Are Class II elastics 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 Orthodontics, 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 anchorage 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 lips) 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 bone 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 malocclusion 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 maxilla 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.