Correction of Class II Malocclusion Using Fixed Functional Appliance For Adolescent Patients – A Case Report

Laxmi Pritha M, Ramya Chandran, Anil Kumar, Amal S Nair

Department of Orthodontics, Sree Mookambika Institute of Dental Sciences, Kulasekharam, Kannyakumari District.

Received : 11-01-2022

Revised : 07-02-2022

Accepted : 22-02-2022

Address for correspondence:

Dr Laxmi Pritha M, Post Graduate, Department of Orthodontics, Sree Mookambika Institute of Dental Sciences, Kulasekharam, Kannyakumari district.

E-mail : laxmipritha@gmail.com

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How to cite this article:

Pritha L M, Chandran R, Kumar A, Nair A S. Correction of Skeletal Class II Malocclusion Using Fixed Functional Appliance for Adolescent Patients – A Case Report. J Oral Biomed Sci 2022;1:34-40.

 Abstract:

For an efficient and effective treatment of skeletal Class II malocclusion is by interceptive approach during the pubertal growth stage. When considering early Class II therapy psychosocial issues and a greater risk of dental trauma are certain factors that should be addressed. This case report is on a patient who underwent orthodontic treatment due to aesthetic discomfort with the incisors protrusion. As the patient was in the circumpubertal stage, it was decided to try a different approach of treatment. This case report is on Herbst appliance and fixed multibrackets therapy during the circumpubertal stage, resulting in an adequate outcome.

Keywords: Skeletal Class II malocclusion, Herbst appliance

 Introduction:

Despite favorable skeletal base change, untreated Class II malocclusions do not appear to be self-corrective at the occlusal level. Non-extraction Class II treatment regimens can generally be divided into 2-phase treatment 1,2 which involves the use of a functional appliance followed by multibracket appliances, or alternatively, a single-phase treatment involves Class II mechanics (ie, Class II elastics) concurrent with fixed appliance therapy. 3-6 Two-phase treatment has been associated with an acceleration but not an increase in absolute mandibular length, increased overall treatment times, and a relapse of the dentoalveolar movements when compared with a treatment protocol that does not involve the use of a functional appliance. 7-8

Emil Herbst in 1905 introduced the Herbst appliance, it is a rigid noncompliant intermaxillary appliance9 which is designed to keep the mandible in a continuous protrusive pathway using anchorage from maxillary and mandibular dentitions by means of bilateral telescopic arms.10

This continuous “bite jumping” is maintained still permitting the opening and lateral excursive movements involved while eating and speaking.11,12 Closure of the mouth can only occur with the mandible in a protruded position.13 It has been proposed that this protrusion induces the condylar growth by stimulation as an adaptive response to the forward positioning of the mandible, with the possibility of some degree of mandibular growth redirection.14

Case report:

A 16-year-old boy reported to the Department of Orthodontics and Dentofacial Orthopaedics with a chief complaint of forwardly placed teeth in upper front tooth region. On extraoral examination, he had a convex profile with a retrognathic   mandible, posterior divergence, obtuse nasolabial angle, deep mentolabial sulcus, high clinical FMA with potentially incompetent lips. On intraoral examination, he had Angle’s class II malocclusion, End on canine relation on both sides, scissor bite in relation to 25,35.

The panoramic radiograph showed no missing teeth or pathologies with horizontally impacted third molar. Cephalometric analysis indicated a skeletal class II due to posteriorly positioned mandible along with a vertical growth pattern with upper and lower incisor proclination.

Treatment objectives:

Correction of skeletal class II.

Correction of proclined upper and lower incisors.

Correction of overjet and overbite.

Obtaining a Class I molar relationship.

Achieving a pleasant soft tissue profile.

Treatment plan:

Early phase of orthopedic treatment was planned to induce harmonious skeletal growth and improve facial esthetics. The Twin Block could have been planned but considering the age factor Herbst was recommended. Fixed orthodontic mechanotherapy might be needed later on for the final detailing of occlusion.

Treatment progress:

The patient is treated with acrylic splint herbst appliance comprises of upper and lower splints.

Upper acrylic splint is composed of 0.045 elgiloy wire framework bent to fit the maxillary work model. The palatal arch is formed by placing an omega loop in the center of the dental arch between the second premolar and the first permanent molar. A lateral bend is then made at the gingival margin of the upper first premolar, bringing it through the interproximal space. Along the buccal surface of the canines and first premolars the wire is contoured posteriorly. The wire is then curved through the interproximal space distal to the first molar and brought anteriorly along the lingual surface of that tooth. The wire is kept 1 mm away from the tooth surfaces above the gingival margin. A similar configuration is used on the opposite side.

The framework of the lower splint is formed on the mandibular model with 0.040-inch Elgiloy wire that is contoured along the lingual surface of the lower six anterior teeth. The wire then passes through the interproximal surface distal to  the canine and then distally along the buccal surfaces of the teeth interproximal space. The wire is contoured posteriorly along the buccal surface of the canines and first premolars. The wire then is curved through the interproximal space distal to the first molar and brought anteriorly along the lingual surface of that tooth. The wire is kept approximately 1 mm away from the tooth surfaces just above the gingival margin. A similar configuration is used on the opposite side.

The framework for the lower splint is formed on the mandibular work model by means of 0.040 inch Elgiloy wire that is contoured along the lingual surface of the six lower anterior teeth The wire then passes through the interproximal surface distal to the canine and passes distally along the buccal surfaces of the teeth. It then curves around the distal surface of the first molar and follows the lingual contour of the posterior dental segment.15The appliance can be compared to an artificial joint working between the maxilla and the mandible. A bilateral telescope mechanism attached to orthodontic bands keeps the mandible mechanically in a continuous anteriorly jumped position. Each telescope device consists of a tube, a plunger, two pivots, and two screws. The pivot for the tube is usually soldered to the maxillary permanent first molar band, and the pivot for the plunger to the mandibular first premolar band. The screws prevent the telescoping parts from slipping. The amount of bite jumping is determined by the length of the tube. Usually the mandible is retained in an end-to-end incisal relationship. In order to prevent it from slipping out of the tube when the mouth is opened wide the length of the plunger is kept at a maximum. If the plunger is too long it may protrude far behind the tube and injure the buccal mucosa distal to the maxillary permanent first molar. The mechanism permits vertical opening movements and, when properly constructed.16The tube with axle and screw was inserted into the upper acrylic component. The plunger with axle and screw was inserted into the lower acrylic component.15

Conclusion:

In the treatment of Class II malocclusions, the Herbst appliance is most effective. In brachyfacial growth pattern, subject’s treatment prognosis is best. The potential risk factors for occlusal relapse are unfavorable growth, unstable   occlusal conditions, and oral habits that persist after treatment. Post treatment retention with a removable functional appliance is therefore recommended as treatment with the Herbst appliance as it is performed during a relatively short period, the hard and soft tissues (teeth, bone, and musculature) will need some time for re-adaptation to the new mandibular position after the appliance is removed. 15

In treated adolescents patients with Herbst appliance an increase in the anteroposterior length of mandible, increased  vertical height of ramus, increase in lower facial height, mandibular incisor proclination, mesial movement of lower molars, distal movement of upper molars also about the increase in mandibular prognathism accomplished by herbst therapy seems in particular to be a result of condylar and glenoid fossa remodeling, while condyle fossa relationship changes is of less importance. 17

Conflict of interest:

Nil

Financial support and sponsorship:

Nil

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Fig 1: Pretreatment photographs

Fig 2: Pretreatment radiographs

Fig 3: Acrylic splint Herbst appliance

Fig 4: Post insertion pictures

Fig 5: End of Phase I

Fig 6: End of Phase I – Lateral cephalogram and OPG

Fig 7: End of Phase I – Superimposition (Black – Pretreatment, Blue – End of Phase I)