EARLY TREATMENT SYMPOSIUM

Preadolescent Class II problems:Treat now or wait?William R. Proffit, DDS, PhD, and J. F. Camilla Tulloch, BDS, FDS, DOrthChapel Hill, NC

The timing oftreatment forClass II maloc-

clusion remains a contro-versial clinical issue de-spite the considerablevolume of literature onthis topic over the lastfew years. Clinical deci-sions such as the optimaltime to start treatment areinevitably difficult be-cause of the variability

between patients and the uncertainty about growth andtreatment response. The purpose of clinical research isto provide unbiased evidence so that safe, effective, andefficient procedures can be identified, and ineffective,unsafe, or inefficient practices avoided.

Much of the current debate about early versus latetreatment for Class II malocclusion can be usefullyconsidered in terms of effectiveness and efficiency.Ideally, treatment would be provided when it is mosteffective and most efficient. The debate is not reallywhether Class II malocclusion can be corrected atvarious times in a child’s development; there is ampleevidence from clinical practice that it usually can.Rather, the question should be whether early treatment,which is almost always followed by a second phase oftreatment, provides superior results to conventionaltreatment started in the permanent dentition, and, if itdoes, is there enough additional benefit to justify thealmost inevitable greater burden of treatment for pa-tients, parents, and practitioners?

Several important factors play into the choicesabout the optimal timing of orthodontic treatment forpatients with Class II malocclusion, and these largelyrelate to the uncertainty about growth and treatment

response. The majority of patients with moderate tosevere Class II occlusal problems also have some typeof skeletal imbalance. Thus, early treatment to modifygrowth might allow subsequent treatment to correct thealignment and the occlusion of permanent teeth toproceed more quickly or by simpler methods. Thisargument raises 3 critical issues:

(1) Can jaw growth really be modified, and if so, byhow much, with what predictability, and in whichpatients?

(2) Do different appliances produce different effects?(3) Even if growth can be modified in a controlled

way, what impact would early intervention have onsubsequent orthodontic treatment? Would latertreatment really be simpler and would the treatmentresults be better?

In essence, clinicians would like to be able to advisetheir patients on whether early treatment makes adifference. The purpose of this preliminary report is toprovide some evidence for or against the benefit ofselecting different intervention timings for treatingchildren with Class II malocclusion.

METHODS

In a trial study at the University of North Carolinabetween 1988 and 2000, we selected children withoverjet (OJ) greater than 7 mm who were still in themixed dentition, at least 1 year before their peak heightvelocity, and who had received no prior orthodontictreatment.1 A moderate range of vertical problems wasallowed, but children with extreme vertical dispropor-tions (� 2 standard deviations from published norms)were excluded.2 The trial was conducted in 2 phases.During the first phase, the children were randomlyassigned to treatment starting in the mixed dentition,with either a combination headgear worn alone or afunctional appliance (modified bionator), or to a control(observation only) group in which all treatment wasdelayed until the permanent dentition was established.Records were taken on all the children after they hadbeen followed for 15 months. In the second phase of thetrial, all the children were treated, and the comparison

From the Department of Orthodontics, School of Dentistry, University of NorthCarolina, Chapel Hill.Presented at the International Symposium on Early Orthodontic Treatment,February 8-10, 2002; Phoenix, Ariz.Am J Orthod Dentofacial Orthop 2002;121:560-2Copyright © 2002 by the American Association of Orthodontists.0889-5406/2002/$35.00 � 0 8/1/124684doi:10.1067/mod.2002.124684

560

was made between those who had received earlytreatment and those who had not. This second phase ofthe trial, which is the emphasis of this report, wasdesigned to address whether early treatment to modifygrowth 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, 7-15.5mm). Most of the children (91%) had a bilateral ClassII molar relationship. There was no statistically signif-icant difference between the 3 groups formed by theinitial randomization. Of the 175 children starting thetrial, 166 completed phase 1, and 143 started andcompleted phase 2; 4 children were deemed by theirparents not to need further treatment, and 19 eithermoved from the area or withdrew from the study.

RESULTS

Can you change growth? The results from the firstphase of the trial showed tremendous variability in bothnormal growth and treatment response. Both earlytreatment methods (headgear and modified bionator)did, on average, produce a very similar small meanreduction in jaw relationship when compared with thepatients who were simply observed for an equivalentperiod (15 months). The mechanism of change wasdifferent for the 2 appliances; the headgear groupshowed a restriction in the forward movement of themaxilla when compared with the control and thebionator groups, while the functional appliance groupshowed both an increase in mandibular length com-pared with the control and the headgear groups and anincrease in chin projection. These changes, thoughsmall, were statistically significantly different betweenthe groups. Concentrating on mean changes, however,tends to mask the variability in treatment response. Thedistribution of categories of skeletal change, fromhighly favorable to unfavorable showed that more than75% of the patients in the early treatment groups hadfavorable or highly favorable changes, while only about25% of those in the control group showed similarfavorable changes. The differences in distribution ofresponse categories between the early treatment and thecontrol groups were statistically significant (P �.0001). However, no reliable predictors of the magni-tude or the likelihood of favorable changes have yetbeen determined.3

Does early treatment make a difference? The re-sults of the second phase of the trial focus on 2 types ofoutcome: clinician-centered outcomes, such as changein skeletal jaw relationship or the alignment and theocclusion of the teeth, and more patient- or parent-

centered outcomes, such as the duration of treatment orthe need for extractions or other surgical procedures.4

In Class II treatment, reducing the skeletal jaw dis-crepancy and straightening the profile are generally thetreatment goals. The degree to which parents and patientsconcur with these clinician-centered goals is not clear. Theimpact of early treatment is therefore described in terms ofthe change in skeletal jaw relationship and the proportionof patients with convex profiles at the end of treatment.Skeletal jaw relationship was measured in various ways,including linear, angular, and positional. The results fromeach measurement method concurred. However, only theANB angle is reported here, because this measurement ismost frequently used in the literature to designate askeletal Class II condition.5 There was no differencebetween the groups in the ANB angle either at the start orafter phase 2 of treatment. Although the 2 early treatmentgroups experienced an early reduction in the ANB angleduring phase 1, this initial advantage was not sustainedduring phase 2. Neither was there a difference in theproportion of patients with convex profiles (A-B differ-ence � 7 mm) after phase 2. This should probably not beinterpreted as meaning that early treatment provides onlya transient benefit in skeletal change but, rather, thatconventional orthodontic treatment in the early permanentdentition might be equally effective in correcting theseproblems. The treatment mechanics clinicians use tocorrect a moderate-to-severe skeletal problem in a grow-ing child in the early permanent dentition are likely to bedifferent from those used for patients with only smalldisproportions remaining after early treatment.

The peer assessment rating system (PAR) was used toassess objectively and systematically the alignment andthe occlusion of the teeth in 3 planes.6 There were nodifferences in the quality of the dental occlusion betweenthe children who had early treatment and those who didnot when evaluated as the mean PAR score for each groupat the end of phase 2, in the percentage of childrenachieving excellent, satisfactory, or disappointing occlu-sions, or in the average reduction in PAR score. There wasapproximately the same distribution of successes andfailures with and without early treatment.

Early treatment did not reduce the percentage ofchildren needing extraction of premolars or other teethduring phase 2 treatment, nor did it influence theeventual need for orthognathic surgery.

Treatment time was measured in 2 ways: length oftime 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 treatmentand those who did not. Surprisingly, there was verylittle difference in the time both groups spent wearing

American Journal of Orthodontics and Dentofacial OrthopedicsVolume 121, Number 6

Proffit and Tulloch 561

fixed appliances. Early treatment had only a very smalleffect in reducing the subsequent time in treatment.

DISCUSSION

These data all suggest that early treatment, at leastas carried out in this trial, while quite consistentlyproducing an initial differential growth change depend-ing on the appliance selected, was not, on average, anymore effective than conventional later treatment incorrecting skeletal and dental Class II malocclusion.The severity of the initial condition measured by eitherthe PAR score or the skeletal discrepancy was notcorrelated with improvement in the occlusion or the jawrelationship, or time in fixed appliances. Not only didearly treatment fail to provide any advantage in finaltreatment outcome or simplification of subsequent pro-cedures, but also it took longer. It was no moreeffective and somewhat less efficient.

This should not to be taken to negate the value ofearly treatment for some children. There are manyreasons for recommending early treatment for some,including children with psychological distress, thosewho are particularly accident-prone, and those whoseskeletal maturity is well ahead of their dental develop-ment. Possibly, children who have both vertical andClass II problems might have more of an indication forearly treatment. However, data from our trial cannotaddress this important issue well.

CONCLUSION

The conclusion from this randomized trial is that, inmost instances, there does not seem to be a clearadvantage 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 tobase their treatment decisions.

REFERENCES

1. Tulloch JFC, Phillips C, Koch G, Proffit WR. The effect of earlyintervention on skeletal pattern in Class II malocclusion: arandomized clinical trial. Am J Orthod Dentofacial Orthop 1997;111:391-400.

2. Fields HW, Proffit WR, Nixon WL, Phillips C, Stanek E. Facialpattern differences in long face children and adults. Am J Orthod1984;85:217-23.

3. Tulloch JFC, Proffit WR, Phillips C. Influences on the outcome ofearly 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 atthe turn of the century. Proceedings of the 10th InternationalOrthodontic Studyweek. Nijmegan: Nederlandse Vereniging voorOrthodontische Studie; 2001.

5. Simon LS. A quantitative analysis of the measurements used to defineand describe Class II malocclusion and the effects of treatment ongrowth [thesis]. Chapel Hill: University of North Carolina; 1993.

American Journal of Orthodontics and Dentofacial OrthopedicsJune 2002

562 Proffit and Tulloch