Maxillary Protraction with Miniplates Providing Skeletal Anchorage in a Growing Class III Patient

CASE REPORT Maxillary protraction with miniplates providing skeletal anchorage in a growing Class III patient Bong-Kuen Cha,a Dong-Soon Choi,b Peter Ngan,c Paul-Georg Jost-Brinkmann,d Soung-Min Kim,e and In-san Jangf Gangneung and Seoul, South Korea, Morgantown, WVa, and Berlin, Germany Maxillary protraction headgear has been used in the treatment of Class III malocclusion with maxillary deficiency. However, loss of dental anchorage has been reported with tooth-borne anchorage such as lingual arches and expansion devices. This side effect can be minimized with skeletal anchorage devices such as implants, onplants, mini-implants, and miniplates. The use of miniplates for maxillary protraction in the mixed dentition has not been reported in the literature. This case report describes the treatment of an 8-year-old girl with a Class III malocclusion and maxillary deficiency. Miniplates were used as skeletal anchorage for maxillary protraction followed by phase 2 orthodontic treatment with fixed appliances. Skeletal, dental, and facial changes in response to orthopedic and orthodontic treatment are reported to illustrate the esthetics, function, and stability of treatment with this new technique. (Am J Orthod Dentofacial Orthop 2011;139:99-112) axillary protraction headgear has been used in loss of anchorage, especially when preservation of arch Mthe treatment of Class III patients with maxillary length is necessary, and the inability to apply orthopedic retrusion. Clinical studies have shown that 2 to force to the maxilla directly. Many investigators have 4 mm of maxillary advancement can be obtained with 8 attempted to design an absolute anchorage system for to 12 months of maxillary protraction. This is the result maxillary protraction including the use of intentionally of a combination of forward movement of the maxilla, ankylosed maxillary deciduous canines, osseointegrated downward and backward rotation of the mandible, labial titanium implants, onplants, miniscrews, and mini- tipping of the maxillary incisors, and lingual tipping of plates.6-9 Each implant system has strengths and the mandibular incisors.1-5 Most of these studies used weaknesses. Miniplates, for example, have been used tooth-borne anchorage devices such as a lingual arch, with success for a variety of orthodontic anchorage quad helix, or maxillary expansion appliance.1-3 The needs including intrusion of posterior molars, corre- disadvantages of tooth-borne anchorage devices are ction of anterior open bite, retracting mandibular molars, and treatment of patients with maxillary 10 aProfessor, Department of Orthodontics, College of Dentistry, Research Institute hypoplasia. Surgical or titanium miniplates are gaining of Oral Science, Kangnung National University, Gangneung, South Korea. popularity as an orthodontic implant anchor because they bAssistant professor, Department of Orthodontics, College of Dentistry, Research have been proven safe and effective for fractures and Institute of Oral Science, Kangnung National University, Gangneung, South Korea. osteotomies, and they can be placed above the tooth cProfessor and chair, Department of Orthodontics, School of Dentistry, West roots to facilitate orthodontic tooth movement. The use Virginia University, Morgantown. of miniplates in the treatment of maxillary hypoplasia dProfessor, Department of Orthodontics and Dentofacial Orthopedics, Center for Dental and Craniofacial Sciences, Charite, Universitatsmedizin Berlin, Berlin, in growing Class III patients has not been reported in Germany. the literature. This case report illustrates the use of surgi- eAssociate professor, Department of Oral and Maxillofacial Surgery, School of cal miniplates as anchorage for maxillary protraction in Dentistry, Seoul National University, Seoul, South Korea. fResearch fellow, Department of Orthodontics, College of Dentistry, Kangnung the mixed dentition. National University, Gangneung, South Korea. The authors report no commercial, proprietary, or financial interest in the products or companies described in this article. DIAGNOSIS AND ETIOLOGY Reprint requests to: Peter Ngan, Department of Orthodontics, West Virginia University School of Dentistry, Health Science Center North, PO Box 9480, The patient, an 8-year-old girl, came to the Kang- Morgantown, WV 26506; e-mail, [email protected]. nung National University Orthodontic Clinic in Gang- Submitted, December 2008; revised and accepted, June 2009. neung, South Korea, with a chief concern of “my bite 0889-5406/$36.00 ” fi Copyright Ó 2011 by the American Association of Orthodontists. is not right. Clinically, she had a concave facial pro le, doi:10.1016/j.ajodo.2009.06.025 and acute nasolabial angle, and a protrusive mandible 99 100 Cha et al Fig 1. Pretreatment photographs. (Fig 1). Intraorally, she had an anterior crossbite and reason, our treatment consisted of phase 1 orthopedic a low anterior tongue posture. The maxillary right first treatment to protract the maxilla with a skeletal an- deciduous molar and left second deciduous molar had chorage system. Surgical miniplates were used as an- exfoliated prematurely, and midarch crowding was chorage instead of the conventional tooth-borne noted on the dental casts and panoramic radiograph. appliances to prevent possible mesial movement of The cephalometric radiograph and tracing showed the posterior dentition. The objective of this early a skeletal Class III malocclusion with maxillary defi- phase of treatment was to induce harmonious growth ciency, mandibular prognathism (ANB, –2.2), and of the maxilla with improvement in facial esthetics. a normal mandibular plane angle (FMA, 23). The max- Overcorrection of the maxilla to an overjet of 3 to 4 illary incisors were proclined (U1 to FH, 109), and the mm was desirable to anticipate excessive growth of mandibular incisors were retroclined (IMPA, 86), com- the mandible during the pubertal growth spurt. The pensating for the skeletal malocclusion (Figs 2 and 3, patient was followed for a period of time to determine Table). There was no family history of mandibular whether the malocclusion could be camouflaged by or- prognathism. thodontic tooth movement. The phase 2 treatment was initiated at 11 years of age for 18 months to correct TREATMENT OBJECTIVES the remaining crowding, overjet, and overbite prob- In determining our treatment objectives, we asked lems. The patient was placed in retention for 27 the patient whether she was willing to undergo a surgi- months after fixed appliance therapy to determine cal operation. She was willing if necessary. For that the stability of treatment without orthognathic surgery. January 2011 Vol 139 Issue 1 American Journal of Orthodontics and Dentofacial Orthopedics Cha et al 101 Fig 2. Pretreatment dental casts. TREATMENT ALTERNATIVES an atraumatic subperiosteal dissection to the infrazygo- Based on the objectives, 2 treatment options were matic crest, a curvilinear miniplate was adapted, bent to ’ fi proposed. The first option was an early phase of ortho- the zygomatic buttress s bony surface, and xated with 3 pedic treatment to induce harmonious skeletal growth self-tapping miniscrews per side (Fig 5, A). From our and improve facial esthetics followed by phase 2 treat- experience, at least 3 to 4 screws should be placed to re- ment to correct the remaining crowding, overjet, and sist the maxillary protraction force of about 300 to 400 overbite problems. This option would not eliminate cN per side. Screw placement should be in a posterior- the necessity for orthognathic surgery. The patient superior direction to prevent damage to the premolar would be followed to determine the stability of treat- tooth follicles (Fig 5, B). The end of the miniplate fi ment. The second option would be to wait until all entered the oral cavity between the canine and rst pre- growth was completed and determine whether the mal- molar area in the keratinized attached gingiva to prevent occlusion could be camouflaged by orthodontic treat- gingival irritation. The oral portion of the miniplate was fi ment or a combination of surgical and orthodontic modi ed into a hook for elastic traction. treatment. Maxillary protraction was started 2 weeks after placement of the miniplates, with a force of 300cN per side TREATMENT PROGRESS applied 12 to 14 hours per day (Fig 6). Within 10 months Phase 1 treatment was started at age 8 years 4 of treatment, a three quarters premolar width Class II months with a maxillary removable appliance to regain molar relationship was established. Thereafter, the space lost from the early loss of the deciduous molars patient’s wearing of protraction headgear was limited (Fig 4). After 6 months of observation, a surgical mini- to nighttime only as a retainer for 10 months. The plates plate was placed. Local infiltration anesthesia was were removed after the facemask treatment. A mucoper- administered to the maxillary left and right buccal iosteal incision and a subperiosteal dissection were vestibular areas after surgical disinfection. A vestibular performed to expose the miniplate. The monocortical incision around the canine area was performed. After screws were removed first, and the miniplate was then American Journal of Orthodontics and Dentofacial Orthopedics January 2011 Vol 139 Issue 1 102 Cha et al Fig 3. Pretreatment radiographs and tracing. Table. Cephalometric measurements at pretreatment, after protraction headgear treatment, after fixed appliance treatment, and 27 months after removal of the fixed appliance After protraction After fixed

Load more