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• Orthognathic surgery

  The alignment of the jaws to normalize the relationship between the jaws themselves and the rest of the craniofacial complex

  
• Causes of dentofacial deformities

  • Inherited tendencies
  • Prenatal problems
  • Systemic conditions that occur during growth
  • Trauma
  • Environmental influences
• Development of proper craniofacial form and function

  • The spheno-occipital and sphenoethmoidal synchondroses and the nasal septum have their own intrinsic growth potential
  • The majority of the face growth occurs in response to adjacent soft tissue and functional demands
• Normal growth of the face


  Downward and forward with lateral expansion
• Malocclusion and associated abnormalities

  Result from alterations in the pattern of growth or rate of growth
• Treatment objectives of orthognathic surgery

  • Obtain functional occlusion with teeth in the most ideal position
  • Correct underlying skeletal disharmony
  • Obtain maximum esthetic results
  • Skeletal stability
• Evaluation of patients with dentofacial deformities

  • Requires integration between orthodontics and surgery
  • Treatment by orthodontics alone may result in acceptable occlusion but compromise in facial esthetics
  • Treatment by surgery without orthodontics may result in improved facial aesthetics but less than ideal occlusion
  • Patients often have other problems requiring periodontic, endodontic, complex restorative, and prosthetic considerations
• Assessment of orthognathic patients

  • General assessment
  • Facial assessment
  • Profile evaluation
  • Intraoral assessment
  • Radiographic evaluation
• Angle's classification

  Class I skeletal: Normal anteroposterior relationship of maxilla and mandible

  Class II skeletal: Mandibular base posterior to maxillary base

  Class III skeletal: Mandibular base anterior to maxillary base

  
• Angle's classification is inadequate for describing dentofacial skeletal deformities as it does not specify which element requires correction

  
• Pre-surgical treatment phase

  • Periodontal considerations
  • Restorative considerations
  • Orthodontic considerations
• Objectives of pre-surgical orthodontics

  • Decompensation of dentition
  • Alignment of arches
  • Coordinate arches
  • Leveling of arches
• Timing of orthognathic surgery

  During growth (interceptive surgery)

  After growth cessation (definitive surgery)
• Ideal orthognathic planning objectives

  • Determine final post-surgical dental occlusion
  • Demonstrate post-surgical soft tissue facial appearance
  • Determine magnitude of skeletal hard tissue movement necessary
• Methods of treatment planning


  • Model planning
  • 2D soft tissue profile prediction planning
  • 3D computerized surgical planning
• Advantages of 2D soft tissue profile prediction planning

  • Ability to predict facial changes from surgical correction

  Facial images easily evaluated by patients
• Disadvantages of 2D soft tissue profile prediction planning

  • Predictions limited to 2D lateral profile

  Inability to accurately predict every surgical change
• Advantages of 3D computerized surgical planning

  • Improved precision of surgical correction

  Visualisation of soft tissue changes from skeletal movements

  Splint design using CAD-CAM
• Dentofacial abnormalities frequently require a combination of surgical procedures in the mandible, maxilla and midface area
• Repositioning skeletal and occlusal components

  1. Requires CT acquisition

  2. 3D imaging

  3. Laser scanning

  4. Digital photographs superimposed on 3D CT data

  5. Virtual model of face constructed

  6. Movement of skeletal components produces soft tissue changes

  7. Splint designed using 3D computer technology

  8. Splint construction using CAD-CAM rapid prototyping
• Surgical treatment phase

  • Dentofacial abnormalities frequently can be treated by isolated procedures in the mandible or the maxilla and the midface area
  • Surgical correction frequently requires a combination of surgical procedures
  • Orthognathic surgery is accomplished in the operating room, with the patient under general anesthesia
  • Post-surgical hospital stay usually ranges from 1 to 4 days
• Mandibular excess

  Excess growth of the mandible results in skeletal class III (mandibular prognathism) and in an abnormal occlusion with class III molar and canine relationships and a reverse overjet in the incisor area
• Mandibular excess

  • Facial features include prominence of the lower third of the face, particularly in the area of the lower lip and chin in the anteroposterior and vertical dimensions
  • In severe cases, the large reverse overjet may preclude the patient's ability to obtain adequate lip closure without abnormal strain of the orbicularis oris muscles
• Bilateral sagittal split osteotomy (BSSO)

  1. Accomplished through an intraoral incision along the external oblique ridge

  2. Lingual cortex osteotomy

  3. Buccal cortex osteotomy (vertical cut)

  4. Osteotomies connected by an osteotomy along the anterior border of the ramus

  5. Osteotomy splits the ramus and posterior body of the mandible in a sagittal fashion, which allows the setback or advancement of the mandible

  6. Fixation can be achieved by transosseous wiring, bicortical screws, or monocortical plate and screws
• Complications of BSSO

  • Damage to the inferior alveolar nerve and/or the lingual nerve
  • Unfavorable split of the mandible (bad split)
  • Pain, swelling, and limitation of mouth opening
  • Hematoma and infection
  • Immediate or delayed skeletal relapse
  • Worsening of preoperative TMJ symptoms
• Vertical ramus osteotomy

  1. Originally performed through an extraoral approach

  2. Now can be performed through an intraoral approach using an incision similar to that used in BSSO

  3. Osteotomy done by an angulated oscillating saw
• Complications of vertical ramus osteotomy

  • Injury to the inferior alveolar and/or lingual nerves
  • Condylar sagging
  • Condylar subluxation
  • Skeletal relapse
  • Bleeding
  • Infection
  • Fibrous union
• Mandibular deficiency


  Mandible deficiency results in skeletal class II (mandibular retrognathism) with a retruded position of the chin as viewed from the profile aspect

  
• Mandibular deficiency

  • Facial features include an excess labiomental fold with a procumbent appearance of the lower lip, abnormal posture of the upper lip, and poor throat form
  • Intraorally, there are usually class II molar and canine relationships and an increased overjet in the incisor area
• Genioplasty

  1. Performed through an intraoral incision from canine to canine

  2. Inferior portion of the mandible is osteotomized, moved forward, and stabilized by transosseous wiring, screws, or plates

  3. Can also be used for vertical reduction or augmentation and correction of asymmetries

  4. Alloplastic materials can occasionally be used to augment chin projection
• Maxillary excess


  Excessive growth of the maxilla may occur in the anteroposterior, vertical, or transverse dimensions

  
• Maxillary excess

  • Vertical maxillary excess may result in elongation of the lower third of the face, a narrow nose, excessive incisive and gingival exposure, and lip incompetence
  • Anteroposterior maxillary excess results in a convex facial profile usually associated with incisor protrusion and a class II occlusal relationship

  
• Le Fort I osteotomy

  1. Performed through an intraoral incision extending from the first molar to the contralateral first molar

  2. Osteotomy achieved by bur or reciprocating saw, extending from the lateral nasal rim to the pterygomaxillary junction

  3. Lateral nasal wall and nasal septum osteotomies and pterygomaxillary separation completed using osteotomes and mallet

  4. Downfracturing and complete mobilization and trimming of the maxilla completed

  5. Fixation of the maxilla in the planned occlusion best achieved with four plates
• Complications of Le Fort I osteotomy

  • Infraorbital nerve injury resulting in temporary paresthesia
  • Bleeding from injury to large vessels
  • Fibrous union
  • Acute and chronic maxillary sinusitis
  • Nasal obstruction due to buckling and deviation of the nasal septum
  • Ischemic necrosis of the maxilla, ocular complications, and nasolacrimal apparatus dysfunction
• Maxillary and midface deficiency


  • Patients with maxillary deficiency commonly appear to have a retruded upper lip, deficiency of the paranasal and infraorbital rim areas, inadequate tooth exposure while smiling, and a prominent chin relative to the middle third of the face
  • Patients frequently have a class III malocclusion with reverse anterior overjet
• Le Fort I osteotomy for maxillary deficiency


  1. Maxilla can be repositioned inferiorly with bone grafting

  2. In severe midface deformities, Le Fort II or III type of osteotomy is necessary to advance the maxilla and malar bones and, in some cases, the anterior portion of nasal bones

  
• Combination deformities and asymmetries

  • Treatment may require a combination of maxillary and mandibular osteotomies (Bimaxillary orthognathic surgery) to achieve the best possible occlusal, functional, and aesthetic results
  • The most common combination is Le Fort I osteotomy and BSSO
• Distraction osteogenesis (DO)


  • Involves cutting an osteotomy to separate segments of the bone and the application of an appliance that will facilitate the gradual and incremental separation of bone segments
  • The gradual tension placed on the distracting bone interface produces continuous bone formation and adaptive changes in all surrounding tissues
• Phases of distraction osteogenesis

  1. Surgical phase

  2. Latency phase (7 days)

  3. Distraction phase (1 mm/day)

  4. Consolidation phase

  5. Appliance removal

  6. Remodeling
• Advantages of distraction osteogenesis

  • Elimination of the need for bone grafts
  • Better long-term stability
  • Less trauma to the TMJ
  • Decreased neurosensory loss