125	1047	−0.59	0.5519	−2.8434	1.5196
Day 4 morning	Multistranded	Superelastic	−1.2825	1.1125	1047	−1.15	0.2491	−3.4641	0.899
Day 4 afternoon	Multistranded	Superelastic	−1.3367	1.1125	1047	−1.2	0.2297	−3.5182	0.8448
Day 4 bedtime	Multistranded	Superelastic	−1.2189	1.1125	1047	−1.1	0.2733	−3.4005	0.9626
Day 5 morning	Multistranded	Superelastic	−1.3085	1.1125	1047	−1.18	0.2396	−3.49	0.873
Day 5 afternoon	Multistranded	Superelastic	−1.1344	1.1125	1047	−1.02	0.308	−3.3159	1.0472
Day 5 bedtime	Multistranded	Superelastic	−0.5856	1.1125	1047	−0.53	0.5987	−2.7671	1.596
Day 6 morning	Multistranded	Superelastic	−0.5915	1.1125	1047	−0.53	0.595	−2.773	1.59
Day 6 afternoon	Multistranded	Superelastic	−0.4731	1.1125	1047	−0.43	0.6707	−2.6546	1.7084
Day 6 bedtime	Multistranded	Superelastic	−0.6648	1.1125	1047	−0.6	0.5502	−2.8464	1.5167
Day 7 morning	Multistranded	Superelastic	−0.2239	1.1125	1047	−0.2	0.8405	−2.4054	1.9576
Day 7 afternoon	Multistranded	Superelastic	0.2017	1.1125	1047	0.18	0.8561	−1.9798	2.3833
Day 7 bedtime	Multistranded	Superelastic	0.2182	1.1125	1047	0.2	0.8445	−1.9633	2.3998
Day 10 morning	Multistranded	Superelastic	−0.4228	1.1125	1047	−0.38	0.7039	−2.6044	1.7587
Day 10 afternoon	Multistranded	Superelastic	−0.2619	1.1125	1047	−0.24	0.8139	−2.4434	1.9196
Day 10 bedtime	Multistranded	Superelastic	−0.2209	1.1125	1047	−0.2	0.8426	−2.4024	1.9606
Day 14 morning	Multistranded	Superelastic	−0.3202	1.1125	1047	−0.29	0.7735	−2.5017	1.8613
Day 14 afternoon	Multistranded	Superelastic	−0.1038	1.1125	1047	−0.09	0.9257	−2.2853	2.0777
Day 14 bedtime	Multistranded	Superelastic	−0.2903	1.1125	1047	−0.26	0.7941	−2.4718	1.8912

* Multistranded: multistranded stainless steel; superelastic: superelastic NiTi.

† Standard error.

‡ Kenwardroger Degree of Freedom.

¶ Significance level P<0.05.