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Porcelain Technic as It Relates to the Inlay*
V e h e — P o r c e la in T e c h n i c as i t R e l a t e s to t h e I n l a y inlays are indicated. T h e y are plainly indicated in a ll buccal cavities, especially in lo w er m olars an d bicuspids. I t is h ea rt b reaking to see la rg e gold inlays in these cavities in m olars th a t already have been filled to the lim it w ith mesioclusodistal gold inlays. I n m ost o f these cases, th e rm a l changes do th e ir deadly w ork, an d sooner o r la te r the tooth is lost. Jo h n J . T ra v is , o f A n n A rb o r, has alread y sounded the a la rm , an d in his late papers is crying out against the ru th less c u ttin g o f the first m olars o f the young and the insertion o f larg e gold inlays. I t w as to this th a t he attrib u ted m uch o f the trouble fo u n d in the m ouths o f patients u n d e r 20 years o f age. L a rg e restorations o f synthetic cem ents are as dangerous as la rg e gold inlays, and it w o u ld then seem th a t
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porcelain should be used in p referen ce to a ll o th e r m aterial. T h e old a rg u m e n t th a t porcelain is the nearest to the n a tu ra l fillin g an d th a t it protects the pulp fro m th e rm a l changes holds ju st as good today as it ever did, an d a w ell-fitted inlay set in a good q uality o f cem ent is b etter th an a ll the synthetic m aterials m ade up to date. T h e use o f inlays in incisors either upper o r lo w er should be governed by the condition o f th e teeth in w hich they are placed. L a rg e ap proxim al cavities in these teeth in w hich sufficient room can be p ro cu red m ay be b e a u tifu lly an d sa fe ly restored w ith an inlay. T h is also applies to bicuspids in eith er ja w , an d w here th ere is room enough fo r the m ateria l, m esioclusodistal restorations can be sa fe ly m ade.
P O R C E L A IN T E C H N IC A S IT R E L A T E S T O T H E IN L A Y *
By W. D. VEHE, D.D.S., Minneapolis, Minnesota H E fa ilu re to use porcelain in d en tistry g en erally is la rg e ly due to the prev ailin g b elief th a t it is m ore difficult to m anipulate th a n other fillin g m aterials an d th a t it requires a special aptitude on the p a rt o f the opera tor. T h is b elief seems to be so th o r oughly in g rain ed into the very fiber o f the profession th a t the younger m en dare n o t m ake an atte m p t f o r fe a r o f fa ilu re an d discouragem ent. An analysis o f this hypothesis does n o t bear o ut this co n ten tio n ; f o r w hen a com
T
* R e ad b e fo re th e Section on O p erativ e D e n tis try a t th e S eventh I n te rn a tio n a l D e n ta l C ongress, P h ila d e lp h ia , P a ., A u g . 25, 1926.
parison is m ade o f p o rcelain technic w ith th a t o f o th e r fillin g m aterials, it m ust becom e ev ident th a t the basis f o r a m astery o f it is the same. T o one fa m ilia r, f o r instance, w ith the cast go ld in lay an d n o t w ith porce lain , the desire to appreciate an d u n d e r stand f u lly the req u irem en ts th a t porcelain m akes w hich g o ld does n o t im pose suggests itse lf. W ith this th o u g h t in m ind, it m ust be ad m itte d th a t the phys ical requirem en ts o f these m aterials are not the sam e, w h ile the m an ip u lativ e re quirem ents are the same in degree even though n o t in kind. T e c h n ic , in this instance, is m erely the procedure in
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T h e Journal o f the Am erican D ental Association
volved to m anipulate these m aterials to m eet certain requirem ents an d to pro duce definite results in the m o u th ; and,
Fig.
1
.— Cavity on labial surface.
as it is to be p erfec ted in the w o rk in g o f gold, it could be done as easily. T h e difficulty even today is th a t so m any are
Fig. 3.— Cavity on buccal surface.
view ed fro m this an g le, it m ust be ob served th a t either procedure is larg ely and p rim arily a m astery o f details. I t is not to be denied th a t porcelain imposes exacting requirem ents on the operator, but one m ust ad m it the same
not th o ro u g h ly proficient in the m anip ulatio n o f gold, an d can these same m en be expected to do any b etter w ith porcelain? I t seems impossible to an tici pate this in view o f the fa c t th a t the req u irem en t fo r porcelain is more
Fig. 2.— Cavity on labial surface.
Fig. 4.— Cavity on proximal surface.
o f gold. T h e re is a n a tu ra l p referen ce f o r gold as com pared w ith porcelain. W e re it as necessary to m aster porcelain
lim ited . N a tu ra lly , practice leads to p erfectio n , an d i f the o perator is n ot forced to m ake an accurate procedure
V ehe— Porcelain Technic as it Relates to the Inlay
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m ore or less autom atic by a repetition o f it, he w ill n o t succeed unless he has the desire and the persistence to w o rk out a technical perfectio n .
also as regards the n a tu ra l requirem ents o f the m aterials o f w hich the in lay is to be m ade. C av ity p reparation fo r the porcelain in lay does not differ m uch
Fig. J.— Cavity on proximal surface.
Fig. 7.— Cavity on proximo-incisal surface.
O bviously, the object o f the inlay is a restorative one, an d in replacing lost tooth stru ctu re, porcelain meets the added requirem ent o f esthetics. In de signing such a replacem ent o f tooth
fro m th a t f o r a m etal inlay, except in a fe w details, an d these differences are m ade necessary by the physicial req u ire m ents o f porcelain. I n the one su rface cavities, w h eth er
Fig. 6 .— Cavity on proximal surface.
Fig. 8.— Cavity on proximo-incisal surface, labial view.
stru ctu re, several facto rs n a tu ra lly are involved, n o t alone as they p ertain to th a t portion o f the tooth rem ain in g , but
on the labial or the buccal surfaces (F ig s. 1— 3 ) or on proxim al surfaces
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o f the a n te rio r teeth (F ig s. 4— 6 ) , the preparation o f the c a v i t y sim ulates closely th a t fo r the m etal inlay. G ood depth is necessary f o r good color and anchorage, an d all w alls should be cut to m eet the surface o f the tooth a t a rig h t angle. T h is precaution should be observed in a ll preparations f o r porce lain , so th a t the porcelain as w ell as the enam el m argins w ill receive all pos sible protection. W h e re the cavity ex tends into the dentin, these w alls m ay be
W h e n separation o f the teeth w ill not provide fo r this, the preparation m ust be m ade w ith this in m in d as w ell. W h e n the incisal or occlusal su rfaces are in volved (F ig s. 7— 1 1 ), the condition at once becomes m ore serious an d com pli cated. H ere, the am o u n t o f the tooth involved, an d the severity an d extent o f the o cclu d in g stresses, very largely govern the preparation. G ood depth w ith sufficient bulk to w ith stan d these stresses is, o f course, im p o rtan t, an d the
Fig. 9.— Cavity on proximo-incisal surface, lingual view.
Fig. 10.— Cavity on proximo-incisal sur face, lingual view.
m ade p arallel, and the base o f the cavity should sim ulate the original contour o f the tooth. T h e cavity outline is gov erned by the am o u n t o f tooth structure th a t is involved, o f course, but the operator should adhere to g rac efu l curves ra th e r th an sharp angles, n o t only fo r esthetic reasons but also because o f the g re a te r ease in adapting the m atrix. A ll w alls should be planed sm oothly, an d the m argins should be sharply de fined. I n proxim al cavities, accessibility fo r m ak in g the m a trix an d fo r setting the w ork m ust be a vital consideration.
m arg in s should n ot be placed directly w here the occluding teeth w ill strike them . M a trix m ak in g n a tu ra lly fo llo w s the cavity p reparation, an d f o r this purpose, p latin u m , gold an d platinous gold foil, in various thicknesses b ut usually o f one one-th o u san d th o f an inch, are used, de p en d in g on the fu sin g point o f the p orcelain an d also on the desire o f the operator. T h is m a trix m ay be m ade in one o f three g en eral w ays: ( 1 ) directly, fo rm in g the m a trix in the tooth cavity; ( 2 ) in d irectly , fo rm in g the m atrix either on the im pression o f the cavity
Vehe— Porcelain Technic as it Relates to the Inlay or on a die o f this cavity; ( 3 ) in directdirectly, fo rm in g the m a trix a t least quite accurately on a die o f the cavity an d th en reburn ish in g it in the tooth cavity. T h e m a trix m ay be m ade in any o f these w ays, depending on the location o f the cavity an d the wishes o f the oper ator. T h e object alw ays is to m ake it en tirely accurate an d to keep it so until the w o rk is com pleted, and how this is done does n o t m a tte r as lo n g as
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beyond the orifice o f the cavity fo r several m illim eters a t least. T h is is necessary so th a t the m a trix w ill not become distorted easily in the fu sin g process a n d to fac ilita te the proper con to u rin g o f the w o rk in bu ild in g . T o shape the m atrix , the m aterial should be placed over the cavity, an d w ith the aid o f sm all pellets o f cotton, spunk or some such m a terial u n d e r a suitable burnisher, it should be w orked into the deeper parts o f the cavity by stretch in g the m e tal b efo re it is fo rced over the surfaces o f the tooth. T h e m etal should be stretched as c a re fu lly an d as
Fig. 12.— Extent o f cervical color worked out. Fig. 1 1.— Cavity on proximoclusal surface. the o p erator does it in th e easiest w ay f o r h im se lf a n d his p atient an d in the shortest tim e. Possibly, th e m ost m atrices are m ade by the d irect m ethod, an d w here there is good access to a cavity on a su rface o f a tooth th a t w ill p erm it the m a trix to be held firm ly d u rin g the b u rnishing proc ess, it is the quickest an d , a t the same tim e, the m ost accurate m ethod. A t least, there is no w ay o f doing it any m ore ac cu rately th a n this. I n burnishing a m a trix directly, it is desirable to have the fo il w ell an n ealed an d o f the proper size. I t should be la rg e enough to project
m uch as possible, an d care should be taken n o t to allo w fo ld s to come into it. L astly , the fo il should be fo rced over the su rface o f the tooth only a f te r the cavity portion has been w orked in a n d th en the m ore accu rate burnishing should be com pleted. F o r this la tte r burnishing, the m a trix should be held rig id ly w ith the aid o f suitable m ate rial such as C h in a silk cu t in to strips, o r some sort o f tape o f silk o r cotton, o r even rubber dam . P erhaps o f these m aterials com m on silk seam binding th a t m ay be obtained a t the notion coun te r o f any dry goods store is as suitable as an y th in g . A t this point, it is g enerally w ell to an n eal the fo il in the flame o f
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a blow pipe, a f te r w hich the final burn ish in g is done. A last inspection should show an en tirely accurate re p roduction of. the cavity in every detail. T h e r e should be no folds no r tears at the cavity m argins an d it should have a sm oothness corresponding to th a t o f the cavity an d tooth surface. Sticky w ax th a t w ill b u rn off cleanly m ay be used to fac ilita te the rem oval o f the m a trix w ith o u t distortion. A m a trix m ay be m ade in d irectly either over an im pression o f a cavity or on a die o f the cavity. T h e r e is a
the cavity portion upperm ost, a f te r w hich the m a trix is m ade in the usual w ay. T h e difficulties th a t m ay be en countered in this process are tears at the m arg in s ju st w here they m ust not be. T h is can be avoided by c a re fu lly tu ck in g the fo il into the deeper por tions even w ith the fo ld s b efo re sw aging it dow n to place. I n this m a trix , fo ld s do n o t m a tte r, an d the req u irem en t is th a t the inside o f the m a trix correspond in sm oothness w ith th a t o f the cavity. T h e technic fo r m ak in g a m a trix ind irectly is w ell k now n an d need n ot
Fig. 13.— Outline of incisal color.
Fig. 14.— Completed color diagram.
d istinct advantage in m aking it over an im pression o f a cavity in the class o f cavities w ith fo u r w alls, such as the labial, buccal an d some proxim al cav ities; fo r, in d oing so, the inside o f the m a trix corresponds to the cavity size an d outline ra th e r th an to the outside o f it, a n d the thickness o f the foil has n o th in g to do w ith the fit o f the com p leted inlay. T h e technic fo r this p ro cedure is m in u tely exacting but not difficult. T h e im pression o f the cavity m ay be obtained in a good cem ent, and the m a trix is then m ade thereon. T h e best procedure consists in m ak in g the im pression in casting w ax an d casting this im pression in gold. T h is casting is th en m ounted in a sw aging base w ith
be considered here. I t corresponds to the d irect m ethod except th a t because the m a trix is m ade out o f the m o u th , it is m ore easily and quickly done. T h e in d ire ct-d irec t m ethod is in d icated in the m ore difficult cases in w hich the operator wishes to fo rm the m a trix m ore or less accu rately on a die m ade o f ce m en t, usually, an d th en reburnish it in the tooth cavity. T h e color problem should be care fu lly taken up a t the com pletion o f the m atrix , or the im pression o f the cavity i f the m a trix is to be m ade in d irectly . N o m a tte r how accurate the inlay may be w hen com pleted, if the color is w ro n g or i f it violates the esthetic fe a tu re in this respect, it m ust be co n
Vehe— Porcelain Technic as it Relates to the Inlay sidered a fa ilu re . Because color m eans so m uch in the inlay, it is necessary th a t it receive c a re fu l consideration. T h e principle o f color in terp retatio n in porcelain is the same in the inlay th a t it is in the veneer crow n except th a t we are d ea lin g w ith but a p a rt o f a tooth cro w n an d w e have reflection and re fra ctio n o f lig h t to deal w ith to a g rea ter extent. H o w ev er elusive this problem m ay appear to be to the b e g in ner, it should nev er be m ysterious, fo r the color problem can be w orked out to be as scientific and as accurate as any
Fig. 15.— Cross-section of color scheme. p art o f the procedure. T h e first req uisite is a color guide th a t accurately represents the colors o f the porcelain w ith w hich w e are w o rking. T h is m eans th a t the m a n u fa c tu re r’s color guide m ay n o t be rig h t. W ith this, th en , as a beg in n in g , w e m ust le arn to see the colors in the tooth as they really are an d th en m atch them w ith the colors on the color guide. I t is best to diagram the color requirem ents o f each case on a suitable card. T h is d iagram may consist o f a sketch o f the labial or buccal o utline o f the tooth to be treated , w ith the ex tent o f the involvem ent an d the color requirem ents accurately w orked out. (F ig s. 12— 1 5 .) Such a record has m any advantages an d m ay include,
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aside fro m this color d iag ram , m easure m ents to assist in b u ild in g the w ork, stain in g in fo rm a tio n an d any o th e r data th a t m ay be o f help. W h e n a preparation is properly m ade, a n d an accurate m a trix obtained, an d the color req u irem en ts are exactingly w orked out an d recorded, the b u ild in g o f the inlay should n o t be difficult. N a tu ra lly , g re a t care m ust be exercised constantly n o t to d isto rt the m atrix d u rin g the process o f b u ild in g th e w ork. Provision m ust also be m ade to prev en t distortion d u rin g the fu sin g o f the
Fig. 16.— Color requirements for the inlay. porcelain. T h e la tte r effect can be pre vented by investing the m a trix , o r as is usually done, by p ain tin g a th in solution o f shellac in alcohol on the w alls f a r thest fro m the cen ter o f the m a trix or a t the points w here the m ost severe con trac tio n w ill take place. O th e r m ethods are used to obviate this possibility, such as c u ttin g the porcelain a f te r it is bu ilt w ith a sharp lance in th e fo rm o f the le tte r X or b u ild in g the porcelain to f u ll co n to u r w ith o u t covering the w alls o f the m a trix . I t seems th a t the shellac m ethod is the accepted one because it allow s f u ll co n to u rin g a t each b u ild in g an d it likew ise is the m ore positive. T h e shellac is only applied b efo re the first contouring.
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I n w o rk in g the porcelain, care should be taken to w o rk out all air an d to keep it clean. A ng les an d grooves m ust be em phasized an d an am o u n t m ay be a llo w ed f o r contraction in fu sin g , but aside fro m this, the w o rk should not be o vercontoured, n o r should porcelain be b u ilt over the m a rg in o f the fo il. T h e cervical an d incisal colors should be properly placed f o r co rrect color effects a t each contouring. U sually, three fu s ings are sufficient to com plete an inlay an d overbiscuiting or o v erfu sin g g en era lly are fa ta l to a good result. Ju st b efo re the last conto u rin g , the inlay m ay be tried in the m o u th to v erify co ntour, contact an d occlusion in the m ore difficult cases, a n d it is also best to dress dow n the m a rg in o f the foil w h ile it is in th e tooth o r in the m etal die w ith suitable sm all tru e ru n n in g stones. T h is dressing dow n is n o t done q uite so f a r w h en m ak in g the m a trix on a n impression. A f te r this fin al fu sin g , the fo il is rem oved an d the cavity su rface o f the inlay should be roughened to obtain g re a te r adhesion o f the cem ent. T h is m ay be done w ith a suitable stone or d iam ond disc, o r w ith hydrofluoric acid. T h e w o rk should be c a re fu lly set; otherw ise, a p e rfe c t restoration m ay be ru in ed in a m o m en t by fra c tu rin g a m a rg in . T h e selection o f a proper ce m e n tin g m edium m ay be som ew hat o f a problem , since the silicates have come to supplant, at least partly, the use o f the oxyphosphate cem ents fo r this purpose. As the silicates have not am ple tim e to dem onstrate th e ir com plete reliability f o r the cem entation o f this w ork, i f one is perm itted to ju d g e th e ir usefulness g enerally, one can n o t rest w ith com plete assurance in
th e ir use. I t is hoped th a t the n ew er cem en tin g m edium s w ill live up to our expectations o f th em , as the color ad vantage in the porcelain a f te r place m e n t is so m uch superior to w h a t we have had to contend w ith th a t the operator has every opportunity to be com e enthusiastic. I n cem en tin g w ith w h atev er m edium , the w o rk should be held in place firm ly u n til the cem ent has become set quite w ell o r u n til there is little d an g e r o f the in lay being moved. I t is n ot de sirable to rem ove all o f the cem en t at this tim e, b ut at a fu tu re sittin g , the m a rg in should be finally com pleted by ru n n in g over th em w ith a suitable sm all A rkansas stone u n d er w ate r, an d the occlusion should be checked again. T h is , th en , com pletes the operation, and w h eth e r it is a sim ple one su rface restoration or one th a t is m ore com pli cated, it m ust be p lainly evident th a t the procedure is larg ely m ade up o f care f u lly w ork ed o ut details. P erhaps m any o f us in attem p tin g such an operation have the w hole mass o f detail in m in d , w ith m ore or less confusion to o u r selves w h en w e should be confined to but one an d allo w the next one to come in n atu ra lly . I t is b ut logical to reason th a t each step should be c a re fu lly co m pleted in the procedure b efo re the suc ceeding one is attem p ted , fo r a good result, an d w hen one fo llo w s th ro u g h an operation in this m a n n er, there can be b u t one resu lt; nam ely, a restoration th a t is the highest expression o f the re storative a rt, an d i f it has been properly selected, it w ill be a source o f satisfac tion to the operator and o f gratificatio n to the patient.
823 Nicollet Ave.
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porcelain should be used in p referen ce to a ll o th e r m aterial. T h e old a rg u m e n t th a t porcelain is the nearest to the n a tu ra l fillin g an d th a t it protects the pulp fro m th e rm a l changes holds ju st as good today as it ever did, an d a w ell-fitted inlay set in a good q uality o f cem ent is b etter th an a ll the synthetic m aterials m ade up to date. T h e use o f inlays in incisors either upper o r lo w er should be governed by the condition o f th e teeth in w hich they are placed. L a rg e ap proxim al cavities in these teeth in w hich sufficient room can be p ro cu red m ay be b e a u tifu lly an d sa fe ly restored w ith an inlay. T h is also applies to bicuspids in eith er ja w , an d w here th ere is room enough fo r the m ateria l, m esioclusodistal restorations can be sa fe ly m ade.
P O R C E L A IN T E C H N IC A S IT R E L A T E S T O T H E IN L A Y *
By W. D. VEHE, D.D.S., Minneapolis, Minnesota H E fa ilu re to use porcelain in d en tistry g en erally is la rg e ly due to the prev ailin g b elief th a t it is m ore difficult to m anipulate th a n other fillin g m aterials an d th a t it requires a special aptitude on the p a rt o f the opera tor. T h is b elief seems to be so th o r oughly in g rain ed into the very fiber o f the profession th a t the younger m en dare n o t m ake an atte m p t f o r fe a r o f fa ilu re an d discouragem ent. An analysis o f this hypothesis does n o t bear o ut this co n ten tio n ; f o r w hen a com
T
* R e ad b e fo re th e Section on O p erativ e D e n tis try a t th e S eventh I n te rn a tio n a l D e n ta l C ongress, P h ila d e lp h ia , P a ., A u g . 25, 1926.
parison is m ade o f p o rcelain technic w ith th a t o f o th e r fillin g m aterials, it m ust becom e ev ident th a t the basis f o r a m astery o f it is the same. T o one fa m ilia r, f o r instance, w ith the cast go ld in lay an d n o t w ith porce lain , the desire to appreciate an d u n d e r stand f u lly the req u irem en ts th a t porcelain m akes w hich g o ld does n o t im pose suggests itse lf. W ith this th o u g h t in m ind, it m ust be ad m itte d th a t the phys ical requirem en ts o f these m aterials are not the sam e, w h ile the m an ip u lativ e re quirem ents are the same in degree even though n o t in kind. T e c h n ic , in this instance, is m erely the procedure in
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T h e Journal o f the Am erican D ental Association
volved to m anipulate these m aterials to m eet certain requirem ents an d to pro duce definite results in the m o u th ; and,
Fig.
1
.— Cavity on labial surface.
as it is to be p erfec ted in the w o rk in g o f gold, it could be done as easily. T h e difficulty even today is th a t so m any are
Fig. 3.— Cavity on buccal surface.
view ed fro m this an g le, it m ust be ob served th a t either procedure is larg ely and p rim arily a m astery o f details. I t is not to be denied th a t porcelain imposes exacting requirem ents on the operator, but one m ust ad m it the same
not th o ro u g h ly proficient in the m anip ulatio n o f gold, an d can these same m en be expected to do any b etter w ith porcelain? I t seems impossible to an tici pate this in view o f the fa c t th a t the req u irem en t fo r porcelain is more
Fig. 2.— Cavity on labial surface.
Fig. 4.— Cavity on proximal surface.
o f gold. T h e re is a n a tu ra l p referen ce f o r gold as com pared w ith porcelain. W e re it as necessary to m aster porcelain
lim ited . N a tu ra lly , practice leads to p erfectio n , an d i f the o perator is n ot forced to m ake an accurate procedure
V ehe— Porcelain Technic as it Relates to the Inlay
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m ore or less autom atic by a repetition o f it, he w ill n o t succeed unless he has the desire and the persistence to w o rk out a technical perfectio n .
also as regards the n a tu ra l requirem ents o f the m aterials o f w hich the in lay is to be m ade. C av ity p reparation fo r the porcelain in lay does not differ m uch
Fig. J.— Cavity on proximal surface.
Fig. 7.— Cavity on proximo-incisal surface.
O bviously, the object o f the inlay is a restorative one, an d in replacing lost tooth stru ctu re, porcelain meets the added requirem ent o f esthetics. In de signing such a replacem ent o f tooth
fro m th a t f o r a m etal inlay, except in a fe w details, an d these differences are m ade necessary by the physicial req u ire m ents o f porcelain. I n the one su rface cavities, w h eth er
Fig. 6 .— Cavity on proximal surface.
Fig. 8.— Cavity on proximo-incisal surface, labial view.
stru ctu re, several facto rs n a tu ra lly are involved, n o t alone as they p ertain to th a t portion o f the tooth rem ain in g , but
on the labial or the buccal surfaces (F ig s. 1— 3 ) or on proxim al surfaces
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The Journal o f the Am erican D ental Association
o f the a n te rio r teeth (F ig s. 4— 6 ) , the preparation o f the c a v i t y sim ulates closely th a t fo r the m etal inlay. G ood depth is necessary f o r good color and anchorage, an d all w alls should be cut to m eet the surface o f the tooth a t a rig h t angle. T h is precaution should be observed in a ll preparations f o r porce lain , so th a t the porcelain as w ell as the enam el m argins w ill receive all pos sible protection. W h e re the cavity ex tends into the dentin, these w alls m ay be
W h e n separation o f the teeth w ill not provide fo r this, the preparation m ust be m ade w ith this in m in d as w ell. W h e n the incisal or occlusal su rfaces are in volved (F ig s. 7— 1 1 ), the condition at once becomes m ore serious an d com pli cated. H ere, the am o u n t o f the tooth involved, an d the severity an d extent o f the o cclu d in g stresses, very largely govern the preparation. G ood depth w ith sufficient bulk to w ith stan d these stresses is, o f course, im p o rtan t, an d the
Fig. 9.— Cavity on proximo-incisal surface, lingual view.
Fig. 10.— Cavity on proximo-incisal sur face, lingual view.
m ade p arallel, and the base o f the cavity should sim ulate the original contour o f the tooth. T h e cavity outline is gov erned by the am o u n t o f tooth structure th a t is involved, o f course, but the operator should adhere to g rac efu l curves ra th e r th an sharp angles, n o t only fo r esthetic reasons but also because o f the g re a te r ease in adapting the m atrix. A ll w alls should be planed sm oothly, an d the m argins should be sharply de fined. I n proxim al cavities, accessibility fo r m ak in g the m a trix an d fo r setting the w ork m ust be a vital consideration.
m arg in s should n ot be placed directly w here the occluding teeth w ill strike them . M a trix m ak in g n a tu ra lly fo llo w s the cavity p reparation, an d f o r this purpose, p latin u m , gold an d platinous gold foil, in various thicknesses b ut usually o f one one-th o u san d th o f an inch, are used, de p en d in g on the fu sin g point o f the p orcelain an d also on the desire o f the operator. T h is m a trix m ay be m ade in one o f three g en eral w ays: ( 1 ) directly, fo rm in g the m a trix in the tooth cavity; ( 2 ) in d irectly , fo rm in g the m atrix either on the im pression o f the cavity
Vehe— Porcelain Technic as it Relates to the Inlay or on a die o f this cavity; ( 3 ) in directdirectly, fo rm in g the m a trix a t least quite accurately on a die o f the cavity an d th en reburn ish in g it in the tooth cavity. T h e m a trix m ay be m ade in any o f these w ays, depending on the location o f the cavity an d the wishes o f the oper ator. T h e object alw ays is to m ake it en tirely accurate an d to keep it so until the w o rk is com pleted, and how this is done does n o t m a tte r as lo n g as
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beyond the orifice o f the cavity fo r several m illim eters a t least. T h is is necessary so th a t the m a trix w ill not become distorted easily in the fu sin g process a n d to fac ilita te the proper con to u rin g o f the w o rk in bu ild in g . T o shape the m atrix , the m aterial should be placed over the cavity, an d w ith the aid o f sm all pellets o f cotton, spunk or some such m a terial u n d e r a suitable burnisher, it should be w orked into the deeper parts o f the cavity by stretch in g the m e tal b efo re it is fo rced over the surfaces o f the tooth. T h e m etal should be stretched as c a re fu lly an d as
Fig. 12.— Extent o f cervical color worked out. Fig. 1 1.— Cavity on proximoclusal surface. the o p erator does it in th e easiest w ay f o r h im se lf a n d his p atient an d in the shortest tim e. Possibly, th e m ost m atrices are m ade by the d irect m ethod, an d w here there is good access to a cavity on a su rface o f a tooth th a t w ill p erm it the m a trix to be held firm ly d u rin g the b u rnishing proc ess, it is the quickest an d , a t the same tim e, the m ost accurate m ethod. A t least, there is no w ay o f doing it any m ore ac cu rately th a n this. I n burnishing a m a trix directly, it is desirable to have the fo il w ell an n ealed an d o f the proper size. I t should be la rg e enough to project
m uch as possible, an d care should be taken n o t to allo w fo ld s to come into it. L astly , the fo il should be fo rced over the su rface o f the tooth only a f te r the cavity portion has been w orked in a n d th en the m ore accu rate burnishing should be com pleted. F o r this la tte r burnishing, the m a trix should be held rig id ly w ith the aid o f suitable m ate rial such as C h in a silk cu t in to strips, o r some sort o f tape o f silk o r cotton, o r even rubber dam . P erhaps o f these m aterials com m on silk seam binding th a t m ay be obtained a t the notion coun te r o f any dry goods store is as suitable as an y th in g . A t this point, it is g enerally w ell to an n eal the fo il in the flame o f
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T h e Journal o f the A m erican D ental Association
a blow pipe, a f te r w hich the final burn ish in g is done. A last inspection should show an en tirely accurate re p roduction of. the cavity in every detail. T h e r e should be no folds no r tears at the cavity m argins an d it should have a sm oothness corresponding to th a t o f the cavity an d tooth surface. Sticky w ax th a t w ill b u rn off cleanly m ay be used to fac ilita te the rem oval o f the m a trix w ith o u t distortion. A m a trix m ay be m ade in d irectly either over an im pression o f a cavity or on a die o f the cavity. T h e r e is a
the cavity portion upperm ost, a f te r w hich the m a trix is m ade in the usual w ay. T h e difficulties th a t m ay be en countered in this process are tears at the m arg in s ju st w here they m ust not be. T h is can be avoided by c a re fu lly tu ck in g the fo il into the deeper por tions even w ith the fo ld s b efo re sw aging it dow n to place. I n this m a trix , fo ld s do n o t m a tte r, an d the req u irem en t is th a t the inside o f the m a trix correspond in sm oothness w ith th a t o f the cavity. T h e technic fo r m ak in g a m a trix ind irectly is w ell k now n an d need n ot
Fig. 13.— Outline of incisal color.
Fig. 14.— Completed color diagram.
d istinct advantage in m aking it over an im pression o f a cavity in the class o f cavities w ith fo u r w alls, such as the labial, buccal an d some proxim al cav ities; fo r, in d oing so, the inside o f the m a trix corresponds to the cavity size an d outline ra th e r th an to the outside o f it, a n d the thickness o f the foil has n o th in g to do w ith the fit o f the com p leted inlay. T h e technic fo r this p ro cedure is m in u tely exacting but not difficult. T h e im pression o f the cavity m ay be obtained in a good cem ent, and the m a trix is then m ade thereon. T h e best procedure consists in m ak in g the im pression in casting w ax an d casting this im pression in gold. T h is casting is th en m ounted in a sw aging base w ith
be considered here. I t corresponds to the d irect m ethod except th a t because the m a trix is m ade out o f the m o u th , it is m ore easily and quickly done. T h e in d ire ct-d irec t m ethod is in d icated in the m ore difficult cases in w hich the operator wishes to fo rm the m a trix m ore or less accu rately on a die m ade o f ce m en t, usually, an d th en reburnish it in the tooth cavity. T h e color problem should be care fu lly taken up a t the com pletion o f the m atrix , or the im pression o f the cavity i f the m a trix is to be m ade in d irectly . N o m a tte r how accurate the inlay may be w hen com pleted, if the color is w ro n g or i f it violates the esthetic fe a tu re in this respect, it m ust be co n
Vehe— Porcelain Technic as it Relates to the Inlay sidered a fa ilu re . Because color m eans so m uch in the inlay, it is necessary th a t it receive c a re fu l consideration. T h e principle o f color in terp retatio n in porcelain is the same in the inlay th a t it is in the veneer crow n except th a t we are d ea lin g w ith but a p a rt o f a tooth cro w n an d w e have reflection and re fra ctio n o f lig h t to deal w ith to a g rea ter extent. H o w ev er elusive this problem m ay appear to be to the b e g in ner, it should nev er be m ysterious, fo r the color problem can be w orked out to be as scientific and as accurate as any
Fig. 15.— Cross-section of color scheme. p art o f the procedure. T h e first req uisite is a color guide th a t accurately represents the colors o f the porcelain w ith w hich w e are w o rking. T h is m eans th a t the m a n u fa c tu re r’s color guide m ay n o t be rig h t. W ith this, th en , as a beg in n in g , w e m ust le arn to see the colors in the tooth as they really are an d th en m atch them w ith the colors on the color guide. I t is best to diagram the color requirem ents o f each case on a suitable card. T h is d iagram may consist o f a sketch o f the labial or buccal o utline o f the tooth to be treated , w ith the ex tent o f the involvem ent an d the color requirem ents accurately w orked out. (F ig s. 12— 1 5 .) Such a record has m any advantages an d m ay include,
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aside fro m this color d iag ram , m easure m ents to assist in b u ild in g the w ork, stain in g in fo rm a tio n an d any o th e r data th a t m ay be o f help. W h e n a preparation is properly m ade, a n d an accurate m a trix obtained, an d the color req u irem en ts are exactingly w orked out an d recorded, the b u ild in g o f the inlay should n o t be difficult. N a tu ra lly , g re a t care m ust be exercised constantly n o t to d isto rt the m atrix d u rin g the process o f b u ild in g th e w ork. Provision m ust also be m ade to prev en t distortion d u rin g the fu sin g o f the
Fig. 16.— Color requirements for the inlay. porcelain. T h e la tte r effect can be pre vented by investing the m a trix , o r as is usually done, by p ain tin g a th in solution o f shellac in alcohol on the w alls f a r thest fro m the cen ter o f the m a trix or a t the points w here the m ost severe con trac tio n w ill take place. O th e r m ethods are used to obviate this possibility, such as c u ttin g the porcelain a f te r it is bu ilt w ith a sharp lance in th e fo rm o f the le tte r X or b u ild in g the porcelain to f u ll co n to u r w ith o u t covering the w alls o f the m a trix . I t seems th a t the shellac m ethod is the accepted one because it allow s f u ll co n to u rin g a t each b u ild in g an d it likew ise is the m ore positive. T h e shellac is only applied b efo re the first contouring.
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T h e Journal o f the A m erican D ental Association
I n w o rk in g the porcelain, care should be taken to w o rk out all air an d to keep it clean. A ng les an d grooves m ust be em phasized an d an am o u n t m ay be a llo w ed f o r contraction in fu sin g , but aside fro m this, the w o rk should not be o vercontoured, n o r should porcelain be b u ilt over the m a rg in o f the fo il. T h e cervical an d incisal colors should be properly placed f o r co rrect color effects a t each contouring. U sually, three fu s ings are sufficient to com plete an inlay an d overbiscuiting or o v erfu sin g g en era lly are fa ta l to a good result. Ju st b efo re the last conto u rin g , the inlay m ay be tried in the m o u th to v erify co ntour, contact an d occlusion in the m ore difficult cases, a n d it is also best to dress dow n the m a rg in o f the foil w h ile it is in th e tooth o r in the m etal die w ith suitable sm all tru e ru n n in g stones. T h is dressing dow n is n o t done q uite so f a r w h en m ak in g the m a trix on a n impression. A f te r this fin al fu sin g , the fo il is rem oved an d the cavity su rface o f the inlay should be roughened to obtain g re a te r adhesion o f the cem ent. T h is m ay be done w ith a suitable stone or d iam ond disc, o r w ith hydrofluoric acid. T h e w o rk should be c a re fu lly set; otherw ise, a p e rfe c t restoration m ay be ru in ed in a m o m en t by fra c tu rin g a m a rg in . T h e selection o f a proper ce m e n tin g m edium m ay be som ew hat o f a problem , since the silicates have come to supplant, at least partly, the use o f the oxyphosphate cem ents fo r this purpose. As the silicates have not am ple tim e to dem onstrate th e ir com plete reliability f o r the cem entation o f this w ork, i f one is perm itted to ju d g e th e ir usefulness g enerally, one can n o t rest w ith com plete assurance in
th e ir use. I t is hoped th a t the n ew er cem en tin g m edium s w ill live up to our expectations o f th em , as the color ad vantage in the porcelain a f te r place m e n t is so m uch superior to w h a t we have had to contend w ith th a t the operator has every opportunity to be com e enthusiastic. I n cem en tin g w ith w h atev er m edium , the w o rk should be held in place firm ly u n til the cem ent has become set quite w ell o r u n til there is little d an g e r o f the in lay being moved. I t is n ot de sirable to rem ove all o f the cem en t at this tim e, b ut at a fu tu re sittin g , the m a rg in should be finally com pleted by ru n n in g over th em w ith a suitable sm all A rkansas stone u n d er w ate r, an d the occlusion should be checked again. T h is , th en , com pletes the operation, and w h eth e r it is a sim ple one su rface restoration or one th a t is m ore com pli cated, it m ust be p lainly evident th a t the procedure is larg ely m ade up o f care f u lly w ork ed o ut details. P erhaps m any o f us in attem p tin g such an operation have the w hole mass o f detail in m in d , w ith m ore or less confusion to o u r selves w h en w e should be confined to but one an d allo w the next one to come in n atu ra lly . I t is b ut logical to reason th a t each step should be c a re fu lly co m pleted in the procedure b efo re the suc ceeding one is attem p ted , fo r a good result, an d w hen one fo llo w s th ro u g h an operation in this m a n n er, there can be b u t one resu lt; nam ely, a restoration th a t is the highest expression o f the re storative a rt, an d i f it has been properly selected, it w ill be a source o f satisfac tion to the operator and o f gratificatio n to the patient.
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