|Year : 2012 | Volume
| Issue : 1 | Page : 56-65
Treatment of skeletal class II division 1 malocclusion with mandibular deficiency using myofunctional appliances in growing individuals
Y Pachori1, M Navlani2, T Gaur3, S Bhatnagar4
1 Department of Orthodontics, Jodhpur Dental College and General Hospital, Jodhpur, India
2 Department of Orthodontics, Modern Dental College and Research Centre, Indore, Madhya Pradesh, India
3 Department of Orthodontics, Government Dental College, Jaipur, Rajasthan, India
4 Department of Pedodontics and Preventive Dentistry, Jodhpur Dental College and General Hospital, Jodhpur, India
|Date of Web Publication||3-May-2012|
A 36, Vidhya Nagar, Near Jagatpura Railway Crossing, Jagatpura, Jaipur - 302 025, Rajasthan
| Abstract|| |
Class II division 1 malocclusion is the most common malocclusion seen in day-to-day practice. The majority of the patients with class II division 1 malocclusions have the presence of underlying skeletal discrepancy between maxilla and mandible. The treatment of skeletal class II division 1 depends upon the age of the patient, growth potential, severity of malocclusion, and compliance of patient with treatment. Myofunctional appliance can be successfully used to treat growing patients with class II division 1 malocclusion having retrusive mandible. This article presents a discussion on treatment of class II division 1 due to mandibular deficiency with growth modification approach using myofunctional appliances and a series of three case reports of treatment of skeletal class II division 1 malocclusion using myofunctional appliance followed by fixed mechanotherapy.
Keywords: Class II malocclusion, growth modification, myofunctional appliance
|How to cite this article:|
Pachori Y, Navlani M, Gaur T, Bhatnagar S. Treatment of skeletal class II division 1 malocclusion with mandibular deficiency using myofunctional appliances in growing individuals. J Indian Soc Pedod Prev Dent 2012;30:56-65
|How to cite this URL:|
Pachori Y, Navlani M, Gaur T, Bhatnagar S. Treatment of skeletal class II division 1 malocclusion with mandibular deficiency using myofunctional appliances in growing individuals. J Indian Soc Pedod Prev Dent [serial online] 2012 [cited 2014 Oct 21];30:56-65. Available from: http://www.jisppd.com/text.asp?2012/30/1/56/95584
| Introduction|| |
Among the various types of malocclusion found in human population, class II division 1 is one of the most common. According to Dr. James McNamara,  mandibular retrusion is the most common feature of class II division 1 malocclusion in growing children. Class II malocclusion is found in 15% of population in the world. Class II division 1 malocclusion is often complicated by the presence of underlying skeletal discrepancy between maxilla and mandible. It can be due to protrusive maxilla, retrusive mandible, or a combination of both. The treatment of class II division 1 depends upon the age of the patient, growth potential, severity of malocclusion, and compliance of patient for treatment. , In growing individuals, growth modification procedures can be carried out to correct the skeletal class II malocclusion, during mixed or early permanent dentition before the cessation of active growth. In patients who are at the end of prepubertal growth spurt or who are uncooperative, fixed functional appliances like Herbst, Forsus-FRD or Jasper Jumper can be used. In patients with mild to moderate skeletal class II, where active growth is completed, it is not possible to undertake growth modification procedures. In such condition, underlying skeletal discrepancy can be camouflaged by orthodontic tooth movement with extraction or without extraction (depending upon the severity of malocclusion). In adult patients where the discrepancy is very severe, the best treatment approach is combined orthodontic and orthognathic surgery. ,,,
Growth modification is the interceptive mode of treatment modality in developing class II skeletal conditions. The goal of growth modification is to alter the unacceptable skeletal relationship by modifying the patient's remaining facial growth favorably to change the size, orientation, and position of the jaws. In this article, we discuss the treatment modality for class II division 1 malocclusion in growing patients.
| Case Reports|| |
A 10-year-old male patient reported in good health with chief complaint of protrusion of upper front teeth and unpleasant looks. The dental and medical history was unremarkable. Extraoral [Figure 1]a examination showed convex facial profile with posterior divergence of the face due to retrognathic mandible. Lips were potentially competent and protrusive with 6 mm of interlabial gap, everted lower lip, and hypotonic upper lip. Intraoral [Figure 1]b examination revealed late mixed dentition stage with erupting upper canine and nearly exfoliating second deciduous molar on the left side. Dental arches were "U" shaped and maxillary anteriors were proclined with spacing. The mandibular incisors were impinging on palatal tissue on closure. In occlusion, there was a class II division 1 relationship with increased overjet of 11 mm and overbite of 8 mm. The molar relationship was class II bilaterally, with scissor bite in relation to 14 and 44.
|Figure 1a: pretreatment extra-oral photographs|
Figure 1b: Pre-treatment intra-oral photographs
Figure 1c: Pre-treatment radiographs
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The lateral cephalogram [Figure 1]c showed a severe skeletal ANB difference of 7°. The maxilla was normal relative to the cranial base with an SNA at 80°. The mandible was retrognathic with an SNB value of 73°. The maxillary incisors were proclined.
Diagnosis: Skeletal class II jaw relationship with Angle's class II division 1 malocclusion with average growth pattern. Hand wrist radiograph was taken to confirm the growing status of patient.
Treatment plan: Growth modification with myofunctional appliance therapy (activator) followed by final detailing of occlusion with fixed pre-adjusted edgewise appliance.
The objectives of growth modification procedure (myofunctional appliance) were to reduce the skeletal class II pattern, achieve a class I skeletal and dental relation, establish normal overjet and overbite, reduce the convex profile, and improve the lip incompetency. Myofunctional appliance (Activator) was planned for growth modification therapy. Patient was instructed to wear the activator for 14 hours/day.
Results achieved: Patient's soft tissue facial profile was improved, along with lip incompetency, reduction of the severe overjet and deep impinging overbite, and achievement of class I skeletal and dental relationships [Figure 2]a. The cephalometric [Figure 2]b analysis after myofunctional therapy demonstrates favorable forward growth of the mandible. There was a reduction of the skeletal class II with a 5° decrease in the ANB angle through forward growth of the mandible. The post-treatment value of SNB at 79° indicates the advancement of mandible.
|Figure 2a: Post-functional intra-oral photograph|
Figure 2b: Post-functional radiograph
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At the end of treatment, the patient had pleasing soft tissue profile [Figure 3]a and well-settled dentition [Figure 3]b. Comparison of pre-treatment and post-treatment cephalometric values is given in [Table 1]. Total treatment time was 22 months.
|Figure 3a: Post-treatment extra-oral photograph|
Figure 3b: Post-treatment intra-oral photographs
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|Table 1: Pre-treatment, mid-treatment, and post-treatment cephalometric values of case 1|
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An 11-year-old girl patient presented with the chief complaints of more visibility of upper front teeth and difficulty in closing lip. Extraoral [Figure 4]a examination showed mesoprosopic facial form, convex facial profile with potentially competent and protrusive lips with 5 mm of interlabial gap, hypotonic upper lip, everted lower lip, retrognathic mandible, and reduced lower facial height. Intraoral [Figure 4]b examination revealed well-aligned arches, proclination of upper incisors with increased overjet of 9 mm, and deep bite of 8 mm. There was a class II molar relation and class II canine relation. Upper dental midline was coinciding with facial midline, but lower dental midline shifted to the right side by 2 mm. There was mild spacing in lower anterior teeth and curve of Spee of 3 mm on either side.
|Figure 4a: Pretreatment extra-oral photographs|
Figure 4b: Pre-treatment intra-oral photograph
Figure 4c: Pre-treatment radiographs
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The lateral cephalogram [Figure 4]c showed skeletal ANB difference of 6°. The maxilla was normal relative to the cranial base with an SNA at 81°. The mandible was retrognathic with an SNB at 75°. The maxillary and mandibular incisors were normally positioned to the apical base upper incisor to NA (6 mm, 24°), lower incisor to NB (6 mm, 28°). The patient had horizontal growth pattern.
Skeletal class II due to short and posteriorly placed mandible with horizontal growth pattern, dental Angle's class II division1 malocclusion.
Growth modification with myofunctional (twin block) [Figure 5]a appliance to advance the retrognathic mandible, followed by fixed mechanotherapy for final detailing of occlusion.
|Figure 5a: After functional appliance therapy: Twin block appliance in place|
Figure 5b: After functional appliance therapy: Post-functional intra-oral photograph
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Saggital correction (class I) was achieved through growth modification by myofunctional appliance [Figure 5]b and there was improvement in the facial profile and lip incompetency [Figure 6]a and reduction of the severe overjet and deep overbite. Evaluation of the cephalometric tracings demonstrates reduction of the skeletal class II with a 3° decrease in the ANB angle through forward growth of the mandible. The post-treatment value of SNB was at 78°.
At the end of the treatment, the patient had very good facial profile, competent lips class I molar and canine relationship, normal overjet and overbite [Figure 6]b, root parallelism, and normal tooth position [Figure 6]c. Comparison of pre-treatment and post-treatment cephalometric values is given in [Table 2]. Treatment duration was 18 months.
|Figure 6a: Post-treatment extra-oral photograph|
Figure 6b: Post-treatment intra-oral photographs
Figure 6c: Post treatment radiographs
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|Table 2: Pre-treatment, mid-treatment, and post-treatment cephalometric values of case 2|
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An 11½-year-old boy patient reported with the chief complaints of forwardly placed upper front teeth and unpleasant looks. Extraoral [Figure 7]a examination revealed a convex profile mainly due to retrognathic mandible, incompetent protrusive lips with 7 mm of interlabial gap, upturned prominent nose, deep mentolabial sulcus, and lower lip trap habit. Intraoral examination [Figure 7]b of dentition revealed mixed dentition stage. Maxillary and mandibular arch were ovoid in shape with proclined upper incisors and generalized spacing. In occlusion, there was Angle's class II division 1 relationship with overjet of 13 mm. The overbite was 6 mm. The molar relationship was class II bilaterally. Canine relationship was class II on the right side and was not established on the left side. Upper and lower dental midlines were coinciding with each other and with facial midline.
|Figure 7a: Pre treatment extra-oral photographs:|
Figure 7b: Pre-treatment intra-oral photographs
Figure 7c: Pre-treatment radiographs:
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The lateral cephalometric values [Figure 7]c showed a convex hard tissue profile with a severe skeletal ANB difference of 7°. The maxilla was slightly prognathic relative to the cranial base with an SNB at 83°. The mandible was retrognathic relative to the cranial base with an SNB at 76°. There was proclination of upper and lower incisors with average growth pattern.
Angle's class II division 1 dentoalveolar malocclusion on class II skeletal base due to retrognathic mandible.
Growth modification with myofunctional appliance therapy (activator) [Figure 8]a immediately followed by final detailing of occlusion with fixed pre-adjusted edgewise appliance was planned.
|Figure 8a: Activator in place|
Figure 8b: Post-functional intra-oral photograph
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Saggital correction (skeletal class I) was achieved through growth modification [Figure 8]b with improvement in the facial profile and lip incompetency and reduction of the severe overjet and deep overbite. At the end of the treatment, the patient had very good facial profile [Figure 9]a, class I molar and canine relationship, normal overjet and overbite [Figure 9]b, root parallelism, and normal tooth position. Evaluation of the cephalometric [Figure 9]c tracings demonstrates reduction of the skeletal class II with a 4° decrease in the ANB angle through forward growth of the mandible. The post-treatment value of SNA was 82° and of SNB was 79°. Proclination of upper as well lower incisors was also corrected. Comparison of pretreatment, mid treatment and post treatment Cephalometric values is given is [Table 3].
|Figure 9a: Post treatment extra-oral photograph|
Figure 9b: Post-treatment intra-oral photographs
Figure 9c: Post-treatment radiographgraphs (just before debonding)
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|Table 3: Pre-treatment, mid-treatment, and post-treatment cephalometric values of case 3|
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| Discussion|| |
Majority of Class II division 1 patients have a normally positioned maxilla but a smaller and more retruded mandible. Class II malocclusion characterized by mandibular deficiency can be successfully treated, during active growth phase, with the use of myofunctional appliances to advance the mandible. Facial esthetics in such patients is compromised due to more convex profile, lip incompetency, more display of upper teeth, and posteriorly placed lower jaw. Reduction in facial convexity and straighter profiles resulting in improved esthetics is a treatment objective in these cases. Functional appliances can be removable and fixed devices, which alter the position of the mandible, both sagittally and vertically, by inducing the supplementary lengthening of the mandible by stimulating increased growth at the condylar cartilage. There are a number of myofunctional appliances, which can be used to correct mandibular retrusion. Each proponent of the different functional appliances has conceived more or less his own concept and working hypothesis: Andresen, Haupl, and Petrik, Herren, and Harvold for the activator; Balters for the bionator; Frankel for the functional regulator; Stockfish for the kinetor; and Bimler for the Gebissformer. Removable myofunctional appliances such as activator, bionator, twin block, Frankel, etc. can be used to advance the mandible. ,,,,,,,,
Functional appliance work in two ways. 1). Force application: Functional appliance apply force, stain on structures involved and causes alteration in shape and size. This alteration ultimately leads to secondary adaptation in function. 2). Force elimination: Elimination of abnormal and restrictive force to allow growth and development of the area. The principle of action of functional therapy is based on the hypothesis that imbalance in neuromuscular forces results in malocclusions. Functional appliances dictate the new pattern of function leading to development of new morphological pattern [acceptable relation of the jaws, changes in the amount and direction of growth of the jaws, an improved occlusion and proper arrangement of the teeth]. Functional appliances correct the muscular imbalance, soft tissue tone and function in oro-naso-pharyngeal complex. Functional appliances are mainly orthopedic in nature and influence the facial skeleton of growing children in condylar and sutural areas. Principle of functional appliance therapy is to reposition a retrognathic lower jaw to a forward position with the help of myofunctional appliance, made after a protrusive bite registration. Myofunctional appliances for mandibular advancement in the treatment of class II work by encouraging the functional displacement of mandibular condyles in downward and forward direction. Adaptive remodeling occurs in articular surface of temporomandibular joint (TMJ) to improve the position of mandible in relation to maxilla. Functional appliances also influence the eruption of the posterior and anterior teeth. When upper anterior teeth are prohibited from erupting, while the lower posterior teeth are erupting up and forward, the resulting rotation of the occlusal plane and forward movement of the dentition contributes to the correction of class II relationship. The effect on maxilla, although small, is almost always observed along with any mandibular effects. When the mandible is held forward, the elasticity of the soft tissues produces a reactive force against the maxilla and restraint of maxillary growth occurs, helping in the correction of class II tendency. ,,
Over the years, the use of functional appliances has received mixed results. It is important to note that functional appliance therapy is to be generally followed by the traditional full fixed appliance treatment for optimum results, since they deal more with the gross changes in the intermaxillary relations and arches. Functional appliances are not designed for precise individual tooth movements.
| Conclusion|| |
For children with moderate to severe class II division 1 malocclusion problems, growth modification is a successful approach. Mandibular retrognathism can be successfully treated by myofunctional appliances. Whenever required, it can be followed by comprehensive fixed appliance treatment for detailing of occlusion. Patient cooperation and repeated motivation is a critical factor while trying for growth modification in adolescent children. Case selection and diagnosis is critical. Manipulation of appliance, growth amount, and direction are the major factors to be considered.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9]
[Table 1], [Table 2], [Table 3]