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ORTHODONTICS: More Than Just Pretty Smiles

February 1, 2000
by S. Jay Bowman, DMD, MSD


It is an easily observable and undeniable fact that the sun rises in the East and sets in the West. Yet many will choose not to believe in phenomena that seems as obvious. Indeed, if the discussion happens to involve professional matters, many are eager to ignore the evidence of their senses, casually suspend disbelief, and accept anecdotal evidence or case reports as fact. This same situation existed in the rise of pseudoscience at the turn of our last century when theories were often presented without substance. The present review is a summary of facial esthetics in terms of research, ambient realities, and salesmanship.

THE ROLE OF FACIAL ESTHETICS IN ORTHODONTICS

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In contemporary discussions of facial esthetics, orthodontics commonly is cast as a whipping boy, on the lecture circuit, in the literature, and occasionally in the courtroom. Self-professed experts on facial esthetics, many with proprietary interests, are numerous; however until recently, there has been little support for any particular esthetic hypothesis. Given the current state of the art, who should serve as the “fashion police” for facial esthetics: the orthodontists, the general dentists or the patients themselves?

The specialty of orthodontics has a long history of concern for facial form and appearance. In the late 1800s, the father of modern orthodontics, Dr. Edward Angle, a devout non-extractionist, saw the bust of Apollo Belevedre (Fig. 1) as the epitome of facial beauty and the gold standard that guided his treatment. Interestingly enough, Elvis Presley appears to be the only contemporary popular icon exhibiting a similar profile. Indeed, if we were to critique this sort of profile in light of the current non-extraction-at-all-costs climate, some might say that Apollo and “the King” had had an unfortunate encounter with an “extraction orthodontist.”

The fear of the “dished-in” profile, said commonly to result from the extraction of premolar teeth, is derived largely from a few isolated lawsuits in the United States and carefully selected reports of unfavorable results. Unfortunately, the fear of the allegation that traditional orthodontics regularly “flatten” facial profiles and produce TMD have significantly altered today’s orthodontic treatment plans. Extraction rates have decreased, despite the absence of a rational theoretical basis or support from the refereed scientific literature. In the process, increasing numbers of orthodontists have eagerly assayed all manner of treatment methods designed to avoid premolar extractions. In many instances, these efforts appear designed to prevent lost referrals or to prevent a possible courtroom encounter, rather than to avoid some proven defect in conventional treatments.

Unfortunately, most of the alternatives to extraction (e.g. arch expansion or development, “flaring,” or bite jumping, etc.) have more in common with orthodontics of the 1800s than what we might expect to see in the newly-arrived 21st century. Many, if not all, of these elderly treatment methods were discarded decades ago by insightful orthodontists (e.g., Tweed, Begg, Strang, Nance, and Case) for just cause: instability, poor facial esthetics, periodontal effects, etc. More to the point, orthodontists long ago challenged Angle’s “arch development” concepts and began to extract to improve poor facial esthetics and to avoid the creation of bimaxillary protrusion. It seems that many orthodontists have forgotten our specialty’s history lessons and thus will be forced to repeat them.

DOES EXTRACTION HARM FACIAL APPEARANCE?

The University of Iowa enlisted the assistance of 39 lay persons to evaluate a sample of 91 extraction and nonextraction patients. Both types of orthodontic treatment, extraction and nonextraction, were perceived to have had produced a favorable impact on facial appearance. Each patient’s treatment had been selected on the basis of specific diagnostic criteria that sometimes argued for extraction and at others, nonextraction. Under these conditions, both treatments produced beneficial esthetic changes.

According to commonly accepted criteria, premolar extractions may sometime be a necessity, especially if reduction in protrusion is a treatment goal. In an assessment of the profiles of 40 pre-adolescent patients, based on the Steiner, Merrifield, and Ricketts cephalometric analyses, it has been suggested that 50% might benefit from some profile reduction. The necessary lingual incisor movement, however, requires space of the amount commonly achieved by extraction. The proclination associated with expansion strategies would obviously be inappropriate if profile improvement is desired by patient and practitioner.

Washington University investigators examined 160 premolar extraction orthodontic cases. On the basis of soft tissue measurements, it was concluded that 90% of the facial profiles were improved by extraction treatment or at least left unchanged. Similar results were reported at the University of Murcia, Spain. One hundred and ninety-eight nonextraction patients were compared with the Washington University extraction sample. Both types of treatment tended to produce similar facial results. In other words, if based on sound diagnostic criteria, extraction was not found to be detrimental to facial esthetics. This might be expected, given that normal facial growth often produces more profound effects on the profile than does the relatively brief phase of orthodontic treatment.

If extraction treatment regularly produces negative facial changes, this impact should be obvious to experts in facial esthetics. Researchers at the University of Mississippi compared three randomly-chosen samples of 15 extraction, nonextraction, and untreated subjects. Forty general practitioners evaluated the 45 post-treatment facial profiles presented in random order. The observers could identify correctly the patients who had orthodontic treatment 52% of the time. In identifying the extraction treatments, the dentists had an accuracy of 49%. Orthodontic specialists fared little better – 55% and 52% correct for patients having had any orthodontic treatment and the extraction patients, respectively. In other words, a coin toss would have been about as good.

Interestingly enough, a subset of general dentists who emphasized orthodontics in their practices were more likely to identify patients erroneously as having had extractions if they exhibited “flat” facial profiles (e.g., Apollo and Elvis). Misidentification by this group was significantly higher (P<0.03) than the other practitioners tested. In the end, presumed experts in facial esthetics of many stripes are unable to perceive any systematic detrimental effects from orthodontics, especially treatment involving bicuspid extractions.

FACIAL ESTHETICS AS VIEWED BY THE END-USER: THE PATIENT

Given the well-documented trend toward nonextraction treatment, dental professionals and lay persons may have come to view facial and smile esthetics differently. The general public appears to find esthetically appealing a range of profiles that run from flat to full, for example, Jackie Onassis, Lady Diana, Chelsea Clinton, Mick Jagger. Perhaps dentists have been sensitized to features that may not be of significance to the general public. Parents of orthodontic patients, for instance, are more accepting of untreated facial profiles. Although Class II and III profiles are rated as less pleasant than Class I profiles, patients were also less critical than professionals, a finding that emphasizes the need to involve the patient in the treatment planning process.

Oynick asked panels of observers to evaluate the treatment results for 50 Class II, Division 1 extraction and non-extraction patients. The pre and post-treatment profiles were shown to laypersons (50 adolescents, 50 adults) and to 10 orthodontic instructors. Approximately 62% of the extraction profiles and 50% of the nonextraction profiles were thought to have been improved by treatment. A subsequent evaluation of 120 Class I and II extraction and nonextraction cases by two panels, 42 denti
sts and 48 laypersons, produced similar results. In this instance, 63% of extraction, but only 27% of nonextraction profiles were believed to have benefited from treatment. The results from these two studies imply that both the public and dental practitioners see a positive impact from extraction treatment for those kinds of patients who are crowded and/or protrusive.

Workers at Saint Louis University have published a series of papers detailing a long-term comparison of extraction and nonextraction treatments. Patients were recalled an average of 14 years after treatment and were asked to examine randomly -ordered tracings of their pre- and post-treatment profiles and to choose the profile they found more attractive. Only half of the nonextraction patients thought that treatment had improved their profile, whereas 58% of the extraction patients believed the same (the extraction cases also tended to be more stable long-term). Although these success rates are only a little better for the extraction treatment, the point here is that extraction clearly did not “dish in” the profiles on a routine basis as posited by the so-called “functional orthodontists.”

When “clear-cut” extraction and nonextraction patients (patients at either ends of the spectrum) were compared, the nonextraction patients were those found to exhibit the “flatter” profiles (Fig. 2).The “clear cut” extraction cases often presented with a chief complaint of significant protrusion that they wished to have reduced. Thus, it was the extraction patient’s profiles that were fuller after treatment. Comparable findings were also reported by James in an evaluation of 170 consecutively-treated patients and by investigators at the University of Iowa in an evaluation of 91 patients.

A similar comparative extraction/nonextraction study was repeated at the University of Michigan with a sample of African American ex-patients. The study, too, noted many distinct benefits of extraction as a treatment for bimaxillary protrusion. These findings were supported by research from Caplan and Shivapuja, who concluded that extraction will result in an improvement in those patients “desiring a less protrusive profile.” It is important to note that African Americans appear to prefer flatter profiles but not as retrusive as those preferred by white patients. In the end, however, only premolar extraction had any marked capacity to produce a reduction in lip protrusion and, hence, a perception of profile improvement for Caucasians and African-Americans who suffer from bimaxillary protrusion.

Panels of laypersons and dental practitioners evaluated the pre- and post-treatment profiles of patients who had either extraction or nonextraction treatment. The impact of bicuspid extraction was shown to be a highly significant function of initial protrusion of the facial profile. Specifically, both panels of evaluators saw extraction as being preferable when the pre-treatment lower lip is more protrusive than 3-4 mm behind the Ricketts’ E-Plane (the line from the tip of the nose to the most anterior prominence of the chin) for whites and 2-4 mm in front of the E-Plane for blacks.

A significant finding from these various reports is that extraction treatment, on average, produce only about a 2 mm decrease in lip protrusion. Although a 2 mm reduction is a clinically discernible change, it hardly amounts to “dishing in” the profile. Indeed, it commonly is a welcome change that the patients, themselves, seek when they present for treatment.

ARE THERE “EXTRACTION” PROFILES?

Recently, Boley posed an interesting question: is there really a profile that is pathognomonic of bicuspid extraction? To address this question, he tested “knowledgeable” orthodontists to determine their ability to ascertain the method of treatment utilized (extraction or nonextraction) simply by examining the patient’s post-treatment smile and profile. Two hundred practitioners were shown 100 finished cases, half extraction and half non-extraction, including 50 color slides of smiling faces and 50 black-and-white profile and front views. The orthodontists were correct only 52% of the time when they evaluated the smiles and only 44% of the time when they were shown facial profiles. Again, they could have done about as well simply by flipping a coin.

It is perhaps significant that, during his treatment of these patients, Boley deliberately maintained arch form and intercanine width. In other words, there was no expansion or “arch development.” As seen in studies at Saint Louis University, the University of Stellenbosch, Republic of South Africa, the University of Tennessee, and the University of Toronto, nonexpanded cases seem to demonstrate more post-retention stability.

WHAT IS THE “BUTCHER’S BILL” FOR PREMOLAR EXTRACTION?

On average, the major effect of first premolar extraction orthodontics appears to be about 2 mm reduction of lip protrusion. Thus, if the face starts out flat, the increased flattening that occurs with normal growth, combined with that produced by the extraction, could then produce a less-than-ideal result. In most instances, over-flattening is a by-product of faulty diagnosis and treatment planning, not a failure to rely solely on nonextraction treatment. In the end, no treatment is so good that it cannot be misused and misapplied.

Practitioners who embrace non-extraction-at-all-costs strategies fail to recognize (or conveniently ignore) that once crowding and/or protrusion are resolved, posterior teeth may simply be moved mesially to close residual extraction space rather than further retracting the anterior dentition. This option, in effect, can preserve the desired facial profile. Moreover, it is useful to point out that there are many kinds and combinations of extractions (e.g. four first premolars, upper firsts and lower seconds, upper second molars, upper and lower second molars, lower incisor, etc.), all of which have different impact on the profile. Accordingly, the front teeth in an extraction case need not undergo the over-retraction trumpeted in the anecdotal reports that inhabit the non-refereed literature.

“FUNCTIONAL ORTHODONTICS” AND THE SEARCH FOR NONEXTRACTION ALTERNATIVES

Recently a series of techniques have been promoted as alternatives to premolar extraction, such as early, functional “appliance treatment,” “arch development” and “multi-phase treatment.” It is easy to make florid claims about these non-extraction techniques, however, it is a bit more of a challenge to produce supporting data.

Although it is possible that functional appliances may alter facial growth, the magnitude of such change appears clinically insignificant and entirely comparable to that produced by more traditional methods. In an evaluation of one and two-stage (functional/fixed) Class II treatments, investigators at the University of Michigan found that both treatments produced skeletal facial changes that left the patients indistinguishable at the end of treatment. In contrast to the beliefs of the functional orthodontists, an early phase of functional appliance treatment appears to provide no unique benefits. As stated succinctly by Paquette et al., “Given that many of the stated goals and effects of functional orthodontics seemed to be based more on wishful thinking than on real-world data, this outcome should come as no surprise.”

The concept of “arch development” to avoid extractions also fails to impress, given the numerous reports of frank instability and the potential for producing untoward periodontal effects. These reports are especially significant, given the existence of more conservative space management alternatives to reduce the percentage of extractions.

It has been reported that at least 75% of minor crowded cases can be treated non-extraction, without expansion, and with superior long-term stability by proper management of leeway space. Significantly, to qualify as a substitute for the 6 mm of space in each quadrant produced by premolar extraction “arch development” would require 12 mm of stable expansion, an amount that is an order of magnitude larger than anythi
ng that can be inferred from the literature.

SUMMARY

A review of the refereed literature provides little support for the viewpoint that bicuspid extraction has a routinely negative impact on facial esthetics and the functional health of the muscles and joints.

Unfortunately, the rules of evidence are often conveniently ignored in today’s orthodontic marketplace. Given a lack of support in the refereed literature, it may be argued that the groundswell of enthusiasm for nonextraction treatment is a threat to the public’s best interests. Consequently, it has been proposed that the patient who presents with crowding and protrusion may be most at risk of a poor result at the hands of some type of ineffective nonextraction treatment (Fig. 3a, b). I would maintain that the extraction decision should not be a political one, but rather should be designed to provide the benefits of esthetics, function, and stability in as conservative and timely a manner as possible.

If one believes that the elimination of extraction is a goal that is more important than addressing the patient’s chief complaints concerning protrusion and if one is unconcerned with the possibility of pushing roots through cortical plates or poor long-term stability, one can elect to treat all patients non-extraction. However, those who believe in avoiding extraction at all costs, should give thought to the possibility that their only ethical option in many crowded and protruded cases would be either to refer the patient for a second opinion or to render no treatment at all. In this argument, Johnston has noted:

The take-home message here is not that nonextraction is bad or that extraction is universally good, but that extraction is a really good treatment in the kinds of faces that appear to need extraction (i.e., crowding and protrusion)… Orthodontists are not condemning patients to overly flat faces by extracting.

In conclusion, skepticism is as important to the selection of treatment methods as it is in weighing the merits of a new bracket or a new practice location. As scientists we should be swayed only by evidence, not by self-serving promotion of untested treatment modalities. The “facts” as inferred from uncontrolled experience may not represent the truth. As Rushing et al. have counseled, “when something new comes along ask, ‘what’s the catch?’ and be persuaded by evidence alone, rather than the strong unsubstantiated claims of individuals who are in a position to influence us.” Failing this, the patient pays a heavy price for our willingness to select treatments without reference either to logic or to evidence.

r. Bowman maintains a private practice in orthodontics in Portage, MI.

Thanks to Dr. Lysle E. Johnston, Jr., the Robert W. Browne Chairman of the Department of Orthodontics and Pediatric Dentistry at the University of Michigan, Ann Arbor for his editorial assistance in the preparation of this manuscript.

References available from Oral Health upon request.

Oral Health welcomes this original article.


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1 Comment » for ORTHODONTICS: More Than Just Pretty Smiles
  1. Vivian says:

    While this is a robust argument against the sweeping anti-extraction stance, a gap, in my opinion, is rating changes to facial esthetics from the *front* view, in addition to the profile. While extractions can be an obvious choice for improving protrusive facial profiles, the consequence of extractions on the facial esthetics from the front is, in my opinion, more important and less predictable. Personally, if I were put in a position where improving my facial profile came at the price of compromising my frontal facial esthetics, I wouldn’t think it was worth it. That is not to say that extractions surely do or do not harm or improve frontal facial esthetics, but just to say that the argument presented in this paper feels incomplete without confirming that piece.

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