A R T IC L E S
The preformed stainless steel crown for restoration of permanent posterior teeth in special cases Theodore P . CroII, D D S C. R . Castaldi, D D S , M S D , F a r m in g to n , C o n n
T h e r e a r e p ro b lem s involving p e r m a n e n t p o ste rio r teeth f o r w hich the stainless s te e l crow n m a y p ro v id e the m ost d e s ira b le short-term solution. In p la c in g the crow n, em p h a sis sh o u ld b e g iv en to reco gn itio n o f th e w id e variation o f a v a ila b le crow ns, o cclu sa l con sid era tio n s, the im p o rta n ce o f the r u b b e r dam , a n d the u s e o f a p re c em en ta tio n ra d io g ra p h to co n firm m a rg in adaptation o f the crow n.
of a posterior tooth for w h ich a p in retain ed alloy restoration is co n train d icated becau se of pu lpal con siderations; □ as a sem iperm anent, m ainte n an ce restoration until a cast gold or porcelain-fused -to-gold restoration is fin a n cia lly feasible for the patient; □ for fu ll coverage on young post erior teeth that have enam el or d en ti nal abnorm alities; □ for restoration of a tooth during end od on tic treatm ent in w hich ac cess is m ade through the occlu sal surface of th e steel crown. The objectives sought in the use of the stainless steel crow n procedure are id en tical to those of any restora tive dental treatm ent. Not only m ust the o cclu sion be recreated id eally for the patien t but, in ad dition, proxim al contact, where indicated , m ust also be established. The overall tooth architecture m ust be restored to be physiologi ca lly accep tab le and to preserve m as ticatory fu n ction and periodontal in tegrity. T Y P E S O F ST A IN L E SS ST E EL CRO W N S.
Q
k - J i n c e the late 1940s w hen it was first introduced into pedodontics, the chrom e steel crow n has gradually becom e a reliable, econom ical, and tech n ica lly reasonable restoration. H um phrey’s 1 d escription of the chrom e steel crow n in 1950 suggested techniqu es for im plem en tation of the restoration for d ecidu ous teeth. In the literature are listed many m odifications of the techniqu e in the areas of in d icatio n s,2'9 preparation of the to oth,3‘5-7-9‘ 13 preparation and ad aptation of the preform ed crow n,3, 710,12 and, m ore recently, gingival response to th e finished restora tio n .3,6'14 C om m ercially available crow ns have also changed through the years in regard to the working properties of the m etal, crown anatom y, prefestoohing, and p re crim ping of the crown. M ost reports in the literature are 644 ■ JADA, Vol. 97, October 1978
confined to the use of the stainless steel crow n restoration for deciduous teeth. Only b rief and sporadic refer en ces are made to the potential of the crow n for certain un ique problem s found in perm anent teeth .3,8,9,13,15 A detailed d escription for fabricat ing a preform ed stainless steel crown restoration for a perm anent posterior tooth is given. Em phasis is on occlu sal considerations, ideal adap tation, and an optim um field of oper ation.
I n d ic a tio n s T h e use of a preform ed stainless steel crow n restoration is indicated: □ w ith extensive carious destruc tion of a posterior tooth in w hich caries control is indicated, but reten tion of the tem porary fillin g material is uncertain; □ w ith gross carious destruction
S tain less steel crow ns are avail able com m ercially in num erous form s by several m anufacturers. Som e are prefestooned, som e are precrim ped and prefestooned, and others have no special fin ish around the gingival m argin. Cusp heights and cusp angulations vary depend ing on the m anufacturer. A ll the crow ns, how ever, rely on the skill of the operator for suitable adaptation to the prepared tooth. M ost crow ns are acceptable, but sk illfu l hand ling of the crow n after preparation of the tooth is the key to success. C ircum stances in w hich any of the prefestooned and precrim ped crow ns need only m inim al m o d ifica tions are rare.
P ro c e d u re T h e procedure consists of rad iologi cal consid erations, ad m inistration of the an esth etic, occlu sal con sid erations before preparation of the tooth, preparation of the operative field , preparation of the tooth and
A R T IC L E S
Fig 1 ■ Left, overeruption of opposing m olar is evident; middle, areas to be reduced are outlined; right, overeruption is corrected by selective tooth reduction.
protection of the pulp, selectio n and adaptation of the crow n, establishing occlu sal relatio n sh ip s, radiograph ic confirm ation o f gingival fit, and cem entation of the crown. RADIOLOGICAL
CONSIDERATIONS.
A long w ith a preoperative diagnostic radiograph of the affected tooth and associated structures, precem enta tion radiographs are essential to as sure precise m arginal adaptation of the crow n by show ing interproxim al areas w here m arginal coverage is dif ficu lt to assess. ANESTHESIA. As a prim ary concern
of the dental practitioner is com plete com fort of the p atien t during dental treatm ent, routine local adm inistra tion of an an esth etic is essential to elim inate pain from the cutting pro cedures and from the retraction and m anipulation of the soft tissues as sociated w ith the treatm ent.
pie of how occlu sal relationships have b een in flu en ced . T h e opposing m olar has overerupted into the m an dibular first m olar space. It was n ec essary first to correct the overerup tion by tooth red uction (Fig 1 m iddle, right). T h e occlu sal adjustm ent should be done at th is stage to estab lish the correct occlu sal plane in i tially. In the case in Figure 1, a great deal of occlu sa l red uction of the op posing second m olar was necessary.
cem entation radiograph (Fig 2). In m ost cases, tw o types of rubber dam clam ps are used. T h e first is a retentive clam p to secu re the dam in position; it is usu ally p laced on a tooth d istal to the tooth being re stored. T h e secon d is a retracting clam p, w h ich is d esigned to gently d isplace the free gingiva on the tooth that is being restored.
PREPARATION OF THE OPERATIVE FIELD. W ith the excep tion of ch eck
m ust be on all factors concerning preparation of the tooth to be restored w ith a stainless steel crow n. Ease of adaptation of the crow n and success of the procedure have their found a tions in a properly prepared tooth. There are various com binations of instrum ents that can be used effec tively for preparation of th e tooth. One of us (TPC) prefers a snub-nosed barrel diam ond at h ig h speed for gross red uction and eith er a flam e-
ing occlu sa l relationsh ip s ju st before cem entation , th e entire procedure should be done w ith use of the rubber dam. T h e m ajor advantage of the rubber dam is that gingival m arginal fit can be v isu alized around the en tire circu m feren ce of the tooth being restored w ith the possible exception of the cen ter of the proxim al surfaces, w hich can be evaluated with a pre
PREPARATION OF TOOTH AND PRO TECTION OF PULP. M ajor em phasis
OCCLUSAL CONSIDERATIONS BE FORE PREPARATION OF THE TOOTH.
A lthough the im portance of studying occlu sal relatio n sh ip s before actual cutting procedures begin is em phasized in restorative dentistry, these occlu sal relationsh ip s in the young patient are often ignored be cause o f the dynam ic physiology of the m ixed and early perm anent den titions. How ever, if the perm anent tooth to be restored w ith a steel crow n is grossly carious, occlusal re lationship s m ay be adversely af fected and m ay require adjustm ents before preparing the tooth to be re stored. Figure 1 left is a good exam-
Fig 2 ■ Precem entation radiograph confirm s proxim al m arginal integrity of crown.
C roll-C astaldi : PREFORMED STA IN LESS STEEL CROWNS ■ 645
A R T IC L E S
Fig 3 ■ Rounding angles dur ing preparation. If areas a and b rem ain sharp, crown seating may be hindered. Crown sits well when these areas are rounded.
no gross cervical bulges on perm a nent teeth that facilitate retention of the crow n. Cusp heights are m uch greater in perm anent teeth. A lso, conservation of tooth structure is m ore cru cial for teeth of the perm a nent dentition, as in all probability, a cast gold restoration w ill be in d i cated, w hich m ust not have its reten tion com prom ised during a previous procedure. A n essential step in preparation of the tooth is rounding of all angles. T his inclu d es all axio-occlu sal line angles as w ell as occlu so bu ccal, occlu solin g u al, and occlusoproxim al. Crown seating and accu rate
tapered diam ond or a 169 long car bid e bur for proxim al and m arginal preparation; the other one of us (CRC) frequently uses diam ond disks and stones w ith the straight handpiece at slow speed. Liberal water spray is essential during preparation to elim inate u n pleasant odors, reduce dust from tooth debris, and, m ost im portantly, to lim it iatrogenic therm al injury to vital pulp tissu e s.16 There are anatom ical variations and p ractical considerations that alter the rationale of the preparation for a perm anent tooth com pared with that of a deciduous tooth. There are
Fig 4 ■ Procedure for placing stainless steel crow ns
for
perm anent
posterior
teeth.
A,
occlusal reduction is outlined. B, occlusal and proxim al reduction is completed and pulp pro tection procedures are performed. C, crown was shortened at gingival m argin. Notice how retrac tion of gingival tissue by rubber dam clamp shows open gingival m argins that a re to be recrim ped and recountered. D, additional crim p ing and contouring im prove fit and only sm all buccal area requires more m arginal adaptation. E, w ith rubber dam removed, occlusion m ay be evaluated in all functional movements.
646 ■ JADA, Vol. 97, October 1978
m arginal adaptation are facilitated by this operation4 (Fig 3). Figure 4 show s the procedure for p lacing the steel crown. In itially, the tooth is reduced occlu sally in a sim i lar m anner to the reduction for a cast gold crow n. The general anatom ical form of the crown in reduced d im en sio n s should be m aintained w h ile as suring betw een 1 and 2 m m occlu sal clearan ce in the entire envelope of excu rsive m ovem ents. T h is is achieved readily w ith the barrelshaped diam ond. T he occlu sal re duction is achieved first to facilitate better control and vision for the next step, w hich is the proxim al red u c tion. T h e proxim al slices elim inate all con tact w ith ad jacent teeth and create the space required to adapt the crow n and to restore contact if in d i cated. Proxim al preparation is achieved w ith the flam e-tapered diam ond, or the 169 long carbide bur. It is helpful to place a w ooden wedge or flattened round toothpick betw een
A R T IC L E S
the teeth to prevent in terference of the rubber dam and to avoid lacera tion of the gingiva. T h e next step is to slig htly reduce the convexity of the bu ccal and lin g ual surfaces of the tooth. It is im por tant to reduce these surface con vexities in the gingival third of the tooth so the stainless steel crow n may assum e the original convexity and thus preclud e an overcontoured, en larged b u ccolin gu al dim ension. A fin e, feather-edged gingival m argin at the crest of the gingiva should be produced, w hich w ill be covered by the thinned sm ooth edge of the crow n. W hen caries extends subgingivally, the m argin m ust ex tend subgingivally also to furnish fu ll coverage of the preparation after com plete caries rem oval. T h e edge of the crow n m ust be designed to em brace secu rely the m argin around the entire periphery of the tooth. Caries rem oval is achieved in the conventional m anner w ith spoon ex cavators and slow -speed round burs. Pulpal insulation procedures (bases and varnish application) are now performed. SELECTION AND ADAPTATION OF CROWN. N one of the available com
m ercial crow ns are suitable for every situation. In fact, clin icia n s who are concerned about good occlu sal rela tionship s in restorative dentistry m ay be disappointed w ith the types of crow ns on the m arket. O cclusal m orphology, cusp height, b u cco lin gual w idth, and occlusogingival length vary w idely. Se le ctio n of a sp ecific brand of crow n may becom e easier by having a set of study m odels as part of the p atien t’s perm anent record. Som e prefestooned crow ns are too short occlu so g ingivally in cases in w hich there is deep proxim al caries. M ink and H ill17 described how this defect can be overcom e for the deciduous tooth by spot w elding an additional p iece of crow n or band m aterial. For perm anent teeth, having at least one of the nonfestooned crow ns available is recom m ended rather than restor ing to M in k ’s add-on procedure. The cusp heights of som e types of crow ns tend to be steep and m ore like
new ly erupted molars. T h e occlusal m orphology of other types resem bles older, m ore worn teeth. E con om ic consid erations in office prac tice m ay preclud e having a fu ll sel e ctio n o f all five available brands of crow ns. N evertheless, the wide variation in occlu sal anatom y of teeth necessitates having at least two brands available. O nce a suitable brand has been chosen, there are several ways to select a sp ecific size crow n for a tooth. Som e p ractitioners5,13 advo cate m aking m easurem ents of the prepared tooth, w hereas others use the trial-and-error m ethod. We tend to agree with A lle n 10 in h is observa tion that consid eration of the contra lateral tooth, if possible, com bined w ith trial-and-error is the m ost expe dient m eans of crow n selectio n after exp erien ce is gained w ith the te ch nique. T h e aim is to select a pre form ed crow n that fits snugly over the preparation, that w ill assure rees tablishm ent of proxim al contact, and that w ill perm it the m arginal areas to be crim ped and contoured to assure a tight, ideal, m arginal adaptation. At this p oint in the procedure, the use of the rubber dam is extrem ely im portant. D in er18 recognized the d esirability of observing directly the m arginal areas of the crow n during adaptation. V isualization of every m arginal area is im portant for ideal adaptation and proper use of the rub ber dam; the clam p as a retractor can provide this visib ility . A heavy dam, w ith sm all hole size, aids in retract ing the m arginal gingiva in co n ju n c tion w ith a retraction clam p. T h e interproxim al part of the rubber dam and suitable w edging retracts th e in-
terproxim al gingiva. Proper length of the stainless steel crow n has already been described and may be achieved w ith curved crow n and bridge scissors follow ed by refinem ent w ith a greenstone. Castaldi3 has show n that a com m on error in fabricating a preformed crow n for deciduous teeth is to m ake the crow n too short on proxim al sur faces, predisposing that surface to caries. T his area is norm ally covered by the gingival papilla, but is easily view ed w ith rubber dam retraction of the tissu e (Fig 4C). In adapting the crow n, the original length of the c lin ica l crow n should be recreated. Im portant also is the orientation of the crow n so it reestab lish es the original long axis of the crow n to the tooth,3 w hich w ill be help ful in elim inatin g interfering cusps, and associated m andibular shifts. A fter achievin g proper orientation of the crow n on the tooth, the mar ginal areas are critica lly exam ined. O nly the areas im m ediately below the proxim al contacts cannot be eas ily seen (Fig 4C, 4D). A pair of crow n-crim ping pliers is used to crim p the m argin of the crow n (Fig 5 left). T h ese pliers scal lop the periphery, w h ich is then sm oothed w ith a pair of contouring p liers (Fig 5 right). T h e crim ped crow n is again seated on the tooth and the m argins are reexam ined v i sually and with the explorer. Any open area d isclosed by th is exam ina tion can be marked w ith an ind elible, fine-pointed pen cil or felt-tip marker to ind icate where additional crim p ing and contouring may be n eces sary.
Fig 5 ■ Use of pliers for shaping margins. Left, crimping pliers crimp gingival margin but leave scalloped edge. Right, contouring pliers are used to smooth and contour scalloped margins. C roll-C astaldi : PREFORMED STAIN LESS STEEL CROWNS ■ 647
A R T IC L E S
Fig 6 ■ Establishing correct occlusal relationships. Left, pencil lines indicate prem ature contact of crown. Right, pencil lines indicate that crow n has been seated completely.
W hen ideal adaptation has been achieved, the rubber dam is removed. T h e crow n is reseated and occlu sion is evaluated (Fig 4E). T h e use of a wooden tongue blade split lengthw ise serves as an excellen t bite stick for applying force in a particu lar area w h ile seating the crown. Prem aturities, coronal orientation, length of the crow n, and stability of the restoration are all verified and de ficie n cies are corrected. ESTABLISHING
OCCLUSAL
RELA
TIONSHIPS. T h e patient should not
be left w ith an open bite relationship from a high crow n. To assure that the crow n is not high, it is rem oved and the patient is instructed to close the m outh to fu ll occlusion. A pencil m ark is m ade to record the overbite relationsh ip in the canine area (Fig 6). The crow n is then replaced and the correct relationsh ip is confirm ed. RADIOGRAPHIC CONFIRMATION OF THE GINGIVAL FIT. Before cem enta
tion, a bite-w ing radiograph is taken to verify proxim al m arginal integrity. T h is step is a cru cial one, as seen in Figure 2. If the crow n is too long, there is still an opportunity to reduce the length. If it is too short, the add-on procedure or adaptation of another crow n is indicated. FINAL FINISHING AND CEMENTA TION. After all occlusal and gingival
adjustm ents have been accom plished , it m ay be necessary to re 648 ■ JADA, Vol. 97, October 1978
crim p the crow n as the m etal may expand m inutely each tim e the crow n is seated and rem oved. The m argins of the crow n are then refined and sm oothed w ith a greenstone and a large rubber w heel that rem oves all scratches. F inal treatm ent of the m argin can be accom plished readily by buffing w ith a rag w heel and tripoli abrasive and then polishing w ith jew eler’s rouge. It is most im portant to thoroughly clean the interior of the crow n with a w et cotton swab or sm all brush b e fore cem entation. Three types o f cem ent w idely used for cem entation of the stainless steel crow n are zin c oxyphosphate, polycarboxylate, and zin c oxide and eugenol. After suitable pulp treat m ent, any of these cem ents are ac ceptable. T h e rubber dam is replaced and the tooth is cleaned and dried w ith a lib eral water spray and gentle ap p lica tion of warm air. A cream y m ixture of cem ent is prepared and the crow n is then filled about three quarters full, m aking sure that all m argins are cov ered. It is then seated on the tooth w ith gentle finger pressure or w ith a tongue blade and m ild biting force. E xcess cem ent is expressed around the m argins. T he rubber dam is now removed; the interproxim al rubber is snipped w ith a pair of scissors. T h e previ ously established occlu sal relation ships and the crow n orientation on the prepared tooth can now be ver
ified. D eviations can be corrected be fore the cem ent hardens. R ecreation of cen tric o cclu sion is confirm ed w ith use of a pen cil lin e on the an terior teeth. T h e cem ent is allow ed to set for several m inutes w h ile the p a tien t bites gently on a 2-in square gauze sponge. T reatm ent of the surrounding soft tissu e is im portant both during and after th e procedure. An id eally adapted crow n, w ith sm ooth and polished m argins, rep licatin g the hard tissu e architecture w h ich once existed , is param ount for potentiat ing optim al gingival health (w ritten com m un ication, E. B. Brooks, A pril 1 9 7 7 ).14 Rem oval of excess cem ent is im portant to prevent gingival irrita tion.
L o n g e v ity o f s ta in le s s steel c ro w n fo r p e rm a n e n t te e th T he m ajor factors concerning the longevity of the crow n are gingival recession, recurrent m arginal caries, dissolution o f the cem ent, and w ear ing through on the occlu sal surface of the crown. T h e only report of the long-term potential of the stainless steel crow n for perm anent teeth is by K im m elman and R ie sn e r.15 T hey review ed 65 restorations of w h ich 13 had b een in the m outh from 4 9 to m ore than 120 m onths. No description of clin ical techniqu e is inclu d ed in th eir obser vations. O ne steel crow n was observed by
A R T IC L E S
one of us (TPC) in 1973 in the m outh of a 42-year-old A m erican soldier. T h e restoration had been placed on a m axillary m olar in 1 9 5 8 , according to the m ilitary dental records. No signs of gingival inflam m ation were evident, and although w ear facets existed on the occlusal surface, none of them was worn through the m etal. A sm all area of recession of the palatal gingiva was evident, expos ing about 1 mm of root surface; how ever, the crow n m argin was w ell adapted in that area. It was unfortu nate that the contralateral m olar was absent, so that the tooth w as unable to be view ed for palatal recession in an analagous area. T h e patient re ported no sym ptom s during the en tire 1 5-year history of the restoration. We do not recom m end the use of the preform ed stainless steel crow n for perm anent teeth as a substitute for the p recision cast restoration. Rather, it is our intention to ou tline certain unique situations in w hich the pre form ed crow n, w hen carefu lly done, can be a respectable interim restora tion until a more desirable fu ll cast crow n is possible.
1. Humphrey, W.P. Uses of chrome steel in children’s dentistry. Dent Survey 26:945 July 1950. 2. Braff, M.H. A comparison between stain less steel crowns and multisurface amalgams in primary molars. J Dent Child 42:474 NovDee 1975.
3. Castaldi, C.R. Operative dentistry. In Goldman, H.M., and others (eds.J. Current therapy in dentistry. St. Louis, C. V. Mosby, 1966, vol 2, pp 621-655. 4. Finn, S.B . C linical pedodontics, ed 3. Philadelphia, W. B. Saunders, 1967, pp 184186. 5. Full, C.A.; Walker, J.D.; and Pinkham, J.R. Stainless steel crowns for deciduous molars. JADA 89:3 6 0 Aug 1974. 6. Henderson, H.Z. Evaluation of the pre formed stainless steel crown. J Dent Child 40:353 Sept-O ct 1973. 7. McDonald, R.E. Dentistry for the child and adolescent, ed 2. St. Louis, C. V. Mosby, 1974, pp 206-209. 8. Rapp, R. A sim plified yet precise technic for the placem ent of stainless steel crowns on primary teeth. J Dent Child 33:101 March 1966. 9. Troutman, D.C. Chrome steel crowns: a sim plified self-assessm ent technique. J Acad Gen Dent 24:28 May-June 1976. 10. Allen, K.R. Restoration of the extensively carious primary molar. Aust Dent J 16:8 Feb 1971.
11; Helm, H.W. Sim plified procedure for stainless steel crowns in paedodontics. J Can Dent Assoc 29:369 June 1963. 12. Law, D.B.; Lewis, T.M .; and Davis, J.M. An atlas of pedodontics. Philadelphia, W. B. Saunders, 1969, pp 181-186. 13. Mink, J.R., and Bennett, I.C. The stainless steel crown. J Dent Child 35:186 May 1968. 14. Webber, D.L. Gingival health following placem ent of stainless steel crowns. J Dent Child 41:186 May-June 1974. 15. Kimmelman, B .B ., and Riesner, A.L. Soft stainless steel crown as an interm ediate restora tion: observations in clinical practice. Gen Dent 25:21 July-Aug 1977. 16. Langeland, K. Biologic considerations in operative dentistry. Dent Clin North Am 125:131 March 1967. 17. Mink, J.R., and H ill, C.J. M odification of the stainless steel crown for primary teeth. J Dent Child 38:197 May-June 1971. 18. Diner, H. An improved technique for gingival adaptation of the stainless steel crown. J Dent Child 33:266 July 1966.
THE AUTHORS
Dr. Croll is a resident in pediatric den tistry and Dr. Castaldi is chairman of the department of pediatric dentistry at the University of Connecticut Health Cen ter, Farmington, 06032. Address re quests for reprints to Dr. Castaldi.
CROLL
CASTALDI
C roll-C astaldi : PREFORMED STA IN LESS STEEL CROWNS ■ 649
The preformed stainless steel crown for restoration of permanent posterior teeth in special cases Theodore P . CroII, D D S C. R . Castaldi, D D S , M S D , F a r m in g to n , C o n n
T h e r e a r e p ro b lem s involving p e r m a n e n t p o ste rio r teeth f o r w hich the stainless s te e l crow n m a y p ro v id e the m ost d e s ira b le short-term solution. In p la c in g the crow n, em p h a sis sh o u ld b e g iv en to reco gn itio n o f th e w id e variation o f a v a ila b le crow ns, o cclu sa l con sid era tio n s, the im p o rta n ce o f the r u b b e r dam , a n d the u s e o f a p re c em en ta tio n ra d io g ra p h to co n firm m a rg in adaptation o f the crow n.
of a posterior tooth for w h ich a p in retain ed alloy restoration is co n train d icated becau se of pu lpal con siderations; □ as a sem iperm anent, m ainte n an ce restoration until a cast gold or porcelain-fused -to-gold restoration is fin a n cia lly feasible for the patient; □ for fu ll coverage on young post erior teeth that have enam el or d en ti nal abnorm alities; □ for restoration of a tooth during end od on tic treatm ent in w hich ac cess is m ade through the occlu sal surface of th e steel crown. The objectives sought in the use of the stainless steel crow n procedure are id en tical to those of any restora tive dental treatm ent. Not only m ust the o cclu sion be recreated id eally for the patien t but, in ad dition, proxim al contact, where indicated , m ust also be established. The overall tooth architecture m ust be restored to be physiologi ca lly accep tab le and to preserve m as ticatory fu n ction and periodontal in tegrity. T Y P E S O F ST A IN L E SS ST E EL CRO W N S.
Q
k - J i n c e the late 1940s w hen it was first introduced into pedodontics, the chrom e steel crow n has gradually becom e a reliable, econom ical, and tech n ica lly reasonable restoration. H um phrey’s 1 d escription of the chrom e steel crow n in 1950 suggested techniqu es for im plem en tation of the restoration for d ecidu ous teeth. In the literature are listed many m odifications of the techniqu e in the areas of in d icatio n s,2'9 preparation of the to oth,3‘5-7-9‘ 13 preparation and ad aptation of the preform ed crow n,3, 710,12 and, m ore recently, gingival response to th e finished restora tio n .3,6'14 C om m ercially available crow ns have also changed through the years in regard to the working properties of the m etal, crown anatom y, prefestoohing, and p re crim ping of the crown. M ost reports in the literature are 644 ■ JADA, Vol. 97, October 1978
confined to the use of the stainless steel crow n restoration for deciduous teeth. Only b rief and sporadic refer en ces are made to the potential of the crow n for certain un ique problem s found in perm anent teeth .3,8,9,13,15 A detailed d escription for fabricat ing a preform ed stainless steel crown restoration for a perm anent posterior tooth is given. Em phasis is on occlu sal considerations, ideal adap tation, and an optim um field of oper ation.
I n d ic a tio n s T h e use of a preform ed stainless steel crow n restoration is indicated: □ w ith extensive carious destruc tion of a posterior tooth in w hich caries control is indicated, but reten tion of the tem porary fillin g material is uncertain; □ w ith gross carious destruction
S tain less steel crow ns are avail able com m ercially in num erous form s by several m anufacturers. Som e are prefestooned, som e are precrim ped and prefestooned, and others have no special fin ish around the gingival m argin. Cusp heights and cusp angulations vary depend ing on the m anufacturer. A ll the crow ns, how ever, rely on the skill of the operator for suitable adaptation to the prepared tooth. M ost crow ns are acceptable, but sk illfu l hand ling of the crow n after preparation of the tooth is the key to success. C ircum stances in w hich any of the prefestooned and precrim ped crow ns need only m inim al m o d ifica tions are rare.
P ro c e d u re T h e procedure consists of rad iologi cal consid erations, ad m inistration of the an esth etic, occlu sal con sid erations before preparation of the tooth, preparation of the operative field , preparation of the tooth and
A R T IC L E S
Fig 1 ■ Left, overeruption of opposing m olar is evident; middle, areas to be reduced are outlined; right, overeruption is corrected by selective tooth reduction.
protection of the pulp, selectio n and adaptation of the crow n, establishing occlu sal relatio n sh ip s, radiograph ic confirm ation o f gingival fit, and cem entation of the crown. RADIOLOGICAL
CONSIDERATIONS.
A long w ith a preoperative diagnostic radiograph of the affected tooth and associated structures, precem enta tion radiographs are essential to as sure precise m arginal adaptation of the crow n by show ing interproxim al areas w here m arginal coverage is dif ficu lt to assess. ANESTHESIA. As a prim ary concern
of the dental practitioner is com plete com fort of the p atien t during dental treatm ent, routine local adm inistra tion of an an esth etic is essential to elim inate pain from the cutting pro cedures and from the retraction and m anipulation of the soft tissues as sociated w ith the treatm ent.
pie of how occlu sal relationships have b een in flu en ced . T h e opposing m olar has overerupted into the m an dibular first m olar space. It was n ec essary first to correct the overerup tion by tooth red uction (Fig 1 m iddle, right). T h e occlu sal adjustm ent should be done at th is stage to estab lish the correct occlu sal plane in i tially. In the case in Figure 1, a great deal of occlu sa l red uction of the op posing second m olar was necessary.
cem entation radiograph (Fig 2). In m ost cases, tw o types of rubber dam clam ps are used. T h e first is a retentive clam p to secu re the dam in position; it is usu ally p laced on a tooth d istal to the tooth being re stored. T h e secon d is a retracting clam p, w h ich is d esigned to gently d isplace the free gingiva on the tooth that is being restored.
PREPARATION OF THE OPERATIVE FIELD. W ith the excep tion of ch eck
m ust be on all factors concerning preparation of the tooth to be restored w ith a stainless steel crow n. Ease of adaptation of the crow n and success of the procedure have their found a tions in a properly prepared tooth. There are various com binations of instrum ents that can be used effec tively for preparation of th e tooth. One of us (TPC) prefers a snub-nosed barrel diam ond at h ig h speed for gross red uction and eith er a flam e-
ing occlu sa l relationsh ip s ju st before cem entation , th e entire procedure should be done w ith use of the rubber dam. T h e m ajor advantage of the rubber dam is that gingival m arginal fit can be v isu alized around the en tire circu m feren ce of the tooth being restored w ith the possible exception of the cen ter of the proxim al surfaces, w hich can be evaluated with a pre
PREPARATION OF TOOTH AND PRO TECTION OF PULP. M ajor em phasis
OCCLUSAL CONSIDERATIONS BE FORE PREPARATION OF THE TOOTH.
A lthough the im portance of studying occlu sal relatio n sh ip s before actual cutting procedures begin is em phasized in restorative dentistry, these occlu sal relationsh ip s in the young patient are often ignored be cause o f the dynam ic physiology of the m ixed and early perm anent den titions. How ever, if the perm anent tooth to be restored w ith a steel crow n is grossly carious, occlusal re lationship s m ay be adversely af fected and m ay require adjustm ents before preparing the tooth to be re stored. Figure 1 left is a good exam-
Fig 2 ■ Precem entation radiograph confirm s proxim al m arginal integrity of crown.
C roll-C astaldi : PREFORMED STA IN LESS STEEL CROWNS ■ 645
A R T IC L E S
Fig 3 ■ Rounding angles dur ing preparation. If areas a and b rem ain sharp, crown seating may be hindered. Crown sits well when these areas are rounded.
no gross cervical bulges on perm a nent teeth that facilitate retention of the crow n. Cusp heights are m uch greater in perm anent teeth. A lso, conservation of tooth structure is m ore cru cial for teeth of the perm a nent dentition, as in all probability, a cast gold restoration w ill be in d i cated, w hich m ust not have its reten tion com prom ised during a previous procedure. A n essential step in preparation of the tooth is rounding of all angles. T his inclu d es all axio-occlu sal line angles as w ell as occlu so bu ccal, occlu solin g u al, and occlusoproxim al. Crown seating and accu rate
tapered diam ond or a 169 long car bid e bur for proxim al and m arginal preparation; the other one of us (CRC) frequently uses diam ond disks and stones w ith the straight handpiece at slow speed. Liberal water spray is essential during preparation to elim inate u n pleasant odors, reduce dust from tooth debris, and, m ost im portantly, to lim it iatrogenic therm al injury to vital pulp tissu e s.16 There are anatom ical variations and p ractical considerations that alter the rationale of the preparation for a perm anent tooth com pared with that of a deciduous tooth. There are
Fig 4 ■ Procedure for placing stainless steel crow ns
for
perm anent
posterior
teeth.
A,
occlusal reduction is outlined. B, occlusal and proxim al reduction is completed and pulp pro tection procedures are performed. C, crown was shortened at gingival m argin. Notice how retrac tion of gingival tissue by rubber dam clamp shows open gingival m argins that a re to be recrim ped and recountered. D, additional crim p ing and contouring im prove fit and only sm all buccal area requires more m arginal adaptation. E, w ith rubber dam removed, occlusion m ay be evaluated in all functional movements.
646 ■ JADA, Vol. 97, October 1978
m arginal adaptation are facilitated by this operation4 (Fig 3). Figure 4 show s the procedure for p lacing the steel crown. In itially, the tooth is reduced occlu sally in a sim i lar m anner to the reduction for a cast gold crow n. The general anatom ical form of the crown in reduced d im en sio n s should be m aintained w h ile as suring betw een 1 and 2 m m occlu sal clearan ce in the entire envelope of excu rsive m ovem ents. T h is is achieved readily w ith the barrelshaped diam ond. T he occlu sal re duction is achieved first to facilitate better control and vision for the next step, w hich is the proxim al red u c tion. T h e proxim al slices elim inate all con tact w ith ad jacent teeth and create the space required to adapt the crow n and to restore contact if in d i cated. Proxim al preparation is achieved w ith the flam e-tapered diam ond, or the 169 long carbide bur. It is helpful to place a w ooden wedge or flattened round toothpick betw een
A R T IC L E S
the teeth to prevent in terference of the rubber dam and to avoid lacera tion of the gingiva. T h e next step is to slig htly reduce the convexity of the bu ccal and lin g ual surfaces of the tooth. It is im por tant to reduce these surface con vexities in the gingival third of the tooth so the stainless steel crow n may assum e the original convexity and thus preclud e an overcontoured, en larged b u ccolin gu al dim ension. A fin e, feather-edged gingival m argin at the crest of the gingiva should be produced, w hich w ill be covered by the thinned sm ooth edge of the crow n. W hen caries extends subgingivally, the m argin m ust ex tend subgingivally also to furnish fu ll coverage of the preparation after com plete caries rem oval. T h e edge of the crow n m ust be designed to em brace secu rely the m argin around the entire periphery of the tooth. Caries rem oval is achieved in the conventional m anner w ith spoon ex cavators and slow -speed round burs. Pulpal insulation procedures (bases and varnish application) are now performed. SELECTION AND ADAPTATION OF CROWN. N one of the available com
m ercial crow ns are suitable for every situation. In fact, clin icia n s who are concerned about good occlu sal rela tionship s in restorative dentistry m ay be disappointed w ith the types of crow ns on the m arket. O cclusal m orphology, cusp height, b u cco lin gual w idth, and occlusogingival length vary w idely. Se le ctio n of a sp ecific brand of crow n may becom e easier by having a set of study m odels as part of the p atien t’s perm anent record. Som e prefestooned crow ns are too short occlu so g ingivally in cases in w hich there is deep proxim al caries. M ink and H ill17 described how this defect can be overcom e for the deciduous tooth by spot w elding an additional p iece of crow n or band m aterial. For perm anent teeth, having at least one of the nonfestooned crow ns available is recom m ended rather than restor ing to M in k ’s add-on procedure. The cusp heights of som e types of crow ns tend to be steep and m ore like
new ly erupted molars. T h e occlusal m orphology of other types resem bles older, m ore worn teeth. E con om ic consid erations in office prac tice m ay preclud e having a fu ll sel e ctio n o f all five available brands of crow ns. N evertheless, the wide variation in occlu sal anatom y of teeth necessitates having at least two brands available. O nce a suitable brand has been chosen, there are several ways to select a sp ecific size crow n for a tooth. Som e p ractitioners5,13 advo cate m aking m easurem ents of the prepared tooth, w hereas others use the trial-and-error m ethod. We tend to agree with A lle n 10 in h is observa tion that consid eration of the contra lateral tooth, if possible, com bined w ith trial-and-error is the m ost expe dient m eans of crow n selectio n after exp erien ce is gained w ith the te ch nique. T h e aim is to select a pre form ed crow n that fits snugly over the preparation, that w ill assure rees tablishm ent of proxim al contact, and that w ill perm it the m arginal areas to be crim ped and contoured to assure a tight, ideal, m arginal adaptation. At this p oint in the procedure, the use of the rubber dam is extrem ely im portant. D in er18 recognized the d esirability of observing directly the m arginal areas of the crow n during adaptation. V isualization of every m arginal area is im portant for ideal adaptation and proper use of the rub ber dam; the clam p as a retractor can provide this visib ility . A heavy dam, w ith sm all hole size, aids in retract ing the m arginal gingiva in co n ju n c tion w ith a retraction clam p. T h e interproxim al part of the rubber dam and suitable w edging retracts th e in-
terproxim al gingiva. Proper length of the stainless steel crow n has already been described and may be achieved w ith curved crow n and bridge scissors follow ed by refinem ent w ith a greenstone. Castaldi3 has show n that a com m on error in fabricating a preformed crow n for deciduous teeth is to m ake the crow n too short on proxim al sur faces, predisposing that surface to caries. T his area is norm ally covered by the gingival papilla, but is easily view ed w ith rubber dam retraction of the tissu e (Fig 4C). In adapting the crow n, the original length of the c lin ica l crow n should be recreated. Im portant also is the orientation of the crow n so it reestab lish es the original long axis of the crow n to the tooth,3 w hich w ill be help ful in elim inatin g interfering cusps, and associated m andibular shifts. A fter achievin g proper orientation of the crow n on the tooth, the mar ginal areas are critica lly exam ined. O nly the areas im m ediately below the proxim al contacts cannot be eas ily seen (Fig 4C, 4D). A pair of crow n-crim ping pliers is used to crim p the m argin of the crow n (Fig 5 left). T h ese pliers scal lop the periphery, w h ich is then sm oothed w ith a pair of contouring p liers (Fig 5 right). T h e crim ped crow n is again seated on the tooth and the m argins are reexam ined v i sually and with the explorer. Any open area d isclosed by th is exam ina tion can be marked w ith an ind elible, fine-pointed pen cil or felt-tip marker to ind icate where additional crim p ing and contouring may be n eces sary.
Fig 5 ■ Use of pliers for shaping margins. Left, crimping pliers crimp gingival margin but leave scalloped edge. Right, contouring pliers are used to smooth and contour scalloped margins. C roll-C astaldi : PREFORMED STAIN LESS STEEL CROWNS ■ 647
A R T IC L E S
Fig 6 ■ Establishing correct occlusal relationships. Left, pencil lines indicate prem ature contact of crown. Right, pencil lines indicate that crow n has been seated completely.
W hen ideal adaptation has been achieved, the rubber dam is removed. T h e crow n is reseated and occlu sion is evaluated (Fig 4E). T h e use of a wooden tongue blade split lengthw ise serves as an excellen t bite stick for applying force in a particu lar area w h ile seating the crown. Prem aturities, coronal orientation, length of the crow n, and stability of the restoration are all verified and de ficie n cies are corrected. ESTABLISHING
OCCLUSAL
RELA
TIONSHIPS. T h e patient should not
be left w ith an open bite relationship from a high crow n. To assure that the crow n is not high, it is rem oved and the patient is instructed to close the m outh to fu ll occlusion. A pencil m ark is m ade to record the overbite relationsh ip in the canine area (Fig 6). The crow n is then replaced and the correct relationsh ip is confirm ed. RADIOGRAPHIC CONFIRMATION OF THE GINGIVAL FIT. Before cem enta
tion, a bite-w ing radiograph is taken to verify proxim al m arginal integrity. T h is step is a cru cial one, as seen in Figure 2. If the crow n is too long, there is still an opportunity to reduce the length. If it is too short, the add-on procedure or adaptation of another crow n is indicated. FINAL FINISHING AND CEMENTA TION. After all occlusal and gingival
adjustm ents have been accom plished , it m ay be necessary to re 648 ■ JADA, Vol. 97, October 1978
crim p the crow n as the m etal may expand m inutely each tim e the crow n is seated and rem oved. The m argins of the crow n are then refined and sm oothed w ith a greenstone and a large rubber w heel that rem oves all scratches. F inal treatm ent of the m argin can be accom plished readily by buffing w ith a rag w heel and tripoli abrasive and then polishing w ith jew eler’s rouge. It is most im portant to thoroughly clean the interior of the crow n with a w et cotton swab or sm all brush b e fore cem entation. Three types o f cem ent w idely used for cem entation of the stainless steel crow n are zin c oxyphosphate, polycarboxylate, and zin c oxide and eugenol. After suitable pulp treat m ent, any of these cem ents are ac ceptable. T h e rubber dam is replaced and the tooth is cleaned and dried w ith a lib eral water spray and gentle ap p lica tion of warm air. A cream y m ixture of cem ent is prepared and the crow n is then filled about three quarters full, m aking sure that all m argins are cov ered. It is then seated on the tooth w ith gentle finger pressure or w ith a tongue blade and m ild biting force. E xcess cem ent is expressed around the m argins. T he rubber dam is now removed; the interproxim al rubber is snipped w ith a pair of scissors. T h e previ ously established occlu sal relation ships and the crow n orientation on the prepared tooth can now be ver
ified. D eviations can be corrected be fore the cem ent hardens. R ecreation of cen tric o cclu sion is confirm ed w ith use of a pen cil lin e on the an terior teeth. T h e cem ent is allow ed to set for several m inutes w h ile the p a tien t bites gently on a 2-in square gauze sponge. T reatm ent of the surrounding soft tissu e is im portant both during and after th e procedure. An id eally adapted crow n, w ith sm ooth and polished m argins, rep licatin g the hard tissu e architecture w h ich once existed , is param ount for potentiat ing optim al gingival health (w ritten com m un ication, E. B. Brooks, A pril 1 9 7 7 ).14 Rem oval of excess cem ent is im portant to prevent gingival irrita tion.
L o n g e v ity o f s ta in le s s steel c ro w n fo r p e rm a n e n t te e th T he m ajor factors concerning the longevity of the crow n are gingival recession, recurrent m arginal caries, dissolution o f the cem ent, and w ear ing through on the occlu sal surface of the crown. T h e only report of the long-term potential of the stainless steel crow n for perm anent teeth is by K im m elman and R ie sn e r.15 T hey review ed 65 restorations of w h ich 13 had b een in the m outh from 4 9 to m ore than 120 m onths. No description of clin ical techniqu e is inclu d ed in th eir obser vations. O ne steel crow n was observed by
A R T IC L E S
one of us (TPC) in 1973 in the m outh of a 42-year-old A m erican soldier. T h e restoration had been placed on a m axillary m olar in 1 9 5 8 , according to the m ilitary dental records. No signs of gingival inflam m ation were evident, and although w ear facets existed on the occlusal surface, none of them was worn through the m etal. A sm all area of recession of the palatal gingiva was evident, expos ing about 1 mm of root surface; how ever, the crow n m argin was w ell adapted in that area. It was unfortu nate that the contralateral m olar was absent, so that the tooth w as unable to be view ed for palatal recession in an analagous area. T h e patient re ported no sym ptom s during the en tire 1 5-year history of the restoration. We do not recom m end the use of the preform ed stainless steel crow n for perm anent teeth as a substitute for the p recision cast restoration. Rather, it is our intention to ou tline certain unique situations in w hich the pre form ed crow n, w hen carefu lly done, can be a respectable interim restora tion until a more desirable fu ll cast crow n is possible.
1. Humphrey, W.P. Uses of chrome steel in children’s dentistry. Dent Survey 26:945 July 1950. 2. Braff, M.H. A comparison between stain less steel crowns and multisurface amalgams in primary molars. J Dent Child 42:474 NovDee 1975.
3. Castaldi, C.R. Operative dentistry. In Goldman, H.M., and others (eds.J. Current therapy in dentistry. St. Louis, C. V. Mosby, 1966, vol 2, pp 621-655. 4. Finn, S.B . C linical pedodontics, ed 3. Philadelphia, W. B. Saunders, 1967, pp 184186. 5. Full, C.A.; Walker, J.D.; and Pinkham, J.R. Stainless steel crowns for deciduous molars. JADA 89:3 6 0 Aug 1974. 6. Henderson, H.Z. Evaluation of the pre formed stainless steel crown. J Dent Child 40:353 Sept-O ct 1973. 7. McDonald, R.E. Dentistry for the child and adolescent, ed 2. St. Louis, C. V. Mosby, 1974, pp 206-209. 8. Rapp, R. A sim plified yet precise technic for the placem ent of stainless steel crowns on primary teeth. J Dent Child 33:101 March 1966. 9. Troutman, D.C. Chrome steel crowns: a sim plified self-assessm ent technique. J Acad Gen Dent 24:28 May-June 1976. 10. Allen, K.R. Restoration of the extensively carious primary molar. Aust Dent J 16:8 Feb 1971.
11; Helm, H.W. Sim plified procedure for stainless steel crowns in paedodontics. J Can Dent Assoc 29:369 June 1963. 12. Law, D.B.; Lewis, T.M .; and Davis, J.M. An atlas of pedodontics. Philadelphia, W. B. Saunders, 1969, pp 181-186. 13. Mink, J.R., and Bennett, I.C. The stainless steel crown. J Dent Child 35:186 May 1968. 14. Webber, D.L. Gingival health following placem ent of stainless steel crowns. J Dent Child 41:186 May-June 1974. 15. Kimmelman, B .B ., and Riesner, A.L. Soft stainless steel crown as an interm ediate restora tion: observations in clinical practice. Gen Dent 25:21 July-Aug 1977. 16. Langeland, K. Biologic considerations in operative dentistry. Dent Clin North Am 125:131 March 1967. 17. Mink, J.R., and H ill, C.J. M odification of the stainless steel crown for primary teeth. J Dent Child 38:197 May-June 1971. 18. Diner, H. An improved technique for gingival adaptation of the stainless steel crown. J Dent Child 33:266 July 1966.
THE AUTHORS
Dr. Croll is a resident in pediatric den tistry and Dr. Castaldi is chairman of the department of pediatric dentistry at the University of Connecticut Health Cen ter, Farmington, 06032. Address re quests for reprints to Dr. Castaldi.
CROLL
CASTALDI
C roll-C astaldi : PREFORMED STA IN LESS STEEL CROWNS ■ 649
