Efficiency of two protocols for maxillary molar intrusion with mini-implants

Twenty five maxillary first molars extruded for loss of their antagonists in adult subjects were selected. The sample was divided into two groups, according to the intrusion protocol with two or three mini-implants. Group 1 consisted of 15 molars that were intruded by two mini-implants. Group 2 consisted of 10 molars intruded by three mini-implants. Changes with treatment were analyzed in lateral cephalograms at the beginning and at the end of intrusion of maxillary molars.

Results:

Results showed that there was no difference in efficiency for the two intrusion protocols. It was concluded that extruded maxillary molars can be intruded with two or three mini-implants with similar efficiency.

Keywords:
Corrective Orthodontics; Tooth intrusion; Bone screws

Authorship

Juliana Volpato Curi Paccini

MSc, Universidade Cidade de São Paulo (UNICID), Department of Orthodontics, São Paulo, São Paulo, Brazil.Universidade Cidade de São PauloBrazilSão Paulo, São Paulo, BrazilMSc, Universidade Cidade de São Paulo (UNICID), Department of Orthodontics, São Paulo, São Paulo, Brazil.

Flávio Augusto Cotrim-Ferreira

Professor, Universidade Cidade de São Paulo (UNICID), Department of Orthodontics, São Paulo, São Paulo, Brazil.Universidade Cidade de São PauloBrazilSão Paulo, São Paulo, BrazilProfessor, Universidade Cidade de São Paulo (UNICID), Department of Orthodontics, São Paulo, São Paulo, Brazil.

Flávio Vellini Ferreira

Karina Maria Salvatore de Freitas

Professor, Faculdade Ingá, Department of Orthodontics, Maringá, Paraná, Brazil.Faculdade IngáBrazilMaringá, Paraná, BrazilProfessor, Faculdade Ingá, Department of Orthodontics, Maringá, Paraná, Brazil.

Rodrigo Hermont Cançado

Fabrício Pinelli Valarelli

Contact address: Karina Maria Salvatore de Freitas Av. Colombo, 9.727 Km 130 - Maringá, PR, Brazil. CEP: 87070-810 E-mail: kmsf@uol.com.br

Authors contribution Conception or design of the study: JVCP, FACF, FVF. Data acquisition, analysis or interpretation: JVCP, KMSF, RHC, FPV. Writing of the article: JVCP, KMSF, RHC. Critical revision of the article: KMSF, FACF, FVF, FPV. Final approval of the article: KMSF, FACF, RHC, FVF, FPV. Obtained funding: JVCP, FACF, FVF. Overall responsibility: JVCP.

SCIMAGO INSTITUTIONS RANKINGS

Figures | Tables

Figures (6)
Tables (6)

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Figure 1
First molar intrusion in Group 1.

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Figure 2
First molar intrusion in Group 2.

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Figure 3
Cephalometric variables: 1) SNA, 2) SNB, 3) ANB, 4) FMA, 5) SN.GoGn, 6) SN.Ocl, 7) LAFH, 8) U1.NA, 9) U1-NA, 10) U1-PP, 11) U5-PP, 12) U6-PTV, 13) U6-PP, 14) U6.SN, 15) L1.NB, 16) L1-NB, 17) L1-GoGn, 18) Overjet, 19) Overbite, 20) UL-E, 21) LL-E, 22) Nasolabial Angle.

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Figure 4
Cephalometric variables relative to the maxillary first molar: 12) U6-PTV, 13) U6-PP, 14) U6.SN.

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Figure 5
Initial and final average tracings superimposition of Group

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Figure 6
Initial and final average tracings superimposition of Group 2.

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Table 1
Intergroup comparability of initial age (independent t-test).

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Table 2
Intergroup comparability of sex distribution (Fisher exact test).

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Table 3
Intergroup comparability of type of malocclusion (Fisher exact test).

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Table 4
Intergroup comparison of cephalometric variables at the initial stage (T₁) (independent t-tests).

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Table 5
Intergroup comparison of cephalometric changes during treatment/intrusion (T₂-T₁) (independent t -ests).

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Table 6
Intergroup comparison of intrusion duration and efficiency (independent t-tests).

Figure 1 First molar intrusion in Group 1.

Figure 2 First molar intrusion in Group 2.

Figure 3 Cephalometric variables: 1) SNA, 2) SNB, 3) ANB, 4) FMA, 5) SN.GoGn, 6) SN.Ocl, 7) LAFH, 8) U1.NA, 9) U1-NA, 10) U1-PP, 11) U5-PP, 12) U6-PTV, 13) U6-PP, 14) U6.SN, 15) L1.NB, 16) L1-NB, 17) L1-GoGn, 18) Overjet, 19) Overbite, 20) UL-E, 21) LL-E, 22) Nasolabial Angle.

Figure 4 Cephalometric variables relative to the maxillary first molar: 12) U6-PTV, 13) U6-PP, 14) U6.SN.

Figure 5 Initial and final average tracings superimposition of Group

Figure 6 Initial and final average tracings superimposition of Group 2.

Table 1 Intergroup comparability of initial age (independent t-test).

Variable (Years)	Group 1		Group 2
	Mean	SD	Mean	SD	P Value
Initial age	34.25	8.22	39.47	8.12	0.131

Table 2 Intergroup comparability of sex distribution (Fisher exact test).

Sex / Group	Female	Male	Total
Group 1	12	3	15
Group 2	8	2	10
Total	20	5	25
Fisher Exact Test		DF=1	p = 1.000

Table 3 Intergroup comparability of type of malocclusion (Fisher exact test).

Type of malocclusion	Group 1 (n = 15)	Group 2 (n = 10)
Class I	8	3
Class II	7	7
Fisher Exact Test	DF=1	p = 0.413

Table 4 Intergroup comparison of cephalometric variables at the initial stage (T₁) (independent t-tests).

Variables	Group 1		Group 2		p value
Variables	Mean	SD	Mean	SD
Maxillary Component				SD
SNA (degrees)	85.18	3.20	85.56	3.81	0.7897
Mandibular Component				3.81	0.7897
SNB (degrees)	81.43	3.75	81.48	2.20	0.9681
Maxillomandibular Relationship				2.20	0.9681
ANB (degrees)	3.77	2.41	4.08	4.75	0.8328
Vertical Component				4.75	0.8328
FMA (degrees)	27.51	4.96	27.76	6.03	0.9119
SN.GoGn (degrees)	29.98	5.63	30.60	4.55	0.7744
SN.Ocl (degrees)	6.08	7.05	7.96	3.67	0.4477
LAFH (mm)	63.24	5.32	60.12	6.98	0.2174
Maxillary Dentoalveolar Component				6.98	0.2174
U1.NA (degrees)	26.01	8.00	23.61	8.19	0.4747
U1-NA (mm)	4.80	2.77	3.15	2.76	0.1572
U1-PP (mm)	26.98	3.26	24.88	3.06	0.1196
U5-PP (mm)	23.82	2.68	22.11	4.10	0.2177
U6-PTV (mm)	19.65	2.75	19.47	3.53	0.8853
U6-PP (mm)	21.58	2.83	19.79	3.17	0.1530
U6.SN (degrees)	80.81	5.30	81.00	6.92	0.9376
Mandibular Dentoalveolar Component				6.92	0.9376
L1.NB (degrees)	27.33	5.94	22.34	5.94	0.0514
L1-NB (mm)	5.83	2.22	3.98	2.26	0.0548
L1-GoGn (mm)	37.45	2.47	37.11	3.94	0.7944
Dental Relationships				3.94	0.7944
Overjet (mm)	3.84	1.11	4.32	2.71	0.5437
Overbite(mm)	2.99	0.94	3.49	2.38	0.4717
Soft Tissue Component				2.38	0.4717
UL-E (mm)	-3.75	2.43	-4.24	3.84	0.6965
LL-E (mm)	-1.21	2.40	-1.65	2.96	0.6835
Nasolabial angle (degrees)	100.56	7.45	103.48	11.60	0.4495

Table 5 Intergroup comparison of cephalometric changes during treatment/intrusion (T₂-T₁) (independent t -ests).

Variables	Group 1		Group 2		p value
Variables	Mean	SD	Mean	SD
Maxillary Component				SD
SNA (degrees)	0.06	1.42	0.36	1.43	0.6104
Mandibular Component				1.43	0.6104
SNB (degrees)	-0.09	1.27	0.48	0.90	0.2295
Maxillomandibular Relationship				0.90	0.2295
ANB (degrees)	0.13	0.99	-0.11	1.33	0.6134
Vertical Component				1.33	0.6134
FMA (degrees)	-0.47	1.60	-1.24	0.98	0.1863
SN.GoGn (degrees)	0.34	1.27	-0.57	1.20	0.0864
SN.Ocl (degrees)	4.81	3.66	3.44	3.39	0.3539
LAFH (mm)	-0.16	2.11	0.16	1.80	0.6978
Maxillary Dentoalveolar Component				1.80	0.6978
U1.NA (degrees)	2.33	4.98	2.13	7.76	0.9368
U1-NA (mm)	0.52	1.88	-0.12	1.97	0.4215
U1-PP (mm)	-0.59	3.23	1.73	9.32	0.3808
U5-PP (mm)	-1.39	1.90	-1.31	1.67	0.9183
U6-PTV (mm)	-0.08	2.66	0.50	2.62	0.5963
U6-PP (mm)	-1.79	1.28	-2.12	1.25	0.5253
U6.SN (degrees)	1.17	3.29	-0.42	5.02	0.3458
Mandibular Dentoalveolar Component				5.02	0.3458
L1.NB (degrees)	2.51	2.80	0.21	4.07	0.1059
L1-NB (mm)	0.33	0.95	0.15	1.13	0.6761
L1-GoGn (mm)	-0.75	1.18	-0.37	1.42	0.4780
Dental Relationships				1.42	0.4780
Overjet (mm)	0.55	1.32	-0.51	2.23	0.1484
Overbite(mm)	-1.49	1.24	-1.57	2.46	0.9117
Soft Tissue Component				2.46	0.9117
UL-E (mm)	0.30	1.98	-0.13	2.24	0.6188
LL-E (mm)	1.11	1.02	-0.65	2.65	0.0275*
Nasolabial angle (degrees)	-1.07	8.92	-4.44	8.73	0.3601

^*
Statistically significant for p < 0.05

Table 6 Intergroup comparison of intrusion duration and efficiency (independent t-tests).

Variables	Group 1		Group 2		P Value
Variables	Mean	SD	Mean	SD	P Value
Intrusion duration (years)	0.81	0.35	1.17	0.48	0.045*
Intrusion efficiency	-2.18	1.14	-1.86	1.07	0.489

^*
Statistically significant for p < 0.05.

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Efficiency of two protocols for maxillary molar intrusion with mini-implants

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[1] Contact address: Karina Maria Salvatore de Freitas Av. Colombo, 9.727 Km 130 - Maringá, PR, Brazil. CEP: 87070-810 E-mail: kmsf@uol.com.br