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Splinting: Theory and Practice
Splinting: theory and practice Marvin Simring, D.D.S., Brooklyn, N. Y . Splinting, the binding together of teeth for mutual support, has stood the practi cal test of time for 45 centuries. In order to reap the fullest benefits, however, and avoid the possible pitfalls in splinting, the biomechanics of its operation must be understood, especially the immediate ef fect of pressure on the teeth. M O V E M E N T S OF TE ETH UN DER O C C L U S A L LOAD
Stuteville1 sectioned the jaws o f freshly killed dogs and monkeys and took motion pictures through a microscope as the teeth were pressed buccally and lingually. One root was left embedded completely and the other was sectioned buccolingually. He reported as follows: ' It was observed that the one-rooted teeth moved with their point of least movement or fulcrum at the junction of the apical one-third with the crown two-thirds of the root. . . . In multi-rooted teeth, the center o f rotation is in the alveolar septum. When a lower molar is tipped mesially, the mesial root is pressed into the alveolus, and the distal root is elevated.
This, in essence, is the basis of splint ing, for it transforms several single-rooted teeth into a new multirooted “ super tooth” whose roots do not individually tilt, but are rather pressed into the alveo lus, or elevated. Stuteville1 further stated:
[periodontal] fibres resist the movement (ex cluding the apical group and free gingival group). When the tooth is tipped the greatest pressure is brought to bear upon a small area of fibres at the crest of the side of force and on the opposite side of the apex. . . . It is ob vious that more fibres are tightened in bodily movement than in tipping movement; there fore more force can be used safely.
Thus splinting appears to be the ra tional safety procedure to employ when a tooth must withstand forces beyond its individual physiologic limit. The patho logic tilting of the individual tooth is transformed by splinting into a physio logic bodily movement analogous to the bodily movements of the roots of multi rooted teeth. Individual tooth movement is not obliterated by splints and fixed ap pliances as some have thought.2 On the contrary, it is directed so that the entire periodontal membrane is stimulated fairly uniformly. Thus splinting is a biologic procedure. Since a splint distributes the support ing force of the tooth more uniformly, there will not be as much movement by any one part of the tooth’ s supporting periodontal membrane as there had been prior to splinting. Therefore the tooth will appear tighter after splinting. Presented in a sym posium b efore th e Section on P e riodontia c o m b in e d w ith th e S ection on O p e ra tiv e D entistry, ninety-second annua! session o f th e A m e ri can Dental A sso ciation , W a s h in g to n , D. C ., O c to b e r 17, 195). 1. S tu te v ille , O . H ., O rth o d o n tia studies. N o rth w e s t ern U n iv. Den. Res. & G ra d . Q u a r. Bui., M ay 6, 1935. 2. M c C a ll, J. O ., a " d H u g e l, I. M . M o v a b le -re m o v a b le b rid g e w o rk . Brooklyn, Denta! Item s o f Interest Pub. C o ., 1950.
When the tooth is pushed into its alveolus, as in mastication practically two-thirds of the 402
S IM R IN G . . . V O L U M E 45, OCTOBER 1952 • 403
T h e general biolo g ic p rin cip le s o f s p lin tin g are: 1. R e d u ctio n o f p e rio d o n ta l stra in and tig h te n in g o f teeth. 2. P hysiologic re -o rie n ta tio n o f to o th movem ents fro m p a th o lo g ic tiltin g to s tim u la tin g v e rtic a l b o d ily resistance.
R E S IS T A N C E T O M E S IO D IS T A L T IL T IN G FO R C E S
T h e s p lin t effect occurs th ro u g h use o f any appliance w h ic h ties several teeth to ge ther rig id ly . A m esiodistal fo rce ap p lie d to a s p lin t o r statio n a ry brid g e w ill act like force M in F igure 1. I t w ill tend to ro ta te the en tire u n it o f teeth and ap p liance about an axis (m ) ru n n in g be tw een the teeth (a t rig h t angles to the force in itia tin g the m ovem e n t) . T h e in d iv id u a l roots cannot t i l t as separate units b u t m ust m ove m ore v e rtic a lly and bodily. T h is utilizes the m a x im u m s ta b ili zation available th ro u g h s p lin tin g in re sisting forces th a t tend to t i l t teeth mesiodistally.
D IS T A L A B U T M E N T S
T h e d istal tiltin g force o f a free end saddle p a rtia l denture m a y be p e riodonta lly pathogenic fo r a bicusp id to w h ic h i t is clasped. T h a t force m ig h t be oriented p h ysiolog ically i f the b icuspid were splinted to the to o th mesial to it.
C A N T IL E V E R BRIDGES
V e rtic a l occlusal pressure fa llin g outside the lo n g axis o f the to o th induces tiltin g s im ila r to th a t resulting fro m h o riz o n ta l (m esiodistal) strain. T o p re ve n t this, s p lin tin g can be u tiliz e d to support some ca n tile ver bridges. T h u s a m issing second m o la r can be replaced w ith a sm all a r tifi cia l p o n tic supported b y a sp lin t-b rid g e attached to th e firs t m o la r, second b i cuspid and firs t bicuspid.
Fig. I ’ M indicates mesiodistal fo rces; dotted line "m ” indicates axis betw een the tee th ; B indicates buccolingual fo rces; dotted line " b ” indicates axis which runs through both teeth
R E S IS T A N C E T O B U C C O L IN G U A L T IL T IN G F O R C E S
A b u cco lin g u a l fo rce (fo rc e B in Figure 1) tends to t i l t th e s p lin t in a b u c c o lin gual d ire c tio n abo u t an axis o f ro ta tio n (d o tte d lin e b ) th a t runs m esiodistally th ro u g h b o th teeth. T h e re su ltin g t i l t is essentially the same as the t i l t o f u n sp linted teeth. T h e re is, o f course, the m echanical advantage o f h a v in g the stra in shared by tw o te e th ; how ever, the u n h e a lth y d is trib u tio n o f forces a p ica lly and c e rv ic a lly s till exists and there is n o t the m echanical u n ifo rm ity o f stress dis trib u tio n fo u n d in the s p lin t’s resistance to m esiodistal tiltin g . T h u s the s p lin tin g e ffect is least in its resistance to bucco lin g u a l loads. T h is m ay be counteracted to some e xtent by a p a rtia l den tu re w ith a rig id b a r w h ic h w o u ld p it the le ft and rig h t splints against each other. B U C C O L IN G U A L D IA M E T E R O F T E E T H
I n o rd e r to enhance th e s p lin t’s re d u ctio n o f occlusal tra u m a in th e b u cco lin g u a l d ire c tio n o th e r technics fo r the a lle v ia tio n o f tra u m a tic occlusion should be u tilize d . T h e s p lin t restorations should be n a rro w b u cc o lin g u a lly in o rd e r to reduce the to rq u e re su ltin g fro m occlusal forces
.404 • THE JO U R N A L OF TH E A M E R IC A N DENTAL A S S O C IA T IO N
P
a distinct advantage over splinting teeth in a straight line. R E S IS T A N C E T O R O T A T IO N A B O U T T H E L O N G A X IS O F T H E T O O T H
Fig. 2 • P and L are labiolingual forces; 2 and 7 indicate axes
which fall outside the long axis of the tooth. Naturally, complete occlusal equilibra tion should always be instituted before splinting is undertaken. S P L IN T IN G A R O U N D T H E A R C H
Since occlusal forces are multidirectional (mesiodistal and buccolingual), an ideal splint would have to run not only mesiodistally but also buccolingually. Carrying the splint around the curve of the dental arch approaches this ideal of multidirec tional splinting, of having the occlusal stress applied in the direction of the splint rather than at a right angle to it. In Figure 2 labiolingual force P falling on the central incisor tends to rotate the splint labially about an axis (2) running labiolingually. Since the central incisor and cuspid are not in one labiolingual line the axis (2) cannot run through both teeth but is located between them. Thus simple individual tooth tilting is impossi ble and bodily movement of the roots results. The same analysis can be applied to labiolingual force L which tends to produce bodily movement by rotating the splint around the dotted line 1 as the ful crum. Thus splinting around the arch has
In certain periodontal conditions teeth may drift, elongate or rotate. After the teeth are realigned in the dental arch they may require splinting because o f the di minished periodontal support. When the pathologic force causes rotation, as, for example, the rotation o f the lateral in cisor away from the central incisor as shown in Figure 3, the tooth may tend to move out again after realignment. The rotation may be considered analogous to a door swinging open. When it is closed it would be locked at the side which had opened the most and not near the hinges. Likewise, the rotated tooth, after realign ment, is “ locked” by splinting to the tooth from which it moved. In Figure 3 this would be the central incisor. If this sup port were considered inadequate because the central incisor was weak, then the cuspid might be included in the splint for added support just as a door may be immobilized by bolting it on both sides. I f the lateral incisor were splinted to the cuspid alone, it would be analogous to placing the door lock near the hinges. This lock could easily be forced. Figure 4 shows a rotated tooth which was realigned and erroneously splinted to the cuspid with three-quarter crowns soldered to gether. The tooth rotated out again. The rule is: a rotated tooth, which is realigned and requires splinting, should be splinted to the tooth from which it has moved most; for greatest support it may be splinted to the teeth on both sides of it. D IS T A N C E A N D T H E S P L IN T IN G E F F E C T
The effectiveness of the splinting action in a mesiodistal direction results from the buccolingual direction o f the axis o f ro tation, which obviously cannot run through both teeth simultaneously and
S IM R IN G . . . V O LU M E 45, OCTOBER 1952 • 405
therefore cannot p e rm it in d iv id u a l t i l t in g o f each to o th , b u t involves u n ifo rm m ovem ent o f b o th teeth. W hen the teeth are fu rth e r ap a rt, th e arc o f this m ove m e n t increases and induces a m ore n e a rly v e rtic a l resistance w h ic h is desirable. T h e fa rth e r a p a rt th e teeth are, however, the w eaker the b u cco lin g u a l s p lin tin g effect is because a s lig h t t i l t in one to o th w ill p e rm it a large m ovem ent in the o th e r as i f one to o th were ro ta tin g about the o th e r as a d ista n t fu lc ru m . T h u s the u n ify in g o r s p lin tin g a ctio n dim inishes as a w id e r la titu d e o f in d epe nden t to o th m ovem ent is p e rm itte d by d ista n t abutm ents. T h e re fo re w hen three o r m ore m issing posterior teeth are replaced, the s p lin tin g effect m ust be increased by in c lu d in g at least three abutm ents w hen opposed by the n a tu ra l d e n titio n o r a sta tio n a ry bridge (F ig . 5 ).
R IG ID IT Y A N D T H E S P L IN T IN G E F F E C T
“ R estorations re p la cin g three o r m ore missing p o ste rio r teeth and e m p lo yin g o n ly tw o abutm ents m ay be considered w hen the opposing d e n tu re is a tissueborne rem ovable a p p lia n ce .” 3 I n th is case the opposing d e n titio n being m ore y ie ld ing, the forces o f occlusion are lo w and th erefore considerable s p lin tin g effect is unnecessary. F u rth e rm o re , the u n y ie ld in g rig id ity o f the s p lin t m a y be dele terious to the rid g e u n d e rly in g the re m ovable denture. T h u s th e decreased m o b ility o f the sp linted to o th m a y cause some d ifficu ltie s. T h e g reater rig id ity o f a s p lin t m a y occa sionally w reak havoc on a weakened op3. The c o n s tru c tio n o f fixed b rid g e s . Led e rle news le tte r. New Y o rk, Led erle L a b o ra to rie s D ivision, A m e r i can C y a n a m id C o ., 1951.
Fig. 3 • A b o v e : A lateral incisor which has rotated away from central incisor because of perio dontal disease. Below le ft: A fter lateral incisor is realigned, it may require splinting to central incisor to prevent it from drifting out again , just as a door must be locked at the part which has rotated most. Below right: For greater stabilization, the splint may include cuspid as well as lateral and central incisors. This is analogous to barring a door on both sides in addition to locking
406 • THE J O U R N A L O F TH E A M E R IC A N DENTAL A S S O C IA T IO N
Fig. 4 • A bove left: Lateral incisor which drifted away from central incisor. A bove right: Lateral incisor realigned with stainless steel ligatures. B elow : T ooth splinted to cuspid with soldered three-quarter crowns. Slight rotation of lateral incisor is apparent
posing to o th . F o r exam ple, a second m o la r m ay be rig id ly sp linted to a firs t m o la r to preve nt extrusio n and fo o d im p a c tio n w here the opposing second m o la r is miss ing. I f the opposing firs t m o la r is a lone to o th th a t m ust also su p p o rt the load o f a p a rtia l d e nture atta ch m e n t, occlusal tra u m a m ay re su lt u p o n th is weakened firs t m o la r. I t is w iser to e xtra ct th e sec ond m o la r i f i t interferes in any w a y o r to e xtra ct th e a d ja cen t firs t m o la r i f its prognosis is d o u b tfu l and replace i t w ith a fixe d bridge. T H E PR A C T IC E O F S P L IN T IN G
Non-shrinking Waxed Silk Ligature
4-6 • A double loop is tie d around the firs t
to o th and secured w ith a surgeon’s knot. E ach re m a in in g to o th , in tu rn , is tied w ith a single loop secured a t the ne xt in te rp ro x im a l space w ith a nother sur geon’s kn o t. O n the p ro x im a l surfaces the lig a tu re is placed so th a t i t is g in g iv a l to th e c o n ta ct p o in t (w idest m esiodistal d ia m e te r ); la b ia lly and lin g u a lly i t is in cisa l to th e c in g u lu m (w id e st la b io lin gual d ia m e te r ); thus the lig a tu re is
4. M ille r , S. C . Textbook o f p e rio d o n tia , e d . 3. P h ila d e lp h ia , B lakiston C o ., 1950, ch. 17. 5. H irs c h fe ld , L. The use o f w ire and s ilk lig a tu re s . J .A .D .A . 41:647 (D e c .) 1950. 6. S o rrin , _S. The use o f fix e d and re m o v a b le splints in the p ra c tic e o f p e rio d o n tia . A m . J. O rth o d o n t. & O ra l S urg. (O ra l Surg. Sec.) 31:354 (June) 1945.
S IM R IN G . . . V O L U M E 45, OCTOBER 1952 • 407
Fig. 5 • Fixed bridge replacing second bicuspid and first and second molars attached with cast gold crowns to cuspid, first bicuspid and third molar (Sept. 27, 1947)
Showing im proved health of alveolar bone (D ec. 30, 1950)
secure. I t cannot slip g in g iv a lly o r in cisally. I n o rde r to a vo id tra c tio n and possible d riftin g o f the teeth w here the teeth do n o t contact one another, a su fficie n t n u m ber o f knots m ay be tie d in te rp ro x im a lly u n til the next a djacent to o th is reached. Instead o f m u ltip le knots, a single k n o t m ay be tie d adja cent to each to o th and the in te rp ro x im a l lig a tu re m a y be em bedded in a sm all piece o f q u ic k -c u rin g a crylic resin a p p lie d a fte r the lig a tu re has been com pletely tied. T h is w ill also add to the strength and security o f the s p lin t w h ile s im p lify in g its a p p lic a tio n . Because o f the absorption o f fo o d debris and saliva, the lig a tu re tends to become
fo u le d and m ay need to be changed every tw o weeks o r m ore ofte n . T h is absorption can be decreased and the d u ra b ility in creased by firs t p a in tin g the d rie d to o th surfaces w ith sandarac va rn ish and then, a fte r ty in g the s p lin t, a p p ly in g a second coat o f varnish. Because a ll splints w h ic h the p a tie n t cannot rem ove m ay in te rfe re w ith ade quate to o th b ru sh in g , an advisable o ra l sa n ita tio n a d ju n c t is a device fo r fo rc e fu l w a te r irrig a tio n o f the m o u th , as sug gested by M ille r ,7 w h ic h m a y be attached to th e fa u c e t; fo r exam ple, a com m ercial shower attachm ent. W h ile silk ligatures are ra p id ly and easily a p plied, th e ir d u ra b ility and rig id ity are low . F u rth e rm o re lig a tio n is generally lim ite d to the six a n te rio r teeth because o f th e ir anatom y. P osteriorly, the anatom y o f the teeth perm its the lig a -
7. M ille r , S. C ., O ra l d iagnosis and tre a tm e n t p la n n ing, ed. I. P h ila d e lp h ia , Blakiston C o., 1936, p. 256.
408 • TH E J O U R N A L O F THE A M E R IC A N DENTAL A S S O C IA T IO N
5. S tabilize teeth u n til a m ore p e rm a ne n t type o f s p lin t is constructed. 6. S tabilize teeth w ith questionable prognosis u n til the results o f tre a tm e n t in d ica te w h e th e r the to o th m ay be re tained. 7. S tabilize, fo llo w in g th e ir re p o sitio n ing, tee th w h ic h had m ig ra te d , ro ta te d o r e xtru d e d as a result o f p e rio d o n ta l dis ease. These m ay also be considered fo r a ll te m p o ra ry splints. T h e type chosen de pends on the fo llo w in g fa c to rs : s im p lic ity o f a p p lic a tio n , d u ra b ility re q u ire d , rig id ity re q u ire d , lo ca tio n, esthetics, o ra l sanitation and p a tie n t cooperation.
Wire Ligature*'6'6'10
Fig. 6 • A b o v e : A rch or circum ferential wire, 0.020 inches diameter, secured with interden tal wires o f finer gage, 0.007 inches diameter. Below : A rch or circum ferential wire consisting of tw o strands of 0.010 inches stainless steel ligature
tu re to slip g in g iv a lly so th a t the s p lin t is loosened and m ay irrita te the gingiva. L ig a tu re m ay be used, how ever, fo r s p lin t in g posterior teeth w hen the necks o f the teeth are constricted o r the roots are heavy.
Indications
• S ilk is va lu a ble as a s p lin t w he n i t is requ ire d o n ly fo r a m a tte r o f weeks in o rd e r to : 1. S tabilize a to o th w ith acute perice m en titis. 2. S tabilize a to o th loosened by a blow . 3. S tabilize loose teeth in o rd e r to a void undue in ju r y o r d isco m fo rt to th e m caused b y in stru m e n ta tio n , p e rio d o n ta l surgery o r g rin d in g to relieve occlusal pressure. 4. S tabilize teeth d u rin g p e rio d o n ta l tre a tm e n t in o rd e r to pro m o te h e a lin g and possible rca tta c h m e n t o f the su p p o rt in g tissues.
• W ire lig a tu re , lik e silk lig a tu re , is lim ite d generally to the a n te rio r teeth fo r ana to m ic reasons. I t is stronger th a n silk b u t takes lo n g er to apply. I t is m ore du ra b le th a n silk and m ay even be retained fo r several years o f tre a tm e n t and observation. W ire lig a tu re is n o t esthetic, however, and w h ile i t does n o t absorb flu id s i t tends to catch food p a rticle s and is d iffic u lt to keep clean. A c c id e n ta l breakage o r u n tw is tin g o f the w ire m ay expose sharp edges w h ic h i r r i ta te the lips, cheeks, tongue and gin g iva . V a rio u s types and gages o f w ire have been suggested in the lite ra tu re . A dead soft stainless steel lig a tu re e ith e r 0.020 inches in d ia m e te r (F ig . 6, above) is satisfactory, o r w here greater fle x ib ility and ease o f a p p lic a tio n are needed, tw o strands o f 0.010 inches as the a rch w ire (F ig . 6, b e lo w ). In te rd e n ta l w ires are 0.007 inches in diam eter. T h e arch w ire is looped aro u n d a ll the teeth to be in cluded in the sp lin t, ro u g h ly adapted to the teeth, and the ends are tw iste d to ge th e r lig h tly . L ik e silk lig a tu re , the steel is k e p t g in g iv a lly to th e con ta ct p o in t
8. Rhein, M . L. S p lin tin g loosened te e th in pyorrhea a lv e o la ris . D. Cosmos 45:369 (M a y ) 1903. 9. Sm ith, R. C o n s tru c tio n o f a s p lin t in p e rio d o n ta l tre a tm e n t. D. D igest 47:118 (M a rc h ) 1941. 10. Barkann, L. The case fo r m e ta l lig a tu re s in p e rio d o n tia . J . 2nd D ist. D. Soc. (N .Y .) 31:341 (D e c .) 1945.
S1MR1NG . . . V O L U M E 45, OCTOBER 1952 • 409
and in cisally to the cin g u lu m . Strands o f the th in n e r gage w ire , about one and a h a lf inches long, are bent like h a irp in s w ith one a rm lo nger th a n the other. Each in te rd e n ta l “ h a irp in ” is inserted fro m the lin g u a l side w ith the lo n g er a rm g in g iv a l to the arch w ires and the shorter a rm between the a rch wires and the con ta c t p o in t. U s in g a hem ostat o r fine beaked pliers, each in te rd e n ta l w ire is tw isted tig h t clockwise. O v e rtw is tin g w ill cause breakage. T h e ends o f a ll the wires are then cut, le a vin g about 3 o r 4 m m . o f the tw isted ends stickin g o u t. These are th e n curled a ro u n d the end o f a broken in s tru m e n t w ith an am algam plugger. T h e in s tru m e n t is w ith d ra w n and the little loop o f w ire is then tucked, w ith the p lugger, in to the in te rp ro x im a l em brasure to a void soft tissue irrita tio n . S hould the s p lin t become loose at any tim e , these lit tle w ire loops m ay easily be tightened. T h e arch w ire fre q u e n tly slips in cisa lly o ff the d ista l aspect o f the cuspids be cause o f an open contact o r because the to o th is conical in shape. T h is slipping m ay be prevented by a cervica l re ta in in g w ire loop as described by H irs c h fe ld .5 A piece o f th in gage w ire is placed around the neck o f the cuspid o r around the neck o f the firs t bicuspid (F ig . 6, b e lo w ), i f the cuspid is too conica l to re ta in this w ire , and d ra w n tig h t w ith ab o u t three twists. O ne strand is n o w placed u n der the arch w ire on the d istal aspect o f the cuspid and the o th e r strand o f the re ta in in g loop is placed over the arch w ire and then b o th strands are tw isted together enclosing the arch w ire . T h e tw isted end o f the re ta in in g w ire is c u t short and cu rle d away in te rp ro x im a lly . T h e ta u t w ires m ay tend to d ra w the teeth together in to th e smallest possible arc. T h e re fo re , w here the teeth are n o t in conta ct m esiodistally, the in te rd e n ta l space m ay be taken u p by tw is tin g the arch w ires together to brid g e the space or, as w ith the silk ligatures, a sm all piece o f q u ic k -c u rin g a c ry lic resin can be
Fig. 7 • Extradental acrylic resin splint ap plied directly betw een the teeth while toothcolored acrylic resin is soft
placed to b rid g e the space between tw o teeth, e n veloping the a rch wires. T h e w ire s p lin t’ s p o o r esthetics and its possible ir r ita tio n to the lip m ay be over come by a p p ly in g a th in layer o f to o th colored q u ic k -c u rin g a c ry lic over the la b ia l a rch w ire a fte r the s p lin t is com pleted. T h e shadow o f the wires m ay be obscured by firs t p a in tin g th e m w ith an o p a cifie r paste m ade o f lig h t ye llo w zinc oxyphosphate cem ent p o w d er plus a fe w drops o f the a c ry lic m onom er, and then a p p ly in g the fre sh ly m ixe d a c ry lic resin. T h e se lf-curin g a crylic resins m a y also be used so as to p e rm it the use o f w ire lig a tu re splints p osteriorly. A fte r the ap p lic a tio n o f the d o u ble-strand a rch o r c irc u m fe re n tia l w ire , i t is secured in place w ith sm all plugs o f the self-curing a crylic resin placed in each in te rp ro x im a l embrasure, buccal as w e ll as lin g u a l, engaging and enclosing the a rch w ire. O nce these plugs set they w ill prevent occlusal o r g in g iv a l m ovem ent o f the arch wires. I f there is a tendency fo r the arch w ire to slip g in g iv a lly d u rin g its a p p lic a tio n i t can be secured w ith sepa rate strands o f w ire w h ic h ru n fro m buccal to lin g u a l across the occlusal surface. B oth buccal and lin g u a l strands o f the arch w ire are engaged and are d ra w n ta u t. These accessory b u cco lin g u a l wires m ay be c u t o ff a fte r the a rch w ire has been secured w ith the p ro x im a l a crylic plugs.
Extradental Plastic
• A m e th o d recently advocated by S o rrin can be used where there is adequate space between the lo w e r incisors (F ig . 7 ). T o o th -c o lo re d q u ick-
410 • T h e J O U R N A L O F TH E A M E R IC A N DENTAL A S S O C IA T IO N
Fig. 8 • L e ft: Stainless steel wire, 21 gage, adapted to stone cast. Self curing acrylic resin is processed over this. R ight: C om pleted surgical apron-splint in place in patient’ s mouth
c u rin g a c ry lic resin is freshly m ixe d and fo rm e d in to a s trip w h ic h is placed lin g u a lly and pushed la b ia lly th ro u g h the in te rd e n ta l spaces. A la b ia l core o f im pression com po u n d m ig h t be made in i tia lly to stabilize the teeth d u rin g the procedure. U n fo rtu n a te ly , this esthetic, stable, and sim p ly a p p lie d s p lin t can be rem oved o n ly by g rin d in g i t off.
Intradental Plastic
• O b in and A rv in s 11 advocate a h ig h ly esthetic, fa irly stable m eth od o f te m p o ra ry s p lin tin g w h ic h is o f value w here a m ore perm a n en t restora tio n w ill be in d ic a te d i f the teeth can be retained. A fte r the teeth are ligated w ith d e n ta l floss fo r s ta b ility, a plaster o r com pound core is m ade and th e n an u n d e rc u t groove is prepared in th e teeth (lin g u a lly in an te rio r te e th ; occlusally in posterior teeth) and this is packed w ith self-curing resin w h ic h is he ld in place by the core u n til i t has set. A c c o rd in g to O b in and A rv in s , superior m a rg in a l a d a p ta tio n can be obtained by m a k in g in d iv id u a l m esiolinguodistal res tora tio ns in se lf-c u rin g a crylic resin fo r each to o th and th e n u n itin g th e m a ll w ith m ore o f the resin.
Soldered Bands 6
• Each to o th is banded and th e in d iv id u a l bands are soldered together and cem ented to place. T h is is used fre q u e n tly to p ro v id e the resistant fo rce re q u ire d fo r m o vin g teeth o rth o d o n tic a lly . I t is uncsthetic b u t provides good sta b iliz a tio n , a lth o u g h bands do occasionally loosen because o f occlusal pressure. E xc e lle n t c o n to u rin g is essential to a vo id g in g iv a l irrita tio n and dental caries.
Removable Cast M etal
6,12 • A c o n tin u ous cast clasp s p lin t, as advocated o rig i n a lly by M ille r ,4 w h ic h encircles the teeth a t th e ir heights o f c o n to u r b u cca lly and lin g u a lly can be cast in go ld o r chrom eco b a lt a llo y and affords an excellent te m p o ra ry s p lin t. In te rfe re n ce w ith occlusion m ust be avoided. T h e y are m ore rig id th a n lig a tu re s a n d m a y be rem oved by the p a tie n t fo r cleaning. E sthetically, how ever, they are poor. T h e continuous clasp s p lin t is fr e q u e n tly used as p a rt o f a rem ovable p a r11. O b in , J. N ., and A rvins, A . N. The use o f selfc u rin q resin s p lin ts f o r th e te m p o ra ry s ta b iliz a tio n o f m o b ile te e th due to p e rio d o n ta l in v o lv e m e n t. J .A .D .A . 42:320 (M a rc h ) 1951. 12. Schweitzer, J . M . O ra l re h a b ilita tio n . St. Louis, C . V. M osby C o ., 1951.
SI MRI NO . . . V O L U M E 45, OCTO BER 1952 • 411
tia l d e n ture so th a t the s p lin tin g effect o f m u ltip le abutm ents m ay be u tiliz e d fo r the su p p o rt o f a rtific ia l teeth and, occasionally, to supp ort some w eak n a tu ra l teeth at the same tim e. T h e s p lin t in g effe ct m ay be enhanced by in c o r p o ra tin g in to the appliance, attachm ents w h ic h fit rig id ly in to slots in inlays o r crow ns on the teeth. Precision a tta c h ments o r precision lugs resting in p re c i sion lu g seats are thus o f great value. In o rd e r to a tta in o p tim u m efficiency in the rem ovable d e n tu re -sp lin t by ca rry in g the s p lin tin g effect arou nd the arch, a rig id b a r is essential.
Removable Plastic Splints 4' 6,13
• T h e es th e tic disadvantage o f th e cast m e ta l re m ovable s p lin t can be overcom e b y the use o f m e th y l m etha cryla te resin. T h is sim ple, inexpensive, esthetic s p lin t is w eaker and b u lk ie r, how ever, th a n the a ll-m e ta l continuous clasp sp lin t. O n a cast o f the p a tie n t’s m o u th , a 21 gage stainless steel w ire is contoured around the teeth above the w idest p o rtio n o f the to o th . I n m a k in g an a n te rio r s p lin t the w ire w o u ld be lim ite d to the lin g u a l sur faces and the d ista l h a lf o f the la b ia l surfaces o f the cuspids. T ra n sp a re n t a c ry lic resin is th e n processed la b ia lly and lin g u a lly w ith the w ire embedded at
Fig. 9 • U pper roentgenogram s made before periodontal pocket treatm ent. G utta-percha points indicate depth of pockets. L ow er left pictu re was made 10 weeks later; low er right figure was made seven months later
a ll p o in ts except a t the distal ends o f the s p lin t w here i t passes in te rp ro x im a lly . T h u s the s p lin t can be rem oved by the p a tie n t fo r cleaning. O cclusion m u st be checked c a re fu lly. T h e s p lin t should be constructed so th a t i t does n o t engage deep undercuts on the teeth since re peated w ith d ra w a l and in sertion by the p a tie n t m ig h t prove tra u m a tic and the salutary s p lin tin g effect w o u ld be negated. S e lf-c u rin g a c ry lic resin also can be used. I t is n e ith e r as strong n o r as dense as the re g u la r heat-cured m e th yl m e th acrylate resin. F ig u re 8 shows w ire w h ic h has been adapted a ro u n d the teeth o f the p a tie n t’s study cast. T h e a c ry lic resin was th e n placed over it. T h e resin was ex tended over the g in g iva to fo rm a sur g ic a l apron. I n this instance the second b icu sp id was so m o b ile th a t i t co u ld be depressed in its socket. T h e d e p th o f the pockets m esially and lin g u a lly are shown in F ig u re 9, above. A fte r th o ro u g h con servative p e rio d o n ta l tre a tm e n t, a fla p o p e ra tio n was p e rfo rm e d lin g u a lly in the bicuspid firs t m o la r region. T h e fla p was he ld in place by the surgical a p ro n -s p lin t w ith o u t the interference o f sutures. T h u s b o th d e n ta l and p e rio d o n ta l tissues were
13. S o rrin, S. A c r y lic s plints fo r loose te e th . P e rio d o n tia Bull., Feb. 27, 1942.
N .Y .U .
412 • THE J O U R N A L O F THE A M E R IC A N DENTAL A S S O C IA T IO N
immobilized. After six weeks the gingival apron portion was cut off and the patient used the .appliance for an additional month as a removable splint. T h e present excellent state of periodontal healing is indicated in Figure 9, below. At this time the lingual gingival sulcus was only 1 mm. deep and could not retain a gutta percha point. Mobility was only slightly greater than normal. Interlocking Inlays • An interlocking inlay-splint consists of an inlay with an extension that fits snugly into a slot in an inlay on another tooth. The interlocking inlay-splint is effective to the extent that the two inlays are rigidly connected. Thus the male part should be long and both parts should fit tightly. The lateral splint ing effect is diminished if lateral play is permitted between the inlays. The male restoration must cover the entire occlusal surface of its tooth since the male inlay is held in place by the female inlay and an uncovered occlusal area would permit the tooth to be depressed in its socket and be detached from the male inlay. Resistance to vertical occlusal pressure is poor in the female section o f this splint. Thus the interlocking inlay provides in complete splinting. Its only indication might be the rare case in which parallel ism prohibits the use of a soldered joint between restorations. Stationary Splints*'*’14 • The stationary splint composed of several three-quarter or full cast crowns or other type of full coverage soldered together is the most durable and efficient splint. Since the splint and teeth are relatively unyielding, considerable internal strain develops within the individual abutment restorations. Smyd15 has shown that a simple M O or M O D inlay may spread as a result of these tensions. The buccal and lingual “ bands” of crowns prevent this spread and avoid possible leaks, loos ening of the splint and caries under the restorations.
Furthermore, full occlusal coverage is essential. Since the splint is unyielding and is rigidly attached to several teeth, it may separate from one of the teeth if occlusal pressure, falling on the tooth surface and not on the splint, depresses that tooth slightly within its alveolar socket and away from the splint. For these reasons, cast crowns are advo cated for stationary splints posteriorly and ordinary inlays are contraindicated. Three-quarter crowns may be used in a mouth that is caries resistant, where the teeth to be splinted “ present good vertical length since the retention of this attach ment is dependent on long grooves. Where short teeth are to be splinted, full crowns, with or without acrylic veneers, are indicated.” 16 For anterior teeth, threequarter crowns or thimbles and porcelain jackets or, where the occlusion is heavy, full castings with porcelain or acrylic resin facings may be employed. The soldered joint between the crowns must be rigid and must be placed close to the occlusal area so the gingival tissue is not impinged on and so adequate oral sanitation is possible. The soldered joint must be fully rounded occlusally and gingivally; narrow capillary spaces which would trap food and saliva must be avoided.17 Diligent home care by the patient is essential where splinting is utilized. The use of a rubber interdental stimulator is indicated where there is gingival reces sion interdentally. A modified Stillman’s method of toothbrushing should be sup plemented by the modified Charter’ s method o f toothbrushing in order to cleanse and stimulate the interdental re-
14. Kabnîck, H . H ., and Elson, M . Prosthetic a id em p lo y in g fix e d b rid g e s a n d splints in p e r io d o n ta lly in v o lv e d te e th . A lp h a O m eg an 44:85 (S e p t.) 1950. 15. Smyd, E. S. D ental e n g in e e rin g as a p p lie d to in la y and b rid g e fa b ric a tio n . New Y ork J . Den. 21:161 ( A p r il) 1951. 16. M ü le r, S. C . Textbook o f p e rio d o n tia . P h ila d e l p hia, B lakiston C o ., 1938, p. 471. 17. G o ttlie b , B., and O rb a n , B. Z ah nfleisch ent zündung und Zah nlocke rung . Berlin, Berlinische Verlagsansta lt, 1933, p. 280.
S IM R IN G . . . V O LU M E 45, OCTOBER 1952 • 413
Fig. 10 • Precocious advanced alveolar atrophy with pockets involving trifurcations o f upper molars and bifurcation of low er left first molar in 23 year old man
gions adequately. A n excellent device fo r o ra l hygiene is th e p a tie n t’ s use o f w a te r irrig a tio n as p re vio u sly suggested. R egu la r professional denta l p ro p h yla xis three times a year is essential. Because o f the d iffic u lty o f p ro p e r o ra l sa n ita tion and d e n ta l in s tru m e n ta tio n in the second and th ir d m o la r in te rd e n ta l region, s p lin tin g is generally avoided be tween these teeth. Esthetics occasionally dem and the use o f a s p lin t composed o f in d iv id u a l porce la in ja cke t crow ns cem ented over g oldth im b le copings soldered together. Cleansa b ility , g in g iv a l stim u la tio n , and freedom fro m g in g iv a l ir r ita tio n are m ore d iffic u lt to a tta in w ith p o rce la in jackets th a n w ith g old cast crow ns faced w ith a crylic resin o r porcelain. W here p o rce la in ja c k e t s p lin tin g is used, some type o f te m p o ra ry s p lin tin g is in d ic a te d d u rin g the in te rv a l between to o th p re p a ra tio n and in sertion o f the com pleted s p lin t. I f te m p o ra ry clear a crylic resin cro w n form s are used, these m ay be jo in e d w ith a lit tle o f the selfc u rin g a c ry lic resin placed at the lin g u o in te rp ro x im a l points. T h is type o f sp lin t can also be used w here teeth are prepared fo r th re e -q u a rte r crowns. A n alternate procedure consists o f ta k in g an im pression w ith alg in a te im pres
sion m a te ria l before the restorative p re p arations are m ade and setting this aside u n til the p reparations are com pleted. T h e n s e lf-cu rin g a c ry lic resin is m ixe d and placed in to the impression in those teeth th a t have been prepared. T h e im pression is then re-inserted, h e ld in place fo r three to five m inutes, and w ith d ra w n before the resin has become com pletely ha rd . I t is p e rm itte d to bench-harden. T h e n i t is rem oved fro m the im pression, trim m e d , polished, and inserted w ith a te m p o ra ry cem ent such as zinc o xid e and eugenol. S im ila r te m p o ra ry crow ns fo r ad ja cen t teeth can be prepared and fused to the firs t ones i f a d d itio n a l teeth are p repared a t a la te r tim e. S ta tio n a ry splints are in d ic a te d w here the m a x im u m s p lin tin g e ffect is essen tia l in o rd e r to re ta in teeth because o f the large a m o u n t o f bone loss o r because the teeth have a tendency to d r ift. A l th o u g h s p lin tin g w ill a id tee th in w ith standing a n o rm a l fu n c tio n a l occlusal load w h ic h m ig h t otherwise prove tra u m a tic to them , C oolidge and H in e 18 state: “ T h e re m ust be a t least o n e -th ird o f the ro o t surrounded by tissue th a t gives
18. C o o lid g e , E. D ., and H ine, M . K. P e rio d o n tia ; c lin ic a l p a th o lo g y and tre a tm e n t o f the p e rio d o n ta l tis sues. P h ila d e lp h ia , Lea & F e b ig e r, 1951, p . 209.
414 • TH E J O U R N A L O F THE A M E R IC A N D ENTAL A S S O C IA T IO N
Fig. 11 • H ealing o f periodontal tissues 18 months later
clinical evidence of health and firmness.” Thus pathosis must be eliminated and a careful diagnosis made before stationary splinting is undertaken. The cast crown stationary splint also may be used for teeth that must withstand an occlusal load greater than normal. This is accomplished by using multiple abut ments for fixed and removable prostheses. According to Kabnick and Elson,14 “ Bone support for two-thirds of the root length is the minimum amount necessary for a single abutment tooth.” Therefore mul tiple abutments must be utilized in many cases where periodontal disease has been present. The excellent healing of the bone which follows such treatment is shown in Figures 10 and 11. Three of the first m o lars had clinical involvement of the root bifurcation. They were extracted and, following conservative periodontal treat ment, were replaced with three fixed bridge-splints attached to both bicuspids and the second molar. The periodontal improvement is apparent in Figure 11. When collapse of the maxillomandibu lar vertical dimension has occurred be cause of extreme wear or drifting of the teeth, the restoration of the lost vertical dimension to its normal height ( “ bite-raising” ) frequently increases the periodontal strain by increasing the extra-
alveolar lever arms of the teeth. Sta tionary splinting is indicated to prevent the periodontal disease that may be the aftermath of increasing the height of the crowns of the teeth. Thus splinting is indicated where the traumatic effects of occlusion are intense and the stimulating physiologic action of occlusal force needs to be improved. It follows that wherever splinting is indi cated, thorough occlusal equilibration is indicated first. Furthermore, the restora tions involved in the splint itself must fulfill the requirements o f occlusal equi libration and harmony with the patient’ s dentition and temporomandibular joint function. S U M M A R Y A N D C O N C L U S IO N
Splints are of value in supporting loose teeth, weakened teeth and strained abut ment teeth. Splints divide occlusal strain over several teeth and direct it physio logically. Although the most effective splinting is attainable only with cast crowns soldered together, there are many indications for the various types of tem porary splints. Splinting may be consid ered to be an adjunct in the treatment and prevention of occlusal trauma.
2566 Ocean Avenue
Stuteville1 sectioned the jaws o f freshly killed dogs and monkeys and took motion pictures through a microscope as the teeth were pressed buccally and lingually. One root was left embedded completely and the other was sectioned buccolingually. He reported as follows: ' It was observed that the one-rooted teeth moved with their point of least movement or fulcrum at the junction of the apical one-third with the crown two-thirds of the root. . . . In multi-rooted teeth, the center o f rotation is in the alveolar septum. When a lower molar is tipped mesially, the mesial root is pressed into the alveolus, and the distal root is elevated.
This, in essence, is the basis of splint ing, for it transforms several single-rooted teeth into a new multirooted “ super tooth” whose roots do not individually tilt, but are rather pressed into the alveo lus, or elevated. Stuteville1 further stated:
[periodontal] fibres resist the movement (ex cluding the apical group and free gingival group). When the tooth is tipped the greatest pressure is brought to bear upon a small area of fibres at the crest of the side of force and on the opposite side of the apex. . . . It is ob vious that more fibres are tightened in bodily movement than in tipping movement; there fore more force can be used safely.
Thus splinting appears to be the ra tional safety procedure to employ when a tooth must withstand forces beyond its individual physiologic limit. The patho logic tilting of the individual tooth is transformed by splinting into a physio logic bodily movement analogous to the bodily movements of the roots of multi rooted teeth. Individual tooth movement is not obliterated by splints and fixed ap pliances as some have thought.2 On the contrary, it is directed so that the entire periodontal membrane is stimulated fairly uniformly. Thus splinting is a biologic procedure. Since a splint distributes the support ing force of the tooth more uniformly, there will not be as much movement by any one part of the tooth’ s supporting periodontal membrane as there had been prior to splinting. Therefore the tooth will appear tighter after splinting. Presented in a sym posium b efore th e Section on P e riodontia c o m b in e d w ith th e S ection on O p e ra tiv e D entistry, ninety-second annua! session o f th e A m e ri can Dental A sso ciation , W a s h in g to n , D. C ., O c to b e r 17, 195). 1. S tu te v ille , O . H ., O rth o d o n tia studies. N o rth w e s t ern U n iv. Den. Res. & G ra d . Q u a r. Bui., M ay 6, 1935. 2. M c C a ll, J. O ., a " d H u g e l, I. M . M o v a b le -re m o v a b le b rid g e w o rk . Brooklyn, Denta! Item s o f Interest Pub. C o ., 1950.
When the tooth is pushed into its alveolus, as in mastication practically two-thirds of the 402
S IM R IN G . . . V O L U M E 45, OCTOBER 1952 • 403
T h e general biolo g ic p rin cip le s o f s p lin tin g are: 1. R e d u ctio n o f p e rio d o n ta l stra in and tig h te n in g o f teeth. 2. P hysiologic re -o rie n ta tio n o f to o th movem ents fro m p a th o lo g ic tiltin g to s tim u la tin g v e rtic a l b o d ily resistance.
R E S IS T A N C E T O M E S IO D IS T A L T IL T IN G FO R C E S
T h e s p lin t effect occurs th ro u g h use o f any appliance w h ic h ties several teeth to ge ther rig id ly . A m esiodistal fo rce ap p lie d to a s p lin t o r statio n a ry brid g e w ill act like force M in F igure 1. I t w ill tend to ro ta te the en tire u n it o f teeth and ap p liance about an axis (m ) ru n n in g be tw een the teeth (a t rig h t angles to the force in itia tin g the m ovem e n t) . T h e in d iv id u a l roots cannot t i l t as separate units b u t m ust m ove m ore v e rtic a lly and bodily. T h is utilizes the m a x im u m s ta b ili zation available th ro u g h s p lin tin g in re sisting forces th a t tend to t i l t teeth mesiodistally.
D IS T A L A B U T M E N T S
T h e d istal tiltin g force o f a free end saddle p a rtia l denture m a y be p e riodonta lly pathogenic fo r a bicusp id to w h ic h i t is clasped. T h a t force m ig h t be oriented p h ysiolog ically i f the b icuspid were splinted to the to o th mesial to it.
C A N T IL E V E R BRIDGES
V e rtic a l occlusal pressure fa llin g outside the lo n g axis o f the to o th induces tiltin g s im ila r to th a t resulting fro m h o riz o n ta l (m esiodistal) strain. T o p re ve n t this, s p lin tin g can be u tiliz e d to support some ca n tile ver bridges. T h u s a m issing second m o la r can be replaced w ith a sm all a r tifi cia l p o n tic supported b y a sp lin t-b rid g e attached to th e firs t m o la r, second b i cuspid and firs t bicuspid.
Fig. I ’ M indicates mesiodistal fo rces; dotted line "m ” indicates axis betw een the tee th ; B indicates buccolingual fo rces; dotted line " b ” indicates axis which runs through both teeth
R E S IS T A N C E T O B U C C O L IN G U A L T IL T IN G F O R C E S
A b u cco lin g u a l fo rce (fo rc e B in Figure 1) tends to t i l t th e s p lin t in a b u c c o lin gual d ire c tio n abo u t an axis o f ro ta tio n (d o tte d lin e b ) th a t runs m esiodistally th ro u g h b o th teeth. T h e re su ltin g t i l t is essentially the same as the t i l t o f u n sp linted teeth. T h e re is, o f course, the m echanical advantage o f h a v in g the stra in shared by tw o te e th ; how ever, the u n h e a lth y d is trib u tio n o f forces a p ica lly and c e rv ic a lly s till exists and there is n o t the m echanical u n ifo rm ity o f stress dis trib u tio n fo u n d in the s p lin t’s resistance to m esiodistal tiltin g . T h u s the s p lin tin g e ffect is least in its resistance to bucco lin g u a l loads. T h is m ay be counteracted to some e xtent by a p a rtia l den tu re w ith a rig id b a r w h ic h w o u ld p it the le ft and rig h t splints against each other. B U C C O L IN G U A L D IA M E T E R O F T E E T H
I n o rd e r to enhance th e s p lin t’s re d u ctio n o f occlusal tra u m a in th e b u cco lin g u a l d ire c tio n o th e r technics fo r the a lle v ia tio n o f tra u m a tic occlusion should be u tilize d . T h e s p lin t restorations should be n a rro w b u cc o lin g u a lly in o rd e r to reduce the to rq u e re su ltin g fro m occlusal forces
.404 • THE JO U R N A L OF TH E A M E R IC A N DENTAL A S S O C IA T IO N
P
a distinct advantage over splinting teeth in a straight line. R E S IS T A N C E T O R O T A T IO N A B O U T T H E L O N G A X IS O F T H E T O O T H
Fig. 2 • P and L are labiolingual forces; 2 and 7 indicate axes
which fall outside the long axis of the tooth. Naturally, complete occlusal equilibra tion should always be instituted before splinting is undertaken. S P L IN T IN G A R O U N D T H E A R C H
Since occlusal forces are multidirectional (mesiodistal and buccolingual), an ideal splint would have to run not only mesiodistally but also buccolingually. Carrying the splint around the curve of the dental arch approaches this ideal of multidirec tional splinting, of having the occlusal stress applied in the direction of the splint rather than at a right angle to it. In Figure 2 labiolingual force P falling on the central incisor tends to rotate the splint labially about an axis (2) running labiolingually. Since the central incisor and cuspid are not in one labiolingual line the axis (2) cannot run through both teeth but is located between them. Thus simple individual tooth tilting is impossi ble and bodily movement of the roots results. The same analysis can be applied to labiolingual force L which tends to produce bodily movement by rotating the splint around the dotted line 1 as the ful crum. Thus splinting around the arch has
In certain periodontal conditions teeth may drift, elongate or rotate. After the teeth are realigned in the dental arch they may require splinting because o f the di minished periodontal support. When the pathologic force causes rotation, as, for example, the rotation o f the lateral in cisor away from the central incisor as shown in Figure 3, the tooth may tend to move out again after realignment. The rotation may be considered analogous to a door swinging open. When it is closed it would be locked at the side which had opened the most and not near the hinges. Likewise, the rotated tooth, after realign ment, is “ locked” by splinting to the tooth from which it moved. In Figure 3 this would be the central incisor. If this sup port were considered inadequate because the central incisor was weak, then the cuspid might be included in the splint for added support just as a door may be immobilized by bolting it on both sides. I f the lateral incisor were splinted to the cuspid alone, it would be analogous to placing the door lock near the hinges. This lock could easily be forced. Figure 4 shows a rotated tooth which was realigned and erroneously splinted to the cuspid with three-quarter crowns soldered to gether. The tooth rotated out again. The rule is: a rotated tooth, which is realigned and requires splinting, should be splinted to the tooth from which it has moved most; for greatest support it may be splinted to the teeth on both sides of it. D IS T A N C E A N D T H E S P L IN T IN G E F F E C T
The effectiveness of the splinting action in a mesiodistal direction results from the buccolingual direction o f the axis o f ro tation, which obviously cannot run through both teeth simultaneously and
S IM R IN G . . . V O LU M E 45, OCTOBER 1952 • 405
therefore cannot p e rm it in d iv id u a l t i l t in g o f each to o th , b u t involves u n ifo rm m ovem ent o f b o th teeth. W hen the teeth are fu rth e r ap a rt, th e arc o f this m ove m e n t increases and induces a m ore n e a rly v e rtic a l resistance w h ic h is desirable. T h e fa rth e r a p a rt th e teeth are, however, the w eaker the b u cco lin g u a l s p lin tin g effect is because a s lig h t t i l t in one to o th w ill p e rm it a large m ovem ent in the o th e r as i f one to o th were ro ta tin g about the o th e r as a d ista n t fu lc ru m . T h u s the u n ify in g o r s p lin tin g a ctio n dim inishes as a w id e r la titu d e o f in d epe nden t to o th m ovem ent is p e rm itte d by d ista n t abutm ents. T h e re fo re w hen three o r m ore m issing posterior teeth are replaced, the s p lin tin g effect m ust be increased by in c lu d in g at least three abutm ents w hen opposed by the n a tu ra l d e n titio n o r a sta tio n a ry bridge (F ig . 5 ).
R IG ID IT Y A N D T H E S P L IN T IN G E F F E C T
“ R estorations re p la cin g three o r m ore missing p o ste rio r teeth and e m p lo yin g o n ly tw o abutm ents m ay be considered w hen the opposing d e n tu re is a tissueborne rem ovable a p p lia n ce .” 3 I n th is case the opposing d e n titio n being m ore y ie ld ing, the forces o f occlusion are lo w and th erefore considerable s p lin tin g effect is unnecessary. F u rth e rm o re , the u n y ie ld in g rig id ity o f the s p lin t m a y be dele terious to the rid g e u n d e rly in g the re m ovable denture. T h u s th e decreased m o b ility o f the sp linted to o th m a y cause some d ifficu ltie s. T h e g reater rig id ity o f a s p lin t m a y occa sionally w reak havoc on a weakened op3. The c o n s tru c tio n o f fixed b rid g e s . Led e rle news le tte r. New Y o rk, Led erle L a b o ra to rie s D ivision, A m e r i can C y a n a m id C o ., 1951.
Fig. 3 • A b o v e : A lateral incisor which has rotated away from central incisor because of perio dontal disease. Below le ft: A fter lateral incisor is realigned, it may require splinting to central incisor to prevent it from drifting out again , just as a door must be locked at the part which has rotated most. Below right: For greater stabilization, the splint may include cuspid as well as lateral and central incisors. This is analogous to barring a door on both sides in addition to locking
406 • THE J O U R N A L O F TH E A M E R IC A N DENTAL A S S O C IA T IO N
Fig. 4 • A bove left: Lateral incisor which drifted away from central incisor. A bove right: Lateral incisor realigned with stainless steel ligatures. B elow : T ooth splinted to cuspid with soldered three-quarter crowns. Slight rotation of lateral incisor is apparent
posing to o th . F o r exam ple, a second m o la r m ay be rig id ly sp linted to a firs t m o la r to preve nt extrusio n and fo o d im p a c tio n w here the opposing second m o la r is miss ing. I f the opposing firs t m o la r is a lone to o th th a t m ust also su p p o rt the load o f a p a rtia l d e nture atta ch m e n t, occlusal tra u m a m ay re su lt u p o n th is weakened firs t m o la r. I t is w iser to e xtra ct th e sec ond m o la r i f i t interferes in any w a y o r to e xtra ct th e a d ja cen t firs t m o la r i f its prognosis is d o u b tfu l and replace i t w ith a fixe d bridge. T H E PR A C T IC E O F S P L IN T IN G
Non-shrinking Waxed Silk Ligature
4-6 • A double loop is tie d around the firs t
to o th and secured w ith a surgeon’s knot. E ach re m a in in g to o th , in tu rn , is tied w ith a single loop secured a t the ne xt in te rp ro x im a l space w ith a nother sur geon’s kn o t. O n the p ro x im a l surfaces the lig a tu re is placed so th a t i t is g in g iv a l to th e c o n ta ct p o in t (w idest m esiodistal d ia m e te r ); la b ia lly and lin g u a lly i t is in cisa l to th e c in g u lu m (w id e st la b io lin gual d ia m e te r ); thus the lig a tu re is
4. M ille r , S. C . Textbook o f p e rio d o n tia , e d . 3. P h ila d e lp h ia , B lakiston C o ., 1950, ch. 17. 5. H irs c h fe ld , L. The use o f w ire and s ilk lig a tu re s . J .A .D .A . 41:647 (D e c .) 1950. 6. S o rrin , _S. The use o f fix e d and re m o v a b le splints in the p ra c tic e o f p e rio d o n tia . A m . J. O rth o d o n t. & O ra l S urg. (O ra l Surg. Sec.) 31:354 (June) 1945.
S IM R IN G . . . V O L U M E 45, OCTOBER 1952 • 407
Fig. 5 • Fixed bridge replacing second bicuspid and first and second molars attached with cast gold crowns to cuspid, first bicuspid and third molar (Sept. 27, 1947)
Showing im proved health of alveolar bone (D ec. 30, 1950)
secure. I t cannot slip g in g iv a lly o r in cisally. I n o rde r to a vo id tra c tio n and possible d riftin g o f the teeth w here the teeth do n o t contact one another, a su fficie n t n u m ber o f knots m ay be tie d in te rp ro x im a lly u n til the next a djacent to o th is reached. Instead o f m u ltip le knots, a single k n o t m ay be tie d adja cent to each to o th and the in te rp ro x im a l lig a tu re m a y be em bedded in a sm all piece o f q u ic k -c u rin g a crylic resin a p p lie d a fte r the lig a tu re has been com pletely tied. T h is w ill also add to the strength and security o f the s p lin t w h ile s im p lify in g its a p p lic a tio n . Because o f the absorption o f fo o d debris and saliva, the lig a tu re tends to become
fo u le d and m ay need to be changed every tw o weeks o r m ore ofte n . T h is absorption can be decreased and the d u ra b ility in creased by firs t p a in tin g the d rie d to o th surfaces w ith sandarac va rn ish and then, a fte r ty in g the s p lin t, a p p ly in g a second coat o f varnish. Because a ll splints w h ic h the p a tie n t cannot rem ove m ay in te rfe re w ith ade quate to o th b ru sh in g , an advisable o ra l sa n ita tio n a d ju n c t is a device fo r fo rc e fu l w a te r irrig a tio n o f the m o u th , as sug gested by M ille r ,7 w h ic h m a y be attached to th e fa u c e t; fo r exam ple, a com m ercial shower attachm ent. W h ile silk ligatures are ra p id ly and easily a p plied, th e ir d u ra b ility and rig id ity are low . F u rth e rm o re lig a tio n is generally lim ite d to the six a n te rio r teeth because o f th e ir anatom y. P osteriorly, the anatom y o f the teeth perm its the lig a -
7. M ille r , S. C ., O ra l d iagnosis and tre a tm e n t p la n n ing, ed. I. P h ila d e lp h ia , Blakiston C o., 1936, p. 256.
408 • TH E J O U R N A L O F THE A M E R IC A N DENTAL A S S O C IA T IO N
5. S tabilize teeth u n til a m ore p e rm a ne n t type o f s p lin t is constructed. 6. S tabilize teeth w ith questionable prognosis u n til the results o f tre a tm e n t in d ica te w h e th e r the to o th m ay be re tained. 7. S tabilize, fo llo w in g th e ir re p o sitio n ing, tee th w h ic h had m ig ra te d , ro ta te d o r e xtru d e d as a result o f p e rio d o n ta l dis ease. These m ay also be considered fo r a ll te m p o ra ry splints. T h e type chosen de pends on the fo llo w in g fa c to rs : s im p lic ity o f a p p lic a tio n , d u ra b ility re q u ire d , rig id ity re q u ire d , lo ca tio n, esthetics, o ra l sanitation and p a tie n t cooperation.
Wire Ligature*'6'6'10
Fig. 6 • A b o v e : A rch or circum ferential wire, 0.020 inches diameter, secured with interden tal wires o f finer gage, 0.007 inches diameter. Below : A rch or circum ferential wire consisting of tw o strands of 0.010 inches stainless steel ligature
tu re to slip g in g iv a lly so th a t the s p lin t is loosened and m ay irrita te the gingiva. L ig a tu re m ay be used, how ever, fo r s p lin t in g posterior teeth w hen the necks o f the teeth are constricted o r the roots are heavy.
Indications
• S ilk is va lu a ble as a s p lin t w he n i t is requ ire d o n ly fo r a m a tte r o f weeks in o rd e r to : 1. S tabilize a to o th w ith acute perice m en titis. 2. S tabilize a to o th loosened by a blow . 3. S tabilize loose teeth in o rd e r to a void undue in ju r y o r d isco m fo rt to th e m caused b y in stru m e n ta tio n , p e rio d o n ta l surgery o r g rin d in g to relieve occlusal pressure. 4. S tabilize teeth d u rin g p e rio d o n ta l tre a tm e n t in o rd e r to pro m o te h e a lin g and possible rca tta c h m e n t o f the su p p o rt in g tissues.
• W ire lig a tu re , lik e silk lig a tu re , is lim ite d generally to the a n te rio r teeth fo r ana to m ic reasons. I t is stronger th a n silk b u t takes lo n g er to apply. I t is m ore du ra b le th a n silk and m ay even be retained fo r several years o f tre a tm e n t and observation. W ire lig a tu re is n o t esthetic, however, and w h ile i t does n o t absorb flu id s i t tends to catch food p a rticle s and is d iffic u lt to keep clean. A c c id e n ta l breakage o r u n tw is tin g o f the w ire m ay expose sharp edges w h ic h i r r i ta te the lips, cheeks, tongue and gin g iva . V a rio u s types and gages o f w ire have been suggested in the lite ra tu re . A dead soft stainless steel lig a tu re e ith e r 0.020 inches in d ia m e te r (F ig . 6, above) is satisfactory, o r w here greater fle x ib ility and ease o f a p p lic a tio n are needed, tw o strands o f 0.010 inches as the a rch w ire (F ig . 6, b e lo w ). In te rd e n ta l w ires are 0.007 inches in diam eter. T h e arch w ire is looped aro u n d a ll the teeth to be in cluded in the sp lin t, ro u g h ly adapted to the teeth, and the ends are tw iste d to ge th e r lig h tly . L ik e silk lig a tu re , the steel is k e p t g in g iv a lly to th e con ta ct p o in t
8. Rhein, M . L. S p lin tin g loosened te e th in pyorrhea a lv e o la ris . D. Cosmos 45:369 (M a y ) 1903. 9. Sm ith, R. C o n s tru c tio n o f a s p lin t in p e rio d o n ta l tre a tm e n t. D. D igest 47:118 (M a rc h ) 1941. 10. Barkann, L. The case fo r m e ta l lig a tu re s in p e rio d o n tia . J . 2nd D ist. D. Soc. (N .Y .) 31:341 (D e c .) 1945.
S1MR1NG . . . V O L U M E 45, OCTOBER 1952 • 409
and in cisally to the cin g u lu m . Strands o f the th in n e r gage w ire , about one and a h a lf inches long, are bent like h a irp in s w ith one a rm lo nger th a n the other. Each in te rd e n ta l “ h a irp in ” is inserted fro m the lin g u a l side w ith the lo n g er a rm g in g iv a l to the arch w ires and the shorter a rm between the a rch wires and the con ta c t p o in t. U s in g a hem ostat o r fine beaked pliers, each in te rd e n ta l w ire is tw isted tig h t clockwise. O v e rtw is tin g w ill cause breakage. T h e ends o f a ll the wires are then cut, le a vin g about 3 o r 4 m m . o f the tw isted ends stickin g o u t. These are th e n curled a ro u n d the end o f a broken in s tru m e n t w ith an am algam plugger. T h e in s tru m e n t is w ith d ra w n and the little loop o f w ire is then tucked, w ith the p lugger, in to the in te rp ro x im a l em brasure to a void soft tissue irrita tio n . S hould the s p lin t become loose at any tim e , these lit tle w ire loops m ay easily be tightened. T h e arch w ire fre q u e n tly slips in cisa lly o ff the d ista l aspect o f the cuspids be cause o f an open contact o r because the to o th is conical in shape. T h is slipping m ay be prevented by a cervica l re ta in in g w ire loop as described by H irs c h fe ld .5 A piece o f th in gage w ire is placed around the neck o f the cuspid o r around the neck o f the firs t bicuspid (F ig . 6, b e lo w ), i f the cuspid is too conica l to re ta in this w ire , and d ra w n tig h t w ith ab o u t three twists. O ne strand is n o w placed u n der the arch w ire on the d istal aspect o f the cuspid and the o th e r strand o f the re ta in in g loop is placed over the arch w ire and then b o th strands are tw isted together enclosing the arch w ire . T h e tw isted end o f the re ta in in g w ire is c u t short and cu rle d away in te rp ro x im a lly . T h e ta u t w ires m ay tend to d ra w the teeth together in to th e smallest possible arc. T h e re fo re , w here the teeth are n o t in conta ct m esiodistally, the in te rd e n ta l space m ay be taken u p by tw is tin g the arch w ires together to brid g e the space or, as w ith the silk ligatures, a sm all piece o f q u ic k -c u rin g a c ry lic resin can be
Fig. 7 • Extradental acrylic resin splint ap plied directly betw een the teeth while toothcolored acrylic resin is soft
placed to b rid g e the space between tw o teeth, e n veloping the a rch wires. T h e w ire s p lin t’ s p o o r esthetics and its possible ir r ita tio n to the lip m ay be over come by a p p ly in g a th in layer o f to o th colored q u ic k -c u rin g a c ry lic over the la b ia l a rch w ire a fte r the s p lin t is com pleted. T h e shadow o f the wires m ay be obscured by firs t p a in tin g th e m w ith an o p a cifie r paste m ade o f lig h t ye llo w zinc oxyphosphate cem ent p o w d er plus a fe w drops o f the a c ry lic m onom er, and then a p p ly in g the fre sh ly m ixe d a c ry lic resin. T h e se lf-curin g a crylic resins m a y also be used so as to p e rm it the use o f w ire lig a tu re splints p osteriorly. A fte r the ap p lic a tio n o f the d o u ble-strand a rch o r c irc u m fe re n tia l w ire , i t is secured in place w ith sm all plugs o f the self-curing a crylic resin placed in each in te rp ro x im a l embrasure, buccal as w e ll as lin g u a l, engaging and enclosing the a rch w ire. O nce these plugs set they w ill prevent occlusal o r g in g iv a l m ovem ent o f the arch wires. I f there is a tendency fo r the arch w ire to slip g in g iv a lly d u rin g its a p p lic a tio n i t can be secured w ith sepa rate strands o f w ire w h ic h ru n fro m buccal to lin g u a l across the occlusal surface. B oth buccal and lin g u a l strands o f the arch w ire are engaged and are d ra w n ta u t. These accessory b u cco lin g u a l wires m ay be c u t o ff a fte r the a rch w ire has been secured w ith the p ro x im a l a crylic plugs.
Extradental Plastic
• A m e th o d recently advocated by S o rrin can be used where there is adequate space between the lo w e r incisors (F ig . 7 ). T o o th -c o lo re d q u ick-
410 • T h e J O U R N A L O F TH E A M E R IC A N DENTAL A S S O C IA T IO N
Fig. 8 • L e ft: Stainless steel wire, 21 gage, adapted to stone cast. Self curing acrylic resin is processed over this. R ight: C om pleted surgical apron-splint in place in patient’ s mouth
c u rin g a c ry lic resin is freshly m ixe d and fo rm e d in to a s trip w h ic h is placed lin g u a lly and pushed la b ia lly th ro u g h the in te rd e n ta l spaces. A la b ia l core o f im pression com po u n d m ig h t be made in i tia lly to stabilize the teeth d u rin g the procedure. U n fo rtu n a te ly , this esthetic, stable, and sim p ly a p p lie d s p lin t can be rem oved o n ly by g rin d in g i t off.
Intradental Plastic
• O b in and A rv in s 11 advocate a h ig h ly esthetic, fa irly stable m eth od o f te m p o ra ry s p lin tin g w h ic h is o f value w here a m ore perm a n en t restora tio n w ill be in d ic a te d i f the teeth can be retained. A fte r the teeth are ligated w ith d e n ta l floss fo r s ta b ility, a plaster o r com pound core is m ade and th e n an u n d e rc u t groove is prepared in th e teeth (lin g u a lly in an te rio r te e th ; occlusally in posterior teeth) and this is packed w ith self-curing resin w h ic h is he ld in place by the core u n til i t has set. A c c o rd in g to O b in and A rv in s , superior m a rg in a l a d a p ta tio n can be obtained by m a k in g in d iv id u a l m esiolinguodistal res tora tio ns in se lf-c u rin g a crylic resin fo r each to o th and th e n u n itin g th e m a ll w ith m ore o f the resin.
Soldered Bands 6
• Each to o th is banded and th e in d iv id u a l bands are soldered together and cem ented to place. T h is is used fre q u e n tly to p ro v id e the resistant fo rce re q u ire d fo r m o vin g teeth o rth o d o n tic a lly . I t is uncsthetic b u t provides good sta b iliz a tio n , a lth o u g h bands do occasionally loosen because o f occlusal pressure. E xc e lle n t c o n to u rin g is essential to a vo id g in g iv a l irrita tio n and dental caries.
Removable Cast M etal
6,12 • A c o n tin u ous cast clasp s p lin t, as advocated o rig i n a lly by M ille r ,4 w h ic h encircles the teeth a t th e ir heights o f c o n to u r b u cca lly and lin g u a lly can be cast in go ld o r chrom eco b a lt a llo y and affords an excellent te m p o ra ry s p lin t. In te rfe re n ce w ith occlusion m ust be avoided. T h e y are m ore rig id th a n lig a tu re s a n d m a y be rem oved by the p a tie n t fo r cleaning. E sthetically, how ever, they are poor. T h e continuous clasp s p lin t is fr e q u e n tly used as p a rt o f a rem ovable p a r11. O b in , J. N ., and A rvins, A . N. The use o f selfc u rin q resin s p lin ts f o r th e te m p o ra ry s ta b iliz a tio n o f m o b ile te e th due to p e rio d o n ta l in v o lv e m e n t. J .A .D .A . 42:320 (M a rc h ) 1951. 12. Schweitzer, J . M . O ra l re h a b ilita tio n . St. Louis, C . V. M osby C o ., 1951.
SI MRI NO . . . V O L U M E 45, OCTO BER 1952 • 411
tia l d e n ture so th a t the s p lin tin g effect o f m u ltip le abutm ents m ay be u tiliz e d fo r the su p p o rt o f a rtific ia l teeth and, occasionally, to supp ort some w eak n a tu ra l teeth at the same tim e. T h e s p lin t in g effe ct m ay be enhanced by in c o r p o ra tin g in to the appliance, attachm ents w h ic h fit rig id ly in to slots in inlays o r crow ns on the teeth. Precision a tta c h ments o r precision lugs resting in p re c i sion lu g seats are thus o f great value. In o rd e r to a tta in o p tim u m efficiency in the rem ovable d e n tu re -sp lin t by ca rry in g the s p lin tin g effect arou nd the arch, a rig id b a r is essential.
Removable Plastic Splints 4' 6,13
• T h e es th e tic disadvantage o f th e cast m e ta l re m ovable s p lin t can be overcom e b y the use o f m e th y l m etha cryla te resin. T h is sim ple, inexpensive, esthetic s p lin t is w eaker and b u lk ie r, how ever, th a n the a ll-m e ta l continuous clasp sp lin t. O n a cast o f the p a tie n t’s m o u th , a 21 gage stainless steel w ire is contoured around the teeth above the w idest p o rtio n o f the to o th . I n m a k in g an a n te rio r s p lin t the w ire w o u ld be lim ite d to the lin g u a l sur faces and the d ista l h a lf o f the la b ia l surfaces o f the cuspids. T ra n sp a re n t a c ry lic resin is th e n processed la b ia lly and lin g u a lly w ith the w ire embedded at
Fig. 9 • U pper roentgenogram s made before periodontal pocket treatm ent. G utta-percha points indicate depth of pockets. L ow er left pictu re was made 10 weeks later; low er right figure was made seven months later
a ll p o in ts except a t the distal ends o f the s p lin t w here i t passes in te rp ro x im a lly . T h u s the s p lin t can be rem oved by the p a tie n t fo r cleaning. O cclusion m u st be checked c a re fu lly. T h e s p lin t should be constructed so th a t i t does n o t engage deep undercuts on the teeth since re peated w ith d ra w a l and in sertion by the p a tie n t m ig h t prove tra u m a tic and the salutary s p lin tin g effect w o u ld be negated. S e lf-c u rin g a c ry lic resin also can be used. I t is n e ith e r as strong n o r as dense as the re g u la r heat-cured m e th yl m e th acrylate resin. F ig u re 8 shows w ire w h ic h has been adapted a ro u n d the teeth o f the p a tie n t’s study cast. T h e a c ry lic resin was th e n placed over it. T h e resin was ex tended over the g in g iva to fo rm a sur g ic a l apron. I n this instance the second b icu sp id was so m o b ile th a t i t co u ld be depressed in its socket. T h e d e p th o f the pockets m esially and lin g u a lly are shown in F ig u re 9, above. A fte r th o ro u g h con servative p e rio d o n ta l tre a tm e n t, a fla p o p e ra tio n was p e rfo rm e d lin g u a lly in the bicuspid firs t m o la r region. T h e fla p was he ld in place by the surgical a p ro n -s p lin t w ith o u t the interference o f sutures. T h u s b o th d e n ta l and p e rio d o n ta l tissues were
13. S o rrin, S. A c r y lic s plints fo r loose te e th . P e rio d o n tia Bull., Feb. 27, 1942.
N .Y .U .
412 • THE J O U R N A L O F THE A M E R IC A N DENTAL A S S O C IA T IO N
immobilized. After six weeks the gingival apron portion was cut off and the patient used the .appliance for an additional month as a removable splint. T h e present excellent state of periodontal healing is indicated in Figure 9, below. At this time the lingual gingival sulcus was only 1 mm. deep and could not retain a gutta percha point. Mobility was only slightly greater than normal. Interlocking Inlays • An interlocking inlay-splint consists of an inlay with an extension that fits snugly into a slot in an inlay on another tooth. The interlocking inlay-splint is effective to the extent that the two inlays are rigidly connected. Thus the male part should be long and both parts should fit tightly. The lateral splint ing effect is diminished if lateral play is permitted between the inlays. The male restoration must cover the entire occlusal surface of its tooth since the male inlay is held in place by the female inlay and an uncovered occlusal area would permit the tooth to be depressed in its socket and be detached from the male inlay. Resistance to vertical occlusal pressure is poor in the female section o f this splint. Thus the interlocking inlay provides in complete splinting. Its only indication might be the rare case in which parallel ism prohibits the use of a soldered joint between restorations. Stationary Splints*'*’14 • The stationary splint composed of several three-quarter or full cast crowns or other type of full coverage soldered together is the most durable and efficient splint. Since the splint and teeth are relatively unyielding, considerable internal strain develops within the individual abutment restorations. Smyd15 has shown that a simple M O or M O D inlay may spread as a result of these tensions. The buccal and lingual “ bands” of crowns prevent this spread and avoid possible leaks, loos ening of the splint and caries under the restorations.
Furthermore, full occlusal coverage is essential. Since the splint is unyielding and is rigidly attached to several teeth, it may separate from one of the teeth if occlusal pressure, falling on the tooth surface and not on the splint, depresses that tooth slightly within its alveolar socket and away from the splint. For these reasons, cast crowns are advo cated for stationary splints posteriorly and ordinary inlays are contraindicated. Three-quarter crowns may be used in a mouth that is caries resistant, where the teeth to be splinted “ present good vertical length since the retention of this attach ment is dependent on long grooves. Where short teeth are to be splinted, full crowns, with or without acrylic veneers, are indicated.” 16 For anterior teeth, threequarter crowns or thimbles and porcelain jackets or, where the occlusion is heavy, full castings with porcelain or acrylic resin facings may be employed. The soldered joint between the crowns must be rigid and must be placed close to the occlusal area so the gingival tissue is not impinged on and so adequate oral sanitation is possible. The soldered joint must be fully rounded occlusally and gingivally; narrow capillary spaces which would trap food and saliva must be avoided.17 Diligent home care by the patient is essential where splinting is utilized. The use of a rubber interdental stimulator is indicated where there is gingival reces sion interdentally. A modified Stillman’s method of toothbrushing should be sup plemented by the modified Charter’ s method o f toothbrushing in order to cleanse and stimulate the interdental re-
14. Kabnîck, H . H ., and Elson, M . Prosthetic a id em p lo y in g fix e d b rid g e s a n d splints in p e r io d o n ta lly in v o lv e d te e th . A lp h a O m eg an 44:85 (S e p t.) 1950. 15. Smyd, E. S. D ental e n g in e e rin g as a p p lie d to in la y and b rid g e fa b ric a tio n . New Y ork J . Den. 21:161 ( A p r il) 1951. 16. M ü le r, S. C . Textbook o f p e rio d o n tia . P h ila d e l p hia, B lakiston C o ., 1938, p. 471. 17. G o ttlie b , B., and O rb a n , B. Z ah nfleisch ent zündung und Zah nlocke rung . Berlin, Berlinische Verlagsansta lt, 1933, p. 280.
S IM R IN G . . . V O LU M E 45, OCTOBER 1952 • 413
Fig. 10 • Precocious advanced alveolar atrophy with pockets involving trifurcations o f upper molars and bifurcation of low er left first molar in 23 year old man
gions adequately. A n excellent device fo r o ra l hygiene is th e p a tie n t’ s use o f w a te r irrig a tio n as p re vio u sly suggested. R egu la r professional denta l p ro p h yla xis three times a year is essential. Because o f the d iffic u lty o f p ro p e r o ra l sa n ita tion and d e n ta l in s tru m e n ta tio n in the second and th ir d m o la r in te rd e n ta l region, s p lin tin g is generally avoided be tween these teeth. Esthetics occasionally dem and the use o f a s p lin t composed o f in d iv id u a l porce la in ja cke t crow ns cem ented over g oldth im b le copings soldered together. Cleansa b ility , g in g iv a l stim u la tio n , and freedom fro m g in g iv a l ir r ita tio n are m ore d iffic u lt to a tta in w ith p o rce la in jackets th a n w ith g old cast crow ns faced w ith a crylic resin o r porcelain. W here p o rce la in ja c k e t s p lin tin g is used, some type o f te m p o ra ry s p lin tin g is in d ic a te d d u rin g the in te rv a l between to o th p re p a ra tio n and in sertion o f the com pleted s p lin t. I f te m p o ra ry clear a crylic resin cro w n form s are used, these m ay be jo in e d w ith a lit tle o f the selfc u rin g a c ry lic resin placed at the lin g u o in te rp ro x im a l points. T h is type o f sp lin t can also be used w here teeth are prepared fo r th re e -q u a rte r crowns. A n alternate procedure consists o f ta k in g an im pression w ith alg in a te im pres
sion m a te ria l before the restorative p re p arations are m ade and setting this aside u n til the p reparations are com pleted. T h e n s e lf-cu rin g a c ry lic resin is m ixe d and placed in to the impression in those teeth th a t have been prepared. T h e im pression is then re-inserted, h e ld in place fo r three to five m inutes, and w ith d ra w n before the resin has become com pletely ha rd . I t is p e rm itte d to bench-harden. T h e n i t is rem oved fro m the im pression, trim m e d , polished, and inserted w ith a te m p o ra ry cem ent such as zinc o xid e and eugenol. S im ila r te m p o ra ry crow ns fo r ad ja cen t teeth can be prepared and fused to the firs t ones i f a d d itio n a l teeth are p repared a t a la te r tim e. S ta tio n a ry splints are in d ic a te d w here the m a x im u m s p lin tin g e ffect is essen tia l in o rd e r to re ta in teeth because o f the large a m o u n t o f bone loss o r because the teeth have a tendency to d r ift. A l th o u g h s p lin tin g w ill a id tee th in w ith standing a n o rm a l fu n c tio n a l occlusal load w h ic h m ig h t otherwise prove tra u m a tic to them , C oolidge and H in e 18 state: “ T h e re m ust be a t least o n e -th ird o f the ro o t surrounded by tissue th a t gives
18. C o o lid g e , E. D ., and H ine, M . K. P e rio d o n tia ; c lin ic a l p a th o lo g y and tre a tm e n t o f the p e rio d o n ta l tis sues. P h ila d e lp h ia , Lea & F e b ig e r, 1951, p . 209.
414 • TH E J O U R N A L O F THE A M E R IC A N D ENTAL A S S O C IA T IO N
Fig. 11 • H ealing o f periodontal tissues 18 months later
clinical evidence of health and firmness.” Thus pathosis must be eliminated and a careful diagnosis made before stationary splinting is undertaken. The cast crown stationary splint also may be used for teeth that must withstand an occlusal load greater than normal. This is accomplished by using multiple abut ments for fixed and removable prostheses. According to Kabnick and Elson,14 “ Bone support for two-thirds of the root length is the minimum amount necessary for a single abutment tooth.” Therefore mul tiple abutments must be utilized in many cases where periodontal disease has been present. The excellent healing of the bone which follows such treatment is shown in Figures 10 and 11. Three of the first m o lars had clinical involvement of the root bifurcation. They were extracted and, following conservative periodontal treat ment, were replaced with three fixed bridge-splints attached to both bicuspids and the second molar. The periodontal improvement is apparent in Figure 11. When collapse of the maxillomandibu lar vertical dimension has occurred be cause of extreme wear or drifting of the teeth, the restoration of the lost vertical dimension to its normal height ( “ bite-raising” ) frequently increases the periodontal strain by increasing the extra-
alveolar lever arms of the teeth. Sta tionary splinting is indicated to prevent the periodontal disease that may be the aftermath of increasing the height of the crowns of the teeth. Thus splinting is indicated where the traumatic effects of occlusion are intense and the stimulating physiologic action of occlusal force needs to be improved. It follows that wherever splinting is indi cated, thorough occlusal equilibration is indicated first. Furthermore, the restora tions involved in the splint itself must fulfill the requirements o f occlusal equi libration and harmony with the patient’ s dentition and temporomandibular joint function. S U M M A R Y A N D C O N C L U S IO N
Splints are of value in supporting loose teeth, weakened teeth and strained abut ment teeth. Splints divide occlusal strain over several teeth and direct it physio logically. Although the most effective splinting is attainable only with cast crowns soldered together, there are many indications for the various types of tem porary splints. Splinting may be consid ered to be an adjunct in the treatment and prevention of occlusal trauma.
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