orthognathic surgery

Orthognathic surgery

Involves the surgical manipulation of the elements of the facial skeleton to restore the proper anatomic and functional relationship in patients with dentofacial skeletal anomalies

History of the orthoganthic Procedures

Mandibular osteotomies 1846 Hullihan - Anterior mandibular subapical osteotomy and setback 1906 Blair - Mandibular body osteotomy 1907 Blair - Horizontal osteotomy of the ramus, external approach 1925 Limberg - Posterior oblique vertical ramal osteotomy, external approach 1927 Wassmund - Inverted "L" ramal osteotomy, external approach 1939 Kazanjian - Beveled horizontal osteotomy of the ramus, extraoral approach 1943 Schuchardt - Step horizontal osteotomy of the ramus, intraoral approach 1945 Caldwell and Letterman - Vertical ramal osteotomy, external approach 1955 Obwegeser - Sagittal split ramal osteotomy 1968 Caldwell et al - "C" ramal osteotomy 1970 Hebert, Kent, and Hinds - Intraoral vertical ramal osteotomy

History of the orthoganthic Procedurescontinue

Maxillary osteotomies 1927 Wassmund - LeFort I osteotomy with the pterygomaxillary junction left intact; elastic forces used to bring the maxilla forward 1928 Axhuasen - Segmental osteotomy through the mid palate 1948Schuchard - Staged LeFort I osteotomy, followed by pterygomaxillary separation; external traction used to bring the maxilla forward 1949 Moore and Ward - Horizontal transection of the pterygoid plate 1965 Obwegeser - Fully mobilized the maxilla; in a single step brought it into the predicted position Osseous genioplasty procedures 1943 Hofer - Horizontal sliding osteotomy of a receding chin (extraoral) 1957 Trauner and Obwegeser - Intraoral approach to osseous genioplasty

Orthognathic Surgery

Historically, the ability to reposition the mandible in a stable manner long preceded the ability to reposition the maxilla. As a consequence, many patients underwent only mandibular surgery to correct a primary maxillary deformity. The specialty of orthognathic surgery did not fully develop until Obwegeser demonstrated the possibility of repositioning the maxilla in a stable consistent manner in 1965 and reported simultaneous repositioning of the maxilla and mandible in 1970

Orthognathic Surgery

The word orthognathic comes from the Greek word “ortho”, meaning to straighten, and “gnathic: meaning jaw. Orthognathic surgery thus means to straighten a jaw. Defining a straight jaw versus one that is not requires determining the degree of deviation from a specified population norm

face is more than the upper and lower jaw when deformities extend to involve the cranio-orbital skeleton, evaluation and management expand the scope of maxillofacial surgery to craniofacial surgery. Thus, orthognathic or maxillofacial surgery is a subset of craniofacial surgery

Orthognathic Surgery

Correction of maxillofacial deformities requires careful analysis of the soft tissue clinical examination supporting photographs skeletal evaluation with standardized radiographs dental evaluation with study dental casts. Formulation of a treatment plan thus requires close cooperation of the surgeon working with the dentist, the orthodontist, and at times the restorative prosthodontist. Unlike many surgical procedures, outcome depends not only on the surgical procedure but also on a multitude of factors that begin long before the actual surgery as well as on control of the variables long after surgery


Dentofacial deformities requiring Orthognathic surgery
Includes a broad population of patients with deformities of congenital Developmental (1.5-2 million in USA) traumatic origin

Clinical assessment

should be directed specifically at evaluating the relative position size of each of the facial skeletal elements the degree of zygomatic projection the maxillary and mandibular positions in space relative to each other and to the cranial-orbital regio The nasolabial angle upper lip length lip competency labial-mental sulcus Any facial asymmetry should be noted along with the relationship of the maxillary dental mid line to the mandibular dental mid line the dental mid lines to the facial mid line The intraoral examination should focus on the dental alignment within each arch and relationship of the dental arches to each other The degree of dental display on repose and smile also should be recorded with the amount of gingival display.

Orthognathic Surgery

Facial balance typically is assessed by dividing the face in thirds. The upper third is from the anterior hairline (trichion) to the glabella, the middle third from the glabella to the subnasale, and the lower third from the subnasale to the menton. When each of the thirds is equal, the face is said to be balanced and of "ideal" proportions. Additionally, in profile view the face should have a slight degree of convexity as measured from the glabella to the subnasale to the menton. Excess facial convexity, flatness, or concavity is felt to be less than ideal However, facial proportions are only idealized concepts and have changed over time.

Maxillofacial deformities

can be divided broadly into 3 major categories: dental dysplasias skeletal dysplasias dentoskeletal dysplasias

Dental dysplasias

Dental dysplasias are limited strictly to malocclusions that result from abnormal spatial relationship of the dentition and not from the skeletal position of the upper and lower jaws. These can be corrected with orthodontic treatment

Skeletal dysplasias

In patients with skeletal dysplasia only, the dentition is in good alignment but the maxilla and/or mandible are dysplastic. Skeletal dysplasias require correcting the skeletal deformity without altering the occlusion. An example is a patient with retrogenia without retrognathia or a patient with hemifacial microsomia who has a normal maxillary-mandibular dental relationship but has an occlusal cant because of skeletal asymmetry

Dentoskeletal dysplasias

In dentoskeletal dysplasias, the dentition is malpositioned within each arch and with each other the skeletal relationship of the upper and lower jaws is abnormal An example is a patient with a maxillary sagittal and transverse width deficiency from a facial cleft. Correction requires aligning the dentition within each arch with orthodontic treatment and restoring the maxillary-mandibular dental relationship with skeletal osteotomies and repositioning In addition, dentoskeletal dysplasias can be classified further based on the position in space and on the volume or mass (whether deficient or in excess) of the individual elements. For example, the mandible can be of normal shape and volume but retrognathic in relationship to the maxilla, or it may be both retrognathic


Indications for orthognathic surgery
Include facial dysmorphism with and without functional implicationsِAn osseous genioplasty for a patient with retrogenia but without malocclusion should be considered for facial formIf the retrogenia is associated with retrognathism resulting in a malocclusion, orthognathic surgery is indicated for restoring the facial form and for functional occlusion Airway and speech are other indications when considering the functional need for orthognathic surgery Restoration of the normal anatomic relationship between the maxilla and mandible relative to the cranial base reestablishes the functional components (ie, form and function) of the facial skeleton

Contraindications of orthognathic surgery

Risk factors may alter the treatment plan or preclude surgery including underlying medical condition bleeding dyscrasias systemic disease local factors that may affect normal wound healing, compromised vascularity of the surgical region a patient with unrealistic expectations a noncompliant patient patients with poor oral hygiene.

(1) the descending palatine branch of the maxillary artery (2) the ascending palatine branch of the facial artery (3) the anterior branch of the ascending pharyngeal artery from the external carotid (4) the alveolar branches of the maxillary artery. With complete mobilization of the maxilla frequently the descending palatine vessels are disrupted and the mobilized maxilla derives its vascularity from the remaining sources, primarily the ascending palatine and pharyngeal vessels.

Radiographical exam

Cephalometric radiographOPGPeriapical……..………..Photograph Upper and lower dental casts

Analysis of the dentofacial skeleton is based on identifiable radiographic landmarks on a lateral cephalometric x-ray
Lateral cephalometric analysis of the facial skeleton based on Steiner analysis. The positions of the maxilla and mandible each are related spatially to the anterior cranial base and to each other. Note that normative values of the facial elements depend on a normal anterior cranial base inclination and length, which typically are altered in craniofacial conditions

Treatment phases

Preorthodontic preparatory phase Presurgical orthodontic treatment phase Surgical phase Postsurgical orthodontic phase Prosthodontic treatment phase

Surgical corrections

Mid face Lower face



Mandible
20
8 5


7.5
8
2
4

Surgical therapy

Well-established osteotomies including: LeFort I-type osteotomy LeFort II-type osteotomy LeFort III-type osteotomy maxillary segmental osteotomies sagittal split osteotomy of the mandibular ramus vertical ramal osteotomy inverted L and C osteotomies mandibular body segmental osteotomies mandibular symphysis osteotomies.

Most maxillofacial deformities can be managed with 3 basic osteotomies: the mid face with the LeFort I-type osteotomy, the lower face with the sagittal split ramal osteotomy of the mandible, and the horizontal osteotomy of the symphysis of the chin

The LeFort osteotomies are named after the 3 classic lines of weakness of the facial skeleton described by Rene LeFort in 1901. Complete craniofacial dysjunction by the LeFort III osteotomy allows the surgeon to alter the orbital position and volume, zygomatic projection, position of the nasal root, frontonasal angle, and position of the maxilla and to lengthen the nose. The LeFort II osteotomy allows the surgeon to alter the nasomaxillary projection without altering the orbital volume and zygomatic projection. The LeFort I osteotomy allows for correction primarily at the occlusal level affecting the upper lip position, nasal tip and alar base region, and the columella labial angle without altering the orbitozygomatic region.

Illustration of the transverse maxillary LeFort I osteotomy. The osteotomy is made with a reciprocating saw and completed at the pterygopalatine junction with a curved osteotome
Variation of midfacial osteotomies to correct differing degrees of midfacial deformities involving the zygoma


Sagittal split ramal osteotomy. Place the horizontal osteotomy superior to the inferior alveolar nerve foramen and continue partially through the body along the oblique line to the region of the second and first molar to complete the vertical osteotomy. Make the osteotomy through the cortex with a reciprocating saw and complete it with an osteotome along the buccal surface

COMPLICATIONS

LeFort Injury to Stensen duct Infraorbital nerve traction injury Unanticipated fractures (pterygoid plate, sphenoid bone, middle cranial fossa) Injury to the internal maxillary artery and its branches Ophthalmic and lacrimal duct injury Avascular necrosis Maxillary sinusitis Velopharyngeal insufficiency Nasal septal deviation and buckling Arteriovenous fistulas (carotid-cavernous sinus)

COMPLICATIONS

Bilateral sagittal split osteotomy Injury to inferior alveolar nerve: The risk of injury to the inferior nerve is a significant disadvantage of the sagittal split ramal osteotomy. The incidence of transection is reportedly 2-3.5%. The long-term neurologic deficit reportedly occurs to some degree in 10-30% of patients, although not all are symptomatic. When the sagittal split osteotomy is combined with an osseous genioplasty, nearly 70% of patients have some degree of neurosensory deficit at 1 year. This is the accepted tradeoff (benefits outweighing risks) that patients must accept in mandibular surgery. Bleeding (inferior alveolar artery, masseteric artery) Unanticipated fractures and/or unfavorable split Avascular necrosis Condylar resorption Malpositioned proximal segment

COMPLICATIONS

Osseous genioplasty Injury to mental nerve Inferior mandibular border contour irregularity Gingival recession

COMPLICATIONS

Common to all procedures Postoperative infection Hardware exposure Unanticipated fractures Devitalization of teeth Malunion and/or nonunion Malocclusion Relapse Injury to teeth Gingival recession and/or periodontal complications Respiratory decompensation Bleeding

Ideal facial proportions believed to be in aesthetic balance. Use these proportions as guidelines, as ideal proportions change over time, and the ideal result varies with patient expectations
Profile analysis illustrating the degree of facial convexity or concavity from an acceptable orthognathic norm

An overview of the clinical, radiographic, and dental evaluation used in planning orthognathic surgery


Lateral cephalometric analysis of the dentition within the skeletal framework.
Illustration of the role of presurgical dental decompensation in a patient requiring mandibular advancement. Dental decompensation is necessary to allow for proper degree of mandibular advancement and for postsurgical stability at the occlusal level. Note that the occlusion is made worse until corrected by skeletal advancement

Presurgical orthodontic management requires appropriate dental decompensation, alignment of the dentition within the individual arches, leveling of the curve of Spee, and coordination of the maxillary and mandibular dentition for postoperative stability

Illustration of mandibular deficiency. The patient underwent bilateral sagittal split ramal osteotomy and advancement
Illustration of mandibular excess. The patient underwent bilateral sagittal split ramal osteotomy and mandibular setback

Illustration of vertical maxillary excess, apertognathia, and mandibular retrognathia. The patient underwent LeFort I anterior-posterior differential maxillary impaction with sagittal split ramal osteotomy and mandibular advancement
Illustration of maxillary deficiency with relative mandibular excess. The patient underwent a modified LeFort I midfacial advancement that included the body of the zygoma