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Year : 2022  |  Volume : 40  |  Issue : 1  |  Page : 81-85

Cephalometric evaluation of the cervical spine posture following fixed functional therapy with Forsus™ appliance

1 Department of Orthodontics, Mithila Minority Dental College and Hospital, Darbhanga, Bihar, India
2 Faculty of Dentistry, SEGi University, Selangor, Malaysia
3 Department of Orthodontics, Awadh Dental College, Jamshedpur, Jharkhand, India

Date of Submission16-May-2021
Date of Decision21-Feb-2022
Date of Acceptance05-Mar-2022
Date of Web Publication13-Apr-2022

Correspondence Address:
Dr. Priyadarshini Hesarghatta Ramamurthy
Faculty of Dentistry, SEGi University, No. 9 Jalan Teknologi, PJU 5, Kota Damansara, Selangor 47810
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/jisppd.jisppd_173_21

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Background: To investigate whether fixed functional therapy for mandibular advancement with the Forsus™ appliance would produce any changes in the cervical spine posture. Materials and Methods: This prospective clinical exploratory study was conducted on 12 patients (six females and six males) with a mean age of 15 ± 1.3 years, having mandibular retrusion, Class II malocclusion, who were treated with the Forsus™ appliance. Lateral cephalogram was taken twice, once at the baseline (T1) before the commencement of the treatment and once following termination of fixed functional treatment (T2). Eleven measurements representing the vertical and the sagittal craniofacial proportions, and the head posture, were taken into account. Data were analyzed using SPSS version 22. The variations between before and after treatment measurements were collated using paired t-test. P < 0.05 was considered statistically significant. Results: No significant differences were noticed in the angle linking the horizontal lines of the head and the superior crest of the spinal column before and after the treatment, with P = 0.73. The cervical curvature angle also failed to show any significant difference with P = 0.14. Conclusion: Fixed functional therapy with the Forsus™ device resulted in dentoalveolar and soft tissue alterations alone but did not alter the cervical spine posture.

Keywords: Cervical vertebrae, fixed, mandibular advancement, orthodontic appliances, posture

How to cite this article:
Malik N, Fernandes BA, Ramamurthy PH, Anjum S, Prakash A, Sinha A. Cephalometric evaluation of the cervical spine posture following fixed functional therapy with Forsus™ appliance. J Indian Soc Pedod Prev Dent 2022;40:81-5

How to cite this URL:
Malik N, Fernandes BA, Ramamurthy PH, Anjum S, Prakash A, Sinha A. Cephalometric evaluation of the cervical spine posture following fixed functional therapy with Forsus™ appliance. J Indian Soc Pedod Prev Dent [serial online] 2022 [cited 2023 Feb 4];40:81-5. Available from: http://www.jisppd.com/text.asp?2022/40/1/81/343007

   Introduction Top

The pediatric dentist is in a unique position to positively influence the development of the face and occlusion of a child, through early diagnosis and appropriate referral for orthodontic consultation. Clinically, the child's face and related skeletal structures can be altered, when the child is still in the growing phase. However, forces exerted to correct occlusion, might have an impact on the body posture, especially in growing children. Studies in the past have shown corroboration for the interrelationship between malocclusion and body posture, particularly in relation to the head and neck.[1],[2],[3] This could be attributed to the fact that the stomatognathic system is anatomically interlinked to the cervical vertebrae and any changes in the mouth, jaws and closely related structures can affect the body posture.[4],[5] A possible interaction between the growth of the craniofacial complex and spinal development has also been postulated. The “soft tissue stretching hypothesis” by Solow and Sandham,[5] highlights the important influence of the cervical posture functionally on maxillomandibular growth. A study has also shown that tangible benefits in the postural balance could be accomplished with the myocentric position of the maxilla and mandible.[6] Hence, it is rational to postulate that forces exerted during correction of skeletal malocclusion can influence the cervical spine posture impactfully.

Among the various forms of malocclusion, Class II malocclusion has been considered the most challenging type when it comes to its correction.[7] Class II malocclusion can be a sequel of several skeletal and dentoalveolar factors.[8] However, the ideal treatment for Class II malocclusion in which the mandible is retrognathic, is to modify the amount or direction of growth of the mandible by using functional appliances.[9]

Functional appliances can be of removable or fixed type. A variety of fixed appliances are available for treating Class II malocclusion, and one such appliance which is used most often, especially in growing young patients, is the Forsus™ appliance. It is a type of functional orthopedic appliance which has the potential to stimulate mandibular growth. The greatest advantage of this appliance is that there is no need for patient compliance and the treatment outcome will be under the control of orthodontist.[10] However, functional appliances can modify muscular activity that has a bearing on the function and position of the mandible, which in turn can create pressure. The forces generated by it are relayed to the basal skeletal tissues and bring about changes which are orthodontic and orthopedic in nature.[11] Some studies have been done previously to evaluate whether the Twin block appliance, a removable functional appliance, used for alteration of Class II malocclusion had any effect on the cervical spine posture.[12],[13] However, when it comes to the fixed functional appliance, there are no studies available to assess its effects on cervical spine posture. Hence, the present study was undertaken to investigate whether fixed functional therapy for mandibular advancement in Class II malocclusion with the Forsus™ appliance produces any changes in the cervical spine posture in children.

   Materials and Methods Top

This prospective exploratory clinical study was undertaken on 12 patients (six boys and six girls) having mandibular retrusion, with Class II malocclusion. Ethical clearance was obtained from the institutional ethics committee (MMDCH/EC/2017/E19). Written informed consent was acquired from all the parents of the participating children, after explaining the treatment and study objectives. The sample size was determined as 12 based on a previous study.[14] To be included in this study, the participants had to be in the age range of 13–18 years having skeletal Class II malocclusion (ANB <5°), that required treatment with Forsus™ appliance. Furthermore, the participants had to be systemically healthy. Patients whose parents did not consent for the study, patients with existing caries, missing teeth, temporomandibular joint abnormalities, and patients who had undergone any surgeries previously, were excluded from the study.

Cephalometric analysis

All examinations were carried out by a single calibrated examiner. The calibration was done on repeated measurements of 5 cephalograms from participants not related to this study. Intraobserver reliability was measured using intraclass correlation coefficient which was 0.82. At the first visit, a lateral cephalogram (T1) was taken using rigid head fixation and 165 cm distance from the film to the tube, utilizing an Orthoralix R9 200 (Gendex, Kavo, Milan, Italy). All cephalograms were manually traced with a 0.5 mm lead pencil on acetate sheets kept over an illuminator. Angular readings were calculated utilizing a protractor. Measurements representing the vertical and the sagittal craniofacial dimensions and the head posture were estimated. These measurements included:

  • SNA– angle representing the anterior-posterior position of the maxilla in relation to the cranial base
  • SNB– angle representing the anterior-posterior position of the mandible in relation to the cranial base
  • ANB– angle indicating the magnitude of the sagittal skeletal jaw discrepancy
  • AFH (N-Me)– anterior face height
  • LFH (ANS-Me)– lower face height
  • SN to MP (Go-Gn)– angle representing the inclination degree of the mandibular plane in relation to the anterior base of the cranium.
  • SN to PP (ANS-PNS)– angle indicating the inclination degree of the maxillary plane in relation to the anterior base of the cranium
  • OP-SN (Occlusal plane to SN)– angle determining the rotation of the occlusal plane in relation to the anterior base of the cranium.

A list of all cephalometric measurements has been provided in [Table 1] and demonstrated in [Figure 1].
Table 1: Reference lines on the cephalograms

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Figure 1: Reference lines on cephalogram

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Treatment protocol

All 12 patients were treated with the fixed appliance. MBT brackets with 0.022” slots were placed. The Forsus™ appliance was placed after completion of leveling and aligning phase. A 19 × 25 stainless steel wire was positioned in both arches. The Forsus™ rods were fitted on the mandibular arch, distally to the canine. The mandibular arch was banded distally to the hindmost molars and lateral group components were attached together, from the molar to the canine, to avert any establishment of spaces. The treatment continued to the predetermined results was obtained.

At the completion of the treatment after 20–24 months, patients were recalled for posttreatment cephalogram (T2). The same operator took the cephalogram, and all the measurements were recorded using the same criteria used at baseline examination [Figure 2] and [Figure 3].
Figure 2: Pretreatment cephalogram

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Figure 3: Posttreatment cephalogram

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Data were analyzed using SPSS version 22 (IBM Corporation, Armonk, NY, USA). Pre-and Postcephalometric assessments were compared utilizing paired t-test. P < 0.05 was considered statistically significant.

   Results Top

All the 12 patients enrolled for the study completed the treatment and were available for obtaining final measurements. Hence, the study did not have any attrition. The mean cephalometric measurement differences between T1 and T2 are presented in [Table 2]. A significant change occurred between pre-and post SNA° (P < 0.001), SNB° (P < 0.001) angles, and ANB° angle (P < 0.001). A growth rise was observed in the vertical dimension. The variation between T1-T2 was significant in SN/MP (P = 0.002) and SN/odontoid process tangent (OPT) (P < 0.001), respectively.
Table 2: Evaluation of cephalometric parameters between pre (T1)-and posttreatment (T2) findings

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A significant change was observed in MP/OPT angle (P < 0.001), SN/cerebral vertebrae tangent (CVT) angle (P < 0.001) between the midsection of the spinal column (CVT) and horizontal lines of the head (SN), which showed an increase after the treatment (P < 0.001).

No significant variations were observed before and after treatment, in the angle intervening the palatal plane (anterior nasal spine-posterior nasal spine [PP]) and the upper section of the spinal column (OPT), in the present study (P = 0.73).

Angle between PP/CVT (palatal plane and cervical vertebrae tangent) did not show a significant difference in T1 and T2. No significant increase in cervical curvature angle (OPT/CVT) was found after the treatment (P = 0.14).

   Discussion Top

Class II malocclusion can affect the function and facial esthetics of patients and pose a great challenge to the orthodontist during its correction.[15] There are numerous management strategies for Class II malocclusion. The Forsus™ appliance is a unique stereotypical noncompliance fixed functional appliance used nowadays in the alteration of Class II malocclusion. Although it has a reasonable active treatment time, the skeletal and dental effects generated by this fixed functional appliance therapy seem to vary between studies.[16] Furthermore, there are no studies that have evaluated the effects of mandibular advancement on cervical spine curvature, when using the Forsus™ appliance. Hence, this present study was undertaken.

In our study, a significant change was observed in the SNA and ANB before and after treatment, indicating the dentoalveolar and soft tissues changes caused by the Forsus™ appliance. This finding is congruent with many studies that have shown successful management of Class II malocclusion with the Forsus™ appliance.[17],[18],[19],[20]

However, no significant effect of the Forsus™ appliance on the cervical spine curvature was seen in our study. This result could not be compared with other studies as this is the first study to have explored the effects of a fixed appliance on cervical spine posture. Nevertheless, some authors have studied the effects of removable functional appliances on cervical posture previously. A study by Smailienė et al.[12] measured the effects of the Twin block appliance on body posture and found certain changes in body posture following orthodontic treatment. Since the changes were noticed in both study and control groups, the authors concluded that the changes in body posture were unconnected to orthodontic treatment and improvement in occlusion but were an assertion of physiological growth. A retrospective cephalometric study by Ohnmeiß et al. also suggested that straightening of posture could be a result of physiological growth.[21] However, another retrospective cohort study by Kamal and Fida found that the Twin block appliance used in Class II malocclusion management caused the craniocervical posture to be more erect.[13] A study by Tecco et al. on postural changes with the Frankel Functional Regulator appliance also found an increase in the cervical lordosis angle in the study group following treatment, probably due to a significant backward inclination of the upper segment of the cervical column.[22]

The elucidation of cervical spine images can be difficult, especially in children as a result of the large assortments of normal anatomic variants and synchondroses.[23] Adult proportions of the cervical spine are attained by the time a child is 10–12 years old. However, in our study, participants were between 13 and 18 years of age at the time of recruitment, which means that the major part of the physiologic growth of cervical spine would have been completed. Hence, if we had observed any variations in the cervical spine posture in our study, we could have attributed it to the appliance. However, in our study, we did not find any significant differences between pre-and posttreatment cervical spine measurements based on the cervical curvature angle (OPT/CVT) indicating that orthodontic treatment with the Forsus™ appliance did not have any impact on the cervical spine posture.

While the strength of our study lies in its prospective nature done directly on patients, as compared to many prior studies which just used retrospective records, our study still has some limitations. This study has been done on only one group of patients with Forsus™ appliance, without any comparison group which limits the certainty of its findings. Furthermore, all the factors that can affect the growth in children have not been considered in this study.

   Conclusion Top

It has been hypothesized that a variation in cervical spine posture transpires as a sequel following the mandible being forwardly repositioned. However, within the limitations of our study, no significant differences were found in the spine curvature following Forsus™ appliance therapy. The changes observed here were more of dentoalveolar and soft tissues nature. More long-term and larger sample size studies are needed to confirm the findings.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

   References Top

Michelotti A, Manzo P, Farella M, Martina R. Occlusion and posture: Is there evidence of correlation?. Minerva Stomatol 1999;48:525-34.  Back to cited text no. 1
Solow B, Sonnesen L. Head posture and malocclusions. Eur J Orthod 1998;20:685-93.  Back to cited text no. 2
D'Attilio M, Caputi S, Epifania E, Festa F, Tecco S. Evaluation of cervical posture of children in skeletal class I, II, and III. Cranio 2005;23:219-28.  Back to cited text no. 3
Korbmacher H, Eggers-Stroeder G, Koch L, Kahl-Nieke B. Correlations between dentition anomalies and diseases of the of the postural and movement apparatus – A literature review. J Orofac Orthop 2004;65:190-203.  Back to cited text no. 4
Solow B, Sandham A. Cranio-cervical posture: A factor in the development and function of the dentofacial structures. Eur J Orthod 2002;24:447-56.  Back to cited text no. 5
Bracco P, Deregibus A, Piscetta R. Effects of different jaw relations on postural stability in human subjects. Neurosci Lett 2004;356:228-30.  Back to cited text no. 6
Singh DP, Kaur R. Fixed functional appliances in orthodontics – A review. J Oral Health Craniofac Sci 2018;3:001-10.  Back to cited text no. 7
Shaughnessy T, Shire LH. Etiology of Class II malocclusions. Pediatr Dent 1988;10:336-8.  Back to cited text no. 8
Chen JY, Will LA, Niederman R. Analysis of efficacy of functional appliances on mandibular growth. Am J Orthod Dentofacial Orthop 2002;122:470-6.  Back to cited text no. 9
Atik E, Kocadereli I. Treatment of class II division 2 malocclusion using the forsus fatigue resistance device and 5-year follow-up. Case Rep Dent 2016;2016:3168312.  Back to cited text no. 10
Proffit WR, Fields HW, Sarver DM. Contemporary Orthodontics. 5th ed. St Louis. Mo: Mosby Elsevier; 2007.  Back to cited text no. 11
Smailienė D, Intienė A, Dobradziejutė I, Kušleika G. Effect of treatment with twin-block appliances on body posture in class II malocclusion subjects: A prospective clinical study. Med Sci Monit 2017;23:343-52.  Back to cited text no. 12
Kamal AT, Fida M. Evaluation of cervical spine posture after functional therapy with twin-block appliances: A retrospective cohort study. Am J Orthod Dentofacial Orthop 2019;155:656-61.  Back to cited text no. 13
Alsheikho HO, Jomah DH, Younes M, Tizini M, Hassan H, Khalil F. Evaluation of head and cervical spine posture after functional therapy with Twin-Block and Bionator appliances: A pilot randomized controlled trial. Cranio 2021;11:1-10.  Back to cited text no. 14
Moyers RE, Riolo ML, Guire KE, Wainright RL, Bookstein FL. Differential diagnosis of class II malocclusions. Part 1. Facial types associated with class II malocclusions. Am J Orthod 1980;78:477-94.  Back to cited text no. 15
Zymperdikas VF, Koretsi V, Papageorgiou SN, Papadopoulos MA. Treatment effects of fixed functional appliances in patients with Class II malocclusion: A systematic review and meta-analysis. Eur J Orthod 2016;38:113-26.  Back to cited text no. 16
Nuccio FD, D'Emidio MM, DE Nuccio F. Treatment of class II in adulthood by Forsus FRD device. Oral Implantol (Rome) 2016;9:103-6.  Back to cited text no. 17
Jones G, Buschang PH, Kim KB, Oliver DR. Class II non-extraction patients treated with the Forsus Fatigue Resistant Device versus intermaxillary elastics. Angle Orthod 2008;78:332-8.  Back to cited text no. 18
Cacciatore G, Ghislanzoni LT, Alvetro L, Giuntini V, Franchi L. Treatment and posttreatment effects induced by the Forsus appliance: A controlled clinical study. Angle Orthod 2014;84:1010-7.  Back to cited text no. 19
Franchi L, Alvetro L, Giuntini V, Masucci C, Defraia E, Baccetti T. Effectiveness of comprehensive fixed appliance treatment used with the Forsus Fatigue Resistant Device in Class II patients. Angle Orthod 2011;81:678-83.  Back to cited text no. 20
Ohnmeiß M, Kinzinger G, Wesselbaum J, Korbmacher-Steiner HM. Therapeutic effects of functional orthodontic appliances on cervical spine posture: A retrospective cephalometric study. Head Face Med 2014;10:7.  Back to cited text no. 21
Tecco S, Caputi S, Festa F. Evaluation of cervical posture following palatal expansion: A 12-month follow-up controlled study. Eur J Orthod 2007;29:45-51.  Back to cited text no. 22
Lustrin ES, Karakas SP, Ortiz AO, Cinnamon J, Castillo M, Vaheesan K, et al. Pediatric cervical spine: Normal anatomy, variants, and trauma. Radiographics 2003;23:539-60.  Back to cited text no. 23


  [Figure 1], [Figure 2], [Figure 3]

  [Table 1], [Table 2]


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