Cephalometric evaluation of the effects of the Twin Block appliance in subjects with Class II, Division 1 malocclusion amongst different cervical vertebral maturation stages

Khoja, Aisha; Fida, Mubassar; Shaikh, Attiya

doi:10.1590/2177-6709.21.3.073-084.oar

ABSTRACT

Objectives:

To evaluate the cephalometric changes in skeletal, dentoalveolar and soft tissue variables induced by Clark's Twin Block (CTB) in Class II, Division 1 malocclusion patients and to compare these changes in different cervical vertebral maturation stages.

Methods:

Pre- and post-treatment/observation lateral cephalograms of 53 Class II, Division 1 malocclusion patients and 60 controls were compared to evaluate skeletal, dentoalveolar and soft tissue changes. Skeletal maturity was assessed according to cervical vertebral maturation stages. Pre- and post-treatment/observation mean changes and differences (T₂-T₁) were compared by means of Wilcoxon sign rank and Mann-Whitney U-tests, respectively. Intergroup comparisons between different cervical stages were performed by means of Kruskal-Wallis test and Mann-Whitney U-test (p ≤ 0.05) .

Results:

When compared with controls, there was a significant reduction in ANB angle (p < 0.001), which was due to a change in SNB angle in CS-2 and CS-3 (p < 0.001), and in SNA (p < 0.001) and SNB (p = 0.016) angles in the CS-4 group. There was significant increase in the GoGn-SN angle in CS-2 (p = 0.007) and CS-4 (p = 0.024), and increase in Co-Gn and Go-Gn amongst all cervical stages (p < 0.05). There was significant decrease in U1-SN and increase in IMPA amongst all cervical stages (p < 0.05). There was significant retraction of the upper lip in CS-3 (p = 0.001), protrusion of the lower lip in CS-2 (p = 0.005), increase in nasolabial angle in CS-4 (p = 0.006) and Z-angle in CS-3 (p = 0.016), reduction in H-angle in CS-2 (p = 0.013) and CS-3 (p = 0.002) groups. When pre- and post-treatment mean differences were compared between different cervical stages, significant differences were found for SNA, SNB and UI-SN angles and overjet. .

Conclusions:

The Twin-Block along with the normal craniofacial growth improves facial esthetics in Class II, Division 1 malocclusion by changes in underlying skeletal and dentoalveolar structures. The favorable mandibular growth occurs during any of the cervical vertebral maturation stages, with more pronounced effect during CS-3 stage.

Keywords:
Twin Block; Class II, Division 1 malocclusion; Cervical vertebral maturation

[1] Contact address: Aisha Khoja E-mail: dr.aisha86@gmail.com

Variables	Treatment group (T₁) Mean ± SD	Control group (T₁) Mean ± SD	p value
SNA	81.1 ± 3.88	81.8 ± 2.07	0.351
SNB	73.8 ± 3.41	74.7 ± 2.15	0.182
ANB	7.31 ± 1.99	7.12 ± 2.19	0.316
GoGn-SN	32.9 ± 4.63	33.9 ± 4.81	0.198
Co-A	86.7 ± 4.81	87.9 ± 5.82	0.134
Co-Gn	106.3 ± 6.92	106.3 ± 7.29	0.968
Go-Gn	67.4 ± 4.24	67.4 ± 6.70	0.266
UI-SN	109.7 ± 9.82	108.1 ± 6.45	0.109
IMPA	101.4 ± 7.16	100.2 ± 5.70	0.580
OJ (overjet)	8.37 ± 1.97	7.87 ± 2.98	0.146
UL-Eline	-0.22 ± 1.67	-0.27 ± 2.85	0.764
LL-Eline	0.83 ± 2.74	-0.01 ± 3.72	0.221
N-L angle	102.8 ± 13.3	105.6 ± 7.47	0.552
Z-angle	60.5 ± 5.68	62.3 ± 5.10	0.352
H-angle	23.7 ± 4.51	23.0 ± 3.31	0.804

Variables	Treatment group (n = 53)			Control group (n = 60)
Variables	T₁Mean ± SD	T₂Mean ± SD	p value	T₁Mean ± SD	T₂Mean ± SD	p value
Skeletal variables				T₁Mean ± SD	T₂Mean ± SD	p value
SNA	81.1 ± 3.88	80.9 ± 4.00	0.180	81.8 ± 2.07	81.9 ± 1.80	0.555
SNB	73.8 ± 3.41	75.5 ± 3.54	< 0.001**	74.7 ± 2.15	74.8 ± 2.19	0.072
ANB	7.31 ± 1.99	5.37 ± 1.99	< 0.001**	7.12 ± 2.19	6.98 ± 2.23	0.455
GoGn-SN	32.9 ± 4.63	33.5 ± 5.38	0.189	33.9 ± 4.81	33.8 ± 4.62	0.615
Co-A	86.7 ± 4.81	87.8 ± 5.06	< 0.001**	87.9 ± 5.82	88.4 ± 5.70	0.057
Co-Gn	106.3 ±6.92	110.9± 7.89	< 0.001**	106.4 ±7.29	107.7 ± 7.06	< 0.001**
Go-Gn	67.4 ± 4.24	70.8 ± 4.22	< 0.001**	67.4 ± 6.70	68.4 ± 8.63	0.206
Dentoalveolar variables				67.4 ± 6.70	68.4 ± 8.63	0.206
UI-SN	109.8 ± 9.82	105.1 ± 8.60	< 0.001**	108.1 ± 6.45	109.2 ± 9.82	0.002*
IMPA	101.4 ± 7.16	105.8 ± 6.31	< 0.001**	100.2 ± 5.70	101.3 ± 5.60	0.124
Overjet	8.37 ± 1.97	1.86 ± 1.41	< 0.001**	7.87 ± 2.98	7.56 ± 3.43	0.067
Soft tissue variables				7.87 ± 2.98	7.56 ± 3.43	0.067
UL-E-line	-0.23 ± 1.67	-1.03 ± 2.55	0.014*	-0.27 ± 2.85	-1.29 ± 1.79	0.433
LL-E-line	0.83 ± 2.74	1.21 ± 2.58	0.095	-0.00 ± 3.72	-0.56 ± 3.34	0.194
N-L angle	102.8 ± 13.3	106.4 ± 11.6	0.022*	105.6 ± 7.47	101.8 ± 10.4	0.084
Z-angle	60.5 ± 5.68	62.8 ± 7.45	< 0.001**	62.3 ± 5.10	61.3 ± 5.59	0.585
H-angle	23.7 ± 4.51	20.2 ± 3.20	< 0.001**	23.0 ± 3.31	22.8 ± 3.11	0.620

Variables	Treatment group (n = 53)	Control group (n = 60)	Treatment effect	p value
Variables	Mean ± SD	Mean ± SD	(Treatment - Control group)	p value
SNA	-0.19 ± 1.10	0.04 ± 1.01	-0.23	0.168
SNB	1.73 ± 1.22	0.17 ± 1.03	1.56	< 0.001**
ANB	-1.96 ± 1.16	-0.14 ± 1.21	-1.82	< 0.001**
GoGn-SN	0.60 ± 2.45	-0.19 ± 1.09	0.79	0.029*
Co-A	1.13 ± 2.06	0.52 ± 2.08	0.61	0.068
Co-Gn	4.58 ± 2.97	1.31 ± 2.28	3.27	< 0.001**
Go-Gn	3.45 ± 2.24	0.52 ± 2.06	2.93	< 0.001**
UI-SN	-4.66 ± 5.44	1.12 ± 4.19	-5.78	< 0.001**
IMPA	4.30 ± 3.91	1.05 ± 3.45	3.25	< 0.001**
OJ (overjet)	-6.50 ± 2.46	-0.30 ± 1.25	-6.20	< 0.001**
UL-E-line	-0.81 ± 2.41	-0.62 ± 3.47	-0.19	0.015*
LL-E-line	0.37 ± 1.57	-0.55 ± 4.24	0.92	0.082
N-L angle	3.64 ± 9.83	-3.72 ± 14.17	7.36	0.001*
Z-angle	2.30 ± 3.89	-1.07 ± 8.12	3.37	0.021*
H-angle	-3.56 ± 4.86	-0.20 ± 2.72	-3.36	< 0.001**

Variables	CS-2			CS-3			CS-4
	Mean ± SD			Mean ± SD			Mean ± SD
	TG	CG	p value	TG	CG	p value	TG	CG	p value
	n = 18	n = 20	p value	n = 22	n = 20	p value	n = 13	n = 20	p value
SNA	-0.47 ± 0.81	-0.88 ± 0.66	0.194	0.32 ± 1.28	0.58 ± 0.75	0.682	-0.69 ±0.75	0.41 ± 0.90	< 0.001**
SNB	1.44 ± 1.04	-0.39 ±1.07	< 0.001**	2.32 ± 1.28	0.73 ± 0.63	< 0.001**	1.15 ± 0.98	0.18 ± 1.03	0.016*
ANB	-1.92 ± 1.03	-0.48 ± 1.28	0.001*	-2.00 ± 1.27	-0.15 ± 1.27	< 0.001**	-1.84 ±1.21	0.23 ± 1.00	< 0.001**
GoGn-SN	0.27 ± 2.02	-0.52 ± 1.21	0.007*	0.14 ± 2.55	-0.28 ± 0.97	0.629	1.84 ± 2.57	0.23 ± 1.00	0.024*
Co-A	0.94 ± 2.71	0.07 ± 1.57	0.194	1.50 ± 1.33	0.25 ± 2.70	0.290	0.77 ± 2.12	1.24 ± 1.70	0.956
Co-Gn	3.72 ± 1.74	1.03 ± 1.93	< 0.001**	5.54 ± 3.26	1.24 ± 2.92	< 0.001**	4.15 ± 3.53	1.65 ± 1.93	0.027*
Go-Gn	3.38 ± 1.68	0.10 ± 1.57	< 0.001**	3.59 ± 2.59	0.29 ± 2.73	0.001*	3.31 ± 2.46	1.17 ± 1.62	0.004*
UI-SN	-6.72 ± 6.22	1.05 ± 6.29	< 0.001**	-1.68 ± 4.30	1.30 ± 2.90	0.013*	-6.77 ±3.51	1.00 ± 2.55	< 0.001**
IMPA	4.55 ± 4.09	1.88 ± 2.05	0.002*	3.00 ± 3.10	0.61 ± 2.38	0.005*	6.15 ± 4.35	0.67 ± 5.10	0.005*
OJ	-5.59 ± 2.96	-0.55 ± 1.41	< 0.001**	-7.25 ± 2.20	0.14 ± 1.01	< 0.001**	-6.51 ±1.73	-0.52 ± 1.24	< 0.001**
UL-E-line	0.05 ± 2.76	0.04 ± 1.54	0.597	-1.18 ± 1.10	-1.26 ± 5.64	0.001*	-1.38 ±3.25	-0.65 ± 1.54	0.096
LL-E-line	1.05 ± 1.39	-0.76 ± 2.04	0.005*	0.04 ± 1.49	-0.25 ± 7.03	0.630	0.00 ± 1.73	-0.65 ± 1.41	0.426
N-L angle	4.33 ± 9.14	-2.55 ± 15.3	0.208	2.31 ± 10.53	-1.80 ± 13.3	0.164	5.53 ± 10.9	-6.80 ± 14.4	0.006*
Z-angle	1.33 ± 3.94	-0.10 ± 5.24	0.407	2.30 ± 3.89	-1.06 ± 8.12	0.016*	2.46 ± 4.96	-0.90 ± 10.2	0.781
H-angle	-3.50 ± 3.89	-0.70 ± 3.22	0.013*	-4.54 ± 6.35	-0.40 ± 2.25	0.002*	-2.00 ±2.41	-0.30 ± 2.61	0.162

Cephalometric variables				p value^#	Multiple comparisons for the cephalometric variables
Cephalometric variables	CS-2 (n = 18) Mean ± SD	CS-3 (n = 22) Mean ± SD	CS-4 (n = 12) Mean ± SD	p value^#	CS-2/CS-3 p ^†	CS-2/CS-4 p^†	CS-3/CS-4 p^†
SNA	-0.47 ± 0.81	0.32 ± 1.28	-0.69 ± 1.73	0.010*	0.016*	0.435	0.011*
SNB	1.44 ± 1.04	2.32 ± 1.28	1.15 ± 0.98	0.020*	0.037*	0.540	0.015*
ANB	-2.00 ± 1.02	-2.00 ± 1.27	-1.84 ± 1.21	0.910	0.735	0.885	0.699
GoGn-SN	0.27 ± 2.02	0.14 ± 2.55	1.84 ± 2.57	0.096	0.339	0.266	0.026*
Co-A	0.94 ± 2.71	1.50 ± 1.33	0.77 ± 2.12	0.617	0.363	0.792	0.490
Co-Gn	3.72 ± 1.74	5.54 ± 3.26	4.15 ± 3.53	0.171	0.064	0.840	0.236
Go-Gn	3.38 ± 1.68	3.59 ± 2.59	3.31 ± 2.46	0.900	0.890	0.625	0.769
UI-SN	-7.16 ± 6.67	-1.68 ± 4.30	-6.76 ± 3.51	0.003*	0.010*	0.904	0.002*
IMPA	4.55 ± 4.09	3.00 ± 3.10	6.15 ± 4.35	0.065	0.056	0.387	0.055*
OJ	-5.59 ± 2.96	-7.25 ± 2.20	-6.52 ± 1.73	0.035*	0.018*	0.088	0.264
UL-E-line	0.05 ± 2.76	-1.18 ± 1.10	-1.38 ± 3.25	0.244	0.475	0.183	0.128
LL-E-line	1.05 ± 1.39	0.04 ± 1.49	0.00 ± 1.73	0.057	0.032*	0.057	0.696
N-L angle	4.88 ± 9.79	2.32 ± 10.53	4.92 ± 10.05	0.431	0.261	0.936	0.295
Z-angle	1.33 ± 3.94	3.00 ± 3.10	2.46 ± 4.96	0.480	0.227	0.559	0.619
H-angle	-3.50 ± 3.89	-4.54 ± 6.35	-2.00 ± 2.41	0.441	0.701	0.162	0.437