Are Class II necessary?

ROBERT S. FREEMAK, D.D.S., X.S.D.

Denver, Colo.

INTRODUCTION

ALTHOUGH my orthodontic experience is comparatively limited, I have found that most orthodontic treatment can be carried to a successful conclusion wit,hout resorting to the use of Class II elastics. Therefore, in my opinion, the use of Class IT elastics is seldom necessary, and in many cases I would consider their use con- traindicatcd. My first thinking along these lines was initiated during my graduate training in 1949 by an unforgettable remark made by Dr. Waldo Urban, who commented that he did not often use intermaxillary elastics in his office because he could not find the kind that most men seem to use-the ones that pull in only one direction. There are occasional cases in which the reciprocal forces of Class II elastics are desirable, but generally in Class II correction the only force desired by the operator is the distal force on the maxillary teeth. If this is true, it seems more logical to use appliances that create only the desired distal force on the maxillar!- teeth without the concomitant undesirable mesial force on the mandibular teeth. The extraoral appliances, of course, would satisfy this requirement, and the two that I use are a cervical gear directed against the molars and a high-pull headgear attached to the anterior part of the arch wire. I realize that there is nothing unique or original in the ideas presented here, as many orthodontists are making extensive USR of extraoral appliances. However. there are also many orthodontists who are not using them or who are using them in only a limited way or mostly for Class II mixed-dentition treatment. This article will discuss the use of extraoral appliances as the principal foy.~ irr treatment of the permanent dentition.

CLASSIIELASTICSVERSUSEXTRAORAL AXCHORAGE It is not within the scope of this presentation to give a complete history of the use of Class II elastics and extraoral a,ppliances, but some conclusions and

This thesis, which was given as a partial fulfillment of the requirements for cerri fication by the American Board of , is being published with the consent and the recommendation of the Board, but it should be understood that it dne~ 1101 necessarily represent or express the opinion of the Board. 3 6 6 E’rtmnnn Am. J. Orthodontics May 1963 observations made by other orthodontists rclativc to these subjects are of interest. In 1938 Brodie, Goldstein, and Nyerl published the first cephalometric evaluation of Class II, Division 1 cases treated with intermaxillary elastics. They concluded that in all of the cases studied the mandibular teeth were moved forward by the intermaxillary force. They further reportoil that the maxillary dental arch remained relatively stationary under the forces of Class II elastics, thereby indicating that most of the correction had been obtained by the undesirable forward positioning of the mandibular teeth. Since that report was published, many other orthodontists have arrived at the same conclusion that the mandibular arch does not provide adequate for intermaxillary elastics. The following quotations express some of these observations : . . . With few exceptions neither mandibular anchorage nor ‘ ‘ prepared ’ ’ man- dilmlar anchorage without extractions can sufficiently resist the pull of intermaxillary force to effect posterior movement of the maxillary dental arch without the forward movement of the mandibular teeth. . . . In many cases where prolonged use of Class II elastics has been resorted to, the mandibular teeth move forward to an objeetion- able degree. This may result in an extreme labial inclinat,ion of the lower anterio teeth where they are unhealthy, unstable, and accentuate the chinless appearance of the patient. --Berctl. Fischer.~ I do not ordinarily use intermaxillary elastics in Class II cases because, in my judgment, since it is relatively easier to move teeth mesially than distally, the lower denture is in many cases moved forward off the supporting base boric by this therapy into an intolerable position, and this is followed either by an increase in the protrusion or (in the presence of good muscle tone in the ) by recoil re- sulting in crowding in the anterior section. --Wazao Urban..? Stationary anchorage is a noble theoretical concept; pract,ically, the mandibular teeth either tip forward or slide forward on the base under prolonged rtastic: at- tack. . . . -T. ill. Gmh,‘r. IV:C are on precarious ground when we use mandibular teeth for anchorage and subject them to prolonged forward horizontal stress. These teeth, like the teeth to 1~ moved, are embedded in living and if it is easier to move teeth mesially than distally, the teeth of the mandibular arch are especially unsuit,able for clffective I’?- sjstance to a forward elastic pull. --Stcphen C, IIopkins.:~ In an analysis of the components of force resulting from Class II elastics, Bien” concluded that “the deleterious forces exerted arc grcatcr than the useful distal driving component of force in the distal movcmcnt of teeth.” He pointed out particularly the undesirable clcvating force on t,he lower posterior teeth, which would have a tendency to tip the occlusal plane. Also, in a study of cases treated with cervical anchorage, King; found the changes in the occlusal plant to be very smdl as compared to the undesirable tipping reported by Tovsteins in cases that had been treated with Class IT elastics. It is claimed in some quarters that the use of Class II elastics will stimulate mandibular growth. I have never seen scientific evidence to substantiate this theory, and I do not believe that it is possible to stimulate the mandible to grow beyond its inherent potential by the use of Class II elastics or by any other means. If convincing evidence to the contrary is forthcoming, you can be assured that I will modify the treatment plan advocated in this article and use Class 11 elastics vigorously on every Class II case that enters the office. In regard to whether or not olthodontic treatment can influence mandihhil~ growth, the following opinions arc cited : . . . There is not enough evidence at hand to support a definite conclusion OW! way or the other. -Wendell L. Wylit.9 As get, there is no map of determining whether or not the growth which OC- curs in a horizontal and vertical direction on the ramus of the mandihle is stimulated l)y orthodontic therapy. --rlTton W. Xoorf:.JO . . . Orthodontists apparently cannot make the maudiljle grow any more with tlwir manipulations than it would grow without them. --2’. At. Gyabrzr.! The resistance of the mandihle to enforced change does not permit intermaxil- lary force to change its growt,h pattern, size, or position in the manner desired. --IT{ rcu Fiwhf r.: Est,raoral anchorage was introduced in the ninrtcent,h century and I)c~~am~~ quite> popnIx in the early part of this century. Then, after a period oi quiescence, in 1936 Oppenheim’l publishecl a paper in which hc reco~n~nc~n~l~~~~ extraoral anchorage based on the same principles in vogue today. lie atlvocsated acccptanccl of the position of the mandibular teeth as being the most, cor1~1 for the individual patient and the USC of occipital anchorage for mo\-ing the* maxillary teeth distally into correct relationship with their inltagonists. thtlrbby avoiding any possible disturbance of the mandibnlar t,cdh. Oppenheim also pointetl out that the maxillary teeth should 1~ moved clistdly while> thfz face and mantliblc were growing downward and forward in their normal tlit~edorr. Jn 1947 Rloehnl’ cited Oppenheim’s ccmcc:])ts and outlinctl ~1 trttilttrlent procetlurc for early treatment of Class II eases by means of ccr+al ttxetion. whereby hc hoped to reclucc the severity of the by guiding a- rcolar growth and the eruption of teeth. Since then there have appc~;~retl III~~J~ articles advocating the utilization of extraoral appliances and analyzing the+ t’ results. I’ischcr” has been one of the foremost proponents of cervical gt~ forcch against the maxillary arch. In his 1948 article he also stated that. i‘bccaus~~ 01’ t,he limitations to forward movement of the mandibular teeth in treatment. thca antcroposterior malrelationships of the dental arches in masillnry l)rot rnsions iL?lClstructnral mandibular retmsions must 1x1 cot~rectetl I)y a I)ostt~t’iot~ i~ioV(‘- tnent of the maxillary dental arch.” The effect of estraoral forces on the maxillary structures has bc(kt7 thg~ subject, (Jf innumerable investigations. In a cephn.lomctric study of ( ‘lass 11 trcatntc>nt. lIoorc’O concluded that there was ” no evidence to prove that. ortho- clontic treattnent influenced the normal forward growth of the trlasilla. *! ill- though htl clitl feel that posterior traction on t,hc maxillary d(~nt7~rc~cluring treatment definit,cly inhibited the normal forward movc~mcnt of the drnluw. More recacntly, Ricketts’” stated. “We can no longer accol)t the as att it~7mutable structure. Yigorous retraction force on the tcdh, particularly l)ar~itl- ICI to the ;ISCS of roots, appears to prrvent f(~~wi~r(l growth ant1 ev(111(‘aus~’ tl113 Inasilla to grow downward and backwartl.” Brodie ‘$I*L crphalomctric growth stutlies co11~1~clctl that clu?+ing notvtl:il growth the face grows in an orderly manner, with the jaws and the teeth being carried clownward and forward from t,hc base of the craniu~n. La,nd+ ;rlso reportc(l ;I remarkable constancy of the 55X-1 angle, ancl Ric*k(atts” : st,77(]! 3 6 8 Freernun Am. J. Orthodontics May 1963 showed a slight increase of 0.4 degree in the SLYA angle in the two untreated control groups. In contrast to the demonstrated constancy of the SNA angle in untreated patients, all of the cases to be presented in this article showed a reduction in that angle. The smallest amount of change was 1.5 degrees, and the mean re- duction for the group was 2.37 degrees. Similar changes in point A have been reported by Graber,16 King,? Klein,17 B1ueher,ls Hanes,lg Ricketts,13 and others, and all of the foregoing studies were on larger groups of cases. Ricketts’ cephalometric study compared the results of Class II treatment by extraoral force with those of treatment with Class II elastics. He found that in both groups point A moved backward with treatment, but “the SNA angle was reduced an average of 2.7 degrees with the head gear cases and only 0.9 degree with elastics-a three-to-one ratio of effectiveness. ” Therefore, it is generally agreed that cervical gear forces, particularly when applied during an active period of growth, will accomplish the desired results of withholding the forward movement of the maxillary denture and the forward growth of the maxillary alveolar bone. Whether or not the growth of the maxilla itself can be withheld is still a matter of conjecture.

C;ISE PRESENTATIOSS The cases presented in this article illustrate basically what was ac- complished during treatment in a variety of cases. Simplified tracings of the facial radiographs and profile photographs are the only records shown and complete discussions of the case analyses and treatment plans have been omit- ted. In regard to the of these cases, an attempt has been made to reduce this to a few basic measurements which I find particularly important and which illustrate the changes resulting from treatment. For evaluation of the skeletal pattern, the angles SNA and SNB and their difference are recorded. The difference between the angles SNA and SNB, advocated first by Ricdel,‘O is a relatively good indication of the anteroposte- rior discrepancy between maxillary and mandibular bases, provided that the SNA angle is within a normal range. In mesognathic faces, where the SNA angle is unusually high, and in retrognathic faces, where it is unusually low. the SNA-SNB difference can be deceiving if considered only as the angle ANB. For example, a 5.0 degree difference in a retrognathic or backward- divergent face with an SNA angle of 75.0 degrees would indicate quite a severe Class II basal relationship, whereas a 5.0 degree difference in a mesognathic or forward-divergent face with an SNA angle of 89.0 degrees would indicate a very nearly Class I basal bone relationship. There is another method”l, z2 which may be more accurate, since it takes into consideration the varying divergen- cies of facial type. Rather than introduce another measurement into the already crowded list of cephalometric values, however, I have used the SNA-SNB difference method in this presentation. To provide further information on the skeletal pattern, I have also used the YAP angle, which was introducecl by Downsz3 to indicate the angle of facial convexity, and the inclination of the mandibular plane to the NS plane. The NS plane is used rather than the Frankfort horizontal because of the greater degree of accuracy with which it can be established in serial radio- graphs. All angular measurements of the incisor teeth have been eliminated fronj this report, although I still routinely make five such measurements on all trac- ings. In recent years I have found these axial inclinations to be relatively unimportant in making the original case analysis. However, they are vc’r!, valuable in the evaluation of progress radiographs, and I strive to finish eac!h case with the best possible axial inclinations of the incisors, since I consider this extremely important in order to obtain the optimum in function, estheticls. and stability. I consider the most important dental measurement in my analysis to 1~ wha.t I call the Holdawayz4 ratio, expressed as the ratio between the distanc+ll of the most labial point of the mandibular incisor and the distance of the chin point, or pogonion, to the line NB. I am not cert,ain when Dr. Holdaway c~~lv&I his ratio, but he explained its use to me in March, 1956, and I have ntilizc,tl it with an ever-increasing appreciation of its value since that time. In recent years quite a number of orthodontists have become aware of the* significance of the Holdaway ratio and have stressed its importance in th(Gr writings. In a discussion of the Steiner analysis, WyliP states: “Holdaway has corrected what was an error of omission-failure to include the chin-point in appraising t,he face-by suggestin, e that the labial surface of the lower iri- cisor and the chin-point are ideally related to the ?;B plane when each is cqui- distant from that plane, give or take a millitnr~tcr (or at the most two milli- metrrs) . * ’ Tn a recent paper on cephalometrics. in which he has included the IIol(l- away ratio in his analysis, SteineP states: “The location of pogonion is rertainly one of the important factors in establishing facial contour a,ntl ii must be carefully considered alon, u with other factors mhcn clctcrmining tht~ proper placement of teeth.” LinclquGW described Holdaway’s method in his article on the manclibular incisor and stat)ed : “It is my opinion that any method of lower incisor positiolt- ing should take the chin-point into consideration. . . Hcrc WC SW the poail ioil of the bony chin being directly taken into account.” To illust,rate further the use of the Holdaway ratio. Fig. 1 shows tracings of three cases. In the first one (A) the mandibular incisors arc too far Iabia.1, the swond one (R) shows a good ratio, and in the third one (C) the mandibular incisors arc too far lingual. It should be emphasized that it is the ratio or rela- t,ionship between the mandibular incisor and thcl chin-point measurements whic11 is important, and not the actual number of millimeters for each r~adinp. dlthough this ratio has proved valuable, it is merely anot,hrr biologic measllr(‘- ment and, of course, cannot be considered as an inflexible standard or as ~II absolute value to which all cases should be treated. As with all other ceph;rlo- metric measurements, there is a great deal of x-ariation and ever:- case must lw considered individually. 3 7 0 Freeman

Fig. 1.

-5 ;d

Fig. 1. Illustration of the Holdaway ratio. A, Mandibular incisors are 4.5 mm. further forward than the chin point. B, Mandibular incisors and the chin point are an equal distance in front of line NB. C, Chin point is 6.0 mm. further forward than the mandibular incisors. Fig. 2. Effect of thickness of soft tissue overlying chin point upon Holdamay ratio. When utilizing the Holdaway ratio, many d&rent factors must be taken into consideration, the principal ones being the patient’s age, sex, growth poten- tial, skeletal pattern, and the soft-tissue structures overlying the points b(ling measured. In regard to the latter, Burstone2* pointed out the extreme variation in the soft-tissue architecture between different cases. Fig. 2 illustrates partial tra+ ings of four patients from my practice, demonstrating the effect that the thickness of the soft tissue overlying the chin point has upon the Holdaway ratio. oh- viously, a t,hick pad of tissue overlying the chin point will have the same effe~l as a more prominent pogonion, while a thin pad of Gssue will make the (zllin point appear less prominent. The Holdaway ratio is often significant diagnostically, and it is used princi- pally to give the direction in which the mandibular incisors should (and should not) be moved during treatment, rather than as an indication of the csac:t position to which they must be moved. To illustrate, if all other factors were approximately equal, I would be much more likely to resort to extractions in a ‘. borderline case ” of. the ratio was 5.0: 2.0 than if it wore 3.0 : 3.0, and it is almost cacrtain that I would not extract if the ratio was 2.0: 5.0. In the Ialto]. type of case, it would seem preferable to sacrifice some stability of the mandibular~ denture rather than to make the profile too concave, particularly if a consitlcr- able amount of growth could be expected. In cases with this type of ratio, iI: which the crowding is too extreme to make nonextraction treatment fcasiblt:, care must be taken with the appliance mechanics to keep from making the dry ture an)- more rctrusive than it was at the start, of treatment, if possible. One ot,her measurement included in the cases presented here is the measure- ment, of the maxillary incisor to the NP plane. Although this is not particularl>, useful diagnostically, since the position of the maxillary incisors at the end 01 treatment will be determined by that of the mandibular incisors, it does illnstrattt the amount that the protrusion of the maxillary incisors has been reduced during treatment.

CME 1. The patient, who was 12 years 1 month of age at the start of treatment, h;t~!

a Class 11 malocclusion with a Division ? tendency (Fig. 3). The skeletal pattern was fail. and there was slight crowding in both arches. Active treatment lasted 34 months, at111 growth during treatment was favorable. Ko teeth were extracted. Light cervical gear forcv m-as continued during the first year of retention. The patient’s cooperation was grnerall~ good. CME 2. TOP patient, who was 11 years 7 months of age when treatment C~I~III~IICP~~. had a Class II, Division 1 malocclusion (Fig. 4). The skeletal pattern was fair, anti thert- was no crowding in the arches. Growth during the 21 months of active treatment Wii.. favorable. The maxillary second molars were extracted. The maxillary third molars I,:Iv,~ now erupted into nice position. The patient’s cooperation was very good. Cask 3. This case involved a Class II, Division 3 nialocclusion (Fig. 5). The skelerel pattern was fair to good. There w&s no crowding in the arches. Eo teeth WWF: extmcteci. The patient was 14 years 3 months of age at the start of active treatment, which lasted 5 months. Growth during treatment was favorable. There probably was some manrlit,ula: post,erior displacement in this case. The patient’s cooperation wa:: good. Cask: 1. This 14year-old patient had a (‘lass Il. I)irisiox 1 nlalocclusion with t,inlasii lary protrusion (Fig. 6). The skeletal pattern was fair to poop’, an11 there was cousirlerai~lv Am. J. Orthodolbtics 3 72 Freeman ,Way1963

n.

Fig. 3. Case 1, Class II malocclusion with Division 2 tendency. n. C. Fig. 4. Case 2, Class II, Division 1 malocclu&on. Meaauremsnt Be!-ore

sN* - 80.0

SNB - 76.0

MTP. - 5.0

NS - Yand. - 19.0

NAP - 4.0

L-NP - 1.0 am.

ieNS - 1.0 m.

P-NB - 5.5 ml.

.I.

n.

Fig. 5. Case 3, Class II, Division 2 malocclusion.

Am. J. Orthodontics May 196::

"s,mmmmt Before After

NNA - 79.0 77.8

NNB - 76.6 76.6

Diff. - 1.5 2.0

NN - Ynd. - 11.0 so.0

NAP - 6.5 1.5

20NP .’ 12.0 1. 6.0 I.

i-NE - 7.6 m. 4.0 I.

PrNN - I.0 as. 2.6 1. ;4.

B.

Fig. 7. Case 5, Class II tendency with bimaxillary protrusion. Are (‘lass II elastics necessary? 3 -i 7

Yalsurement

NM. -

SNB -

DiEf -

W8 - Nan&. -

NJ..P -

1-w - i-we - P-HB -

B. c. Fig. 8. Case 6, Class II, Division 1 tendency with extreme bimaxillary protrusion. 3 7 8 Freeman

i-m -

i -WB -

P-"B -

3. (‘.

Fig. 9. Case 7, Class II, Division 1 malocclusion with bimaxillary protrusion. Volume 49 Are CIlass ZZ elastics necessary? 3’7 9 Number 5

22.6 m.

12.0 m.

3.0 sm.

A.

R. ci.

Fig. 10. Case 8, Class II, Division 1 malocclusion with extreme himaxillary protru&h. 3 8 0 Freeman Am. J. Orthodontics Mau 1963 crowding of the mandibular incisors. The four first premolars were extracted. Active treat- ment lasted 24 months, during which growth was slight but mostly in a downward direction. Cervical gear was worn during the first 6 months of retention. Cooperation from the patient was very good. CASE 5. The patient, who was 13 years 7 months of age at the start of treatment, had a Class II tendency with bimaxillary protrusion (Fig. 7). The skeletal pattern was fair. There was considerabler crowding of the mandibular anterior teeth. The four first premolars were extracted. Growth was negligible during the 25 months of active treatment. Cervical gear was continued during the first 3 months of retention. The patient’s cooperation was very good. CASE 6. This patient had a Class II, Division 1 tendency with extreme bimaxillary pro- trusion (Fig. 8). The skeletal pattern was fair to poor. There were slight spaces in both arches. The four first premolars were extracted. The patient was 13 years 6 months of age at the beginning of the 26 months of active treatment. Growth during treatment was very favorable. Retention in this case will be difficult. A tooth positioner was used for the first 6 months to perfect the occlusion and to prevent while the patient was asleep. All third molars are now in good functional occlusion. The patient’s cooperation during treatment was spasmodic. CASE 7. The patient in this case was 12 years 9 months of age at the beginning of treat- ment for a Class II, Division 1 malocclusion with bimaxillary protrusion (Fig. 9). The skeletal pattern was fair. There was extreme crowding in both arches. The four first pre- molars were extracted. Active treatment lasted 25 months, during which growth was favor- able. Class II elastics were worn during the day for the final 5 months. The patient’s co- operation was generally good. CASE 8. The patient had a Class II, Division 1 malocclusion with extreme bimaxillary protrusion (Fig. 10). The skeletal pattern was very poor, and there was extreme crowding in both arches. The maxillary first premolars and second molars and the mandibular second premolars were extracted. The patient was 13 years 9 months of age at the start of treatment. Considerable growth occurred during the 29 months of active treatment, but it was all downward rather than forward. The maxillary third molars had erupted into position before treatment was concluded. I believe that the protrusion could have been reduced more if the mandibular first, rather than second, premolars had been extracted and if better mechanics had been employed during treatment. The patient’s cooperation was generally good.

DISCUSSION In most of the cases presented here many orthodontists, regardless of the appliance used, would have employed Class II elastics as a major part of the treatment plan. Class II elastics were used only in Case 7, where they were worn during the day for the last 5 months of treatment. In the foregoing case reports I have not discussed the reasons for extraction in those cases in which teeth were removed; nor have I discussed the treatment plan for each case, as it is not the intent of this article to cover the broad sub- jects of case analysis and treatment planning. However, it is my firm conviction that case analysis is the most important phase of orthodontics, provided that the analysis includes a determination of the forces and mechanics to be utilized in order to obtain the optimum result for each case. Too many orthodontists have a tendency to end their case analyses with an answer to the one question: “To extract or not to extract?” Then, depending .on their decision, they proceed to treat the case with exactly the same mechanics used on all their other extraction or nonextraction cases. Orthodontic patients are much too individualistic for this type of group therapy. In two cases that might look almost identical in a Volume 49 Are Class ZZ elastics necessary? 381 Number 5 comparison of the plaster models, skeletal patterns and soft-tissue architecture could be entirely different. Extractions might be required in both cases, but in one extensive extraoral forces and Class III elastics would be indicated, whereas in the other extraoral forces would be contraindicated and Class II elastics might be very necessary. In a recent article, Steiner2s reported the case analysis and treatment pro- cedures used for an extremely difficult Class II, Division 1 ease with crowding and bimaxillary protrusion. Following premolar extractions, full anchorage preparation was achieved and subsequently Class II elastics were utilized. The treatment was carried out by Dr. Howard Lang, and the result was one of the finest that I have ever seen. At the end of the article, Steiner made the following statement : “In view of evidence seen in cephalometric headplates and from other clinical observations, both Dr. Lang and I believe that it is also possible to treat cases of this type to advantage by positioning the mandibular teeth where thej should be by the methods just described and then maintaining them there while the Class II discrepancies are treated by extraoral anchorage. We know of no evidence that mandibles treated in this way show less indication of growt,h than mandibles that have been subjected to vigorous Class II rubber ligature pull.” The foregoing statement by Dr. Steiner expresses my opinion precisely, and the alternate treatment plan that he suggests for the ease in question would bc the one of choice in my office. The treatment of such a case would be st,arted with a relatively strong cervical gear force against the maxillary molars, and after a short interval (to be sure of adequate cooperation) Class III elastics would be employed to position the mandibular anterior teeth as close to an ideal ratio with the chin point as possible. Next, the cervical gear force would be used to correct the Class II relationship of the posterior teeth. Finally, the cervical gear would be relied upon for anchorage while the maxillary incisors were being retracted bodily (augmented by the high-pull headgear) to a normal overjet relationship. Admittedly, the foregoing is a difficult task, and the suc(~s of treatment is almost entirely dependent upon the patient’s cooperation. On t h(: other hand, is there any easy way to treat a difficult case of this type or ;m~. way that it can be successfully treated without good cooperation from the patient Y In the foregoing treatment plan, a distal force is used against the maxillar?- arch throughout the treatment, which should certainly bc desirable if we art: hoping to hold back the maxillary structures while the face and mandible arc growing forward. The treatment time will undoubtedly be longer than with the technique employing anchorage preparation and Class II elastics, but this should also be desirable when treating a growing child in or&r to take the opt irnunl advantage of growth. Since t,he treatment plan that I utilize seldom calls for the use of Class II elastics, and only then in cases in which forward movement of the mandibular teeth is indicated, anchorage preparation can be eliminated. This considerably reduces the number of arch changes and adjustments required, thereby lessening the amount of chair time required for each patient. Although it is not necessar) to prepare the mandibular arch for anchorage in the treatment plan advocated above, this does not mean that I do not use Cla.ss III elastics. In my opinion. it 3 8 2 Freeman Am. J. Orthodontics May 1.963

is very important in many cases to retract the mandibular anterior teeth to a more favorable position in the face, using the Holdaway ratio as a guide, and to accomplish this I generally use Class III elastics, utilizing maxillary cervical gear for anchorage. Class III elastics are also used to gain arch length in the mandibular arch in cases in which I consider this feasible, although quite often I prefer to accomplish this with a cervical gear against the mandibular molars. It has been pointed out that adequate cooperation from the patient is essen- tial for the success of this treatment plan, as, indeed, it is for almost any suc- cessful orthodontic treatment. Obviously, my practice is not free from problems of patient cooperation, but I never cease to be amazed at the degree of cooperation that most patients will manifest after the objectives of treatment are explained to them. In order to stimulate their interest, I show my patients their own records and then the successful results accomplished in similar cases. I stress that their cooperation in wearing their extraoral appliances between appoint- ments is infinitely more important in determining the success and rapidity of their treatment than the adjustments that I make every 2 or 3 weeks.

Fig. 11. Kloehn type of cervical gear and high-pull headgear being worn simultaneously.

I utilize a Kloehn type of cervical gear with rubber elastics attached to an elastic traction strap. I prefer this to just the strap itself, as it seems to be more comfortable for the patient, and it is easier to control the force and keep it uni- form throughout treatment. Also, it is possible to use lighter forces by changing the size or number of elastics as indicated during the accommodation period or in cases where a cervical gear force is continued during the retention period. In many cases, particularly where there is an problem, the patients also wear a high-pull headgear. This is attached to the anterior part of the maxillary arch wire and is usually worn in conjunction with the cervical gear as illustrated by the happy patients in Fig. 11. These excellent patients have every reason to be happy in the realization that their cooperation played a major role in effect- ing the treatment results illustrated in Fig. 12. Are Cl,ass 1I elastics necessnry? 3S:l

Fig. 12.

Class II elastics create an undesirable force on the mandibular arch which generally has detrimental effects. As yet there is no evidence to support thcx claim that Class II elastics stimulate mandibular growth. There is considerable evidence to support the claim that extraoral forces. when applied on a growing child, are capable of withholding the forward mo\-c- ment of the maxillary denture and the forward growth 0 the maxillary alveolar bone. I consider the position of the mandibular incisors anteropostcriorly iu thlb face to be very important in case analysis and treatment planning. An excellent method of determining the optimum position for t,he mandibular incisors, taking the chin point into consideration, was introduced by Holdaway and has been explained in detail. Important factors that must be taken into consideration 1))- t,he orthodontist utilizing the Holdaway ratio are the patient’s age, sex, growth potential, skeletal pattern, and soft-tissue architecture. Class III elastics, worn in conjunction with a cervical pear against the maxi1 la.ry molars, are often required for retraction of the mandibular teeth tn th(bir 3 8 4 Freeman Am. J. Orthodontics May1963 optimum position anteroposteriorly and/or for gaining arch length in the man- dibular arch. Although the procedures advocated in this article may lengthen the treat- ment time, this could often be considered desirable if the treatment is timed to correspond with the period of optimum growth potential. Since successful treatment with extraoral appliances is entirely dependent upon the patient’s cooperation, it is of the utmost importance that the ortho- dontist explain this basic fact to his patients and inspire them to accept their responsibilities throughout treatment,.

CONCLUSION Class II elastics are not necessary in the treatment of most orthodontic cases and, although they are occasionally indicated, the principal distal forces required against the maxillary arch can be obtained more advantageously through the use of extraoral appliances.

REFERENCES

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