Over jet 5 mm or more or a zero to negative value (normal 0–2 mm).

Molar relationship discrepancy of 4 mm or more (normal is 0–1 mm).

Skeletal facial deformity of two or more standard deviations from published norms.

Open bite: no vertical overlap of the anterior teeth or posterior open bite of 2 mm or more.

Deep overbite with irritation of tissues.

Supraeruption of dentoalveolar segment due to lack of occlusion.

Presence of skeletal transverse discrepancy of two or more standard deviations from published norms.

Maxillary palatal cusp to mandibular fossa relationship that is 3 mm or greater for a unilateral or 4 mm or greater for a bilateral relationship. Of note, one must differentiate between dental tipping and skeletal deficiencies in this deformation.

3 mm or greater of asymmetry in any vector with 3 mm associated occlusal asymmetry.

Patients with severe class II and class III problems, anterior open bite, markedly increased overbite, and facial asymmetries.

Once the skeleton and dentition are aligned, the surgery may lead to improved speech, esthetics, function, and social interactions, and alleviate temporomandibular joint dysfunction.

Cleft lip and palate patients with maxillomandibular skeletal disharmony.

Facial syndromes and congenital anomalies.

Dental compensation is nature’s attempt to camouflage a jaw deformity.

Orthodontic decompensation aims to reverse the natural compensation of teeth and move them into their appropriate axial inclination within the upper or lower jaw so they are housed within the alveolus.

Remember that the upper and lower incisor angulations drive the anterior- posterior position of the maxilla and mandible into their final position.

The orthodontic decompensation will exaggerate the malocclusion and thus make the skeletal deformity more noticeable.

In class II skeletal patients, the retroclined upper incisors should be aligned over the alveolar bases (proclined to 102 degrees to SN) to maximize the overjet while at the same time maintaining a normal angulation. Caution must be used so that the transverse position of the maxillary canines does not block out the mandibular incisors as the mandible is advanced surgically. The lower incisors are typically proclined in this population and the goal should be to have the lower incisors at 90–95 degrees to the mandibular plane. This may require removal of the first or second bicuspids or reproximation (stripping) if very significant crowding exists.

In class III skeletal patients, the lower incisors are usually found to be retroclined and upper incisors proclined. The lower incisor dentition in these patients should be proclined so that the lower incisor is at 90–95 degrees to the mandibular plane. The upper incisors should be retracted to obtain and angle near 102 degrees to SN.

All teeth are aligned when gross crowding, spaces, or rotations are corrected.

Adjustments for tooth size discrepancy (TSD) – calculated with Bolton’s analysis (see below).

Lingual cusps of the mandibular posterior teeth should be 1 mm below the buccal cusps.

Palatal cusps of the maxillary posterior teeth should be 1 mm below the buccal cusps. Plunger cusps create open bites post-op as the dentition relapses.

Bolton Analysis

Determines the disproportion of the size of the permanent maxillary and mandibular teeth (tooth size discrepancy between the upper and lower teeth). Two ratios are calculated (overall ratio and anterior ratio).

The overall ratio is calculated by taking the sum of the mesiodistal width 12 mandibular teeth (first molar to first molar) divided by the sum of the mesiodistal width of the 12 maxillary teeth. According to Bolton, the overall ratio should be 91.3%. A ratio less than 91.3% indicates maxillary tooth excess.

The anterior ratio is calculated by the sum of the mesiodistal widths of the anterior mandibular teeth divided by the sum of the mesiodistal widths of the anterior maxillary teeth (canine). According to Bolton, the overall ratio should be 77.2%. A ratio less than 77.2% indicates maxillary tooth excess.

Tables are available in multiple orthodontic textbooks with calculated ratios easily obtainable.

Teeth may not interfere with planned skeletal movement.

Both dental arches should be reasonably compatible with one another at the time of surgery to allow maximum intercuspation post-surgically.

Arch form must be changed to expand the constricted areas in the more tapered arch or change narrow arches into more rounded form.

As a general rule, orthodontic expansion should be limited to 4–5 mm total, although this depends on angulation of the posterior teeth. In many cases, there is dental compensation (vertical position of maxillary posterior teeth) that can easily be corrected with orthodontic treatment up to 6–7 mm. However, if the position of the posterior teeth is angulated facially with narrow basal bone surgical expansion is indicated.

For severe maxillary transverse discrepancy surgical correction greater than 5 mm, surgically assisted rapid palatal expansion (SARPE) or segmental osteotomy should be considered.

At the conclusion of presurgical orthodontic goals, the patient should be in full dimension rectangular steel arch wire that fills the bracket slot.

There should be absolutely no movement of the teeth for at least four weeks before taking presurgical models: either stone or virtual.

The stabilizing wire must fit passively to be effective.

Surgical hooks attached to the brackets or arch wires are usually necessary to facilitate maxillomandibular fixation and to provide a means of using postsurgical elastic guidance or traction.

Fixtures attached to the brackets include ball hooks or K (Kobayashi) hooks (Fig. 5.1).

They may distort or break during the surgery.

Fixtures attached to the arch wire include crimped-on hook and soldered pins.

The use of postsurgical elastics may activate the arch wire, possibly creating unwanted orthodontic movements.

Inter-occlusal records or bite registration in centric relation (CR)

Diagnostic casts that are mounted on an anatomic fully adjustable articulator in CR

Facebow transfer to mount maxilla

Radiographic exam

Clinical data collection

Photographic records

Facial measurements

Diagnostic casts/digital dental scan

Centric relation record with fiducial markers

Cone beam computed tomography (CBCT) or CT scan

Final occlusion established by surgeon

Data transfer to service center

Planning specifics – order form (osteotomy design, order, and anticipated movements)

Used to aid in making a skeletal diagnosis . Patient is held in adjusted natural head position.

Lips relaxed, mandible in retruded contact position, and teeth lightly in occlusion.

Assess the inclination of the various facial planes.

Used to assess the AP position of the maxilla and mandible.

May show asymmetries of condylar ramal height/size between the left and right (inferior borders do not coincide). Ensure radiograph taken correctly, verify with AP cephalometric.

Can be used to assess the relationship of the maxilla to the cranial base.

Can visualize the posterior airway space.

Can assess growth by looking at the cervical vertebrae along with a growth chart.

The goal of surgery is not to give patients cephalometric normal values, instead it is used as a guide to treat the clinical picture.

Used to examine the dentition.

Can assess the temporomandibular joint anatomy.

Assess for presence of third molars.

Assess for pathological lesions/entities.

Can assess the inclination of roots (could be supplemented with periapical radiographs to view interdental osteotomy sites).

Used to assess the position of the inferior alveolar canal and entry to ramus.

Degree of sinus pneumatization.

Used for gross facial asymmetries and for planning surgical treatment. Scan should be obtained at a high spatial resolution with no motion artifact.

The patient’s CT/CBCT scan is reoriented by the computer engineers to reflect their NHP for more accurate planning. To produce accurate CAD/CAM splints, occlusal surfaces from CT or CBCT scans are replaced with a high-resolution laser scan from stone models or an intraoral scanner to create a composite model.

CT/CBCT can be reformatted into orthopantogram. Also allows assessment for TMJ, third molar, interdental osteotomy site, and IAN nerve canal position.

Will highlight significant facial asymmetry and can quantify excess or deficiency with tracing and measuring films. This film also allows the surgeon to further evaluate for skeletal cants of maxillae, mandible, and chin point.

Evaluate for U or V shape mandible, may have combination. V shape favors IVRO for setback. U shape favors BSSO for setback.

An ideal time to obtain presurgical records is 2 weeks prior to the planned surgery date. If custom plates (patient-specific plates) are to be used, then at least a month of lead time is needed to have time to plan and manufacture them.

Don’t take models until after the final rectangular orthodontic arch wire has been in place to be passive – ideally 4 weeks or more.

To be used in model surgery itself.

Facilitates fabrication of occlusal wafer splints.

Frontal full face with lips in repose.

Frontal full face with animation.

45-degree oblique (three-quarter) with lips in repose.

Right and left profile view in natural head position (NHP), in repose, full smile, and lips together.

Right, center, and left view with teeth in occlusion.

Maxillary and mandibular occlusal view.

An examination of the face is performed with the patient in adjusted NHP.

Facial thirds – The ideal face in both males and females is horizontally divided into equal thirds by horizontal lines at the hairline (Tr), glabella, the subnasale (Sn), and menton (Me’) (Fig. 5.2).

The ratio of middle third to lower third vertical height of face should be 5:6.

Racial differences need to be considered.

The “Rule of Fifths” – the face is divided sagittally into five symmetric and equal parts and each of the segments should equal the width of one eye (Fig. 5.3).

The outer canthi should coincide with the gonial angles.

The medial canthi should coincide with the alar bases of the nose.

The inter-pupillary distance should coincide with the corners of the mouth.

Maxillary and mandibular dental midlines should be coincident to facial midline.

Important midline structures are glabella (G), nasal bridge (NB), nasal tip (Pn), the midpoint of the philtrum of the upper lip (F), dental midline (DM), and the midpoint of the chin (Pog’).

Assess maxillary and mandible dental midlines in relation to each other.

Mandibular dental midline in relation to the mid chin point should coincide.

Smile and tooth-lip relationship.

Upper lip should expose full crown length in males and with 2 mm gingival show in females.

Normal tooth exposure on repose is 2–4 mm. Greater than 4 mm indicative of lip incompetence. Patient may display mentalis strain and have a tendency for mouth breathing.

Supraorbital rim projects beyond the most anterior projection of the globe of the eye.

Glabella should be coincident with the base of the nose.

Assess nose, cheeks, and paranasal area.

A vertical line perpendicular to constructed horizontal is drawn through soft tissue glabella (G’).

Pog’ should be 1-4 mm behind this line.

For maxillary AP position, Sn should be 6 ± 3 mm ahead of the line.

For mandible AP position, Pog’ should be 1-4 mm behind the line.

Angle formed by tangent line to columella and upper lip. Normal range is 85–105 degrees.

More acute in males and obtuse is more attractive in females.

Acute in class III.

Obtuse in class II.

Influenced by lip support, lip thickness, lip strain, and magnitude of the overjet.

Tracings of lateral cephalograms utilize stable hard and soft tissue points to aid in diagnosis, changes in growth, and treatment of dentofacial deformities (Fig. 5.6).

Skeletal age – serial hand-wrist radiographs.

Deceleration of growth – serial cephalometric radiograph.

Open bite

Excessive gingival show and/or excessive incisal show (resting and/or smiling)

Acute nasolabial angle

Excessive gingival show and/or excessive incisal show (resting and/or smiling)

Maxillary protrusion

Steep mandibular plane

Posterior open bite

Incisors not visualized at rest

Minimal to no incisor show with smiling

Incisors not visualized at rest

Minimal to no incisor show with smiling

General anesthesia with nasal intubation.

Place K wire at nasofrontal suture and take measurement to lower edge of maxillary incisor orthodontic bracket. This is an external vertical reference marker that can be used when complicated movements are to be done.

Full-thickness maxillary vestibular incision from one zygomatic maxillary buttress to the other (leave at least 5 mm of nonkeratinized mucosa to facilitate closure).

Bony exposure superiorly via this full thickness mucoperiosteal flap.

Bluntly dissect to the nasal aperture and protect the nasal mucosa by lifting it up with a freer elevator, stay just shy of the infraorbital nerve and tunnel to the pterygoid plates bilaterally. The soft tissue posteriorly can be protected with a neuro-patty soaked in local anesthesia and a small retractor.

Dissect anterior nasal spine free, dissect nasal floor off the palatal shelf using a freer.

Bone markings can be used to measure subsequent maxillary movement (internal reference marks).

Horizontal cut (or stepped cut) from posterior maxilla to piriform rim bilaterally.

If impacting, use a caliper to measure bone to be removed and cut a wedge out.

Lateral nasal wall osteotomies completed with guarded osteotome.

Nasal septum separated with nasal-guarded osteotome.

Pterygoid plate osteotomies with pterygoid osteotome (vector should be anterior and inferior).

If multiple-piece LeFort planned, place vertical interdental osteotomies at this time (cut arch wire if not already segmentalized by the orthodontist).

Induced hypotension (50–65 mm Hg MAP) is helpful to control bleeding. Patient must have an A-line.

Down fracture with simple digital pressure or gently with Rowe maxillary disimpaction forceps or Tessier mobilizers.

If multi-piece is planned, cut palatal paramedian osteotomy just lateral to nasal septum. This region represents thin bone and thick palatal tissue, reducing the chance of palatal tear.

Place splint securely to the dentition.

Intermediate or final splint used to position maxilla with maxillomandibular fixation (MMF).

Rotate the maxillomandibular complex up. Use a single finger to lift up complex to first point of contact. Grind as needed to achieve the correct vertical position. Do not force up or will pull condyles down out of fossae and bite will be open once you release the MMF.

Plate maxilla into new position (plates should be at the piriform and zygomaticomaxillary buttresses).

Bleeding  – sources include the pterygoid plexus, posterior superior alveolar artery, greater palatine artery, terminal branches of the maxillary artery. The internal maxillary artery is normally 25 mm superior to the base of the junction of the pterygoid plates in a normal maxilla. The pterygoid osteotome is 15 mm in height, leaving a 10 mm margin of safety. Treatment: attempt pressure packing with gauze and/or hemostatic agent. If no resolution, try to identify vessel for cautery. If bleeding continues consider an interventional radiology intraoperative consult for embolization. With an extremely small maxilla, like in a cleft child or syndromic patient, a preoperative CT angiogram may be useful to identify these vessels.

Anterior Open Bite After MMF Release – etiology: condyles not seated in fossa or area of premature bony contact. Remove fixation and check for bony interferences. Ensure passive condylar positioning into fossa. Replace fixation.

Dental Iatrogenic Injury – recommend placement of osteotomies 5 mm above apices of roots. Observe, root canal therapy if symptomatic, or extract. Teeth may remain insensate up to around 5 years.

Cut Palatal Mucosa During Multi-Piece – For a small tear, perform a simple suture repair and continue with the case. For large tear, consider replacing maxilla to original position . Do not attempt to raise flap of defect as it may further compromise blood supply and lead to avascular necrosis. The treatment in this case requires local irrigation and cover with a non-compressive splint. Formal closure is performed when revascularization is confirmed if the region has not closed spontaneously.

Vertical Posterior Maxillary Wall Fracture – check globe for increased pressure. Fracture of the pyramidal process of the palatine bone can cause injury to vessels or contents of the globe. Intraoperatively redirect fracture with osteotome. Postoperatively check globe pressure, changes in visual acuity, proptosis of the globe, and pupillary response. Ophthalmology consult may be indicated. If pressures are high, may require CT orbit with contrast for evaluation or emergency lateral canthotomy.

Anterior Maxillary Wall Fracture – attempt plating.

Midline Discrepancy – etiology: error introduced into workup/mounting/or splint fabrication. Reposition maxilla by utilizing facial midline or dental midline or stable jaw.

Decrease in Maxillary Perfusion – as denoted by poor capillary refill or purple gingiva. Replace and fixate maxilla to original position , check to ensure stents are not impinging tissue. Keep area clean to prevent infections with chlorhexidine and antibiotics until resolved. For severe delayed vascular compromise, consider hyperbaric oxygen.

Cut Endotracheal Tube – tube transfer/reintubate. Consider tracheostomy or submental intubation.

Nosebleed (Postoperative) – pack nose with nasal packing. If not controlled with packing, then return to the operating room to take maxilla down and control bleeding. Consider embolization.

Trigeminocardiac Reflex – stop stretch on maxillae. Further anesthetize soft tissue to decrease sensitivity of CN V. Atropine or glycopyrrolate may be required to complete surgery.

Epiphora – more common in high LeFort osteotomies due to damage of nasolacrimal system, nasoseptal deviation, or swelling. If no resolution after 6 weeks, CT scan to r/o source. May require dacryocystorhinostomy or nasoseptoplasty depending on etiology.

Pseudoaneurysm – patient may complain of build-up pressure with release. Bleed may be early or late. CT angiogram with interventional radiology consult.

Nasal Septum Deviation or Buckling – suture septum to the ANS to prevent deviation. Trim cartilaginous septum or maxillary crest for buckling.

Infection – obtain imaging. Antibiotics, incision and drainage, debridement. If hardware is source of infection, then remove appropriate hardware, replace if clinically acceptable.

Hardware Failure – replace hardware and consider more rigid fixation.