Aim: To test the hypothesis that skeletal and dentoalveolar effects are both important in skeletal class II malocclusion corrected with the Forsus fatigue-resistant device (FRD). Materials and methods: A total of 35 patients (16 females and 19 males; age 12.0 ± 0.6 years) with skeletal class II malocclusion treated with the Forsus FRD were included. Lateral cephalometric radiographies before and after treatment were collected. Cephalometric analysis and superimpositions were applied. Pancherz's analysis was performed to discover the skeletal and dentoalveolar effects on all patients and 60% contribution was set as a milestone to classify. Statistical comparisons were performed by paired t testing (p < 0.05). Results: The mean treatment period of the Forsus FRD was 6.4 ± 0.2 months. All patients (AG) have been corrected to class I molar relationship in three mechanisms: 15 patients in the skeletal group (SG), 10 patients in the dentoalveolar group (DG), and 10 patients in the skeletal and dentoalveolar group (SDG). Four groups showed a significant change in skeletal sagittal relationship improvement (p < 0.05). The AG, SG, and SDG showed a significant improvement in the growth of the mandible (Co-Go, Go-Pog, and Co-Gn, p < 0.05). The DG showed a significant improvement in the growth of the mandibular body (Go-Pog, p < 0.05). Conclusion: Three mechanisms were found in skeletal class II malocclusion corrected with the Forsus FRD. Skeletal and dentoalveolar effects are both important in skeletal class II malocclusion corrected with the Forsus FRD. And skeletal and dentoalveolar effects played differential roles in different cases. Clinical significance: The mechanism of skeletal class II correction with Forsus FRD may divide into mandibular growth, dentoalveolar effects, and both.
Baccetti T, Franchi L, Stahl F. Comparison of 2 comprehensive class II treatment protocols including the bonded Herbst and headgear appliances: a double-blind study of consecutively treated patients at puberty. Am J Orthod Dentofacial Orthop 2009;135(6):698 e1– 698 e-10. DOI: 10.1016/j.ajodo.2008.03.015; discussion-9.
Wahl N. Orthodontics in 3 millennia. Chapter 9: functional appliances to midcentury. Am J Orthod Dentofacial Orthop 2006;129(6):829–833. DOI: 10.1016/j.ajodo.2006.03.019.
Heinig N, Göz G. Clinical application and effects of the forsus spring. a study of a new Herbst hybrid. J Orofac Orthop 2001;62(6):436–450. DOI: 10.1007/s00056-001-0053-6.
El-Sheikh MM, Godfrey K, Manosudprasit M, et al. Force-deflection characteristics of the fatigue-resistant device spring: an in vitro study. World J Orthod 2007;8(1):30–36.
Franchi L, Alvetro L, Giuntini V, et al. Effectiveness of comprehensive fixed appliance treatment used with the forsus fatigue resistant device in class II patients. Angle Orthodontist 2011;81(4):678. DOI: 10.2319/102710-629.1.
Barnett GA, Higgins DW, Major PW, et al. Immediate skeletal and dentoalveolar effects of the crown- or banded type Herbst appliance on class II division 1 malocclusion. Angle Orthod 2008;78(2):361–369. DOI: 10.2319/031107-123.1.
Aras A, Ada E, Saracoğlu H, et al. Comparison of treatments with the forsus fatigue resistant device in relation to skeletal maturity: a cephalometric and magnetic resonance imaging study. Am J Orthod Dentofacial Orthop 2011;140(5):616–625. DOI: 10.1016/j.ajodo.2010.12.018.
Bisztriczky T, Fejes Tóth G. An improved Version of the cervical vertebral maturation (CVM) method for the assessment of mandibular growth. Angle Orthod 2002;72(4):316–323. DOI: 10.1043/0003-3219(2002)072<0316:AIVOTC>2.0.CO;2.
Pancherz H. The mechanism of class II correction in Herbst appliance treatment. A cephalometric investigation. Am J Orthod 1982;82(2):104–113. DOI: 10.1016/0002-9416(82)90489-4.
Giuntini V, Vangelisti A, Masucci C, et al. Treatment effects produced by the twin-block appliance vs the forsus fatigue resistant device in growing class II patients. Angle Orthod 2015;85(5):784–789. DOI: 10.2319/090514-624.1.
Aras I, Pasaoglu A. Class II subdivision treatment with the forsus fatigue resistant device vs intermaxillary elastics. Angle Orthod 2017;87(3):371–376. DOI: 10.2319/070216-518.1.
Bock N, Pancherz H. Herbst treatment of class II division 1 malocclusions in retrognathic and prognathic facial types. Angle Orthod 2006;76(6):930–941. DOI: 10.2319/100605-352.
Oztoprak MO, Nalbantgil D, Uyanlar A, et al. A cephalometric comparative study of class II correction with Sabbagh universal spring (SUS(2)) and forsus FRD appliances. Eur J Dent 2012;6(3):302–310. DOI: 10.1055/s-0039-1698965.
Stucki N, Ingervall B. The use of the jasper jumper for the correction of class II malocclusion in the young permanent dentition. Eur J Orthod 1998;20(3):271. DOI: 10.1093/ejo/20.3.271.
Männchen R. A critical evaluation of the pitchfork analysis. Eur J Orthod 2001;23(1):1–14. DOI: 10.1093/ejo/23.1.1.
Ruf S, Wüsten B, Pancherz H. Temporomandibular joint effects of activator treatment: a prospective longitudinal magnetic resonance imaging and clinical study. Angle Orthodontist 2002;72(6):527–540. DOI: 10.1043/0003-3219(2002)072<0527:TJEOAT>2.0.CO;2.
Gomes AS, Lima EM. Mandibular growth during adolescence. Angle Orthodontist 2006;76(5):786–790. DOI: 10.1043/0003-3219(2006)076[0786:MGDA]2.0.CO;2.
Karacay S, Akin EH, Gurton AU, et al. Forsus nitinol flat spring and jasper jumper corrections of class II division 1 malocclusions. Angle Orthodontist 2006;76(4):666–672. DOI: 10.1043/0003-3219(2006)076[0666:FNFSAJ]2.0.CO;2.
Coatoam GW, Behrents RG, Bissada NF. The width of keratinized gingiva during orthodontic treatment: its significance and impact on periodontal status. J Periodontol 1981;52(6):307–313. DOI: 10.1902/jop.19188.8.131.527.
Artun J, Krogstad O. Periodontal status of mandibular incisors following excessive proclination. A study in adults with surgically treated mandibular prognathism. Am J Orthod Dentofacial Orthop 1987;91(3):225–232. DOI: 10.1016/0889-5406(87) 90450-1.
Nahas-Scocate AC, de Siqueira Brandao A, Patel MP, et al. Bone tissue amount related to upper incisors inclination. Angle Orthod 2014;84(2):279–285. DOI: 10.2319/031213-211.1.
Yodthong N, Charoemratrote C, Leethanakul C. Factors related to alveolar bone thickness during upper incisor retraction. Angle Orthod 2013;83(3):394–401. DOI: 10.2319/062912-534.1.
Aslan BI, Kucukkaraca E, Turkoz C, et al. Treatment effects of the forsus fatigue resistant device used with miniscrew anchorage. Angle Orthod 2014;84(1):76–87. DOI: 10.2319/032613-240.1.
Eissa O, El-Shennawy M, Gaballah S, et al. Treatment outcomes of class II malocclusion cases treated with miniscrew-anchored Forsus fatigue resistant device: a randomized controlled trial. Angle Orthodontist 2017;87(6):824–833. DOI: 10.2319/032717-214.1.