causes of skeletal maocclusion
- trauma
- pathology
- congenital
- developmental
congenital causes of skeletal malocclusion
- clefts
2. syndromes
developmental causes of skeletal malocclusion
- malocclusion
2. condylar hyperplasia
most malocclusions are caused by what?
developmental causes
trauma that causes skeletal malocclusion
- condylar fracture
2. radiation therapy
pathology causing skeletal malocclusion
- TMJ internal derrangement
2. acromegaly
congenital syndromes that cause skeletal malocclusion
- ectodermal dysplasia
- Treacher Collin’s syndrome (mandibulofacial dysostosis)
- hemifacial microsomia (Goldenhar’s syndrome)
tx of skeletal malocclusion
- growth redirection
- orthodontic camouflage
- orthognathic surgery
orthodontic camouflage accentuates what?
dental compensations
orthodontic camouflage is the opposite movement of what?
pre-surgical orthodontics
T/F: orthodontic camouflage has minimal discrepancy
true
T/F: orthodontic camouflage may possibly be less stable than other means of tx’ing skeletal malocclusion
true
what may be compromised with orthodontic camouflage ?
- esthetic
2. perio
T/F: in order to treat skeletal malocclusion with growth redirection, patient needs to be done growing
false, must have remaining growth
what should be considered with growth redirection?
TMJ
which tx option has limited correction possible?
growth redirection
T/F: patients undergoing growth redirection may have issues with compliance and may face burnout
true
orthognathic surgery
combined orthodontics and surgery used to manage a skeletal malocclusion
advantages of orthognathic surgery
- increased stability
- decreased tx time
- improved occlusion
- improved esthetics
indications for orthognathic surgery
- skeletal discrepancy with masticatory difficulty
- impingement on palatal tissue
- speech difficulty
- OSA (obstructive sleep apnea)
- psychosocial problems
- esthetics
how long does pre-surgical ortho take?
12-18 months
phase of treatment for orthognathic surgery
- pre-surgical ortho
- surgery
- post-surgical ortho
how long does post-surgical ortho take?
6 months
T/F: only ppl with convex facial profiles have normal occlusion
false, all facial types can have a normal occlusion
how is general facial form defined?
by appearance of the N’ -A- Pg’ line
general facial form is a general agreement among what?
- soft tissue profile
- skeletal features
- dental features
T/F: general facial form gives an overall impression and does not identify specific problems
true
straight profile indicates what?
optimal relations of maxilla and mandible to each other and to the cranial base
T/F: ppl with straight profiles can include some convexity at younger ages
true
ppl with straight profiles usually are what skeletal and dental class?
1
convex profile indicates what?
disproportional relationship with either…
- protrusive maxilla
- retrusive mandible
- combo of both
ppl with convex profiles usually are what skeletal and dental class?
2
concave profile indicates what?
disproportional relationship with either…
- retrusive maxilla
- protrusive mandible
- combo of both
ppl with concave profiles usually are what skeletal and dental class?
3
T/F: as a general rule, dental and skeletal relationships often agree
true
what can be used as a guide for skeletal relationships?
- overjet
2. molars and overjet relationships
deformities that can lead to orthognathic surgery
- class 2 deformites
- class 3 deformities
- open bite
class III deformities?
- maxillary AP hypoplasia
- mandibular AP hyperplasia
- vertical maxillary deficiency
class II deformities?
- maxillary AP hyperplasia
- mandibular AP hypoplasia
- vertical maxillary hyperplasia
what percent of US Caucasians are class 2?
10%
what percent of the US Caucasian class 2 population needs surgery?
2%
what percent of US Caucasians are class 3?
2.5%
what percent of the US Caucasian class 3 population needs surgery?
40%
work-up of tx
- ceph analysis
- problem list
- orthodontic prediction
- surgical prediction
- model surgery
- virtual model surgery
the ceph analysis generally supports what?
the profile and intraoral exam
what is the purpose of model surgery?
- reproduce on mounted models what the surgical plan is
2. fabricate surgical stents
vertical position is determined by what in surgery?
k-wire placed in nasion
AP position is determined by what in surgery?
the stent
transverse is determined by what in surgery?
by the stent
surgical procedures for mandible?
- vertical ramus osteotomy
- BSSO (sagittal split)
- anterior subapical
- total subapical
- anterior horizontal osteotomy (genioplasty)
T/F: bilateral sagittal split ramus osteotomy (BSSO) is extraoral
false, intraoral
bilateral sagittal split ramus osteotomy (BSSO) has a potential for what type of injury?
IAN
T/F: you can only do advancement with bilateral sagittal split ramus osteotomy (BSSO)
false, can do advancement or set-back
why might bilateral sagittal split ramus osteotomy (BSSO) not be stable when used to treat anterior open bite?
counterclockwise rotation
what is possible with bilateral sagittal split ramus osteotomy (BSSO)?
stable rigid internal fixation
T/F: bilateral sagittal split ramus osteotomy (BSSO) is commonly done in the maxilla
false, mandible
maxillary surgical procedures
- anterior segmental
- posterior segmental
- lefort I
- high lefort (II and III)
when was lefort I osteotomy developed?
1975
what can lefort I osteotomy do?
- move maxilla in all planes
- stable treatment of anterior open bite
- allow segmentalization of the maxilla
T/F: lefort I osteotomy has high morbidity
false, low
T/F: an internal rigid fixation is possible with lefort I osteotomy
true
skeletal deficiency secondary to oligodontia
ectodermal dysplasia
what makes cleft patient different?
- large maxillary AP deficiencies
- scar tissue
- velopharyngeal (VP) incompetence
- vascular compromise
- palatal and nasolabial fistulas
large AP moves
distraction
surgery is indicated for patients with obstructive sleep apnea if what?
- pts is not obese
- unable to tolerate CPAP
- no evidence of redudant pharyngeal soft tissue
what is the morbidity of orthognathic surgery?
very limited
how long is the hospital stay after orthognathic surgery?
overnight hospital stay
T/F: orthognathic surgery can be performed as outpatient (OMFS clinic)
true
T/F: sensory nerve deficit is possible with orthognathic surgery
true
T/F: intermaxillary fixation (wiring of teeth together) is rarely needed for patients that have undergone orthognathic surgery
true
where are incisions made during orthognathic surgery?
intraoral
what is the satisfaction rate after orthognathic surgery?
98%