Tandem concept in the nonextraction treatment of Class II malocclusion

American Journal of ORTHODONTICS Volume 68, Number 2, August,

ORIGINAL

1975

ARTICLES

Tandem concept in the nonextraction treatment of Class II malocclusion Chris Philip, D.D.S.* New York, N. Y.

A

basic decision that an orthodontist must make prior to selecting the mechanotherapy of choice for the treatment of a specific malocclusion is whether to maintain the integrity of the dental arch or to proceed with the recommendation that certain teeth be removed. Fortunately, this decision in most cases is clearly determined by the case analysis. However, there are malocclusions which are classified as “borderline” cases and, unfortunately, it is not clear whether or not extractions are indicated. This uncertainty may, at times, lead a practitioner to translate this erroneously in terms of “when in doubt, extract.” I am certain that very few subscribe to this thesis, even though it may be clinically expedient in light of some of our presentday techniques. It is the purpose of this article to present a, systematic, controlled nonextraction approach in the treatment of certrrin selected Class II malocclusions exhibiting arch-length deficiencies which can be considered “borderline” problems. The term tandem is used to label this conservative method, since it involves the selective deployment and utilization of mechanical forces to initiate simultaneously various groups of tooth movements in one or more areas of both dental arches. An attempt is made to synchronize this force system with the natural forces of growth inherent in the individual dentofacial complex, thus effecting a complimentary biophysical action whereby a more continuous type of corrective movement is achieved within a reasonable period of time. In essence, the main objective of this treatment approach is to gain a “Former Chairman Center; Assistant Fairleigh

Dickinson

of the Clinical University

Department

of Orthodontics, Bronx-Lebanon Hospital Professor, Graduate Department of Orthodontics, School of Dentistry.

119

sttfficicwt ittc.twtw itt tlita atttc,t,ol”‘slt~t,iot’ atrtl tttc~tlic~lat~~t~;t1 clinrcbltsiotts oi’ t~oili tll(l IlI;tXillitt~\~ illltl matt~lilIuliIt~ tl(1ttt21 ill’(‘ll~‘S SOtllill tll0 il~ll~tllIlt tll’ Sl);lC’(’ I’l’C’;lt(‘(l \vill IW ;ItlNJuatc to Iy~ositiotI i11~1101’111i111~~ tliSplil(Y’tl uttits into fItc*it’ It0t’ltlitl itttc~t.o~c~lusal and iIttcIittc+is;tl t’c,l;ItiottslIiJts. To acltiovc~ tliis (xticl witliottt ~~twportiotr>ItCly ilIt(L aclvcrS(11;7iIIflucwcing tltcx daLilit>- itttl(>s itIl(l t’ilCiit1bitl;ttlW Oi’ tlltb (‘iI%‘, tllcwl tlcsitwl Cllilll@‘S arc l~~oilglit ;thout withitI tlto tIt~ttt’otttlIs~~ttj;lt’ horittcl;tt~ic~s imposctl I))- the intlivitlual’s ltiogcttcdc tititlx-Itp. Siitl%tltiltltt~’ st:rtvs : “Jlasill~tl’> clctttal arches I\-ill show ttlktillt~~lti~ltcY~ of’ c~sJ)artsiott provitlctl flliI~~tiOlliIl wtivit;\ is iltl(Vlllatt’ atIt tlelttal O~~lllsal t~clatiottsliip h;tS hWtI c*olYYY+Ul.I lo\?- IllUClI il11.J giwit tlcittal arch can 1~ tritlcnctl without snhscc~ucttt rclnpw tlopc9t~ls oil (a ) adcquatc basal arch, (II) pr~opw ntits(~I~~i’iin~tioit, CV) lhc J,olcwtial 01’ the genetic growtlt pattern, aittl (tl ) c~lititittatiott of prwsitrc 1t;rbits.” The ntwhanics involvrtl iIt trcatittg thcsc quwtiottablr ~asw lie within the> fra,mcwork of .lamcs .Jap’s” “~~Xt~~lOI~itl forw tlICYil1)y.” The approac’tt that I use cliffcrs only in the auxiliary t1lWltitt1iSlltS that itIY’ Ittilixcl(l illltl 1~110 tllilItl1~‘1’ in wlticli they arc npplictl ant1 atljustctl. .JaJ- emphasizes the ittIJ~ortattw of timing iIt tI’~‘ilttl1~~llt aIlcI tltca c~lIanttc~liIIg Of growth anti tlevcl0pmeIIt So tltitt ill~ttOt’Ittill cttvitw~trtrtilitl iIIflwiiws \VOl~l~l h WlklOvd 01’ rducW1, thus iIllO\Vi?lg tllcl tlclttlll~t~ to itSSt1111~’ its ttortnal IIlilSimum inherent growth pattetw iltt~l rc~tttlct~ a Jwsit,i\-ch irnpI~ov~~Ittt‘ttt itt l’acial hat?11011y.

1 II 1963 \Vcislander2” made it prt~liminary wphalometric iitvestigat,ioiI ant1 fout~tl that cstraoral force not only dfectetl the dentoalveolar area of the tnaxilla but also influenced ant1 altwctl the tlirwtiott oi’ growth of’ thcl rraniofacial pattern. TIis findings w~~t~c a fitCtll?ll prcsentatiort oi’ what, many clinicians intuitively thought hacl occurwcl cluritIg treatment. This orthopetli~ aspect, of out treatment proceclures has certainly been helpful iIt ~orwctittg ma~illom;ttItlil~~~l~tI~ Inalrelationships in the child patient. TlIe basic extraoral sctnp is cmploycd, tltercfow, as alI active unit of l’otw in that it can act ;Is an orthopedic appliance as well as XII orthodontic applianw for the distal corrwtion of the maxillary postwior teeth. Because of the critical space rcquirrmettts tltat “hortlerliIIc” eases exhibit, it minimum numhcr of bands with ctlgcwiw attaclImeItts iire used ant1 Class 11 mechanics arc avoitlccl. Individual tootlt movements ift the antwior section of the dental arch arc arc~omplishctl by means of ltighly resilient light ilrch wires. \Vlicit reciprocal forces arc itcc~lcd. tltcl cdraoral setup bccomcs a stabilizing agent, thus ensuring positive cotttrol of anchorage. Rationale

for

the

selection

of

a treatment

plan

A strict atlhcrcnce to any one pa.rticular dogma of’ treatment ntay cnablc the practitioner to perfect his tcchniquc but, by t,hc same token, it Ina>- stifle diagnostic acumen and lessen pragmatic flesihi1it.v. The many tlentofacial abnormalities that confront the clinician in his practice demand that a specific appliance therapy he adapted to the condition rather than the caondition to the appliance. The benefits and the inadequacies of a specific mechanotherapy should be carefully assessed, and thwt the tnost desirable features of a particular ;tp-

pliance technique should bc adapted within the framework of one’s total armamentarium. Knowledge, clinical training, and experience supplemented by imagination and enhanced by Common sense should guitlc the operator in determining the therapy of choice for a specific case. Kegardless of what mechanothcrapy is utilized, its hiomcchanical and nltimate effectiveness is dependent upon (1) proper diagnosis (and evaluation) of the individual malocclusion, (2) the operator’s skill and knowledge of the limitations present in each specific case, (3) proper design, construction, application, and adjustment of the appliance being utilized, (4) physical and mental health of the patient, and (5) patient and ~~~/rent cooperation. These are some factors which must he gi\m careful consideration if one is to aehitvc a reasonably stable therapeutic result. The justification for selecting a treatment plan dcpcnds on whether one can, through his medium, attain the three basir but universal objectives of trcatmerit : (1) an increase in the functional efficiency of the masticatory apparatus by which the health of the teeth and investing supporting t,irxucs is maintained or improved, (2) an esthetic balance betw-cen the patient’s dcntofacial complex and his racial biogenetic form, and (3) insurancr of stability of the end result by obtaining a dynamic equilibrium between the adjusted occlusion and surrountling neuromuscular forces. Wilsonz7 maintains that “objectives in orthodontic treatment must not be subordinate to the limitations of an appliance. Valid objectives must be defined first and then mechanical means must bc sclcctrd to implement these objectives.” Criteria

for

case

selection

The majority of orthodontic problems that comprise an orthodontist’s cast load are Class II malocclusions. Accordingly, numerous articles have been published in the various orthodontic journals concerning the diagnosis and the corrective measures employed to resolve this orthodontic anomaly.R, lli* Is .Jarabak and Fizzelll” have classified Class II malocclusions as (1) dentoalveolar, (2) functional or neuromuscular, (3) skeletal, and (1) a combination of dentoalveolar and skeletal. The specific Class II malocclusions that have been of great concern to me have been those conditions in the early permanent dcntition commonly and loosely referred to as “borderline” problems. Schwabz2 broadly defines a “bordcrlinc” case as “one which has a good profile accompanietl by an arch length discrepancy.” Upon elinieal examination, many of these eases appear to have similar characteristics, in that they have a (I) Class TI molar relationship, (2) linear length, apical base, and dental arch witlth deficiencies, (3) malalignmcnt of maxillary and mandibular incisors, (4) a modcratc to exccssivc tlrgrcc 01 antcrior overbite, and (5) a favorable intcgumental profile. The diagnostic media which served as a basis of arriving at a differential diagnosis were a medical and dental history, study moclels, photographs, intraoral and extraoral radiographs, clinical examination of the patient, anti, wherever possible, an examination of other members of the family. \Yith these diagnostic tools, certain salient c.ritrria were tstablishccl to act as il guide

it, wlwting t1111yttlostx (‘lilss I I (*;Is13 \\Iricdl~ ~~0~~1~1 111,iltJl~‘H;ll~1l’ Ir, 11101.;1]1~ I)!this rloilt~sti~ilt~tio11nicdlotl. S~wific;~ll,v, tilt> f;lPtOl’s ttiilt \\‘(‘I’(’ givcln c*;rrt~l’ul cwtrsi~lt~l21ioll il t1tl IJl’ovt.(I to lw oi’ pwctical valut~ ii1 (‘ildc’ st~lt~vtio~~\z‘crtx ( I ) ;lgc~ ilIlt so\: II~’ ~)iltic~lll ;lS wlattltl to timing in thrmpy, (2) 1110 fhXtt’Jlt Of 111t3 liJltxilr ;ll’(‘tl Itlrlgtll, hil%II awli, and tlcntnl awli width t?dic*icwcaic3,(3) tht, st~vc~ril>’01’ ;Iritc~r~i~l)ostt~l~ioi~ antI inctliolatt~ral toot-h ttispl:lcclnc~llts, (4 ) to]ricGty of or;If’;lt*i;ll tllllSt~IJliltlll~~~. \vitll partit~nlwr cmph;isis 011 ttitl ln~wiiralor muscle, ( .j 1 I iic ~~icwiw ot’ piwsnJ’t’ hahits. (6) the inttyumcntal prtdilt~. ( ‘i) 111~Itw~l (II’ coolwatirnl ;rnti~ip:~tt~tl, ( 8) tlic> cariw intlt~s. (9) sixc, stiapt~, illltl position 01’ thirtl JlIOlilrS, ;l1lt1 ( 101 tht’ Ir\-~1 01’ rruption ot’ sccontl mol~r~~s. Timing

in therapy

l)cwcl’ strews “the irnportancc of timing in tht~l*iti)~ for it (1 ) rwcrsc’s an> rllcro:>~hn~cllt of space ~IOSUW in thta illtGpient stagr, (2) iilt(lrs the tlirwtioll of growth of tht: maxillary strncturcs to ii more favord~lc tliiwt,ion, (3) guides the eruption of the teeth in normal paths, (4) obtains thta lxw+its of’ rapitl growth tltw~lopmcnt.” 9incr a wide range of intlivitlual variat,itm twists. it is impossihtc to pwtlici specifically- the tdtwt, antI tlirwtion 01 growth ant1 cltwlopmc~rt of the various Soft - illltl hard-tissue wmpoiic~nts of fhc tlcntot’acial complex of ilJJ intlivithuil cast’. I lowcvcr, thtl scs aiitl t~lirtmolt~gi~ age of’ tilt> piitiwt (‘ill1 hti of v;Itllt~ in guitling tht> t~lilliciiln to time Iris tWatJlJcJJt during tllilt pcriott thilt ttJt1 I)ilt,it’Jlt Jllil~ bt niitlcrgoing ill1 optimum glY~\Vttl SpUIT. King” points out, that IllilSiJlllllll tooth movwnt~nt will otw1r simi~ltanct~usl~ with optimum facial growth ilIl(l tllilt “the fact> grows I’orwartl at thtb rate of up to 0.75 mm. to I.25 innI. in thtl IO- to I%yt~ar-old girls ilIlt Up to 1.5 mm. in boys of this age group. In girls 12 to 14 years or age UJ) to I Jnm. ot’ growth pt” \-car will occur, ant1 in sonif~ thew will hc little if any growth. At’tckr pnhcl’t> the growth rate in girls appwrs to clct~tinc Stlilrpl~. (I JwvttJ wntinues in ht)yS 12 to 14 Vt’ilrS Of iI&’ at tIltI I*;tl(‘ Of’ RN lJJUcll aS 1.0 IllUl. 10 I.5 lJll11. Iwr year.” Bul&t)llta’ has illustratctl gri~phi~ally thilt boys Ilot 0111y nl:ltnl*t~ later th:in girls hut that the clcgrtc of matural-ioll is consiclt~rahly greater, in(licating thilt’ it may I)c mow tbirahlt~ to hgin tYt’;ttlllcIIt of girls t’iJVlirY tIliIt1 that of bogs, and that may awouilt for tht> (liffcrtwws in resptmst~ to twatment tluring thts tlarly pwniantwt tttlntition. V;nl I$i~tta antI Bi~mhh;l’5 nlaintain that, ~TPII tllough thcrt~ is itrtlivitltl;ll Pill”l!with iItlVil1ltTtl St<~‘lt’till age 1lilVt’ variation, tliosr ‘LWIIO tt’Jlc1 t0 JJJiltllJ’t’ an PiJrly adolcstwit t’acdat growth spurt, whereas thtl tahiltlrt9i with rctartlcti skclrtal mat~nrntiorr tent1 to m;rturc laltlr.” Shuttlcworth intlicates thilt “mcnarche is closcl~ :lSStWiiItCtt with pliysi~al siw and onsot of at~olesc~~iICC.“Y5 In IlrlliiJaii’s ttiKt~rciitia1 growth stutly, iIs iiltlit2tctl in Snlzman~r’s”’ ttxt, htl shows that maximum growth of alnlt)st 7.5 lwr t*tlllt of “the total facial tlimcnsions listctl for Ix)>-s owIIrs at thtl SBIII~~ timrx tlrat masimum inc+rcascs in bright ilnti wight owur, usually lwt\\ctm stilgc 3’ (which is the lwginning of the eruption of pwniantwt stwmtl niol;~t’s at 12 ~C;II*S oI’ ;~gr) to stilgc 4A (whic*h is the

completion of eruption of permanent second molars at 76.05 years of age), whereas in girls maximum growth occurs much earlier.” Salzmann’l states: “Bi-canine length increases from 9-12 years of age in boys and 9-11 years of age in girls. Inter-molar breadth increases up to the age of 14 in boy and probably later, in girls it stops at the age of 13.” According to Sillman%P longitudinal study, posterior incremental growth is much greater than the increase in size of the dental arch width in the 12- to 14-year group. Brodie,” at a scientific meeting, showed that the apical base increases with age and, in turn, can increase the width of the dental arch through an alteration of muscle growth pattern. Study

model

analysis

for

arch-deficiency

cases

A series of measurements of the patient’s study casts were taken to determine the linear length and basal arch and coronal arch widths. These measurements were then evaluated according to Howes”” analysis. He has shown that the maxillary interpremolar width should be at least 43 per cent of the total maxillary tooth material from first molar to first molar, inclusive, and the basal arch width above the apices of the first premolars (canine fossa) should be slightly greater than the intercusp width. Cases with an intercaninc fossa measurement of 44 per cent will have a sufficient apical base for the expansion of premolars. If this canine fossa measurement is 37 to 44 per cent of the total tooth material present, then the prognosis will be yuestionable. A canine fossa measurement of less than 37 per cent would indicate that a definite tooth-to-arch discrepancy exists and extraction of first premolars would be required. Tooth size and arch width were assessed by a combination of dividers and a millimeter ruler. The intercanine and interpremolar widths were measured with dividers from the summit of the buccal cusp of one premolar or canine across the dental arch to the same point on the corresponding tooth. In determining the intermolar width, the bucco-occlusal groove was used as the point of reference. Maxillary and mandibular linear dimensions were measured bp adapting a piece of 0.028 inch brass wire on the cast from the mesial aspect of the left lower second molar over “the premolar teeth through their greatest diameters around and over the anterior ridge where the incisal edges of these teeth should be located for their most favorable anatomic and esthetic position and ending at the mesial marginal ridge”” of the lower right second molar. Sticky wax was used on the left side to help keep the wire in position. Integumental

profile

Photographs of the patient provide useful information concerning the integumental profile, muscle balance, and facial symmetry. In geographic areas where a diverse number of ethnic groups reside, the racial biogenetic form of the patient’s face and the growth changes of the component parts of the softtissue outline that occur should be given careful consideration. The nose, for

124

7%

i&i!/

example, is a struc+tnrc that cdontilirles to grow 111 in lIO\Vll\2.ill'tl ilfltl l'Ol'\\-il I’(i direction until early atlulthoocl, 21 illc rate of all iIT(‘t’>l~C J-early ifi~lwrsr 01’ 1 to 1.3 mm. in its over-all length.“’ III t,hosc tloubtl’ul cases in which thr sizcb of the nose is rather large but harmot~iousl~- relatctl to the lips a~(1 chin, I Iierilp~* with removal of teeth may excessively retract thr loner thircl of l-11~1 fac~c nlrtl can result in making t,hc nose appca r unusually prominent, with thcb possibilit? that the patient may have to undergo unne(‘essary rhinoplastic* suryyry, Rambleton’s” soft-tissue analysis reveals thilt : ‘*i 1 I tllr faw iI1 tlic at’m of the masilla becomes less convcs wit11 age in relation to the rest of’ the skeletal profile, (2) the soft tissue ov(‘r thtb maxillary bonc~ l~~~~n~est~hickcr, (3) thr> mandible grows forward more ant1 later in males that1 it tloes in females, (4) the soft tissue follows the hont of the niancliblc foiwirrtl. (5) tlica nose grows downward during adolesc~encc anti grows ~11 into i~tlllltllOOtl. ( 6) tll0 lips become longer and growth anti greater thickening o(*cnrs in the \-crmilion portion. ” level

of cooperation

Cooperation in orthodontir therap)- is not only unique in that it is rcquitrtl over a prolonged period of time, but it also is an elusiv(a force of such magnit,utlc and variability that it can render a c~c a success or a failure. A knowledge of the intrinsic and extrinsic factors that affect a patient’s level ol’ cooperation is, without question, essential. A patient.‘s home and social environment, his physical and mental health, his stage of physiologic and ps,vchologic tlrvclol~mc~nt, tlcsire for treatment, rapport, the mcchanotherap,v utilized, and ihe length of treatment arc but some vital factors that influence a patient’s level of continued responsiveness to therapy. It makes little cliff’crcncc what technique is usetl, if tlrc level of cooperation anticipated will be minimal, it would be in the best interest of both the patient and the parent that treatment be indefinitely post,ponctl Indications

for

extractions

In ‘%ordcrIinc” cases in which it is not feasible to inereasc the mandibular arch length because of an excessive degree of mandibular incisor crowding, mesial inclination of the mandibular canines, and mesial shifting of the posterior buccal segments, extractions arc indicated. This is equall,v true when the distal movements of the maxillayv posterior scgmcnts will not crcatc sufficient, space for the correction of the anterior ovcrjct maxillary incisor rotations and labially displaced maxillary canines. A dentition that has a high caries index with deep carious lesions and larg(x restorations that,, in the future, may affect the vitalit,?- of the pulp rcprcscnts a “borderline” problem that sl~oultl be trcatcd as an extraction case. Class I I malocclusions exhibiting market1 lingual inclination of the maxilIar> and mandibular buccal segments ma) indicate the presence of pernicious pressure habits, a hypertonicity of the orafacial musculat,urc, or :I combination of both. A simple but effective method to evaluate the degree of tautness of the surrounding musculature, specifically the buccinator muscle, is by inserting the first finger and thumb into the patient’s mouth, slightly retracating t,hc checks,

and telling the patient to swallow. The tactile sense of the clinician’s fiugcrs will enable him to determine whether or not the contraction of the buccinator muscle is excessive. To increase the circumferential dimensions of both maxillary anti mandibular dental arches in cases where the buccinator muscle is hypertonic will be an exercise in futility since a relapse would be the inevitable result. It would be far better to gain the nccessarv space by the removal of cacrtain teeth and make the necessary correction within the neuromuscular rrstrictions imposed by each cast. Molar

position

Some clinicians may recommend the removal of premolars for fear of impacting unerupted mandibular third molars with a noncxtraction technique. Unfortunately, impactions may still occur despite such extractions. The majority of third molar impactions are caused by improper vertical growth, extrcmelp short jaw length, and severe alveolar retrognathism. Assessing the amount of space that esists between the uneruptcd third molar and the second molar, the mesiodistal width of the crown of the second molar, and the erupting position of the third molar may enable the clinician to determine whether or not mandibular third molars may become impacted. Parents should be made aware that such an eventualiby may occur. Another important consideration is the level of eruption and position of the second mandibular molars. If the second molar has erupted past the distal cervical bulge of the first molar and its mesiodistal inclination is normal, uprighting the first molar to increase the linear arch length will not impede t,hc eruption of the second molar. General

mechanics

The four cases presented in this article have basically similar irregularities and the clinical application of the mechanics that will be described is similar in each case, differing only in details of appliance adjustment. To achieve a more continuous corrective change in different areas of both dental arches simultaneously, it was essential that an orderly sequence of tooth movements be followed. Any major deviation from this sequence would create a conflict in tooth movements and could precipitate untoward sequelae. In each specific case, there were slight variations in mechanics, but these were not enough to alter the projected order of the desired tooth movements. The sequential nature of these toot,h movements was as follows : 1. Correct rotated permanent first molars. 2. Increase the anteroposterior and mediolateral dimensions of both maxillary and mandibular arches. 3. Align rotated incisors. 4. Guide erupting permanent teeth to their normal intended positions. 5. Retract and intrude maxillary incisors. 6. Correct rotated canines and premolars. 7. Resolve transversely displaced lateral segments. Clinically, the above changes in tooth position played an important role in

126

Philip

/ ‘-1 @

I /

/

/

:j

\ \

Fig. 1. A, B, and C illustrates an offset-angulated double-tube molar attachment. It was designed in this manner so that the inner arch of the extraoral appliance will not bind with brackets on the premolars, ensure ease of insertion, and prevent the impingement of interdental papilla by the loop stops. This double tube (0.036 by 0.036 by l/d inch and 0.045 by l/e inch] is soldered at an angle of 35 degrees.

improving the vertical dimension of eac*h case. Appnrt~ntl!-, the vertical vector of growth was favorable and did much to augmolt this dcsirccl result. Ncvrrtheless, I doubt if this inherent potelltial woultl havoc Ill;tllift~stetl itsctll’ if trcatment had not been institutetl. Sequence

of tooth

movements

Before distal movement of the maxillary posterior segments is initiatctl, it. is necessary first to correct rotatetl nli~sillary first pt~riiiancnt molars. \Vhcn these molars arc rotatecl into their normal positions, there is ai1 antomatSic* inereasc in the linear length of the ma.sillary arch.!’ Rotating thcsc molal*s also permits the passive insertion of the basic arch into the molar tube atta~llnretlts (Fig. 1) without binding, allowing thcsc trcth to move botlily in their alveolar troughs. A highly resilient 0.016 inch round stainless steel are11 (Figs. 2, 4. antI I?) with small helical loops at the distal portion of t,his al*<*11is c*onstructctl alltl inserted. The type of molar rotation required will dictate the appl~opriatc adjustment to bc matlc at the tlistal extension of this itt*(*ll \virc. The IIrliral 100ps L’ to 3 mm. mrsial to the shcnth ot’ tllca mola1~ attachshould be approximatcl> ment. The distal terminations arc’ Inatlc passivr and I)cnt lil~gually without contacting the molar band. This atljustment will prevent the wire from irritatin$? the surrounding soft, tissues and will allow the molars to move distally without hindrance. The arch wire is ligated anteriorly to wide Siamese ltrackcts on thr maxillary incisor bands. If the maxillary incisors ncc~l rotation an(1 tltcll*cLis sufficient interproximal space present. these teeth t3i1 Iw i~ligllcVl wliilc the> rotated molars are being corrcetctl. The severity of the rotations 01’ t hcl in&or

Fig.

2.

An

appropriate tip

Fig.

inch

adjustments,

molars,

3.

0.016

Plastic

and

constrict

headgear

resilient can or

with

arch correct

expand

extraoral

wire

with

rotated buccal

helical

molars,

loop align

stops. and

intrude

This

arch

wire,

maxillary

with incisors,

segments.

traction.

A,

Parallel-pull.

8, Low-pull

C,

High-pull.

teeth will determine whether or not vertical loop configurations should be incorporated within the anterior portion of the 0.016 inch arch. These Stoner loops impart a gentle action of long duration to the arch wire and provide the means to align rotated anterior teeth rapidly. As soon as the maxillary first molars have heen rotated, which usually takes several visits, the patient is given the basic est,raoral appliance with instructions regarding its care, proper insertion and removal, anal the numhcr of hours that

Philip

128

Fig.

4. 0.016

020

basic s. s.

inch

s. s.

arch

heat

in place

treated

rd.

wire

arch . 045 rd. wire standard solder

Fig.

5.

extraoral spring

A

vertical steel

helical resilient

appliance. transmits

loop wire

Because gentle

tube

jt. coil

stainless

double

forces

spring (0.020 of to

hook

extension

and

hook

extensions.

is

soldered

to

termination with

coil

inch)

which

the

helix

and

the

molars.

the The

coil hook

extension, is

used

The

the this for

spring

inner Class

arch

is of

adiustable III

a the

loop

elastics.

it should be worn. A time sheet is provided for each patient so that the daily number of hours (14) can be recorded. He is also given a suitable case to store The component parts of the basic extraoral his appliance when it is not worn. appliance that are placed in this case arc ( 1) plastic headgear, (2) basic arch with swivel face bow, and (3) elastics. To gain the necessary high level of cooperation, t,he clinician must make sure that the appliance is comfortable, that his instructions are simple but explicit, and, above all, that t,he child patient understands the ultimate effectivcness of his appliance. Confidence in his appliance is quickly transmitted to the patient. To offset the tendency for the maxillary first molars to tip excessively distally, which can occur quite rapidly and impact uncrupted second molars, proper direction and intensity of force is imperative. This type of force is attained by placing the elastic hook on the “activator” at a position whereby the face-bow will be almost parallel with the basic arch (Fig. 3). A practical anatomic guide for the proper positioning of the elastic hook i?l. childre~~l is the inferior border of the tragus of the ear. The swivel action of the face-bow will ensure this “parallelism of forces” and will prevent cxcessivc tipping of these molars. There is greater latitude in the vertical direction with the swivel bow than there is with the soldered bow. The translation of force from the face-bow to the inner

arch is less likely to result in tipping of molars as a result of an alteration in the vertical positioning of the hooks. The degree of force that will initiat,e distal movement or effect an alteration in the direction of growth of the maxil1ar.y components need not be excessive. The orthopedic changes that ensue are due mainly to the “channeling” effect of the appliance on the inherent growth forces. Approximately 7 to 12 ounces of pressure is sufficient. The force that is transmitted t,o the soldered loop spring mechanism (Fig. 5) on the basic arch is derived from an elastic which is attached to a hook on a modified plastic headgear referred to as an “activator.” A Richmond gauge can be used to determine l-he number of ounces this elastic force exerts. The proximal contacts of the posterior segments should be tested with a piece of dental floss at each visit to determine if they are “mushy” in consistency. A “mushy” contact is a positive indication that the force is adequate and that, the patient has been cooperative. Tight contacts may stem from lack of patient cooperation, insufficient pressure, or a binding by the distal terminations of the 0.016 inch arch. Excessive pressure will break the continuity of the transscptal fiber pull (“lag in movement”), thus creating open contacts. The proper intensit! of force and the resiliency inherent in the design of the soldered loop spring mechanism are responsible for uniformly distributing this distal pull on the posterior segments. At times, as seen clinically, there may bc little, if any, transseptal fiber pull between the first premolar and the eaninc. The continuity of action of these interconnecting fibers may bc disrupted by the cxistcncc of a low buccinator attachment. Careful adjustments of the basic arch in the spring area must be made in order to prevent the possibility of rotating, constricting, or expanding the maxillary first molars. The basic arch should be passive when inserted in the 0.015 inch tube of the molar attachment and should always lie approximately 5 mm. anterior to the maxillary incisors. The anterior portion of the basic arch should be contoured in such a manner as not to cause irritation to the surrounding soft tissues. To avoid a unilateral response, the elastic force and the fact-bow length on each side should be the same. The double-tube swivel att,achment should be at the midsagittal plane, and the presence of any sleeping habits that the patient has acquired should be checked in order to rule out the possibility of a pillowing habit. When sufficient space is created by the distal movement of the posterior segments, the malposed maxillary canine can then be repositioned. This is accomplished by placing an attachment, which can bc a band with a Siamese bracket (Fig. 6)) or painting an acrylic adhesive on the labial surface of the canine to which a hook is embedded into the acrylic (Fig. 7). The patient is instructed to wear a I,$ inch latex elastic from this attachment to the hook extension on the loop spring, and this elastic should bc worn only when the basic extraoral setup is worn. Tn this manner, any unfavorable reciprocal mesial movement of the posterior segments while the canine is being repositioned will be negated. The force applied to the canine is in a distal and

Fig. Fig. Fig. Fig.

6.

Canine

7.

Pearl-on

8.

High-pull

9.

Rotation

band

with

acrylic

hook. with

anterior of

hook.

latex

hook.

premolar.

occlusal direction. At the salnc time, the forces of the extraoral clastiv shoultl he increased so as to cqualizc thr fork crcatrtl 1-p the ititramasillary latex elastic, thus maintaining tht> same prcssurcl formula on the molars. Rfttlr the maxillary incisors arc aligned and t,hc caanincs arc rclpositionc>tl, the anterior latcs auxiliary is then c~ml~loyetl to retrad ant1 intru(Ir the maxillary incdsors. The force shoultl lx approsimatcl~ 2 ounces. This l/1 inc?h latex elastic is attachctl lo high-pull hooks (b’igs. 8 ant1 10, ;1 ), which arc cithrr welded or soldcretl ontO th(t hasicz ;1rvh. The hook portion shoultl lit a(l,j>I(~eIlt,to distal third of the maxillary cxanincs. The (plastic is the11 engaged anteriorly to the incisal wings or hrackct slots of thr Siamcsc hracbkt+s. Iproper placernrnt of the elastic can also intrude or cstndc 0~1~’ or more’ incisor tdh. This is particularI\r Usef’lll

Whl

il

wJltl”al

frilc'tllrd

iJl&Ot’

hiIS

to

bl>

c~?ch”ll(t(‘(t

t0

itA

in&d

pht.

shoultl I)r lnatle so ils to prclv~~nt con&ction of the arch l,- the cspandcd anterior elastic.. Thcl intrusion of’ the inc%ors can be augmcntctl I,J- atljusting the distal helical loops of the 0.016 inch arch. To offset any unfi~voral-)le reciprocal tlistnl tipping of the first molars emanating from the distal tip-hack h~ntls of 111~0.016 inch arch, the cstraorsl elastic shoultl he attarhccl to a hook at ;I muc~h higher position OH the activator (I<‘@. 3). Sinec r&radon of the incisors is hcinp acc*omplishcd while the extraoral applianc*c is worn, there is no clangor of mcsial movement of the posterior scgmcnts. Also, pain is not cspcriencetl, thcrc is less danger of root resorption, ilIl(l appliance and intruding thcsc tWth adjustments are kept t,o a minimunt. Retracting hl

;Id~UStJJl~llt

0t’

ttl(,

lJilSica

ill’Ct1

Fig. 10. A, A high-pull

anterior latex hook (0.028 inch). It is soldered to the inner arch of the extraoral appliance. The hook portion lies approximately at the distal third of of the canine, to which l/4 inch latex is attached and is extended and engaged anteriorly to the maxillary incisor brackets. The action upon these teeth can be retraction, depression, elongation, or a combination of these movements. 6, A type of naked ligation resembles the letter N. This standard 0.010 inch ligature wire is used to ligate an wire (that is, a tandem arch) to mandibular incisors. This method of ligation provides operator with excellent retention in an occlusogingival and mesiodistal direction. mesial or distal tipping displacement of ligated units occurs. There is a minimum periodic adjustments. Correction of slight rotations can also be accomplished.

that arch the No of

simultaneously over an extended period of time usually negates the necessity of root torquing to improve their axial inclinations. If there is a transverse displacement of the posterior segments, appropriate adjustments of the lateral sections of the 0.016 inch arch can be made to correct these irregularities. An increase in maxillary arch width is mainly brought about by the growth changes occurring during treatment, and the action of the inclined planes of the mandibular posterior teeth as they are being uprighted buccolingually. The discrete interplay of these two force systems during the course of treatment permits this effect to occur. If this type of uprighting is acdcomplishetl too rapidly, there is little, if any, inclined plane action. Premolars which are rotated are banded, and a l/4 inch latex elastic is attached to either a bracket or a hook on the band and extended to the first molar attachment (Fig. 9). It is worn only when the extraoral setup is in position. This should be started when a neutromolar relationship has been achieved. While these dimensional changes are being brought about in the maxillary dental arch, various tooth movements in the mandibular arch are simultaneously being accomplished. Mandibular first molar rotations are first corrected, and these teeth are then uprighted so as to gain the necessary space to permit the premolars to erupt to their plane of occlusion. The appliance of choice used in the mandibular arch is known as the tandem arch (Fig. 11). It is an 0.021 by 0.025 inch stainless steel wire which is adapted passively and inserted into the 0.036 inch buccal tubes on the first permanent

132

Fig.

Philip

11.

elastics. Class

F, 0.018

Tandem

variations.

C, Gurin III

elastics, inch

lock

E, Gurin stainless

A,

Standard

compressing steel

lock round

coil 2

to arch

tandem spring,

3 mm. with

D,

arch. Gurin

mesial

to

Gurin

locks

6, lock coil

Tandem

arch

compressing spring

compressing

with coil

with

Class coil

Class spring III

Ill with

elastics.

springs.

molar hands. Open-cdl springs of O.OO!l-gauge wire with a lumen ol’ 0.036 inch is threaded bilatcrall,v onto the rectangular arch with sliding hooks m&al to these coil springs. These coil springs, in the uncompressetl state, with the sliding ~h~dtl hooks should extend up to the (listill thircl of the canines. Sufficient sp~e exist between the buccal surfaces of the posterior, segments and thr coil springs and hooks to prevent frictional resistance, Occlusal clearanw should also be established so that the arch will not Iw tlisturbecl by the huwal c~usps of the portion of the arch is seeurctl to the maxillary posterior segments. The antcxrior mandibular incisors by naked ligations, referred to as N-ties (Fig. 10, K j Class III mechanics are t,hcn ascd by extending a I,$ inch latex elastic from the hook extensions of the loop-sprin, 0‘ mechanisms on the basic awh to the sliding hooks on the tandem arch (Fig. 11, 11j . When these elastics are ill position, the patient is instructed to compress the coil springs gently. This eliminates the possibility of the hooks bindin, 0 with the wctangular arrll.

Tandem concept ill. wwextraction

treatment

133

Since the lumen of the molar attachement is 0.036 inch, it is not necessary to make compensating torque adjustments in the posterior sections of the rectangular arch, as would be the case if the lumen of the sheath were 0.022 by 0.028 inch, This ensures a full sliding effect of the molar on the wire. Another desirable feature of this type of sheath is that it can readily be converted with an insert, without removing the band from the mouth, into an 0.032 inch tube. As the mandibular first molars are being uprighted, minor rotations of the mandibular incisors can be corrected, usually without banding these teeth. If, however, the rotations of the mandibular incisors are more pronounced, it may be necessary to band these teeth and make the necessary corrections with an 0.016 inch arch. Incisors which are positioned too far lingually can be moved labially by the addition of Gurin locks between the coil springs and the sliding hooks. These locks are then adjusted to slightly compress the posterior coil springs (l/32 inch) (Fig. 11, C). Class III elastics are not worn with this setup. The application of Class III mechanics, as previously described, ensures positive control of the anteroposterior direction of these forces. For example, after the mandibular incisors have assumed their normal labial inclinations but further uprighting of the mandibular first molars is required, the sliding hooks under Class III mechanics will act as stops, thus preventing labial movement of the incisors. If the mandibular incisors have moved too far labially, they can be gently retracted under Class III mechanics by adjusting the locks so that they lie 2 to 3 mm. mesial to the coil springs (Fig. 11, E) . Increasing the total circumferential arch dimensions of the mandibular dental arch often necessitates the supplementation of these anteroposterior changes with lateral movements of the buccal segments. To achieve these desired changes, a highly resilient 0.018 inch stainless steel arch wire is selected. This arch wire is contoured to the symmetry of the mandibular teeth with approximately 5 mm. of expansion of the molar extensions. The wire should be perfectly level, with no bends incorporated in it. The arch is then secured by naked ligations to the mandibular incisor teeth and, at subsequent visits, to the remaining buccal segments. The inherent resiliency of the wire will initiate several distinct movements : (1) labial movements of the incisors and (2) lateral movements of both the canines and premolars. The mesial component of this force system becomes less pronounced in the mandibular incisor region when the buccal segments are tied to the arch. If the mandibular first molars require uprighting and the labial axial inclination of the incisors needs improvement, open-coil springs, of the same dimensions as previously described, approximately 5 mm. in length, are added with Gurin locks placed mesial to these springs (Fig. 11, F). These coil springs are then slightly compressed l/32 inch. This type of adjustment is made every 3 to 4 weeks for several visits. When the mandibular canines are tied to the arch wire, the force is distributed to the molars and canines. This results in a further uprighting of the mandibular first molars and an increase in the intercanine width. Very little, if any, labial thrust is exerted upon the mandibular incisors with this type of force system; thus, the corrected axial inclinations of the mandibular incisors are maintained. At the conclusion of the active phase of treatment occlusal interference,

134

Philip

such as canine tripping, is eliminated by selective spot grinding. This l~rocedurc~ is usually extended over several visits and initiated after the cast has hrtw in retention for approximately 3 months. The custornar!- retaining devices usctl during the passive phase are the maxillary Hawley rct,ainer and the soldered lingual arch from mandibular first, molar to first nlolar. This mantlibular f~xcd retainer is left in position from 2 to 3 years. After this period, it may be neccssary to continue mandibular rctcntion by substituting a modifictl Jackson retainer for the soldered lingual arch. Offset-angulated

double

molar

attachment

The type of molar tube arrangement as sketched in Fig. 1 is a modification of the standard double-tube molar attachment commonly used in extraoral force therapy. It was designed in this manner to ensure a wide range of flexibility in the application of the basic extraoral setup in conjuction with other mechanotherapies. ~l~~gulntio~ The degree of angulation, which has been calculated at approximately 35 degrees to the long asis of the molar, permits insertion of the basic arch without its binding with adjacent attachments ant1 without, its irritating the cheek mucosa. In certain cases, ptie7lt threshold and certain anatomic coGderations are significant factors which determine the degree of angulation : (1) buccal anatomy of the posterior units, (2) tonicity of buccinator muscle, and (3) thickness of buccal pad. The l)ul’pose of o&hefting the sheath is twofold : ( 1) to eliminate the binding of the basic arch with the tie-back loop or attachment and (2) to prevent the tieback loop or attachment from impinging upon the interdental papilla. 0.016

inch

resilient

arch

wire

with

distal

helical

loops

The 0.016 inch arch with high-spring properties, as illustrated in Figs. 2 and 4, is used as an adjunct in extraoral force therapy. It is engaged anteriorly within the Siamese brackets of the maxillary incisor hantls primarily to dqress i’xcisor units. In addition to this action, this highly versatile mechanism can effectively align rotatetl molars, align rotated maxillary incisors, ancl constrict or expand buccal segments (Fig. 12). These tooth movements can be accomplished either selectively or sim7iltn?leously. The distcrl helictrl loops incorporatctl in this simple 0.016 inch round arch permit a more gentle and positive act~ioll of longer duration, minimize the periodic adjustments, permit rapid movement, and ehminate impingement up011 the interdental papilla in the molar region. The degree of i)/frusil*e j)fo2:e))f(zt of the maillary incisors is dependent Upon (1) degree of tip back-bend, (2) inherent resiliency of wire, (3) size of helices, (4) distance of helix from mesial surface of sheath, (5) size of lumen of sheath, and (6) position of sheath on molar bantl. A disadvantage of the 0.016 inch arch with helical loops is the reciprocal tipping clisplaccment (distal) of maxillary molars. The dcgrec of reciprocal movement is proportionate to the extent of the intrusive action upon the incisor units.

Tadem

concept

Incorrect

Fig. 12. no

Adjustment

surface interference

bends.

C,

when

Correct

E,

rotations,

inch

mesial

and distal

wire.

A,

away

from

bend

movement and

for

the

reciprocal to

helices

and

no

formation

D,

removed.

LI arch

inch

Toe-in

of bends

correction action

will

To counteract these tipping it is necessary to (1) adjust the fulcrum (molar) (when the fulcrum to negate distal tion of patient in wearing

135

Correct

2 to 3 mm.

0.016

position or

Toe-out

bilateral arch

sheath with

inserted

molars.

of

of

trctrhent

1

0E

distal

it! ~~o~~txtrnction

result

of

of

bend

is made

4 to

molar

band

in order

that

irritation loop for

to

will the

buccal

prevent correction

distolingually

remaining as

A sharp

lateral

rotated and

B,

mucosa. binding of

5

of

mm.

there the

molars.

F, sections

be

Depressive basic

mesiolingually

anterior

from will

arch rotated

In

correcting of

0.016

indicated.

displacements, without lessening the anterior effect, the face-bow in order that the line of force is above depressing incisors, the line of force should be above tipping displacement of molars), (2) have cooperathe extraoral force setup, (3) regulate degree of

136

Philip

elastic pressure, and (1) adjust the basic>arch of the extraoral parallel to the plane of arch. Vertical

helical

loop

spring

with

coil

and

hook

force so that it; is

extensions

The spring design shown (Fig. 5) is a modification of the standard vertical loop spring commonly used on the basic arc~h in extraoral Sorcc therapy. It \.aries from the standard spring in both design and method of soldering. Each modification indicated below has made this mechanism a clinical asset. It exhibits l-he favorable features of both the standard vertical loop spring and the coil spring. XodificcrtioIls. The basic semi&c&r desigjl with its fixed point and free sliding end ensures adjustment, enhances tissue accommodation, and permits continuity of transmitted force throughout the working arm. A sftri,lless sfeel 0.020 imh rouxd l&c with high spri?lg prollerfies exhibits a greater resilient propert? than the precious metal variety. The c~i~rp solder J%H~ (greater surface contact) results in a more secure joint. The physical properties of the basic arch are not altered by overheating, since the tail extension rcceivcs the brunt of the heat. Helicnl coafigurcrfiolr provides for a more gentle action of long duration. Coil fermi?tnfion minimizes spring collapse. The hook exte~sio~~~(for Class III mechanics) facilitates placement of latex (l/1 inch) and does not hinder distal movement of maxillary molars; elastic force is in a morr horizontal direction. thus prcventing undesirable reciprocal movements of mandibular units. Soldered

or weldable

anterior

latex

hook

The design of the anterior hook shown in Fig. 10, d is a modification of the standard soldered hook used in extraoral force therapy. Its function is to proride a place of attachment for the 11’4 inch latex which is engaged anteriorly upon the maxillary incisor brackets. The action directed upon the maxillary incisors can be either a (1) retraction, (2) depression, or (3) a combination of these movements. The direcfiorr of the desired ?,lovemrnt is dependent upon (1) position of upright, (2) type of hook design, (3) place of attachment on brackets (bracket slots? incisal wings, or a combination of these areas of attachment). The upright is lvelded or soldered upon the basic arch, so that the hook partion will be approximately at the disftrl fhirds of the czsspids. The amount of elastic pressure upon the incisors from this distance is sufficient. Welding or soldering the upright further distally may result in irritation of the buccinator attachment. The lmgfh of fhe depressive upright is determined 1)~ (1) depth of mucobuccal fold and (2) amount of intrusive pressure desired. The hook was designed in this manner to prevent the elastic from riding down the upright during its active state. Advantages of this hook are that (1) a positive intrusive and retractive action is created simultaneousl;v and final root torquing of incisors is not required and (2) bends in the basic arch to accomplish similar movements are not needed. N-tie ligation. The type of naked ligation that somewhat resembles the letter

Tandem

concept i?~ nolbextraction

treatment

137

N is chiefly utilized in extraoral force therapy. A standard 0.010 inch ligature wire is used to ligate arch wires (that is, tandem) to anterior teeth (mandibular incisors) (Fig. 10, I?). To ensure the benefit of this ligation, it is necessary to heed the following step-by-step explanation : 1. Gingival and occlusal extensions should be held taut. 2. The gingival extension should then be directed over the arch occlusally at a position where a point of contact can be established with the labial surface of the tooth. 3. both ends should then be pulled taut and, if necessary the lingual portion of the tie wire can be positioned at the cervical margin with the ligature director. 4. The ligature tie pliers should then be used (four turns) and the pigtail then tucked gingival to the arch. For rotated teeth the procedure is similar, but with certain exceptions: 1. A 0.014 inch ligature tie wire is used instead of the standard 0.010 inch wire. 2. The gingival portion of the tie wire should be placed at that interproximal surface of the rotated tooth opposite the desired direction of movement. 3. The point of contact should be as far as possible from the direction of rotation so that leverage may be greater. Case

reports

Case

1 (Figs.

13 and

14)

P. B. was a Caucasian girl, 12 years 6 months of age, of Mediterranean ancestry. The medical history and clinical appearance indicated that she had no medical problem that would interfere with treatment. The patient had experienced the usual childhood diseases and did not have any respiratory allergies. She did not have any pernicious oral habits. Although the tonsils and adenoids were present, they were not enlarged and thus did not obstruct the air passages. Menarche could not be elicited from the history but it was safe to assume, judging from her chronologic age, that it would soon occur. An oral examination of both the mother and the patient’s brother revealed that they had similar malocclusions exhibiting (1) a Class II molar relationship, (2) labially positioned maxillary canines, and (3) crowded mandibular incisors. The patient’s desire to undergo therapy, the favorable parent-child relationship, and the rapport established were plus factors as to the level of cooperation anticipated. The patient’s photographs revealed a long nose, but this was harmoniously related to the lips and chin, giving her an orthognathic profile with good facial symmetry. The circumoral musculature was well developed and relaxed. Radiographs of the patient’s dentition revealed above-average resistance to caries, with several occlusal restorations. Root development and supporting bone appeared normal. Second molars were almost fully erupted, with the mandibular left second molar being rotated. Third molar buds were present and were of normal size and shape. They were in favorable erupting positions with the exception of the mandibular right third molar. There was adequate spacing between the maxillary second and third molars. Examination of the study casts showed the following irregularities: (1) a Class II molar relationship, more pronounced on the right side, possibly attributable to a mesial shifting of the right maxillary posterior segments, (2) an anterior overjet of 4 mm., (3) an anterior overbite of 5 mm. (supraocclusion of the mandibular incisors), (4) midline

Philip

13 8

Fig.

13.

age.

May,

Case

1.

Pretreatment

casts

and

photographs

of

Patient

P.

6.

at

121/z

years

of

1959.

deviation, nmxillary niidlinr~ to left of n~a~idihul:rr ndline, i 5 ) nl:~nilibular inriwr crowding, (6 ) maxillary right cmine in labiovrrsion, (7 ) l:Ibi:tl inclination of mnxilhyv right ant1 ivft latc~ral incisors ant1 (8 ) rotated maxillary inc,isors. According to Howe’s study model analysis, this case can br considered qurstionablc. Thv canine fossn width mrnsurrd 43 per writ, aud thv interpremolar width measulrd -10 per cent. Since the basal arch width WIS slightly grratrr than the dentnl arch width, exwssive lateral. expansion would not bc rclquiwd, and :I ~rmtlcr.:~tr il~p~~~ of expansiou of thv c~oronal arch width could bc tolerntcd. The interpremolar width of the mantlibuh?r tlcntal arch is quite narrow, for it registered only 36 per cent and is an important consideration in an vv:tluation of the C:IUHC of the incisor crowding. Active treatment time took approximately 26 months. The tt,et,h that were banded were the maxillary and mandibular first molars and incisors. The mandibular incisors xwre banded for only 5 months.

Tandem

Fig. July,

14. Case 1961.

1. Posttreatment

casts

and

concept is, nonextraction

photographs

of

Patient

P. 6. at

treatment

15 years

139

of age.

The patient’s cooperation was excellent, as anticipated. She was seen, on the average, once 3 weeks for adjustment of appliances. The patient vvas under retention for a period of 24 months, and appointments were scheduled at. 2- to 3.month intervals, during which time she wore a maxillary Hawley retainer and a modified mandibular Jackson appliance. every

Case

2 (Figs.

15 and

16)

J. D. was a 13-year-old Caucasian boy. The history and general clinical appearance showed this child to be of good mental and physical health. No allergies or pernicious oral habits were recorded, and he had experienced the usual childhood diseases. The level of cooperation anticipated was very favorable. Photographic evaluation revealed a convex, soft-tissue outline accompanied by a thickened, flaccid lower lip and a taut mentalis band. The remaining facial musculature, however, appeared to be normal in tissue tone.

Fig.

15.

January,

Case

2.

Pretreatment

casts

and

photographs

of

Patient

J. D.

at

13

years

of

age.

1961.

Radiographs revealed ii 101~ caries index. ‘Fhe roots of the maxillary and mandibular canines and premolars were not c*omplrtoly ?lowtl at the apices. Third molar buds were present and wew uormal in size, shape, auti fwpting position. Eruption of the second molars was almost complete, and there was adequate sp:\vin,q betwell the second and third molars. Cast arialysis revealed the following rn:rlrel:ctionsllips: (1) :I (2ass II molar wlationship, more pronounced on the right side, (2) cw:cssiw midline deviation, maxillary midline to the left of the nlxntlihular midline, (3) an anterior overjet of 6 mm., (4) an anterior ovrrbitc of 4 mm., with supraocclusion of the mandibular incisors, (5) labis inclination of mandibular incisors with crowding, (6) insufficient spaw wcommodation for the erupting mandibular second premolar, (7) slight labioversio~~ of the> maxillary right caninr, ( 8) i>ron-ding of

Tandem

Fig. May,

16.

Case

2. Posttreatment

casts

and

concept in nollextracthn

photographs

of

Patient

J. 0. at

treatment

15 years

141

of age.

1963.

maxillary incisors, (9) maxillary right and left lateral incisors lingual to maxillary central incisors, with the left lateral incisor below the maxillary incisxl plane, (10) maxillary right lateral incisor smaller mesiodistally than left lateral incisor. While the nose did not appear excessively long, the family tendency indicated a potential in this direction. Both the interpremolar (39 per cent) and the canine fossa (41 per cent) width measurements indicated that this case was a borderline problem. The apical base was slightly wider than the coronal arch width. To achieve a stable rearrangement of tooth position, lateral expansion must be accompanied by an increase in the width of the basal arch. As in Case I, the mandibular interpremolar width was also 36 per cent. The active treatment phase took 28 months. The patient was seen an average of once every 3 weeks. The only teeth that were banded were the maxillary and mandibular first molars and the maxillary right canine. The retention phase lasted 24 months, and the retainers worn during this period were a maxillary Hawley and a modified mandibular Jackson appliance, Adjustments of these retainers were made, on the average, every 2 to 3 months.

Philip

142

Fig.

17.

Case

December, Care

3 (Figs.

3.

Pretreatment

casts

and

photographs

of

Patient

J. C. at

11

years

of

age.

1961. 17 and

181

J. C., an ll-year-old Caucasian girl, was of Anglo-Saxon ancestry. The general clinical appearance indicated that this patient was healthy, both mentally and physically. History revealed the usual childhood diseases and the presence of a skin allergy. Onset of menarche had not commenced. The patient did not have any pernicious oral habits and expressed :I desire to have her teeth “straightened.” Her brother is presently undergoing orthodontic therapy for a similar type of Class II malocclusion. A photographic evaluation revealed an orthognathic profile with a favorable nosr size. The facial and perioral musculature was normal in tissue tone and the lips, upon contact, were relaxed. Radiographic records showed that, the dcntition of this patient had an average number of simple restorations with some interproximal caries. The maxillary canine and premolar roots were fully developed and the apical portion of the mandibular first. premolar root,s appeared to be arrested in their development. Uneruptetl third molars were present and were of normal size, shape, and erupting positions. The second molars had not erupted. An examination of

Volume Number

68 2

Fig. 18. Case age.

April,

Taylclem co)lcept in ?lo,lextrnctio?l

3. 1964.

Posttreatment

casts

and

photographs

of

Patient

treutme?zt

J. C. at

131/2

years

143

of

the casts showed (1) a Class II molar relationship, (2) a midline deviation, (3) a normal (2 mm.) anterior overjet, (4) an anterior overbite of 4 mm., (5) slight mandibular incisor crowding, (6) insufficient space accommodations for the erupting left mandibular second premolar, (7) labioversion of maxillary right and left canines (mesial shifting of maxillary posterior segments closed space required for canines), and (8) rotated maxillary incisors, with marked rotation of left lateral incisor. The maxillary interpremolar width measurement was 37 per cent and the canine width, 40 per cent. These measurements place this malocclusion into the doubtful category. Lateral growth of the apical base would also be essential in this case. The mandibular interpremolar width was 36 per cent. Active treatment terminated at the end of 29 months. The teeth that were banded were the maxillary and mandibular first molars and the maxillary incisors. The patient was under retention for approximately 24 months. Her cooperation was excellent. A maxillary Hawley

144

Philip

Fig. 19. August,

Case 1960.

4.

Pretreatment

casts

and

photographs

of

Patient

J. G. at

12 years

of

age.

retainer with accessory springs (for the lingual movement, of the maxillary .secontl molars) was worn full time for 12 months, half time for 6 months, and every other night for 6 months. 111 the mandibular arch, a modified Jackson type of retaiuer was worn full time for 12 months, half time for 6 months, and every other night for 6 montlra. Case

4 (Figs.

19 and

20)

J. G. was a E-year-old Caucasian boy of Anglo-Saxon ancestry. The medical history aud general clinical appearance indicated that this child was both mentally and physically healthy. He had experienced the usual childhood diseases and did not have any pernicious oral habits. He was receptive to having orthodontic therapy, and I anticipated an above-average level of cooperation. This patient had a well-balanced facial pattern, with an orthognathic profile, and Ihe circumoral musculature was normal in tissue tone. The lips, upon contact, were in a relaxed state; the nose was normal in size and well oriented to the soft-tissue outline. Radiographs revealed an average number of restorations. The roots of the maxillary and mandibular ranines and premolars were not as yet fully formed. There was a supernumerary tooth between the maxillary right and left central incisors, which was subsequently rcmovcd.

Fig. 20. Case June,

4. Posttreatment

casts

and

photographs

of

Patient

J. G. at

14 years

of

age.

1962.

Third molar buds mere present, with the exception of the maxillary left third molar which was congenitally missing. The remaining third molar buds were of normal size and shape. The mandibular third molar buds, however, did not appear to be in favorable erupting positions. An examination of the study casts revealed (1) :I Class IT molar relationship, (2) a overbite of 5 mm. with midline deviation, (3) an anterior overjet of 4 mm., (4) an anterior a supraocclusion of the mandibular incisors, (5) slight labial inclination of the maxillary right canine, (6) mandibular incisor crowding, (7) the maxillary right central itmisor overlapping the maxillary left, central incisor, and (8) rotation of the maxillary right, lateral incisor. The maxillary interpremolar width measurement was 38 per cent, and the canine fossa width was 44 per cent. In this case, the apical base was sufficient in size to allow a lateral increase in width at the interpremolar area. Severtheleas, the mandibular inter-premolar width, as in the previous cases, was nxrrolv, registering 36 per cent. Active treatment took 23 months, and the patient was seen once every 3 weeks. The maxillary and mandibular first molars and incisors were the only teeth that were banded.

Table

I. Study

model

analysis

of

maxillary

Table

II.

model

analysis

of

mandibular

Study

Total Case No. 1 (P. B.) 2 (CT. D.)

Before 84 88

dental

arch

dental

arch

linecw arch length inclusior of first molars (mm.) After

17ltT+lWW 89 92

5 4

Intercanine Hefore t’s 2x

/

widths dfter

(mm.) Increase

30 29

3 1

3 (J.

C.)

x9

94

5

2i

29

2

4 (J.

U.)

87

91

4

26

28

2

The retention phase lasted 24 months, during which time the patient maa seen an average of every 2 to 3 months. The patient wore :L maxillary Hawley retainer and a modified mandibular Jarkson acrylic appliance. Both retaincw were worn full time for the first year, half time for the next 6 months, and rvrry other night for the remaining 6 months. The patient has been out of retention for a little over 1 ynr. Evaluation

of findings

The linear measurements as depicted in Tables 1 antI 11 show the degree of change that has occurred in both length and width of the dental arches. Of t,he four cases presented in this study, all manifested MI increase in the anteroposterior and mcdiolatcral dimensions of their respective dental arches. The conflncnce of tooth mowments with the concsomitant growth changes that ensued during active treatment c~rcatcd suffkient spac~cfor adequate alignment of the abnormally displacd units into their normal intc~ro~c~lusal and interincisal relationships without atl~rsely affecting the, orthognathic. wntonr of the patient’s facc~. Howes’ diagnostic procedure was supplemcntecl by additional measurements, so that a further comparative cva luation c~ultl be made at the termination of treatment. Cases 1, 3, and 1 registcrctl an 8 mm. increase in the linear length of the maxillary dental arcAh. This incarease was primaril,v the result of the distal movement of the l~uccal scgmcnts ac~companictl by tliminutire changes in the axial positioning of the maxilIar?incisors. 111 (law 2, ~NNYSW-, the increase recordctl was 3 mm. less (5 mm.) ; possibly this may br attributed to the simultaneous dis-

Volume

68

Number

2

Tandem

concept in nonextraction

Canine

(mm.) Intermolar

widths

(mm.) Increase

45 42 43 46

50 51 52 51

53 58 56 58

fossa

(mm.)

widths

_ Before

3 7 4 7

42 40 43 44

Per

cent

After

43 41 40 44

treatment

43 45 49 48

Per cent

Increme

44 46 46 48

1 5 6 4

147

udths inelusive of first molars (mm.) 96 97 105 100

width.3 Interpremolar Before

Per

30 32 35 31

cent 36 36 36 36

widths After 37 35 37 35

Intermolar

(mm.) Per

cent 44 40 38 41

Increase 7 3 2 4

Before 43 44 46 43

widths After 47 51 50 47

inolustie of first molars

(mm.) Increase

(mm.)

4 7 4 4

83 87 95 85

tal movement of the posterior segments and retraction of the maxillary incisors. The mean increase in the linear length of the mandibular dental arch was 4.5 mm., indicating that the necessary anteroposterior changes brought about were ample but not excessive for the realignment of the mandibular teeth. Cases 1, 2, and 4 showed a mean increase of 2.6 mm. in the maxillary intercanine width areas, whereas in Case 3 the increase was almost twice this measurement (5 mm.), an increase which was a definite requirement for the proper positioning of the labially positioned maxillary canines. In the mandibular arch, the mean increase in the intercanine width was 2 mm., indicating that widening of the dental arch in this area was at a minimum. In each case presented, the amount of the increase recorded in the maxillary inter-first-premolar arch width was sufficient to establish a balance between arch width and the summation of the mesiodistal width of the teeth anterior to the second molars. The interpremolar measurement formulated by Howes to represent this balance is 43 per cent. Case 1 shows a change from 40 to 45 per cent, Case 2 from 39 to 42 per cent, Case 3 from 37 to 43 per cent, and Case 4 from 38 to 46 per cent. Increases in the canine fossa widths were also registered. Case 1 showed an increase from 43 to 44 per cent, Case 2 from 41 to 46 per cent, Case 3 from 40 to 46 per cent, and Case 4 from 44 to 48 per cent. These desired changes in the canine fossa area signify that a favorable relationship between the widths of the coronal arch and of the apical base had been established. An attempt to assess, qualitatively and quantitatively, which factors were responsible for the increase

in the size of the apiczal base wonltl 1~ rather tlifiicult to ascel*taill a11t1 is 1101 within the scope of this article. ‘I’r(~atmoni may ha\-(~(*rc~tr~l a f;t vorabl~~rhnvirollrrcnt whcrch;v the maxillar,v basal arch was able to c+ontitllle its inhclrrnt ~rc~\vtll pattern. The intcrpremolar width of the mandibular arch in (~‘ase1 incrt~asctl in siz:ci by 7 mm., approximately twice the amount, registered for (Yases2, 3. and 1. This was to be expected, since the mechanics involved for expansion in this case were morr pronouncctl. Each case also shows an incarease in the intermolar hvitlths of both the maxillary and mandibular dental arches. It is interesting to note that the change recortletl is almost, identical between the maxillary and mandibular dental arches, with the exception of Case 4. The maxillary intcrmolar width in this case increasctl by 7 mm. and the mandibular intermolar width by 1 mm. The distal movement of the maxillary first molars, inherent growth, ant1 the treadmill therapy induced by the inclined plane action accounted for this increase. A cephalometrir tracing of each patient was matte at the completion of active therapy for two reasons: (1) to determine the effect thtb anteropostcrior changes in tooth position hacl upon the relative position of the maxillary ant1 mandibular incisors and (2) to see if the orthognathic integumental profile. as viewed clinically, was any reflection of a favorable skeletal pattern. The linear and angular measurenlcnts that WCYCntilized to arrive at this evaluation w’rrc based upon the norms established by Steiner, Holdaway, and Ricketts. Essentially, all a.bbreriatccl form of Steiner’s ccphalometric analysis was used for this purpose. The norms rcfcrrtvl IO ww as follows: SNA--82 degrees SNB--80 degrees SNI)-76 to 77 degrees ANB-2 degrees l-NA-22 degrees i-NA-4 mm. I-‘()-NB-4 mm. i-NB-25 degrees I-NB-4 mm. 1-i-131 degrees soft-tissue line-KB-approximately 7 to 9 degrees l-APO-minus 2 mm. to plus 3 mm. t-APO-15 to 26 degrees Holdaway, according to Steiner, “believes that ideally t,he measurement pogonion to line NB and the measurement of the lower one to line NB should be equal (1:l ratio) .“li A 2 to 3 mm. variance can be tolerated, depending upon the thickness of the soft-tissue outline. If the angle formed between the hardtissue line Tu’B and a line drawn tangent to the chin and upper lip is 7 to 9 degrees, the facial contour is favorable. Ricketts is of the opinion that the lower incisor should be oriented to both denture bases. The plane of reference that he uses for this purpose is the APO plane. The acceptable range that he has established for the position of the lower

Volume Number

68 2

Tandem concept in nonextraction

case

treatment

1. 413164.

SNA-83 SNB-78 SND-76 AN&S L--NA-3.5 I-NA-14 i-NB-5 i-NB-25 Po-Nkl.5 -l-

degress degrees degrees

degrees mm. degrees mm. degrees mm. -1 37 deg.rees

i

-APO-2.5

mm.

-APO-23

degrees

i i Soft-tissue lin+NB-9.5 Above average soft-tissue

Fig.

21.

Case

1, Patient

P. 6.

degrees thickness

149

150

Philip

incisor is minus 2 to plus 3 mni. ahratl of the AI’0 plant at 15 to 26 dcpr.cc~ I Its directs his treatment objectives according to this rangc.2i’ (‘use 2 (Fi2iTig. 21). The maxillary (lenturc base is rclatrtl normally to the critilial anatomy (SNA, X3 degrees), and the mantlibular clcmtuw base is slightly distal to the cranial anatomy (SNB, 78 tlrgrecs). The same degree of discrepancy holds for the relationship of the denture bnsrx to each other ( I\NB, 5 degrees). ilccorcling to the SND (76 degrees) reading, the mandible is in a favorable position, indicating that the skeletal pattern as a whole is favoral)lc. The denture analysis reveals a large intcrincisal angle (137 tlegrccs) which is primarily attributed to the axial position of the maxillary incisors (1 - NA, 14 degrees). The linear measurement of the maxillary incisors corresponds closely to the established norm (1 - NA, 8.5 mm.). The axial and linear position of the mandibular incisors to the NB plant is normal (7 SB, 5 mm.; NB, 2.5 degrees). Pogonion to the NB plane is 1.5 mm., thus making the Holdaway ratio 5 :l.Fi. Considering the thickness of the soft-tissue outline, this 3.5 mm. variance is tolerable. The short distance of pogonion to the NB plane is due to a small chin button. The angular measurement I)etw-ccn the soft-tissue line and the 3iB plane registered 9.5 degrees and was within Holdaway’s range of acceptance. The position of the mandibular incisor, according to Richetts’ evaluation, is 2.5 mm. from the APO plane and axially 23 degrees to this same plane. These measurements further indicate that the mandibular incisor is in a normal position. CGYX% (Fig. 22). The skrlrtal analysis places both denture bases posterior to the cranial anatomy, the mandibular more than the maxillary (SNA, 76 degrees ; SNB, 69 degrees ; and SND, 68 degrees). Relating the denture bases to each other, the mandibular is posterior to the maxillary base (AKB, 7 degrees). The denture part of the analysis indicates that the interincisal angle value is normal (131 degrees). This was due to an upright position of the maxillary incisors and a labial inclination of the mandibular incisor ( 1 - NA, ‘L mm. ; I -- NA, 14 degrees ; 7 - NB, 7 mm. ; i - &B, 28 degrees). Pogonion to the NB plane is t! mm. and is indicative of an underdeveloped sgmphysis. The IIoldaway ratio is 7 :I?, and the 5 mm. varia.nce is beyond the tolerable limits established by Holdaway. The soft-tissue line to the NB plane is 12 degrees. I)espite these unfavorable readings, the patient, as viewed clinically, has a well-balanced facial contour. The component parts of the soft-tissue outline are harmoniously oriented to one another. In applying Ricketts’ method of evaluation, the mandibular incisor to the APO plane falls within his acceptable range (i- APO, 2.5 mm.; 1 - APo, 23 clegrees). Cn,se 3 (Pi.r/. 23). Although the denture bases are related normally to each other, they have not yet fully migrated from under their cranial base (SNA, 76 degrees; SNB, 76 degrees; SND, 74 degrees; and ANB, 0 degrees). The skeletal pattern appears to br rct,rognathic, whereas the facial contour is orthognathic. In the denture part of the analysis, the interincisal angle approximated the norm ( 130 degrees). The axial and linear positions of both the maxillary and

i --

case 2. 2120164. SNA-76 degrees SNB-69 degrees SND-68 degrees AN57 degrees I-NA-14 degrees 1-NA-2 mm. i-N&7 i-NB-28 Po-N&2

mm. degrees mm. -1 31 degrees

li

i Soft-tissue line--NB-12 Above average soft-tissue

Fig.

22.

Case

2, Patient

J. D.

degrees thickness

Case 3. SNA-76 SNB-76 SND-74 AN50 1_NA-6 1_NA-29

7/20/65. degrees degrees degrees degree mm. degrees

T-NB-3 i--N&21 PO-N&2.5 l-

mm. degrees mm. -130 degrees

i -APO-~

mm.

i -APO-23

degrees

i krft-tissue Average

Fig.

23.

Case

3, Patient

J. C.

line-N&S soft-tissue

degvees thickness

Ta?tdenz come@ iw wmextraction

treatment

153

mandibular incisors are well oriented to their respective planes (1 - NA, 6 mm. ; I - NA, 29 degrees; 3 - NB, 3 mm.; and i - NB, 21 degrees). - The mandibular incisor is ideally related to PO and the NB plane, since the Holdawax ratio is 1 :l. Its axial and linear relation to the APO plane is also normal (1 - APO, 2 mm. ; 7 - APO, 23 degrees). In this case, the chin button is well developed. The soft tissue is average in thickness, and the soft-tissue line to the NB plane is 5 degrees which may be due to a slightly retruded upper lip. Case 4 (Pig. 24). The maxillary and mandibular denture bases are normally related to the cranial anatomy and to each other (SNA, 80 degrees; SNB, ‘79 degrees ; SND, 78 degrees; and ANB, 1 degree). The interincisal angle in the denture part of the analysis is large (139 degrees). Although the axial and linear positions of the maxillary incisors are normally related to the NA plane -- (1, 24 degrees; 1 - NA, 4 mm.), the mandibular incisors are too upright (1 - NB, 16 degrees) in their axial positions. Linearly, the relationship of the mandibular incisors to the NB plane falls within the range prescribed (7 - NB, 3 mm.). Lingual root torquing of the mandibular incisors would have improved their axial position. Because of the nature of the appliances used, this type of movement could not have been accomplished. Pogonion to the NB plane is 5 mm. The patient has a well-developed mandibular symphysis. The mandibular incisors are 3 mm. anterior to the NB plane, making the Holdaway ratio 1:2. According to Ricketts’ evaluation, the mandibular incisors are also in a favorable relationship to the APO plane (~-APO, 0 mm. ; ~-APO, 20 degrees). The soft-tissue line to the NB plane is 9 degrees, indicating that the integumental profile is favorable. Summary

1. A systematic controlled nonextraction approach in the treatment of certain Class II malocclusions exhibiting arch-length deficiencies has been presented. 2. Clinical cases, diagnostic criteria for case selection, the biomechanics of this tandem force system, time sequence in tooth movement, and ways to avoid untoward sequelae have also been offered. 3. The major advantages in utilizing the basic extraoral appliance and auxiliary mechanisms are as follows : A. various groups of tooth movements are initiated in one or more areas of both dental arches simultaneously. B. Orthodontic pressures are within physiologic limits. C. A minimum number of bands is required. D. Positive control of anchorage is ensured. E. Class II mechanics is not necessary. 4. In each of the four cases presented, the anteroposterior and mediolateral changes that occurred resulted in an increase in the linear length and width of the maxillary and mandibular dental arches. A sufficient increase in the maxillary apical base was also noted and may prove to be a significant yardstick in measuring the stability index of each case.

154

l’hilip

Ca’se

SNA-80 SNB-79 SND-78 ANB-1 l-NA-4

4. 8 / 17165. degrees degrees degrees degree mm.

i-NA-24 i-NB-3

degrees mm.

T-N51 Po-NBS li -APO-O

6 degrees mm. -1 39 degrees mm.

i -APO-20 i Soft-tissue Average

Fig.

24.

Case

4,

Patient

J. G.

degrees line-N&9 soft-tissue

degrees thickness

5. Photographic and cephalomctric evaluation tour and the relative position of the mandibular affected.

revealed that the facial conincisors were not adversely

Conclusions

With normal growth factors, proper treatment timing, case selection, appropriate mechanotherapy, and good cooperation from the patient, many more “borderline” eases can be successfully resolved without extraction of premolars. The author wishes to for his wise counsel and specialty of orthodontics.

express guidance

his

grateful appreciat,ion during the author’s

to the formative

late Dr. Irving Grenadier years as a novice in the

REFERENCES

1. Anderson, G. M.: Practical orthodontics, St. Louis, 1955, The C. V. Mosby Company, p. 81. 2. Bjiirk, A.: Mandibular growth and third molar impaction, Acta Odontol. Stand. 14: 231.272, 1956. 3. Brodie, A. G.: Lecture at a scientific meeting of Northeastern Society of Orthodontists, New York, 1965. 4. Burstone, C. J.: Process of maturation and growth prediction, Allr. J. ORTHOD. 49: 967-919, 1963. 5. Carey, C. W.: Diagnosis and case analysis in orthodontia, A&l. J. ORTHOD. 38: 149-161, 1952. orthopedia and prosthetic correction of cleft palate, New York, 1921, 6. Case, C.: Dental Quick Lithographers, Inc., p. 134. 7. Dewel, B. F.: Objectives of mixed dentition treatment in orthodontics, AX J. ORTHOD. 50: 504-520, 1964. 8. Fischer, B. : Orthodontics, Philadelphia, 1952, W. B. Saunders Company, p. xvii. 9. Foresman, R. R.: The maxillary first permanent molar as a rausative factor in arch length deficiency, Angle Orthod. 34: 174.180, 1964. 10. Gould, E. I.: Mechanical principles in extraoral anchorage, AM. J. ORTHOD. 43: 319-333, 1957. 11. Hambleton, R. 8.: The soft-tissue covering of the skeletal face as related to orthodontic problems, AM. J. ORTHOD. 50: 405-420, 1964. 12. Howes, Ashley E.: Model analysis for t,reatment planning, AM. J. ORTHOD. 38: 183.205, 1952. 13. Jarabak, J. R., and Fizzell, J. A.: Technique and treatment with the light wire appliances, St. Louis, 1963, The C. V. Mosby Company, pp. 425427. 14. Jay, J. : Lectures at Columbia University. 15. King, E. W.: Treatment timing and planning in Class JI, Division 1 malocclusions, AM. J. ORTHOD. 50: 4-14, 1964. 16. Kloehn, S. J.: Evaluation of cervical anchorage force in treatment, Angle Orthod. 31: 91-104, 1961. 17. Kraus, B. S., and Riedel, R. A.: Vistas in orthodontics, Philadelphia, 1962, Lea & Febiger, pp. 131-148, 188-195, 227-258. 18. Moore, A. W.: Orthodontic treatment factors in Class II malocclusion, Aai. J. ORTHOD. 48:

323-352,

1959.

19. Oppenheim, A.: Biologic orthodontic t-herapy and reality, Angle Ortllod. 1936. 26. R.ieketts, R. M. : Keystone triad, Ahr. J. ORTHOD. 50: 72%750, 1964. 21. Sxlzmann, J. A.: Orthodontics, practice and technics, Philadelphia, 1957, Company, vol. 2, pp. 86-92, 103-104, 296-298, 375.

6:

69, 116,

J. B. Lippincott

163,

‘)‘)

_I.

23. 24. 25. 26. 27.

Schwab, I). T. : E:xtraction elf&s on the rlenial profile in hordwline cases, r\nglc Orthod. 33: 120.122, 1963. Sillman, .J. H. : Uimensional Chnnges of the Dental Arches : Longitudinal Study From Birth to 25 years, Anr. ,J. ORTHOD. 50: 82-t-841, 1964. Subtelny, J. I).: The soft tiswuc profile, growth rind trr:1tmcnt changes, Angle Orttlotl. 31: 165-l”2 1961 . . Van Nat&’ R., and Rambha, J. K.: Longitudinal study of facial growth in relation to skeletal maturation during adolescence, AM. J. OKTHOI). 49: 4X1-493, 1963. Weislander, T. : The effect of orthodontic treatment on the concurrent, development of the cranofacial complex, AM. J. ORTIIOD. 49: 15-27, 1963. Wilson, IV. L.: The development of :I treatment plan in the light, of one’s concept of treatment objectives, Au. .J. ORTHW. 45: 561-573, 1959. 4.915 HI-orlazofly

THE JOURNAL 60 YEARS AGO August, The

point

1915 I want

to

call

attention

to

is,

that

in

the

normal

development

of

the

lower

jaw, the growth seems to be chiefly at the posterior edge of the ramus, at the posterior border of the coronoid process, at the epiphyses of the condyle, on the surface and borders of the body. Concomitant with the growth of bone on the posterior border of the ramus, you have an absorption on the anterior border of the ramus and the anterior border of the neck which allows the ramus to march backward or the body forward, and gives length to the body of the jaw bone. Now, the position of the original deciduous molars is occupied eventually by the premolars which require much less space than the molars. That extra space which was occupied by the molars is supposed to be taken up in the adult jaw by the greater width of the cuspids, these being pushed backward, and also by the molars traveling forward. In a lower jaw in which the body is of a length corresponding to the space required for the teeth, as the deciduous molars are cast off and the permanent erupt, there is a movement of the cuspids backward and of the molars forward, by which the premolar space is filled up. Just for the sake of argument, if you will grant that an individual, through heredity or any other way you choose to put it, would develop a body of the jaw bone that was larger than was necessary for the teeth which it is to contain, then it would not be necessary for the cuspids to move distally, nor the molars mesially; they would find room without migration. (Vilray P. Blair: Instances of Operative Correction of Mal-Relation of the Jaws, 397-398.)