Pont’s Index and Dental Arch Form

Pont s index and dental arch form

F r a n k W . W o r m s , DDS, M SD T . M i c h a e l S p e i d e l , DDS, M SD R o b e r t J . I s a a c s o n , DD S, PhD L a w r e n c e H . M e s k i n , DDS, PhD, M inn eapo lis

P o n t’s ind ex is an average m easurem ent fo r a g ro up , and alth ou g h it can be applied to all group m em bers, it m ust not be applied to th e individual. P articipants in the study (Navajo m ales and fe ­ m ales, and d en tal students) had ideal occlusions w ith cro w d in g or spacing of less than 1 mm. T h e m easurem ents of th e interarch w id th s of th e m ax­ illary prem olars and first m olars w ere com pared w ith those calcu lated w ith use of P o n t’s index. D ifferen ces

betw een

th e

m easurem ents

ranged

B iological v a riab le s, in an ad e q u a te sam ple size, a re usu ally d istrib u ted along a n orm al distrib u ­ tio n cu rv e. T h e m ean fo r any v ariab les can be calc u lated . I t is tem p tin g to tre a t th e m ean v alue as th e id eal o r norm . T h is is ac ce p tab le as long a s th e n o rm is n o t eq u a te d w ith th e tre a tm e n t goal fo r a given p erso n . A lth o u g h m ean values a re u se ­ ful to d esc rib e po p u latio n s o r tre a tm e n t goals fo r p o p u la tio n s, m eans a re n o t applicable to in­ d iv idual tre a tm e n t plans. A llow ance fo r norm al d isp ersio n o r v ariatio n a b o u t th e m ean m u st b e co n sid e re d . I t is p e rh a p s an h istorical a c cid e n t th a t som e d e n tists in th e ir o rth o d o n tic tre a tm e n t planning h a v e com e to rely o n P o n t’s in d ex , n o t a s an av era g e valu e fo r a rc h form , b u t ra th e r as a n o rm o r sta n d a rd to w hich all dental a rc h es m u st b e fitted . T h is p a p e r d raw s a tte n tio n to th e pro b ab le c o n se q u e n c e s o f neglecting th e c o n c e p t o f n o r­ m al v ariatio n aro u n d a m ean and offers d a ta to su p p o rt th e co n ten tio n th a t u se o f P o n t’s index as a clinical to o l fo r individual tre a tm e n t plan ­ ning is unjustified.

fro m - 1 2 . 5 to + 9 .8 mm fo r p rem o la r w idths, and fro m - 1 5 .1 to + 1 4 .7 mm fo r th e m olar w idths. In most

p articip an ts, th e

observed

m easurem ents

B a c k g ro u n d

of

P o n t ’s

in d e x

w ere less th an th e calculated ones. D ifferences w ere fo un d betw een arch form s in m ales and fe­ m ales w ith sim ilar Pont indexes.

876 ■ JADA, Vol. 85, October 1972

In 1887, D a v e n p o rt1 first d escrib ed norm al o c­ clu sion. I t w as his co n ten tio n th a t all te e th m u st b e p re se rv e d . L a te r, A n g le’s 2 classification sy s­ te m w as pub lish ed an d to g eth er, th e tw o p ap e rs p ro v id e d th e p ra c titio n e r w ith specific tre a t­ m e n t goals. D u rin g this e ra th e c o n cep t o f ex ­ tra c tio n and ap pliance th e rap y h a d n o t y e t been a c c e p ted . C o n se q u e n tly , cro w d ed d e n tal arc h es h a d to b e ex p an d ed until th e full co m plem ent o f

te e th co u ld b e aligned. I t w as th is e x p an sio n th a t led m en to d e v ise fo rm u las an d in d ex es th a t w ould p re d ic t th e p ro p e r am o u n t o f e x p an sio n . B o n w ill,3 in 1887, ad v a n c e d g eo m etric m e th ­ o d s fo r p o sitio n in g d e n tu re te e th . S u b se q u e n t­ ly, th e c o n c e p t o f n o rm al occlu sio n an d th e n e ­ cessity o f a rc h e x p an sio n led H a w le y 4 to a d a p t B onw ill’s g eo m etric m eth o d s to a rc h p re d e te r­ m ination in individuals w ith m alo cclu sio n . B e­ ca u se o f th e co m p lex ities o f th e B onw ill-H aw ley m etho d o lo g y , P o n t,5 in 1909, suggested his m eth ­ od o f arch -fo rm p re d e te rm in atio n , th e P o n t in ­ dex. P o n t m e a su re d th e m esio d istal w id th s o f th e u p p e r c e n tra l an d lateral in ciso rs, th e m axillary in te rp re m o la r w id th s, an d m axillary in te rm o la r w idth s o f an u n re p o rte d n u m b er o f F re n c h p e r­ sons. H e d iv id ed th e av erag e com b in ed w id th s o f th e c e n tra l an d lateral in ciso rs b y th e a v erag e in terp re m o la r w id th an d o b tain ed th e in d ex num ber: xX lx lO O /x P w id th = 8 0 = index n u m ­ b er. T h e m o lar in d ex n u m b e r w as o b tain ed by division o f th e a v erag e com bined w id th s o f th e c en tra l an d la te ra l in ciso rs b y th e a v erag e in te r­ m o lar w idth: x S lx lO O /x M w id th = 6 4 = index n um b er. T h e fo rm u la th e n w as a d a p te d to a rc h ­ w idth p re d ic tio n b y tran sp o sitio n : th e p re m o la r w idth ( P ) = X lx 100/80, an d th e m o lar w idth (M ) = 2 1 x 100/64. T h u s , th e p ra c titio n e r n e e d only m easu re th e sum (2) o f th e w idths o f th e in ciso rs (I) an d c o m p u te th e re sp e c tiv e a rc h w idths. T h e arch fo rm th e n w o u ld b e ex p an d ed to th is co m ­ p u ted w idth, at w h ich p o in t th e en tire d en titio n , it w as su g g ested , could be aligned p erfectly . I t sh o u ld b e n o ted th a t P o n t sam pled an u n d e ­ fined p o p u latio n o f F re n c h p eo p le in th e early p a rt o f th e tw e n tie th c e n tu ry . F ro m th is sam ple he o b tain ed a se t o f e stim ated p o p u latio n m ean s, from w h ich h e d eriv ed th e index n u m b ers. B e c a u se o f th e prevailing n o tio n o f th e ideal arch fo rm , P o n t a p p a re n tly w as co n fid en t in ab ­ stractin g from m e a su rem en ts o f ideal o cclu sio n s th e ideal (F re n c h ) arc h form . P o n t in d icated th e p o ssib le eth n ic b ias o f his sam ple an d urged o th e r in v estig ato rs to valid ate his in d ex es on “ o th e r r a c e s .” P o n t m ad e no allo w an ce fo r v ari­ an ce, alth o u g h his m eth o d w as b a se d o n sam ­ pling te c h n iq u e s and h e h ad ack n o w led g ed th e ex isten ce o f th o se d ev iatio n s in deriving th e m eans. O n c e th e in d ex n u m b ers w ere d e te r­ m ined, th e p re se n c e o f variatio n a b o u t th e m ean w as a p p a re n tly fo rg o tten . J o o n d e p h an d co -w o rk e rs6 exam ined clinical evid en ce from 20 o rth o d o n tic p atien ts b ased on o ne pre- a n d tw o p o sttre a tm e n t m e a su rem en ts

(ten years apart). A m o n g th e ir findings w ere a 0.23 correlatio n coefficien t b e tw e e n calcu lated P o n t’s ideal in terp rem o la r w idth a n d actu al in­ terp rem o lar w idth o f c a sts te n y e a rs a fte r re ta in ­ ing devices had b e e n u sed ; a n d a 0.20 c o rrela­ tion b e tw ee n calcu lated P o n t’s ideal in te rm o la r w idth w ith th e a ctu al in te rm o la r w idth te n y ears later. T h e in v estig ato rs6 in d icated th a t th e original values fo r th e in te rp re m o lar an d in term o lar arch w idths pro v id ed a m u ch m o re reliable p red ic­ tion o f th e ultim ate stab le arc h -w id th m e a su re ­ m ents th an P o n t’s index. E x tre m e v ariatio n s b e tw ee n ob serv ed w idths an d th o se calcu lated from P o n t’s fo rm ula w ere n o te d also. T h e a u th ­ o rs indicated th a t m e asu rem en ts d e riv ed fro m P o n t’s index w ere o f “ no v alu e in p red ictin g u ltim ate arch w id th ” in th e a re a s o f th e m axil­ lary in terp rem o lar and in te rm o la r d istan c es.

M e th o d

T o illu strate th e im p lications o f neglecting th e n otion o f v ariatio n a b o u t a m ea n in th e co n te x t o f P o n t’s index, m e asu rem en ts o f m axillary in­ te rp rem o la r w id th s, in te rm o la r w id th s, an d m ax­ illary cen tral and la te ra l in c iso r w id th s a t c o n ­ ta c t points w ere m ade on 40 N a v a jo fem ales (ages 11 to 21), 51 N a v a jo m ales (ages 11 to 21), an d 133 U n iv e rsity o f M in n e so ta d e n ta l stu ­ d e n ts (m en, ages 19 to 25). T h e p a rtic ip a n ts had ideal occlusions w ith cro w d in g o r spacing w ithin th e arch es o f less th a n 1 m m . T h e in te rarc h w idths b etw een th e p re m o la rs and m olars o f th e ideal occlusions w ere m ea su re d w ith a sh arp ­ ened B oley gauge; th e gauge w as p laced b e ­ tw een cen tral g rooves o f th e first p re m o lars, and b etw een the c e n tra l p its o f th e first m olars. T h e B oley gauge also w as u se d to m e asu re th e m esiodistal w idths o f th e m axillary c e n tra l and lateral incisors. A ll m e a su re m e n ts w ere m ade by o n e exam iner. T h e co m b in ed in c iso r w idth ob­ tain ed w as u sed in P o n t’s fo rm u la to calcu late th e in terp re m o lar an d in te rm o la r a rc h w idths (m o la r= 2 I x 100/64; p r e m o la r= S l x 100/80.) T h e m easured in tera rch w id th s b etw e en th e u p p e r right and left first p re m o la rs an d th e in ter­ arch w idths b etw e en th e u p p e r right and left first m olars w ere co m p ared w ith w idths calcu lated w ith u se o f P o n t’s index. T h e d ifferen ces o r e r­ ro rs betw een the o b serv e d a n d c alcu la ted w idths th en w ere p lo tted (F ig 1-4). T h e vertical c o o rd in a te in d icate s th e differWorms—others: PONT'S INDEX AND DENTAL ARCH FORM ■ 877

N-5I Navajo 0-» Observed > Calculated * + N=40

Navajo O* Observed > Calculated * +

width

width

interpremolar width

Intermolar width

Fig 1 ■ Difference between observed interpremolar (4-4) and intermolar (6-6) widths and widths calculated by Pont’s index in Navajo females.

Fig 2 ■ Difference between observed interpremolar (4-4) and intermolar (6-6) widths and those calculated by Pont’s index in Navajo males.

en c e in m illim eters. T h e positiv e n u m b ers indi­ c a te th a t th e o b serv ed w idths w ere g re a te r th an th e c a lc u la ted w id th s. T h e m e a su re m e n ts o f th e a rc h e s a re re c o rd e d in tw o v ertical co lu m n s and co rre sp o n d to th e d ifferences b e tw e e n th e o b ­ serv ed an d calcu lated w idths o f th e first p re ­ m o lars an d o f th e first m olars. T h e re sp e c tiv e differen ces a re c o n n ected w ith a straig h t line. T h u s, th e d ifferen ces b e tw e e n th e c alcu lated m e a su re m e n ts an d o b serv ed m e a su rem en ts o f each d en tal a rc h can b e visualized quickly.

straight line o n th e h o riz o n ta l c o o rd in ate. Id en tica l m ea su rem en ts to th o se calcu lated w ith P o n t’s index w e re fo u n d fo r n o n e o f th e p articip an ts. V aria tio n b e tw e e n o b se rv e d and calculated m easu re m en ts ra n g ed fro m - 1 2 .5 to + 9 .8 m m in th e p re m o la r w idths and fro m —15.1 to + 14.7 m m fo r th e m o la r w idths. M o st o f th e p a rtic ip a n ts h a d a n eg ative dif­ fe re n ce, th a t is, th e o b se rv e d m ea su re m e n t w as less th a n th e c alcu lated m ea su rem en t. T h is sug­ gests th a t th e N a v a jo w o m en (F ig 1) had n ar­ ro w e r arc h es o r in te rto o th d ista n ce s th a n th o se calculated w ith P o n t’s in d ex . F ig u re 2 show s th a t th e N a v a jo m ales w e re divided m ore evenly ab ove and below th e h o rizo n ta l co o rd in ate. T h is suggests th a t, fo r a v era g e m easu rem en ts, P o n t’s index nu m b ers w e re d eriv ed fro m a sam ­ ple th a t closely rese m b le d th e N a v a jo m ale group. F o r in sta n c e , th e N a v a jo fem ales w ould h av e an index n u m b er o f xXI x 100/x p rem olar = 32. l_x 100/37.07=87 fo r th e p re m o la r w idth, and x S I x 100/x m o la r= 3 2 .1 x 100/47.78=67 fo r th e m olar w idth. T h e se larg er index num bers w ould h av e th e effect o f narro w in g o r reducing th e calculated arch w idth. T h e range o f th e dif-

R e s u lt s

a n d

d is c u s s io n

E x am in atio n o f th e figures rev eals a g re a t deal o f e rro r in h e re n t in th e u se o f P o n t’s index as it re la te d to th e se ideal occlu sio n s. I f th e re w ere no d ifferen ce an d th e o b serv ed m e a su re m e n t in fa c t eq u aled th e calcu lated m e a su re m e n t, all th e c o n n ectin g lines w ould a p p e a r on th e h o ri­ zo n tal c o o rd in a te , w ith b o th m e a su re m e n ts h a v ­ ing z e ro d ifferen ce. T h e line co n n ectin g th e p re ­ m o lar an d m o lar m e a su rem en ts w ould b e a 878 ■ JADA, Vol. 85, October 1972

N=63

interpremolar width

Dental

N=70

Dental

0*

O*

intermolar width

interpremolar width

intermolar width

Fig 3 ■ Difference between observed interpremolar (4-4) and intermolar (6-6) widths and those calculated by Pont’s index in part of the sample of male dental students.

Fig 4 ■ Difference between observed interpremolar (4-4) and intermolar (6-6) widths and those calculated by Pont’s index in the remainder of the sample of male dental students.

feren c e b e tw e e n th e o b se rv e d an d calcu lated m ea su re m e n ts w ould rem ain th e sam e, b u t th e p artic ip a n ts w ould b e divided m o re ev en ly on b o th sides o f th e h o riz o n ta l co o rd in ate. T h e d e ­ riv atio n o f d ifferen t in d ex n u m b ers in d icates a differen ce b e tw e e n fem ale an d m ale N a v a jo arch w id th s; th e N a v a jo m ale, on th e av erag e, has w id er a rc h e s th a n th e N a v a jo fem ale. F ig u res 3 an d 4 show m e a su re m e n ts fo r th e den tal stu d e n ts. M o st differen ces a re on th e negativ e side. A g ain , th is in d icates th a t a larg er index n u m b e r w ould b e n eed ed to b a la n c e th e d istrib u tio n o f th e d ifferen ce a b o v e an d b elo w th e h o rizo n tal c o o rd in ate. T h is is a n o th e r ex ­ am ple o f eth n ic d ifferen ces p o in ted o u t b y P o n t5 and K o rk h a u s .7 In F ig u res 1 th ro u g h 4, m o st lines th a t c o n ­ n ec t th e o b serv ed p re m o la r an d m o lar m e a su re ­ m ents o f ea c h p a rtic ip a n t a re n o t h o riz o n ta l. I f this line w ere h o rizo n tal (for ex am p le, p a rtic i­ p a n t A -B in F ig 1), th e d ifferen ce b e tw e e n th e calcu lated an d th e m easu red w id th s fo r b o th th e p rem o lars an d m olars w ould b e eq u al, in d icat­ ing a c o n siste n t a rc h fo rm . In F ig u re 5, b-b' an d d -d ' d e m o n stra te th e a rc h fo rm th a t o ccu rs if th e

m olar difference equals th e p re m o la r d ifference. T his re su lts in an arch fo rm rese m b lin g th a t cal­ cu lated by P o n t’s index (fo r ex am p le, F ig 5, c-c). T h is arch fo rm can e x ist in a n infinite num ­ b e r o f v ariatio n s in th e d irec tio n o f b -b th a t is larger, o r d -d ' th a t is sm aller th a n th e a rc h fo rm calcu lated by P o n t’s index. H o w e v e r, no co n ­ sisten cy o f arch fo rm e x isted . T h e v ariatio n in arch fo rm s is n o t co n sid ered w h en P o n t’s index is u sed. M o st p articip an ts had v a rio u s d ifferen c es b e­ tw een th e p rem o lar and m o la r m ea su re m en ts. I f the line from th e p re m o la r to th e m o lar asc e n d s (for exam ple, F ig 1, E -F ), th e o b se rv e d arch form is m ore tap erin g th a n th e c a lcu la ted a rc h form . In F ig u re 5, a-a sh o w s th e m o re ta p erin g arc h form th a t o c cu rs if th e m o lar differen ce is m ore po sitiv e th a n th e p re m o la r d ifference. A rch a -a ’ ca n ex ist in v a rio u s d eg ree s o f d ev ia­ tion from th e calcu lated fo rm , b u t all th e arch e s will b e tap ere d . T h e deg ree o f in c re a se d ta p e r­ ing is d irectly p ro p o rtio n al to th e in creased slope o f th e ascen d in g co n n ec tin g line. C o n ­ versely , a d escending line co n n ectin g th e p re ­ m olar an d m olar d ifferen ces (for ex am p le, F ig 1, Worms—others: PONT’S INDEX AND DENTAL ARCH FORM ■ 879

range of error mm

Fig 5 ■ Variation of arch form presented by participants when the differences between the calculated and observed interpre­ molar and Intermolar widths are equal, b-b' or d-d'; unequal, a-a' or e-e'; and no difference, c-c. C -D ) in d icates a relativ e n arro w in g in th e o b ­ se rv e d m o lar w id th and a w idening in th e o b ­ serv e d p re m o la r w id th (for exam p le, F ig 5, e-e). T h is fo rm w o u ld b e m o re ovo id o r sq u are th an th e c alcu lated on e. T h e ste e p e r th e a sc e n t or d e s c e n t o f th e co n n ectin g lin e, th e m o re exag­ g e ra te d th e d ev iatio n o f th e actu al a rc h form fro m th e calcu lated arch form . T h e ra n g e o f th e d ifference b e tw e e n th e actu-

Navajo 0-» N= 51 45-

mm

2 40 S a 0

1

35

O 30

al and th e c alcu lated a rc h form illu strates th e g rea t fallacy o f arch -w id th p red eterm in atio n . P o n t’s index is a m ean m easu re m e n t o f a group and th is index applies w ell to a d iscussion o f th e group. T h e av erag e , h o w e v er, does n o t apply to th e individual. F ig u re 6 show s a sam ple scatterg ram fo r com ­ p a riso n o f th e co rre latio n b etw een calcu lated and o b serv e d in terp rem o lar w idths. T h e solid line A -B in d icates p e rfe c t co rrela tio n ( r = l) . O nly tw o p e rso n s a re in this category. T h o se in d icated b elo w th e line h a v e o b serv ed in te rp re ­ m olar a n d in te rm o la r m e asu re m en ts th a t a re less th a n th e calcu lated m easu rem en ts. T h o se p e rso n s in d icate d ab o v e th e line h av e o b serv ed m ea su rem en ts th a t a re g re a te r th a n th e calcu lat­ ed m ea su rem e n t. I f th e calcu lated interp rem o lar w idth w e re being u se d in a tre a tm e n t plan w ith disreg ard fo r a rc h form , th e arch e s o f m o st p e r­ sons w ould b e e ith e r over- o r u n d e re x p an d ed . E v e n if an e rro r o f ± 1 m m w ere accep tab le, a sm all p e rc e n ta g e o f p a rtic ip an ts w ould b e in­ d icated w ithin this to le ra n c e a re a fo r b o th m ea­ su rem en ts. A n ex am ple o f this can b e seen in F ig u re 2 o f th e N a v a jo m ales. O nly th re e p e r­ so n s, o r a b o u t 5% , h av e d ifferences b etw een th e o b serv ed an d calcu lated m easu rem en ts o f ±1 m m o r less fo r b o th in te rp rem o la r and in term olar w idths. C o rrelatio n s o f coefficients a re p re se n t­ ed in th e T ab le. O th e r fa c to rs also a re involved in arch-w idth determ in atio n . S keletal p a tte rn s h av e been show n to b e im p o rtan t in arch -w id th relatio n ­ ships. N a sb y and c o -w o rk e rs8 suggested th a t individuals w ith high m an d ib u lar planes had m o re crow ding, cam e fo r tre a tm e n t m o re fre­ q u en tly , and h a d m uch n a rro w e r arch w idths. C o n v erse ly , individuals w ith low m andibular p lan es h a d w id er a rc h e s, less crow ding, and cam e less fre q u en tly fo r tre atm e n t. T h e c o n c e p t o f a rc h ex p an sio n to acco m m o ­ d a te cro w d ed te e th is a n a c cep ted treatm en t plan. E x p an sio n o f den tal a rch es is accom plished

Table ■ Correlation coefficients (r) between the calcu­ lated and observed interarch widths. No.

25-

40

25

30

35

40

45 mm 51

Group

Fig 6 ■ Scattergram showing the correlation between observed and calculated Interpremolar widths of Navajo males. 880 ■ JADA, Vol. 85, October 1972

r

Navajo females Interpremolar Intermolar

0.13 0.17

Interpremolar Intermolar

0.24 0.06

Interpremolar Intermolar

0.25 0,28

Navajo males

Calculated Prem olar Width 113

Interarch width

Dental students

easily w ith v ario u s ap p lian ce tec h n iq u e s, b o th rem o v ab le an d fixed. W h e th e r an arch can o r can n o t b e e x p a n d e d o r h ow it should b e acco m ­ plished is acad em ic. T h e p o in t is th a t tre a tm e n t plannin g in v o lv es o th e r v ariab les, such as to o th size, sk eletal p a tte rn s, axial in clin atio n s, ap ­ p e a ra n c e , a n d p o s ttre a tm e n t stability. B ecau se all th e se v ariab le p a ra m e te rs in te ra c t, th e use o f an a rb itra ry index fo r individuals is p reclu d ­ ed.

C o n c lu s io n

L o w c o rre la tio n ex ists b etw een arch p re d e te r­ m inatio n w ith u se o f P o n t’s index o r sim ilarly deriv ed in d e x e s an d o b se rv e d a rc h form s. T h is suggests th a t its u se a s a clinical to o l fo r indivi­ du al tre a tm e n t plan n in g is unjustified. M ea n a rc h fo rm m ay v ary b e tw e e n ethnic gro u p s an d a rc h form v aries b etw een individuals. D ifferen ces in averag e a rc h form m ay exist b e tw ee n se x e s w ithin an e th n ic group.

Drs. Worms, Speidel, and Isaacson are on the faculty of the division of orthodontics, and Dr. Meskln is in the division of health ecology, School of Dentistry, 221 Owre Hall, University of Minnesota, Minneapolis, 55455.

1. Davenport, I.B. The significance of the natural form and arrangement of the dental arches of man, with a consideration of the changes which occur as a result of their artificial derange­ ment by filling, or by the extraction of teeth. Dent Cosmos 29:413 July 1887. 2. Angle, E.H. Classification of malocclusion. Dent Cosmos 41:248 March 1899. 3. Bonwill, W.G.A. Geometrical and mechanical laws of the articulation of the human teeth—the anatomical articulator; system of an all-porcelain crown substitution. In Litch, W.F., ed. The American system of dentistry. Philadelphia, Lea Brothers & Co., 1887, vol 2, p 486. 4. Hawley, C.A. Determination of the normal arch, and its ap­ plication to orthodontia. Dent Cosmos 47:541 May 1905. 5. Pont, A. Der Zahn-Index in der Orthodontie. Z Zahnarztl Orthopädie 3:306, 1909. 6. Joondeph, D.R.; Riedel, R.A.; and Moore, A.W. Pont’s in­ dex; a clinical evaluation. Angle Orthod 40:112 April 1971. 7. Korkhaus, G. Biomichanishe Gebiss-und Kieferorthopadie. In Hotz, R. Orthodontia in everyday practice. Philadelphia, J. B. Lippincott Co., 1961, p 63. 8. Nasby, J.A., and others. Orthodontic extractions and the facial skeletal pattern. Angle Orthod 42:116 April 1972.

Foley's Footnotes As the dental journals of the nineteenth century published not only the texts of the papers presented before various meetings but also the remarks made by the discussants, the observant reader is prompted to form summary opinions about the con tent and style of hundreds of speakers. This reader was particularly impressed by one characteristic of style: the interlarding of quotations. The ability to quote poetry was then considered to be a reflection of cultural achievement and obviously the quo­ tations were used for display as well as for pertinent application. The dentist-quoters chose the majority of their lines from four sources: Polonius’s advice to Laertes (H a m le t: Act I, scene 3); lago’s speech on his “good name" (O th e llo : Act III, scene 3); Longfellow’s “ A Psalm of Life” ; andRudyard Kipling’s“ L’Envoi.” Eventually such oft repeated lines as “Take each man’s censure, but reserve thy judgment,” “ Good name in man and woman . . . is the immediate jewel of their souls,” “ Lives of great men remind us/We can make our lives sublime,” and “ When Earth’s last picture is painted, and the tubes are twisted and dried” began to be platitudes. As Petroleum V. Nasby, the popular American humorist, wrote a century ago: “ | he^ notist that it don’t make much difference wat thecotashun is, so ez you end a remark with acotashun." G a rd n e r P . H . F o le y

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