and Obstructive Sleep Apnea

div epub:type=”chapter” role=”doc-chapter”>

© Springer Nature Switzerland AG 2021

R. Reti, D. Findlay (eds.)Oral Board Review for Oral and Maxillofacial Surgerydoi.org/10.1007/978-3-030-48880-2_5

5. Orthognathic and Obstructive Sleep Apnea

Myron R. Tucker1  , Richard G. Burton2  , Aaron D. Figueroa3  , Vincent Carrao4, Riddhi Patel5, Bryan Weaver6  , Gregg A. Jacob7   and Joseph W. Ivory8
(1)

Louisiana State University, Department of Oral and Maxillofacial Surgery, New Orleans, LA, USA
(2)

University of Iowa Hospitals and Clinics, Hospital Dentistry Institute, Iowa City, IA, USA
(3)

University of Iowa Hospitals and Clinics, Hospital Dentistry Institute, Oral and Maxillofacial Surgery, Iowa City, IA, USA
(4)

Mount Sinai Hospital, Oral & Maxillofacial Surgery, New York, NY, USA
(5)

Metrohealth Hospital, Cleveland, OH, USA
(6)

Ruby Memorial Hospital, Oral and Maxillofacial Surgery, Morgantown, WV, USA
(7)

Northeast Facial and Oral Surgery Specialists, Florham Park, NJ, USA
(8)

Dwight D. Eisenhower Army Medical Center, Oral and Maxillofacial Surgery, Evans, GA, USA
 
 
Richard G. Burton
 
Aaron D. Figueroa
 
Bryan Weaver
 
Gregg A. Jacob
Keywords

Skeletal facial deformityOpen biteTransverse discrepanciesDental compensationTooth size discrepancyArch alignmentSurgical hooksCentric relationCentric occlusionModel surgeryVirtual surgical planningLateral cephalogramOrthopantogramSubmental vertexLeFort I osteotomyBSSOIVROGenioplastyScleral showNegative vectorFacial thirdsCheek bone–nasal base–lip contourFacial midlineCephalometric analysisNasolabial angleSteiner analysisWits appraisalGrowth evaluationMaxillary hyperplasiaMandibular hypoplasiaVertical excessMaxillary hypoplasiaMandibular hyperplasiaTrigeminocardiac reflexCondylar sagPseudoaneurysmSARPEHunsuck modificationDal Pont modificationEpker modificationBad splitCondylar resorptionHierarchy of stabilityCleft lip and palateDistraction osteogenesisOSAPolysomnographyAHIMueller’s maneuverFujita classificationREM sleepSTOP BANGEpworth Sleepiness ScaleBMIMallampati scoreNasopharyngoscopyPosterior airway spaceCPAPStanford protocolUPPPTracheostomyGenioglossus advancementTelegnathic surgery

Indications for Orthognathic Surgery

When dentofacial deformities cannot be corrected by conventional orthodontic compensation, including growth modification and camouflage techniques as well as for treatment of OSA.

Anterior-Posterior Discrepancies

  • 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).

Vertical Discrepancies

  • 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.

Transverse Skeletal Discrepancies

  • 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.

Other Indications for Orthognathic Surgery

  • 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.

Presurgical Orthodontic Goals

Decompensation of Teeth

  • 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.

Arch Alignment and Leveling

  • 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).

  • Create divergence of roots adjacent to interdental osteotomy sites.

    • To perform interdental osteotomies, space should be created between the lateral incisors and the cuspids or between the cuspids and first bicuspids ideally.

  • 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.

Arch Coordination

  • 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.

Final Presurgical Orthodontic Preparation

  • 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.

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Fig. 5.1

A. Kobayashi hook B. Ball hook. (Image courtesy of Erik Steenberg)

Surgical Workup

Traditional Model Surgery

  • Clinical data collection

    • Facial measurements

    • ROM/TMJ findings

    • Cranial nerve exam

  • Photographic records

    • Extraoral front relaxed and smile (natural head position), lateral with lips in repose, ¾ view. If you are using the GALL line, then lateral with smile is needed, and ensure no hair is covering forehead.

  • Facial measurements

    • Look for position of orbits

    • Position of ears

    • Alar width

    • Asymmetries and Cants.

  • 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

Virtual Surgical Planning

  • 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)

Radiography

Lateral Cephalogram

  • 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.

Orthopantogram

  • 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.

Computed Tomography

  • 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.

Posteroanterior Cephalogram

  • 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.

Submental Vertex

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

Presurgery Records

  • 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.

Dental Casts or Scanned in Dentition (STL Files)

  • To be used in model surgery itself.

  • Facilitates fabrication of occlusal wafer splints.

Facial Photographs

  • 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.

  • Additional – submental view.

    • To document mandibular and/or midface asymmetry.

    • To allow detailed analysis of nasal tip form in patients with abnormalities.

Intraoral Photographs

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

  • Maxillary and mandibular occlusal view.

Facial Examination

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

Frontal View

Vertical Facial Proportions

  • 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).

  • Upper third of the face, measured from trichion to glabella.

    • Deformities may indicate craniofacial deformity.

    • Assess eyebrow shape, position, and symmetry.

  • Middle third of the face, measured from glabella to subnasale.

    • Includes eyes, nose, and cheeks.

    • Scleral show and flattening of cheek bones/paranasal region may indicate midface deficiency.

    • The nose, center of the lips, and middle of the chin should fall along the true vertical line.

    • The cheek bone-nasal base-lip contour line evaluates harmony of the structures of the midface with paranasal area and upper lip.

  • Lower third of the face measured from subnasale to menton.

    • Lower third is further subdivided into upper one-third from subnasale to stomion superius (Sn-Sts) and lower two-thirds from stomion inferius to menton (Sti-Me’).

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

  • Racial differences need to be considered.

Transverse Facial Proportions

  • 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.

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Fig. 5.2

Facial thirds. (Courtesy of Dr. Damian Findlay)

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Fig. 5.3

Facial fifths. (Courtesy of Dr. Damian Findlay)

Facial Symmetry

  • 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.

  • Excessive tooth display at rest may be from:

    • Short philtrum height. Look for this in the cleft population.

    • Vertical maxillary excess.

    • Excessive crown height/length.

    • Lingually tipped maxillary incisors.

  • Inadequate incisor display may be from:

    • Excessive philtrum height; subnasale to upper lip is >22 mm.

    • Vertical maxillary deficiency.

    • Inadequate crown height.

    • Flared maxillary incisors.

Profile View

The Upper Third of the Face

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

  • Glabella should be coincident with the base of the nose.

The Middle Third of the Face

  • Assess nose, cheeks, and paranasal area.

  • Nose:

    • Lower nose projection can be affected by the anteroposterior (AP) position of the maxilla.

    • Alar base shape resembles isosceles triangle from worm’s view.

  • Cheek:

    • The lateral orbital rim lies 8-12 mm behind the globe.

    • The globe projects 0-2 mm ahead of infraorbital rim.

    • Malar eminence should be located 10-15 mm lateral and 15–20 mm inferior to the lateral canthus.

    • Cheekbone-nasal base-lip curve contour should be smooth, uninterrupted curve.

  • Paranasal Area:

    • Paranasal deficiency represented by flatness of cheeks is often present in patients with maxillary deficiency.

    • The nasolabial angle is normally 100 degrees ±10 degrees; it is greater in females than in males.

The Lower Third of the Face

  • Lower third face height: subnasale to soft tissue menton

    • Lower third divided into two portions:

      • Subnasale to wet line of upper lip (1/3)

      • Wet line of lip to soft tissue menton (2/3)

  • Lips:

    • Subnasale-pogonion line (lower facial plane) – the upper lip should be 3 ± 1 mm and lower lip 2 ± 1 mm ahead of the line

    • Interlabial gap normally 0–3 mm in repose

    • Upper lip length: 20 +/− 2 mm in females, 22 +/− 2 mm in males

    • Lower lip length: 40 +/− 2 mm in females, 44 +/− 2 mm in males

  • Labiomental Fold:

    • S-contour

    • Angle – 130°.

  • Chin-Throat Angle:

    • Normally 110 degrees – provides chin definition.

    • Chin adiposity and hyoid bone position effect angle.

Cephalometric Analysis

Soft Tissue Analysis

Maxillary and Mandible AP Evaluation

  • 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.

Nasolabial Angle

  • 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.

Lip Prominence

  • A line drawn from subnasale (Sn) to soft tissue pogonion (Pog’).

    • The perpendicular distance of upper lip ahead of this line should be 3 ± 1 mm, while lower lip should be 2 ± 1 mm.

    • The AP position of upper lip is an indication of soft tissue support by maxillary incisors.

  • Another way to measure it is by using subnasale vertical (SnV) – a vertical line drawn from subnasale perpendicular to true horizontal line.

    • The upper lip should be 1-2 mm ahead of this line.

    • Lower lip should be on or just posterior to SnV.

Chin Prominence (Fig. 5.4)

  • A line drawn through N′ perpendicular to FH is 0-degree meridian line.

    • Pog’ 0 ± 2 mm ahead of 0-degree meridian and 3 ± 3 mm behind SnV (subnasale vertical).

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Fig. 5.4

Chin prominence can be evaluated in relation to Frankfort horizontal (FH). A line drawn perpendicular through FH through soft tissue nasion is known as (0-degree meridian); soft tissue pogonion should be 0 ± 2 mm ahead of this line. A line perpendicular through FH through subnasale is known as subnasale vertical. Soft tissue pogonion should be 3 ± 3 mm behind subnasale vertical. (Image courtesy of Erik Steenberg)

Lower Lip-Chin-Throat Angle

  • Angle formed by a line drawn from Li to Pog’ and submental tangent line – 110 ± 8 degrees.

    • Acute in patients with mandible AP excess and/or macrogenia.

    • Obtuse in patients with mandible AP deficiency and/or microgenia.

  • Chin Throat Length

    • Measured from angle of the throat to Me’ (normal value 42 ± 6 mm).

    • Helps differentiate between mandibular excess and maxillary deficiency.

  • Facial Contour Angle

    • Formed by lines drawn from G’ to Sn (upper facial plane) and from Sn through Pog’ (lower facial plane).

    • Mean angulation is −12 degrees (Fig. 5.5).

    • Males tend to have a straighter profile (−11 ± 4 degrees), while females have slightly more convex profile (−13 ± 4 degrees).

    • Various facial deformities may produce the same facial contour angle.

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Fig. 5.5

The facial contour angle describes facial convexity or concavity. It is formed by the angle of the upper and lower facial planes. Averages are −13 ± 4 for females and 11 ± 4 for males. (Image courtesy of Erik Steenberg)

Skeletal Analysis

  • 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).

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Fig. 5.6

Cephalometric hard tissue points

Assess Maxillary AP Position

  • Steiner Analysis

    • Maxillary anteroposterior positions in relation to the anterior cranial base (S-N).

    • SNA of 82° is considered normal. An angle <82° indicates maxillary AP deficiency, while >82° indicates maxillary protrusion.

  • Ricketts Analysis

    • Ricketts analysis uses maxillary depth.

    • Measures angle at the intersection of FH line and the NA line.

    • An angle of 90 ± 4 ° is ideal. An angle less than 86° indicates retrognathia, while an angle greater than 94° indicates prognathism.

  • McNamara Analysis

    • Measures the distance from A point to Nasion perpendicular (a line that crosses N and is perpendicular to FH), normal range is 0-1 mm.

    • A negative number indicates retrognathia, while a positive number greater than 1 indicates prognathism.

Assess Mandibular AP Position

  • Steiner Analysis

    • Mandibular anteroposterior positions in relation to the anterior cranial base (S-N).

    • SNB of 80° is considered normal. SNB <80° indicates mandibular AP deficiency and a greater angle indicates mandibular excess.

  • Facial Angle (Downs Analysis)

    • Indicates relative AP position of mandible to cranium.

    • An angle formed by the intersection of the facial line, N-Pog’ line and FH line.

    • Mean is 82–95°.

  • McNamara Analysis

    • Measures the distance from Pog to N perpendicular (a line that crosses N and is perpendicular to FH).

    • An ideal number for mixed dentition is −8 to −6 mm, adult female is −4 to 0 mm, and adult male −2 to +2 mm.

Assess AP Maxillomandibular Relationship

  • Steiner

    • Provides an idea of anteroposterior relationship between maxilla and mandible.

    • A normal maxillomandibular relationship is indicated by ANB of 2°.

    • In class III cases, angle is <2 or even negative. In class II cases, angle is >2.

  • Wits Appraisal

    • Linear relationship between maxilla and mandible not influenced by cranium.

    • Points BO and AO are established by dropping perpendicular lines from A point and B point, respectively, onto the occlusal plane (OP) (Fig. 5.7).

    • The mean in male is BO 1 mm ahead of AO. In females, AO and BO coincide.

    • The measurement between AO and BO indicates the AP discrepancy between maxilla and mandible.

    • Small discrepancy between AO and BO indicates that the case can be treated orthodontically, while large discrepancy may indicate surgical correction.

  • Mandibular Plane Angle (Steiner)

    • Formed between mandibular plane (Go-Gn) and anterior cranial base (S-N), normal value is 32 degrees.

    • An angle ≥39° is considered high, ≤ 28° is a low angle.

    • Interprets the difference between anterior and posterior facial heights.

    • Increase in mandibular plane angle tends to have dolichocephaly, class II malocclusion, vertical maxillary excess, and apertognathia.

    • Decrease in angle is associated with bradycephaly, skeletal deep bite, and notched gonial angles.

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Fig. 5.7

Wits appraisal

Analysis of Dental Relationships

Maxillary Incisor Position

  • Steiner

    • AP position of incisor to maxilla.

    • The axial inclination should be 22° to NA and the most anterior point of maxillary incisor should be 4 mm ahead of NA.

    • The facial surface of maxillary incisor should be 4-6 mm ahead of the vertical line through A point.

Mandibular Incisor Position

  • Steiner

    • AP position of incisor to mandible (NB line).

    • Mandibular incisor angulation to NB line should be 25 ° and the most labial point of incisor should be 4 mm anterior to the line.

Occlusal Plane Angle

  • Steiner Analysis

    • Angle between the occlusal plane (OP) and anterior cranial base (S-N) – 14°.

    • High-angle individuals have relatively long anterior facial height, while low-angle individuals have vertically short anterior facial height.

Chin Assessment

  • Holdaway Ratio

    • Extend NB line to the inferior border of the mandible and compare the distance between L1 (incisal edge of mandibular incisor) and Pog from this line.

    • A ratio of 1:1 is ideal in males and 0.5–1 in females.

    • REMEMBER, this is only of value if lower incisors are in the proper position. Predictions for chin correction must be made with this in mind.

Growth Evaluation

  • Skeletal age – serial hand-wrist radiographs.

  • Deceleration of growth – serial cephalometric radiograph.

  • Six stages of cervical vertebrae maturation on lateral cephalometric radiograph.

    • The peak of mandibular and craniofacial growth corresponds to the peak in statural height growth, which corresponds to stages 3 and 4 of cervical vertebral maturation.

    • As cervical vertebrae mature through six stages, they develop a concavity on the inferior border and assume a more rectangular shape in both boys and girls.

LeFort (LF) Osteotomy

The LeFort osteotomy has a long history and has become the standard of care when performing maxillary osteotomies to achieve a change in maxillary position. The maxillary position can be changed in any one of three dimensions or a combination thereof. When deciding on maxillary position, we must be sure to have the correct diagnosis, which ultimately will guide our surgical plan and produce the best surgical result for the patient. Maxillofacial deformities are always determined by the physical exam which then may or may not be supported by radiographic findings.

The following list of maxillary diagnoses includes important physical findings that exemplify the specific diagnosis.

Maxillary hyperplasia can be one of the following or a combination thereof:

Posterior vertical excess

  • Open bite

Anterior vertical excess

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

Anterior posterior excess

  • Acute nasolabial angle

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

  • Maxillary protrusion

Maxillary hypoplasia can be one of the following or a combination thereof:

Posterior vertical deficiency

  • Steep mandibular plane

  • Posterior open bite

Anterior vertical deficiency

  • Incisors not visualized at rest

  • Minimal to no incisor show with smiling

Anterior posterior deficiency

  • Midface deficiency

    • Poor piriform rim support (flat to concave maxillary appearance)

  • Incisors not visualized at rest

  • Minimal to no incisor show with smiling

LeFort Osteotomy Technique

  • 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.

  • Check fractures and trim bony interferences of the septum and lateral walls.

    • Ensure complete mobility of the maxilla in three planes of space, should be able to passively move.

  • 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).

Complications with LeFort Osteotomy

  • 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.

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Jul 23, 2021 | Posted by in Oral and Maxillofacial Surgery | Comments Off on and Obstructive Sleep Apnea
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