7 Step Cephalometric Treatment Plan

1. correct Mx incisor axial inclination: (female 56.8 ± 2.5 degrees) (male 57.8 ± 3.0 degrees) to Mx occlusal plane
2. correct Md incisor axial inclination: (female 64.3 ± 3.2 degrees) (male 64.0 ± 4.0 degrees) to Md occlusal plane
3. autorotate Md to 3.2 mm incisor overbite when the following occurs at 3.2 mm of overbite:
   • C I overjet LFI only has corrected the bite
   • C II overjet Md advancement will be necessary in step 4
   • C III overjet Md setback will be necessary in step 4
4. move Md to Mx
   • 3.2 mm incisor overjet
   • 3.2 mm incisor overbite (done in step 3)
   • 1.5 mm first molar overbite
5. set Mx incisor position (anteroposterior and vertical esthetically determined) vertical: (females 4.7 ± 1.6 mm) (males 4.0 ± 1.4 mm) incisor exposure under relaxed lip
   • anteroposterior: combination of STCA and clinical findings determine
   • mirror test at nasal base and upper lip extremely important
   • clinical nasal projection (long, normal, short)
   • clinical orbital rim, cheekbone, subpupil, and alar base contours (depressed, flat, normal, prominent)
   • clinical upper lip support (by incisor, gingiva, no support [air])
   • cephalometric upper lip anterior projection: (females 3.7 ± 1.2) (male 3.3 ± 1.4)
   • cephalometric upper lip angle (female 12.1 ± 5.1 degrees) (male 8.3 ± 5.4 degrees)
   • cephalometric upper lip thickness (female 12.5 ± 1.8 mm) (male 14.8 ± 1.4 mm)
6. set occlusal plane
   • occlusal plane determinants:
   • Mx occlusal plan to TV line (females 95.6 ± 1.8 degrees) (males 95.0 ± 1.4 degrees)
   • chin to TV line (females -2.6 ± 2.5 mm) (males -3.5 ± 1.8 mm)
   • appropriate facial change at alar base (never move nasal base posterior)
   • anterior: Mx incisor position set in step 5 is center of occlusal plane rotation
   • posterior: move Mx second molar superior or inferior with Mx incisor as center of rotation
   • may need to advance or retract class I maxilla and mandible to achieve correct nasal base support during step 6
   • remembers step 7 allows for 3-4 mm of chin augmentation or reduction
7. set ideal chin projection
   • chin osteotomy
   • Sn to Pog’ (females -2.6 ± 2.5 mm) (males -3.5 ± 1.8 mm)

The following may occur:

1. orthodontics only – steps 1, 2 and possibly 7 achieve occlusal correction and facial balance
2. lower jaw only – steps 1, 2, 3, 4, and possibly 7 achieve occlusal correction and facial balance
3. upper jaw only – steps 1, 2, 3, and possibly 7 achieve occlusal correction and facial balance
4. bimaxillary – steps 1 through 6 and possibly 7 are necessary to achieve occlusal correction and facial balance

Ratios of soft tissue to hard tissue changes:

True Vertical Line (TVL) anteroposterior position is based on clinical nasal projection (short, normal, long), clinical nasal base contour (depressed, flat, normal, prominent), clinical upper lip support ( by incisor, gingiva, no support [air] ), cephalometric upper lip angle (11 ± 3.5), and cephalometric upper lip thickness (13 ± 3.0). The TV line is generally placed on or near Sn. When midface retrusion is diagnosed the TV line is moved 1-3 mm anterior. Midface retrusion is defined by a long nose, deficient nasal base, poor incisor upper lip support, upright upper lip and/or thick upper lip. The true vertical line is oriented at a right angle to postural horizontal. Generally, the TVL is set 4-8 mm off of soft tissue glabella for CII patients. In the case of CIII patients the TVL may be set 0-4 mm off of soft tissue glabella. Frontal bossing and sloping foreheads also must be considered when assessing the distance from the TVL to soft tissue glabella.

from http://www.arnettcourses.com/

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