- Email: [email protected]
Procedural problems in using the Denar pantograph as a transfer-bow
Procedural problems in using the Denar pantograph as a transfer-bow Donald B. Beck, D.D.S.,* Charles A. Kass, D.D.S., M.S.,** and Florian J. Knap, D.D.S., M.S.*** University of the Pacific, School of Dentistry, San Francisco, Calif., and Marquette University, School of Dentistry, Milwaukee, Wis.
Attempts at utilizing the Denar p a n t o g r a p h t as a transfer-bow, following the instructions in the Denar manual, resulted in a movement of the posterior horizontal styli away from the recorded centric relation position. 1 A method of transferring the Denar pantograph to the Denar D5A articulator using an interclutch support to maintain a stable centric relation is described in this article. PROCEDURE Custom plastic clutches are made for the patient following the technique outlined in the Denar manual. After the acrylic resin sets both clutches are trimmed with a vulcanite bur leaving only the indentations from the cusp tips and incisa] edges (Fig. 1). The central bearing pin surface of the mandibular clutch and the central bearing surface of the maxillary clutch are lubricated with petroleum jelly to facilitate the removal of the interclutch support at a later step. The maxillary clutch is dried with air and the tooth imprints are lined with a zincoxide/eugenol paste.~ The clutch is then seated on the maxillary teeth and held until the paste hardens. The mandibular clutch is inserted with no paste and the central bearing screw is adjusted to provide 0.5 mm clearance between the two clutches throughout all border excursions. The mandibular clutch is removed, dried with air, lined with zinc-oxide/and eugenol paste, and secured to the mandibular teeth. The subject is then instructed to perform the jaw movements needed to obtain pantographic record*Assistant Professor. Department of Fixed Prosthodontics. **Associate Professor and Head of Clinical Fixed Prosthodontics. ***Professorand Director of Occlusion. tDenar Corp., Anaheim, Calif. ~Kerr bite registration paste, Kerr Mfg. Co., Romulus, Mich.
I66
FEBRUARY1978 VOLUME39
NUMBER2
ings. When the movements are mastered the pantograph is-assembled and the recordings obtained according to the prescribed manner. When the tracings are determined to b e acceptable, clear plastic overlays are placed over the recordings to prevent accidental extraneous markings. The maxillary and mandibular bows of the pantograph must then be related to one another to accurately transfer the pantographic apparatus to the articulator. This transfer is one of the most critical steps in the entire pantographic procedure. If the bows of the pantograph are aligned differently on thearticulator than they were on the subject the fidelity of the entire pantographic procedure is lost. The same kind of zinc-oxide/eugenol paste previously used to secure the clutches to the teeth is also used for the interclutch support. The paste is mixed and placed in either a glass cylinder syringe, which has a soft, flexible rubber tip, or in a disposable plastic syringe (Fig. 2). The subject is instructed to open the jaws sufficiently to allow for the insertion of the syringe tip, and the paste is then injected onto the lubricated surface of the mandibular clutch (Fig. 3). The syringe tip is removed and the subject is guided to centric relation, closing the jaws until the central bearing pin lightly contacts the bearing surface of the maxillary clutch. The styli are then depressed with the air control to confirm centric relation (Fig. 4). After the paste hardens and centric relation is confirmed the centric relation pins and reference plane support rod are then placed according to the recommended procedures. The pantographic apparatus can now be removed from the subject's mouth and the clutches can be separated. The zinc-oxide/eugenol paste which has flowed around the central bearing screw prevents the
0022-3913/78/0239-0166500.30/0 9 1978The C. V. MosbyCo.
PROBLEMS IN USING THE DENAR PANTOGRAPH AS A TRANSFER-BOW
Fig. 1. Custom plastic clutches with excess acrylic resin removed leaving only impressions of cusp tips and incisal edges.
Fig. 3. Zinc-oxide/eugenol paste is deposited on the lubricated mandibular clutch. Arrow points to the central bearing screw.
Fig. 2. (A) Rubber-tipped glass syringe with plunger. (B) Disposable plastic syringe. removal of the hardened paste from the mandibular clutch. It can then be noted whether the central bearing pin contacted the central bearing surface (Fig. 5). If it did not the entire procedure should be repeated. The zinc-oxide/eugenol paste lining the toothbearing surface of the maxillary clutch can be trimmed with a sharp scalpel or knife leaving only the cusp tips and incisal edges as indices (Fig. 6). The maxillary cast may then be placed in the clutch and secured using modeling compound or sticky wax. After the mandibular bow is secured to the lower member of the articulator using the mounting platform and either acrylic resin or quick-set artificial stone, the maxillary bow m a y be replaced using the centric pins and the interclutch support as indices. The clutches are joined' with modeling compound or sticky wax and the maxillary cast is mounted to the articulator. The articulator is then set to the pantographic recordings. The pantograph is removed a n d the mandibular cast is mounted to the maxillary cast using an interocclusal centric relation record.
THE JOURNAL OF PROSTHETIC DENTISTRY
Fig. 4. Confirmed centric relation record on the posterior vertical recording platform. DISCUSSION The authors' first attempts at securing accurate pantographic recordings, following the Denar manual, resulted in a movement of the posterior horizontal recording styli away from the centric relation points recorded on the posterior vertical recording tables. It was noted that excessive pressure on the central bearing surface by the subject to keep the clutches firmly attached to the teeth was sufficient to flex the plastic clutches. This minute movement was transmitted to the posterior recording surface resulting in a displacement of the posterior horizontal styli. When zinc-oxide/eugenol paste was used to secure the clutches to the teeth the clutches became rigidly connected to the maxillae and mandible and the subject did not have to clench to keep the clutches in place. Moberg and associates 2 also recognized the displacement of the posterior horizontal styli.
167
BECK, KASS, A N D KNAPP
Fig. 5. Zinc-oxide/eugenol interclutch support. Arrow points to the area where the central bearing screw maintained contact with the central bearing surface of the maxillary clutch.
Fig. 6. The zinc-oxide/eugenoI paste lines the toothbearing surfaces of both clutches. The paste is trimmed with a scalpel leaving only the indentation of cusp tips and incisal edges.
However, their solution of a d j u s t i n g the centric p i n on the side opposite the m o v e m e n t seems too arbit r a r y a n d l i k e l y to i n t r o d u c e error w h e n the corrected position is used to set the articulator. A n interclutch s u p p o r t using stone checkbites between the p a n t o g r a p h i c clutches was then considered.a, 4 Quick-set stone was injected b e t w e e n t h e clutches b u t p r o v e d to be too stiff. T h e resistance to d i s p l a c e m e n t p r o d u c e d either no c o n t a c t b e t w e e n the central b e a r i n g p i n a n d p l a t e o r necessitated too m u c h pressure b y the dentist, w h i c h resulted in t h e same m o v e m e n t as w h e n the subject closed too tightly on the clutches. Z i n c - o x i d e / e u g e n o l p a s t e was then used a n d it p r o v e d to be a successful choice. A d v a n t a g e s of the paste are: (1) It is easy to m a n i p u l a t e ; (2) it offers no resistance to closure a n d causes no d i s p l a c e m e n t o f the posterior h o r i z o n t a l styli; (3) it sets q u i c k l y ; (4) it is d i m e n s i o n a l l y stable; a n d (5) the cost is n o t prohibitive.
D e n a r p a n t o g r a p h is used as a transfer-bow. U s i n g this t e c h n i q u e a stable centric relation position can be m a i n t a i n e d d u r i n g the m a x i l l a r y cast m o u n t i n g p r o c e d u r e a n d the subsequent setting of the articulator to the p a n t o g r a p h i c recordings.
SUMMARY
REFERENCES 1. Guichet, N. F.: Procedures for Occlusal Treatment: A Teaching Atlas. Anaheim, 1969, Denar Corp. 2. Moberg, C. T., Yoder, J. L., and Thayer, K. E.: The pantograph as a face-bow transfer instrument. J PROSTHET DENT 29:139, 1973. 3. Huffman, R. W., and Kegeuos, J. W.: Principles of Occlusion: Laboratory and Clinical Teaching Manual. London, Ohio, 1973, H and R Press. 4. Lucia, V. O.: Modern Gnathological Concepts. St. Louis, 1961, The C. V. Mosby Company. Reprint requests to: DR. DONALD BECK UNIVERSITY OF THE PACIFIC SCHOOL OF DENTISTRY SAN FRANCISCO, CALIF. 9 4 1 1 5
A m e t h o d has been described for using z i n c - o x i d e / eugenol paste a s a n interclutch s u p p o r t w h e n the
168
FEBRUARY 19'/8
VOLUME 39
NUMBER 2
Attempts at utilizing the Denar p a n t o g r a p h t as a transfer-bow, following the instructions in the Denar manual, resulted in a movement of the posterior horizontal styli away from the recorded centric relation position. 1 A method of transferring the Denar pantograph to the Denar D5A articulator using an interclutch support to maintain a stable centric relation is described in this article. PROCEDURE Custom plastic clutches are made for the patient following the technique outlined in the Denar manual. After the acrylic resin sets both clutches are trimmed with a vulcanite bur leaving only the indentations from the cusp tips and incisa] edges (Fig. 1). The central bearing pin surface of the mandibular clutch and the central bearing surface of the maxillary clutch are lubricated with petroleum jelly to facilitate the removal of the interclutch support at a later step. The maxillary clutch is dried with air and the tooth imprints are lined with a zincoxide/eugenol paste.~ The clutch is then seated on the maxillary teeth and held until the paste hardens. The mandibular clutch is inserted with no paste and the central bearing screw is adjusted to provide 0.5 mm clearance between the two clutches throughout all border excursions. The mandibular clutch is removed, dried with air, lined with zinc-oxide/and eugenol paste, and secured to the mandibular teeth. The subject is then instructed to perform the jaw movements needed to obtain pantographic record*Assistant Professor. Department of Fixed Prosthodontics. **Associate Professor and Head of Clinical Fixed Prosthodontics. ***Professorand Director of Occlusion. tDenar Corp., Anaheim, Calif. ~Kerr bite registration paste, Kerr Mfg. Co., Romulus, Mich.
I66
FEBRUARY1978 VOLUME39
NUMBER2
ings. When the movements are mastered the pantograph is-assembled and the recordings obtained according to the prescribed manner. When the tracings are determined to b e acceptable, clear plastic overlays are placed over the recordings to prevent accidental extraneous markings. The maxillary and mandibular bows of the pantograph must then be related to one another to accurately transfer the pantographic apparatus to the articulator. This transfer is one of the most critical steps in the entire pantographic procedure. If the bows of the pantograph are aligned differently on thearticulator than they were on the subject the fidelity of the entire pantographic procedure is lost. The same kind of zinc-oxide/eugenol paste previously used to secure the clutches to the teeth is also used for the interclutch support. The paste is mixed and placed in either a glass cylinder syringe, which has a soft, flexible rubber tip, or in a disposable plastic syringe (Fig. 2). The subject is instructed to open the jaws sufficiently to allow for the insertion of the syringe tip, and the paste is then injected onto the lubricated surface of the mandibular clutch (Fig. 3). The syringe tip is removed and the subject is guided to centric relation, closing the jaws until the central bearing pin lightly contacts the bearing surface of the maxillary clutch. The styli are then depressed with the air control to confirm centric relation (Fig. 4). After the paste hardens and centric relation is confirmed the centric relation pins and reference plane support rod are then placed according to the recommended procedures. The pantographic apparatus can now be removed from the subject's mouth and the clutches can be separated. The zinc-oxide/eugenol paste which has flowed around the central bearing screw prevents the
0022-3913/78/0239-0166500.30/0 9 1978The C. V. MosbyCo.
PROBLEMS IN USING THE DENAR PANTOGRAPH AS A TRANSFER-BOW
Fig. 1. Custom plastic clutches with excess acrylic resin removed leaving only impressions of cusp tips and incisal edges.
Fig. 3. Zinc-oxide/eugenol paste is deposited on the lubricated mandibular clutch. Arrow points to the central bearing screw.
Fig. 2. (A) Rubber-tipped glass syringe with plunger. (B) Disposable plastic syringe. removal of the hardened paste from the mandibular clutch. It can then be noted whether the central bearing pin contacted the central bearing surface (Fig. 5). If it did not the entire procedure should be repeated. The zinc-oxide/eugenol paste lining the toothbearing surface of the maxillary clutch can be trimmed with a sharp scalpel or knife leaving only the cusp tips and incisal edges as indices (Fig. 6). The maxillary cast may then be placed in the clutch and secured using modeling compound or sticky wax. After the mandibular bow is secured to the lower member of the articulator using the mounting platform and either acrylic resin or quick-set artificial stone, the maxillary bow m a y be replaced using the centric pins and the interclutch support as indices. The clutches are joined' with modeling compound or sticky wax and the maxillary cast is mounted to the articulator. The articulator is then set to the pantographic recordings. The pantograph is removed a n d the mandibular cast is mounted to the maxillary cast using an interocclusal centric relation record.
THE JOURNAL OF PROSTHETIC DENTISTRY
Fig. 4. Confirmed centric relation record on the posterior vertical recording platform. DISCUSSION The authors' first attempts at securing accurate pantographic recordings, following the Denar manual, resulted in a movement of the posterior horizontal recording styli away from the centric relation points recorded on the posterior vertical recording tables. It was noted that excessive pressure on the central bearing surface by the subject to keep the clutches firmly attached to the teeth was sufficient to flex the plastic clutches. This minute movement was transmitted to the posterior recording surface resulting in a displacement of the posterior horizontal styli. When zinc-oxide/eugenol paste was used to secure the clutches to the teeth the clutches became rigidly connected to the maxillae and mandible and the subject did not have to clench to keep the clutches in place. Moberg and associates 2 also recognized the displacement of the posterior horizontal styli.
167
BECK, KASS, A N D KNAPP
Fig. 5. Zinc-oxide/eugenol interclutch support. Arrow points to the area where the central bearing screw maintained contact with the central bearing surface of the maxillary clutch.
Fig. 6. The zinc-oxide/eugenoI paste lines the toothbearing surfaces of both clutches. The paste is trimmed with a scalpel leaving only the indentation of cusp tips and incisal edges.
However, their solution of a d j u s t i n g the centric p i n on the side opposite the m o v e m e n t seems too arbit r a r y a n d l i k e l y to i n t r o d u c e error w h e n the corrected position is used to set the articulator. A n interclutch s u p p o r t using stone checkbites between the p a n t o g r a p h i c clutches was then considered.a, 4 Quick-set stone was injected b e t w e e n t h e clutches b u t p r o v e d to be too stiff. T h e resistance to d i s p l a c e m e n t p r o d u c e d either no c o n t a c t b e t w e e n the central b e a r i n g p i n a n d p l a t e o r necessitated too m u c h pressure b y the dentist, w h i c h resulted in t h e same m o v e m e n t as w h e n the subject closed too tightly on the clutches. Z i n c - o x i d e / e u g e n o l p a s t e was then used a n d it p r o v e d to be a successful choice. A d v a n t a g e s of the paste are: (1) It is easy to m a n i p u l a t e ; (2) it offers no resistance to closure a n d causes no d i s p l a c e m e n t o f the posterior h o r i z o n t a l styli; (3) it sets q u i c k l y ; (4) it is d i m e n s i o n a l l y stable; a n d (5) the cost is n o t prohibitive.
D e n a r p a n t o g r a p h is used as a transfer-bow. U s i n g this t e c h n i q u e a stable centric relation position can be m a i n t a i n e d d u r i n g the m a x i l l a r y cast m o u n t i n g p r o c e d u r e a n d the subsequent setting of the articulator to the p a n t o g r a p h i c recordings.
SUMMARY
REFERENCES 1. Guichet, N. F.: Procedures for Occlusal Treatment: A Teaching Atlas. Anaheim, 1969, Denar Corp. 2. Moberg, C. T., Yoder, J. L., and Thayer, K. E.: The pantograph as a face-bow transfer instrument. J PROSTHET DENT 29:139, 1973. 3. Huffman, R. W., and Kegeuos, J. W.: Principles of Occlusion: Laboratory and Clinical Teaching Manual. London, Ohio, 1973, H and R Press. 4. Lucia, V. O.: Modern Gnathological Concepts. St. Louis, 1961, The C. V. Mosby Company. Reprint requests to: DR. DONALD BECK UNIVERSITY OF THE PACIFIC SCHOOL OF DENTISTRY SAN FRANCISCO, CALIF. 9 4 1 1 5
A m e t h o d has been described for using z i n c - o x i d e / eugenol paste a s a n interclutch s u p p o r t w h e n the
168
FEBRUARY 19'/8
VOLUME 39
NUMBER 2