INTRODUCTION
Orthognathic surgery involves the manipulation of facial bone architecture
through osteotomies to restore form and function, correcting malocclusion,
maxillomandibular disproportions, and facial asymmetries1. The repositioning of the jaws
takes place through the use of surgical guides made in the laboratory
(pre-operative) phase during surgical planning.
Virtual planning in orthognathic surgery is carried out with the help of software
that uses real measurements of the craniofacial skeleton and records of the
patient’s occlusion, through a 3D analysis, different from the 2D evaluation
of
conventional planning. It is possible to virtually simulate surgical movements
of the maxilla, mandible, and chin in all directions and create surgical guides
for 3D printing on the computer. Among the advantages, when compared to the
conventional method, are greater precision in the translation of the surgical
plan intraoperatively, in the creation of guides and a shorter time in executing
the planning2,3.
OBJECTIVE
The objective of this work is to demonstrate the use of virtual planning in a
series of 18 cases of patients with dentoskeletal deformities treated through
orthognathic surgery.
METHOD
Eighteen patients with dentofacial deformities were evaluated, according to
Angle’s classification (Class 1, 2, and 3), who underwent orthognathic surgery
using virtual planning between 2018 and 2019 at Hospital Felício Rocho - Belo
Horizonte-MG. The inclusion criteria were patients between 16 and 60 years old
with maxillomandibular disproportions, with or without asymmetries, in whom
orthodontic treatment alone was not sufficient to correct the malocclusion and
improve facial aesthetics. Exclusion criteria were the presence of cystic or
tumoral lesions in the jaws and clinical comorbidities that contraindicated the
surgical procedure.
Virtual planning was carried out on all patients, using Dolphin®
Imaging 11 software and surgical guides made with a 3D printer. In all cases,
multislice face or cone beam computed tomography scans, intraoral scanning of
the dental arches, and intraoral and extraoral photos were used to carry out
the
planning. The surgical guides were all made in resin using the same 3D printer.
The same surgeon carried out the virtual planning and execution of the
surgeries. The surgeries were performed under general anesthesia through
nasotracheal intubation.
The surgical technique used in the maxilla was Lefort I osteotomy; in the
mandible, sagittal osteotomies of the branches; and in genioplasty, basilar
osteotomy. All surgeries started with the maxilla, which, after mobilization,
was repositioned with the help of the intermediate guide created in virtual
planning and fixed with osteosynthesis materials (plates and 1.5 screws) in the
virtually planned position. Soon after, osteotomies of the mandible were
performed, repositioned in class 1 occlusion, and fixed with 2.0 osteosynthesis
material. A basilar osteotomy was performed to reposition the chin and fixed
with a 2.0 Paulus plate.
The follow-up time was a minimum of 6 months and a maximum of 14 months. The
degree of satisfaction of the aesthetic-functional result with the use of
virtual planning was evaluated using a numerical scale of 1-5 (1-completely
dissatisfied, 2-dissatisfied, 3-neither satisfied nor dissatisfied, 4-satisfied,
5-completely satisfied ). Profile teleradiography was performed 7 days
post-operatively to evaluate the maxillomandibular position.
RESULTS
The most common dentofacial anomaly was Class 2 (10 patients), followed by Class
3 (8 patients), with 3 patients in total presenting associated facial asymmetry.
Females were prevalent (10 cases). Ages ranged from 16 to 55 years old. The time
spent during virtual planning was 4 hours. Six patients underwent bimaxillary
surgery (maxilla and mandible), 11 patients underwent trimaxillary surgery
(maxilla, mandible, and chin), and 1 patient underwent monomaxillary surgery
(mandible/chin) associated with arthroplasty of the left temporomandibular joint
with a customized prosthesis.
The average hospitalization was 1 day. The average surgical time was 4 hours,
without any serious local postoperative complications such as recurrence of
malocclusion, pseudarthrosis, or infection in the 18 operated cases. A male
patient developed rhabdomyolysis without renal repercussions, with no diagnosed
etiology. The intermediate surgical guide presented perfect adaptation on the
occlusal surfaces, promoting great stability for repositioning and fixing the
maxilla in intermediate occlusion.
The 18 operated patients responded as “completely satisfied” in relation to the
aesthetic-functional result in this series studied. A very great similarity was
found between the position of the maxillofacial skeleton in the pre-operative
virtual planning and that obtained post-operatively through the evaluation of
cephalograms.
DISCUSSION
The historical development of orthognathic surgery dates back to 1906 when the
first surgery to correct mandibular prognathism was performed on a medical
student at the University of Washington by plastic surgery pioneer Vilray Blair.
The father of orthognathic surgery, Hugo Obwegeser, a European surgeon with
medical and dental training, introduced the technique of sagittal osteotomy of
the mandibular rami in 1950 and was also the pioneer in performing bimaxillary
surgery at the same surgical time. Bell, in 1975, in his work on the
vascularization of the maxilla, guaranteed the safety of complete mobilization
of Le Fort I osteotomies4.
In general, a pre-operative plan is the most important step in the workflow of
orthognathic procedures3.
Orthognathic surgery requires a precise assessment of complex dentofacial
deformities of the craniofacial skeleton. It is indicated for the correction
of
maxillomandibular disproportions with aesthetic and/or functional repercussions
(malocclusion, chewing, speech, or respiratory difficulties) in which isolated
orthodontic treatment is not sufficient.
The success of the surgical plan depends not only on the accuracy of the skeletal
and dental diagnosis of the deformity but also on the pre-surgical prediction
of
the proposed movements. It is the surgeon’s task first to define the original
position of the dentofacial skeleton and then estimate the desired final
position and, finally, develop a three-dimensional representation of the
movements necessary to achieve the intended objective1.
Previously, conventional surgical planning used manual cephalometric analysis of
lateral teleradiography, facial analysis, and sections of plaster models of the
patient’s dental arches. The plaster models were then repositioned in the
position determined by the surgeon, and surgical guides were manually created
with acrylic resin in the new position of the jaws.
However, the traditional approach has its limitations, especially in the case of
patients with major facial deformities or asymmetry, as 2D cephalometric images
cannot provide complete information about 3D structures. When conventional 2D
surgical plans are performed, unexpected problems may occur, such as a bone
collision in the ramus area, pitch discrepancy, plane spin rotation, midline
difference, and chin inadequacy5.
Advances in imaging methods such as cone beam tomography, multislice tomography
with reliable reproduction of craniofacial anatomy, and manual scanners with
a
recording of dental occlusion in high definition have enabled the virtual
execution of planning in orthognathic surgery, bringing a change in the
treatment paradigm of dentoskeletal deformities. Virtual planning in
orthognathic surgery is a process that integrates planning and surgical
intervention through the use of software that performs cephalometric analysis
in
three dimensions (3D) of the anatomy of bone tissue, occlusion, and soft tissue
(Figure 1).
Figure 1 - 3D assessment of the craniofacial skeleton, soft tissue, and
occlusion.
Figure 1 - 3D assessment of the craniofacial skeleton, soft tissue, and
occlusion.
The surgeon performs the virtual repositioning of the jaws (Figure 2) and creates surgical guides that will later be
printed on a 3D printer and used during the procedure1,2,6 (Figures 3 and 4).
Figure 2 - Simulation of maxillary, mandible, and chin movements during
virtual planning.
Figure 2 - Simulation of maxillary, mandible, and chin movements during
virtual planning.
Figure 3 - Use of the intermediate guide created during virtual planning in
the position defined by the surgeon with the maxilla fixed in the
new position. Lefort I osteotomy for maxillary advancement.
Figure 3 - Use of the intermediate guide created during virtual planning in
the position defined by the surgeon with the maxilla fixed in the
new position. Lefort I osteotomy for maxillary advancement.
Figure 4 - Mid-guide planning with virtual planning software. Source:
Personal collection.
Figure 4 - Mid-guide planning with virtual planning software. Source:
Personal collection.
Currently, the technological advancement of 3D printing technology and the
improvement of the elastic modulus of 3D printed surgical matrices have allowed
increasingly precise results5.
Applications of virtual planning in craniomaxillofacial surgery include
orthognathic surgery, TMJ prosthetic reconstruction, trauma, and oncologic
reconstruction, to name a few.
In orthognathic surgery, specifically, the advantages are increased accuracy in
the occlusal relationship, reduced surgery time, increased patient satisfaction,
reduced cost7,8, and reduced planning time by up to 30%9.
Furthermore, virtual planning allows for greater precision in predicting the
positioning of soft tissues in the sagittal plane, and patients treated with
it
present greater symmetry in the frontal view3. Pre-operative surgery simulation allows measurements of
up to one-hundredth of a millimeter, and when combined with 3D printed guides,
the functional and aesthetic result is superior to traditional two-dimensional
(2D) results. This reduced surgical time also directly translates into time
under anesthesia and reduced total cost6.
In 2012, research using patient satisfaction through a subjective assessment of
functional and aesthetic results showed that patients who underwent virtual
planning reported more favorable scores than those who underwent traditional
surgery7.
Virtual planning has challenged the current state of pre-operative preparation
and procedures in orthognathic surgery. Associated with medical prototyping of
3D printing, it has become a significant tool, demonstrating to be highly
accurate in terms of imaging, quantitative analysis, and predictability of
planned surgical movements. Virtually created surgical guides are reliable in
their construction and accuracy. Surgeons are reporting virtual surgery results
with margins of error within 2mm of predicted maxillary and mandibular positions
when comparing postoperative outcomes2,5 (Figure 5).
Figure 5 - Postoperative result of the patient. Vertical shortening of the
maxilla was performed with counterclockwise rotation of the plane
and advancement of the mandible and chin.
Figure 5 - Postoperative result of the patient. Vertical shortening of the
maxilla was performed with counterclockwise rotation of the plane
and advancement of the mandible and chin.
All these benefits can reduce planning time complications and surgical time
compared to conventional planning1,2,4,8,10. The next generation of
virtual planning will realize cutting guides for osteotomies and
three-dimensional printed osteosynthesis plates, corresponding almost
identically to the bone level in all planes of space8.
Future orthognathic surgical planning will undoubtedly be carried out by
three-dimensional virtual planning. Financial expenses, treatment planning time,
and intraoperative time will likely decrease due to the greater development of
three-dimensional virtual planning techniques11.
CONCLUSION
Virtual planning in craniomaxillofacial surgery, especially in orthognathic
surgery, is a tool that presents numerous advantages, such as reducing the time
of the pre-operative laboratory phase, greater precision in the creation of
surgical guides, and better reproducibility of simulated results.
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1. Hospital Felício Rocho, Belo Horizonte, MG,
Brazil
2. Faculdade Ciências Médicas de Minas Gerais,
Belo Horizonte, MG, Brazil
Corresponding author: Klaus Rodrigues Oliveira Rua
Fernandes Tourinho, 840, Savassi, Belo Horizonte, MG, Brazil, Zip Code:
30112-006, E-mail: contato@klausrodrigues.com.br
Article received: July 12, 2023.
Article accepted: August 20, 2023.
Conflicts of interest: none.
