British Journal of Orthodontics, Vol. 26, No. 2, 81-88,
June 1999
© 1999 British Orthodontic Society
The William Houston Gold Medal 1997
Joy Hickman, B.D.S., F.D.S.R.C.S., M.PHIL, M.ORTH, R.C.S., M.S.C.D.
Department of Orthodontics, Glasgow Dental Hospital and School NHS Trust,
378,
Sauchiehall
Street, Glasgow G2 3JZ, UK
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Introduction
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The William Houston Gold Medal is presented to the candidate achieving the most outstanding
and
meritorious performance in the M.Orth. examinations of the Royal College of Surgeons of
Edinburgh.
Five clinical cases are presented by the candidate for the purposes of the examination. Two of
these are
described: the first is a Class III malocclusion with ectopic maxillary canines and the second is a
mild
Class II division I malocclusion with crowding.
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Case Report 1
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A 14
-year-old Caucasian female presented complaining of the appearance of the gaps
between her upper front teeth (Figure 1a-i). Her medical history was
unremarkable and,
although a
regular dental attender, there had been a recent unscheduled visit to her General Dental
Practitioner
following the loss of a restoration.
Extra-oral clinical examination revealed a straight profile with an increased lower anterior face
height
and Frankfort-mandibular planes angle. There was no facial asymmetry or mandibular
displacement on
closure. The lips were competent with effort, and tongue activity, speech and mandibular
function were
all normal.
Intra-oral examination revealed the maxillary canines were unerupted, although |3
was
palpable palatally. The location of 3| was less certain by palpation, but the labial
inclination of 2| increased the suspicion of a more buccal placement. Oral hygiene
was
generally good, but there was a large temporary dressing in the lower left mandibular first molar
and an
occlusal amalgam in the lower right mandibular first molar.
Examination of the dental arches demonstrated mild crowding in the lower labial segment with
an
increased curve of Spee and an arch length discrepancy of 3.5 mm. In the upper arch, there was
mild
spacing in the labial segment, but severe crowding in the buccal segments with virtual exclusion
of the
unerupted 3|3 and a space discrepancy of 11.5 mm. In occlusion there was a Class
III
incisor relationship with the overjet and overbite just positive, except on the left lateral incisors,
which
were edge to edge. Centrelines were coincident and the buccal segment relationship was a quarter
unit
Class II bilaterally.
Panoramic radiography confirmed the presence of all permanent teeth, including unerupted
maxillary
canines and third molars (Figure 2a). There was gross caries in the lower
left
first permanent
molar. The
3| was located high at the apex of 2| and less than 45 degrees to the
occlusal plane with an enlarged follicle. The |3 was more favourably angulated.
Vertical
parallax with the panoramic and upper standard occlusal radiographs suggested 3|
was
in the arch line and confirmed the palatal location of |3 (Figure 2b).
The roots of
the
maxillary incisor teeth were sound. Cephalometric evaluation supported the clinical impression
of a
Class III skeletal pattern with a degree of dentoalveolar camouflage. The corrected ANB angle
was
-2.0 degrees and the Wits difference was -6.0 mm, with the upper incisors slightly proclined at
114
degrees and the lower incisors retroclined at 87 degrees. The lower face height was only
marginally
increased and the maxillary-mandibular planes angle was actually reduced, probably due to the
inclination of the palatal plane.
The Dental Health Component of the Index of Treatment Need was 5i and the pretreatment
weighted
PAR score was 29.
The aims of treatment were:
- Camouflage of the antero-posterior skeletal discrepancy.
- Relieve upper and lower arch crowding, incorporating teeth of poor prognosis.
- Increase or maintain the present overbite and overjet to achieve a Class I incisor relationship.
- Produce a good buccal segment cusp fossae relationship and a functional occlusion.
The treatment plan was as follows:
- Oral hygiene instruction and dietary advice.
- Removal of 3|3 (referral to the Oral and Maxillofacial 6|6 Surgeons)
- Upper and lower pre-adjusted Roth 0.022 prescription fixed appliances to level, align and close
space using predominantly intra-arch mechanics. The molar relationship was to be a full unit
Class II between the upper first molars and the lower second molars, and the upper first premolars were
to
mimic the maxillary canines.
- Retain and monitor the development of the lower third molars.
Active treatment consisted of 20 visits over 24 months. Levelling and alignment was achieved
with
super-elastic nickel-titanium archwires and lower arch space closure commenced on 0.020-inch
round
stainless steel wire. Forward movement of the lower second molars was hampered by their
position
behind the distal of the upper first molars and they also showed a tendency to roll lingually. This
was
managed by alignment of 7|7, and progression to upper and lower 0.019 x
0.025-inch stainless steel wires with 2 mm of intrusion, introduced distal to the upper and lower
second
premolars, and buccal crown torque in the lower arch wire. Once the lower second molars were
sufficiently clear of the upper first molars, upper arch space closure was also commenced. Light
Class
II elastics (3-ounce, 5/16-inch) were used in the later stages of treatment to aid forward
movement of the lower second molars. An upper standard Hawley and lower spring Hawley were
fitted at debond (Figure 3a-i).
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Case 1 Assessment
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Treatment aims were achieved in this case addressing the patients aesthetic concerns and
eliminating the
poor quality lower first molars. As the patient appeared to have completed the majority of her
growth
at presentation, orthodontic camouflage of her Class III skeletal discrepancy was deemed
appropriate.
The lower arch extraction pattern was less than ideal in terms of both arch length discrepancy
and
anchorage balance, but was determined by the teeth of poorest prognosis. The 3| was
unfavourably positioned, both vertically and horizontally, with cystic degeneration of the follicle
and, on
balance, was felt to be the most appropriate unit to be lost for relief of crowding in this quadrant.
The
|3 could probably have been aligned with relative ease, but would have necessitated
loss
of a premolar unit, and the decision was made at the treatment planning stage to maintain
symmetry and
accept 4|4, due to their reasonably good position and suitable morphology.
Space closure was principally completed by intra-arch mechanics, although light Class II elastics
were
used judiciously towards the end of treatment. This may be regarded as a high risk strategy in the
camouflage of a Class III malocclusion, but careful visit by visit monitoring of the overjet and
overbite
with these mechanics enhanced forward movement of the lower molar and maintenance of the
lower
labial segment position. A group function occlusion with a full unit Class II molar relationship
has been
established with good aesthetics, although increased mesio-palatal rotation of |4
would
have improved this further.
Cephalometric superimposition revealed that only a small amount of favourable growth occurred
during
the treatment period (Figure 4). The antero-posterior relationship of the
skeletal bases
remained largely
unchanged and the lower incisors have been maintained close to their original inclination (Table 1). The
upper and lower third molars will be kept under review.
Post-treatment weighted PAR score = 4
Percentage reduction in PAR score = 86 %
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Case Report 2
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A boy aged 12 years, 10 months had been under review to the orthodontic department following
initial
referral by his General Dental Practitioner at the age of 9 years for crowding in the mixed
dentition. His
main concern at the last review was the appearance of his upper canine teeth (Figure
5a-i).
Previous
interceptive orthodontic treatment had been carried out and involved loss of all four deciduous
canines
at 10 years of age, together with a course of oral hygiene instruction. This was followed by loss
of
lower first premolars at 11 years.
On examination, he had a mild Class II skeletal base with an average Frankfort-mandibular
planes
angle and normal lower anterior face height to total face height ratio. The lips were competent,
and their
were no signs of TMJ dysfunction or pathology.
Intra-orally he presented in the permanent dentition having had earlier loss of lower first
premolars. Oral
hygiene was generally good, but with some further improvement required. The lower dental arch
had
residual mild crowding in the lower labial segment with little space remaining from the premolar
extractions and an increased curve of Spee. In the upper arch there was severe crowding, with a
9-mm
arch length discrepancy and 2| palatally displaced.
In occlusion, the overjet was increased to 5 mm due to the mesio-labial rotation of |1.
The 2| was in crossbite, and associated with a small forward and left lateral
mandibular
displacement on closure with a 1-mm shift of the lower centre-line to the left in maximum
intercuspation.
The overbite was increased and complete. The molar relationship was Class I bilaterally with the
canines on the right side three-quarters of a unit Class II and half a unit Class II on the left.
Panoramic radiography confirmed the presence of de-veloping third molars. Shadowing in the
occlusal
aspects of the lower first and second molars was suggestive of caries. Cephalometric evaluation
revealed a Class II skeletal base with an ANB of 5.5 degrees and a Wits difference of 5 mm. The
vertical facial proportions, and upper and lower incisor inclinations were within normal limits.
The IOTN score (DHC) was 4d and the weighted PAR score was 41. Standard pretreatment
records
were taken prior to planning, but unfortunately the clinical photographs had to be repeated, and
at
this
stage the extractions and restorations had been completed by the General Dental Practitioner (Figure
5a-h).
The aims of treatment were to produce a Class I, mutually protected functional occlusion,
camouflaging
the mild Class II skeletal discrepancy with:
- Elimination of the mandibular displacement.
- Relief of upper arch crowding, and upper and lower arch alignment.
- Reduction of overbite and overjet.
The treatment plan was as follows :
- Render caries free and improve oral hygiene.
- Extraction of 4|4.
- Bond and band upper and lower arches with Tip-Edge® TP Orthodontics, Inc., 100 Center
Plaza, LaPorte, IN (4635)0, USA appliance, initially leaving off the premolar brackets
and 2|. Use 0.016-inch stainless steel arch wires with cuspid circles and bite opening
bends. Start full time Class II elastics running directly to power pin on 3|.
- Once sufficient space is available bond 2| and align.
- When overjet and overbite reduction are complete engage premolars.
- Proceed to 0.020-inch stainless steel wires with an increased upper curve of Spee and reverse
lower
curve of Spee, using necessary intra-arch mechanics to close space and correct centrelines.
- Place 1-mm molar offsets and 7-10 degree toe-ins just prior to the end of space closure.
- Place 0.(0215) x 0.028-inch stainless steel archwires and Sidewinder®
T.P. Orthodontics Inc., 100 Plaza, La Porte, IN (4635)0, U.S.A. springs to upright and
torque teeth.
- Detail the occlusion.
- Retain and monitor the third molars.
Treatment consisted of 18 visits over 21 months. There were some initial problems with elastic
wear,
but sufficient space was available to align 2| after 4 months. Despite good overbite
reduction, a lower acrylic clip over removable appliance was required to disclude the anterior
teeth to
give enough occlusal clearance for bond placement (Figure 6a). Once
2| was
over the
occlusion and the displacement eliminated the lower centreline was shifted to the right (Figure 6b). A
clockwise Sidewinder® was added to the lower right canine to favour centreline correction in
Stage
I (Figure 6c). Stage II took just over 3 months as there was little residual
extraction space and
Stage III
was of 8 months duration, with hyper-activation of the Sidewinder® on 2| to
express the appropriate buccal root. At debond an upper standard Hawley and lower spring
Hawley
were fitted (Figure 7a-i).
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Case 2 Assessment
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Treatment aims have been achieved despite initial problems of compliance with elastic wear,
which
prolonged the early stages of treatment. After elimination of the mandibular displacement, a
centreline
discrepancy was evident, unfavourably influencing the lower arch length discrepancy. The early
loss of
lower premolars may have improved the lower labial segment alignment in the shorter term, but
the
resultant loss of space and potential lower arch anchorage, in this case, seem to outweigh any
positive
benefits.
Cephalometric superimposition shows the patient has grown in a vertical direction, with little
help from
horizontal growth during correction of the malocclusion (Fig. 8). The
overjet
has been reduced
predominantly by movement of the upper incisors. There has also been a small amount of upper
and
lower incisor proclination during treatment, and may be related to inadequate adjustment of the
anterior
torque, to compensate for the bite sweeps in the full dimensional Stage III arch wires (Table 2). A
cephalometric assessment at the end of Stage II may have been helpful and indicated that
night-only
headgear support was required to limit the forward movement of the dentition seen in Stage III
Tip
Edge®.
Oral hygiene levels were inconsistent during treatment and, despite vigorous hygienist support,
gingival
hyperplasia was present, mitigating against alignment of the second molars as a finishing
procedure. The
prognosis for the long-term stability of the lower labial segment must be guarded, although
relapse of
2| should be controlled by the good buccal root torque achieved.
Post-treatment weighted PAR score = 2
Percentage reduction in PAR score = 95 %.
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Acknowledgments
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I would like to express my thanks to all my clinical supervisors for their excellent teaching and
guidance
throughout my postgraduate training at Cardiff Dental Hospital and East Glamorgan Hospital,
Pontypridd. Special thanks must go to Peter Nicholson and Peter Durning, who supervised the
above
cases.
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Introduction
Case Report 1
