Anatomic differences of the primary dentition may hinder traditional methods of intermaxillary fixation. Furthermore, the presence of both the primary and permanent dentition can complicate establishing, and maintaining, the preinjury occlusion. The treating surgeon must be aware of these differences for optimal treatment outcomes. This article discusses and illustrates methods that facial trauma surgeons can use to establish intermaxillary fixation in children aged 12 years and younger.
Key points
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Do not use intermaxillary fixation screws in children because damage to the developing teeth is likely.
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Traditional arch bars may not be useful. Consider Risdon cable use, especially for those patients in the primary dentition.
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Use of elastics for maxillomandibular fixation is preferable over wires.
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Appreciate the key anatomic differences of the primary dentition.
Introduction
As society has progressed, so too have the mechanisms of trauma to the maxillofacial complex. As such, the management of craniomaxillofacial trauma has evolved gradually over time. Much of these changes were facilitated by the devastating injuries encountered during World War I and World War II. The studies of Kanzanjian, Converse, Gillies, and Millard are a testament to some of the great advances observed during this time. The principles established by the aforementioned surgeons were further advanced by Rowe, Kiley, Curtis, Ivy, and Dingman in the midtwentieth century. During this same relative time period, there was a tremendous contribution by Paul Tessier, who established the fundamental principles of surgical reconstruction of pediatric craniofacial deformity, most notably in Crouzon and Apert syndrome. The common thread throughout the past 150 years of facial fracture treatment has been the understanding of the precise relationship of the teeth and how to recapitulate the preinjury occlusion. That is, if the surgeon places the teeth in their proper position, the bone generally follows. This same concept holds true for the management of pediatric mandible fractures. The definition of pediatric is somewhat variable, the focus of this article will be patients in the primary and mixed dentition, approximately aged 12 years and younger.
General considerations
Anatomy of the Growing Mandible, Stages of Dentition, and Fracture Patterns
Although these general principles are discussed in detail by other articles in this issue, the discussion of intermaxillary fixation in children would not be complete without the mention of general anatomic and epidemiologic issues. During early development the thick periosteum and mandibular bone has a robust inherent osteogenic potential. This characteristic, along with the large medullary space and thin cortical walls of the mandible, yield much greater elasticity. This, in turn, results in a higher amount of greenstick fractures that are almost exclusively seen in pediatric patients. During the first few years of life, tooth buds make up a small percentage of the mass of the maxilla and mandible. However, as development occurs and the primary dentition and developing permanent dentition occupy the space of the mandible, the mandible is weakened, which facilitates fractures through these areas. Fundamental to understanding intermaxillary fixation is through a thorough understanding of the dentition. Pediatric mandible fractures can be divided into the stage of dentition of the patient; that is, fractures occurring during primary dentition, mixed dentition, or permanent dentition. The stage of dentition can greatly influence the modality to achieve intermaxillary fixation.
The tooth buds of the primary teeth are present as early as 12 weeks in utero. The first teeth to erupt are usually the lower central incisors at 6 to 10 months of age. By 3 years of age, all 20 primary teeth are erupted. The pediatric dentition is characterized by short, bulbous crowns with different height of contours as compared with adult teeth. It is normal for the primary dentition to have spacing between each tooth, which allows for the eruption of the permanent dentition but also complicates traditional methods of intermaxillary fixation (ie, Erich Arch Bars, discussed later).
The mixed dentition begins at approximately 6 years of age with the eruption of the first permanent molar. The last primary tooth exfoliates at approximately 12 years of age. The simultaneous eruption of permanent teeth and exfoliation of primary teeth can lead to difficulty in establishing the proper occlusion and placement of interdental wires or arch bars. This combination can hinder mandibular fracture reduction for both open and closed treatment. As the child progresses into the teenage years and adolescence, surgical management of facial fractures and intermaxillary fixation techniques more closely resemble those of adults.
The mandibular fracture patterns seen in the pediatric population vary based on the stage of dentition. , The mandibular condyle is the most frequently fractured region of the pediatric mandible, generally ranging anywhere from 7% to 45%. This is followed closely by fractures of the parasymphysis, ranging 20% to 32% of fractures. Finally, mandibular angle fractures can range from 4.4% to 45%; however, this incident increases with the development of the third molar from the teenage years into early adulthood. Potential treatment options for pediatric mandible fractures can range from observation, a short period of MMF and physical therapy, closed treatment with interdental wiring/arch bars and elastics, and open reduction and internal fixation. If anything other than observation is chosen, the surgeon must decide on the method of interdental and/or intermaxillary fixation.
Methods of interdental and intermaxillary fixation in the primary and mixed dentition
Methods of interdental and intermaxillary fixation in the primary and mixed dentition include Risdon cables, Erich arch bars, Ivy loops, sutures, and acrylic dental splints among other. Each of these treatment options has its own pros and cons. In addition, observation/nonsurgical management alone is often a prudent choice by the clinician ( Fig. 1 ).
Direct Interdental Wiring
Direct interdental wiring is a simple, noninvasive way to aid in fracture reduction. In its simplest form, a bridle wire can be placed around the cervical margin of teeth adjacent to the mandible fracture to aid in reduction. In the pediatric patient, special care should be taken to not to avulse teeth. The wire can be left in place for 2 to 3 weeks, often in conjunction with arch bars or Risdon cables to help stabilize the fracture. The wire can be removed with ease in the office without the use of general anesthesia. Bridle wires are not a good option in children aged younger than 3 years. Patients in the primary and mixed dentition phases, roughly aged 3 to 12 years, the bridle wire method can be used but as stated earlier, the anchoring teeth must be stable. , The authors use this technique often, especially as a temporary stabilization method before definitive treatment in the operating room but generally in the late mixed dentition or permanent dentition.
Risdon Cables
Risdon cables are an ideal method to provide stabilization of the dentition and provide a mechanism to facilitate maxillomandibular fixation ( Fig. 2 ). The indications for the Risdon cable application include patients in the primary and mixed dentition that require stabilization of the dentoalveolar complex, a mechanism for elastics to hook on to, or an arch bar for maxillomandibular fixation. , , , The original description by E. Fulton Risdon, Canada’s first plastic surgeon, used a thick, 1-mm, wire that was twisted around the last molar of the corresponding arch then braided to the anterior mandible parallel to the gingival margin. This was completed bilaterally, so that 2 wires were present on each arch. The 2 wires were twisted together at the midline, producing an “arch bar.”
