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Year : 2012  |  Volume : 23  |  Issue : 2  |  Page : 289-291
Treatment of division II malocclusion in young adult with Forsus™ fatigue-resistant device

Department of Orthodontics and Dentofacial Orthopedics, A. B. Shetty Memorial Institute of Dental Sciences, Derlakatte, Mangalore, India

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Date of Submission02-Aug-2010
Date of Decision31-Aug-2010
Date of Acceptance13-Oct-2010
Date of Web Publication3-Sep-2012


The traditional technique for correcting class II malocclusion - involving the use of class II elastics and headgear - has been problematic due to its dependence on patient compliance. Functional orthopedic treatment seeks to correct malocclusions and harmonize the shape of the dental arch and orofacial functions. Removable functional appliances are normally very large in size, have unstable fixation, cause discomfort, exert pressure on the mucosa, reduce space for the tongue, cause difficulties in deglutition and speech, and very often affect esthetic appearance. With a fixed appliance like the Forsus™ fatigue-resistant device (FRD), as the appliance is fixed, there is less dependence on patient compliance and the remaining growth after the pubertal growth spurt can be harbored effectively. The Forsus™ FRD is not as rigid as the previous fixed functional appliances and hence is comfortable for the patients. In this case report we describe a patient at the end of the growth stage who had mandibular retrognathia and was successfully treated with the Forsus™ FRD.

Keywords: Class II correctors, fixed functional appliance, Forsus™ fatigue-resistant device

How to cite this article:
Krishna Nayak U S, Goyal V. Treatment of division II malocclusion in young adult with Forsus™ fatigue-resistant device. Indian J Dent Res 2012;23:289-91

How to cite this URL:
Krishna Nayak U S, Goyal V. Treatment of division II malocclusion in young adult with Forsus™ fatigue-resistant device. Indian J Dent Res [serial online] 2012 [cited 2023 Mar 22];23:289-91. Available from:

   Introduction Top

Treatment of class II malocclusion in adults generally involves orthognathic surgery or camouflage. Camouflage, if attempted, by removing the upper premolars in cases of mandibular retrognathia without any maxillary dentoalveolar excess, as for example this case, can lead to detrimental changes in the soft tissue profile of the patient. Treatment of the adult class II patients require careful diagnosis and treatment planning that takes into consideration esthetic, occlusal, and functional aspects.

The Forsus™ fatigue-resistant device (FRD) is an interarch push-spring that produces about 200 g of force when fully compressed. Since the Forsus™ FRD springs are rarely fully compressed, they are comparable in force level to heavy class II elastics. [1],[2] Also, the FRD can intrude the maxillary first molars and thus help in correcting a class II malocclusion without opening the bite. [3]

The distal end of the FRD's push-rod inserts into a telescoping cylinder, and a hook on the mesial end is crimped directly to the archwire near the canine or premolar brackets. The telescoping cylinder consists of inner and outer sliding tubes surrounded by an open-coil spring. An eyelet at the distal end of the cylinder is connected to the maxillary molar headgear tube with an L-pin. [4]

The push-rod has a built-in stop that compresses the spring when the patient's mouth closes. The spring then exerts equal and opposite forces onto the maxillary molars as well as the mandibular incisors. [5] This produces the tendency for distalization of the maxillary molars and flaring of the mandibular incisors.

   Case Report Top

A 19-year-old patient came with the chief complaint of backwardly placed central incisors [Figure 1] and [Figure 2]. The diagnosis was class II division II malocclusion associated with a retrognathic mandible and an overbite of 100%. Pretreatment cephalometric values confirmed a class II skeletal relationship with a ANB of 4°, FMA of 21°, and SN-GoGn of 23°.
Figure 1: Extraoral profile view showing the retrognathic mandible and the convex profile.

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Figure 2: Intraoral photograph showing severe class II division II malocclusion.

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Alignment was carried out using coaxial wire and NiTi wire to decompensate the incisor relationship. Wire size was progressively increased to 19 × 25 inches in both maxillary and mandibular arches [Figure 3]. The wires were cinched so that the forces from the FRD was transmitted to the entire arch as a unit to prevent the spaces from opening up. Pre Forsus™ cephalometric findings were ANB of 5°, FMA of 21°, and SN-GoGn of 26°. Upper incisor-to-NA was 36°, 6 mm; lower incisor-to-NB was 21°, 2 mm; and lower incisor-to-mandibular plane angle was 98°. At the end of alignment 9 mm of overjet was recorded.
Figure 3: Arches after the alignement phase, with 19 × 25 stainless steel wire placed.

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After 3 months of continuous wear of the Forsus™ FRD [Figure 4], the molar and canine relationship was class I, and midlines were coinciding. The soft tissue profile improved from before. The post Forsus™ cephalometric findings showed ANB of 2°, FMA of 22°, and SN-GoGn of 25°. Upper incisor-to-NA was 32°, 5 mm; lower incisor-to-NB was 34°, 7 mm; and lower incisor-to-mandibular plane angle was 119°.
Figure 4: Forsus™ fatigue-resistant device placed after the complete alignment of arches, with working stainless steel wires in place.

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The pre Forsus™ and post Forsus™ cephalometric findings [Table 1] show that the molar relationship had corrected and the lower incisors were flared. The chin-lip contour improved, with increased prominence of the chin and lip. The lower facial height remained constant.
Table 1: Case analysis

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Three months post Forsus™ removal [Figure 5] and [Figure 6] the changes seen cephalometrically and clinically remained constant. Long-term studies need to be done to evaluate the stability of these results.
Figure 5: Three months post appliance removal the overjet has reduced and occlusion is stable.

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Figure 6: Post-treatment extraoral profile photograph showing the considerable change in profile: the convex profile has now become straight.

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   Discussion Top

Treatment of class II malocclusion can be benefited by limiting the side effects, minimizing the need for patient compliance, and avoiding appliance breakage. Forsus™ FRD in our patient, who had completed growth, brought about primarily dentoalveolar changes. There was improvement in the soft tissue profile of the patient and the occlusion was perfected. At the end of treatment, good occlusion ensured the stability of the results.

   References Top

1.Ritto AK, Ferreira AP. Fixed functional appliances--a classification. Funct Orthod 2000;17:12-30, 32.  Back to cited text no. 1
2.Nelson B, Hansen K, Hägg U. Class II correction in patients treated with class II elastics and with fixed functional appliances: A comparative study. Am J Orthod Dentofac Orthop 2000;118:142-9.  Back to cited text no. 2
3.Heinig N, Göz G. Clinical application and effects of the Forsus spring. A study of a new Herbst hybrid. J Orofac Orthop 2001;62:436-50.  Back to cited text no. 3
4.Vogt W. The Forsus Fatigue Resistant Device. J Clin Orthod 2006;40:368-77.  Back to cited text no. 4
5.El-Sheikh MM, Godfrey K, Manosudprasit M, Viwattanatipa N. Force-deflection characteristics of the fatigue-resistant device spring: an in vitro study. World J Orthod 2007;8:30-6.  Back to cited text no. 5

Correspondence Address:
Varun Goyal
Department of Orthodontics and Dentofacial Orthopedics, A. B. Shetty Memorial Institute of Dental Sciences, Derlakatte, Mangalore
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0970-9290.100444

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  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]

  [Table 1]

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