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Case Report
DOI: 10.17354/cr/2015/105
A Systematic Approach for Splint Fabrication in
Orthognathic Surgery: Case Series
Shashank Uniyal1, Somil Chhag2, S Anilkumar3, N Jayakumar4, Marut Patel5
Senior Lecturer, Department of Prosthodontics, Government Dental College, Kottayam, Kerala, India, 2Senior Lecturer, Department of Oral and
Maxillofacial Surgery, Government Dental College, Kottayam, Kerala, India, 3Professor and Head, Department of Prosthodontics, Government Dental
College, Kottayam, Kerala, India, 4Associate Professor, Department of Oral and Maxillofacial Surgery, Government Dental College, Kottayam, Kerala,
India, 5Post-graduate Student, Department of Prosthodontics, Government Dental College, Kottayam, Kerala, India
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Orthognathic surgery involves the surgical manipulation of the facial skeleton to correct anatomical and functional deformities. Model
surgery is an integral part of orthognathic surgery. It gives the three-dimensional understanding of the post-operative relationship of the jaws.
Orthognathic model surgery has been used to assist the surgeon in repositioning the upper and lower jaws into a predicted position. Model
surgery planning has generally been carried out using one of two techniques - The lock wood key spacer technique or Eastman Dental Hospital
anatomically orientated model surgery technique. This work presents our experiences in model surgery using modified Eastman’s technique.
Keywords: Articulators, Occlusal splint, Orthognathic surgery
INTRODUCTION
Dentofacial deformity is a condition primarily affecting
jaw and dentition. Problems associated with dentofacial
deformity include the inability to incise or chew, speech
impairment, unacceptable esthetics, temporomandibular
joint disorders, and psychological issues. There are two
modalities for the correction of dentofacial deformities,
i.e., orthodontic treatment and orthognathic surgery.
Orthodontic treatment offers limited scope in severe
dentofacial deformity. Orthognathic surgery attempts
to establish normal esthetic and functional anatomy for
patients suffering from dentofacial disharmony. It is the
task of the surgeon to first define the original position of the
dentofacial skeleton, and then to estimate the desired final
position, and finally to develop a three-dimensional (3D)
representation of the movements necessary to accomplish
the intended goal.1
The planned surgical procedure is performed on a plaster
cast of the patient’s jaws and teeth. Splints thus fabricated
after model surgery are used as a surgical guide for
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repositioning maxillary and/or mandibular osteotomized
segments.2,3 Recent advancement in the field of orthognathic
surgery is the use of computer-aided design/computer-aided
manufacturing (CAD/CAM) in development of surgical
planning for the treatment of complex craniomaxillofacial
deformities.4-9
Model surgery is a pre-surgical laboratory procedure done
on anatomically mounted jaw models to ensure that the
jaws have been positioned into the prescribed relationship.
Steps in model surgery:
1. Impression making
2. Model preparation
3. Facebow transfer
4. Articulation and model surgery
5. Splint fabrication.
CASE REPORTS
Case Report 1
A 23-year-old female reported with the complaint of upper
teeth being too much visible and large lower jaw. Based
on various facial and radiographic measurements the
treatment plan proposed was Le-fort I superior impaction
(for correction of increased upper facial height) and bilateral
sagittal split osteotomy (BSSO), set back (for correction of
mandibular prognathism). After completion of 4 months
of pre-surgical orthodontic treatment phase model surgery
was performed.
Corresponding Author:
Dr. Shashank Uniyal, Department of Prosthodontics, Government Dental College, Kottayam, Gandhinagar - 686 008, Kerala, India. Phone: +917736364073. E-mail: [email protected]
IJSS Case Reports & Reviews | July 2015 | Vol 2 | Issue 2
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Uniyal, et al.: Splints in Orthognathic Surgery
Impression Making
Two sets of irreversible hydrocolloid (Neocolloid, Zhermack)
impression were made. One was kept to analyze and
document the pre-operative situation, and other was used
to perform mock surgery.10 Orthodontic brackets were
blocked out with wax to prevent tearing and distortion of
the impression during removal.
Model Preparation
Impressions were poured with Type IV dental stone
(Kalrock, Kalabhai). Precaution was taken to avoid bubbles/
voids in pour-up because it may lead to an inaccurate fit
of intra-operative occlusal splints due to altered occlusal
relationship, particularly with segmental procedures.
FaceBow Transfer
The models were oriented in a semi-adjustable Hanau H2
articulator after facebow transfer (Figure 1). A facebow
transfer is essential because significant differences between
planned and surgical jaw movements can result from
the difference between the true and simulated centers of
mandibular rotation, as well as from the erroneous transfer
of reference lines and points, between model surgery and
operation.11
Articulation and Model Surgery
The mandibular cast is mounted on the articulator using
a centric wax record. Reference lines were drawn in order
to make all movements visible in a three dimension.10
Horizontal reference line drawn at 10 mm and 20 mm
from the articulating ring and parallel to the occlusal plane
(Figure 2). The upper assembly is removed. The cast is
segmentalized with a sharp saw and moved to reproduce
the movement prescribed by the surgeon (10 mm of superior
impaction). The maxilla is repositioned 10 mm upward in
accordance with vertical reference lines. The segmented
parts are sealed together using sticky wax (Figure 3).
Fabrication of Splints
Used intra-operatively to position a mobile osteotomized
jaw against the other stable jaw. If a single jaw is being
repositioned, one surgical splint is used to guide the
occlusion of the jaw, or a segment being moved relative to
the remaining jaw and is then wired or screwed in place. If
both maxillary and mandibular repositioning osteotomies
are planned, two surgical splints are made. A primary
or intermediate splint is used to guide the movement of
one jaw relative to the other jaw. Then, the secondary or
final surgical splint is used to reposition the remaining
jaw. Splints were fabricated with auto polymerizing resin
(Rapid Repair, Pyrex) and color coded to avoid confusion.
The upper and lower cast were coated with a layer of
separating medium (cold mold seal, pyrex) and allowed to
dry. A combination of salt and pepper and dough method
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was used.12 The occlusal surface wetted with monomer and
sprinkled with a thin layer of polymer onto the monomer.
Acrylic is rolled into a cylindrical shape at dough stage,
adapted to the lower teeth, and the upper cast is rotated
into occlusion. Excess acrylic is trimmed with scissors
and left for curing (Figure 4). Undercuts and the buccal
surfaces trimmed to permit visual verifications of proper
seating at the time of surgery. All the external surfaces were
sandpapered, pumiced, and polished.
The mandibular cast was dearticulated and again
rearticulated by moving 5 mm backward at a stable
occlusion (to mimic BSSO set back), final splint fabricated
in this position by the same method (Figure 5). These splints
are used during surgery for repositioning of osteotomized
segments of the jaw (Figures 6-8).
Figure 1: Facebow transfer
Figure 2: Vertical and horizontal reference lines: Lateral view and frontal view
Figure 3: Segmented parts sealed together using sticky wax: Lateral view and
frontal view
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Uniyal, et al.: Splints in Orthognathic Surgery
Figure 4: Intermediate splint
Figure 5: Final splint
Figure 7: Semi-rigid fixation by mini plate
Figure 8: Set back guided by final splint
fracture line (backward positioning of anterior maxilla).
After completion of 4 months of pre-surgical orthodontic
treatment phase model surgery was performed.
Figure 6: Superior maxillary impaction guided by intermediate splint
Case Report 2
A 22-year-old female reported with a chief complaint of
upper front teeth placed too forward. Based on various
facial and radiographic measurements, the treatment
plan proposed was Le-Fort I superior impaction and
anterior maxillary osteotomy (AMO) based on Le-Fort I
IJSS Case Reports & Reviews | July 2015 | Vol 2 | Issue 2
Two sets of impression were made and cast poured, out
of which one set was mounted on semi-adjustable Hanau
Wide Vue articulator using a facebow record. Horizontal
reference line marked on maxillary cast 10 mm from the
articulating ring and vertical lines marked in canine, second
premolar and first molar region (Figure 9). A customized
incisal pin was fabricated to calculate the amount of setback achieved (Figure 10). AMO fracture line marked, and
model segmentalized with a sharp saw along the line. First
premolars of both sides were removed along a “V” shape
cut. The remaining segment fused with sticky wax and
articulated back with the help of reference lines (Figure 11).
Repositioning splint is made in this position and used to
reposition osteotomized maxilla with the stable mandible.
Case Report 3
A 28-year-old male reported with a chief complaint of tilted
upper half of face (Figure 12). Based on various facial and
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Uniyal, et al.: Splints in Orthognathic Surgery
radiographic measurements, the treatment plan proposed
was Le-Fort I superior impaction with correction of right
side canting. Two sets of impression were made, and
cast poured, out of which one set was mounted on semiadjustable Hanau H2 articulator using a facebow record.
Asymmetrical horizontal cutting was required in maxilla
to compensate for canting in the occlusal plane. Selective
superior repositioning of 7 mm on right side and 2 mm on
left side is performed to achieve a horizontal occlusal plane
Figure 9: Vertical and horizontal reference lines
(Figure 13). Segments were rearticulated and repositioning
splint fabricated with auto polymerizing resin in this
position (Figure 14). This splint is used to reposition the
osteotomized maxilla with respect to mandible during
surgery.
DISCUSSION
Planning orthognathic model surgery on semi-adjustable
articulator offers various advantages. The significant
anteroposterior error inherent in the simple hinge articulator
creates inaccurate interocclusal splints and should therefore
not be used for this purpose. Canted occlusal planes and
edentulous spaces require full 3D control during planning
and surgery, hence there is a need for a facebow and semiadjustable articulator with models oriented to the Frankfort
plane or true postural horizontal plane.13 Semi-adjustable
articulator with its arbitrary facebow can even reproduce
an anesthetized patient’s hinge axis movements.14
Modern technologies including navigation surgery have
been used in orthognathic surgery to increase the precision
of surgical movements of bone segments. The virtual
orthognathic 3D planning software is an excellent tool,
which assists in diagnosis, planning of virtual treatment,
and post-operative evaluation of craniomaxillofacial
deformities. However, the surgical transfer of virtual
surgical plans remain unpredictable.15 Various approaches
that use internal and external references and positioning
devices have been attempted, but could not be established
in practice. Orthognathic surgical planning therefore still
relies on the use of maxillomandibular-interocclusal splints,
which are required to position the maxilla or mandible.16
CONCLUSION
Figure 10: Customized incisal pin
In this modern era of evidence-based dentistry, presurgical planning is essential for the predictable result of
orthognathic surgery. A systematically performed model
surgery aids the oral and maxillofacial surgeon to decide
the exact surgical movement necessary to obtain desired
occlusion and esthetics. Latest computerized, and rapid
Figure 11: Anterior maxillary osteotomy fracture line marked, model segmented, reapproximated and sealed
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Uniyal, et al.: Splints in Orthognathic Surgery
REFERENCES
Figure 12: Frontal view showing occlusal canting
Figure 13: Selective superior repositioning through selective trimming: Anterior
view and posterior view
Figure 14: Reapproximated and sealed model
prototyping technologies let us fully imagine, design, and
control orthognathic procedures without information loss
among the surgeons, orthodontists, and prosthodontist.
With the use of these modern techniques error sources
inherent in conventional model, surgery procedures may
be eliminated. Still, a major paradigm shift from routine
planning to 3D virtual planning will take time till these
techniques become easily accessible, user-friendly, and
available at relatively low cost.
IJSS Case Reports & Reviews | July 2015 | Vol 2 | Issue 2
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How to cite this article: Uniyal S, Chhag S, Anilkumar S, Jayakumar N,
Patel M. A Systematic Approach for Splint Fabrication in Orthognathic Surgery:
Case Series. IJSS Case Reports & Reviews 2015;2(2):5-9.
Source of Support: Nil, Conflict of Interest: None declared.
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