EARLY ORTHODONTIC TREATMENT: WHAT ARE THE IMPERATIVES?
G. THOMAS KLUEMPER, D.M.D., M.S.,
CYNTHIA S. BEEMAN, D.D.S., PH.D. and
E. PRESTON HICKS, D.D.S., M.S., M.S.D.
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ABSTRACT
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Background. The authors provide a critical review of the issues involved in determining the appropriate timing of orthodontic treatment. Both single- and two-phase treatments are discussed and guidelines are offered to assist in formulating treatment plans.
Overview. In providing orthodontic care for pediatric patients, clinicians often question whether to begin treatment early—during the primary or early-transitional dentition—or wait until all or most of the permanent teeth are present. The authors review the most current literature (from 1991 to 1999), including several recently completed and ongoing randomized clinical trials, to critically evaluate the effectiveness of each approach.
Practical Implications. The controversy surrounding early vs. late orthodontic treatment is often confusing to the dental community. This article reviews both sides of the issue for orthodontic treatment of Class II and III malocclusions, as well as for the management of Class I crowding and problems in the transverse dimension. Early orthodontic treatment is effective and desirable in specific situations. However, the evidence is equally compelling that such an approach is not indicated in many cases for which later, single-phase treatment is more effective. Therefore, clinicians must decide, on a case-by-case basis, when to provide orthodontic treatment. For many patients, delaying treatment until later in their dental and skeletal development may be advisable.
Early, or phase I, orthodontic treatment refers to treatment that precedes the conventional treatment protocol in which brackets and bands are placed on permanent teeth. This early treatment is begun during either the primary or transitional dentition to intercept malocclusions in a manner that will ultimately lead to a better, more stable result than that which would be achieved by starting treatment later. The goal of many clinicians who provide early treatment is to reduce the time and complexity of fixed-appliance therapy. Whether, in fact, early treatment is beneficial in terms of the long-term care of orthodontic patients is controversial.
The questions related to this two-phase method of treatment have led to the need for critical analyses of the effectiveness of such an approach. For example, does early treatment work better than a later, singular phase of orthodontic treatment? Is an early approach worth the extra cost, time and energy involved? Are the outcomes significantly improved over those of a single-phase treatment approach? If some orthodontic problems are better treated early, should all problems be corrected early?
In a recent survey of the 159 Diplomates of the American Board of Orthodontics, participants were asked what they perceived to be the benefits of early treatment.1 The most common responses were as follows:
- – greater ability to modify skeletal growth;
- – improved patient self-esteem and parental satisfaction;
- – better and more stable result;
- – less-extensive therapy is required later;
- – reduced potential for iatrogenic tooth damage such as trauma, root resorption and decalcification.
These responses seem to be supported by the results of a recent study in which orthodontists perceived that subjects who received phase I orthodontic treatment had less complex malocclusions with a lower treatment priority than subjects in an untreated control group.2 We will use these perceptions to evaluate the actual outcomes of phase I treatment, as determined by recent research studies dealing with this issue.
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EARLY TREATMENT OF CLASS II MALOCCLUSION
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Substantial evidence supports the theory that early growth modification therapy can lead to an improvement, if not complete correction, of the Class II malocclusion.3–5 The mechanisms by which the correction is achieved, and whether early correction has advantages over correction during phase II treatment lead to three fundamental questions:
- – Is facial growth altered or is the correction due to dentoalveolar changes?
- – If facial growth is altered, do the changes represent a permanent effect or simply a short-term response that will be negated by subsequent growth?
- – Is the mechanism of change acting on the maxilla, the mandible or both?
Recently, the results of three randomized clinical trials specifically designed to address these important issues were published.3–5 The randomized clinical trial is generally considered to be the gold standard for clinical research. Randomization eliminates allocation bias, and a prospective approach allows for greater control of confounding variables.6
Tulloch and colleagues3 recently published a progress report from a University of North Carolina, or UNC, study of the benefits of two-phase vs. one-phase Class II treatment. In this randomized clinical trial, children with a moderate-to-severe Class II malocclusion were randomly assigned to one of three groups: headgear treatment, bionator therapy or an observational group in which no treatment was administered. The results suggested that treatment with either headgear or bionator can improve the relationship of the jaws in most children (75 percent), although there was substantial individual variation noted in both treatment groups, as well as in the untreated control group. Reliable predictors for a favorable growth response were not identified.
Substantial evidence supports the theory that early growth modification therapy can lead to an improvement of the Class II malocclusion.
The second phase of the UNC study was designed to test whether these changes represented long-term differences. Once the permanent teeth emerged, the subjects were randomly assigned to orthodontic fixed-appliance (phase II) therapy.
At the completion of treatment, the investigators found no significant differences among the three groups in regard to subjects’ skeletal relationships, as determined by their cephalometric measurements. In addition, there were no significant differences in subjects’ occlusions. It appears, then, from the results of this study that, on average, the skeletal changes that occur with early treatment are not sustained. The improvement in jaw relationships seems to represent a period of accelerated growth rather than a permanent change.
Tulloch and colleagues3 also noted that the number of patients who required extractions of permanent teeth was greater in the bionator group than in the headgear or control groups, and that orthognathic surgery was offered more often (although not necessarily accepted) to patients in the control group than to patients in either of the two-phase groups.
These authors concluded that for children with moderate-to-severe Class II malocclusion, early (phase I) treatment followed by conventional orthodontics later on (phase II) does not produce skeletal or occlusal relationships that differ substantially from those produced by phase II treatment alone. Moreover, severity of the problem and total treatment time are not important influences on the final result, while variations in skeletal growth patterns do seem to play an important role.
Ghafari and colleagues4 conducted another randomized clinical trial of the effectiveness of early treatment in the correction of the Class II malocclusion. In this study, conducted at the University of Pennsylvania, or UP, 63 patients with Class II malocclusion who were between the ages of 7 and 13 years were randomly assigned to either a straight-pull headgear group or a Frankel therapy, or FR-II, group.
As a result of treatment, the sagittal discrepancy was reduced in both groups. Similar to the UNC study results, the results of the UP study showed that the headgear correction was due primarily to its effect on the maxilla, while the FR-II had its greatest influence on mandibular position. In regard to the dentition, improvements in molar and canine relationships were greater in the headgear group, while overjet correction was better in the FR-II group, although this difference in overjet correction was not statistically significant. These occlusal differences were probably due in part to the greater influence of the headgear on the posterior dentition and the palatal force exerted on the maxillary incisors by the labial bow of the FR-II.
To address the issue of treatment timing, the investigators further categorized the experimental groups on the basis of emergence or nonemergence of the permanent canines, premolars and permanent second molars. None of the changes mentioned above was influenced by these stages of dental development. As reported by Ghafari and colleagues,4 Class II treatment seems to be just as effective in late childhood as it is at an earlier age.
Keeling and colleagues5 reported findings from a similar randomized clinical trial conducted at the University of Florida. Their data showed that both headgear (cervical or occipital anchorage with acrylic intraoral bite plane) and bionator treatments in preadolescent children can result in short-term skeletal changes. Subjects in both treatment groups demonstrated enhanced mandibular growth compared with subjects in the control group.
One-year follow-up after completion of treatment in the University of Florida study showed that the skeletal changes were stable; however, some of the dental movements relapsed.
We can conclude that both the single-and two-phase approaches are effective in correcting the Class II malocclusion.
On the basis of these three ongoing clinical trials we can conclude that both the single-and two-phase approaches are effective in correcting the Class II malocclusion. This correction is due to both a skeletal and dental change, depending on the particular treatment modality. Moreover, within the skeletal changes, different appliances and therapies seem to exert more influence on one jaw over the other.
These studies do not support the claim that a favorable effect on skeletal growth patterns is limited to two-phase orthodontic treatment. In fact, these and other recent studies suggest that as long as the patient is treated while he or she is still growing, the time at which treatment begins may not make a difference in the success of the Class II correction.7–9 If this is true, we can conclude that a later-stage, single-phase treatment approach is preferable because of the advantages that accompany the reduced treatment time. This conclusion, of course, is made with the primary criterion for success being a better, more stable result. If the definition of success is broadened to include improved self-esteem and reduced susceptibility to dental trauma, then it may be appropriate to begin treatment at an earlier age.
However, the impact of early treatment on psychological development has yet to be substantiated. Certainly, these issues alone can, and do, serve as impetus for early intervention. The reasons for correcting the malocclusion at an early age should be explained to the patient, but early treatment should not be mistakenly referred to as the only way to achieve a high-quality result. Johnston9 has referred to the decision about when to treat as "mortgaging the mandible"; a Class II correction can be achieved now or later. As long as the reasons are clear and supported by sound evidence, such as the data collected in the studies discussed above, the choice of timing comes down to the clinical judgment of the orthodontist in consultation with the patients and families served.
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EARLY CLASS III TREATMENT
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The Class III skeletal pattern is the result of a small and/or posteriorly positioned maxilla, a large and/or prognathic mandible, or a maxilla and mandible that are normal in the sagittal plane of space but underdeveloped in the vertical dimension. Most often, the Class III malocclusion is caused by a combination of two or all three discrepancies. The most common treatment for this problem in the growing patient involves the use of protraction headgear, with or without prior palatal expansion. For patients in whom a skeletal crossbite is present, orthopedic expansion is appropriate. Some clinicians suggest that such expansion also facilitates the anteroposterior response to facemask therapy, but this thesis has not been substantiated and, therefore, this treatment is not advised for this purpose alone.10
The typical protocol in face-mask therapy is the application of approximately 12 ounces of force on the maxilla for 14 hours a day in a forward and slightly downward direction. The orthopedic and orthodontic responses to this force system include forward and downward movement of the maxilla, with concomitant forward and downward movement of the maxillary dentition, downward and backward rotation of the mandible, and retro-clination of the mandibular incisors. All of these changes improve the three skeletal discrepancies contributing to the Class III malocclusion (Figures 1
through 4). The only Class III pattern for which these changes would be contraindicated is one with excessive vertical development.
Orthodontists most often prescribe facemask therapy for patients in the primary to early-transitional dentition, in large part because of the patency of the circummaxillary sutures appropriate to this age.11 Growth modification of this kind is based on the premise that applying tension to these immature sutures is a stimulus for the formation of new bone. The closer the patient is to adolescence, the more interdigitation of the sutures that exists, which results in less skeletal and more dental response to the protraction forces. We believe that the adolescent circummaxillary sutures are amenable to tensile forces, but that the elastic nature of the facemask force system simply is not capable of delivering high-enough force levels to affect these sutures.
In addition to the importance of sutural patency, timing of treatment involving protraction headgear depends, although to a lesser degree, on the developing dentition. Primary or permanent teeth with adequate roots are required for protraction force application. Consequently, the late-transitional dentition presents challenges to facemask therapy, since this stage of dental development may not provide the clinician with an adequate anchor for headgear.
A recent study of Class III treatment supports using face-mask therapy during the primary and early-transitional dentition, although it suggests that treatment at later stages is not without merit. Kapust and colleagues12 determined the effects of facemask therapy combined with palatal expansion in 63 patients ranging in age from 4 to 13 years. The results indicated that when compared with nontreated subjects, patients in the experimental group demonstrated significant skeletal changes, including forward and downward maxillary movement and downward and backward mandibular rotation. Dental changes included extrusion of the maxillary molars and retro-clination of the mandibular incisors. These combined changes led to a significant improvement in the soft-tissue profile. Although a significantly greater correction of the Class III pattern was observed in 4-to 10-year-olds than in 10- to 13-year-olds, the effect of age on treatment response was less than would be commonly expected. These findings suggest that while early treatment may be more effective, face-mask therapy does produce favorable orthopedic and dental changes in older children.
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EARLY TREATMENT OF TRANSVERSE DISCREPANCIES
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Unilateral or bilateral cross-bites are caused by dental or skeletal discrepancies, or a combination of the two. Correction of discrepancies in the transverse plane involves either dental or palatal expansion. The former is accomplished by simple tooth movement and, therefore, generally is best done during phase II treatment. The correction of a skeletal crossbite via palatal expansion involves manipulation of the sutures within and surrounding the maxilla. Consequently, this procedure must precede the ossification of these sutures. Once the palatal suture is fused, correction of a skeletal crossbite usually requires surgical intervention.
Although variation exists among people, ossification of the midpalatal suture is extensive, but not complete, in late adolescence.13 However, in the early stages of skeletal maturation (that is, before the adolescent growth spurt’s peak height velocity), little-to-no midpalatal approximation exists. Therefore, beginning palatal expansion just before the onset of puberty is consistent with the biology of the tissue involved. In addition, no compelling evidence exists to suggest that a clinician is any more successful in achieving palatal expansion at an earlier age, although Spillane and McNamara14 have shown that expansion in the transitional dentition is stable. Consequently, other treatment issues may best determine the timing of palatal expansion.
A child exhibiting a lateral functional shift is a candidate for early orthopedic correction. Such a shift is often the result of compensatory and habitual movement of the mandible to achieve intercuspation in the face of a constricted maxillary arch. In this situation, the mandible approaches centric relation with facial and dental midlines coinciding. However, because of palatal constriction, premature contact occurs, usually in the area of the primary canines, and the mandible shifts to one side to avoid this contact and to achieve centric occlusion. Consequently, the condyles are positioned asymmetrically within their respective fossae and the mandible is positioned off-center, with the lower midline deviated to the shifted side. This gives the appearance of a unilateral crossbite when, in fact, it is bilateral. Left untreated, this condition can lead to asymmetrical growth of the mandible and uneven remodeling of the glenoid fossa.15 This scenario can lead to permanent facial asymmetry, even if the constricted maxillary arch is corrected at a later date.
Maxillary expansion is the indicated treatment for palatal constriction. Increased maxillary width removes the premature contacts, eliminates the mandibular shift and allows the mandible to achieve centric relation with coinciding mid-lines. When this occurs, occlusal symmetry is achieved and symmetrical growth is no longer inhibited. Consequently, a strong argument can be made for early treatment in such cases. Maxillary constriction without a lateral shift does not carry the same urgency and, therefore, can be treated closer to adolescence.
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EARLY TREATMENT OF ARCH-LENGTH DISCREPANCIES
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To determine the need for and appropriate timing of treatment for arch-length discrepancies, clinicians must be knowledgeable about normal arch development. During the period of transition from the primary to permanent dentition, minor incisor crowding is often present in the normally developing dentition (that is, the dentition that will ultimately have enough room for all of the permanent teeth without orthodontic intervention).
Such crowding is often seen after the eruption of the succedaneous mandibular incisors. With the eruption of the permanent mandibular lateral incisors, mild incisor crowding represents a normal stage of development. Continued growth and development relieve the crowding to the extent that there is enough space available for the permanent mandibular canines to erupt. According to Proffit and Fields,16 there are three reasons for this space gain:
- – With normal growth, a slight increase in arch width occurs across the canines. This amounts to about 2 millimeters of space gain and is due, in part, to a labially inclined path of canine eruption. More width is gained in the maxilla than in the mandible, and, on average, it occurs to a greater extent in boys than in girls.
- – As the succedaneous incisors replace their primary counterparts, they flare forward, gaining 1 to 2 mm of arch length.
- – In the mandibular arch, the primate space is located posterior to the primary canines. Consequently, the permanent canines erupt in a more posterior position than their primary counterparts, leaving the gained space of about 1 mm on each side available for the alignment of the incisors.
To determine the need for and appropriate timing of treatment for arch-length discrepancies, clinicians must be knowledgeable about normal arch development.
In contrast to the transitional crowding seen in the mandibular arch, a transitional diastema often exists between the permanent maxillary central incisors. At this stage, a diastema often causes concern for parents because the teeth appear to be erupting into unfavorable positions. However, for most children, this is a natural transitory state that is self-correcting. With the subsequent eruption of the maxillary lateral incisors and canines, a central diastema of 2 mm or less typically closes naturally. Larger diastemata likely will require orthodontic intervention to achieve complete closure. However, if the occlusion is developing normally otherwise and the child is not overly concerned about the space, we recommend that canine eruption be given a chance to reduce the space.
Clinicians also can alleviate crowding of the anterior dentition by using potential posterior space. Unlike the situation for the anterior teeth, the permanent canines and premolars have a combined mesiodistal width that is smaller than the width of the primary teeth they replace. The combined difference is, on average, 2.5 mm for each side in the mandible and 1.5 mm in the maxilla. The extra space that this represents is referred to as the leeway space. If left to nature, this space will be taken up by mesial drifting of the permanent first molars. Orthodontic management of this space, however, can preserve it to relieve crowding of anterior teeth. Such space preservation can be achieved by placing a lingual holding arch or a lip bumper on the lower arch and a transpalatal appliance or headgear on the maxilla (Figures 5 and 6). In his experience, Gianelly17 has found that management of the leeway space alone can resolve the crowding problems in more than 80 percent of orthodontic patients. Optimal timing for this treatment should coincide with exfoliation of the primary second molars, typically in the late-transitional dentition.
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Figure 6. Same mandibular arch shown in Figure 5 after natural transition of posterior dentition. Note the relief of minor crowding due to posterior drift of anterior teeth into leeway space, preserved by the lingual arch.
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Arch width expansion in the absence of a transverse discrepancy is sometimes indicated to increase the arch perimeter, thereby relieving arch-length discrepancies. In general, beginning the expansion in the late-transitional dentition is ideal because it can be followed immediately with placement of fixed appliances to direct the permanent teeth into the newly created space. However, earlier intervention sometimes is indicated. When crowding is severe enough to prevent the natural eruption of certain teeth—for example, the permanent maxillary lateral incisors—then expansion would be indicated at the age of 6 or 7 years. In addition, eruption of teeth into a crowded arch may have occurred, but their malpositioning leads to unfavorable wear patterns. This also would be an indication for early expansion followed by active alignment, rather than for delaying treatment until more of the permanent teeth erupt, which may cause continued harmful wear of the enamel.
In most cases, if expansion is chosen to relieve crowding, it can be delayed until the late-transitional dentition. Common exceptions to this have been described above. In these cases, timing will center on the eruption of the affected teeth. There is no scientific evidence to support the idea that expansion in the primary dentition is more stable than that in the early-to-late transitional dentition.
In cases of severe crowding, extraction of permanent teeth may be desirable. In these cases, a serial extraction plan may be indicated. This protocol calls for the sequenced extraction of specific primary teeth to facilitate the early eruption of the permanent teeth identified for extraction. These are usually the first premolars. In cases of severe crowding, such a plan allows for the second premolars and canines to erupt well within the alveolus rather than ectopically. Once the remaining permanent teeth have erupted, fixed appliances are placed to provide ideal alignment within an arch in which the space discrepancy has been eliminated. Ideally, serial extractions begin in the early-transitional dentition, while the placement of fixed appliances is delayed until the early-permanent dentition.
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SUMMARY
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Early orthodontic treatment is effective and desirable in specific situations. Evidence is equally compelling, however, that such an approach is not indicated in many cases, and delaying treatment until later in dental development may be advised.
In the treatment of patients with Class II malocclusion, correction at an early or late stage is equally beneficial. While this conclusion reflects the statistical comparison of average treatment responses in the studies cited, there were large individual variations within the treatment groups. We recognize that caution is in order when interpreting these mean data. Such large statistical variances suggest the possible existence of significant variables that have not been identified or controlled for in these clinical trials. The immediate effect that early treatment may have on a patient’s self-esteem and susceptibility to dental trauma is not well-understood and is likely to vary from patient to patient. Beginning treatment of Class II discrepancies at an early age has the potential to extend the overall treatment time.
Patients with Class III mal-occlusion stand to benefit significantly from early orthopedic treatment. However, such therapy may produce more favorable changes for older children (aged 11 and 12 years) and adolescents (aged 13 and 14 years) than previously thought.
Palatal expansion appears to be effective and stable at any time before late adolescence, a stage of development when ossification of the midpalatal suture begins. Consequently, the timing of expansion may be better determined by the specific needs of each patient. A functional shift resulting from a crossbite is optimally corrected early so that asymmetrical growth of the mandible can be reduced or even prevented. Expansion for the relief of crowding is best timed on the basis of the specific nature of the crowding. No compelling evidence exists to suggest that arch expansion in the primary dentition will produce a more stable result than that achieved at a later time.
Treatment of arch-length discrepancies depends on the nature of the crowding. Natural arch development has the potential to correct early mild incisor crowding. Management of the leeway space will resolve a majority of cases of crowding. This approach is best accomplished in the transitional to late-transitional dentition. Severe crowding may warrant the extraction of permanent teeth. A serial extraction protocol may be desirable and the extraction sequence for such an approach begins in the early-transitional dentition, while the appliance phase occurs in the early-permanent dentition.
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FOOTNOTES
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Dr. Kluemper is an associate professor, University of Kentucky, College of Dentistry, Orthodontic Graduate Program, Room D-406 UKMC, 800 Rose Street, Lexington, Ky. 40536-0297. Address reprint requests to Dr. Kluemper.
Dr. Beeman is an associate professor, University of Kentucky, College of Dentistry, Orthodontic Graduate Program, Lexington.
Dr. Hicks is an associate professor, University of Kentucky, College of Dentistry, Orthodontic Graduate Program, Lexington.
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REFERENCES
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- King GJ, Wheeler TT, McGorray SP, Aiosa LS, Bloom RM, Taylor MG. Orthodontists’ perceptions of the impact of phase 1 treatment for Class II malocclusion on phase 2 needs. J Dent Res 1999;78:1745–53.[Abstract/Free Full Text]
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- Keeling SD, Wheeler TT, King GJ, et al. Anteroposterior skeletal and dental changes after early Class II treatment with bionators and headgear. Am J Orthod Dentofacial Orthop 1998;113(1):40–50.[Medline]
- Semb G, Roberts CT, Shaw WC. The scope and limitations of single center research in cleft lip and palate. In: Vig KW, Vig PS, eds. Clinical research as the basis of clinical practice. Ann Arbor, Mich.: Center for Human Growth and Development, the University of Michigan; 1991:109–23.
- Johnston LE Jr. Growth and the Class II patient: rendering unto Caesar. Semin Orthod 1998;4(1):59–62.[Medline]
- Livieratos FA, Johnston LE Jr. A comparison of one-stage and two-stage nonextraction alternatives in matched Class II samples. Am J Orthod Dentofacial Orthop 1992;108:118–31.
- Johnston LE Jr. Functional appliances: a mortgage on mandibular position. Aust Orthod J 1996;14(3):154–7.[Medline]
- Proffit WR, Fields HW. Orthodontic treatment planning: limitations, controversies and special problems. In: Contemporary orthodontics. 3rd ed. St. Louis: Mosby; 2000:271.
- Proffit WR, Fields HW. Skeletal problems. In: Contemporary orthodontics. 3rd ed. St. Louis: Mosby; 2000: 257, 508–15.
- Kapust AJ, Sinclair PM, Turley PK. Cephalometric effects of face mask/expansion therapy in Class III children: a comparison of three age groups. Am J Orthod Dentofacial Orthop 1998;113:204–12.[Medline]
- Revelo B, Fishman LS. Maturational evaluation of ossification of the midpalatal suture. Am J Orthod Dentofacial Orthop 1994;105:288–92.[Medline]
- Spillane LM, McNamara JA Jr. Maxillary adaptation to expansion in the mixed dentition. Semin Orthod 1995;1(3):76–87.
- Pirttiniemi P, Kantomaa T, Lahtela P. Relationship between craniofacial and condyle path asymmetry in unilateral cross-bite patients. Eur J Orthod 1990;12:408–13.[Abstract/Free Full Text]
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- Gianelly A. Leeway space and the resolution of crowding in the mixed dentition. Semin Orthod 1995;1:188–94.[Medline]
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ABSTRACT
EARLY TREATMENT OF CLASS...
