Orthognathic Surgery Flashcards
What is thalassemia?
Produce a large amount of abnormal RBC’s everywhere. Effects maxillary more because it has sites of extra-medullary hematopoiesis where mandibular does not
What is the etiology of jaw deformities?
- Congenital
- cleft
- craniofacial - Developmental
- growth imbalance - Acquired
- traumatic
- pathologic infectious
What is glossoptosis? What is micrognathia?
Glossoptosis is downward displacement or retraction of the tongue which may cause no fusion of hard palate –> cleft palate
Micrognathia is an undersized/small jaw
What is condylar hypoplasia?
It is when the condyle ramus does not grow
- the posterior maxilla does not descend
- steep occlusal plane
- clockwise facial rotation
- bilateral micrognathia (bird face)
- unilateral hyperplasia
- depends on condylar growth factor
What is mandibular excess (condylar hyperplasia)?
- could be from tumor
- hemimandibular hyperplasia (3-D enlargement of the mandible, terminates at the symphysis, canted maxilla, presents before puberty, anterior teeth tilted to affected side)
- hemimandibular elongation
- mandible descends/maxilla follows
- bilateral/unilateral
What are the 5 questions/factors when diagnosing a dentofacial patient?
- Skeletal base
- Dental occlusion
- Soft tissue drop
- Functional problems
- Patient goals
How do you survey the facial skeleton?
- XYZ planes
- Facial exam
- Lateral and P.A cephalogram
- Natural head position
- Articulated facebow mounted studies
- Worms eye view
- Symmetry range
When you do a lateral assessment, what do you evaluate/observe?
Your observations are relative to the bell line
- upper lip/lower lip/chin
- facial thirds
- infraorbital paranasal evaluation
- nasolabial angle/labial mental
- mandibular plane angle
- mental cervical angle
What should you see in a balanced orthognathic position?
Upper lip is most predominant, lower lip behind it, then chin behind the lower lip
What is dental occlusion, dental compensation? Why is this important?
Dental compensation occurs as skeleton grows. It is where the dental occlusion compensates for the skeletal deformity.
This is important because before we can do surgery, we must decompensate the dental compensation (need dental discrepancy to reflect skeletal discrepancy.
Ex. Lower jaw grows forward –> less influence of tongue and lower lip increases –> lower teeth tip back (lingual inclination of incisors)
What is a normal occlusion?
The mesiobuccal cusp of the maxillary first molar is aligned with the Buccal groove of the mandibular first molar.
What is class I malocclusion?
It is where a normal molar relationship exist is but there is misalignment/crowding/cross bites/ or too much space
What is class II malocclusion?
It is a malocclusion where the molar relationship shows the Buccal groove of the mandibular first molar is distally positioned to the MB cusp of the maxillary first molar, thus the anterior maxillary teeth are forward – overbite
What is a class III malocclusion?
The lower molars are far forward and do not fit into their corresponding upper molars. The Buccal groove of the mandibular first molar is mesial lay positioned to the MB cusp of maxillary first molar. Underbite
What do you see in a class II malocclusion for dental compensation?
Since there is overbite, we could see facially inclined mandibular incisors for dental compensation. Must decompensate before treatment of other possible problems such as small airway
What do you see in a class III malocclusion for dental compensation?
Lower jaw too forward so the lower teeth are inclined lingually for dental compensation
What is skeletal apertognathia?
It is skeletal open bite – often associated with airway problems, open mouth breathing
Why are we concerned about the soft tissue drape over hard tissue?
- are the lips competent?
- is there peri oral straining? - mentalis, obicularis oris
- upper lip/lower lip/chin relationship
What is the purpose of orthognathic surgery?
It is to reposition one or both jaws to correct irregularities, but orthodontics is also required to make sure the etch are in correct position after surgery.
Goals:
- improve ability to speak, chew, breath, and appearance
What are some functional problems that could occur due to deformity?
- Poor dental health
- periodontal considerations
- occlusal attrition
- balancing occlusal forces
- dental trauma
- long term prosthetic considerations - Airway issues
- Mastication
- Pain
- Speech
- Self image
- Soft tissue injury
- Whole life impairment
Name some examples of functional health problems that arise in the category of dental health
- Open bites produce dental breakdown
- Retrognathic patient will often manifest periodontal problems
- Class III is associated with Incisal wear
Name some examples of functional problems that arise in the category of mastication
- Normal diet?
- Incise food
- Create and swallow a food bonus
- Dietary assessment
- Pain or difficulty chewing
What sorts of airway problems might a patient have from gnathic problems?
- Obstructive sleep apnea
- Snoring
- Nasal airflow
- Mouth breathing
- Exercise intolerance
*diminished airway can lead to decreased muscle tone
How is speech effected by these orthognathic problems?
- articulation (S and T sounds, lisping)
- phonation (hypo and/or hyper nasality)
- rapid conversational speech
- resonance, voice quality
Why do patients seek orthognathic surgery?
- appearance - most common
- function
- pain
- speech
- social anxiety
What are the five basic surgical options for orthognathic surgery?
- Le fort I osteotomy
- Vertical oblique osteotomy
- Sagittarius split osteotomy mandible
- Genioplasty
- Dentoalveolar segmental series
What is the purpose of osteotomies?
They are segmental surges so that we can divide alveolar segments to permit differential movements. This can be for the maxilla or mandible.
What is the vascular basis of osteotomy
Idk wtf the ppt is trying to say but just know that there should always be a vascular pedicle
What is intra-oral vertical/oblique ramus osteotomy (IVRO)?
This is a procedure that allows you to move the mandible back/down/up (but mostly back). This procedure requires jaw immobilization and has a low risk for mental paresthesia
What is Sagittarius splitting mandibular ramus osteotomy?
In this procedure there is an incision in the bone that splits the mandible in the Sagittal plane. The start of the cut can be on the lingual aspect of the mandible and a chisel is used to separate the pieces so you get the Sagittal split. Buccal and lingual pieces slide on each other and it goes right through canal. It allows lower jaw to be moved forward or back – plates placed to stabilize but does not require jaw immobilization
This requires rigid internal fixation and has an increased risk of mental paresthesia
What are some complications of orthognathic surgery?
- Bleeding
- Airway
- Malunion/nonunion
- Wound healing
- Relapse early/late
- Late growth
- Neuropathy/paresthesia
- Unhappy with facial change
- Nasal issues
- Fistula
- Facial pain
- Poor facial balance
What is distraction osteogenesis?
It is a technique of creating an osteotomy in a bone
After a latency period slowly separating these two bones to lengthen them while creating new bone in the osteotomy site without bone grafting
This technique also allows for tissue expansion (muscles, nerve, skin, and blood vessels). It decreases the potential for relapse through contraction of the wound. Can advance maxilla over large distances with more stability and can be done in any age group
How does distraction osteogenesis work?
- Osteotomy
- Latency
- lasts from time of fracture to application of traction
- hematoma forms
- clot formation and bone necrosis
- revascularization of clot and cell proliferation
- lasts 1-3 days - Distraction
- bone is stretched
- bone can be manipulated to lengthen and even bend - Consolidation
- Device removal and remodeling phase
What are some surgical challenges?
- Discrepancies typically in the maxilla and greater than 1 cm
- Patients have had multiple surgical procedures of the hard and soft tissues of the palate which creates scar tissue
- More difficult to mobilize and advance with standard corrective jaw surgery
How do we decrease relapse possibilities?
We compromise the surgical treatment plans by splitting the difference – maxilla is advanced, mandible is set back, and the occlusal plane steepened to stay within the soft tissue envelope thus decrease the potential for relapse
What does Lefort I osteotomy allow you to do with the maxilla?
It is primarily used to move maxilla forward
What is the procedure for a Lefort I with down fracture?
- Remove bone interferences to advance maxilla
- Place dis tractors prior to down fracture to align vectors, remove complete osteotomy and replace Distractors
- Advance maxilla and make sure it moves freely forward
- Latency is 7 days then start distraction
- Rate is 1mm/day
- Move to endpoint then let it consolidate for at least 16 weeks
- Remove dis tractors
What is the role of the orthodontist?
- Diagnosis and treatment
- Decompensate dentition
- Align dental arches
- Surgical anchorage
- Manage post-op occlusion
