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1. EARLY TREATMENT SYMPOSIUM
Preadolescent Class II problems:
Treat now or wait?
William R. Proffit, DDS, PhD, and J. F. Camilla Tulloch, BDS, FDS, DOrth
Chapel Hill, NC
T
he timing of
treatment for
Class II maloc-
clusion remains a contro-
versial clinical issue de-
spite the considerable
volume of literature on
this topic over the last
few years. Clinical deci-
sions such as the optimal
time to start treatment are
inevitably difficult be-
cause of the variability
between patients and the uncertainty about growth and
treatment response. The purpose of clinical research is
to provide unbiased evidence so that safe, effective, and
efficient procedures can be identified, and ineffective,
unsafe, or inefficient practices avoided.
Much of the current debate about early versus late
treatment for Class II malocclusion can be usefully
considered in terms of effectiveness and efficiency.
Ideally, treatment would be provided when it is most
effective and most efficient. The debate is not really
whether Class II malocclusion can be corrected at
various times in a child’s development; there is ample
evidence from clinical practice that it usually can.
Rather, the question should be whether early treatment,
which is almost always followed by a second phase of
treatment, provides superior results to conventional
treatment started in the permanent dentition, and, if it
does, is there enough additional benefit to justify the
almost inevitable greater burden of treatment for pa-
tients, parents, and practitioners?
Several important factors play into the choices
about the optimal timing of orthodontic treatment for
patients with Class II malocclusion, and these largely
relate to the uncertainty about growth and treatment
response. The majority of patients with moderate to
severe Class II occlusal problems also have some type
of skeletal imbalance. Thus, early treatment to modify
growth might allow subsequent treatment to correct the
alignment and the occlusion of permanent teeth to
proceed more quickly or by simpler methods. This
argument raises 3 critical issues:
(1) Can jaw growth really be modified, and if so, by
how much, with what predictability, and in which
patients?
(2) Do different appliances produce different effects?
(3) Even if growth can be modified in a controlled
way, what impact would early intervention have on
subsequent orthodontic treatment? Would later
treatment really be simpler and would the treatment
results be better?
In essence, clinicians would like to be able to advise
their patients on whether early treatment makes a
difference. The purpose of this preliminary report is to
provide some evidence for or against the benefit of
selecting different intervention timings for treating
children with Class II malocclusion.
METHODS
In a trial study at the University of North Carolina
between 1988 and 2000, we selected children with
overjet (OJ) greater than 7 mm who were still in the
mixed dentition, at least 1 year before their peak height
velocity, and who had received no prior orthodontic
treatment.1
A moderate range of vertical problems was
allowed, but children with extreme vertical dispropor-
tions (Ͼ 2 standard deviations from published norms)
were excluded.2
The trial was conducted in 2 phases.
During the first phase, the children were randomly
assigned to treatment starting in the mixed dentition,
with either a combination headgear worn alone or a
functional appliance (modified bionator), or to a control
(observation only) group in which all treatment was
delayed until the permanent dentition was established.
Records were taken on all the children after they had
been followed for 15 months. In the second phase of the
trial, all the children were treated, and the comparison
From the Department of Orthodontics, School of Dentistry, University of North
Carolina, Chapel Hill.
Presented at the International Symposium on Early Orthodontic Treatment,
February 8-10, 2002; Phoenix, Ariz.
Am J Orthod Dentofacial Orthop 2002;121:560-2
Copyright © 2002 by the American Association of Orthodontists.
0889-5406/2002/$35.00 ϩ 0 8/1/124684
doi:10.1067/mod.2002.124684
560

2. was made between those who had received early
treatment and those who had not. This second phase of
the trial, which is the emphasis of this report, was
designed to address whether early treatment to modify
growth makes a difference in terms of treatment out-
come or treatment procedures.
The sample included more boys than girls (57.8%
vs 42.2%), with a mean age of 9.4 years (range,
7.3-12.6 years) and a mean OJ of 8.4 mm (range, 7-15.5
mm). Most of the children (91%) had a bilateral Class
II molar relationship. There was no statistically signif-
icant difference between the 3 groups formed by the
initial randomization. Of the 175 children starting the
trial, 166 completed phase 1, and 143 started and
completed phase 2; 4 children were deemed by their
parents not to need further treatment, and 19 either
moved from the area or withdrew from the study.
RESULTS
Can you change growth? The results from the first
phase of the trial showed tremendous variability in both
normal growth and treatment response. Both early
treatment methods (headgear and modified bionator)
did, on average, produce a very similar small mean
reduction in jaw relationship when compared with the
patients who were simply observed for an equivalent
period (15 months). The mechanism of change was
different for the 2 appliances; the headgear group
showed a restriction in the forward movement of the
maxilla when compared with the control and the
bionator groups, while the functional appliance group
showed both an increase in mandibular length com-
pared with the control and the headgear groups and an
increase in chin projection. These changes, though
small, were statistically significantly different between
the groups. Concentrating on mean changes, however,
tends to mask the variability in treatment response. The
distribution of categories of skeletal change, from
highly favorable to unfavorable showed that more than
75% of the patients in the early treatment groups had
favorable or highly favorable changes, while only about
25% of those in the control group showed similar
favorable changes. The differences in distribution of
response categories between the early treatment and the
control groups were statistically significant (P Ͻ
.0001). However, no reliable predictors of the magni-
tude or the likelihood of favorable changes have yet
been determined.3
Does early treatment make a difference? The re-
sults of the second phase of the trial focus on 2 types of
outcome: clinician-centered outcomes, such as change
in skeletal jaw relationship or the alignment and the
occlusion of the teeth, and more patient- or parent-
centered outcomes, such as the duration of treatment or
the need for extractions or other surgical procedures.4
In Class II treatment, reducing the skeletal jaw dis-
crepancy and straightening the profile are generally the
treatment goals. The degree to which parents and patients
concur with these clinician-centered goals is not clear. The
impact of early treatment is therefore described in terms of
the change in skeletal jaw relationship and the proportion
of patients with convex profiles at the end of treatment.
Skeletal jaw relationship was measured in various ways,
including linear, angular, and positional. The results from
each measurement method concurred. However, only the
ANB angle is reported here, because this measurement is
most frequently used in the literature to designate a
skeletal Class II condition.5
There was no difference
between the groups in the ANB angle either at the start or
after phase 2 of treatment. Although the 2 early treatment
groups experienced an early reduction in the ANB angle
during phase 1, this initial advantage was not sustained
during phase 2. Neither was there a difference in the
proportion of patients with convex profiles (A-B differ-
ence Ͼ 7 mm) after phase 2. This should probably not be
interpreted as meaning that early treatment provides only
a transient benefit in skeletal change but, rather, that
conventional orthodontic treatment in the early permanent
dentition might be equally effective in correcting these
problems. The treatment mechanics clinicians use to
correct a moderate-to-severe skeletal problem in a grow-
ing child in the early permanent dentition are likely to be
different from those used for patients with only small
disproportions remaining after early treatment.
The peer assessment rating system (PAR) was used to
assess objectively and systematically the alignment and
the occlusion of the teeth in 3 planes.6
There were no
differences in the quality of the dental occlusion between
the children who had early treatment and those who did
not when evaluated as the mean PAR score for each group
at the end of phase 2, in the percentage of children
achieving excellent, satisfactory, or disappointing occlu-
sions, or in the average reduction in PAR score. There was
approximately the same distribution of successes and
failures with and without early treatment.
Early treatment did not reduce the percentage of
children needing extraction of premolars or other teeth
during phase 2 treatment, nor did it influence the
eventual need for orthognathic surgery.
Treatment time was measured in 2 ways: length of
time in phase 2, and time spent wearing fixed appli-
ances. There was tremendous variability in these meas-
urements, both in the children who had early treatment
and those who did not. Surprisingly, there was very
little difference in the time both groups spent wearing
American Journal of Orthodontics and Dentofacial Orthopedics
Volume 121, Number 6
Proffit and Tulloch 561

3. fixed appliances. Early treatment had only a very small
effect in reducing the subsequent time in treatment.
DISCUSSION
These data all suggest that early treatment, at least
as carried out in this trial, while quite consistently
producing an initial differential growth change depend-
ing on the appliance selected, was not, on average, any
more effective than conventional later treatment in
correcting skeletal and dental Class II malocclusion.
The severity of the initial condition measured by either
the PAR score or the skeletal discrepancy was not
correlated with improvement in the occlusion or the jaw
relationship, or time in fixed appliances. Not only did
early treatment fail to provide any advantage in final
treatment outcome or simplification of subsequent pro-
cedures, but also it took longer. It was no more
effective and somewhat less efficient.
This should not to be taken to negate the value of
early treatment for some children. There are many
reasons for recommending early treatment for some,
including children with psychological distress, those
who are particularly accident-prone, and those whose
skeletal maturity is well ahead of their dental develop-
ment. Possibly, children who have both vertical and
Class II problems might have more of an indication for
early treatment. However, data from our trial cannot
address this important issue well.
CONCLUSION
The conclusion from this randomized trial is that, in
most instances, there does not seem to be a clear
advantage for early treatment for Class II malocclusion.
As additional data on phase 2 outcomes become avail-
able from other well-controlled clinical studies, clini-
cians will have more unbiased evidence on which to
base their treatment decisions.
REFERENCES
1. Tulloch JFC, Phillips C, Koch G, Proffit WR. The effect of early
intervention on skeletal pattern in Class II malocclusion: a
randomized clinical trial. Am J Orthod Dentofacial Orthop 1997;
111:391-400.
2. Fields HW, Proffit WR, Nixon WL, Phillips C, Stanek E. Facial
pattern differences in long face children and adults. Am J Orthod
1984;85:217-23.
3. Tulloch JFC, Proffit WR, Phillips C. Influences on the outcome of
early treatment for Class II malocclusion. Am J Orthod Dentofa-
cial Orthop 1997;111:533-42.
4. Tulloch JFC. The timing of treatment for Class II malocclusion.
In: Kuijpers-Jagtman AM, Leunisse M, editors. Orthodontics at
the turn of the century. Proceedings of the 10th International
Orthodontic Studyweek. Nijmegan: Nederlandse Vereniging voor
Orthodontische Studie; 2001.
5. Simon LS. A quantitative analysis of the measurements used to define
and describe Class II malocclusion and the effects of treatment on
growth [thesis]. Chapel Hill: University of North Carolina; 1993.
American Journal of Orthodontics and Dentofacial Orthopedics
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