Material and methods

Forty-five subjects from the Department of Orthodontics, Faculty of Dentistry, University of Başkent in Ankara, Turkey, were included in this study. All subjects were between the PP2 = and MP3cap developmental stages at the beginning of the treatment or the control period according to their hand-wrist radiographs. The patients were selected by the following inclusion criteria: (1) skeletal and dental Class III malocclusion with maxillary deficiency (ANB, <0°; Nperp-A, <1 mm; Wits apprasial, <–2 mm); (2) vertically normal growth pattern (SNGoGn, <40°); (3) anterior crossbite and Angle Class III molar relationship; and (4) normal or increased overbite and retrusive nasomaxillary complex. All subjects and parents were informed of the experimental protocols and signed an informed consent form that was previously approved by the ethics committee of the University of Başkent. The selected patients were divided into 3 groups of 15 patients each.

In the first group (MP+FM) consisting of 5 girls and 10 boys (mean age, 10.91 years), facemasks were applied from 2 titanium miniplates (OsteoMed, Addison, Tex) surgically placed laterally to the apertura piriformis regions of the maxilla. Subjects without anchorage teeth for the application of facemask, depending on congenitalIy missing teeth or early removal of posterior deciduous teeth, were given priority for inclusion in this group. I-shaped titanium miniplates, used for fixation in maxillofacial surgery, with 3 holes were placed by the same maxillofacial surgeon (S.U.) under local or general anesthesia. A mucoperiosteal 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. An appropriate cortical bone area was found to adapt the miniplates around the apertura piriformis, and special care was taken not to damage the erupting canines. Miniplates were then shaped according to the anatomic structures and fixed in position with 2 monocortical miniscrews (diameter, 1.5 mm; length, 7 mm). The incisions were sutured with 3.0 polyglactin 910 exposing the third hole into the oral cavity ( Fig 1 ). After a 1-week period to allow soft-tissue healing, protraction forces were applied with elastics from the hooks of the miniplates to the facemasks ( Fig 2 ).

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 view of the miniplates placed laterally to the apertura piriformis; B, extraoral frontal view of the application of a facemask via miniplates; C, profile view of the patient with a facemask.

The second group (FM) of 7 girls and 8 boys (mean age, 10.31 years) received maxillary protraction therapy with conventional facemasks applied from the hooks of the rapid maxillary expansion (RME) appliance.

To distinguish the treatment changes from normal growth changes, the third group of 8 girls and 7 boys (mean age, 10.05 years) was the untreated Class III control group. The subjects of the control group matched those in the treatment groups with regard to chronologic age, skeletal development, and craniofacial morphology.

Before maxillary protraction, a bonded RME appliance with hooks was applied in both treatment groups. The midline expansion screw (1114/10, Lewa, Remchingen, Germany) of the RME appliance was activated twice per day for 7 days until the midpalatal suture was disturbed, and expansion was continued with a semirapid protocol (RME of 7 days, followed by slow maxillary expansion) in patients with continuing maxillary transverse deficiency until the desired expansion was achieved. Immediately after the maxillary sutural system was disrupted, the patients were given Petit-type facemasks (716-0001, Ormco, Glendora, Calif). The facemask protocol was the same for both treatment groups. Elastics, directed 20° to 30° downward from the occlusal plane, delivered a force of 400 g per side, as determined by a force gauge. The patients were instructed to wear their facemasks at least 16 hours per day, and facemask therapy was continued until at least a 4-mm overjet was achieved. Later, all patients had retention treatment with facemasks or chincaps, and some were treated with fixed appliances subsequently.

Lateral cephalometric films were obtained at the start of the maxillary protraction or the observation period (T1) and at the end of the active treatment or the observation period (T2) in all groups and were hand-traced on orthodontic tracing paper on a conventional light box by using a 0.3-mm lead pencil and measured by the same investigator (Ç.Ş.) under optimal conditions. For the evaluation of the lateral cephalometric radiographs, in addition to the conventional reference planes, horizontal (HR) and vertical (VR) reference planes were constructed for some linear and angular measurements. A horizontal line constructed by subtracting 7° from the sella-nasion line was used as the HR plane. A vertical line passing through sella and perpendicular to the HR plane was the VR plane ( Figs 3-5 ). The lateral cephalometric radiographs taken at T2 were superimposed on those taken at T1, on stable cranial structures, by using the total structural superimpositioning method. These reference structures were the contours of the anterior wall of sella turcica, the anterior contours of the median cranial fossa, the intersection of the anterior contour of sella and tuberculum sella, the inner surface of the frontal bone, the contours of the cribriform plate, the contours of the bilateral fronto-ethmoidal crests, and the contour of the median border of the cerebral surfaces of the orbital roofs. The HR and VR planes were transferred from the T1 to the T2 radiographs. The sensitivity values of the linear and angular radiographic measurements were 0.5 mm and 0.5°, respectively.

Maxillary and maxillomandibular skeletal measurements used in the study: 1 , SNA (°); 2 , HR-ANS (mm); 3 , HR-PNS (mm); 4 , HR.PP (°); 5 , Cd-A (mm); 6 , A-VR (mm); 7 , Nperp-A (mm); 8 , ANB (°); 9 , (A-VR)-(B-VR) (mm); 10 , Wits (mm).

Mandibular skeletal measurements and facial heights used in the study: 1 , SNB (°); 2 , Cd-Gn (mm); 3 , B-VR (mm); 4 , Pg-VR (mm); 5 , Nperp-Pg (mm); 6 , HR.GoMe (°); 7 , SN.GoGn (°); 8 , BaNa.PtGn (°); 9 , S-Go (mm); 10 , N-ANS (mm); 11 , ANS-Me (mm); 12 , N-Me (mm); 13 , S-Go/N-Me.

Soft-tissue and dentoalveolar measurements used in the study: 1 , A′-VR (mm); 2 , UL-VR (mm); 3 , LL-VR (mm); 4 , B′-VR (mm); 5 , Pg′-VR; 6 , Sn-Me′ (mm); 7 , N′-Me′ (mm); 8 , U1.PP (°); 9 , L1.MP (°).

Maxillary regional superimpositions were used to measure the movement of the maxillary dentition relative to the maxillary basal bone. The maxillae were superimposed on the best fit of the lingual curvature of the palatal plate and internal bony structures. To examine the changes in the maxillary dentoalveolar structures, a maxillary HR line (HRmx) was drawn along the ANS-PNS line, and a vertical line passing through PNS and perpendicular to the HRmx was the maxillary VR plane (VRmx) ( Fig 6 ).

Maxillary dentoalveolar measurements with local superimpositions: 1 , U1.HRmx (°); 2 , U6-HRmx (mm); 3 , U6-VRmx (mm); 4 , U1i-HRmx (mm); 5 , U1i-VRmx.

Mandibular regional superimpositions were made on mandibular stable structures, according to the method described by Björk and Skieller. The 2 radiographs were superimposed on the anterior contour of the chin, the inner contour of the cortical plate at the lower border of the symphysis, the trabecular structures inside the symphysis, the contour of the mandibular canal, and the lower contour of a mineralized molar germ before root development begins. To evaluate the changes, a line passing through gonion and gnathion was used as the mandibular HR plane (HRmp), and a vertical line passing through gonion, perpendicular to the HRmp served as the mandibular VR plane (VRmp). The degree of mandibular rotation was assessed by measuring the angle between the sella-nasion lines of the first and second radiographs on the superimposed tracings ( Fig 7 ).

Mandibular dentoalveolar measurements with local superimpositions and true mandibular rotation: 1 , L1i-VRmd (mm); 2 , L1i-HRmd (mm); 3 , L1.HRmd (°); 4 , true mandibular rotation (°).

Cephalometric landmarks, reference planes and lines, and measurements are shown in Figures 3 through 7 .

Results

Mobility was noted in 8 of the 30 miniplates at T2; however, only 2 were replaced with additional surgeries during the protraction therapy. The other 6 miniplates showed minimal mobility and were rigid enough to withstand the protraction forces, so they were used until the end of the treatment. Since 2 of the 30 miniplates needed to be replaced, the success rate was 93%.

Table I gives initial values of the 3 groups. There were no significant differences between the groups at T1. The differences between the changes through T2 to T1 in the MP+FM, FM, and control groups are shown in Table II .

Table II

Changes in the groups, with the significance of changes in each group (Wilcoxon test) and comparison of changes in the groups wth the Kruskal-Wallis and Dunn tests

	MP + FM (1)		FM (2)		Control (3)
	Mean ± SD		Mean ± SD		Mean ± SD
Parameter	Median (range)	P	Median (range)	P	Median (range)	P	H	1-2	2-3	1-3
Treatment duration(y)	0.56 ± 0.16	‡	0.78 ± 0.26	‡	0.63 ± 0.10	‡
	0.50 (0.30-0.80)		0.80 (0.40-1.30)		0.60 (0.50-0.80)
Protraction rate(mm/mo)	0.45 ± 0.20		0.24 ± 0.18		0.05 ± 0.08			‡	‡	‡
	0.41 (0.17-0.83)		0.20 (0.00-0.62)		0.05 (−0.08-0.27)
Maxillary skeletal parameters
SNA (°)	2.53 ± 1.24	†	1.83 ± 1.33	†	0.26 ± 0.53	NS		‡	‡	‡
	2.00 (1.00-5.50)		2.00 (0.00-4.00)		0.00 (−1.00-1.00)
A-VR (mm)	2.83 ± 0.93	†	2.16 ± 1.38	†	0.44 ± 0.69	∗		‡	‡	‡
	3.00 (1.50-5.00)		2.00 (0.00-5.00)		0.50 (−0.50-2.00)
Cd-A (mm)	3.26 ± 1.82	†	1.80 ± 1.70	†	0.80 ± 0.95	†		‡	‡	‡
	3.00 (1.00-8.50)		1.50 (−1.50-6.00)		1.00 (−0.50-3.50)
NPerp-A (mm)	2.53 ± 1.31	†	1.76 ± 1.36	†	0.30 ± 0.59	NS		‡	‡	‡
	2.00 (0.50-4.50)		1.50 (0.00-4.00)		0.00 (−1.00-1.50)
HR-ANS (mm)	0.66 ± 1.24	∗	1.00 ± 0.98	†	0.94 ± 0.91	†	NS
	0.50 (−1.00-4.00)		1.00 (−1.50-2.00)		0.50 (−0.50-2.50)
HR-PNS (mm)	1.50 ± 0.65	†	2.24 ± 1.19	†	0.80 ± 0.84	†		‡	‡	‡
	1.50 (0.50-3.00)		2.00 (0.00-4.00)		0.50 (0.00-2.50)
HR.PP (°)	0.91 ± 1.82	NS	1.63 ± 1.51	†	−0.20 ± 1.19	NS		‡	‡	‡
	1.00 (−3.00-4.00)		1.00 (−1.00-5.00)		0.00 (−2.50-1.50)
Mandibular skeletal parameters
SNB (°)	−1.93 ± 2.19	∗	−2.30 ± 1.23	†	0.65 ± 0.65	†		∗	‡	‡
	−2.50 (−5.00-2.50)		−2.50 (−4.00-0.50)		0.50 (0.00-2.00)
B-VR (mm)	−2.76 ± 2.01	†	−3.03 ± 1.92	†	1.23 ± 1.27	†		NS	‡	‡
	−2.50 (−5.50-0.50)		−3.50 (−6.00-1.00)		1.50 (−1.00-3.50)
Cd-Gn (mm)	−0.30 ± 2.15	NS	0.43 ± 2.15	NS	1.86 ± 1.12	†		†	‡	‡
	0.00 (−5.00-3.00)		0.50 (−3.00-4.00)		2.00 (0.50-4.50)
NPerp-Pg (mm)	−2.80 ± 2.67	†	−2.90 ± 3.97	∗	0.96 ± 1.66	∗		NS	‡	‡
	−3.00 (−7.00-2.50)		−2.50 (−9.00-4.00)		0.50 (−2.00-5.00)
Pg-VR (mm)	−2.53 ± 2.10	†	−3.36 ± 2.51	†	1.93 ± 1.32	†		†	‡	‡
	−2.50 (−6.00-2.00)		−3.50 (−7.00-1.00)		2.00 (0.00-4.50)
SN.GoGn (°)	1.46 ± 2.78	∗	3.06 ± 2.07	†	−0.40 ± 0.87	NS		‡	‡	‡
	2.00 (−6.00-4.50)		3.00 (−1.00-6.00)		0.00 (−2.00-1.00)
HR.GoMe (°)	1.86 ± 2.10	†	2.76 ± 1.98	†	−0.03 ± 0.83	NS		†	‡	‡
	2.50 (−3.00-5.00)		2.50 (0.00-7.50)		0.00 (−1.00-2.00)
BaNa.PtGn (°)	−1.90 ± 2.14	∗	−3.13 ± 2.48	†	0.53 ± 0.81	∗		†	‡	‡
	−2.50 (−4.00-5.00)		−3.00 (−7.00-2.00)		0.00 (0.00-2.50)
Mandibular rotation (°)	1.83 ± 2.19		2.80 ± 2.23		−0.20 ± 1.42			†	‡	‡
	3.00 (−4.00-4.00)		3.00 (−3.00-6.00)		0.00 (−3.00-2.00)
Facial heights
S-Go (mm)	0.36 ± 1.26	NS	1.23 ± 1.98	∗	1.06 ± 1.29	†	NS
	0.00 (−1.50-3.00)		1.00 (−2.00-6.00)		1.00 (−1.00-3.50)
N-Me (mm)	2.73 ± 2.76	∗	4.63 ± 1.96	†	0.83 ± 1.01	∗		‡	‡	‡
	3.50 (−5.50-5.00)		4.00 (2.00-9.00)		1.00 (−1.50-3.00)
ANS-Me (mm)	2.10 ± 1.79	†	3.96 ± 1.74	†	0.10 ± 0.91	NS		‡	‡	‡
	2.00 (−2.00-5.00)		4.00 (0.50-7.00)		0.00 (−2.00-1.50)
N-ANS (mm)	0.56 ± 2.29	NS	0.70 ± 1.29	NS	0.76 ± 0.86	†	NS
	1.00 (−3.50-4.00)		0.50 (−1.00-3.00)		0.50 (−0.50-2.50)
S-Go/N-Me	−0.01 ± 0.02	∗	−0.01 ± 0.01	†	0.00 ± 0.01	NS		NS	‡	‡
	−0.02 (−0.05-0.03)		−0.01 (−0.04-0.01)		−0.01 (−0.05-0.03)
Maxillomandibular parameters
ANB (°)	4.46 ± 1.95	†	4.20 ± 1.96	†	−0.38 ± 0.71	NS		NS	‡	‡
	4.00 (1.00-9.00)		5.00 (0.00-7.50)		−0.30 (−1.50-0.50)
(A-VR)-(B-VR) (mm)	5.66 ± 2.24	†	5.06 ± 2.16	†	−0.78 ± 1.22	∗		NS	‡	‡
	5.50 (1.50-10.00)		5.00 (0.50-8.50)		−0.50 (−3.50-1.20)
Wits (mm)	5.43 ± 1.69	†	6.56 ± 2.88	†	−0.53 ± 1.14	NS		†	‡	‡
	5.00 (3.00-9.00)		7.00 (1.00-11.50)		−0.50 (−2.00-1.50)
Dentoalveolar parameters
Overjet (mm)	7.66 ± 1.61	†	7.93 ± 1.65	†	−0.33 ± 0.72	NS		NS	‡	‡
	8.00 (4.00-10.00)		7.50 (5.00-11.50)		−0.50 (−2.00-1.00)
Overbite (mm)	0.33 ± 2.17	NS	−0.90 ± 1.64	NS	0.26 ± 0.62	NS	NS
	−0.50 (−2.00-5.50)		−0.50 (−5.00-1.50)		0.00 (−1.00-1.50)
U1i-VRmx (mm)	−0.30 ± 1.37	NS	1.86 ± 1.32	†	0.53 ± 0.85	∗		‡	‡	‡
	0.00 (−4.00-1.00)		−2.00 (−1.00-4.00)		0.00 (0.00-2.50)
U1i-HRmx (mm)	0.66 ± 0.97	∗	0.43 ± 0.86	NS	0.33 ± 0.44	∗	NS
	0.50 (−1.00-2.50)		0.50 (−1.00-2.00)		0.00 (0.00-1.50)
U1.HRmx (°)	−2.36 ± 3.54	∗	2.73 ± 4.46	∗	0.90 ± 1.15	†		‡	†	‡
	−1.50 (−10.00-2.00)		2.00 (−6.00-11.00)		0.50 (0.00-3.00)
U1.PP (°)	−0.83 ± 3.95	NS	2.36 ± 3.14	∗	0.80 ± 1.85	NS		‡	‡	∗
	1.00 (-12.00-4.00)		3.00 (−3.50-8.00)		0.00 (−3.50-4.00)
L1i-VRmd (mm)	−3.93 ± 2.59	†	−2.96 ± 1.45	†	−0.13 ± 0.63	NS		∗	‡	‡
	−3.50 (−10.00- −1.00)		−3.00 (−6.00- −1.00)		0.00 (−1.50-1.50)
L1.HRmd (°)	−7.16 ± 3.12	†	−7.06 ± 3.86	†	−0.43 ± 1.51	NS		NS	‡	‡
	−7.00 (−13.00-0.00)		−7.50 (−13.00-2.00)		0.00 (−4.00-3.50)
L1.MP (°)	−7.83 ± 3.51	†	−5.40 ± 4.03	†	−0.83 ± 1.43	NS		‡	‡	‡
	−7.00 (−14.00- −2.00)		−4.50 (−16.50-2.00)		−0.50 (−3.50-1.00)
U6-VRmx (mm)	−0.03 ± 0.63	NS	1.93 ± 2.35	∗	−0.20 ± 0.64	NS		‡	‡	NS
	0.00 (−1.50-1.00)		2.50 (−4.00-5.00)		0.00 (−2.50-0.00)
U6-HRmx (mm)	0.16 ± 0.67	NS	0.60 ± 1.12	∗	0.00 ± 0.00	NS	NS
	0.00 (−1.00-1.50)		0.50 (−1.00-4.00)		0.00 (0.00-0.00)
Soft-tissue parameters
N′-Me′ (mm)	1.66 ± 3.79	NS	3.86 ± 2.59	†	0.46 ± 1.39	NS		‡	‡	‡
	2.00 (−6.00-8.00)		4.00 (0.00-10.00)		0.00 (−2.00-4.00)
Sn-Me′ (mm)	2.43 ± 2.08	†	3.86 ± 2.23	†	0.30 ± 1.46	NS		‡	‡	‡
	2.00 (−3.00-5.00)		4.00 (0.00-9.00)		0.00 (−2.00-3.00)
A′-VR (mm)	3.36 ± 1.20	†	2.66 ± 2.17	†	0.90 ± 0.91	†		‡	‡	‡
	3.50 (1.00-5.50)		2.00 (0.00-6.50)		1.00 (−1.00-2.50)
B′-VR (mm)	−2.86 ± 1.88	†	−2.90 ± 3.29	†	1.66 ± 1.35	†		NS	‡	‡
	−2.50 (−6.00-0.00)		−2.50 (−13.00-0.50)		2.00 (−0.50-4.00)
UL-VR (mm)	3.43 ± 1.76	†	2.63 ± 2.74	†	0.83 ± 1.09	∗		‡	‡	‡
	3.00 (1.00-7.00)		2.00 (−2.00-7.00)		1.00 (−1.00-3.00)
LL-VR (mm)	−1.33 ± 2.12	∗	−1.16 ± 2.41	NS	1.60 ± 1.05	†		NS	‡	‡
	−1.00 (−5.50-2.00)		−1.00 (−5.00-3.50)		2.00 (0.00-3.50)
Pg′-VR (mm)	−2.66 ± 2.34	†	−2.53 ± 2.23	†	1.76 ± 1.37	†		NS	‡	‡
	−2.00 (−6.00-0.50)		−3.00 (−6.50-1.00)		2.00 (−0.50-4.00)

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