Fixed-functional appliance treatment combined with growth hormone therapy

The purpose of this study was to illustrate the effects of growth hormone (GH) therapy and fixed functional appliance treatment in a 13-year-old Class II malocclusion patient without GH deficiency. GH has been shown to effectively increase endochondral growth and induce a more prognathic skeletal pattern. Although a major concern in Class II retrognathic patients is chin deficiency, long-term studies have shown that the mandibular growth enhancement effects of functional appliances are clinically insignificant. This case report demonstrates that the mandible grew significantly during fixed functional appliance treatment combined with GH therapy, with stable results during 2 years 11 months of retention. More studies are needed to evaluate GH therapy as a supplement in Class II treatment.

Highlights

  • Growth hormone therapy affects the growth of the mandibular condyle and the ramus.

  • The Forsus appliance can produce fast overjet correction without patient cooperation.

  • Growth hormone therapy can be helpful in the treatment of Class II retrognathic patients.

When a Class II patient has mandibular growth deficiency, we usually hope to increase mandibular growth to improve the patient’s facial esthetics. However, randomized clinical trials and systematic reviews have shown that it is not possible to effectively increase skeletal growth in children. Some researchers still argue that the effectiveness of mandibular growth treatment depends on the treatment timing, but until now, there have been no long-term studies to support this hypothesis. Thus far, dentoalveolar changes and short-term increases in mandibular growth are the only proven effects of functional appliance treatment.

Human growth hormone (GH) is a polypeptide chain with 188 amino acids that is produced by the anterior pituitary gland. GH deficiency can delay craniofacial growth and tooth eruption. Growth deficiency of the mandible is usually more severe than growth deficiency of the maxilla. GH has been shown to be effective for increasing craniofacial growth in GH-deficient patients, particularly in growth sites with endochondral ossification, such as condylar cartilage. In these patients, GH induced a more prognathic growth pattern.

Children with short stature without GH deficiency have also been treated with biosynthetic GH. However, there has been much controversy regarding the effects of systemic GH administration in patients with familial short stature who are not deficient in GH. Because of the competitive nature of Korean society, GH therapy is frequently recommended by many growth clinics, even to adolescents who are not particularly small or not deficient in GH. There have been attempts to treat malocclusion patients orthodontically while they were simultaneously receiving GH therapy. Case reports of patients with Turner syndrome, pituitary dwarfism, and short stature with a normal GH level have been published, and all have indicated that mandibular growth increased when orthodontic treatment was combined with GH treatment.

Because it has become more difficult to obtain good compliance during orthodontic treatment, compliance-free fixed functional appliances are gaining popularity. Because GH therapy usually increases mandibular growth in GH-deficient patients, and increasing mandibular growth is the major concern of the orthodontist during the treatment of Class II patients with mandibular deficiency, functional appliance treatment combined with GH therapy would be worth assessing. See Supplemental Materials for a short video presentation about this study.

Diagnosis and etiology

A boy, aged 13 years 7 months, came with chief complaints of proclined maxillary incisors and a retruded chin ( Fig 1 ). He had undergone tonsillectomy when he was 7 years old but still suffered from chronic allergic rhinitis and mouth breathing.

Fig 1
Pretreatment intraoral and facial photographs.

Intraoral photographs ( Fig 1 ), study casts ( Fig 2 ), and panoramic radiographs ( Fig 3 ) showed mild dental spacing, large overbite and overjet, flared maxillary incisors, and a lingual crossbite on the right first premolar. Overbite was 4.0 mm, overjet was 5.5 mm, and there was a mild Class II molar relationship on both sides. All teeth other than the maxillary second molars had erupted, and there were no missing or malformed teeth. The patient also had generalized gingival inflammation and poor oral hygiene, but his alveolar bone level was intact. Both temporomandibular joints were well-formed, and there were no specific signs or symptoms.

Fig 2
Pretreatment study casts.

Fig 3
Pretreatment lateral cephalogram, lateral cephalometric tracing, and panoramic radiograph.

In the facial photographs ( Fig 1 ), the patient had a protrusive lip profile and severe lip incompetency. The pretreatment lateral cephalometric radiograph ( Fig 3 , Table ) showed a large ANB angle (7.6°), a protrusive maxilla (A to N perpendicular, 5.8 mm), and a retrusive mandible (Pog to N perpendicular, −5.6 mm). Protrusive, maxillary (U1 to FH, 122.2°) and mandibular incisors (IMPA, 106.2°) were also observed. The American Board of Orthodontics Discrepancy Index score was 30.

Table
Changes in cephalometric measurements
Pretreatment Posttreatment Retention
Bjork sum (°) 393.8 389.9 386.4
Facial height ratio (%) 65.7 70.3 74.3
ANB ( o ) 7.6 4.4 4.1
A to N perpendicular (mm) 5.8 7.7 7.9
Pog to N perpendicular (mm) −5.6 4.2 5.1
U1 to FH ( o ) 122.2 117.3 118.4
U1 to SN ( o ) 112.1 106.3 107.4
L1 to APog ( o ) 7.5 1.6 1.7
IMPA ( o ) 106.2 90.2 93.0
Interincisal angle ( o ) 108.4 133.9 134.0
Nasolabial angle ( o ) 100.8 108.7 112.3
UL to EL (mm) 7.0 1.0 2.5
LL to EL (mm) 6.2 −0.4 1.3

The patient and his parents were aware that his mandible was much smaller than his maxilla. His mother said that because of her son’s short stature, he would start to receive GH treatment soon. His height was 154 cm, much shorter than the average for his age, near the bottom 10%.

Treatment objectives

The treatment objectives were to improve the profile and lip incompetency, correct the lingual crossbite of the right first premolar, establish an ideal interincisor relationship, improve incisor angulation, eliminate interdental spacing, and achieve a functional occlusion with Class I molar and canine relationships.

The prognosis for improvement of chin deficiency seemed to be poor because it was so severe.

Treatment objectives

The treatment objectives were to improve the profile and lip incompetency, correct the lingual crossbite of the right first premolar, establish an ideal interincisor relationship, improve incisor angulation, eliminate interdental spacing, and achieve a functional occlusion with Class I molar and canine relationships.

The prognosis for improvement of chin deficiency seemed to be poor because it was so severe.

Treatment alternatives

Because of the patient’s severely protrusive lip profile, retrusive chin area, and lip incompetence, a significant profile change was required. To improve these conditions, there were several options.

First, maxillary and mandibular first premolar extractions with an orthodontic mini-implant for anchorage reinforcement were considered. This option would allow great profile improvement by causing a large amount of incisor retraction. However, it would not correct the maxillary-mandibular skeletal relationship or the chin deficiency, and there was a risk that it would make the profile too retrusive.

The second option was maxillary and mandibular premolar extractions with intrusion treatment. Intrusion of the posterior teeth using an orthodontic mini-implant or a miniplate can rotate the mandible counterclockwise and improve the chin deficiency. The patient’s overbite was within normal limits, so if autorotation of the mandible was required, intrusion of not only the posterior teeth but also the anterior teeth would have been needed. Total arch intrusion using an orthodontic mini-implant is also possible, but this option was not recommended because the incisal display at rest was not large enough.

The third option was maxillary and mandibular premolar extraction with fixed functional appliance treatment. Because long-term studies on functional appliance treatment have not demonstrated significant growth of the mandible, considerable improvements in mandibular growth in the long term could not be expected. However, temporary enhancement of mandibular growth or a slight restriction of maxillary growth was expected. At the least, rapid improvement of overjet and intermolar relationship could be obtained without the patient’s compliance.

After receiving a detailed explanation of the treatment options, the patient and his parents chose the third option. Although the patient had interdental spacing, extraction of his maxillary and mandibular second premolars was chosen to improve the protrusive lip profile and to compensate for the pushing effect of the fixed functional appliance on the mandibular incisors.

Additionally, we explained the possibility of genioplasty to improve his chin deficiency. A recent study demonstrated that genioplasty in the adolescent period can have good results, so genioplasty can be performed either during orthodontic treatment or after growth completion. The patient and parents did not want a surgical procedure, so we suggested discussing it later if they felt the need after orthodontic treatment.

The patient’s circulating nocturnal GH level was within normal limits, but he and his parents requested GH treatment as a possible means of increasing his height. The mother asked whether the hormone therapy would cause any problems during the orthodontic treatment. I explained that it would not have negative effects. Although I hoped that the patient’s mandibular growth would significantly increase with GH treatment, there was insufficient evidence available on this topic.

Treatment progress

Edgewise metal brackets with 0.022-in slots (MBT setup; 3M Unitek, Monrovia, Calif) were bonded on the buccal surfaces of all erupted teeth except for the maxillary first molars. Bands were placed on the maxillary first molars for the Forsus appliance (3M Unitek). The archwire sequence progressed from 0.014-in nickel-titanium wire to 0.019 × 0.025-in stainless steel working wire, and the patient’s second premolars were extracted during leveling. After alignment, leveling, and lingual crossbite correction, the extraction space was closed with working wire. When the remaining extraction space was about 2 mm, a Forsus appliance with an L-pin was placed at the gingival headgear tube of the first molar, and the hook was soldered distal to the mandibular first premolar. The estimated force vector is shown in Figure 4 ; a greater vertically directed force was applied than what is usually used for Forsus treatment to minimize extrusive tooth movement. The Forsus was used for 8 months.

Dec 19, 2018 | Posted by in Orthodontics | Comments Off on Fixed-functional appliance treatment combined with growth hormone therapy
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