Abstract
The author discusses a new role for stereolithic models in the management of complex mandibular fractures with reference to two case studies.
The use of stereolithic models has become more common as the technology becomes simpler and economically viable. Use of stereolithic models in oncology surgery, orthognathic surgery, implantology and temporomandibular joint (TMJ) arthroplasty is described in the literature, but little is published about their application in trauma.
Complex maxillofacial trauma is challenging to manage due to the extent of injury and distortion of anatomy. Establishment of a stable occlusion forms the basis for restoration of the facial anatomy. Experience in using stereolithic models for planning in major reconstructive surgery in the author’s department has led to adaptation of their use in trauma.
In acute and secondary trauma settings, possible uses of stereolithic models are for: pre-bent cranioplasty plates ; custom made orbital plates (direct and mirror imaged); preoperative surgical planning ; preformed plates; custom arch bars; and teaching and training. In the author’s department, Dicom data from computed tomography (CT) scans are used to enable the rapid construction of stereolithic models. In cases of complex mandible fractures, this allows accurate preoperative planning and model surgery.
An Objet 30 three dimensional (3D) printer is used to print the model. A full face model can be prepared within 16 h at a cost of approximately £100. This machine allows for an accurate level of stereolithic model construction (28 micron build layer). The model is accurate enough to reconstruct a displaced occlusion without the need to scan plaster models. Two cases demonstrating the advantage of stereolithic models are described below.
Case 1
A 39-year-old female attempted suicide by jumping off a motorway overpass. Her injuries included multiple long limb fractures and grossly comminuted fracture of the anterior maxilla. The maxillary fracture involved displacement of the fracture fragments ( Fig. 1 ). Data from the CT scan was used to construct a stereolithic model. The fracture was reduced on the model, allowing construction of custom made arch bars. The arch bars were secured under general anaesthetic and the patient secured in intermaxillary fixation (IMF) for 6 weeks. On release of IMF her end occlusion was stable and reduced, with good clinical and radiographic signs of fracture healing.
Case 2
A 19-year-old female fell from a 6 foot wall. During the fall, her chin struck the edge of the wall. She sustained significant mandibular fractures, impaction of her hemi-maxilla with mid-palatal split, and multiple complex enamel dentine fractures. She attended the accident and emergency department and underwent a CT scan ( Fig. 2 ). Dicom data were used to create a stereolithic model, which was used to reduce the patient’s fractures ( Fig. 3 ) in the laboratory. This allowed construction of custom made arch bars and a pre-bent osteosynthesis plate for the anterior maxilla. The patient received definitive surgery within 48 h of injury.
