Treatment response as an aid in diagnosis and treatment planning James Philadelphia,
1. Ackerman, Pa.,
ith the advent of diagnostic schemes based on cephalometrics and the development of complex mechanotherapies, the simple objectives of orthodontic treatment have become somewhat blurred. Before planning treatment, it is necessary to have a clear definition of the fundamental goals of orthodontics. The objective of orthodontic treatment is to establish optimal proximal and occlusal contact of the teeth within the framework of acceptable facial esthetics, normal function, and reasonable stability. In defining the object.ives of orthodontic treatment, one cannot use the term ideal in regard to proximal and occlusal contact, esthetics, function, and stability. Aside from the classic objection that the ideal rarely exists in nature, there is a more logical reason for using the terms optimal, acceptable, normal, and reasonable in defining our objectives of treatment. The dogmas which imply that functional stability and esthetics “go together like a horse and carriage” are clearly not true. It is possible to achieve good facial esthetics without stability of the teeth, and one can also create a stable result that is not facially esthetic. The relationship is more like “love and marriage”-you can have one without the other. In an attempt to achieve a stable dentition, extraction of teeth may cause less favorable proximal contacts in terms of the “tightness” and “fit” of the contact areas. For example, if it is necessary to extract mandibular second premolars, a marginal ridge height discrepancy between the mandibular first premolar and the mandibular first molar is unavoidable. Obviously, the fundamental objectives of treatment are not always compatible if one insists on a definition that uses the concept of the ideal. Edward Angle’s1 term balance is still perhaps the best word to describe *Associate Pennsylvania **Associate Kentucky
Professor and Chairman, School of Dental Medicine. Professor and Chairman, College of Dentistry.
good clinical orthodontics-striking a balance between optimal proximal and occlusal contact of the teeth, acceptable facial esthetics, normal function, and reasonable stability. Proper classification (systematic description) and diagnosis are prerequisites for determining the nature of an orthodontic problem.” Once the nature of the problem has been determined, the treatment plan defines the steps necessary to achieve a balance of the objectives of treatment. A number of orthodontic diagnostic systems which project a rigid treatment plan from limited cephalometric considerations have been proposed. These systems succeed for the majority of patients and fail for others. Their difficulty is that of the weather forecasts of years past which said flatly: “rain” or “clear.” NO allowance for uncertainty is made, and a definitive treatment plan is called for immediately. There are several sources of uncertainty in orthodontic treatment plans. A major dit%culty is that the cause of a malocclusion is rarely known; as long as this is true, there must be some uncertainty in the treatment plan for correction of the problem. An orthodontic treatment plan is quite likely to be the same, whether the malocclusion is due to genetic influence on jaw morphology or to neuromuscular influences on tooth position, but the treatment response may not be at all the same., Also, the mechanotherapy required to achieve the goals of orthodontic treatment for adults may be considered against a background of unchanging jaw relationships, whereas in growing children the orthodontist must consider the changes that will occur as a result of growth as well as those that are due to treatment. Growth prediction introduces another uncertainty into the diagnostic procedure. Therapeutic
One way to deal with diagnostic uncertainty is to use the treatment response as another diagnostic criterion. This procedure was once advocated in medicine and was called “therapeutic diagnosis.” Therapeutic diagnosis may be defined as a procedure in which an initial diagnosis is made, in the face of some uncertainty, as to the nature of the problem. An initial stage of specifically directed treatment is based on this diagnosis, and the response to this treatment is used to confirm or reject the original diagnosis. For example, an anterior open-bite may be diagnosed as being due to thumb-sucking, and treatment to correct the sucking habit may be started on this basis. If the open-bite corrects itself, the diagnosis is supported. If it persists, the diagnosis will have to be modified, perhaps to include tongue-thrusting. If the open-bite corrects itself after tongue-thrust therapy, this diagnosis is confirmed. If it does not, other factors will have to be considered. In fact, all interceptive procedures in orthodontics are really exercises in therapeutic diagnosis. With the use of tongue-guard appliances, lip bumpers, etc., if the deformity resolves, the indictment of a habit as the cause is confirmed. If the malocclusion persists, then a new hypothesis or diagnosis must be formulated and a new treatment plan established. The use of therapeutic diagnosis implies that the cause of the problem is not known. For this reason, there has been a concerted effort to get away from thera-
peutie diagnosis in medicine. As we learn more about the etiology of malocclusion, we should also strive to perfect our diagnostic abilities in orthodontics. On the other hand, it is important to recognize that a diagnosis which does not include the cause of the problem, as many orthodontic diagnoses do not, is incomplete and leaves room for error. Therapeutic diagnosis is not a substitute for established diagnostic procedures; nor should it become a cover for fuzzy thinking in diagnosis. Where uncertainty exists despite a careful diagnostic evaluation, however, there is danger in formulating a rigid treatment plan. Systematic evaluation of the initial response to orthodontic treatment can help a great deal in making the difficult diagnostic and treatment-planning decisions, especially as concerns the basic question of extraction or nonextraction. Borderline cases, in which the treatment response should be considered b’efore one decides to extract, are more common than many diagnostic systems indicate. It is strength, not weakness, to recognize true uncertainty. To extract
To satisfy the criteria “acceptable esthetics and reasonable stability,” one frequently must consider extracting teeth. In 1907 Calvin Case3 observed that “no matter how irregular the teeth, however bunched, malaligned or malposed, they could always be placed in their respective places in the arches and in normal occlusion; therefore so far as the relations of the teeth to each other are concerned no dental malposition should be taken as a basis for extraction. The only excuse then for the extraction of saveable teeth must be that it is inexpedient or impossible to co’rrect their positions in that way without producing facial protrusion.” The only thing that we would currently add to Case’s dictum is that, in some cases, aligning malposed teeth without extraction might markedly affect the stability of the denture. Unfortunately, we have learned that in as few as 50 per cent of our cases can we say this with assurance (when compared with the stability of the same cases treated with extraction). If we accept esthetics and stability as the valid criteria for extraction in orthodontics, how well ca.n we determine a priori in a child what the face will look like later on in adulthood and what the new functional environment will be after treatment? Part of the answer was pointed out by Tweed4 in 1945, although his interpretation was incomplete. He found that a group of cases that he had treated without extractions showed a great tendency toward collapse. Since these cases had been expanded during treatment, he correctly reasoned that in those cases there was a greater tendency toward contraction of the arches than toward slight growth (expansion). Under the circumstances, he removed teeth in these same cases and closed spaces in a situation in which he had already therapeutically determined that extraction rather than expansion was indicated. In these same cases Tweed also therapeutically determined that the forward expansion of the dental arches had harmed the patients’ profiles. After retreatment with extraction, according to Tweed, these patients’ profiles were much
Can one always make this extraction decision on an a priori basis?In how many casesin which teeth have been extracted has the profile appeared
less pleasing after treatment? Can one always predict what the profile would look like if one did not extract teeth7 In how many mixed-dentition cases have orthodontists performed serial extractions, only to find later that sufficient space had developed for all of the permanent teeth? In orthodontics we have tended to be extreme in our views regarding extraction, At one time it wils a sin to extract in any case, and later nearly all irregularities became extraction cases. For a number of years orthodontists considered that there were only a few “borderline” cases in which a decision to extract or not to extract was somewhat difficult. It is rather unsettling that the so-called “borderline” category probably encompasses more cases than we ever suspected. The truth is that there are few malocclusions which we can say with absolute assurance are nonextraction cases on the basis of predicted adult facial appearance and denture stability. Those which we can say suite absolutely are extraction cases on the same basis are also few. Is not the ultimate facial appearance affected by the growth of several structures (soft tissue, nose, chin) which, at this time, we cannot govern or predict! Is it not also true that stability of the denture depends on factors that we know woefully little about and have little control over? If we do not know the cause of a malocclusion, unless we remove the etiologic factors by chance, there is reason to expect physiologic recovery.5 Indeed, the dimension of diagnosis that is most related to postretention stability is the determination of the cause of the malocclusion. Many since Wallace6 have contended that the growth of the jaws is dependent on the development of the musculature. This concept reaches its fullest interpretation in the functional matrix theory of Moss.’ Yet others contend that hard tissues contain primary growth centers8 We merely point out that the control factors for skeletal and soft-tissue growth are not yet known9 It is no wonder that growth prediction is uncertain when the underlying mechanisms remain so unclear. Growth
Orthodontic diagnosis and treatment planning for growing children must involve growth prediction. This is obviously true in the treatment of skeletal problems, where growth changes are necessary to obtain an optimal treatment result. Most growth-prediction methods emphasize hard-tissue changes. Growth responses are predictable within general limits, but precise prediction of amount, and direction of skeletal growth is beyond our present ability. Variation around the averages on which predictions are based can lead to significant prediction errors. Even when skeletal jaw relationships are not a problem, growth changes at a number of sites affect facial esthetics. Examples of these are growth of the nose, growth related to the chin, and eruption of incisors in an anteroposterior direction. Prediction of soft-tissue changes in the integumental profile, particularly the nose, is difficult and likely to be inaccurate.
In certain casesin which the prediction of growth is known to be difficult, if
J. Orthodont. May 1970
not impossible, as in cases of early Class III malocclusion, it does not surprise or even greatly distress an orthodontist when a persistent Class III tendency recurs years after a case has been “completed.” In those eases it is expected. Yet if recovery (relapse) takes place in another, apparently simpler, kind of malocclusion, the orthodontist is terribly puzzled and annoyed. There are two approaches to orthodontic treatment of skeletal malocclusion. One approach is to attempt to correct the malocclusion at its source by altering the jaw relationship. The other is to camouflage the skeletal discrepancy by moving the teeth into proper occlusal relationships despite the improper jaw relationships. Optimally, an attempt should be made to treat the problem specifically. That is, in skeletal sagittovertical (Class II, Division 1) problems, where there is an anteroposterior discrepancy, one should attempt to “harness” or alter the direction of growth through orthodontic treatment. The only way to ascertain whether it is possible to change the direction of growth in an individual, or whether the patient’s pattern of growth is favorable or unfavorable, is to test the response to treatment. This can be done, of course, with an initial period of headgear or activator treatment. If the response is favorable, one can carry out the rest of the original treatment plan, which may or may not involve full banded treatment. If there is no improvement in jaw relationship, then some compromise of the positions of the teeth within the skeletal framework will have to be made. Frequently, in poorly responding anteroposterior dysplasias, one of the necessary compromises is to extract teeth in order to est,ablish Angle Class I anteroposterior relationships of the teeth. This is particularly likely if there is a Class II neuromuscular pattern accompanying the Class II skeletal problem. The
If one is in doubt about a borderline case, evaluation of response to treatment can begin with the very first phase of treatment. While applying separators in a “crowded” case, one can determine whether all of the contacts are tight. Do most of the separators stay in, or do they fall out in a few days because of sufficient space between the teeth? How sore do the teeth get from the separators? When one fits the bands, how difficult is it to seat all of the bands? When one is working in the patient’s mouth, how tight is the labial and buccal musculature? Does the tongue protrude over the teeth? Do the preformed bands demonstrate significant tooth-size discrepancies between the right and left sides? During the seating of bands, how hard can the patient bite? At the next visit one can check the patient’s oral hygiene. One can also observe whether the patient deformed the arch wires and whether he is a grinder or clencher. This can often be determined from wear facets on the lingual surfaces of the maxillary anterior bands. All these factors are likely to influence the course of treatment. From this frame of reference, much of orthodontic treatment is based on a type of therapeutic diagnosis. If a case is treated successfully (occlusally and facially) without extractions and remains stable, we assume that a correct decision was made and that some of the causes of the problem were also elimi-
response, diagnosis, and treatment
nated. If, on the other hand, nonextraction treatment proceeds with difficulty, adversely affecting facial esthetics or indicating the prospect of an unstable denture, we can then assume that extraction might alleviate the problem. When extraction cases are selected on this basis, the results are more consistently successful. It is no surprise that in these cases the residual extraction spaces close very rapidly after treatment and that the facial esthetics are dramatically improved. It is impractical to perform a therapeutic diagnosis on every orthodontic case. First of all, there are many eases in which the extraction decision is clear from the start (for example, cases of bimaxillary dentoalveolar protrusion with crowding). Second, if therapeutic diagnosis were carried to an extreme, the increase in treatment time in many cases would make the approach unrealistic. Usually the final decision in a therapeutic diagnosis can be made within the first 6 months of treatment. The increase in treatment time is minimal if an extraction decision is made after the first few months, since the first phases of treatment in extraction and nonextraction cases involve the same basic elements of alignment and leveling. Assessment of the patient’s cooperation with regard to wearing of appliances and oral hygiene should not be minimized. Since our treatment plans in orthodontics always call for some type of therapy that requires the patient’s diligence in wearing appliances, this is another factor that can be tested only by instituting treatment. If oral hygiene is poor, the hazard of decalcification becomes great. It is sometimes comforting to be able to markedly attenuate the treatment goals and reduce treatment time. The nonuniform response to treatment is another factor that relates to the necessity for a therapeutic diagnosis in some cases. Is the patient particularly susceptible to root resorption? Why is it that, for some patients, a headgear seems to work well and yet for others there seems to be no response? Can we make this judgment in all cases before we begin treatment? Do lower arches in all eases come forward when Class II elastics are used? Biologic variation militates against the use of literal interpretation of “rules of thumb” and “diagnostic tricks.” Summary
The objective of orthodontic treatment is to establish optimal proximal and occlusal contact of the teeth within the framework of acceptable facial esthetics, normal function, and reasonable stability. These objectives of treatment for an individual are not always compatible, and good clinical orthodontics consists of achieving a balance between these factors. Proper classification (systematic description) and diagnosis are prerequisites for determining the nature of an orthodontic problem. Once the nature of the problem has been determined, a treatment plan can then define the steps necessary to achieve a balance of the objectives of treatment. A definitive treatment plan can be formed only after a definitive diagnosis has been made, In many orthodontic problems it is not possible to make a de finitive diagnosis prior to instituting therapy.
Experience has demonstrated that any malocclusion can be treated without tooth extraction but that in some cases such treatment would offend the requirements of acceptable facial esthetics and reasonable stability. Often it is not possible on an a priori basis to determine the effect of treatment on facial esthetics and upon the stability of the denture, particularly in borderline problems. Another difficulty confronting orthodontists is that the cause of a malocclusion is rarely known. As long as this is true, there must be some uncertainty in the treatment plan for the correction of the problem. Frequently, the response to treatment should alter the final diagnosis and the ultimate treatment plan. Therapeutic diagnosis is a procedure in which an initial diagnosis is made, in the face of some uncertainty, of the most likely cause or nature of the problem. An initial stage of treatment is based on this diagnosis and the response to treatment is used to confirm or modify the original diagnosis and treatment planning. Until we know more about growth prediction, the etiology of malocclusion, and the reasons for different responses to treatment, a type of therapeutic diagnosis will continue to be an important adjunct in orthodontics. The patient’s cooperation and oral hygiene are also variables which must be evaluated before an irrevocable treatment plan is established. It has been suggested recently that “orthodontics has moved beyond the pragmatic and empirical level and has become a profound science.“10 We believe that attempts to eliminate uncertainty from orthodontics are laudatory, but at present pragmatism still has an important role in orthodontic practice. Until more reliable diagnostic methods are available, perhaps orthodontists should view the testing of treatment response as a tool rather than a shortcoming. REFERENCES
1. Angle, E. H.: Treatment of malocclusion of the teeth, ed. 7, Philadelphia, 1907, 8. 8. White Dental Mfg. Co., p. 63. 2. Ackerman, J. L., and Proffit, W. R.: The characteristics of malocclusion: A modern approach to classification and diagnosis, AM. J. ORTHODONTICS 56: 443-454, 1969. 3. Case, C. S.: Some principles relative to preservation vs. extraction of deciduous and permanent teeth, Dentist’s Magazine 2: 1028-1030, 1907. 4. Tweed, C. H.: A philosophy of orthodontic treatment, AM. J. ORTHODONTICS & ORAL SURG. 31: 74-103, 1945. 5. Horowitz, S. L., and Hixon, E. H.: Physiologic recovery following orthodontic treatment, AM. J. ORTHOWNTICS 55: l-4, 1969. 6. Wallace, J. S.: Essay on the irregularities of the teeth, London, 1904, The Dental Manufacturing Co. The functional matrix. In Kraus, B. S., and Riedel, R. A. (editors): 7. MOSS, M. L.: Vistas in orthodontics, Philadelphia, 1962, Lea & Febiger, pp. 85-98. 8. Weinmann, J. P., and Sicher, H.: Bone and bones, ed. 2, St. Louis, 1955, The C. V. Mosby Company. 9. Enlow, D. H.: Wolff’s law and the factor of architectonic circumstance, AM. J. ORTIIODONTICS 54: 803-822, 1968. The evolution of diagnosis to computerized cephalometrics, AX J. 10. Ricketts, R. M.: ORTHODONTICS 55: 795-803, 1969.