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A Classification of Mutilated Dental Arches Requiring Treatment by Removable Partial Dentures
THE J O U R N A L of the
AMERICAN DENTAL ASSOCIATION V o l. 29
D E C E M B E R 1, 1942
N o. 19
A CLASSIFICATION OF MUTILATED DENTAL ARCHES REQUIRING TREATMENT BY REMOVABLE PARTIAL DENTURES B y E d w in H . M
auk
, D .D .S ., Berkeley, C alif.
N Y consideration o f rep arative den tistry m ust start w ith the ideal or standard o f tw o u nbroken dental arches o f sixteen teeth e a c h ; the low er a ctivated b y the muscles o f m astication attach ed to the m andible, the tw o to gether aided b y the cheeks, th e tongue and the lips perfo rm in g the fu n ction o f tritu ratin g food and m ixin g it w ith saliva to prep are it fo r d e g lu titio n ; i.e., m asti cation. W h ile m astication o f foo d is no doubt the m ost im portant fu n ctio n o f the teeth and jaw s, it m ust be noted th at th ey fu l fil other essential physiologic purposes as w ell. T h e y aid in deglu tition an d they h ave an im portant part in th e production o f s p e e c h ; and it is w ell understood that good appearance is largely dependent on the presence o f a fu ll set o f teeth in such alin em en t as to m ain tain correct and pleasing relations o f the low er third o f the fa ce to the head as a w hole.
A
Read before the Section on Partial Denture Prosthesis at the Eighty-Third Annual M eet ing of the American Dental Association, Hous ton, Texas, October 27 , 19 4 1 . Jour. A .D .A ., Vol. 29, December 1, 1942
F o r the m ain tenance o f these fu n c tions at their highest efficiency, each m em ber o f the arch m ust ( 1 ) h ave u n broken contours and (2) be in lateral con tact w ith its contiguous mem bers. I t w ill b e noted th a t this fa c t conform s to the physical law s govern in g the use o f the arch in various phases o f architecture. Som e authorities term the com pleted dentition w ith its surrounding oral parts an organ, just as w e refer to oth er organs in the body, because o f the ve ry im por tan t role the den tal equipm ent has to p la y in the ph ysiologic processes of the entire system .1’ 2 W h en ever the arch b e comes m u tilated b y losing some o f its m em bers, i.e. w hen teeth are extracted, the m asticatin g fu n ction is im paired in proportion to the num ber o f lost m em bers as w ell as the position th at th ey o c cupied in the arch. T h e initial b reak in arch con tin u ity is follow ed b y a w hole train o f d en tal evils. It is com m on know ledge th a t the teeth on each side o f the break, w hen deprived o f th eir lateral contact, strongly tend to rotate, to tip into the space and to b e 2121
212 2
T h e J o u r n a l o f t h e A m e r ic a n D e n t a l A s s o c ia t io n
com e loosened. D estru ction o f the p eri d en tal m em brane follow s, w ith serious derangem ent o f the occlusion. U nless a rem ed y is applied b y m eans o f repair or b y reconstruction, th e condition m ay rap id ly progress to com plete disintegra tion o f the entire d ental arch , finally necessitating the rem oval o f a ll the teeth com posing it. I t is true th at third m olars can be rem oved from the ad u lt d en tal arch and the continuity o f the rem ain ing mem bers b e un affected an d fu n ction unim paired, an d also th at the loss o f a single tooth from the arch of a y o u n g person m ay often be com pensated fo r by the m oving o f other teeth to close the gap , although
Fig. I.— Types omitted from classification. Anchorage for retention being insufficient, par tial dentures tend to convert the conditions rapidly into full denture cases.
this is questioned b y som e authorities. A lm ost all other cases o f m u tilation of the a rch call for a m ore constructive rem edy in the form o f a so-called p a rtial denture, either fixed or rem ovable. T h e A m erican D en ta l Association, it is approp riate to note here, has m ade a ru lin g in recent years th a t a section of th e organization know n as th e Section on P artial D en tu re Prosthesis shall devote itself to the discussion o f a ll form s o f d en tal restorations o f m ore than one tooth and less than th e entire arch w h eth er th ey be fixed or rem ovable. D e n
tal teachers and w riters on this su b ject h a ve agreed th a t it is alm ost im possible to establish a distinct line o f dem arcation in d efin ing a partial denture a n d a re m ovable bridge. In general, an a p p li ance h a v in g saddles together w ith con n ectin g bars and clasps is referred to as a p a rtial denture or, m ore prop erly, a rem ovable p a rtial denture. S im ilar restorations h a vin g precision attachm ents fittin g into crowns o r inlays in th e abu t m ent teeth are p o p u larly term ed rem ov able bridges. T h is discussion w ill deal exclu sively w ith the p artial rem ovable d enture or partial plate d en tu re type. T h e fixed and rem ovable bridge types,
Fig. 2 .— Types omitted from classification because infrequent. The usual means of treat ment is more in the nature of a cantilever bridge than a partial denture of the type under discussion.
together w ith designs for the restorations them selves, w ill be om itted ex cep t for co llateral reference. In fo llo w in g accepted m odern p ractice in m ed ical and d ental science, w h ich de m ands a detailed diagnosis based on all the availab le facts w h ich can serve as a gu id e in form u latin g the specifications o f th e rem ed y to be applied, it becom es necessary to h ave a classification o f cases th a t w ill id en tify the outstanding types w ith o u t recourse to a cum bersom e toothb y-tooth and space-by-space description, and, i f possible, to include some o f their
M
auk
— M
u t il a t e d
features. (“ A p lan of treatm ent should fo llo w and b e dictated b y a diagnosis, and can b y no stretch o f the im agina tion take the place o f it.” 3) F o r the purpose o f classification, w e need not consider the pathologic condi tions th a t cause a break in the arch b y the loss o f teeth, because all pathosis has presum ably b een elim inated b y the e x traction w h ich creates the space.
Fig. 3 .— T ype with short spaces not class ified separately, although included in main groups. T he restorative means takes the form of a bridge.
D
ental
A
rches
2123
position o f the rem aining teeth. A ctu a lly , these are the conditions th a t lim it the usefulness o f a n y appliance fabricated fo r rem ed ying the deficiency. I t m a y be regarded as axio m atic th at the m asticat in g fu n ction w h ich can be considered restorable is in direct proportion to the num ber o f rem ain ing teeth. Im m ediately a classification is a t tem pted a lo n g this line, i.e. the spaces existin g in the arch, tw o form idable diffi culties arise. O n e is the m athem atical m agn itu d e o f possible com binations. B e gin n in g w ith the loss o f one tooth, and progressing to the com plete destruction o f one arch o f sixteen members, this runs into m an y thousands as com puted by C u m m er, w ho says th at “ in either the
Fig. 4 .— Cases, with relatively long spaces compared to those of Figure 3 , classified as requiring partial dentures, which afford sup port and lateral bracing effect not obtainable by means of bridges. Fig. 6 .— Partial denture as advertised, an example of mechanical design disregarding functional needs. It lacks effective support.
Fig. 5 .— T ype included in classification be cause either partial denture or bridges may be means of treatment. (Compare description of Class 6 .)
O b viou sly, then, in m utilated arches, the m ain factors to be classified are the ph ysical conditions. T hese consist o f (1) the num ber, len gth and position of the spaces, w h ich offer the m ost apparent evidence o f im paired fu n ction o f the den tal organs, and (2) the n um ber and
u p p er or low er jaw , there can be 65,536 cases.” 4 E xcep t fo r statistical purposes, such a classification w ould be virtu a lly useless. Its m an ifold com plexities w ou ld p rohib it a n y fu rth er consideration o f its application in den tal p ractice as a basis fo r grou p in g sim ilar cases that occur fre quently. T h e other difficulty, th at o f m akin g a classification sufficiently lim ited to com e w ith in the range o f usefulness, in evitab ly results in a com prom ise b y om ittin g some com binations th at are o c casionally observed. T h e re is a w ell-established precedent fo r such a com prom ise, n otably the B lack
2124
T h e J o u r n a l o f t h e A m e r ic a n D e n t a l A s s o c ia t io n
classification o f tooth cavities, w h ich does n ot include all cavities occu rrin g on all tooth surfaces. It is h ig h ly significant that, in spite o f these omissions, the B lack c a v ity classification has com e into alm ost universal use in the field o f opera tive dentistry and has stood the test o f usage over a lon g period of tim e. M o re over, some o f the possible com binations o f spaces and teeth rem ain ing in the arch a re such th a t a p artial denture w ould b e inefficient o r w ou ld tend to cause early rem oval o f thé teeth th at are in position. T h ese cases should b e regarded as tem p o rarily deferred fu ll denture cases,
classification, as in the instance o f the B lack c a v ity classification. (Fig. 2.) A th ird grou p presents short spaces for w h ich bridgew ork, eith er fixed or o f the rem ovable type, is unm istakably th e best rem edy. T h erefo re , it is n ot necessary to in clu d e this grou p as a separate class in a classification o f cases w h erein re m ovable p artial dentures are indicated.
F ig . 7.— L a r g e s t c la ssific a tio n g r o u p , id e n ti fie d b y b ila te r a l sp a ce s w it h n o te e th p o s te rio r to th em . A p a r t ia l d e n tu re w ill b e la r g e ly tissu e b o rn e . T h e re sto ra b le fu n c tio n is q u ite lim ite d .
Fig. 9 .— Bilateral spaces with posterior tooth support available on both sides. The restor able function is relatively greater than in other types, except Class 6 , if spaces are of moderate length.
Fig. 8 .— Posterior spaces, bilateral. Posterior tooth support is available on one side. The restorable function is greater than in Class 1 .
Fig. 10 .— Unilateral space, very unfavorable for restoration of masticating function, al though remaining teeth compensate unless interjaw relation is similar to that shown here. Secondary functions, i.e. aid in speech and appearance plus maintenance of vertical jaw relations, are almost w holly restorable.
therefore it is n ot necessary to inclu d e them in a p a rtial denture classification. (F ig. 1.) In th e accom p an yin g series o f draw ings, only typical instances have b een selected fo r illustration am ong all the com binations th a t m ay occu r in the class indicated. W id e latitu d e exists w ith in each class fo r v a riatio n s; th at is to say, the classification is flexible. A second group o f com binations pos sible in eith er arch occu r so infreq u en tly as to be o f quite m inor im portance and can be safely disregarded in a w orking
(Fig- 3 -) H o w ever, this grou p m erges in to those h a vin g m u ch longer spaces. I t is only necessary to regard the spaces in F igu re 3 as b ein g considerably increased b y the fu rth er loss o f teeth, w h ereu p on the con-
ditions th a t lo gically require p a rtial d en tures o f a rem ovable type readily becom e apparen t. (F ig. 4.) T h erefo re all these groups are included in the m ajo r classes shown later. A fo u rth grou p , h avin g m u ltiple short spaces, com prises cases w herein either b rid gew ork o r a rem ovable p artial d en ture can b e used as the rem edy o f choice. T h erefo re, this grou p should b e included
M a u k — M u t il a t e d D e n t a l A r c h e s
2125
in the classification u n der discussion. (F ig. 5.) T h e choice depends on several facts. F requently, it is determ ined b y the condition o f the abu tm ent teeth. I f their crowns are so b a d ly d ecayed th a t they require restoration, suitably b y bridgework, this w ou ld seem to be a decisive fa c t in fa v o r o f bridgew ork as the most desirable means o f treatm ent, provided the peridental attachm ents are in good condition. O n the other hand, if the abutm ent teeth are not carious, oth er facts m ay prove to be conclusively in fa v o r o f treat m ent w ith a rem ovable partial denture. T h e patien t m a y justifiably ob ject to the cu ttin g o f sound tooth surfaces, either from d read o f the w ea r and tear on the nervous system or from a fea r of losing the teeth due to some previous u n fortu nate experience w ith crowns.
brid gew ork h a vin g been elim inated as outlined above, the rem ain ing cases can n ow be grou p ed u n der a triad com prising all the features w h ich it is essen tial to recogn ize in a classification o f this kind, as fo llo w s : 1. F re q u e n cy o f occurrence, w h ich w ou ld in d icate the num erical order o f each class. 2. Position and extent o f the space or spaces in the arch, w h ich w ou ld in d icate the type o f applian ce to be fabricated to rem ed y the m utilation. 3. T h e exten t o f support availab le in the form o f rem ain ing teeth a t the ends o f spaces, w h ich w ou ld ind icate the am ount o f fun ction, especially m asticat in g fun ction, th a t it is possible to restore b y m eans o f the applian ce used. B y m akin g this approach to the p ro b lem , th a t is, an approach from the bio-
Fig. 1 1 .— Single anterior space. The class ification is unaffected by the absence of third molars. The case is favorable only for restora tion of the secondary phases of function.
Fig. 12 .— Irregular spaces around entire arch, favorable for restoration of function un less peridental attachments are badly impaired.
U n d e r these conditions, the use o f a p artial denture w ou ld avoid the form id able cu ttin g n eeded fo r bridge a tta ch ments. T h e resultant econ om y o f both ch air and laboratory tim e w ou ld perm it a low er fee, w h ich in itself is a n im por tan t fa cto r in m an y cases. F in ally, a n oth er fa c t m ay determ ine the c h o ic e : I f the peridental attach m ents o f the abu tm ent teeth are m u ch im paired, a partial denture w ith its conn ectin g bar w ill h a ve the ad va n ta ge o f a b racin g effect across or aroun d th e arch, actin g as a splint, w h ich w ou ld not be the case w ith b ridgew ork in tw o or m ore separate pieces. T h e cases th at m a y be term ed deferred fu ll denture cases, the cases th a t occur in freq u en tly and the cases requiring
logic o r ph ysiologic standpoint o f im paired fu n ctio n o f an organ, the possi bilities o f the attem p t to com pensate fo r lost fu n ction b y the use o f an appliance, and also its definite lim itations, w ill be better understood. D esigns for the v a ri ous types o f cases w ill then develop w ith this consideration, fu n ctio n al efficiency, as the m ost im portan t essential. I f the a p proach is m ad e from the engineering standpoint prim arily, the resulting ten d en cy in design is to stress m echanical d e tails and thus to prod u ce refined m ech anisms th at m a y fa ll fa r short o f effi cien cy in function. F o r instance, a rem ovable p artial d en ture is som etim es m ade to supply a ll o f the u p p er teeth b ack o f the cuspids, h a v ing v e ry n arro w saddles and w ith a light
2 12 6
T h e J o u r n a l o f t h e A m e r ic a n D e n t a l A s s o c ia t io n
skeleton fram e across the v a u lt and a rou n d the lin gu al aspect o f the anterior teeth. (Fig. 6.) T h is is a n exam ple o f m ech an ical refinem ent d eveloped per haps in response to the usiial dem and of th e patien t fo r lightness, fo r m inim um b u lk, leavin g the v a u lt open, and fo r a general appearan ce sim ilar to th a t o f fine jew elry. S uch a restoration, though it m a y please the patien t at first, lacks th e essential feature fo r go od fu n ctio n ; th a t is, a broad bearin g a rea on soft tis sues, since there are n o posterior teeth fo r support. C on seq u ently, the denture fails to resist m asticatin g stress suffi ciently, settles ra p id ly ou t o f occlusal con tact and loosens the abu tm en t' teeth prem aturely. A base w ith va u lt cover age, either in fu ll or in p art, w ou ld be m u ch better ad ap ted to m eet the de m ands o f m astication in this case. T h e classification given later was evolved b y a p p ly in g the foregoin g prin ciples to a collection am ou n tin g to about 1,000 m odels accu m u lated in th e pros thetic infirm ary over a period o f years w ith this ob ject in view . R ep ea ted p re lim in ary sortings and groupings elim inated ( i ) the in freq u en t cases; (2) the cases in w h ich p artial dentures w ere im practical because too fe w teeth rem ained fo r ad equate reten tio n ; (3) the cases in w h ich rem oval o f a considerable num ber o f teeth, com prising a ll those rem aining in the arch, was im m in en t because of periden tal destruction, and (4) thè cases in w h ich brid gew ork w as obviously the m ost desirable m eans o f treatm en t be cause o f the short spaces existing. T h is le ft about 600 m odels, m ore than one th ird o f the origin al n um ber h a vin g thus been set aside. T h is rem ain ing n u m ber was re arran ged in six groups, w h ich w ill be described. A critical and extend ed study w as m ade o f this arran gem en t to test its a p plicatio n to clin ical p ra ctice and its c a p a c ity to includ e a ll cases in w h ich p a rtial dentures h a d b een successful. T h is stud y finally led to th e conclusion th at this lim ited selection w o u ld repre
sent n ea rly o r qu ite a ll those cases in w h ich p a rtial denture construction w ou ld be feasible as th ey com e into the hands o f the general practitioner. In short, a w orkable classification o f com parative sim plicity fo r d ay-in and d ay-ou t needs ha d b een gra d u ally form u lated in h a r m on y w ith the three features en um er ated. T h is w as lack in g in m ath em atical and statistical com pleteness, as m igh t be exp ected , b u t it em bodied an inh erent fa c ility fo r id en tifyin g and com parin g the con stan tly recu rring cases so th a t the resultant design could be evolved lo g ic a lly acco rd in g to m inor differences am on g cases in the same class. T h is classification w as ten tatively ad opted fo r classroom an d clin ical w ork abou t 1926, continuing to d a te.* I t has proved a valu ab le aid in teach in g and in keep ing records. L a te r adopted b y g ra d uates fo r office practice, it is com in g into m ore gen eral use b y the profession. A ll p ractical and statistical observations seem to in d icate th at it is sufficient fo r general needs. I t is hoped that, like the B la ck c a v ity classification, because o f its sim plicity and its a bility to describe the conditions th at it classifies, it w ill w ith stand th e test o f tim e and extended usage. T h e separate groups com prising the classification are as fo llo w s : C lass 1 : B ilateral posterior spaces, rem ain in g teeth in a segm ent in the anterior area.
43211123
(F ig. 7, A )
321|1234
(F ig. 7, B)
Class 2 : B ilateral posterior spaces, one or m ore teeth a t the posterior o f one space. 87 43211123 (F ig. 8, A ) (F ig. 8, B )
54321(1234 78
C lass 3 : B ilateral posterior spaces, one or m ore teeth a t the posterior o f both spaces. 8 3211123 8 (F ig. 9, A )
87
32111234
8
(F ig. 9, B )
•U niversity of California, School o f Den tistry.
M a u k — M u t il a t e d D e n t a l A r c h e s
Glass 4 : A unilateral posterior space, with or without teeth at the posterior of the space, the arch unbroken at the op posite side. 87654321|123
(Fig. 10, A)
4321112345678
(Fig. 10, B)
Class 5 : Anterior space only, posterior part of the arch unbroken on either side. 7654 | 345678 (Fig. 11 , A) 87654 | 345678 (Fig. 11 , B) Class 6 : Irregular spaces around the arch, remaining teeth single or in small groups. 8 6 4 21| 3 5 7 (Fig. 12, A) 8 65 3 | 3 67 (Fig. 12, B) t h e f ir s t c l a s s
(t a b u l a t io n )
The teeth in the anterior region usu ally number six to ten. They m ay be in equalor unequal arrangement on each side of the median line, with a strong tendency for this arrangement to be sym metrical. Nearly all writers on this subject seem to note this type as occurring more fre quently than any other, and to mention it first in efforts to classify their cases, but do not cite any statistical facts .5 This group, perhaps better than any o f the others classified, permits the appli cation of the triad of features enumer ated, which stand out as demanding recognition in the plan o f classification. T h e First Feature. — Numerical fre quency, about 45 per cent, is strikingly apparent in the tabulation given here with, which logically therefore gives this type first place as a class in accordance with the triad. T h e S econ d Feature. — T he spaces, bilateral and posterior, indicate that the restoration will necessarily have to be one depending very largely on the soft tissues for support in mastication. This cannot be otherwise, since the remaining teeth can furnish only a limited part of the support necessary because of their anterior position out of the main area of mastication.
2127
T h e T h ird Feature.— T h e am ount o f fu n ction restorable is closely related to the second featu re. O w in g to absence of posterior tooth-bearing, fu n ctio n can be restored to o n ly a lim ited degree. T h e fu n ction o f th e n atural teeth in the pos terior areas is m ain ly m astication. T h e y h ave b u t little to do w ith the fu n c tion o f speech, b u t th ey are the teeth that, m ore th a n a n y other p a rt of th e dentition, h a ve the im portant secondary fu n ction o f m ain tain in g the vertical relations b etw een the jaw s. T h is type o f p artial d en tu re can not ad eq u a tely m eet the dem ands o f m asticatin g efficiency because the tissues w h ich h a ve to support it can b ear o n ly a fractio n al p a rt o f the a vailab le m u scu lar fo rce w ith ou t severe pain and perm anent in ju ry. F o r sim ilar reasons, the attem pts th at are m ad e to restore and m ain tain vertical in terjaw space w ith this kin d o f denture are sub je c t to the sam e cause o f failu re, as it is fou n d th a t th e supporting tissues resorb too ra p id ly u n d er these conditions to preserve the space fo r w h ich the a p p li ance is designed. T h u s, the condition m a y b e sum m ed up b y saying th a t w hile this grou p co m prises alm ost h a lf o f all p artial denture cases, the p a rtial denture used in its trea t m en t is u n fo rtu n a tely the least efficient o f all types in restoring fun ction, alth ou g h ' it m a y be v e ry successful as regards com fort and satisfaction to the patien t w hen the a p p lian ce is p rop erly designed and executed. t h e se c o n d c l a s s
T h e second class occurs m u ch less fre q u en tly th an the first, alth ou gh it does inclu d e a w id e va riatio n in the n um ber o f rem ain ing teeth and their location in th e arch. T h e r e is less tend en cy fo r an equal n u m ber o f teeth to be le ft on each side o f the m ed ian lin e ; in fa ct, it is usual to find a short space on one side and a lon g space on the other. T h e T y p e o f A p p lia n ce In d ica ted .— T h e ap p lian ce indicated is one dep en d in g entirely, o r n ea rly so, on tooth sup
212 8
T h e J o u r n a l o f t h e A m e r ic a n D e n t a l A s s o c ia t io n
p o rt on one side o f the arch, the oth er side d erivin g its support to a great extent fro m the u n derlyin g m ucous tissue espe c ia lly in the u p p er arch. T h e F unctiori R estorable.— T h e possi bilities o f restoring fu n ctio n are m u ch better th an in the first class ow in g to th e fa c t th at m ore positive support is a vailab le a t both ends of one space. I t is fou n d , as m igh t b e expected, th a t this side o f the applian ce is h a b itu ally used b y the patien t fo r ch ew in g efficiently and com fo rta b ly rath er th an the opposite or A
Class 1
2
3 4 5
6
ve ry frequent. In distinction fro m Glass i and C lass 2, the prosthetic treatm ent fo r it is essentially bridgew ork, since there is tooth support availab le a t both ends o f a ll spaces. I t m ust b e evid ent that, in this class o f case, there can b e no clear line o f dem arcation betw een rem ov able brid gew ork and so-called p artial dentures. T h e restoration m a y be eith er fixed b ridgew ork, rem ovable brid gew ork h a v in g precision attachm ents fo r retention and support or a n appliance th a t is in
S u r v e y o f P a r t ia l D e n t u r e C a s e s *
Teeth
Proportion Upper to Lower
Class Total
Approximate Per Cent
1
152
45
57
17
45
13
37
11
34
9
17
5
342
100
Upper Lower
19 135
7
Upper Lower
20
1
37
2
Upper
18 27
1
Lower Upper Lower
15
1
22
H
Upper Lower
22
2
12
1
Upper Lower
10
H l
Total
7 342
l2
*Frequency of occurrence in a classification proposed at the University of California for cases requiring treatment; based on a group of 620 study models from 130 patients for whom a total of 342 removable partial dentures had been made. (Original tabulation, January 1927, revised M ay 1941.)
lo n g saddle side. In short, the n ature o f the appliance is p a rtly th a t o f a bridge an d p a rtly th at o f a plate denture. T H E TH IRD C L A SS
T h e n um ber o f anterior teeth rem ain in g and their relation to the spaces is sub ject to m u ch variation . O ccasion ally, there are double spaces on one side, and, in rare instances, on b oth sid es; i.e., there m a y b e a tooth standing betw een th e rem ain ing anterior teeth and the pos terior group, an d this condition m a y be bilateral. N u m erically, this class is not
effect a rem ovable bridge, com prised o f saddles, conn ectin g bars and clasps. H a v in g the characteristics o f a p a rtial plate denture, it freq u en tly is referred to b y the n am e p artial plate. T h e choice w ill be m ade m ain ly accord in g to the len gth o f the spaces, bridges fo r th e short ones, p artial dentures fo r the lon g ones, the latter p articu la rly i f the crowns o f the abutm ents are not carious. T y p e o f A p plian ce In d ica ted.— U n d e r the conditions just cited, the restoration usu ally w ill take the form o f n arro w saddles connected b y bars fo r transverse
M a u k — M u t il a t e d D e n t a l A r c h e s
b ra cin g and w ith the necessary clasps for retention and also designed w ith suitable rests to receive support a t a ll possible points on rem ain ing teeth. T h e saddles serve p rin cipally to c arry the necessary artificial teeth and to prevent fo o d p ack ing, b u t do not m a terially add to sup port in m astication. F unction R estorable.— T h is class, to gether w ith the sixth, presents better possibilities o f restoring fu n ction than any o f the others, since the appliance can be com pletely tooth borne. th e fo urth cla ss
In the extrem e cases o f the fourth class in the upp er ja w , the space som e times extends to one-half, o r m ore, o f
A
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ch an geab ly w ith the opposite side, w ith ou t a n y conscious difference. In the sec ond instance, because it is possible to restore on ly a fraction o f the origin al fu n ction , the patien t is m ost likely to chew on the sound side opposite the restoration alm ost en tirely fo r both effi cien cy and com fort. T h e restoration then fulfils a secondary though very im p ortan t phase o f fu n ction ; nam ely, m ain tenance o f the vertical location o f the opposing teeth, w h ich m eans m a in tenance o f th e vertical dim ensions o f the low er third o f the face. Since the attem pt is here b eing m ade to classify cases requiring a partial d en ture o f the saddle-bar-clasp type, rath er than fixed o r rem ovable bridges, it is logical to sp ecify “ a lon g space” as the id en tify in g fea tu re o f this class. T y p e o f R estoration.— T h e type o f restoration ind icated usu ally calls fo r a
B
C D Fig. 13 .— Combinations of: A , cl. B, cl. 2 and 5 ; C , cl. 3 and 5 ; D , cl. T he problem of the restoration and tional importance for the posterior of major importance in such cases.
A B Fig. 14 .— Combinations of: A , cl. 5 and 2 ; B, cl. 5 and 3 . In these cases, functional and restoration problems for the anterior space are usually predominant. 1 and 5 ; 4 and 5 .
its func spaces is
the arch. In this class as in the third, the sam e difficulty is again a p p a r e n t: to es tablish a definite physical lim itation, w h ich w ill in d icate w heth er bridgew ork or a p a rtial plate denture shall be used. A short space w ith a tooth posterior to it w o u ld fa cilita te the use o f a b rid ge w ith both ends w ell supported, w hereas the occurrence of a lon g space w ith no posterior teeth elim inates th at possibility. In the first instance, fu n ctio n a l restora tion m a y b e so n ea rly com plete th a t the p atien t uses this area o f the arch inter-
b ar fo r transverse b racin g effect, a sad dle designed fo r m axim u m bearin g effect and th e clasps necessary fo r reten tion. F u n ctio n R estorable.— A s . a lread y cited, the fu n ctio n restorable can b e o n ly fraction al, even w ith a posterior su p port in g tooth present. THE FIFTH CLASS
T h is class o f case m a y v a r y from the space o f a single m issing anterior tooth to an extrem e condition w here only the m olars rem ain, as in F igu re 1, A . T h e condition is th e ex a ct opposite o f th a t in Class 1. W ith a short space present, the m eans o f treatm ent, accord in g to the best
2 1 30
T h e J o u r n a l o f t h e A m e r ic a n D e n t a l A s s o c ia t io n
prevailin g practice, w ou ld u su ally be a fixed bridge, although, w ith a fixed bridge, it is o ften m ore difficult to secure an esthetic effect th an w ith a partial rem ovable denture. W ith the extrem ely lo n g space, as in F igu re i , A , it is dou bt fu l w hether a n y type o f p a rtial denture w o u ld be o f p ractical va lu e and it could be considered o n ly tem porary a t best. T h e interm ediate fcondition, w herein fou r, five or perhaps six teeth are miss ing, is the usual one. T h is class o f m u ti lation is freq u en tly the result o f traffic an d sports accidents, and cases are on record w herein all eigh t incisors w ere lost in this w ay. T y p e o f R estoration In d ica ted .— T h e restoration ind icated is u su ally a saddle w ith tw o distal bars fo r a longitudinal b ra cin g effect, togeth er w ith anterior clasps or sim ilar retain in g devices d e signed w ith rests to receive support from the teeth ad ja cen t to th e space an d w ith the posterior clasps o r their eq u ivalen t so p laced as to exert strong resistance against th e tiltin g effect in the anterior area fro m the pressure o f occlusion. F u n ctio n Restorable.— T h e condition present is not ve ry fa vo ra b le fo r restora tion o f the m ain fun ction o f the anterior teeth, incision o f foo d masses. T h e a p p lian ce cannot b e v e ry effectively used fo r b itin g off masses o f h a rd or tou gh foods because o f the p a in fu l effect on the u n derlyin g tissues and the proxim atin g tooth abutm ents i f m u ch fo rce is used. Also, the repeated excessive m ove m ents o f the abutm ent teeth w ould result in their prem ature loosening and e a rly loss. T h e secon dary functions of the anterior teeth, the p a rt th a t th ey p lay in speech and as an aid to the ap p ear ance, can be and u su ally are alm ost com p le tely restored b y a rem ovable partial denture appliance.
m ain in g teeth are ve ry likely to be single or in twos. T h e re are so m an y variations th at the cases present no distinct ch ara c teristic excep t irregularity. I t m a y be considered a m iscellaneous class because o f the fa c t th a t it is com prised o f a sm all n um ber o f cases th at do not fit rea d ily into the oth er classes. T y p e o f Restoration In d ica ted .— W h en this kind o f case is not treated b y m eans o f a series o f sm all fixed bridges, as is often done, or a rem ovable bridge w ith precision attachm ents, tw o oth er m eans o f treatm en t are resorted to, both com in g in th e category o f p artial plate dentures. O n e, consisting o f saddle an d clasp units jo in e d b y bars, is ap p licab le to both u p p e r and low er cases. T h e other, fo r u p p er cases only, consists o f a broad base coverin g m ost of the vau lt, w h ich in some instances is retained b y clasps and in oth er cases is used w ith ou t clasps. F u n ctio n Restorable.— In this class, w hen the rem aining teeth h a ve good perid en tal attachm ents, and th eir fu ll support is utilized fo r the denture, fu n c tion can b e alm ost com pletely restored, for a lon g term o f service to the patien t. I f the perid en tal attachm ents are d e stroyed, fu n ctio n can be restored o n ly in p a rt and the treatm ent b y an appliance can not b e considered other than a tem p o rary expedient. C om b in ation class 1 + 5 . (F ig. 13, A .)
43 |12345
C om b in ation class 2 + 5 . (F ig. 13, B .) 4 3211
34
78
C om b in ation class 3 + 5 . (F ig. 13, C .) 87
43
112 3
78
T H E SIX T H C L A S S (IR R E G U L A R SPA C E S ARO UN D T H E A R C H )
T h is is a sm all grouip o f cases w herein a n um ber o f short spaces are fou n d w ith no regu lar arran gem en t in th e arch. R e
C om b in ation class 4 + 5 . (F ig. 13, D .) 4321| 345678
M a u k — M u t il a t e d D e n t a l A r c h e s
COM BIN ATIO N OR BLEN DIN G O F C LASSE S
In a sm all percen tage o f cases, the ou t standing features o f w h ich grou p them in class 1, 2, 3 o r 4, there m a y be an ad ditio n al space in the anterior region (class 5 ). S uch a space w ou ld require ad ditional details in the design o f the restoration fo r the case, b u t the essential ch aracter o f the case is nevertheless that o f the m ain group. T h e restoration problem is prim arily th a t of class 1, 2, 3 o r 4 plus a secondary com bination ele m ent o f class 5. E xam ples are shown in F igu re 13. C om b in ation class 5 + class 2. 8 76 43
I
3 4 56
(F ig. 14, A .) C om bin ation class 5 + class 3. 87 54
|
34
7
(F ig. 14, B .) I n the same w ay, a class 5 case m ay h a ve an additional posterior space or spaces on one or b oth sides of the arch as described fo r class 1, 2, 3 and 4. T w o exam ples are illustrated. (F ig. 14, A and 14, B .) « Instead o f setting up a separate class or subclass o f each o f these and thus com plicatin g the w hole classification schem e to such a n extent that it w ould tend to becom e u n w ieldy, it is m ore con sistent w ith the purpose o f the plan to consider these as blends or com binations o f tw o classes and to develop restoration in accordan ce w ith the class the features o f w h ich are predom inant. Since the tim e w h en this tabu lation was origin ally m ade, in 1927, it has been largely confirm ed b y extended clinical experience, reen forced b y a fu rth er a c cum ulation o f m odels. I t is w orth y o f interest to note that even the cases th a t are referred to as in freq u en t and those term ed deferred fu ll denture cases also com e w ith in the limits o f the classification, althou gh some m igh t b e considered extrem e exam ples. I h ave given consideration to the idea
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that this classification, w ith some a d d i tional featu res defining and lim iting the len gth o f spaces, m ight be ad vantageou sly used fo r b rid ge cases as w ell as fo r r e m ovab le p a rtial denture cases. F rom the standpoint o f statistics, it m a y ju stly be said th at in order to estab lish a m ore conclusive n um erical se q uence, a m u ch larger num ber o f cases should h a ve b een used. Selectin g cases feasible fo r treatm ent b y m eans o f re m ovab le p a rtial dentures from a lim ited n um ber o f m odels leaves small totals in some o f the groups. Instead o f abou t 1,000 m odels w h ich w ere sorted to obtain the fo reg o in g results, there should p re fe ra b ly b e perhaps abou t 5,000 gathered from all kinds o f dental practice, sub urban and m etropolitan. T h e ph ysical difficulties of securing such a large n um ber o f m odels can be read ily understood, especially b y those w ho h a v e attem p ted a n y form o f statis tical effo rt in the dental profession. It w ou ld require a w ell-financed u n d er taking, to b e closely follow ed u p b y com petent clerical assistance. H o w ever, the tendency to norm al dis tribution should hold good so th at the tabu lation as it stands can safely b e taken fo r p ractical purposes as a cross-section o f the field o f dentistry w here treatm ent b y m eans o f rem ovable partial dentures is indicated. BIB LIO G R A PH Y
1 . M c C o l l u m , B. B.:
Factors T hat Make M outh and T eeth a V ital Organ. J.A .D .A ., 1 4 : i 2 6 i, July 19 2 7 . 2 . Idem : M edical and Dental Relations. J.A .D .A ., 2 2 : 1848 - 1849 , November 1935 . 3 . Idem : Is It Necessary to Replace Missing T eeth? J.A .D .A ., 2 4 :445 , M arch 19 3 7 . 4 . C u m m e r , W . E .; T u r n e r , C . R., and A n t h o n y , L. P.: American System of Pros thetic Dentistry. Ed. 6 . Philadelphia: Lea & Febiger, 1932 , pp. 343 - 344 . 5 . P r o t h e r o , J. H .: Prosthetic Dentistry. Ed. 2 . Chicago: M edico Dental Publishing Co., 19 16 , p. 7 3 . 6 . K e n n e d y , E d w a r d : Partial Denture Con struction. New York: Dental Items of Interest Publishing Co., 1928 , pp. 3 -8 . 176 Highland Blvd.
AMERICAN DENTAL ASSOCIATION V o l. 29
D E C E M B E R 1, 1942
N o. 19
A CLASSIFICATION OF MUTILATED DENTAL ARCHES REQUIRING TREATMENT BY REMOVABLE PARTIAL DENTURES B y E d w in H . M
auk
, D .D .S ., Berkeley, C alif.
N Y consideration o f rep arative den tistry m ust start w ith the ideal or standard o f tw o u nbroken dental arches o f sixteen teeth e a c h ; the low er a ctivated b y the muscles o f m astication attach ed to the m andible, the tw o to gether aided b y the cheeks, th e tongue and the lips perfo rm in g the fu n ction o f tritu ratin g food and m ixin g it w ith saliva to prep are it fo r d e g lu titio n ; i.e., m asti cation. W h ile m astication o f foo d is no doubt the m ost im portant fu n ctio n o f the teeth and jaw s, it m ust be noted th at th ey fu l fil other essential physiologic purposes as w ell. T h e y aid in deglu tition an d they h ave an im portant part in th e production o f s p e e c h ; and it is w ell understood that good appearance is largely dependent on the presence o f a fu ll set o f teeth in such alin em en t as to m ain tain correct and pleasing relations o f the low er third o f the fa ce to the head as a w hole.
A
Read before the Section on Partial Denture Prosthesis at the Eighty-Third Annual M eet ing of the American Dental Association, Hous ton, Texas, October 27 , 19 4 1 . Jour. A .D .A ., Vol. 29, December 1, 1942
F o r the m ain tenance o f these fu n c tions at their highest efficiency, each m em ber o f the arch m ust ( 1 ) h ave u n broken contours and (2) be in lateral con tact w ith its contiguous mem bers. I t w ill b e noted th a t this fa c t conform s to the physical law s govern in g the use o f the arch in various phases o f architecture. Som e authorities term the com pleted dentition w ith its surrounding oral parts an organ, just as w e refer to oth er organs in the body, because o f the ve ry im por tan t role the den tal equipm ent has to p la y in the ph ysiologic processes of the entire system .1’ 2 W h en ever the arch b e comes m u tilated b y losing some o f its m em bers, i.e. w hen teeth are extracted, the m asticatin g fu n ction is im paired in proportion to the num ber o f lost m em bers as w ell as the position th at th ey o c cupied in the arch. T h e initial b reak in arch con tin u ity is follow ed b y a w hole train o f d en tal evils. It is com m on know ledge th a t the teeth on each side o f the break, w hen deprived o f th eir lateral contact, strongly tend to rotate, to tip into the space and to b e 2121
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T h e J o u r n a l o f t h e A m e r ic a n D e n t a l A s s o c ia t io n
com e loosened. D estru ction o f the p eri d en tal m em brane follow s, w ith serious derangem ent o f the occlusion. U nless a rem ed y is applied b y m eans o f repair or b y reconstruction, th e condition m ay rap id ly progress to com plete disintegra tion o f the entire d ental arch , finally necessitating the rem oval o f a ll the teeth com posing it. I t is true th at third m olars can be rem oved from the ad u lt d en tal arch and the continuity o f the rem ain ing mem bers b e un affected an d fu n ction unim paired, an d also th at the loss o f a single tooth from the arch of a y o u n g person m ay often be com pensated fo r by the m oving o f other teeth to close the gap , although
Fig. I.— Types omitted from classification. Anchorage for retention being insufficient, par tial dentures tend to convert the conditions rapidly into full denture cases.
this is questioned b y som e authorities. A lm ost all other cases o f m u tilation of the a rch call for a m ore constructive rem edy in the form o f a so-called p a rtial denture, either fixed or rem ovable. T h e A m erican D en ta l Association, it is approp riate to note here, has m ade a ru lin g in recent years th a t a section of th e organization know n as th e Section on P artial D en tu re Prosthesis shall devote itself to the discussion o f a ll form s o f d en tal restorations o f m ore than one tooth and less than th e entire arch w h eth er th ey be fixed or rem ovable. D e n
tal teachers and w riters on this su b ject h a ve agreed th a t it is alm ost im possible to establish a distinct line o f dem arcation in d efin ing a partial denture a n d a re m ovable bridge. In general, an a p p li ance h a v in g saddles together w ith con n ectin g bars and clasps is referred to as a p a rtial denture or, m ore prop erly, a rem ovable p a rtial denture. S im ilar restorations h a vin g precision attachm ents fittin g into crowns o r inlays in th e abu t m ent teeth are p o p u larly term ed rem ov able bridges. T h is discussion w ill deal exclu sively w ith the p artial rem ovable d enture or partial plate d en tu re type. T h e fixed and rem ovable bridge types,
Fig. 2 .— Types omitted from classification because infrequent. The usual means of treat ment is more in the nature of a cantilever bridge than a partial denture of the type under discussion.
together w ith designs for the restorations them selves, w ill be om itted ex cep t for co llateral reference. In fo llo w in g accepted m odern p ractice in m ed ical and d ental science, w h ich de m ands a detailed diagnosis based on all the availab le facts w h ich can serve as a gu id e in form u latin g the specifications o f th e rem ed y to be applied, it becom es necessary to h ave a classification o f cases th a t w ill id en tify the outstanding types w ith o u t recourse to a cum bersom e toothb y-tooth and space-by-space description, and, i f possible, to include some o f their
M
auk
— M
u t il a t e d
features. (“ A p lan of treatm ent should fo llo w and b e dictated b y a diagnosis, and can b y no stretch o f the im agina tion take the place o f it.” 3) F o r the purpose o f classification, w e need not consider the pathologic condi tions th a t cause a break in the arch b y the loss o f teeth, because all pathosis has presum ably b een elim inated b y the e x traction w h ich creates the space.
Fig. 3 .— T ype with short spaces not class ified separately, although included in main groups. T he restorative means takes the form of a bridge.
D
ental
A
rches
2123
position o f the rem aining teeth. A ctu a lly , these are the conditions th a t lim it the usefulness o f a n y appliance fabricated fo r rem ed ying the deficiency. I t m a y be regarded as axio m atic th at the m asticat in g fu n ction w h ich can be considered restorable is in direct proportion to the num ber o f rem ain ing teeth. Im m ediately a classification is a t tem pted a lo n g this line, i.e. the spaces existin g in the arch, tw o form idable diffi culties arise. O n e is the m athem atical m agn itu d e o f possible com binations. B e gin n in g w ith the loss o f one tooth, and progressing to the com plete destruction o f one arch o f sixteen members, this runs into m an y thousands as com puted by C u m m er, w ho says th at “ in either the
Fig. 4 .— Cases, with relatively long spaces compared to those of Figure 3 , classified as requiring partial dentures, which afford sup port and lateral bracing effect not obtainable by means of bridges. Fig. 6 .— Partial denture as advertised, an example of mechanical design disregarding functional needs. It lacks effective support.
Fig. 5 .— T ype included in classification be cause either partial denture or bridges may be means of treatment. (Compare description of Class 6 .)
O b viou sly, then, in m utilated arches, the m ain factors to be classified are the ph ysical conditions. T hese consist o f (1) the num ber, len gth and position of the spaces, w h ich offer the m ost apparent evidence o f im paired fu n ction o f the den tal organs, and (2) the n um ber and
u p p er or low er jaw , there can be 65,536 cases.” 4 E xcep t fo r statistical purposes, such a classification w ould be virtu a lly useless. Its m an ifold com plexities w ou ld p rohib it a n y fu rth er consideration o f its application in den tal p ractice as a basis fo r grou p in g sim ilar cases that occur fre quently. T h e other difficulty, th at o f m akin g a classification sufficiently lim ited to com e w ith in the range o f usefulness, in evitab ly results in a com prom ise b y om ittin g some com binations th at are o c casionally observed. T h e re is a w ell-established precedent fo r such a com prom ise, n otably the B lack
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T h e J o u r n a l o f t h e A m e r ic a n D e n t a l A s s o c ia t io n
classification o f tooth cavities, w h ich does n ot include all cavities occu rrin g on all tooth surfaces. It is h ig h ly significant that, in spite o f these omissions, the B lack c a v ity classification has com e into alm ost universal use in the field o f opera tive dentistry and has stood the test o f usage over a lon g period of tim e. M o re over, some o f the possible com binations o f spaces and teeth rem ain ing in the arch a re such th a t a p artial denture w ould b e inefficient o r w ou ld tend to cause early rem oval o f thé teeth th at are in position. T h ese cases should b e regarded as tem p o rarily deferred fu ll denture cases,
classification, as in the instance o f the B lack c a v ity classification. (Fig. 2.) A th ird grou p presents short spaces for w h ich bridgew ork, eith er fixed or o f the rem ovable type, is unm istakably th e best rem edy. T h erefo re , it is n ot necessary to in clu d e this grou p as a separate class in a classification o f cases w h erein re m ovable p artial dentures are indicated.
F ig . 7.— L a r g e s t c la ssific a tio n g r o u p , id e n ti fie d b y b ila te r a l sp a ce s w it h n o te e th p o s te rio r to th em . A p a r t ia l d e n tu re w ill b e la r g e ly tissu e b o rn e . T h e re sto ra b le fu n c tio n is q u ite lim ite d .
Fig. 9 .— Bilateral spaces with posterior tooth support available on both sides. The restor able function is relatively greater than in other types, except Class 6 , if spaces are of moderate length.
Fig. 8 .— Posterior spaces, bilateral. Posterior tooth support is available on one side. The restorable function is greater than in Class 1 .
Fig. 10 .— Unilateral space, very unfavorable for restoration of masticating function, al though remaining teeth compensate unless interjaw relation is similar to that shown here. Secondary functions, i.e. aid in speech and appearance plus maintenance of vertical jaw relations, are almost w holly restorable.
therefore it is n ot necessary to inclu d e them in a p a rtial denture classification. (F ig. 1.) In th e accom p an yin g series o f draw ings, only typical instances have b een selected fo r illustration am ong all the com binations th a t m ay occu r in the class indicated. W id e latitu d e exists w ith in each class fo r v a riatio n s; th at is to say, the classification is flexible. A second group o f com binations pos sible in eith er arch occu r so infreq u en tly as to be o f quite m inor im portance and can be safely disregarded in a w orking
(Fig- 3 -) H o w ever, this grou p m erges in to those h a vin g m u ch longer spaces. I t is only necessary to regard the spaces in F igu re 3 as b ein g considerably increased b y the fu rth er loss o f teeth, w h ereu p on the con-
ditions th a t lo gically require p a rtial d en tures o f a rem ovable type readily becom e apparen t. (F ig. 4.) T h erefo re all these groups are included in the m ajo r classes shown later. A fo u rth grou p , h avin g m u ltiple short spaces, com prises cases w herein either b rid gew ork o r a rem ovable p artial d en ture can b e used as the rem edy o f choice. T h erefo re, this grou p should b e included
M a u k — M u t il a t e d D e n t a l A r c h e s
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in the classification u n der discussion. (F ig. 5.) T h e choice depends on several facts. F requently, it is determ ined b y the condition o f the abu tm ent teeth. I f their crowns are so b a d ly d ecayed th a t they require restoration, suitably b y bridgework, this w ou ld seem to be a decisive fa c t in fa v o r o f bridgew ork as the most desirable means o f treatm ent, provided the peridental attachm ents are in good condition. O n the other hand, if the abutm ent teeth are not carious, oth er facts m ay prove to be conclusively in fa v o r o f treat m ent w ith a rem ovable partial denture. T h e patien t m a y justifiably ob ject to the cu ttin g o f sound tooth surfaces, either from d read o f the w ea r and tear on the nervous system or from a fea r of losing the teeth due to some previous u n fortu nate experience w ith crowns.
brid gew ork h a vin g been elim inated as outlined above, the rem ain ing cases can n ow be grou p ed u n der a triad com prising all the features w h ich it is essen tial to recogn ize in a classification o f this kind, as fo llo w s : 1. F re q u e n cy o f occurrence, w h ich w ou ld in d icate the num erical order o f each class. 2. Position and extent o f the space or spaces in the arch, w h ich w ou ld in d icate the type o f applian ce to be fabricated to rem ed y the m utilation. 3. T h e exten t o f support availab le in the form o f rem ain ing teeth a t the ends o f spaces, w h ich w ou ld ind icate the am ount o f fun ction, especially m asticat in g fun ction, th a t it is possible to restore b y m eans o f the applian ce used. B y m akin g this approach to the p ro b lem , th a t is, an approach from the bio-
Fig. 1 1 .— Single anterior space. The class ification is unaffected by the absence of third molars. The case is favorable only for restora tion of the secondary phases of function.
Fig. 12 .— Irregular spaces around entire arch, favorable for restoration of function un less peridental attachments are badly impaired.
U n d e r these conditions, the use o f a p artial denture w ou ld avoid the form id able cu ttin g n eeded fo r bridge a tta ch ments. T h e resultant econ om y o f both ch air and laboratory tim e w ou ld perm it a low er fee, w h ich in itself is a n im por tan t fa cto r in m an y cases. F in ally, a n oth er fa c t m ay determ ine the c h o ic e : I f the peridental attach m ents o f the abu tm ent teeth are m u ch im paired, a partial denture w ith its conn ectin g bar w ill h a ve the ad va n ta ge o f a b racin g effect across or aroun d th e arch, actin g as a splint, w h ich w ou ld not be the case w ith b ridgew ork in tw o or m ore separate pieces. T h e cases th at m a y be term ed deferred fu ll denture cases, the cases th a t occur in freq u en tly and the cases requiring
logic o r ph ysiologic standpoint o f im paired fu n ctio n o f an organ, the possi bilities o f the attem p t to com pensate fo r lost fu n ction b y the use o f an appliance, and also its definite lim itations, w ill be better understood. D esigns for the v a ri ous types o f cases w ill then develop w ith this consideration, fu n ctio n al efficiency, as the m ost im portan t essential. I f the a p proach is m ad e from the engineering standpoint prim arily, the resulting ten d en cy in design is to stress m echanical d e tails and thus to prod u ce refined m ech anisms th at m a y fa ll fa r short o f effi cien cy in function. F o r instance, a rem ovable p artial d en ture is som etim es m ade to supply a ll o f the u p p er teeth b ack o f the cuspids, h a v ing v e ry n arro w saddles and w ith a light
2 12 6
T h e J o u r n a l o f t h e A m e r ic a n D e n t a l A s s o c ia t io n
skeleton fram e across the v a u lt and a rou n d the lin gu al aspect o f the anterior teeth. (Fig. 6.) T h is is a n exam ple o f m ech an ical refinem ent d eveloped per haps in response to the usiial dem and of th e patien t fo r lightness, fo r m inim um b u lk, leavin g the v a u lt open, and fo r a general appearan ce sim ilar to th a t o f fine jew elry. S uch a restoration, though it m a y please the patien t at first, lacks th e essential feature fo r go od fu n ctio n ; th a t is, a broad bearin g a rea on soft tis sues, since there are n o posterior teeth fo r support. C on seq u ently, the denture fails to resist m asticatin g stress suffi ciently, settles ra p id ly ou t o f occlusal con tact and loosens the abu tm en t' teeth prem aturely. A base w ith va u lt cover age, either in fu ll or in p art, w ou ld be m u ch better ad ap ted to m eet the de m ands o f m astication in this case. T h e classification given later was evolved b y a p p ly in g the foregoin g prin ciples to a collection am ou n tin g to about 1,000 m odels accu m u lated in th e pros thetic infirm ary over a period o f years w ith this ob ject in view . R ep ea ted p re lim in ary sortings and groupings elim inated ( i ) the in freq u en t cases; (2) the cases in w h ich p artial dentures w ere im practical because too fe w teeth rem ained fo r ad equate reten tio n ; (3) the cases in w h ich rem oval o f a considerable num ber o f teeth, com prising a ll those rem aining in the arch, was im m in en t because of periden tal destruction, and (4) thè cases in w h ich brid gew ork w as obviously the m ost desirable m eans o f treatm en t be cause o f the short spaces existing. T h is le ft about 600 m odels, m ore than one th ird o f the origin al n um ber h a vin g thus been set aside. T h is rem ain ing n u m ber was re arran ged in six groups, w h ich w ill be described. A critical and extend ed study w as m ade o f this arran gem en t to test its a p plicatio n to clin ical p ra ctice and its c a p a c ity to includ e a ll cases in w h ich p a rtial dentures h a d b een successful. T h is stud y finally led to th e conclusion th at this lim ited selection w o u ld repre
sent n ea rly o r qu ite a ll those cases in w h ich p a rtial denture construction w ou ld be feasible as th ey com e into the hands o f the general practitioner. In short, a w orkable classification o f com parative sim plicity fo r d ay-in and d ay-ou t needs ha d b een gra d u ally form u lated in h a r m on y w ith the three features en um er ated. T h is w as lack in g in m ath em atical and statistical com pleteness, as m igh t be exp ected , b u t it em bodied an inh erent fa c ility fo r id en tifyin g and com parin g the con stan tly recu rring cases so th a t the resultant design could be evolved lo g ic a lly acco rd in g to m inor differences am on g cases in the same class. T h is classification w as ten tatively ad opted fo r classroom an d clin ical w ork abou t 1926, continuing to d a te.* I t has proved a valu ab le aid in teach in g and in keep ing records. L a te r adopted b y g ra d uates fo r office practice, it is com in g into m ore gen eral use b y the profession. A ll p ractical and statistical observations seem to in d icate th at it is sufficient fo r general needs. I t is hoped that, like the B la ck c a v ity classification, because o f its sim plicity and its a bility to describe the conditions th at it classifies, it w ill w ith stand th e test o f tim e and extended usage. T h e separate groups com prising the classification are as fo llo w s : C lass 1 : B ilateral posterior spaces, rem ain in g teeth in a segm ent in the anterior area.
43211123
(F ig. 7, A )
321|1234
(F ig. 7, B)
Class 2 : B ilateral posterior spaces, one or m ore teeth a t the posterior o f one space. 87 43211123 (F ig. 8, A ) (F ig. 8, B )
54321(1234 78
C lass 3 : B ilateral posterior spaces, one or m ore teeth a t the posterior o f both spaces. 8 3211123 8 (F ig. 9, A )
87
32111234
8
(F ig. 9, B )
•U niversity of California, School o f Den tistry.
M a u k — M u t il a t e d D e n t a l A r c h e s
Glass 4 : A unilateral posterior space, with or without teeth at the posterior of the space, the arch unbroken at the op posite side. 87654321|123
(Fig. 10, A)
4321112345678
(Fig. 10, B)
Class 5 : Anterior space only, posterior part of the arch unbroken on either side. 7654 | 345678 (Fig. 11 , A) 87654 | 345678 (Fig. 11 , B) Class 6 : Irregular spaces around the arch, remaining teeth single or in small groups. 8 6 4 21| 3 5 7 (Fig. 12, A) 8 65 3 | 3 67 (Fig. 12, B) t h e f ir s t c l a s s
(t a b u l a t io n )
The teeth in the anterior region usu ally number six to ten. They m ay be in equalor unequal arrangement on each side of the median line, with a strong tendency for this arrangement to be sym metrical. Nearly all writers on this subject seem to note this type as occurring more fre quently than any other, and to mention it first in efforts to classify their cases, but do not cite any statistical facts .5 This group, perhaps better than any o f the others classified, permits the appli cation of the triad of features enumer ated, which stand out as demanding recognition in the plan o f classification. T h e First Feature. — Numerical fre quency, about 45 per cent, is strikingly apparent in the tabulation given here with, which logically therefore gives this type first place as a class in accordance with the triad. T h e S econ d Feature. — T he spaces, bilateral and posterior, indicate that the restoration will necessarily have to be one depending very largely on the soft tissues for support in mastication. This cannot be otherwise, since the remaining teeth can furnish only a limited part of the support necessary because of their anterior position out of the main area of mastication.
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T h e T h ird Feature.— T h e am ount o f fu n ction restorable is closely related to the second featu re. O w in g to absence of posterior tooth-bearing, fu n ctio n can be restored to o n ly a lim ited degree. T h e fu n ction o f th e n atural teeth in the pos terior areas is m ain ly m astication. T h e y h ave b u t little to do w ith the fu n c tion o f speech, b u t th ey are the teeth that, m ore th a n a n y other p a rt of th e dentition, h a ve the im portant secondary fu n ction o f m ain tain in g the vertical relations b etw een the jaw s. T h is type o f p artial d en tu re can not ad eq u a tely m eet the dem ands o f m asticatin g efficiency because the tissues w h ich h a ve to support it can b ear o n ly a fractio n al p a rt o f the a vailab le m u scu lar fo rce w ith ou t severe pain and perm anent in ju ry. F o r sim ilar reasons, the attem pts th at are m ad e to restore and m ain tain vertical in terjaw space w ith this kin d o f denture are sub je c t to the sam e cause o f failu re, as it is fou n d th a t th e supporting tissues resorb too ra p id ly u n d er these conditions to preserve the space fo r w h ich the a p p li ance is designed. T h u s, the condition m a y b e sum m ed up b y saying th a t w hile this grou p co m prises alm ost h a lf o f all p artial denture cases, the p a rtial denture used in its trea t m en t is u n fo rtu n a tely the least efficient o f all types in restoring fun ction, alth ou g h ' it m a y be v e ry successful as regards com fort and satisfaction to the patien t w hen the a p p lian ce is p rop erly designed and executed. t h e se c o n d c l a s s
T h e second class occurs m u ch less fre q u en tly th an the first, alth ou gh it does inclu d e a w id e va riatio n in the n um ber o f rem ain ing teeth and their location in th e arch. T h e r e is less tend en cy fo r an equal n u m ber o f teeth to be le ft on each side o f the m ed ian lin e ; in fa ct, it is usual to find a short space on one side and a lon g space on the other. T h e T y p e o f A p p lia n ce In d ica ted .— T h e ap p lian ce indicated is one dep en d in g entirely, o r n ea rly so, on tooth sup
212 8
T h e J o u r n a l o f t h e A m e r ic a n D e n t a l A s s o c ia t io n
p o rt on one side o f the arch, the oth er side d erivin g its support to a great extent fro m the u n derlyin g m ucous tissue espe c ia lly in the u p p er arch. T h e F unctiori R estorable.— T h e possi bilities o f restoring fu n ctio n are m u ch better th an in the first class ow in g to th e fa c t th at m ore positive support is a vailab le a t both ends of one space. I t is fou n d , as m igh t b e expected, th a t this side o f the applian ce is h a b itu ally used b y the patien t fo r ch ew in g efficiently and com fo rta b ly rath er th an the opposite or A
Class 1
2
3 4 5
6
ve ry frequent. In distinction fro m Glass i and C lass 2, the prosthetic treatm ent fo r it is essentially bridgew ork, since there is tooth support availab le a t both ends o f a ll spaces. I t m ust b e evid ent that, in this class o f case, there can b e no clear line o f dem arcation betw een rem ov able brid gew ork and so-called p artial dentures. T h e restoration m a y be eith er fixed b ridgew ork, rem ovable brid gew ork h a v in g precision attachm ents fo r retention and support or a n appliance th a t is in
S u r v e y o f P a r t ia l D e n t u r e C a s e s *
Teeth
Proportion Upper to Lower
Class Total
Approximate Per Cent
1
152
45
57
17
45
13
37
11
34
9
17
5
342
100
Upper Lower
19 135
7
Upper Lower
20
1
37
2
Upper
18 27
1
Lower Upper Lower
15
1
22
H
Upper Lower
22
2
12
1
Upper Lower
10
H l
Total
7 342
l2
*Frequency of occurrence in a classification proposed at the University of California for cases requiring treatment; based on a group of 620 study models from 130 patients for whom a total of 342 removable partial dentures had been made. (Original tabulation, January 1927, revised M ay 1941.)
lo n g saddle side. In short, the n ature o f the appliance is p a rtly th a t o f a bridge an d p a rtly th at o f a plate denture. T H E TH IRD C L A SS
T h e n um ber o f anterior teeth rem ain in g and their relation to the spaces is sub ject to m u ch variation . O ccasion ally, there are double spaces on one side, and, in rare instances, on b oth sid es; i.e., there m a y b e a tooth standing betw een th e rem ain ing anterior teeth and the pos terior group, an d this condition m a y be bilateral. N u m erically, this class is not
effect a rem ovable bridge, com prised o f saddles, conn ectin g bars and clasps. H a v in g the characteristics o f a p a rtial plate denture, it freq u en tly is referred to b y the n am e p artial plate. T h e choice w ill be m ade m ain ly accord in g to the len gth o f the spaces, bridges fo r th e short ones, p artial dentures fo r the lon g ones, the latter p articu la rly i f the crowns o f the abutm ents are not carious. T y p e o f A p plian ce In d ica ted.— U n d e r the conditions just cited, the restoration usu ally w ill take the form o f n arro w saddles connected b y bars fo r transverse
M a u k — M u t il a t e d D e n t a l A r c h e s
b ra cin g and w ith the necessary clasps for retention and also designed w ith suitable rests to receive support a t a ll possible points on rem ain ing teeth. T h e saddles serve p rin cipally to c arry the necessary artificial teeth and to prevent fo o d p ack ing, b u t do not m a terially add to sup port in m astication. F unction R estorable.— T h is class, to gether w ith the sixth, presents better possibilities o f restoring fu n ction than any o f the others, since the appliance can be com pletely tooth borne. th e fo urth cla ss
In the extrem e cases o f the fourth class in the upp er ja w , the space som e times extends to one-half, o r m ore, o f
A
2129
ch an geab ly w ith the opposite side, w ith ou t a n y conscious difference. In the sec ond instance, because it is possible to restore on ly a fraction o f the origin al fu n ction , the patien t is m ost likely to chew on the sound side opposite the restoration alm ost en tirely fo r both effi cien cy and com fort. T h e restoration then fulfils a secondary though very im p ortan t phase o f fu n ction ; nam ely, m ain tenance o f the vertical location o f the opposing teeth, w h ich m eans m a in tenance o f th e vertical dim ensions o f the low er third o f the face. Since the attem pt is here b eing m ade to classify cases requiring a partial d en ture o f the saddle-bar-clasp type, rath er than fixed o r rem ovable bridges, it is logical to sp ecify “ a lon g space” as the id en tify in g fea tu re o f this class. T y p e o f R estoration.— T h e type o f restoration ind icated usu ally calls fo r a
B
C D Fig. 13 .— Combinations of: A , cl. B, cl. 2 and 5 ; C , cl. 3 and 5 ; D , cl. T he problem of the restoration and tional importance for the posterior of major importance in such cases.
A B Fig. 14 .— Combinations of: A , cl. 5 and 2 ; B, cl. 5 and 3 . In these cases, functional and restoration problems for the anterior space are usually predominant. 1 and 5 ; 4 and 5 .
its func spaces is
the arch. In this class as in the third, the sam e difficulty is again a p p a r e n t: to es tablish a definite physical lim itation, w h ich w ill in d icate w heth er bridgew ork or a p a rtial plate denture shall be used. A short space w ith a tooth posterior to it w o u ld fa cilita te the use o f a b rid ge w ith both ends w ell supported, w hereas the occurrence of a lon g space w ith no posterior teeth elim inates th at possibility. In the first instance, fu n ctio n a l restora tion m a y b e so n ea rly com plete th a t the p atien t uses this area o f the arch inter-
b ar fo r transverse b racin g effect, a sad dle designed fo r m axim u m bearin g effect and th e clasps necessary fo r reten tion. F u n ctio n R estorable.— A s . a lread y cited, the fu n ctio n restorable can b e o n ly fraction al, even w ith a posterior su p port in g tooth present. THE FIFTH CLASS
T h is class o f case m a y v a r y from the space o f a single m issing anterior tooth to an extrem e condition w here only the m olars rem ain, as in F igu re 1, A . T h e condition is th e ex a ct opposite o f th a t in Class 1. W ith a short space present, the m eans o f treatm ent, accord in g to the best
2 1 30
T h e J o u r n a l o f t h e A m e r ic a n D e n t a l A s s o c ia t io n
prevailin g practice, w ou ld u su ally be a fixed bridge, although, w ith a fixed bridge, it is o ften m ore difficult to secure an esthetic effect th an w ith a partial rem ovable denture. W ith the extrem ely lo n g space, as in F igu re i , A , it is dou bt fu l w hether a n y type o f p a rtial denture w o u ld be o f p ractical va lu e and it could be considered o n ly tem porary a t best. T h e interm ediate fcondition, w herein fou r, five or perhaps six teeth are miss ing, is the usual one. T h is class o f m u ti lation is freq u en tly the result o f traffic an d sports accidents, and cases are on record w herein all eigh t incisors w ere lost in this w ay. T y p e o f R estoration In d ica ted .— T h e restoration ind icated is u su ally a saddle w ith tw o distal bars fo r a longitudinal b ra cin g effect, togeth er w ith anterior clasps or sim ilar retain in g devices d e signed w ith rests to receive support from the teeth ad ja cen t to th e space an d w ith the posterior clasps o r their eq u ivalen t so p laced as to exert strong resistance against th e tiltin g effect in the anterior area fro m the pressure o f occlusion. F u n ctio n Restorable.— T h e condition present is not ve ry fa vo ra b le fo r restora tion o f the m ain fun ction o f the anterior teeth, incision o f foo d masses. T h e a p p lian ce cannot b e v e ry effectively used fo r b itin g off masses o f h a rd or tou gh foods because o f the p a in fu l effect on the u n derlyin g tissues and the proxim atin g tooth abutm ents i f m u ch fo rce is used. Also, the repeated excessive m ove m ents o f the abutm ent teeth w ould result in their prem ature loosening and e a rly loss. T h e secon dary functions of the anterior teeth, the p a rt th a t th ey p lay in speech and as an aid to the ap p ear ance, can be and u su ally are alm ost com p le tely restored b y a rem ovable partial denture appliance.
m ain in g teeth are ve ry likely to be single or in twos. T h e re are so m an y variations th at the cases present no distinct ch ara c teristic excep t irregularity. I t m a y be considered a m iscellaneous class because o f the fa c t th a t it is com prised o f a sm all n um ber o f cases th at do not fit rea d ily into the oth er classes. T y p e o f Restoration In d ica ted .— W h en this kind o f case is not treated b y m eans o f a series o f sm all fixed bridges, as is often done, or a rem ovable bridge w ith precision attachm ents, tw o oth er m eans o f treatm en t are resorted to, both com in g in th e category o f p artial plate dentures. O n e, consisting o f saddle an d clasp units jo in e d b y bars, is ap p licab le to both u p p e r and low er cases. T h e other, fo r u p p er cases only, consists o f a broad base coverin g m ost of the vau lt, w h ich in some instances is retained b y clasps and in oth er cases is used w ith ou t clasps. F u n ctio n Restorable.— In this class, w hen the rem aining teeth h a ve good perid en tal attachm ents, and th eir fu ll support is utilized fo r the denture, fu n c tion can b e alm ost com pletely restored, for a lon g term o f service to the patien t. I f the perid en tal attachm ents are d e stroyed, fu n ctio n can be restored o n ly in p a rt and the treatm ent b y an appliance can not b e considered other than a tem p o rary expedient. C om b in ation class 1 + 5 . (F ig. 13, A .)
43 |12345
C om b in ation class 2 + 5 . (F ig. 13, B .) 4 3211
34
78
C om b in ation class 3 + 5 . (F ig. 13, C .) 87
43
112 3
78
T H E SIX T H C L A S S (IR R E G U L A R SPA C E S ARO UN D T H E A R C H )
T h is is a sm all grouip o f cases w herein a n um ber o f short spaces are fou n d w ith no regu lar arran gem en t in th e arch. R e
C om b in ation class 4 + 5 . (F ig. 13, D .) 4321| 345678
M a u k — M u t il a t e d D e n t a l A r c h e s
COM BIN ATIO N OR BLEN DIN G O F C LASSE S
In a sm all percen tage o f cases, the ou t standing features o f w h ich grou p them in class 1, 2, 3 o r 4, there m a y be an ad ditio n al space in the anterior region (class 5 ). S uch a space w ou ld require ad ditional details in the design o f the restoration fo r the case, b u t the essential ch aracter o f the case is nevertheless that o f the m ain group. T h e restoration problem is prim arily th a t of class 1, 2, 3 o r 4 plus a secondary com bination ele m ent o f class 5. E xam ples are shown in F igu re 13. C om b in ation class 5 + class 2. 8 76 43
I
3 4 56
(F ig. 14, A .) C om bin ation class 5 + class 3. 87 54
|
34
7
(F ig. 14, B .) I n the same w ay, a class 5 case m ay h a ve an additional posterior space or spaces on one or b oth sides of the arch as described fo r class 1, 2, 3 and 4. T w o exam ples are illustrated. (F ig. 14, A and 14, B .) « Instead o f setting up a separate class or subclass o f each o f these and thus com plicatin g the w hole classification schem e to such a n extent that it w ould tend to becom e u n w ieldy, it is m ore con sistent w ith the purpose o f the plan to consider these as blends or com binations o f tw o classes and to develop restoration in accordan ce w ith the class the features o f w h ich are predom inant. Since the tim e w h en this tabu lation was origin ally m ade, in 1927, it has been largely confirm ed b y extended clinical experience, reen forced b y a fu rth er a c cum ulation o f m odels. I t is w orth y o f interest to note that even the cases th a t are referred to as in freq u en t and those term ed deferred fu ll denture cases also com e w ith in the limits o f the classification, althou gh some m igh t b e considered extrem e exam ples. I h ave given consideration to the idea
2131
that this classification, w ith some a d d i tional featu res defining and lim iting the len gth o f spaces, m ight be ad vantageou sly used fo r b rid ge cases as w ell as fo r r e m ovab le p a rtial denture cases. F rom the standpoint o f statistics, it m a y ju stly be said th at in order to estab lish a m ore conclusive n um erical se q uence, a m u ch larger num ber o f cases should h a ve b een used. Selectin g cases feasible fo r treatm ent b y m eans o f re m ovab le p a rtial dentures from a lim ited n um ber o f m odels leaves small totals in some o f the groups. Instead o f abou t 1,000 m odels w h ich w ere sorted to obtain the fo reg o in g results, there should p re fe ra b ly b e perhaps abou t 5,000 gathered from all kinds o f dental practice, sub urban and m etropolitan. T h e ph ysical difficulties of securing such a large n um ber o f m odels can be read ily understood, especially b y those w ho h a v e attem p ted a n y form o f statis tical effo rt in the dental profession. It w ou ld require a w ell-financed u n d er taking, to b e closely follow ed u p b y com petent clerical assistance. H o w ever, the tendency to norm al dis tribution should hold good so th at the tabu lation as it stands can safely b e taken fo r p ractical purposes as a cross-section o f the field o f dentistry w here treatm ent b y m eans o f rem ovable partial dentures is indicated. BIB LIO G R A PH Y
1 . M c C o l l u m , B. B.:
Factors T hat Make M outh and T eeth a V ital Organ. J.A .D .A ., 1 4 : i 2 6 i, July 19 2 7 . 2 . Idem : M edical and Dental Relations. J.A .D .A ., 2 2 : 1848 - 1849 , November 1935 . 3 . Idem : Is It Necessary to Replace Missing T eeth? J.A .D .A ., 2 4 :445 , M arch 19 3 7 . 4 . C u m m e r , W . E .; T u r n e r , C . R., and A n t h o n y , L. P.: American System of Pros thetic Dentistry. Ed. 6 . Philadelphia: Lea & Febiger, 1932 , pp. 343 - 344 . 5 . P r o t h e r o , J. H .: Prosthetic Dentistry. Ed. 2 . Chicago: M edico Dental Publishing Co., 19 16 , p. 7 3 . 6 . K e n n e d y , E d w a r d : Partial Denture Con struction. New York: Dental Items of Interest Publishing Co., 1928 , pp. 3 -8 . 176 Highland Blvd.