Articulator adjustments using the transfer vise Michael Tradowsky, D.D.S., Dr.Med.Dent.* Case Western Reserve University, School of Dentistry, Cleveland, Ohio
adjustable articulators so that individual articulator settings can be obtained. Among the many ways articulators have been adjusted to jaw movements of individual patients, checkbite 1. 2 and pantographic tracing a techniques have predominated. Checkbite techniques serve edentulous patients, and the pantographic tracing technique is used with patients requiring repositioning of the mandible and reconstruction of the occlusal surfaces of the teeth. In addition to patients needing complete dentures or occlusal reconstruction, there is a large group of patients needing posterior fixed restorations. These restorations too often are made where the individual characteristics of the patient's temporomandibular joints are ignored. The dentist compensates for this omission by "grinding-in" the restorations. This is costly and time-consuming," and where the grindingin procedure is incomplete occlusal interferences may initiate periodontal breakdown?' 5 The transfer vise technique is helpful in the treatment of these patients, and it may serve as an adjunct to existing methods.
frictionally gripped between the respective pairs of jaws and fixed in a given position. Besides the transfer vise the clutch handles carry a twin Gothi c arch (needle point) tracing mechanism (Fig. 2, A, [j] to [/]). The tracing tables (j) are attached to the lower handle (d), and the styli (k) are attached to the upper handle (c) by the stylus bar (l). The handles are attached to acrylic resin clutches (Fig. 2, B, [a]). Embedded on the lingual side of the clutches are the upper and lower metal central bearing plates ([b] and [c]). The lower central bearing plate carries the central bearing screw (d), which rides on the upper central bearing plate in the usual manner. After the patient has traced twin Gothic arches the dentist can see the location of centric relation and lock the transfer vise in this position for remounting of the lower cast. Also the jaw can be moved into various measurable excursions and the transfer vise can be locked into these positions. Each eccentric jaw relation and protrusive, right, and left lateral position can be transferred to mounted casts for the adjustment of the articulator. The combination of the tracing assembly and the transfer vise is called the "Minigraph System. ''*~
DESCRIPTION OF THE TRANSFER VISE
METHOD
The transfer vise (Fig. 1) is a mechanism which allows the instant fixation of the jaw in centric relation or any eccentric position. Two transverse bars(Fig. 2, A, [a] and [b]) are attached to upper and lower clutch handles (c) and (d). The spherical end portions (e) and (f) of these transverse bars are engaged between pairs of curved vise jaws (g). These vise jaws are retained by screws (h) and (i) for universal movement. Upon tightening of the knurled thumbscrew (i) the pair of spheres (e) and (f) are
Although the following method describes the transfer vise technique as used with the Simulator articulator,* it also can be used for setting other adjustable articulators.
This
article describes a new instrument, the
transfer vise,'~ which is used to transfer jaw positions to
"*Associate Professor and Chairman, Department of Fixed Prosthodontics. tJ. Aderer, Inc., Long Island City, N. Y.
THE JOURNALOF PROSTHETICDENTISTRY
Preliminary procedures Obtain a set of accurate diagnostic casts. The upper cast should be mounted to three reference points: the right and left hinge axis points and an anterior reference point. The hinge axis points can either be accurately determined 7 or estimated. 8 Usually the estimated hinge axis points are used with *J. Aderer, Inc., Long Island City, N. Y
47
TRADOWSKY
Fig. 1. The transfer vise and Minigraph have been attached to the patient's teeth through clutches. k
k
|
i!
Fig. 3. Anterior reference point jig positioned on patient's nose for marking the anterior reference point. h @--
tJ
(1
g
| Fig. 2. A, the transfer vise consisting of the transverse bars (a) and (b), the spherical end portions (e) and (f), and the pairs of curved vise jaws (g), which are retained by the screws (h) and (i). The transfer vise is attached to a Minigraph consisting of upper and lower clutch handles (c) and (d), the tracing tables 0), and the styli (k), which are retained by the stylus bar (l). When the knurled thumb screws (i) are loosened the patient can move the jaw freely in excursions and trace twin Gothic arch tracings. When the knurled thumb screws are tightened the vise and the clutches are fixed in a given position. The jaw relation can then be transferred to mounted casts for articulator adjustments. B, midsagittal crossection of the vise, tracing mechanism, and clutches. Acrylic resin (a) holds the upper and lower bearing plates (b) and (c). The lower bearing plate carries a central bearing screw (d).
the transfer Vise technique. For the determination of the anterior reference point an anterior reference point jig is used (Fig. 3). This jig is a perpendicular plastic angle with a long and a short leg. T h e long leg has an engraved midline with a hole on it 20 m m
48
away from the angle. T h e anterior reference point is marked through the hole after the midline on the jig is superimposed on the midline of the patient's face. T h e angle rests gently against the tip of the nose. T h e advantage of the jig is that the dentist can locate the third reference point accurately at any time in the future. T h e lower cast is m o u n t e d by h a n d articulation or with a wax or a zinc oxide/eugenol centric relation registration. T h e incisal guide pin is set at 0. T h e precision of the m o u n t i n g of the lower cast at this point is not critical because the lower cast will be remounted using the transfer vise. This m o u n t i n g is used for making the clutches only. Fabrication of c l u t c h e s
The clutches are m a d e between appointments by a dental laboratory technician. From a m o n g the several ways in which clutches and transfers can be made, the following guidelines have been selected for their ease, speed, and accuracy of procedure: 1. Prepare the clutch former assembly (Fig. 4). It consists of the lower central bearing plate (a), the lower plastic spacer (b), the occlusal sheet (c), the upper plastic spacer (d), and the upper central bearing plate (e). T h e components are held together by the clutch assembly screw (f) and the nut (g). T h e plastic spacers are 0.04-inch-thick vinyl resin sheets having the same shape as the bearing plates. T h e y are slightly smaller so that a recess is created under the slanted sides and the short front of the bearing plates, providing space into which the acrylic resin of
JANUARY 1978
VOLUME 39
NUMBER 1
ARTICULATOR ADJUSTMENTS USING TRANSFER VISE
the clutches can engage. The occlusal sheet is 0.02inch-thick vinyl resin that extends approximately 5 m m beyond the facial surfaces of the upper teeth when placed between the dental arches. When the articulator is closed the sheet bends according to the occlusal curvature of the arches. Place the clutch assembly screw through the back hole of the lower central bearing plate, then through the lower plastic spacer, the occlusal sheet, the upper plastic spacer, and the upper bearing plate. Place the nut on the screw, center all components, and tighten the nut. 2. Place the clutch former assembly between the casts (Fig. 5) and adjust the handles on their spacer bar so that they touch the labial surfaces of the upper and lower anterior teeth while being held parallel to the occlusal plane. 3. On the lower bearing plate place beading wax into the slot and over the screw head (Fig. 6, A). Also run beading wax 2 m m inside of the margin of the bearing plate and onto the occlusal sheet to its posterior rim. The wax will prevent acrylic resin from running onto parts of the bearing plate that should stay exposed during clutch formation. On the upper bearing plate, as on the lower, cover the nut with beading wax and run beading wax 2 m m away from the margin out to the occlusal sheet to its posterior margin (Fig. 6, B). Make sure that the space between the wax walls on the occlusal sheet is wide enough to permit the wrench to engage the clutch assembly nut after the clutches have been formed. 4. Cover all surfaces below the height of contour on the upper and lower dental arches with Play Doh (Fig 7).* With a small spatula block out all of the undercuts between the teeth and fill in the lingual and palatal regions. The Play Doh should meet these surfaces of the teeth at a 90 degree angle. Using a plaster knife cut the Play Doh vertically, 3 m m from the facial surfaces. In the anterior region press the Play Doh out of the way to make room for the handles. 5. Coat the teeth with a foil substitute. 6. Place the clutch former assembly over the lower dental arch, pressing it down into the Play Doh. Close the articulator and press down until the occlusal sheet bends according to the occlusal pressure of the teeth. Project a vertical line from the upper anterior rim of the Play Doh onto the occlusal sheet and mark this line with a pen (Fig. 8). This line *Kenner Products, Cincinnati, Ohio.
THE JOURNAL OF PROSTHETIC DENTISTRY
g
|
\
I
d-\ m
I
Fig. 4. An exploded view of the clutch former assembly consisting of the lower central bearing plate (a), the lower plastic spacer (b), the occlusal sheet (c), the upper plastic spacer (d), the upper center bearing plate (e), the clutch assembly screw (/), and nut (g).
Fig. 5. The clutch former assembly has been placed between the casts and the handles have been adjusted according to the amount of horizontal overlap. will help to reposition the clutch former assembly when it is loaded with acrylic resin. 7. Open the articulator and remove the clutch former assembly. Where the margins of the bearing plates are imprinted into the Play Doh on the upper and lower arch, relieve 2 m m with a small wax spatula (Fig. 9). This will aid in locking the bearing plates into the acrylic resin. Readjust the blockedout regions on the lingual and palatal surfaces of the teeth if necessary.
49
TRADOWSKY
Fig. 6. A, on the lower bearing plate, areas which have to stay free from acrylic resin have been isolated with beading wax. B, wax on the upper bearing plate.
Fig. 7. Upper and lower casts blocked out below the height of contour with Play Doh. 8~ Mix enough cold-cure denture tray material for both clutches (the mix should be thin). A p p l y it over the upper and lower teeth with a tongue blade. Wipe the resin a r o u n d the u p p e r and lower bearing plates, making sure that the notches formed by the spacers are filled. Place the loaded clutch former assembly on the lower cast and close the articulator. Adjust the position of the clutch former assembly so that the mark on the occlusal sheet is lined up as it was previously. Incorporate the handles into the clutches by a d a p t i n g the acrylic resin a r o u n d them with a small wax spatula. Support the handles with Play D o h placed on the incisal guide table so that they stay parallel to the occlusal plane. Verify that the upper and lower acrylic resin clutches are not in contact and allow them to set. 9. After the resin has set remove the casts from the articulator. Unscrew the Allen screw from the u p p e r handle and dig through the wax to the clutch assembly nut and unscrew it. Separate the u p p e r and SO
Fig. 8. A vertical line is dropped from the anterior margin of the Play Doh onto the occlusal sheet. This marked line will help reposition the clutch former assembly' in the same position when it is loaded with acrylic resin.
Fig. 9. Imprints of the margins of the bearing plates in the Play Doh are relieved by 2 mm with a small wax spatula.
lower casts. Garefully lift off the upper and lower clutches from the teeth. R e m o v e the spacers from the clutches, remove the Play Doh and wax from the clutches and casts and trim the clutches to within 3 m m of the facial surfaces of the teeth. t0. Place the central bearing screw into the lower plate on a line connecting the distal contact points of the right and left first premolars. Attach the recording assembly and the transfer vise to the handles and u n m o u n t the lower cast. M a k i n g the transfers
1. Check the clutches in the m o u t h and adjust the central bearing screw so that the clutches do not interfere in excursions and the patient's m o u t h is not opened more than necessary. Practice protrusive and lateral movements with the patient. 2. Place the tracing paper on the recording tables and trace the Gothic arch tracings. Lock the vise in centric relation and remove it from the mouth. JANUARY1978 VOLUME39
NUMBER1
ARTICULATOR ADJUSTMENTS USING TRANSFER VISE
Fig. 10. A, on the right side of the articulator, the nonworking side for the first transfer, the condylar inclination set screw (a) is loosened; the Bennett guide (b) and the timing screw (c) are adjusted to maximum freedom. B, on the left side of the articulator, the working side for the first transfer, the axis rotation adjustment is moved into a lateroretrusive position.
3. Fill the space between the clutches in the second molar region with sticky wax for a d d e d stability. Set the incisal guide pin at m a x i m a l opening and m o u n t the lower cast using the transfer vise. Note that this centric relation m o u n t i n g is for the adjustment of the articulator only. Later the upper master cast will be m o u n t e d with a new facebow transfer, and the lower master cast will be m o u n t e d to the upper cast using centric occlusal registrations.9. 10 4. After the stone has set remove the incisal guide pin, remove the transfer vise from the casts, and cover the tracings with the protective overlays. 5. O n the outside portion of each Gothic arch tracing mark a point 3 m m and another 8 m m from centric relation. 6. The 8 mm transfer. Lock the vise with the styli on centric relation and place into the patient's mouth. Loosen the vise thumbscrews and have the patient move the jaw into a left lateral excursion until the stylus hits the 8 m m mark. A p p l y lateral pressure to the jaw for additional sideshift if you so desire. This additional sideshift will not show on the tracing; the stylus will remain on the 8 m m mark. However, there will be a difference in the a m o u n t of sideshift at the condyles. Tighten the vise and remove the instrument from the mouth. O n the right side of the articulator (Fig. 10, A), the nonworking side for this transfer, loosen the condylar inclination set screw (a) and adjust the Bennett guide (b) and the timing screw (c) to m a x i m u m freedom. O n the working side (Fig. 10, B) move the axis rotation adjustment into a lateroretrusion position. THE JOURNALOF PROSTHETICDENTISTRY
Fig. 11. The vise has been locked for the 8 mm transfer. The clutches have been stabilized with sticky wax (a) and placed between the casts. The condylar sphere (b) has moved down the condylar path and has set the condylar inclination automatically. The sphere also has moved toward the midsagittal plane, causing the rotating condylar plate (c) to turn. a
_f i / ~
2. | 1
~ B m~nFT |
2 ~
a |
Fig. 12. A, at the 8 mm transfer the condylar sphere has automatically set the angle of the condylar inclination. This angle is fixed by tightening the condylar inclination set screw (c). The Bennett guide (a) and the timing screw (b) so far have been adjusted for maximum sideshift. B, at the 8 mm transfer the condylar sphere has moved medially toward the midsagittal plane, turning the rotating condylar plate to an acute angle with the sagittal plane (1). C, at the 3 mm transfer the condylar sphere has turned the rotating condylar plate to a wider angle (2). D, this drawing indicates the location of the 3 mm transfer and the 8 mm transfer on a pantographic tracing if such is taken. (AB) indicates the immediate sideshift, (BC) t h e progressive sideshift. E, the top of the condylar housing has been removed to show the Bennett guide (a), the timing screw (b), and the rotating condylar plate. At the 8 mm transfer the Bennett guide is moved forward until it touches the condylar sphere; the guide is set in this position. At the 3 mm transfer the timing screw (b) is turned in until it touches the rotating condylar plate. This sets the angle of the immediate sideshift, 51
TRADOWSKY
TMJ RECORD (Incisal guide pin at zero) Patientls name: RIGHT
LEFT o
o
/0'
Condylar inclination Bennett guide (Progressive sideshift) Timing screw (Immediate sideshift)
,d.s17
Axis rotation Intercondylar
12. o
o
o LPv'~" ]
O,_o uP V-'-I
I~RV-J distance
LR
60
Fig. 13. Patient record of articulator settings. Stabilize the clutches with sticky wax (Fig. 11, [a]) and place them between the casts. As the casts settle into the clutches the condylar sphere (b), on the nonworking side, moves down the condylar path and sets the angle of condylar inclination automatically (Fig. 12, A). Tighten the condylar inclination set screw (c) in this position. At the same time as it moved down the condylar path, setting the condylar angle, the condylar sphere is also moved in toward the midsagittal plane, causing the rotating condylar plate to turn (Fig. 12, B). Slide the Bennett guide (Fig. 12, E, [a]) forward until it touches the condylar sphere in this 8 mm transfer position; then tighten its set screw. This establishes the progressive sideshift of the nonworking excursion. In the pantographic tracing this path would correspond to the second part of the tracing (Fig. 12, D, from [B] to [C].* 7. The 3 mm transfer. Remove the instrument from the casts and clean the sticky wax from between the clutches, Set the styli back on centric relation and place the clutches back into the mouth. Have the patient move the jaw to the 3 mm mark in left lateral excursion. Place lateral pressure on the jaw for additional sideshift if you wish and tighten the vise. Remove the instrument from the mouth and place the clutches between the casts; notice that the rotating condylar path turns more during the 3 mm transfer than during the 8 mm transfer (Fig. 12, C). As the condylar sphere (Fig. 12, E) has traveled from centric relation, (A), to the 3 mm transfer position, the rotating condylar plate has turned from a smaller angle (1) to a larger angle (2), in relation to the sagittal plane. Set this angle by turning in the timing screw (b) until it touches the condylar plate. On a pantographic tracing (Fig. 12, D) this adjustment *This part of the nonworking path is called progressive sideshifl.
52
would correspond to the first part of the nonworking excursion (A) to (B).* I t adjusts the direction in which the immediate sideshift occurs. With the articulator adjusted in this fashion the condylar sphere (Fig. 12, E) will now leave centric relation, (A), and travel down the condylar path with the condylar plate held by the timing screw at the angle of the immediate sideshift (2). The condylar sphere will travel through the 3 mm transfer position and on to a point, (B), where it makes first contact with the Bennett guide. From here on t h e condylar sphere travels along the Bennett guide, (B) to (C), through the 8 mm transfer position, turning the rotating condylar plate gradually from a larger to a smaller angle (2) to (1). 8. Make the same two transfers at the 8 mm and 3 mm mark in the patient's right lateral excursion to adjust the left condylar element of the articulator. Stabilization with sticky wax is not necessary for the 3 mm transfers. 9. The axis rotation and intercondylar distance are adjusted using the Gothic arch tracings in the same way that they are adjusted with the pantograph. 11 Loosen the vise and move the right stylus on the inner arm of the Gothic arch tracing. If it runs outside the tracing move the axis rotation adjustment on the right side into lateroprotrusion until the stylus follows the line. If the stylus is inside the tracing move the axis rotation adjustment into lateroretrusion until the stylus follows the line. Adjust on the left side. Now check the relation of the stylus to the outer portion of the Gothic arch tracing. If it runs outside the tracing increase the intercondylar distance on the opposite side. If the stylus runs inside the tracing decrease the intercondylar distance on the opposite side. Adjust both sides until both styli follow their tracings.
Recording the settings 1. Remove the transfer vise and casts from the articulator and set the incisal guide pin at 0. On the patient's record sheet (Fig. 13) fill in the right and left condylar inclinations as they are read on the articulator. 2. When recording the setting of the Bennett guide temporarily move the condylar inclination to 0. Measure the distance between the outer surface of the Bennett guide and the inner surface of the *This part of the nonworking path from centric relation to the beginning of the progressive path is called immediate sideshift,
JANUARY 1978
VOLUME 39
NUMBER 1
ARTICULATOR ADJUSTMENTS USING TRANSFER VISE
condylar housing with a Boley gauge to the nearest tenth of a millimeter (Fig. 14); the Boley gauge should touch the anterior edge of the square calibrated rod. R e c o r d this distance for the Bennett guide setting. 3. Record the timing screw settings. 4. When recording the axis rotation note whether the axis has been turned forward, which denotes lateroprotrusion (LP), or back, which denotes lateroretrusion (LR). 5. Record the intercondylar distance. DISCUSSION The described technique is simple and fast. It takes approximately 20 minutes for a dental laboratory technician to make the clutches and 20 minutes for the dentist to try-in the clutches, complete the recordings of the patient, and file the articulator settings in the patient's record. This time is regained m a n y times over, since future adjustments of the finished restorations in the m o u t h will be minimal. Should the patient move to another community records can be transferred to another dentist, provided he uses the same system. Transfer vise records compared to pantographic tracings. The transfer vise records do not yield as much information about the functioning temporomandibular joint as pantographic tracings. When used as described the transfer vise transfers the jaw relation at two points in each lateral excursion, while in pantographic tracings lateral excursions are presented by continuous lines. The two transfers are taken at two points on this line, at 8 m m and 3 m m from centric relation. The reason for these distances is that the lateral excursion on the nonworking side on the pantographic tracing can be divided into two parts (Fig. 12, D). The one part, [B] to [C], is produced by the progressive sideshift. On the Simulator articulator the progressive sideshift is mainmined by the Bennett guide. The Bennett guide forms an angle of 7.5 degrees to the sagittal plane. In all patients in which we have adjusted the Simulator to pantographic tracings (over 100 during the last 5 years) we have found none in which the Bennett guide would not adjust to the progressive path of the pantographic tracing. This has also been found by others.12. 13 There is consistency among individuals as far as the angle of the progressive sideshift to the sagittal plane is concerned. W h a t varies is the distance by which the angle of the progressive sideshift projects medially past the centric relation point (Fig. 12, D, [A]). This distance depends on the
THE JOURNAL OF PROSTHETIC DENTISTRY
l-ig. 14. For recording the setting of the Bennett guide the distance from the inner surface of the condylar housing to the outer surface of the Bennett guide is measured with a Boley gauge to the accuracy of 0.1 mm. For this measurement the condylar inclination should temporarily be set at 0 and the outer beak of the gauge should touch the square rod that holds the condylar element. individual characteristics of a given temporomandibular joint and also on the amount of lateral pressure applied to the jaw during the excursion. The o t h e r part of the tracing (Fig. 12, D, [A] to [B]) is produced by the immediate sideshift. It reflects the direction in which the nonworking condyle leaves the centric relation position and travels until it starts moving along the angle of the progressive sideshift. This first part of the excursion from centric position is usually at a greater angle than 7.5 degrees and varies from patient to patient. It also varies on the same patient with the amount of lateral pressure placed on the jaw during this excursion. Another variable is the distance AB, which the condyle will travel in the direction of the immediate sideshift until it begins to follow the 7.5 degree angle of the progressive sideshift. This distance depends on the angle of the immediate sideshift and on the distance by which the progressive sideshift runs medially to the centric relation point. The directional change between the immediate sideshift and the progressive sideshift occurs when the stylus on the Gothic arch tracing is somewhere between 4 m m and 6 m m away from centric relation. Therefore taking the transfers at 8 m m and 3 m m assures that the first recording is within the range of the progressive sideshift and that the second recording is within the range o f the immediate sideshift. The adjustment of the lateral excursion of the nonworking side using the transfer vise as described is an interpolation between the centric relation point
53
TRADOWSKY
a n d the two points o f lateral excursion transfer. I n instances where the dentist needs to analvze this excursion on a recorded c o n t i n u o u s line a n d where he needs to g r i n d in c o n d y l a r inserts a c c o r d i n g to this line, the transfer vise c a n n o t be used a n d p a n t o g r a p h i c tracings m u s t be taken. T r a n s f e r vise c o m p a r e d to checkbites w i t h stone. ~4 T h e m e t h o d o f t a k i n g checkbites with stone presents several problems. T h e patient has tO hold the j a w motionless in a lateral position while the stone sets. I n order t h a t this can be a c c o m p l i s h e d shallow depressions in which the central b e a r i n g screw can rest are drilled into the u p p e r plate. T h e d e p t h a n d size of these depressions are critical. I f the depressions are too shallow the p a t i e n t has difficulty finding t h e m or slips o u t of position while the stone is being injected or is setting. I f the depressions are too deep they allow the patient to relax the j a w muscles while the s u p p o r t of the central b e a r i n g screw is h o l d i n g the j a w in a lateral position. This p e r m i t s the m a n d i b l e to rotate a r o u n d the central b e a r m g screw into an atypical position a n d invalidates the interocclusal record. Besides this difficulty the m i x i n g of the stone, the filling of the plastic injection cone, the injecting o f the stone into the n a r r o w space between the b e a r i n g plates w i t h o u t the p a t i e n t o p e n i n g or m o v i n g the jaw. a n d the c l e a n i n g of the plates from stone after each transfer are s o m e w h a t time consuming and awkward. W i t h the use of the transfer vise a n y desired interocclusal relationship can be fixed instantly. Therefore there is no need to drill depressions into the central b e a r i n g plate. Also in the transfer vise t e c h n i q u e lateral pressure can be a p p l i e d to the j a w for a d d i t i o n a l sideshift. This is not possible with stone checkbites, since the stone takes too long to set to a d e q u a t e l y prevent the p a t i e n t from slipping into a different position if l a t e r a l pressure is a p p l i e d . A n o t h e r a d v a n t a g e o f the transfer vise over the stone checkbites is t h a t the transfers c a n be m a d e at m i n i m a l j a w opening. In the stone checkbite technique there must be room between the clutches to allow for the injection of stone. Therefore the interocclusal records are m a d e with a c o n s i d e r a b l e j a w opening, which m a y cause t r a n s l a t i o n of the condyles, p r o d u c i n g errors in the a r t i c u l a t o r adjustments. I n contrast the clutches for the transfer vise t e c h n i q u e are p a p e r thin over the incisal edges, a n d transfers are taken with a 1 to 2 m m s e p a r a t i o n of the Clutches. This small degree of j a w o p e n i n g m i n i m i z e s the c h a n c e of c o n d y l a r translation d u r i n g transfers.
54
T h e transfer vise used for r e m o v a b l e prostheses.
T h e transfer vise also can be used for the construction of r e m o v a b l e p a r t i a l a n d c o m p l e t e r e m o v a b l e prostheses. F o r r e m o v a b l e p a r t i a l d e n t u r e s acrylic resin baseplates are well a d a p t e d over the ridge areas. T h e n the p a r t o f the clutches w h i c h fits over the r e m a i n i n g teeth is m a d e as was previously described. I n blocking out the u n d e r c u t s care m u s t be t a k e n t h a t the acrylic resin over the teeth will c o m b i n e with the acrylic resin baseplates. F o r e d e n t u i o u s patients the trays are m a d e to fit the ridges well, a n d the central b e a r i n g plates a n d handles are fastened with self-curing acrylic resin; evenly d i v i d i n g the d i s t a n c e b e t w e e n the u p p e r a n d lower baseplates. T h e central b e a r i n g screw is set to the height of the p r e d e t e r m i n e d vertical d i m e n s i o n of occlusion, w h i c h later will be used for the setting of the teeth. T h e transfers for r e m o v a b l e prostheses are m a d e in the s a m e w a y as described for fixed prostheses. SUMMARY T h e transfer vise, a new i n s t r u m e n t t h a t is used fbr the a d j u s t m e n t of articulators, is described. Its a p p l i cation to one articulator, the S i m u l a t o r , is p r e s e n t e d in detail. T h e t e c h n i q u e using the transfer vise is c o m p a r e d to o t h e r existing techniques, a n d its a d v a n t a g e s a n d l i m i t a t i o n s are discussed. T h e transfer vise a n d its t e c h n i q u e are recomm e n d e d for the r o u t i n e t r e a t m e n t o f fixed a n d r e m o v a b l e p r o s t h o d o n t i c patients. REFERENCES
1. Tylman, S. D.: Theory and Practice of Grown and Bridge Prosthodontics, ed 5. St. Louis, 1965, The C. V. Mosby Company, pp 1090-1117. 2. Knap, F. J., and Ziebert, G. J.: "Checkbite" technique in major oral reconstruction. J PROSTHETDENT 21:458, 1969. 3. Stuart, C. E.: Instructions for Use of Gnathological Instruments. Ventura, Calif, 1973, C. E. Stuart Gnathological Instruments. 4. Amsterdam, M,, and Abrams, L.: Periodontal prosthesis. In Goldman, H. M., Schluger, S., Fox, L., and Cohen, D. W.: Periodontal Therapy, ed 3. St. Louis, 1964, The C. V. Mosby Company, 'pp 762-813. 5. Schuyler, C. H.: Factors contributing to traumatic occlusion. J PROSTHETDENT 11:708, 1961. 6. J. Aderer, Inc:: Instructions for the Simulator Minigraph. New York, 1969, J. Aderer, Inc. 7. Kornfeld, M.: Mouth Rehabilitation, vol 2. St. Louis, 1967, The C. V. Mosby Company, pp 445-451. 8. Brandrup-Wognsen, T.: The facebow, its significance and application. J PROSTHETDENT 3:618, 1953.
JANUARY 1978
VOLUME39
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ARTICULATOR ADJUSTMENTS USING TRANSFER VISE
9. Emmert, J. H.: A method for registering occlusion in semiedentulous mouths. J PROSa'nETDENT 8:94, 1958. 10. Lucia, V. O.: A technique for recording centric relation. J PROSTHET DENT 14:492, 1964. 11. Granger, E. R.: Practical Procedures in Oral Rehabilitation. Philadelphia, 1962, J. B. Lippincott Company, pp 155156. 12. Lundeen, H. C., and Wirth, C. G.: Condylar movement patterns engraved in plastic blocks. J PROSTHETDENT 30:866, 1973. 13. Gibbs, C. H., Reswick, J. B., and Messerman, T.: Functional
movements of the mandible. Case Western Reserve University, E.D.C. Report No. 4-69-24, 1969, pp 159-184. 14. J. Aderer, Inc.: Instructions for the Simulator Minigraph. New York, 1969, J. Aderer, Inc., pp 22-26. Reprint requests to: DR. MICHAEL TKADOWSKY CASE WESTERN RESERVE UNIVERSITY SCHOOL OF DENTISTRY
CLEVELAND, OHIO 44106
IADR PROSTHODONTIC ABSTRACT Occlusal force transmission by overdenture attachments-Additional studies H. H. Thayer and A. A. Caputo Sepulveda Veterans Administration Hospital and Biomaterials Science Section, University of California School of Dentistry, Los Angeles, Calif. Recent investigations have been concerned with the load transfer characteristics of specifc o v e r d e n t u r e designs. T h e purpose of this study was to examine additional a t t a c h m e n t s a n d to provide more t h o r o u g h guidelines for their selection a n d p o t e n t i a l clinical use. Using the techniques of the previous studies, a partially edentulous m a n d i b u l a r arch with only the endodontically treated c a n i n e teeth r e m a i n i n g was reproduced in photoelastic plastics. I n d i v i d u a l birefringent materials were used to simulate teeth, bone, a n d periodontal ligament. T h e following a t t a c h m e n t s were tested: (a) tissue b a r t y p e - - H a d e r Bar a n d K i n g Connector, (b) stud t y p e - - R o t h e r m a n , Gerber, Reprinted from the Journal of Dental Research with permission of the author and the editor.
THE JOURNAL OF PROSTHETIC DENTISTRY
Ancrofix a n d Introfix. Directional occlusal loads were applied to the various overdentures a n d the stresses generated within the s u p p o r t i n g substructures were recorded photographically. T h e more retentive K i n g Connector was observed to generate greater stresses t h a n the H a d e r b a r for all applied load directions. T h e r e was also more cross-arch i n v o l v e m e n t with the K i n g Com3ector. T h e extracoronal stud a t t a c h m e n t s tested produced a different response to the s u p p o r t i n g structures as c o m p a r e d to the i n t r a c o r o n a l attachments studied previously. Generally, the more retentive a t t a c h m e n t s p r o d u c e d higher stress concentrations. Consequently, the relative h e a l t h of the period o n t i u m a n d its preservation must be considered when selecting a n a t t a c h m e n t for particular clinical situations.
55
adjustable articulators so that individual articulator settings can be obtained. Among the many ways articulators have been adjusted to jaw movements of individual patients, checkbite 1. 2 and pantographic tracing a techniques have predominated. Checkbite techniques serve edentulous patients, and the pantographic tracing technique is used with patients requiring repositioning of the mandible and reconstruction of the occlusal surfaces of the teeth. In addition to patients needing complete dentures or occlusal reconstruction, there is a large group of patients needing posterior fixed restorations. These restorations too often are made where the individual characteristics of the patient's temporomandibular joints are ignored. The dentist compensates for this omission by "grinding-in" the restorations. This is costly and time-consuming," and where the grindingin procedure is incomplete occlusal interferences may initiate periodontal breakdown?' 5 The transfer vise technique is helpful in the treatment of these patients, and it may serve as an adjunct to existing methods.
frictionally gripped between the respective pairs of jaws and fixed in a given position. Besides the transfer vise the clutch handles carry a twin Gothi c arch (needle point) tracing mechanism (Fig. 2, A, [j] to [/]). The tracing tables (j) are attached to the lower handle (d), and the styli (k) are attached to the upper handle (c) by the stylus bar (l). The handles are attached to acrylic resin clutches (Fig. 2, B, [a]). Embedded on the lingual side of the clutches are the upper and lower metal central bearing plates ([b] and [c]). The lower central bearing plate carries the central bearing screw (d), which rides on the upper central bearing plate in the usual manner. After the patient has traced twin Gothic arches the dentist can see the location of centric relation and lock the transfer vise in this position for remounting of the lower cast. Also the jaw can be moved into various measurable excursions and the transfer vise can be locked into these positions. Each eccentric jaw relation and protrusive, right, and left lateral position can be transferred to mounted casts for the adjustment of the articulator. The combination of the tracing assembly and the transfer vise is called the "Minigraph System. ''*~
DESCRIPTION OF THE TRANSFER VISE
METHOD
The transfer vise (Fig. 1) is a mechanism which allows the instant fixation of the jaw in centric relation or any eccentric position. Two transverse bars(Fig. 2, A, [a] and [b]) are attached to upper and lower clutch handles (c) and (d). The spherical end portions (e) and (f) of these transverse bars are engaged between pairs of curved vise jaws (g). These vise jaws are retained by screws (h) and (i) for universal movement. Upon tightening of the knurled thumbscrew (i) the pair of spheres (e) and (f) are
Although the following method describes the transfer vise technique as used with the Simulator articulator,* it also can be used for setting other adjustable articulators.
This
article describes a new instrument, the
transfer vise,'~ which is used to transfer jaw positions to
"*Associate Professor and Chairman, Department of Fixed Prosthodontics. tJ. Aderer, Inc., Long Island City, N. Y.
THE JOURNALOF PROSTHETICDENTISTRY
Preliminary procedures Obtain a set of accurate diagnostic casts. The upper cast should be mounted to three reference points: the right and left hinge axis points and an anterior reference point. The hinge axis points can either be accurately determined 7 or estimated. 8 Usually the estimated hinge axis points are used with *J. Aderer, Inc., Long Island City, N. Y
47
TRADOWSKY
Fig. 1. The transfer vise and Minigraph have been attached to the patient's teeth through clutches. k
k
|
i!
Fig. 3. Anterior reference point jig positioned on patient's nose for marking the anterior reference point. h @--
tJ
(1
g
| Fig. 2. A, the transfer vise consisting of the transverse bars (a) and (b), the spherical end portions (e) and (f), and the pairs of curved vise jaws (g), which are retained by the screws (h) and (i). The transfer vise is attached to a Minigraph consisting of upper and lower clutch handles (c) and (d), the tracing tables 0), and the styli (k), which are retained by the stylus bar (l). When the knurled thumb screws (i) are loosened the patient can move the jaw freely in excursions and trace twin Gothic arch tracings. When the knurled thumb screws are tightened the vise and the clutches are fixed in a given position. The jaw relation can then be transferred to mounted casts for articulator adjustments. B, midsagittal crossection of the vise, tracing mechanism, and clutches. Acrylic resin (a) holds the upper and lower bearing plates (b) and (c). The lower bearing plate carries a central bearing screw (d).
the transfer Vise technique. For the determination of the anterior reference point an anterior reference point jig is used (Fig. 3). This jig is a perpendicular plastic angle with a long and a short leg. T h e long leg has an engraved midline with a hole on it 20 m m
48
away from the angle. T h e anterior reference point is marked through the hole after the midline on the jig is superimposed on the midline of the patient's face. T h e angle rests gently against the tip of the nose. T h e advantage of the jig is that the dentist can locate the third reference point accurately at any time in the future. T h e lower cast is m o u n t e d by h a n d articulation or with a wax or a zinc oxide/eugenol centric relation registration. T h e incisal guide pin is set at 0. T h e precision of the m o u n t i n g of the lower cast at this point is not critical because the lower cast will be remounted using the transfer vise. This m o u n t i n g is used for making the clutches only. Fabrication of c l u t c h e s
The clutches are m a d e between appointments by a dental laboratory technician. From a m o n g the several ways in which clutches and transfers can be made, the following guidelines have been selected for their ease, speed, and accuracy of procedure: 1. Prepare the clutch former assembly (Fig. 4). It consists of the lower central bearing plate (a), the lower plastic spacer (b), the occlusal sheet (c), the upper plastic spacer (d), and the upper central bearing plate (e). T h e components are held together by the clutch assembly screw (f) and the nut (g). T h e plastic spacers are 0.04-inch-thick vinyl resin sheets having the same shape as the bearing plates. T h e y are slightly smaller so that a recess is created under the slanted sides and the short front of the bearing plates, providing space into which the acrylic resin of
JANUARY 1978
VOLUME 39
NUMBER 1
ARTICULATOR ADJUSTMENTS USING TRANSFER VISE
the clutches can engage. The occlusal sheet is 0.02inch-thick vinyl resin that extends approximately 5 m m beyond the facial surfaces of the upper teeth when placed between the dental arches. When the articulator is closed the sheet bends according to the occlusal curvature of the arches. Place the clutch assembly screw through the back hole of the lower central bearing plate, then through the lower plastic spacer, the occlusal sheet, the upper plastic spacer, and the upper bearing plate. Place the nut on the screw, center all components, and tighten the nut. 2. Place the clutch former assembly between the casts (Fig. 5) and adjust the handles on their spacer bar so that they touch the labial surfaces of the upper and lower anterior teeth while being held parallel to the occlusal plane. 3. On the lower bearing plate place beading wax into the slot and over the screw head (Fig. 6, A). Also run beading wax 2 m m inside of the margin of the bearing plate and onto the occlusal sheet to its posterior rim. The wax will prevent acrylic resin from running onto parts of the bearing plate that should stay exposed during clutch formation. On the upper bearing plate, as on the lower, cover the nut with beading wax and run beading wax 2 m m away from the margin out to the occlusal sheet to its posterior margin (Fig. 6, B). Make sure that the space between the wax walls on the occlusal sheet is wide enough to permit the wrench to engage the clutch assembly nut after the clutches have been formed. 4. Cover all surfaces below the height of contour on the upper and lower dental arches with Play Doh (Fig 7).* With a small spatula block out all of the undercuts between the teeth and fill in the lingual and palatal regions. The Play Doh should meet these surfaces of the teeth at a 90 degree angle. Using a plaster knife cut the Play Doh vertically, 3 m m from the facial surfaces. In the anterior region press the Play Doh out of the way to make room for the handles. 5. Coat the teeth with a foil substitute. 6. Place the clutch former assembly over the lower dental arch, pressing it down into the Play Doh. Close the articulator and press down until the occlusal sheet bends according to the occlusal pressure of the teeth. Project a vertical line from the upper anterior rim of the Play Doh onto the occlusal sheet and mark this line with a pen (Fig. 8). This line *Kenner Products, Cincinnati, Ohio.
THE JOURNAL OF PROSTHETIC DENTISTRY
g
|
\
I
d-\ m
I
Fig. 4. An exploded view of the clutch former assembly consisting of the lower central bearing plate (a), the lower plastic spacer (b), the occlusal sheet (c), the upper plastic spacer (d), the upper center bearing plate (e), the clutch assembly screw (/), and nut (g).
Fig. 5. The clutch former assembly has been placed between the casts and the handles have been adjusted according to the amount of horizontal overlap. will help to reposition the clutch former assembly when it is loaded with acrylic resin. 7. Open the articulator and remove the clutch former assembly. Where the margins of the bearing plates are imprinted into the Play Doh on the upper and lower arch, relieve 2 m m with a small wax spatula (Fig. 9). This will aid in locking the bearing plates into the acrylic resin. Readjust the blockedout regions on the lingual and palatal surfaces of the teeth if necessary.
49
TRADOWSKY
Fig. 6. A, on the lower bearing plate, areas which have to stay free from acrylic resin have been isolated with beading wax. B, wax on the upper bearing plate.
Fig. 7. Upper and lower casts blocked out below the height of contour with Play Doh. 8~ Mix enough cold-cure denture tray material for both clutches (the mix should be thin). A p p l y it over the upper and lower teeth with a tongue blade. Wipe the resin a r o u n d the u p p e r and lower bearing plates, making sure that the notches formed by the spacers are filled. Place the loaded clutch former assembly on the lower cast and close the articulator. Adjust the position of the clutch former assembly so that the mark on the occlusal sheet is lined up as it was previously. Incorporate the handles into the clutches by a d a p t i n g the acrylic resin a r o u n d them with a small wax spatula. Support the handles with Play D o h placed on the incisal guide table so that they stay parallel to the occlusal plane. Verify that the upper and lower acrylic resin clutches are not in contact and allow them to set. 9. After the resin has set remove the casts from the articulator. Unscrew the Allen screw from the u p p e r handle and dig through the wax to the clutch assembly nut and unscrew it. Separate the u p p e r and SO
Fig. 8. A vertical line is dropped from the anterior margin of the Play Doh onto the occlusal sheet. This marked line will help reposition the clutch former assembly' in the same position when it is loaded with acrylic resin.
Fig. 9. Imprints of the margins of the bearing plates in the Play Doh are relieved by 2 mm with a small wax spatula.
lower casts. Garefully lift off the upper and lower clutches from the teeth. R e m o v e the spacers from the clutches, remove the Play Doh and wax from the clutches and casts and trim the clutches to within 3 m m of the facial surfaces of the teeth. t0. Place the central bearing screw into the lower plate on a line connecting the distal contact points of the right and left first premolars. Attach the recording assembly and the transfer vise to the handles and u n m o u n t the lower cast. M a k i n g the transfers
1. Check the clutches in the m o u t h and adjust the central bearing screw so that the clutches do not interfere in excursions and the patient's m o u t h is not opened more than necessary. Practice protrusive and lateral movements with the patient. 2. Place the tracing paper on the recording tables and trace the Gothic arch tracings. Lock the vise in centric relation and remove it from the mouth. JANUARY1978 VOLUME39
NUMBER1
ARTICULATOR ADJUSTMENTS USING TRANSFER VISE
Fig. 10. A, on the right side of the articulator, the nonworking side for the first transfer, the condylar inclination set screw (a) is loosened; the Bennett guide (b) and the timing screw (c) are adjusted to maximum freedom. B, on the left side of the articulator, the working side for the first transfer, the axis rotation adjustment is moved into a lateroretrusive position.
3. Fill the space between the clutches in the second molar region with sticky wax for a d d e d stability. Set the incisal guide pin at m a x i m a l opening and m o u n t the lower cast using the transfer vise. Note that this centric relation m o u n t i n g is for the adjustment of the articulator only. Later the upper master cast will be m o u n t e d with a new facebow transfer, and the lower master cast will be m o u n t e d to the upper cast using centric occlusal registrations.9. 10 4. After the stone has set remove the incisal guide pin, remove the transfer vise from the casts, and cover the tracings with the protective overlays. 5. O n the outside portion of each Gothic arch tracing mark a point 3 m m and another 8 m m from centric relation. 6. The 8 mm transfer. Lock the vise with the styli on centric relation and place into the patient's mouth. Loosen the vise thumbscrews and have the patient move the jaw into a left lateral excursion until the stylus hits the 8 m m mark. A p p l y lateral pressure to the jaw for additional sideshift if you so desire. This additional sideshift will not show on the tracing; the stylus will remain on the 8 m m mark. However, there will be a difference in the a m o u n t of sideshift at the condyles. Tighten the vise and remove the instrument from the mouth. O n the right side of the articulator (Fig. 10, A), the nonworking side for this transfer, loosen the condylar inclination set screw (a) and adjust the Bennett guide (b) and the timing screw (c) to m a x i m u m freedom. O n the working side (Fig. 10, B) move the axis rotation adjustment into a lateroretrusion position. THE JOURNALOF PROSTHETICDENTISTRY
Fig. 11. The vise has been locked for the 8 mm transfer. The clutches have been stabilized with sticky wax (a) and placed between the casts. The condylar sphere (b) has moved down the condylar path and has set the condylar inclination automatically. The sphere also has moved toward the midsagittal plane, causing the rotating condylar plate (c) to turn. a
_f i / ~
2. | 1
~ B m~nFT |
2 ~
a |
Fig. 12. A, at the 8 mm transfer the condylar sphere has automatically set the angle of the condylar inclination. This angle is fixed by tightening the condylar inclination set screw (c). The Bennett guide (a) and the timing screw (b) so far have been adjusted for maximum sideshift. B, at the 8 mm transfer the condylar sphere has moved medially toward the midsagittal plane, turning the rotating condylar plate to an acute angle with the sagittal plane (1). C, at the 3 mm transfer the condylar sphere has turned the rotating condylar plate to a wider angle (2). D, this drawing indicates the location of the 3 mm transfer and the 8 mm transfer on a pantographic tracing if such is taken. (AB) indicates the immediate sideshift, (BC) t h e progressive sideshift. E, the top of the condylar housing has been removed to show the Bennett guide (a), the timing screw (b), and the rotating condylar plate. At the 8 mm transfer the Bennett guide is moved forward until it touches the condylar sphere; the guide is set in this position. At the 3 mm transfer the timing screw (b) is turned in until it touches the rotating condylar plate. This sets the angle of the immediate sideshift, 51
TRADOWSKY
TMJ RECORD (Incisal guide pin at zero) Patientls name: RIGHT
LEFT o
o
/0'
Condylar inclination Bennett guide (Progressive sideshift) Timing screw (Immediate sideshift)
,d.s17
Axis rotation Intercondylar
12. o
o
o LPv'~" ]
O,_o uP V-'-I
I~RV-J distance
LR
60
Fig. 13. Patient record of articulator settings. Stabilize the clutches with sticky wax (Fig. 11, [a]) and place them between the casts. As the casts settle into the clutches the condylar sphere (b), on the nonworking side, moves down the condylar path and sets the angle of condylar inclination automatically (Fig. 12, A). Tighten the condylar inclination set screw (c) in this position. At the same time as it moved down the condylar path, setting the condylar angle, the condylar sphere is also moved in toward the midsagittal plane, causing the rotating condylar plate to turn (Fig. 12, B). Slide the Bennett guide (Fig. 12, E, [a]) forward until it touches the condylar sphere in this 8 mm transfer position; then tighten its set screw. This establishes the progressive sideshift of the nonworking excursion. In the pantographic tracing this path would correspond to the second part of the tracing (Fig. 12, D, from [B] to [C].* 7. The 3 mm transfer. Remove the instrument from the casts and clean the sticky wax from between the clutches, Set the styli back on centric relation and place the clutches back into the mouth. Have the patient move the jaw to the 3 mm mark in left lateral excursion. Place lateral pressure on the jaw for additional sideshift if you wish and tighten the vise. Remove the instrument from the mouth and place the clutches between the casts; notice that the rotating condylar path turns more during the 3 mm transfer than during the 8 mm transfer (Fig. 12, C). As the condylar sphere (Fig. 12, E) has traveled from centric relation, (A), to the 3 mm transfer position, the rotating condylar plate has turned from a smaller angle (1) to a larger angle (2), in relation to the sagittal plane. Set this angle by turning in the timing screw (b) until it touches the condylar plate. On a pantographic tracing (Fig. 12, D) this adjustment *This part of the nonworking path is called progressive sideshifl.
52
would correspond to the first part of the nonworking excursion (A) to (B).* I t adjusts the direction in which the immediate sideshift occurs. With the articulator adjusted in this fashion the condylar sphere (Fig. 12, E) will now leave centric relation, (A), and travel down the condylar path with the condylar plate held by the timing screw at the angle of the immediate sideshift (2). The condylar sphere will travel through the 3 mm transfer position and on to a point, (B), where it makes first contact with the Bennett guide. From here on t h e condylar sphere travels along the Bennett guide, (B) to (C), through the 8 mm transfer position, turning the rotating condylar plate gradually from a larger to a smaller angle (2) to (1). 8. Make the same two transfers at the 8 mm and 3 mm mark in the patient's right lateral excursion to adjust the left condylar element of the articulator. Stabilization with sticky wax is not necessary for the 3 mm transfers. 9. The axis rotation and intercondylar distance are adjusted using the Gothic arch tracings in the same way that they are adjusted with the pantograph. 11 Loosen the vise and move the right stylus on the inner arm of the Gothic arch tracing. If it runs outside the tracing move the axis rotation adjustment on the right side into lateroprotrusion until the stylus follows the line. If the stylus is inside the tracing move the axis rotation adjustment into lateroretrusion until the stylus follows the line. Adjust on the left side. Now check the relation of the stylus to the outer portion of the Gothic arch tracing. If it runs outside the tracing increase the intercondylar distance on the opposite side. If the stylus runs inside the tracing decrease the intercondylar distance on the opposite side. Adjust both sides until both styli follow their tracings.
Recording the settings 1. Remove the transfer vise and casts from the articulator and set the incisal guide pin at 0. On the patient's record sheet (Fig. 13) fill in the right and left condylar inclinations as they are read on the articulator. 2. When recording the setting of the Bennett guide temporarily move the condylar inclination to 0. Measure the distance between the outer surface of the Bennett guide and the inner surface of the *This part of the nonworking path from centric relation to the beginning of the progressive path is called immediate sideshift,
JANUARY 1978
VOLUME 39
NUMBER 1
ARTICULATOR ADJUSTMENTS USING TRANSFER VISE
condylar housing with a Boley gauge to the nearest tenth of a millimeter (Fig. 14); the Boley gauge should touch the anterior edge of the square calibrated rod. R e c o r d this distance for the Bennett guide setting. 3. Record the timing screw settings. 4. When recording the axis rotation note whether the axis has been turned forward, which denotes lateroprotrusion (LP), or back, which denotes lateroretrusion (LR). 5. Record the intercondylar distance. DISCUSSION The described technique is simple and fast. It takes approximately 20 minutes for a dental laboratory technician to make the clutches and 20 minutes for the dentist to try-in the clutches, complete the recordings of the patient, and file the articulator settings in the patient's record. This time is regained m a n y times over, since future adjustments of the finished restorations in the m o u t h will be minimal. Should the patient move to another community records can be transferred to another dentist, provided he uses the same system. Transfer vise records compared to pantographic tracings. The transfer vise records do not yield as much information about the functioning temporomandibular joint as pantographic tracings. When used as described the transfer vise transfers the jaw relation at two points in each lateral excursion, while in pantographic tracings lateral excursions are presented by continuous lines. The two transfers are taken at two points on this line, at 8 m m and 3 m m from centric relation. The reason for these distances is that the lateral excursion on the nonworking side on the pantographic tracing can be divided into two parts (Fig. 12, D). The one part, [B] to [C], is produced by the progressive sideshift. On the Simulator articulator the progressive sideshift is mainmined by the Bennett guide. The Bennett guide forms an angle of 7.5 degrees to the sagittal plane. In all patients in which we have adjusted the Simulator to pantographic tracings (over 100 during the last 5 years) we have found none in which the Bennett guide would not adjust to the progressive path of the pantographic tracing. This has also been found by others.12. 13 There is consistency among individuals as far as the angle of the progressive sideshift to the sagittal plane is concerned. W h a t varies is the distance by which the angle of the progressive sideshift projects medially past the centric relation point (Fig. 12, D, [A]). This distance depends on the
THE JOURNAL OF PROSTHETIC DENTISTRY
l-ig. 14. For recording the setting of the Bennett guide the distance from the inner surface of the condylar housing to the outer surface of the Bennett guide is measured with a Boley gauge to the accuracy of 0.1 mm. For this measurement the condylar inclination should temporarily be set at 0 and the outer beak of the gauge should touch the square rod that holds the condylar element. individual characteristics of a given temporomandibular joint and also on the amount of lateral pressure applied to the jaw during the excursion. The o t h e r part of the tracing (Fig. 12, D, [A] to [B]) is produced by the immediate sideshift. It reflects the direction in which the nonworking condyle leaves the centric relation position and travels until it starts moving along the angle of the progressive sideshift. This first part of the excursion from centric position is usually at a greater angle than 7.5 degrees and varies from patient to patient. It also varies on the same patient with the amount of lateral pressure placed on the jaw during this excursion. Another variable is the distance AB, which the condyle will travel in the direction of the immediate sideshift until it begins to follow the 7.5 degree angle of the progressive sideshift. This distance depends on the angle of the immediate sideshift and on the distance by which the progressive sideshift runs medially to the centric relation point. The directional change between the immediate sideshift and the progressive sideshift occurs when the stylus on the Gothic arch tracing is somewhere between 4 m m and 6 m m away from centric relation. Therefore taking the transfers at 8 m m and 3 m m assures that the first recording is within the range of the progressive sideshift and that the second recording is within the range o f the immediate sideshift. The adjustment of the lateral excursion of the nonworking side using the transfer vise as described is an interpolation between the centric relation point
53
TRADOWSKY
a n d the two points o f lateral excursion transfer. I n instances where the dentist needs to analvze this excursion on a recorded c o n t i n u o u s line a n d where he needs to g r i n d in c o n d y l a r inserts a c c o r d i n g to this line, the transfer vise c a n n o t be used a n d p a n t o g r a p h i c tracings m u s t be taken. T r a n s f e r vise c o m p a r e d to checkbites w i t h stone. ~4 T h e m e t h o d o f t a k i n g checkbites with stone presents several problems. T h e patient has tO hold the j a w motionless in a lateral position while the stone sets. I n order t h a t this can be a c c o m p l i s h e d shallow depressions in which the central b e a r i n g screw can rest are drilled into the u p p e r plate. T h e d e p t h a n d size of these depressions are critical. I f the depressions are too shallow the p a t i e n t has difficulty finding t h e m or slips o u t of position while the stone is being injected or is setting. I f the depressions are too deep they allow the patient to relax the j a w muscles while the s u p p o r t of the central b e a r i n g screw is h o l d i n g the j a w in a lateral position. This p e r m i t s the m a n d i b l e to rotate a r o u n d the central b e a r m g screw into an atypical position a n d invalidates the interocclusal record. Besides this difficulty the m i x i n g of the stone, the filling of the plastic injection cone, the injecting o f the stone into the n a r r o w space between the b e a r i n g plates w i t h o u t the p a t i e n t o p e n i n g or m o v i n g the jaw. a n d the c l e a n i n g of the plates from stone after each transfer are s o m e w h a t time consuming and awkward. W i t h the use of the transfer vise a n y desired interocclusal relationship can be fixed instantly. Therefore there is no need to drill depressions into the central b e a r i n g plate. Also in the transfer vise t e c h n i q u e lateral pressure can be a p p l i e d to the j a w for a d d i t i o n a l sideshift. This is not possible with stone checkbites, since the stone takes too long to set to a d e q u a t e l y prevent the p a t i e n t from slipping into a different position if l a t e r a l pressure is a p p l i e d . A n o t h e r a d v a n t a g e o f the transfer vise over the stone checkbites is t h a t the transfers c a n be m a d e at m i n i m a l j a w opening. In the stone checkbite technique there must be room between the clutches to allow for the injection of stone. Therefore the interocclusal records are m a d e with a c o n s i d e r a b l e j a w opening, which m a y cause t r a n s l a t i o n of the condyles, p r o d u c i n g errors in the a r t i c u l a t o r adjustments. I n contrast the clutches for the transfer vise t e c h n i q u e are p a p e r thin over the incisal edges, a n d transfers are taken with a 1 to 2 m m s e p a r a t i o n of the Clutches. This small degree of j a w o p e n i n g m i n i m i z e s the c h a n c e of c o n d y l a r translation d u r i n g transfers.
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T h e transfer vise used for r e m o v a b l e prostheses.
T h e transfer vise also can be used for the construction of r e m o v a b l e p a r t i a l a n d c o m p l e t e r e m o v a b l e prostheses. F o r r e m o v a b l e p a r t i a l d e n t u r e s acrylic resin baseplates are well a d a p t e d over the ridge areas. T h e n the p a r t o f the clutches w h i c h fits over the r e m a i n i n g teeth is m a d e as was previously described. I n blocking out the u n d e r c u t s care m u s t be t a k e n t h a t the acrylic resin over the teeth will c o m b i n e with the acrylic resin baseplates. F o r e d e n t u i o u s patients the trays are m a d e to fit the ridges well, a n d the central b e a r i n g plates a n d handles are fastened with self-curing acrylic resin; evenly d i v i d i n g the d i s t a n c e b e t w e e n the u p p e r a n d lower baseplates. T h e central b e a r i n g screw is set to the height of the p r e d e t e r m i n e d vertical d i m e n s i o n of occlusion, w h i c h later will be used for the setting of the teeth. T h e transfers for r e m o v a b l e prostheses are m a d e in the s a m e w a y as described for fixed prostheses. SUMMARY T h e transfer vise, a new i n s t r u m e n t t h a t is used fbr the a d j u s t m e n t of articulators, is described. Its a p p l i cation to one articulator, the S i m u l a t o r , is p r e s e n t e d in detail. T h e t e c h n i q u e using the transfer vise is c o m p a r e d to o t h e r existing techniques, a n d its a d v a n t a g e s a n d l i m i t a t i o n s are discussed. T h e transfer vise a n d its t e c h n i q u e are recomm e n d e d for the r o u t i n e t r e a t m e n t o f fixed a n d r e m o v a b l e p r o s t h o d o n t i c patients. REFERENCES
1. Tylman, S. D.: Theory and Practice of Grown and Bridge Prosthodontics, ed 5. St. Louis, 1965, The C. V. Mosby Company, pp 1090-1117. 2. Knap, F. J., and Ziebert, G. J.: "Checkbite" technique in major oral reconstruction. J PROSTHETDENT 21:458, 1969. 3. Stuart, C. E.: Instructions for Use of Gnathological Instruments. Ventura, Calif, 1973, C. E. Stuart Gnathological Instruments. 4. Amsterdam, M,, and Abrams, L.: Periodontal prosthesis. In Goldman, H. M., Schluger, S., Fox, L., and Cohen, D. W.: Periodontal Therapy, ed 3. St. Louis, 1964, The C. V. Mosby Company, 'pp 762-813. 5. Schuyler, C. H.: Factors contributing to traumatic occlusion. J PROSTHETDENT 11:708, 1961. 6. J. Aderer, Inc:: Instructions for the Simulator Minigraph. New York, 1969, J. Aderer, Inc. 7. Kornfeld, M.: Mouth Rehabilitation, vol 2. St. Louis, 1967, The C. V. Mosby Company, pp 445-451. 8. Brandrup-Wognsen, T.: The facebow, its significance and application. J PROSTHETDENT 3:618, 1953.
JANUARY 1978
VOLUME39
NUMBER1
ARTICULATOR ADJUSTMENTS USING TRANSFER VISE
9. Emmert, J. H.: A method for registering occlusion in semiedentulous mouths. J PROSa'nETDENT 8:94, 1958. 10. Lucia, V. O.: A technique for recording centric relation. J PROSTHET DENT 14:492, 1964. 11. Granger, E. R.: Practical Procedures in Oral Rehabilitation. Philadelphia, 1962, J. B. Lippincott Company, pp 155156. 12. Lundeen, H. C., and Wirth, C. G.: Condylar movement patterns engraved in plastic blocks. J PROSTHETDENT 30:866, 1973. 13. Gibbs, C. H., Reswick, J. B., and Messerman, T.: Functional
movements of the mandible. Case Western Reserve University, E.D.C. Report No. 4-69-24, 1969, pp 159-184. 14. J. Aderer, Inc.: Instructions for the Simulator Minigraph. New York, 1969, J. Aderer, Inc., pp 22-26. Reprint requests to: DR. MICHAEL TKADOWSKY CASE WESTERN RESERVE UNIVERSITY SCHOOL OF DENTISTRY
CLEVELAND, OHIO 44106
IADR PROSTHODONTIC ABSTRACT Occlusal force transmission by overdenture attachments-Additional studies H. H. Thayer and A. A. Caputo Sepulveda Veterans Administration Hospital and Biomaterials Science Section, University of California School of Dentistry, Los Angeles, Calif. Recent investigations have been concerned with the load transfer characteristics of specifc o v e r d e n t u r e designs. T h e purpose of this study was to examine additional a t t a c h m e n t s a n d to provide more t h o r o u g h guidelines for their selection a n d p o t e n t i a l clinical use. Using the techniques of the previous studies, a partially edentulous m a n d i b u l a r arch with only the endodontically treated c a n i n e teeth r e m a i n i n g was reproduced in photoelastic plastics. I n d i v i d u a l birefringent materials were used to simulate teeth, bone, a n d periodontal ligament. T h e following a t t a c h m e n t s were tested: (a) tissue b a r t y p e - - H a d e r Bar a n d K i n g Connector, (b) stud t y p e - - R o t h e r m a n , Gerber, Reprinted from the Journal of Dental Research with permission of the author and the editor.
THE JOURNAL OF PROSTHETIC DENTISTRY
Ancrofix a n d Introfix. Directional occlusal loads were applied to the various overdentures a n d the stresses generated within the s u p p o r t i n g substructures were recorded photographically. T h e more retentive K i n g Connector was observed to generate greater stresses t h a n the H a d e r b a r for all applied load directions. T h e r e was also more cross-arch i n v o l v e m e n t with the K i n g Com3ector. T h e extracoronal stud a t t a c h m e n t s tested produced a different response to the s u p p o r t i n g structures as c o m p a r e d to the i n t r a c o r o n a l attachments studied previously. Generally, the more retentive a t t a c h m e n t s p r o d u c e d higher stress concentrations. Consequently, the relative h e a l t h of the period o n t i u m a n d its preservation must be considered when selecting a n a t t a c h m e n t for particular clinical situations.
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