The surgical management of facial fractures by Oral and Maxillofacial Surgeons is commonly open reduction internal fixation (ORIF) and intermaxillary fixation (IMF). IMF has been a well-documented method of management of mandible fractures for many years [ ] and is often achieved via custom made arch bars. The traditional method for constructing arch bars is to take alginate impressions, cast these to produce study models and then adapt them around the casts. We highlight the use of a novel technique to produce arch bars from Computed Tomography (CT) scans, therefore rendering alginate impressions obsolete.
The majority of maxillofacial trauma patients will present through the Emergency Department and as part of their initial assessment and investigations will undergo a CT imaging. A 3-Dimensional (3D) reconstruction of a CT scan is invaluable in major facial trauma as it allows complete visualisation of fracture lines, extent of displacement and relation to anatomical structures [ ].
The authors demonstrate two patients who sustained extensive mandibular and maxillary fractures, requiring surgical intervention. With the use of computer-aided design software ‘Materialise: Mimics in Print’, the images from the patients CT scan are used to print 3D models in VeroDent Plus MED690 (acrylic-like dental resin), which was then used to construct the arch bars against in the traditional manner ( Fig. 1 ). The level of detail able to be produced during a reconstruction of a CT scan is demonstrated in Fig. 2 .
Table 1 compares the approximate timings and costings of traditional versus digital construction of arch bars. Although the digital time appears longer (285 vs 205 min), printing the 3D model does not physically take up the technician’s time, as this is the time taken in the printer. Therefore, there is an overall 70-min reduction in man-hours versus the traditional method (n = 135 min). There is also a reduction in cost per case by £13.44 using the digital vs traditional method.
| Costings | Digital | Physical | |
|---|---|---|---|
| Technical Time | 135 min/£31.50 | 185 min/£43.11 | |
| Model Resin | £7.36 | N/A | |
| Alginate, stock spray, adhesive, stone | N/A | £1.09 | |
| Clinical Time | N/A | 20 min/£8.10 | |
| Total | £38.86 | £52.30 | |
| Production Time | |||
| Segmenting Model from CT | 20 min | Disinfection | 20 min |
| Preparing Model for Printing | 10 min | Cast in Stone | 60 min |
| Printing Model | 150 min | Trim | 5 min |
| Post Processing/Cleaning | Automated (Technician Agitation Time: 2mins) | Dry | 30 min |
| Bending Arch Bars | 90 min | Bending Arch Bars | 90 min |
| Total | 2272 min (4.53 h) | 205 min (3.42 h) | |
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