Material and methods

A total sample of 48 (16 per group) was required for a power of 85% at the 5% significance level. Sample size estimation was performed using PASS 2000 software (NCSS LLC, Caysville, Utah).

Fifty-one patients from orthodontic department of Başkent University, Ankara, Turkey, were included in this study. All subjects were between PP2= and MP3cap developmental stages at the initial observation (T1) according to their hand-wrist radiographs. The first 2 groups were constituted prospectively and compared in a retrospective manner.

The inclusion criteria were (1) skeletal and dental Class III malocclusion with maxillary deficiency (ANB, <0°; Nperp-A, <0 mm) and retrusive nasomaxillary complex with or without mandibular prognathia, (2) vertically normal or low growth pattern (SNGoGn, <40°), (3) anterior crossbite and Angle Class III molar relationship, and (4) normal or increased overbite. All subjects and parents were informed of the surgical procedure and signed an informed consent form, and the study was approved by the ethics committee of Başkent University, with the project numbers D-KA06/07 and D-KA10/04.

All patients were treated by 2 operators (C.S. and Z.S.) at the same university clinic until 4 to 5 mm of overjet was achieved. Before maxillary protraction in the treatment groups, a bonded RME appliance was applied, and the expansion screw (1114/10; Lewa-Dental, Remchingen, Germany) was activated twice a day for a week until the midpalatal suture was disturbed. The expansion was continued with a semirapid protocol (RME for 7 days, followed by slow maxillary expansion) in patients who still had a transverse deficiency, until adequate expansion was achieved. The major goal of applying the RME appliance is to disrupt the circummaxillary sutures and stimulate forward displacement of the maxilla.

Group 1 (n = 17) consisted of patients treated with a miniplate-anchored orthopedic facemask. In each patient, 2 miniplates were inserted in the lateral nasal walls of the maxilla, and the facemasks were applied from 2 titanium miniplates (OsteoMed, Addison, Tex). An incision was made at the labial vestibule between the maxillary lateral incisors and canines, and a mucoperiosteal flap was elevated to expose the lateral nasal wall of the maxilla on both sides. The miniplates were adapted according to the anatomic shape of the apertura piriformis area and fixed in place with 2 monocortical miniscrews. Then the incisions were sutured with 3.0 polyglactin 910, exposing the third hole into the oral cavity ( Fig 1 ). After soft-tissue healing for 7 days, extraoral elastics of 400 g were applied from the miniplates to the facemasks ( Figs 2 and 3 ). The patients were asked to replace the elastics once a day and to wear the facemasks at least 16 hours a day.

Surgical procedure in group 1, fixation of 2 titanium miniplates to the lateral nasal walls of the maxilla: A, mucoperiosteal incisions made at the labial vestibule of the maxilla on both sides; B and C, adaptation and fixation of miniplates to lateral nasal walls of the maxilla; D, sutures exposing the third hole into the oral cavity before maxillary protraction.

A, Intraoral frontal view of miniplates; B, extraoral frontal view of the application of a facemask via miniplates; C, profile view of a patient with a facemask.

Schematic illustration of the facemask with miniplates application.

Group 2 (n = 17) was treated with Class III intermaxillary elastics from 2 titanium miniplates (55.MAN.003; Trimed, Ankara, Turkey) placed in the symphyseal region to a bonded RME appliance. The triangular-shaped titanium miniplates, used for orthodontic anchorage with 3 holes, were placed under local anesthesia. An incision was made at the labial vestibule between the mandibular lateral incisors and canines, and a mucoperiosteal flap was elevated to expose the cortical bone between the lateral incisor and the canine. It is crucial not to damage the roots of the permanent canines. Miniplates were shaped according to the anatomic structures, and the extensions of the miniplates were bent mesially to apply Class III elastics. The miniplates were fixed with 3 monocortical miniscrews. The incisions were sutured with 3.0 polyglactin 910, exposing the attachment arm through the attached gingiva near the mucogingival junction.

After a week to allow soft-tissue healing, 500 g of protraction force was applied with elastics from the extensions of the miniplates to the hooks of the bonded maxillary expansion appliance ( Figs 4 and 5 ). The patients were instructed to maintain good oral hygiene and wear the elastics 24 hours per day.

Intraoral view of the application of Class III elastics from symphyseal miniplates to a bonded expansion appliance in group 2.

Schematic illustration of the Class III elastics from the symphyseal miniplates.

All surgical procedures in groups 1 and 2 were done by the same oral surgeon (S.U.).

In order to differentiate the treatment changes from normal growth changes, the third group was the untreated control group (n = 17). These subjects were matched to those in the treatment groups.

Lateral cephalograms were obtained at T1 and at the end of protraction therapy or the observation period (T2) in all groups. All cephalograms were hand traced and measured on a conventional light box by the same investigator (Z.S.), who repeated the measurements at 3-week intervals to ensure measurement accuracy using paired t tests. Horizontal and vertical reference planes were used to make the linear measurements. The horizontal reference plane was constructed by subtracting 7° from the sella-nasion line, and a vertical line passing through sella and perpendicular to the horizontal reference plane was used as the vertical reference plane.

Lateral cephalometric radiographs obtained at T2 were superimposed on those at T1 by means of the total structural superimposition method as described by Bjork and Skieller. In addition, maxillary and mandibular regional superimpositions were done to measure the movement of the maxillary and mandibular dentitions relative to their basal bones. Maxillary regional superimpositions were made on the best fit of the lingual curvature of the palatal plate and internal bony structures. A maxillary horizontal line was defined as the line drawn along the anterior nasal spine and the posterior nasal spine, and a vertical line passing through posterior nasal spine and perpendicular to the maxillary horizontal line was used as the maxillary vertical line. Mandibular superimpositions were made on stable mandibular structures. A line passing through gonion and gnathion was used as the mandibular horizontal line, and the mandibular vertical line was defined as the line passing through gonion and perpendicular to the mandibular horizontal line. The degree of mandibular rotation was evaluated by measuring the angle between the sella-nasion lines of T1 and T2 radiographs on the superimposed tracings.

Cephalometric landmarks, reference planes, and measurements are shown in Figures 6 through 8 .

Maxillary and mandibular skeletal measurements: 1 , SNA, the angle between the SN and NA planes; 2 , A-VR, the distance between Point A and the vertical reference plane; 3 , Nperp-A, the distance from Point A to the nasion perpendicular plane; 4 , HR.PP, the angle between the palatal and horizontal reference planes; 5 , SNB, the angle between the SN and NB planes; 6 , B-VR, the distance between Point B and the vertical reference plane; 7 , Nperp-Pg, the distance from pogonion to the nasion perpendicular plane; 8 , Pg-VR, the distance between pogonion and the vertical reference plane; 9 , SN.GoGn, the angle between the SN and GoGn planes; 10 , HR.GoMe, the angle between the horizontal reference and mandibular planes.

Vertical skeletal, maxillomandibular, and soft-tissue measurements: 11 , N-Me, the distance between nasion and menton; 12 , ANS-Me, the distance between the anterior nasal spine and menton; 13 , ANB, the angle between the NA and NB planes; 14 , Wits appraisal, the distance between the perpendicular projections of Points A and B to the occlusal plane; 15 , U1.PP, the angle between the axis of the maxillary central incisor and the palatal plane; 16 , L1.MP, the angle between the axis of the mandibular central incisor and the mandibular plane; 17 , Sn-Me′, the distance between subnasale and soft-tissue menton; 18 , UL-VR, the distance between the most forward point of the upper lip in the sagittal dimension to the vertical reference plane; 19 , LL-VR, the distance between the most forward point of the lower lip in the sagittal dimension to the vertical reference plane; 20 , Pg′-VR, the distance between soft-tissue pogonion and the vertical reference plane.

Maxillary and mandibular dentoalveolar measurements: 21 , U1.HRmx, the angle between the axis of the maxillary central incisor and the maxillary horizontal reference plane; 22 , U6-VRmx, the distance from the mesiobuccal tubercule of the maxillary first molar to the maxillary vertical reference plane; 23 , L1.HRmd, the angle between the axis of the mandibular central incisor and the mandibular horizontal reference plane.

Results

There were no statistically significant differences between the groups at T1 for the analyzed parameters. Table II shows the mean values of the measurements at T1 and the comparison of the 3 groups. The differences between the changes from T2 to T1 in all groups are shown in Table III .

Table III

Changes in the groups with the significance in each group and comparison of changes in the groups (T2-T1)

Parameter	MP+FM (Group 1) Mean ± SD Median (range)	P	MP+CI III Elastics (Group 2) Mean ± SD Median (range)	P	P	Control Mean ± SD Median (range)	P	1-2	1-3	1-4	2-3	2-4	3-4
Chronologic age (y)	11.23 ± 1.48		11.25 ± 1.52			9.87 ± 1.20		NS	NS	∗	NS	∗	NS
Maxillary skeletal parameters
SNA (°)	3.14 ± 1.25	‡	3.14 ± 1.15	‡	‡	0.29 ± 1.43	NS	NS	∗	‡	∗	‡	†
	3.00 (1.00-5.00)		3.00 (1.50-5.50)			0.50 (−2.50-3.00)
A-VR (mm)	3.11 ± 0.94	‡	3.82 ± 1.45	‡	‡	0.32 ± 0.95	NS	NS	†	‡	‡	‡	‡
	3.00 (1.50-5.00)		3.50 (1.50-7.00)			0.50 (−2.00-2.00)
Protraction rate (mm/mo)	0.43 ± 0.15		0.53 ± 0.25			0.03 ± 0.14		NS	†	‡	†	‡	∗
	0.41 (0.17-0.75)		0.54 (0.16-1.00)			0.05 (−0.29-0.40)
Nperp-A (mm)	3.14 ± 0.98	‡	3.94 ± 1.26	‡	‡	−0.5 ± 0.93	∗	NS	∗	‡	†	‡	‡
	3.50 (1.00-4.00)		3.50 (2.00-6.50)			−0.5 (−2.50-1.50)
HR.PP (°)	−1.08 ± 1.25	†	−2.55 ± 0.96	‡	‡	−0.26 ± 0.56	NS	†	∗	∗	NS	‡	‡
	−1.00 (−4.00-1.00)		−3.00 (−4.50-1.00)			0.00 (−1.00-0.50)
Mandibular skeletal parameters
SNB (°)	−2.44 ± 1.04	‡	−2.91 ± 0.81	‡	‡	1.08 ± 1.03	†	NS	NS	‡	NS	‡	‡
	−2.00 (−5.00- −1.00)		−3.00 (−4.50- −2.00)			1.00 (−1.00-3.00)
B-VR (mm)	−3.26 ± 1.96	‡	−4.20 ± 1.58	‡	‡	1.65 ± 1.04	‡	NS	NS	‡	NS	‡	‡
	−3.00 (−7.00-1.00)		−4.50 (−7.00- −1.00)			2.00 (−1.00-3.00)
Nperp-Pg (°)	−3.05 ± 2.53	‡	−3.41 ± 2.04	‡	‡	0.88 ± 1.06	†	NS	NS	‡	NS	‡	‡
	−3.50 (−7.00-2.50)		−3.00 (−8.00-0.50)			1.00 (−0.50-3.00)
Pg-VR (mm)	−3.29 ± 2.01	‡	−4.20 ± 1.64	‡	‡	2.02 ± 1.13	‡	NS	NS	‡	NS	‡	‡
	−3.50 (−6.00-2.00)		−4.50 (7.00- −1.00)			2.50 (−1.00-3.50)
SN.GoGn (°)	1.29 ± 1.04	‡	2.44 ± 0.68	‡	‡	−0.88 ± 0.97	†	†	‡	‡	NS	‡	‡
	1.50 (−2.00-2.50)		2.50 (1.50-4.00)			−1.00 (–3.00-1.00)
HR.GoMe (°)	1.23 ± 1.43	†	2.29 ± 1.10	‡	‡	−0.76 ± 0.58	†	∗	†	‡	NS	‡	‡
	1.00 (−1.00-4.00)		3.00 (0.00-4.00)			−1.00 (−2.00-0)
Facial heights
N-Me (mm)	2.52 ± 1.65	‡	4.41 ± 1.66	‡	‡	∗		†	NS	∗	NS	‡	‡
	2.00 (1.00-7.00)		5.00 (1.50-7.50)			1.50 (–2.00-2.50)
ANS-Me (mm)	2.61 ± 1.61	‡	4.23 ± 1.68	‡	†	0.14 ± 1.08	NS	∗	NS	‡	NS	‡	‡
	2.50 (−1.00-5.00)		4.00 (1.50-7.50)			0.50 (−3.00-1.50)
Maxillomandibular parameters
ANB (°)	5.52 ± 1.56	‡	6.05 ± 1.24	‡	‡	−0.79 ± 1.01	†	NS	∗	‡	†	‡	‡
	6.00 (2.50-7.50)		6.00 (4.00-8.00)			−1.00 (−2.50-1.00)
Wits (mm)	7.08 ± 1.60	‡	10.52 ± 2.24	‡	‡	−1.05 ± 1.57	∗	‡	NS	‡	†	‡	‡
	7.50 (4.00-9.50)		10.00 (7.50-16.00)			−1.5 (−3.00-2.00)
Dentoalveolar parameters
Overjet (mm)	7.79 ± 1.09	‡	6.61 ± 1.08	‡	‡	−0.14 ± 0.52	NS	∗	NS	‡	∗	‡	‡
	7.5 (6.00-10.00)		7.00 (4.50-8.50)			0.00 ( – 1.00-1.00)
Overbite (mm)	−1.29 ± 1.75	NS	−4.29 ± 2.31	‡	†	0.61 ± 0.85	∗	†	NS	‡	†	‡	‡
	−1.50 (−4.50-2.50)		−4.00 (−7.50- −1.00)			0.50 (−1.00-3.00)
U1.HRmx (°)	0.14 ± 3.13	NS	3.76 ± 3.07	‡	∗	2.1 ± 1.76	‡	†	NS	NS	NS	NS	NS
	−1.00 (−7.00-5.00)		3.50 (0.00-9.00)			3.00 (0.00-5.00)
U1.PP (°)	−0.05 ± 4.72	NS	4.50 ± 3.12	‡	∗	1.91 ± 1.68	‡	†	NS	NS	NS	NS	NS
	1.00 (−10.00-7.00)		4.00 (0.00-11.00)			2.00 (−0.50-5.00)
U6-VRmx (mm)	0.17 ± 0.39	NS	4.50 ± 1.15	‡	‡	0.23 ± 1.03	NS	‡	‡	NS	†	‡	‡
	0.00 (−0.50-1.00)		4.50 (2.50-7.00)			0.50 (−2.00-2.00)
L1.HRmd (°)	−6.91 ± 3.49	‡	9.23 ± 2.86	‡	‡	0.23 ± 2.40	NS	‡	NS	‡	‡	†	†
	−6.00 (−13.00-0.00)		9.00 (4.00-16.00)			0.00 (−4.00-4.00)
L1.MP (°)	−6.08 ± 3.35	‡	8.23 ± 2.81	‡	†	−0.14 ± 2.14	NS	‡	NS	‡	‡	†	†
	−5.00 (12.00- −1.00)		8.00 (3.50-15.00)			0.00 (−4.00-3.00)
Soft-tissue parameters
Sn-Me′ (mm)	2.29 ± 2.22	†	4.08 ± 1.80	‡	‡	0.14 ± 1.56	NS	†	NS	†	NS	‡	‡
	2.00 (−3.00-6.00)		4.00 (0.50-7.00)			0.00 (−3.50-2.00)
UL-VR (mm)	3.55 ± 1.49	‡	3.61 ± 1.86	‡	†	1.08 ± 1.00	†	NS	∗	‡	∗	‡	∗
	3.50 (1.00-7.00)		3.50 (1.00-7.50)			1.00 (−1.00-3.00)
LL-VR (mm)	−1.50 ± 1.88	†	−1.55 ± 2.17	†	‡	1.79 ± 1.07	‡	NS	NS	‡	NS	‡	‡
	−1.50 (−5.50-1.50)		−2.00 (−6.00-3.00)			2.00 (0.00-4.50)
Pg′-VR (mm)	−3.05 ± 2.03	‡	−3.29 ± 1.93	‡	‡	2.02 ± 099	‡	NS	NS	‡	NS	‡	‡
	−3.00 (−6.50-0.50)		−4.00 (−5.50-1.00)			2.00 (0.00-3.50)

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