British Journal of Orthodontics, Vol. 26, No. 3, 179-190,
September 1999
© 1999 British Orthodontic Society
Rapid Palatal Expansion in Treatment of Class II Malocclusions
Aldo Giancotti, D.D.S., M.S.,
Antonella Maselli, D.D.S. and
Raffaella di Girolamo, D.D.S.
Department of Orthodontics, University of Rome `Tor Vergata', Ospedale
Fatebenefratelli – Osola Tiberina, Via Ponte Quattro Capi n°34, 00184 Rome,
Italy
 |
Abstract
|
|---|
A technique which combines the use of rapid maxillary expansion and fixed appliance
in growing patients, is presented. The treatment in three patients with Class II division 1
malocclusion and different skeletal patterns is described, and relative advantages
highlighted.
Key words: Rapid Palatal Expansion, Class II Malocclusion, Transverse Discrepancy
|
Introduction
|
|---|
In clinical observations of patients with Class II division 1 malocclusions there is often a
transverse discrepancy between the dental arches, generally due to a reduction in maxillary
width.
Staley et al. (1985
) has emphasized the
importance of evaluating
the transverse
discrepancy in Class II subjects. He also emphasized the transverse maxillary inadequacy and
posterior crossbite tendency in an adult Class II sample when compared with an adult Class I
sample. Therefore, according to the results of Tollaro et al. (1996), the presence of
posterior transverse interarch discrepancy (PTID), measured as the difference between the
maxillary and mandibular intermolar widths, could be considered as a possible functional cause
of
distocclusion.
In the same paper, Tollaro found that, the differences between molar widths, in a group of
adults with a normal occlusion was small and positive. When the teeth were in centric occlusion,
the molar width differences were significant in male and female II patients even with no visible
molar cross-bite.
A possible approach to the treatment of Class II malocclusion in growing patients is based on
resolution of transverse discrepancy in the first phase of treatment. The transverse co-ordination
can be accomplished by different modalities. Several authors have suggested that maxillary
widening can also be produced by the cervical headgear without any other appliances if the inner
bow of the headgear is widened (Ricketts R. M.,
1960; Bench et al., 1978;
Ricketts R.M., et al., 1979; Staley et al.,
1985).
However, the quad-helix and rapid palatal expander are more frequently used for inter-arch
discrepancy correction (Haas, 1970). Rapid
maxillary expansion (RPE)
has been used for more
than 100 years to correct maxillary skeletal base constriction. The use of the rapid palatal
expander for the correction of maxillary arch constriction in the treatment of Class II
malocclusions has rarely been suggested (Kirjavainen et
al., 1997). Warren (1993)
describes and illustrates a method of treating Class II patients with a headgear-expander
appliance.
This article presents the integration of RPE for transverse co-ordination in Class II
malocclusion.
|
Clinical management
|
|---|
The primary treatment goal was to correct the posterior transverse discrepancy between the
dental arches. The following treatment modulations were necessary to provide therapeutic
guidance in the approach to Class II connection.
All three patients treated were classified as Class II division 1 malocclusions. They presented
with bilateral Class II molar relationship in centric occlusion, bilateral Class II
deciduous/permanent canine relationship, protrusion of maxillary incisors, and absence of
posterior cross-bite.
The first step in all patients was palatal expansion. All the appliances described in this report
have the same type of expansion screw (Dentaurum Inc., Pforzheim, Germany) soldered on the
upper first molars only. The expander was activated 1.5 mm (six turns) in the first day
and
0.50 mm each successive day by a quarter turn in the morning and a quarter turn in the
evening. The patients were seen weekly and during each adjustment, the screw was extended
1–1.5 mm more (4–6 turns). The desired expansion was achieved when
the
maxillary arch was overcorrected by approximately 2–3 mm and the screw was opened at
least 11–14 mm. The screw was then fixed and the appliances was left in situ for
3 months for retention. When the expander was removed, a fixed pre-adjusted appliance was
inserted.
Initial alignment in both arches was accomplished with light steel or Ni–Ti arch wires
on a pre-adjusted edgewise appliance (bi-dimensional technique). The saggital correction was
obtained by using Class II elastics (6 oz/3/16) on 0.18 x 0.22-inch
rectangular
arches, while the patients wore a lip bumper in the lower arch for 14 hours daily. A segmental
torquing 0.018 x 0.022-inch arch was used in the lower arch with labial
root
torque. Depending upon the dentoskeletal characteristics of the patients, the vertical control was
considered as a key factor in order to plan the orthodontic mechanics. When vertical problems
are
present, intrusive forces need to be applied to posterior teeth to prevent their elongation during
treatment. To achieve this purpose high-pull or posterior bite-block were placed in
hyperdivergent
subjects.
|
Case report 1
|
|---|
A 9-year-old female presented with a convex soft-tissue profile, dolichofacial growth with
retrognathic posteriorly inclined mandible and lip incompetence at rest (Figures
1– 3). The
patient had a Class II division I malocclusion with an extreme overjet. She was in mixed
dentition,
and presented with a narrow upper arch. The upper anterior teeth were protruded and
over-erupted. The lower anterior teeth were retroclined and slightly crowded (Figures
4–8). Cephalometric analysis revealed a convex skeletal profile, she had a
7-degree ANB, a
high mandibular plane angle (34 degrees), the maxillary incisors were at 7 mm and 29 degrees to
NA, and the mandibular incisors were at 2 mm and 15 degrees to NB (Figures
9–11, Table
1).
Treatment progress
The treatment objective was to achieve a symmetrical Class I occlusion without extractions
and to improve facial appearance. The first phase of the treatment involving transverse expansion
of the upper arch was produced with RPE. The expansion screw was soldered on the upper first
molars and was activated for 1 week until a sufficient overcorrection was gained (2–3
mm). Then the screw was fixed and left in situ for about 90 days for retention
(Figures
12–15). The alignment of the upper arch was completed with a continuous
stainless steel
archwire (0.016-inch), while a segmental torquing 0.018 x
0.022-inch
archwire was used in the lower arch, with labial root torque placed at incisors and molar teeth.
Class II elastics were used 14 hours daily (Figures
16– 20). The
patient was seen regularly
every 4 weeks for 6 months. Minor adjustment of occlusion was performed with continuous
archwires during the following 3 months.
Results
The treatment time was 24 months; a full Class I cuspid and molar relationship was achieved
(Figures 24–28). There was little change
in the drape of the soft
tissues and lip competence
(Figures 21–23).
Cephalometric analysis shows an improvement in mandibular plane angle (Go–Gn:33
degrees), in pogonion position (pog to N: 1 mm), in maxillary incisor angulation (to NA: 20
degrees), in lower incisor angulation (to NB: 23 degrees), and in interincisal angle (133 degrees)
(Figures 29–32, Table 1).
|
Case report 2
|
|---|
The second patient was a 10-year-old female, presenting with a convex profile, protruding
upper incisors and lip incompetence (Figures
33–35). She had a
Class II malocclusion in
the mixed dentition, with an increased overjet and overbite, and crowded maxillary and
mandibular incisors (Figures 36–40).
Cephalometric analysis
revealed a convex skeletal
profile with an increased mandibular plane, severe Class II malocclusion and a mandibular
retrusion (Figures 41–43, Table 2).
Treatment progress
Treatment objectives were:
(1) to control the occlusal plane;
(2) to promote counterclockwise rotation of the mandible with intrusion of the
posterior teeth;
(3) to obtain Class I occlusion.
The first phase was based on expansion of the upper arch with RPE. After over-correction,
the screw was fixed and a headgear (high-pull), was prescribed to be worn 12–16 hours
per day. The headgear controlled the vertical dimension by intrusion of the upper first molar and
promoted autorotation of the mandible to prevent an increase of the lower facial height
(Figures
44–48). A lower lingual-arch was placed to maintain lee-way space. She wore
a `
bite-block' 16 hours per day to obtain the intrusion of lower first molars. After 12
months, the upper and lower incisors were bonded and aligned with archwires progressing to
segmental 0.018 x 0.022-inch torquing wires. Class II elastics from the
lower
first molar to the upper arch were used for 3 months to promote settling (Figures 49–56).
Final alignment was performed with full fixed appliances and Ni–Ti archwire.
Results
Active appliances were removed after a total of 24 months of treatment. A good occlusion
was achieved with a Class I canine and molar relationship (Figures 57–60). Comparison of
pre- and post-treatment cephalometric tracings showed little change with vertical height
reduction
(33 degrees) Figures 65–68, Table 2.
Because of
proclination of the incisors during the treatment, the intercisal angle improved from 125 to 127
degrees.
|
Case report 3
|
|---|
A 10-year-old boy presented for orthodontic treatment (Figures 69–76). There were
no remarkable features in his medical history, although a mouth breathing habit was reported by
the parents. He presented with a Class II skeletal malocclusion characterized by mandibular
retrusion, anterior open bite, severe overjet, and maxillary and mandibular arch length
discrepancies, accompanied by a deficient mandible and high mandibular plane angle with lip
incompetence (Figures 69–71). The
initial panoramic radiographs
revealed that all
permanent teeth were present. Dentally, the patient exhibited a Class II division I malocclusion
with the overjet was measured at 10 mm. A constriction of the maxillary arch resulted in a
V-shaped maxillary arch form, but no posterior crossbite was present. The lower arch exhibited a
late mixed dentition and leeway-space was present (Figure
76). The
naso-labial angle was upright.
The lips and chin were retruded according to the skeletal pattern and an incompetence of the lips
was evident (Figures 77–79, Table 3).
Treatment progress
A rapid palatal expander was used for 12 weeks to widen the maxilla and to obtain a
transverse inter-arch co-ordination. A mandibular `bite-block', worn for 9
months, was placed on the posterior teeth to guarantee vertical control during the expansion
(Figures 80–84). After the RPE was
removed, initial levelling in
both arches was
accomplished with 0.014-inch Ni–Ti archwires on a pre-adjusted edgewire
appliance
(bi-dimensional technique; Figures
85–87). The class correction
was obtained by using
Class II elastics (6oz/3/16) on 0.18 x 0.22-inch rectangular arches, while
the
patient wore a lip bumper in the lower arch for 14 hours daily (Figures 88–92). The
patient's co-operation was excellent and the treatment was completed in 29 months
(Figures 93–100). Retention was
accomplished with maxillary and
mandibular acrylic
retainers.
Results
The patient grew considerably during the 29 months between the serial cephalograms
(Figure
104).
A good result was achieved with a significant improvement in occlusal and skeletal
relationships. After the treatment the facial aesthetics was well balanced and the lips were nicely
related to each other (Figures 93–95). A
normal molar and canine
Class I relationship was
obtained with a reduction of overjet from 10 to 1.mm, and the overbite was corrected to
normal standards.
A significant increase in both the maxillary and mandibular arch widths, and a change in arch
shape were observed (Figures 99–100). The overall vertical
dimension remained relatively
stable, but a small change was obtained on the lower facial height as observed by
N–ANS–Me measurement. The maxillary incisors were uprighted to 2 mm to NA,
while the lower incisors proclinical up to the NB line (Table
3).
|
References
|
|---|
Bench, R. W., Gugino, C. F., Hilgers, J. J., and Schulhof, R. J.
(1978)Bioprogressive therapy, part V, Journal of Clinical
Orthodontics, 12,48
–692.
Haas, A. J. (1970)Palatal expansion: just the
beginning
of dentofacial orthopedics, American Journal of Orthodontics,57
,219
–55.[Medline]
Kirjavainen, M., Kirjavainen, T. and Haavikko, K.
(1977)Changes in dental arch dimensions by use of an orthopedic cervical
headgear in Class II
correction, American Journal of Orthodontics and Dentofacial
Orthopedics, 111
,59
–66.
Ricketts, R. M. (1960)The influence of
orthodontic
treatment on facial growth and development, Angle Orthodontist,30
,103
–33.
Ricketts, R. M., Bench, R. W., Gugino, C. F., Hilgers, J. J. and
Schulhof,
R.
J. (1979) Bioprogressive therapy,Rocky Mountain Orthodontics,
Denver.
Staley, R. N., Stumtz, W. R. and Petersen, L. C.
(1985)A comparison of arch width in adults with normal occlusion and adults
with Class II Division 1
malocclusion, American Journal of Orthodontics,88
,163
–169.[Medline]
Tollaro, I., Baccetti, T., Franchi, L. and Tanasescu, C. D.
(1996)Role of posterior transverse interarch discrepancy in Class II, Division
1
malocclusion during the mixed dentition phase, American Journal of Orthodontics and
Dentofacial Orthopedics, 110,417
–422.[Medline]
Warren, D.W. (1993)Rapid Class II correction
with a
Headgear-Expander, Journal of Clinical Orthodontics,27-9
,503
–507.
Top
Abstract
Introduction
