Abstract
Introduction
The utility of CAD/CAM technology in the treatment of mandibular defects has been demonstrated, allowing effective analysis, diagnosis and treatment for bone defects, however the high cost and sometimes the difficult access to this technology limits its use.
Materials and methods: observational descriptive cross-sectional study in which craniofacial bone defects were analyzed with emphasis at the mandibular level, with free 3D reconstruction software, determining characteristics of the population and bone defect. A management workflow is proposed and some cases analyzed are presented.
Results
50 patients with craniofacial bone defects were collected over a one year period. Mandibular defects account for 44% of the total sample, the majority of cases involving more than one mandibular area; the most affected areas were the body and parasymphysis; the average bone defect size was 36mmx56 mm × 15 mm. The proposed low cost workflow allows multidisciplinary work with industrial design teams to ensure the best treatment for the patient.
Conclusions
It is possible to implement low-cost management of mandibular defects. The multidisciplinary work between reconstructive surgeons, industrial design and biomedical engineering is useful for the treatment of patients.
Highlights
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Mandibular defects represents an impairment in functional and appearance aspects, both need to be recovered.
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Mandibular Reconstruction is challenging and requires experience and knowledge on advanced reconstructive techniques and available technologies.
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Knowing the defect characteristics is the first step in the reconstructive sequence and is possible to do it in a safest and accurate way by using 3d reconstruction.
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Low cost reconstruction workflows may be an option of equal quality and precision in mandibular defects.
1
Introduction
Technologies such as 3D printing, reverse engineering, virtual surgical planning and computer-assisted surgery have a great impact on multiple branches of medicine [ , ]. Mandibular defects, are frequent reasons for consultation and is important to know their etiology and severity for accurate diagnosis and treatment [ ]. The use of medical images, allows us to analyze compromised bone components, this together with the implementation of CAD/CAM (Computer-Aided Design/Manufacturing) technology facilitates the planning and optimization of a precise and personalized surgical treatment based on virtually reconstructed models [ ]. The current trend is to perform treatments using objective methods that allow measurement and evaluation of error, which is why the research in the area of applicability and implementation of engineering and computation in analysis, preoperative planning and patient treatment are of great importance and significance .
Having access to this type of technology represents a high cost and need for training of surgeons, in addition, there are no studies that characterize the population of patients with mandibular bone defects of variable etiology; the available studies characterize maxillofacial trauma but do not describe the characteristics of bone defects and their treatments [ ].
The objective of this study is to show the diagnosis and management of mandibular bone defects with application of low-cost CAD/CAM technology.
2
Materials and methods
This is a descriptive, observational, prospective study, carried out jointly by the programs of Plastic Surgery and Industrial Design of the Industrial University of Santander, at the University Hospital of Santander. Patients treated between January and December 2017, diagnosed with complex craniofacial bone defects were identified, those patients with mandibular defects were chosen for study. ( Table 1 . Inclusion and exclusion criteria).
| Inclusion criteria | Exclusion criteria |
|---|---|
| ✓Patients with mandibular bone defects, followed by departments: neurosurgery, maxillofacial surgery, otolaryngology, head and neck surgery and plastic surgery. ✓Complex mandible fractures (more than 3 fracture lines, comminuted fractures, panfacial, severe displacement, avulsion, bone lost). ✓Complex oncological mandible defects (neoplasm, resection). ✓Complex congenital mandible defects |
✓CT scans that do not comply with the institutional protocol: axial, coronal and sagittal cuts of less than 1 mm. ✓Patients who received treatment at another institution. |
CT (Computed Tomography) were analyzed with free three-dimensional design and reconstruction software, performing the characterization of the bone defect, surgical planning and design of useful instruments for the treatment of each patient; an institutional workflow for the treatment of patients with complex mandibular defects was designed previously . ( Fig. 1 ) ( Table 2 . Variables evaluated). Statistical analysis was performed with Stata 12.0.
| Variable | Description |
|---|---|
| Age | Years of life |
| Gender | Male, female |
| Defect etiology | Determine if the defect is due to trauma, oncological pathology or congenital malformation |
| Mandibular defect site | Mandibular region compromised by the defect: Symphysis, parasymphysis, body, angle, branch, condyle. |
| Diagnosis | Diagnosis at institutional admission |
| Chronology | Classification of bone defect according totimeline: acute (less than 15 days), subacute (15 days–3 months) or chronic (more than 3 months) |
| Previous reconstructive surgery | History of previous surgery |
| Procedure received | Type of procedure received |
| Treating specialty | Specialty on charge of the patient (Plastic Surgery, Maxillofacial surgery, Head and Neck surgery, Neurosurgery, otolaryngology) |
| Solicited service | Service indicated for treatment of bone defect: •Virtual Surgical Planning •Measurement and verification •Biomodel printing •Implant design •Guides (cutting, bite, position) design •Molds for grafting |
| Variables evaluating bone defect | Description |
| Height | Measurement of the defect from head to foot |
| Width | Horizontal measurement of the defect, from side to side |
| Thickness | Distance between front and back surfaces of the defect |
| Bone mineral density | Bone mineral density of the bones compromised by the defect, (NORMAL VALUES: 0.97 – 1.28 g/cm 2 ) |
| Modulus of elasticity | Measure of the stress–strain relationship, important parameter in the evaluation of the deformation response of concrete under working loads |
All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional research committee: Ethics committee in scientific research of the Universidad Industrial de Santander, (CEINCI-UIS), N° 1. And with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
3
Results
A sample of 50 patients with complex craniofacial bone defects was obtained, of which 22 patients (44%) had bone defects that compromised the mandible, being this the most compromised bone in the population. The most affected area was the mandibular body followed by the parasymphysis and symphysis. The majority of patients had more than one compromised mandibular area. More than 50% of the population with mandibular bone defects were male and older than 40 years, and the most common etiology was neoplasm, with 45%, followed by congenital malformations (32%), with a chronic evolution time (in 91% of the cases). Among patients with previous reconstructive treatment, the most frequently performed procedure was bone resection and reconstruction with free flap or bone graft ( Table 3 ).
| Variable | Number of cases (n) | Percentage% | |
|---|---|---|---|
| Age (yr) | <20 | 4 | 18 |
| 20–40 | 3 | 14 | |
| 41–60 | 9 | 41 | |
| >60 | 6 | 27 | |
| Gender | Female | 8 | 36 |
| Male | 14 | 64 | |
| Defect etiology | Congenital | 7 | 32 |
| Traumatic | 5 | 23 | |
| Oncological | 10 | 45 | |
| Mandibular defect site | Symphysis | 14 | 64 |
| Parasymphysis | 16 | 73 | |
| Body | 18 | 82 | |
| Angle | 10 | 45 | |
| Branch | 4 | 18 | |
| Condyle | 4 | 18 | |
| Diagnosis | sequels of CLP | 1 | 5 |
| Mandibular prognathism | 2 | 9 | |
| Mandibular retrognathism | 2 | 9 | |
| Other congenital malformations a | 4 | 18 | |
| Fractures | 3 | 14 | |
| Secuelas of fracture | 2 | 9 | |
| Traffic accidents | 2 | 9 | |
| Gunshot wound | 3 | 14 | |
| Temporomandibular Joint | 1 | 5 | |
| Bening bone tumor | 1 | 5 | |
| Malign skin tumor, compromising adjacent bone | 4 | 18 | |
| Malign bone tumor | 5 | 23 | |
| Chronology b | Acute | 1 | 5 |
| Subacute | 1 | 5 | |
| Chronic | 20 | 91 | |
| Previous reconstructive surgery | Yes | 6 | 27 |
| No | 16 | 73 | |
| Procedure received | Fractures Reduction and fixation | 1 | 5 |
| Bone resection + free flap reconstruction | 2 | 9 | |
| Bone resection + bone graft | 2 | 9 | |
| Bone resection + bone graft + local flap | 1 | 5 | |
| Treating specialty | Plastic surgery | 5 | 23 |
| Maxillofacial surgery | 5 | 23 | |
| Head and neck surgery | 5 | 23 | |
| Plastic surgery & maxilofacial surgery | 3 | 14 | |
| Plastic surgery & neurosurgery | 1 | 5 | |
| Plastic surgery & head and neck surgery | 3 | 14 | |
| Solicited service | Virtual Surgical Planning | 22 | 100 |
| Measurement and verification | 2 | 9 | |
| Biomodel printing | 21 | 95 | |
| Implant Design | 3 | 14 | |
| Guides (cutting, bite, position) design | 18 | 82 | |
| Molds for grafting | 3 | 14 | |
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