Before the discovery of the biocompatibility of titanium spearheaded by Branemark in the early 1980s, open plating techniques to address mandible fractures were fraught with complications. Techniques for fracture fixation usually consisted of intermaxillary fixation (IMF) for prolonged periods of time, usually 6 weeks. Erich arch bars and Ivy loops were in common use as was the use of oral splints and circummandibular wires and suspension wires when midface fractures were present. Alloy plates were adapted from orthopedic surgery for mandibular fixation, but the compound nature of mandible fractures, which are frequently open to the oral cavity with its aerobic and anaerobic flora, created a milieu that favored infection. Nevertheless, engineering principles were developed by many different investigators often in partnership with industry to define the optimal reconstruction method to counteract the massive forces of mastication under which the mandible routinely operates.

The Arbeitsgemeinschaft für Osteosynthesefragen/Association for the Study of Internal Fixation (AO/ASIF) was in the forefront of defining the precise characteristics of plates and screws that are required for open reduction and internal fixation (ORIF) of fractures. The ultimate benefit of engineering a repair properly was the opportunity for immediate function directly after surgery. Without immediate function, patients had their jaws wired shut with subsequent interference with nutrition and substantial weight loss. Compliance with IMF was dismal, especially considering that many patients with mandible fractures had a history of substance abuse. Oral hygiene is challenging when patients are in IMF and dental and periodontal health suffered when closed techniques were used. Finally, temporomandibular joint fixation, especially in the presence of condyle fractures, was a major, though probably under reported, complication of prolonged IMF.

Titanium changed what could be achieved with open techniques. Plates and screws were less likely to become infected or rejected. In fact, bone would encapsulate the screws and the plates over time. Now, surgeons could confidently place titanium implants, and if they adhered to the engineering principles properly, the likelihood of successful ORIF of fractures became an expected rather than an unusual event. New techniques were developed including transoral and endoscopic approaches to the mandible. Instrumentation was developed to support these techniques.

The titanium implants at this time were designed to compress bone fragments as compression was thought to promote beneficial primary bone healing, which obviated the need to develop a callous and progress through secondary bone healing. The plates had countersunk holes and chamfered screw heads to take advantage of the spherical gliding principle whereby the screw head levered the bone fragments into compression when the screw was tightened. This compression could be oriented in several directions depending on the design and orientation of the countersunk hole in the plate. Because the mandible has a nerve running through the center (the inferior alveolar nerve), plates could not be placed in the optimal engineering position, which is right down the center of the jaw. This is partly because in order to gain the compression force generated by the screw, the screw must pass through both the lingual and the buccal cortex (bicortical screw). The need to place a bicortical screw meant that the screw could not be placed in a position where there was the risk of penetrating the neural
canal and piercing the nerve. This would risk permanent numbness of the lip from injury to the mental nerve. Therefore, the plate had to be placed on the inferior border of the mandible. However, when the plate is placed on the inferior border of the mandible, it must be either long or thick or both to overcome the tensile forces of mastication generated by chewing. Otherwise, every time chewing occurred, there would be a tensile-type gap occurring at the occlusal surface of the fracture, and this would be detrimental to bone healing.

The concept of the tension band was developed where some sort of fixation was necessary at the upper border of the fracture to counteract this tensile force. Tension bands either consisted of wiring teeth together, usually with an Erich arch bar, or in edentulous areas by placing a four-hole monocortical miniplate to counteract the forces of mandibular function. As a rule of thumb, a six-hole bicortical plate alone on the inferior border was thought to have enough strength to counteract occlusal surface tensile forces. An acceptable alternate approach was to use a four-hole inferior border bicortical plate with an occlusal surface tension band—either an arch bar in dentate areas of the jaw or a four-hole monocortical miniplate. These techniques as outlined were designed to be absolutely rigid and to bear the entire load of mastication. They are therefore referred to as load-bearing fixation techniques. Throughout the United States and much of Europe, this load-bearing technique was considered the standard approach to ORIF of mandible fractures, which had the major benefit of allowing the patient to progress to immediate function directly after surgery.

The above-described “AO standard” technique worked well in the hands of many surgeons for many years. However, the design of the technique was based upon using bicortical screws to obtain enough purchase to compress the fracture to obtain primary bone healing. How vitally important is it to have primary bone healing? If primary bone healing through compression is not needed, might one use monocortical rather than bicortical screws? If monocortical screws are used, can the plate be placed in a more optimal location to counteract tensile force at the occlusal surface of the mandible without the risk of impaling the inferior alveolar nerve? Also, are there situations where compression is not desirable? For instance, in a fracture of the angle of the mandible, the surface area of the bone is narrow in cross section, and fractures, while common, are often oblique. Compression of an oblique fracture could actually distract the fracture creating malocclusion. Michelet and Champy asked these questions and found a different answer than what was being practiced by many maxillofacial trauma surgeons.

Maxime Champy reported the results of stress shielding studies in Araldite models that examined the stress and strain characteristics at play in mandible fractures. What he found was that the tensile force at the angle of the mandible amounted to about 60 decanewtons (daN) and that the tensile force at the mandible anterior to the mental foramen was about 100 daN. A six-hole monocortical miniplate with 6-mm screws just penetrating the buccal cortex could overcome the 60 daN force if placed in an optimal location on the superior border of the mandible. In anterior locations, given the greater amount of force at play and the fact that twist and torsion is more possible, Champy recommended placing two monocortical miniplates in an optimal location derived from the force studies on the Araldite models. Champy also placed the plates via a transoral incision because placement of these small plates did not require as much exposure as placing large bicortical plates and screws. Although originally a short period of IMF was used (7 to 10 days) because the fixation technique is not absolutely rigid, subsequent clinical case series have shown that supplemental IMF is not required when using Champy’s technique. Because the Champy technique is not rigid enough to prevent small amounts of movement and because it counteracts tensile forces at the fracture site without addressing compressive forces, it is referred to as a load-sharing nonrigid technique. In short, Champy simplified the ORIF technique of mandible fractures by using miniplates, which did not use the compression which necessitated bicortical screws. This allowed placement of the plates in a more optimal engineered position to counteract the forces of tension at play in a mandible fracture without placing the inferior alveolar nerve at risk. Champy’s engineering concept resulted in “Champy’s lines of osteosynthesis,” which is in effect a blue print for optimal monocortical plate placement to address mandible fractures (Fig. 48.1). However, primary bone healing was lost in the process
in favor of secondary bone healing through callous formation. Subsequent case series have shown Champy’s technique to be the most complication-free technique in the literature. Nevertheless, as a minimalist engineering technique of repair, the Champy technique is unforgiving if attention to detail is not maintained.

Patients with mandible fractures typically present acutely, however, occasionally underlying substance abuse or psychiatric or other factors delay presentation. Patients with mandible fractures may be part of a multiple trauma event and like any patient with multiple trauma should be treated as dictated by good ATLS (advanced trauma life support) practice including assessing the ABCs (airway, breathing, circulation) and clearing the cervical spine. Sometimes patients will relate an accident linked to biking or to other types of sports. Other times, the patient will have had an altercation resulting in interpersonal trauma that results in a fracture. Spousal abuse should be investigated as part of the history of a mandible fracture as protective services may be necessary in cases of battery. Historical information related to previous dental history is sometimes helpful, such as information relating to partial or complete dentures or a history of crown and bridge work or titanium implants. Nevertheless, restorations will usually be apparent after imaging studies are obtained. A thorough social history concentrating upon substance use is important as patients who are alcoholics may be at risk for withdrawal and delirium tremors while undergoing care, and this circumstance can be life threatening. Likewise, the use of heroin, methamphetamines, and cocaine should be elicited to help prevent withdrawal or other problems related to substance abuse. A history of psychiatric intervention is important as continuity of treatment and compliance with medication regimens is important in the postinjury period. The patient should be asked if loss of consciousness occurred either before or after the trauma event as this may impact the type of imaging sought and have importance for calling upon other specialties for consultation. Medical comorbidities, past surgical history, and the presence or absence of drug-related allergies are also important to include in the initial assessment.