Orthognathics Flashcards
What impairments and comorbidities often exist with orthognathic patients
1-Appearance
2-Function
-mastication
-speech
-breathing
-socialization
3-TMJ disease
4-OSA
5-Myofascial pain
What does a presurgical work-up require for orthognathic surgery
1-Clinical photographs
2-Dental models
3-Cephalograms
4-Panoramic radiograph
Upper Third Facial Exam (5 pts)
1-Area form the hairline (trichion) to glabella
2-Assess eyebrow shape, position, and symmetry
3-Male eyebrows are larger, more horizontal and level with the supraorbital rims.
4-Female eyebrows slope upward, peaking about 10 mm above the supraorbital rims
5-The superior orbital rims should project 10 mm in front of the cornea
Middle 1/3rd facial exam (6 pts)
Lower 1/3rd facial exam ( 8 pts)
base of the nose
subnasale
subnasale
base of the nose
menton
base of the chin
What is the nasolabial angle on average
100 degree +/- and is usually greater in females
What is the average range for incisal show at rest and what factors affect it
0.5-5 mm
-Decreases with age
-Females show more than males
-Ethnicity, Whites>Asians>Blacks
-Upper lip length
-Incisal attrition
What does lip width coincide with?
inter pupillary distance
What does intercanthal distance coincide with?
the alar base
What is the normal chin-throat angle
110 degrees
The upper lip should constitute _% of the lower third
30%
Steiner analysis with SNA angle
It was believed that the cranial base was alike in al individuals but now we know there is a large variation with the cranial base (SN) so this should be used with cuation
Ricketts analysis
Uses maxillary depth
-Draw the NA line (line that crosses the Nasion and A point)
-Draw Frankfort horizontal line (line that crosses the upper margin of the external auditory canals (porion) and the lowest point of the infraorbital rim (orbital)
-Measure the angle at the intersection of these lines
porion
upper margin of the bony external auditory canal
orbitale
lowest point of the infraorbital rim
McNamara Analysis
Measures the distance from A to N perpendicular
1-Draw N perpendicular ( a line that crosses N and is perpendicular to FH
2-Measure the distance from A to N perpendicular
3-If A is in front of N perpendicular, the number is positive, if it is behind, the number is negative
What is the purpose of Steiner, Ricketts, and McNamara analyses
To determine the AP maxillary position
Measurements associated with AP maxillary retrognathism and prognathism
How can you assess the AP mandibular position?
-Steiner analysis using the SNB position
-Downs analysis using the facial angle
-McNamara analysis measures the distance from Pog to N perpendicular
Steiner analysis for AP mandibular position
-Uses the SNB angle
-As with the SNA angle, this measurement should be interpreted with caution because of possible distortion caused by an anterior cranial base that is either too steep or too flat.
Downs analysis for AP mandibular position
Uses the facial angle
1-Draw the facial plane as a line that crosses N and pogonion (Pog)
2-Measure the angle at the intersection of the facial plane and FH (Frankfort horizontal)