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ARAŞTIRMA (Research) Hacettepe Dişhekimliği Fakültesi Dergisi Cilt: 30, Sayı: 3, Sayfa: 74-84, 2006 Treatment Effects of Cervical Headgear and Lower Utility Arch Mechanics in Angle Class II Division 1 Low-Angle Patients Angle Sınıf II Bölüm 1 Malokluzyona Sahip Low-angle Hastalarda Servikal Headgear ve Alt Utility Ark Mekaniğinin Tedavi Üzerine Etkileri *Müge AKSU DDS, PhD, *Filiz YUKAY DDS, PhD *Hacettepe University, Faculty of Dentistry, Department of Orthodontics ABSTRACT ÖZET Objective: A prospective study was performed to evaluate the effects of cervical headgear and lower utility arch (CHG+LUA) in Class II division 1 lowangle patients and to determine whether reverse response occurred during the upper first molar distalization period. Subjects and Methods: Thirty patients were included in the study and were divided in two groups. The first group was treated with CHG+LUA while the second group was treated only with cervical headgear (CHG). After achieving Angle class I molar relation, the cephalograms were taken. Results: The assessment of cephalometric findings showed that significant reduction of maxillary protrusion, molar distalization, and extrusion were obtained in both groups. LUA influenced the lower molar uprighting and the lower incisor intrusion significantly. The rotation of the mandible showed a significant increase in CHG group while it remained constant in CHG+LUA group. Conclusion: These results showed that reverse response effect, which may be an effective way of controlling the mandibular rotational response, could be achieved by CHG+LUA. Amaç: Sınıf II bölüm 1 malokluzyona sahip lowangle hastalarda servikal headgear ve alt utility ark (CHG+LUA) uygulamasının etkilerini incelemek ve üst birinci molar distalizasyonu sırasında mandibulada “ters yanıt” etkisinin olup olmadığını araştırmaktır. Bireyler ve Yöntem: Tedaviye dahil edilen toplam 30 birey iki gruba ayrılmış, birinci gruba CHG+LUA, diğer gruba sadece CHG uygulanmıştır. Angle sınıf I molar ilişkisi elde edildikten sonra lateral sefalogramlar alınmıştır. Bulgular: Sefalometrik değerlendirmelerden elde edilen bulgular, her iki grupta da maksiller protrüzyonda azalma, molar distalizasyonu ve ekstrüzyonu elde edildiğini göstermektedir. Alt utility ark, alt molarda anlamlı dikleşmeye ve alt kesicilede anlamlı intrüyona neden olmuştur. Mandibuler rotasyon CHG grubunda anlamlı şekilde artarken, CHG+LUA grubunda sabit kalmıştır. Sonuç: Araştırma sonuçları, mandibular rotasyonun kontrolünde etkin bir yol olan “ters yanıt” etkisinin CHG+LUA uygulaması ile elde edilebileceğini göstermiştir. KEYWORDS Cervical headgear, lower utility arch, Class II division 1 ANAHTAR KELİMELER Servikal headgear, alt utility ark, Sınıf II bölüm 1 118 Introduction Extraoral traction is the most reliable method for management of maxillary protrusion and still continues to be a major treatment alternative for the orthodontists. The decision as to which type of headgear to use in the treatment of growing patients with skeletal and dental class II malocclusion has been discussed by many investigators1-6. Cervical headgear has been most frequently used in cases of skeletal maxillary protrusion, producing distal displacement of the maxilla, increasing the vertical dimension and generating mandibular clockwise rotation7,8. Because some studies have shown the upper molar extrusion and the opening rotation of the mandible besides the distalization effect of cervical headgear5,910, many orthodontists tend to avoid using cervical headgear when a patient with class II maxillary protrusion has a vertical growth pattern. Some investigators have stated that mandibular plane angle opens with the cervical headgear11,12, while others have disagreed with this statement, believing that mandibular plane closes or does not change with treatment1,13. Many authors have reported significant changes in vertical parameters when patients treated with cervical headgear compared to patients treated without the use of headgear14-16, or patients treated with occipital or high-pull headgear4,12,16,17. However, Ricketts et al18 suggested that the effect of cervical headgear did not occur as it has been accepted in the literature. According to the authors18, when a cervical headgear is used in high-angle patients, the extrusion of both maxillary molar and maxilla causes a reciprocal clockwise rotation of the mandible, resulting in a higher face height. On the contrary, in low-angle patients, the authors stated that the extrusive forces of cervical headgear cause changes in the dentition rather than in the facial proportions. In those cases, where a cervical headgear is used in combination with a lower utility arch, the mandible may rotate in a counterclockwise direction. This effect is called “reverse response” of the mandible and the mandibular arch. This is almost entirely a functional response and adverse to the common concepts. The purpose of this prospective study was (1) to evaluate the skeletal and dental effects of cervical headgear and lower utility arch (CHG+LUA) in Class II division 1 low-angle patients whether reverse response occurs (2) and to compare the dental and skeletal differences between CHG+LUA and CHG during the upper first molar distalization. Subjects and Method The sample consisted of thirty patients (14 boys and 16 girls) either in the late mixed or permanent dentition ranging in age from 9.08 to 13 years. The inclusion criteria for the patients in the study were as follows: (1) Class II division 1 skeletal maxillary protrusion with a low-angle growth pattern (SNA>80o, ANB>4o, maxillary depth angle>90o, lower facial height< 47o, FMA<25o, GoGnSN < 32o) (2) Half to one full cusp upper molar deviation (3) None or minimal crowding (4) Good cooperation The subjects were divided into two groups randomly. The first group consisted of 15 patients (8 boys and 7 girls) with a mean age of 10.54 ± 1.05 years, whose treatment included an orthopedic cervical headgear in conjunction with a lower utility arch18,19. The second group consisted of 15 patients (6 boys and 9 girls) with a mean age of 10.52 ± 0.96 years, whose treatment included an orthopedic cervical headgear only. These patients did not wear any other appliances during the distalization. The first group was closely matched for age and dentoskeletal characteristics with the patients in the second group (Table I). The headgear used for both groups was Kloehn type (GAC International, Bohemia, NY) with a long outer bow. All the patients were instructed to wear the CHG 14-16 hours per day with an orthopedic force of 500 gm18. The lateral cephalograms were taken at the start of treatment (T1) and after molar distaliza- 119 tion was completed (T2). The radiographs were traced by one investigator (M.A.) to verify anatomic landmarks (Figure 1A). The duration of distalization was 1.23 ± 0.42 years in the CHG+LUA group and 1.17 ± 0.30 years in the CHG group. The skeletal and dentoalveolar effects of CHG + LUA and CHG were then compared by cephalometric analysis. Maxillary and mandibular skeletal responses were documented by comparing the means of cephalometric measurements at T1 and T2 (Figure 1B). The dental measurements (Figures 1C and 1D) were obtained through maxillary and mandibular superimpositions, respectively18-20. Maxilla was superimposed on the palatal plane at ANS and mandible was superimposed on the corpus axis at Pm. The long axis of maxillary and FIGURE 1b 1 SNA (°) 6 GoGnSN (°) 2 SNB (°) 7 FMA (°) 3 Palatal plane-FH (°) 8 Lower facial height (°) 4 Maxillary depth (°) 9 Cant of occlusal plane (°) 5 Facial depth (°) FIGURE 1a 1 Nasion 14 L6 mesial apex 2 3 Sella Orbitale 15 L6 bifurcation 16 B point 4 Porion 17 Pm 5 A point 18 Pogonion 6 U1 crown 19 Menton 7 U1 apex 20 Gonion 8 U6 mesiobuccal cusp tip 21 Xi point 9 U6 mesiobuccal apex tip 22 R1 10 U6 trifurcation 23 R3 11 L1 crown 24 ANS 12 L1 apex 25 PNS 13 L6 mesiobuccal cusp FIGURE 1c 1 Palatal plane 2 Line perpendicular to palatal plane from ANS 3 U6, distalization of the crown (mm) 4 U6,distalization of the trifurcation (mm) 5 U6, angulation (°) 6 U6, vertical displacement (mm) 7 U1, horizontal displacement of the crown (mm) 8 U1, horizontal displacement of the apex (mm) 9 U1, angulation (°) 10 U1, vertical displacement (mm) 120 axis respectively. The vertical movements of the maxillary and mandibular first molars and incisors were determined by measuring the perpendicular distances between the mesiobuccal cusp tip of the maxillary molar, mesial cusp tip of the mandibular first molar and incisal edges of the maxillary and mandibular incisor teeth relative to the palatal plane and corpus axis at T1 and T2. Statistical analysis FIGURE 1d 1 Corpus axis 2 Line perpendicular to corpus axis from Pm 3 L6, distalization of the crown (mm) 4 L6, distalization of the bifurcation (mm) 5 L6, angulation (°) 6 L6, vertical displacement (mm) 7 L1, horizontal displacement of the crown(mm) 8 L1, horizontal displacement of the apex (mm) 9 L1, angulation (°) The means and standard deviations were calculated for each cephalometric variable. Paired t-test was performed in each group to analyze the changes from T1 to T2. Student t-test was used to evaluate intergroup differences at different periods (T1-T2). To determine the accuracy of the method, 15 cephalograms were retraced and recalculated by the same investigator. The reliability coefficients were between 0.93 and 0.99 for linear measures, and between 0.91 and 0.97 for angular measures, indicating a high level of consistency. 10 L1, vertical displacement (mm) Results mandibular first molar teeth were constructed by drawing a line through the apexes and the mesiobuccal and mesial cusp tips for the upper and lower first molars. The long axes of incisor teeth were constructed through the incisal edge and apex. The angular differences in teeth positions were measured as the angles between the long axis of each maxillary and mandibular tooth and the lines perpendicular to palatal plane and corpus axis at T1 and T2. To determine the amount of molar distalization, the distances between the cusp tip of the maxillary first molar and the line perpendicular to palatal plane from ANS and the cusp tip of the mandibular first molar and the line perpendicular to corpus axis from Pm were used. The distances of the trifurcation and the bifurcation were also measured to determine the amount of tipping after distalization. The amount of horizontal displacements of maxillary and mandibular incisors was measured on a line parallel to the palatal plane and corpus Maxillary depth angle decreased significantly in CHG+LUA and CHG groups with a mean change of 1.87o and 1.93o respectively (p<0.05, Table II). The mean changes in SNA angle did not indicate a significant reduction in both groups (p>0.05, Table II) while palatal plane angle decreased significantly in CHG group (p<0.05, Table II). The upper first molar (U6) in CHG + LUA and CHG groups moved distally with respect to its crown (4 mm, and 1.77 mm respectively, p< 0.05, Table III). However, the distalization of the trifurcation of the upper first molar showed significant difference in CHG + LUA group (2.4 mm, p< 0.05, Table III), while there was no significant difference in the CHG group (0.77 mm, p> 0.05, Table III) during cervical headgear therapy. The change in the angulation of the U6 was statistically different in the CHG+LUA group, indicating that the tooth was distalized by tipping of the crown rather than the bodily movement. 121 TABLE I Pretreatment variables Variables CHG+LUA (n=15) CHG (n=15) Mean SD Mean SD P SNA (º) T1 81.90 ± 3.34 81.33 ± 3.02 NS ANB (º) T1 5.67 ± 1.33 5.76 ± 1.67 NS Maxillary depth (º) T1 91.60 ± 1.53 91.13 ± 1.89 NS Lower facial height (º) T1 42.73 ± 3.58 42.97 ± 2.66 NS FMA (º) T1 22.87 ± 1.9 23.73 ± 1.76 NS GoGnSN (º) T1 32.30 ± 1.11 32.63 ± 2.66 NS Age T1 10.54 ± 1.05 10.52 ± 0.96 NS * p<0.05 SD: standard deviation NS: not significant TABLE II T1 (pretreatment) and T2 (after the distalization period) values of maxillary skeletal measurements Variables Maxillary depth (º) T1 CHG+LUA (n=15) CHG (n=15) Mean SD P 91.60 ± 2.53 Mean SD 81.90 ± 3.34 0.008* SNA (º) 0.000* T2 89.73 ± 2.56 89.20 ± 1.69 T1 81.90 ± 3.34 81.33 ± 3.02 NS Palatal plane-FH (º) NS T2 80.80 ±3.78 80.50 ±2.63 T1 1.97 ±3.07 3.07 ±3.58 0.002* NS T2 0.93 ±3.22 P 0.87 ±3.59 * p<0.05 SD: standard deviation NS: not significant (5.6º, p< 0.05, Table III). On the other hand, the angulation of the U6 in CHG group did not change significantly (-0.17º, p> 0.05, Table III). In both groups, the upper first molar showed significant vertical change (1.07 mm, and 1. 43 mm respectively, p< 0.05, Table III). The only significant change of the upper incisor (U1) in the CHG +LUA group was found in the horizontal displacement of the upper incisor’s apex (0.93 mm lingually, p< 0.05, Table III). The horizontal, the angular and the vertical changes in the position of the U1 did not differ in the CHG group (p>0.05, Table III). 122 TABLE III T1 (pretreatment) and T2 (after the distalization period) values of maxillary dental measurements Variables U6, distalization T1 CHG+LUA (n=15) CHG (n=15) Mean SD P -36.17 ± 3.41 of the crown (mm) U6, distalization 0.015* T2 -40.17 ± 3.72 -40.63 ± 3.68 T1 -37.13 ± 2.69 -38.40 ± 2.48 0* NS T2 -39.53 ± 2.76 -39.17 ± 2.91 T1 15.27 ± 6.52 19.70 ± 2.91 0.014* U6, vertical U1, horizontal NS T2 20.87 ± 7.42 19.87 ± 9.36 T1 20.90 ± 2.93 20.37 ± 1.58 displacement (mm) 0.046* 0.001* T2 21.97± 2.71 21.80 ± 1.68 T1 -1.17 ± 3.26 -1.63 ± 3.11 displacement of NS NS the crown (mm) T2 -1.70 ± 3.50 -0.83 ± 2.76 U1, horizontal T1 -10.33 ± 2.09 -11.60 ± 1.76 displacement of 0.019* NS the apex (mm) T2 -11.27 ± 1.94 -10.93 ± 2.80 U1, angulation (º) T1 21.40 ± 6.43 23.10± 7.08 NS U1, vertical NS T2 21.90 ± 7009 25.00 ± 6.71 T1 29.37 ± 2.62 28.47 ± 1.89 displacement (mm) NS T2 30.03 ± 2.27 P -38.87 ± 2.86 0* of the trifurcation (mm) U6, angulation (º) Mean SD NS 28.53 ± 2.46 * p<0.05 SD: standard deviation NS: not significant The mandibular skeletal measurements showed no statistically significant changes in both groups (SNB, facial depth angle) (p>0.05, Table IV). The measurements such as GoGnSN, FMA, lower facial height did not show any signifi- cant difference in the CHG+LUA group (p>0.05, Table IV) while there was a significant increase in FMA, and lower facial height in the CHG group (p<0.05, Table IV). 123 TABLE IV T1 (pretreatment) and T2 (after the distalization period) values of mandibular skeletal measurements and facial pattern Variables SNB (º) T1 CHG+LUA (n=15) CHG (n=15) Mean SD P 76.23 ± 2.92 Mean SD 75.57 ± 2.33 NS Facial depth (º) NS T2 76.67 ± 3.68 76.07 ± 2.80 T1 86.93 ± 2.28 86.37 ± 2.23 NS GoGnSN (º) NS T2 86.73 ± 2.22 85.90 ± 2.19 T1 32.30 ± 1.11 33.63 ± 2.66 NS FMA (º) NS T2 33.27 ± 4.71 33.63 ± 6.17 T1 22.87 ± 1.9 23.73 ± 1.76 0.016* NS Lower facial height (º) T2 23.30 ± 3.60 24.90 ± 4.60 T1 42.73 ± 3.58 42.97 ± 2.66 0.047* NS T2 43.40 ± 3.89 P 43.83 ± 3.51 * p<0.05 SD: standard deviation NS: not significant The crown of the lower first molar (L6) in the CHG+LUA group was distalized and tipped back significantly (with a mean difference of 2.5 mm and 8.3˚, p< 0.05, Table V).The vertical change in the position of the L6 was not shown to be significantly different in CHG+LUA group. The crown of the lower incisor (L1) in the CHG+LUA group retroclined and intruded significantly with a mean difference of 4.73˚ and 1.13 mm respectively (p<0.05, Table V).The cant of occlusal plane increased 2.47˚ (p<0.05, Table V) in the CHG+LUA group while there was no significant change in the CHG group. In CHG group, all the variables determinig the L6 and L1 positional changes, did not also show any significant difference during distalization (p>0.05, Table V). Within all the skeletal measurements regarding the maxilla and the mandible, neither of the variables showed any significant difference between the two groups. The distalization of the U6 was significantly different between the two groups (p<0.05, Table VI). In CHG+LUA group, both the crown and the trifurcation moved distally with a mean difference of 4 mm and 2.4 mm respectively. On the other hand, in the CHG group, the distalization of the crown and the trifurcation was 1.77 mm and 0.97 mm respectively. The horizontal displacement of the U1 was significantly different between the two groups (p<0.05, Table VI). In the CHG+LUA group, U1 moved 0.53 mm lingually while in the CHG group, U1 moved 0.8 mm labially. For the L6, the distalization of the crown (2.5 mm for the CHG+LUA group and 0 mm for the CHG group) and the bifurcation (2.4 mm for the CHG+LUA group and 0.97 mm for the CHG group) and the 124 TABLE V T1 (pretreatment) and T2 (after the distalization period) values of mandibular dental measurements Variables L6, distalization T1 CHG+LUA (n=15) CHG (n=15) Mean SD P -32.80 ± 2.41 of the crown (mm) L6, distalization NS T2 -35.30 ± 2.70 -33.77 ± 2.40 T1 -33.80 ± 0.74 -34.37 ± 0.16 NS NS T2 -34.56 ± 2.70 -34.46 ± 0.16 T1 -10.33 ± 10.49 11.20 ± 7.0 0* L6, vertical L1, horizontal NS T2 18.77 ± 6.15 11.0 ± 4.45 T1 13.23 ± 1.49 12.87 ± 1.43 displacement (mm) NS NS T2 13.60 ± 1.65 12.77 ± 2.41 T1 -6.13 ± 1.87 -5.70 ± 1.87 displacement of 0.011* NS the crown (mm) T2 -7.53 ± 2.83 -6.27 ± 1.72 L1, horizontal T1 -8.70 ± 1.87 -7.67 ± 1.03 displacement of NS NS the apex (mm) T2 -8.30 ± 2.83 -7.63 ± 1.16 L1, angulation (º) T1 6.47 ± 5.72 4.80 ± 4.56 0.012* L1, vertical Cant of occlusal NS T2 1.73 ± 8.91 25.40 ± 1.80 T1 25.50 ± 2.0 26.50 ± 2.24 displacement (mm) 0.017* T2 24.37 ± 2.57 T1 18.13 ± 0.98 plane (º) NS 19.10 ± 3.84 0.019* T2 *p<0.05 SD: standard deviation NS: not significant 20.60 ± 0.86 P -33.77 ± 2.35 0.006* of the bifurcation (mm) L6, angulation (º) Mean SD NS 20.73 ± 2.63 125 TABLE VI Comparison of pre and post-distalization differences between groups CHG+LUA (n=15) CHG (n=15) Mean SD Mean SD P U6, distalization of the crown (mm) -4.0 ± 2.65 -1.77 ± 2.46 0,02* U6, distalization of the trifurcation (mm) -2.4 ± 1.48 -0.97 ± 1.93 0,03* U1, horizontal displacement of the crown (mm) -0.53 ± 1.42 0.8 ± 1.80 0,03* L6, distalization of the crown (mm) -2.5 ± 3.01 0 ± 1.57 0,008* L6, distalization of the bifurcation (mm) -2.4 ± 1.48 0.97 ± 1.93 0,03* L6, angulation (º) 8.43 ± 5.47 -0.20 ± 7.52 0,001* L1, vertical displacement (mm) -1.13 ± 1.62 1.10 ± 2.75 0,01* Variables *p<0.05 SD: standard deviation NS: not significant angulation (8.43o for the CHG+LUA group and -0.20o for the CHG group) were significantly different between the study groups (p<0.05, Table VI). The vertical displacement of L1 was also significantly different between the two groups (p<0.05, Table VI). (L1 intruded with a mean difference of 1.13 mm in the CHG+LUA group while extruded with a mean difference of 1.10 mm in the CHG group). Discussion A prospective investigation was undertaken to determine the effects of CHG+LUA in Class II division 1 low-angle patients. The orthopedic effect of CHG has previously been the subject of many studies1-3,5-7,14. In contrast with the common concepts about the mandibular rotational effects, Ricketts et al18 suggested that a reverse response could occur when a CHG was used with a LUA in low-angle patients. According to the authors,18 the extruding upper molar picks up the lower molar, uprighting that tooth in a distal rotation. This action allows the maxilla to be compressed and rotated distally without rotation of the mandible and is referred to as the reverse response of the LUA18. However, CHG therapy accompanying by LUA has been rarely investigated20. The only investigation reported in the literature was the retrospective study of Cook et al20, which was performed in high-angle patients. The purpose of this study was not to focus on posttreatment effects but to evaluate pure effects of CHG+LUA during the molar distalization period as the overall change for the entire period of treatment may hide the CHG effect. In this study, the maxilla moved distally in terms of maxillary depth angle. Our finding is in accordance with the finding of many studies indicating the restriction of the maxilla with the use of CHG4,9,21,22. However, SNA angle did not show any significant difference during the distalization while some authors interpreted differences in SNA reduction7,21,23. The observation period in this study included only the distalization period, which might be insufficient to achieve an orthopedic movement. The literature regarding the effect of CHG on the palatal plane angle is still unclear. Although many authors reported that anterior nasal spine to be positioned downward more than posterior nasal spine1,3,5,11,18,24, rotation of the palatal plane was changed significantly only in CHG group. Boecler13 et al reported no change in the angulation of the palatal plane with CHG therapy in contrast to our finding. 126 The results of this study indicate that there was a significant distalization of U6 in both groups. This finding is in accordance with the findings reported in the literature1,9. However, the amount of distalization in CHG group was less than that of CHG + LUA group. Although the duration of distalization was almost the same, a difference between the amounts of distalization occurred. This might be due to the variation in the amount of molar cusp deviation at the start of treatment. Another possible explanation for this might be the angular changes between the two groups during the distalization period. To investigate the type of molar movement, distalization of the trifurcation of U6 was also evaluated. The amount of distalization of the trifurcation was less than the crown movement in contrast with the studies reported in the literature20,25. Furthermore, Schiavon Gandini et al25 showed that the distal relocation of U6 was more significant in the apex due to the 20o upward angulation of the external bow. Additionally, Cook et al20 did not observe any distal tipping when the outer bows of the CHG were bent upward. The downward vector of the extraoral force produced a more downward movement of U6 in both groups. Cook et al20 reported the upper molar extrusion either with or without treatment, suggesting that the molar extrusion could not be attributed to only cervical headgear due to the ongoing downward growth of the maxilla. In this study, the lower first molar moved distally and the lower incisors intruded and retroclined significantly in the CHG+LUA group as described by Ricketts et al.18 The bioprogressive theory of cortical anchorage hypothesizes that bends in the utility arch will move the roots of the first lower molars toward the buccal cortical bone of the mandible, leading to the extrusion of the lower first molars and the intrusion of lower incisors. The upper molar in the CHG+LUA group extruded, then uprighted the lower first molar in a distal rotation, confirmig the reverse response effect of the LUA. In contrast with our findings, Cook et al did not find any reverse response effect in their study group. Additionally, L1 and the cant of the occlusal plane were also changed by the LUA. The LUA might have a reaction at the molar to upright it however, cortical anchorage might prevent the significant molar extrusion even when the incisor intrusion mechanics were used. Meanwhile, Cook et al20 did not find any molar response while they found a significant intrusion and proclination of the lower incisors. Since no other appliances were worn by the patients in our study during the period of the investigation, it can be stated that CHG+LUA used in this study produced Class II correction without producing an opening rotation of the mandible. GoGnSN, FMA and lower facial height angles did not demonstrate any significant changes between T1 and T2 in CHG+LUA group, confirming that when a CHG is used in conjunction with a LUA, the mandible may remain constant without any rotation. Ricketts et al18 also suggested that the extrusive forces of CHG was translated through the utility arch to the lower dentition, allowing maxilla to move distally without rotation of the mandible. Cook et al20 reported different results with our findings regarding mandibular rotation, this might be due to their study group which was different from that of our study. A limitation of this study was that the groups were relatively small. However, the characteristics of the patients and the application of the appliances were highly homogeneous and the study was designed prospectively. Most of the studies pertaining to CHG are either retrospective or CHG has been combined with edgewise appliances; functional appliances, bite plates, extractions and the groups in these studies are not usually homogeneous. Additionally, there is only one study in the literature, investigating the speculation of Ricketts et al.18 Future studies including larger study groups and posttreatment effects should be undertaken for the long-term effects of CHG+LUA. Conclusion Both CHG+LUA and CHG groups restricted maxillary sagittal growth and resulted in an 127 extrusion of upper first molars. The lower first molar uprighted and moved distally with LUA, however, it could not prevent the extrusion but might restrict the excessive extrusion of the upper first molar. 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A cephalometric evaluation of nonextraction cervical headgear treatment in Class II malocclusions. Angle Orthod. 1994; 64:359-370. 25. Schiavon Gandini MREA, Gandini Jr LG, Da Rosa Martins JC, Del Santo Jr M. Effects of cervical headgear and edgewise appliances on growing patients Am J Orthod Dentofacial Orthop. 2001; 119:531-539. 26. Phan XL, Schneider BJ, Sadowsky C, BeGole AE. Effects of orthodontic treatment on mandibular rotation and displacement in Angle Class II Division 1 malocclusions. Angle Orthod. 2004; 74:174–183. CORRESPONDING ADDRESS Müge AKSU DDS, PhD Hacettepe University, Faculty of Dentistry, Department of Orthodontics 06100 Sıhhiye-Ankara/TURKEY Tel: +90 312 3116461 Fax: +90 312 3091138 e-mail: [email protected]