Download Guidelines for Building Facial Harmony and Stability

SUMMARIES
ANNUAL SESSION
Guidelines for Building
Facial Harmony and Stability
Presented by Wick Alexander, DDS, MSD, at the PCSO Annual Session, October 24, 2009.
Summarized by Dr. Bruce P. Hawley, PCSO Bulletin Northern Region Editor.
A
ccording to Dr. Wick Alexander, this is a difficult subject, particularly on account of the
stability criterion. He believes that there are
certain guidelines which, when followed, allow us to put
these two goals together and provide the best care for
the patient. There are six guidelines to building facial
harmony and producing excellent final orthodontic
results: anterior torque control, skeletal control, transverse control, occlusion, proper surrounding tissues, and
soft tissue profile and smile.
ANTERIOR TORQUE CONTROL
Strive to keep IMPA within 3° of the original position; exceeding this amount increases the likelihood
of instability. Exceptions would include convex and
concave profiles, along with deep overbite cases. Dr.
Alexander finds the use of -5° degree torque on lower
incisor brackets with .018 slot to be helpful, along with
using an initial flexible rectangular wire (e.g., .017x.025
Cu Niti), even with Class III elastics as needed. Interproximal enamel reduction is also an option. Upper
incisor to SN is optimally in the range of 101° to 105°. He
uses a pre-torqued upper incisor bracket with .017x.025
SS archwire in a .018 slot. Exceptions could include a
vertical skeletal pattern, and high and low angle cases.
Finally, maintaining an interincisal angle between 130°
to 135° is also a key established norm.
SKELETAL CONTROL
Control vertical relationships by keeping SN-MP within
3° of the original value. Use high pull headgear on high
angle cases, and squeezing exercises as appropriate.
In the sagittal dimension, control between 1° to 3°.
Headgears hold the maxilla while the mandible grows
forward, for both maxillary protrusive and mandibular
retrusive Class II cases. Dr. Alexander believes that the
facebow headgear is the best Class II orthopedic appliance, generally used in his hands for eight to nine hours
per night for six to twelve months in growing Class II
patients. Lower incisor inclination changes tend to be
insignificant. The exceptions to the use of headgear are
no growth or compliance—then it simply won’t work! The
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only real modality for the correction of Class III cases is
face mask therapy.
TRANSVERSE CONTROL
Maintain the original mandibular intercanine width
within 1mm, in both nonextraction and extraction cases.
All of the research supports the avoidance of excessive
expansion of lower 3-3 width for long-term stability. An
exception would include lingually erupted lower canines,
which can be expanded. Control lower intercanine width
with your final archwire, which you can superimpose
over the original study model in order to verify.
Maxillary intermolar width between 34mm to 38mm
is another important criterion. You can use expanded
maxillary archwires, expanded headgear face bow, or
RPE as needed. While the lower intercanine width should
not be significantly expanded, one can expand maxillary
intercanine width along with upper and lower premolar
and first molar widths (see TABLE).
AMOUNT OF STABLE EXPANSION (MM)
MAX.
MAND.
3-3
2.65
0.49
4-4
4.01
3.73
5-5
4.57
1.85
6-6
3.88
2.57
The final arch form should be ovoid, with every arch form
similar yet individual and most within one standard
deviation. Maxillary intermolar width and mandibular
intercanine widths will, of course, be contributing factors to the arch form. Dr. Alexander likes to start with
the maxillary arch and contour the maxillary archwire to
fit the untreated mandibular arch as a template. He then
expands at the molars to give the correct molar overjet.
Expand or constrict the mandibular posterior archwire
as needed (there are no exceptions to this).
PCSO BULLETIN • WINTER
2009
ANNUAL SESSION
OCCLUSION
Both maxillary and mandibular incisor roots need to
diverge, with the lower lateral incisor roots nearly parallel to the roots of the lower canines, without exception.
Roots in the extraction sites should, of course, be parallel. Upright mandibular first molars in both normal and
deep bite cases. This helps level the lower arch and maintain the overbite. He uses a -6 degree tip routinely except
in open bite cases. The mean long-term lower first molar
tip is 4.55°. Level the mandibular arch with a reverse
curve of Spee, tied back. This tends to extrude the bicuspids 2-4mm with a slight (around 0.5mm) intrusion of
lower incisors. Extrusion of the bicuspids is our desire
and slight extrusion of lower molars with 6° tip back is
acceptable. He heat treats his archwires and strives to
keep the mandibular anterior teeth as close as possible
to their original positions. A good final occlusion results
from proper bracket placement and archwire sequencing, orthopedic appliances, and elastics. Dr. Alexander
likes to attach a Class II elastic to the maxillary lateral
incisors rather than maxillary cuspids in order to have
a more horizontal force vector. He uses vertical zig zag
finishing elastics (3/4 inch, 2 ½ oz being the heaviest) on
every case, centered in the bicuspid regions.
PERIODONTAL AND TMJ HEALTH
SUMMARIES
the tip of the nose. For a nice smile, the facial and dental
midlines should be symmetrical (use dental floss to
verify). The smile line should be such that the upper lip is
at the gingival line, +/- 2mm while the patient is smiling
broadly. Dental display helps determine in a deep bite
case whether to put an upper accentuated curve of Spee
in the maxillary archwire or a reverse curve of Spee in
the lower archwire. The smile arc refers to the lower lip
being parallel to the maxillary incisal edges in smiling.
This is achieved orthodontically from proper bracket
placement, finishing, enamoplasty, and the use of anterior boxed elastics. The buccal corridor should display
teeth, not dark spaces. Achieve this by reaching proper
maxillary intermolar width (34mm to 38mm), adequate
rotation of upper first molars, proper tips and torques,
and ovoid arch forms. This seems to work well most of
the time.
In the final analysis, Dr. Alexander likes to keep the
mandibular intercanine dimension as close as possible
to the original, and he builds the rest of the of the occlusion around this. By following these guidelines, we can
provide the utmost in harmonious faces and maximize
the stability of our final orthodontic results.

Poor oral hygiene tends to cancel long-term stability;
the roots and periodontal soft tissues need to be healthy.
With respect to the TMJ, have canine and anterior guidance (good bracket placement helps), treat to CR, and
work in the last six months of treatment to attain maximum interdigitaition.
BALANCED SOFT TISSUE PROFILE AND SMILE
In the ideal profile, the lips should be touching while
relaxed. The esthetic (E-) line touches the chin and lips
and bisects the nose. A proper diagnosis to determine
whether to extract or go nonextraction is critical in
order to position the teeth so that the lips will be relaxed
in repose. In the Asian population, the E- line contacts
WINTER
2009 • PCSO BULLETIN
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