SECTION E D I T O R
D i r e c t p o s t and c o r e p a t t e r n m a d e w i t h l i g h t - c u r i n g composite resin S. M. C o h e n , D . D . S . , M.S.,* J. V a i d y a n a t h a n , Ph.D.,* a n d R. C. H a e b e r l e , D.M.D.**
University of Medicine and Dentistry of New Jersey, New Jersey Dental School, Newark, N.J. An unfilled Bis-GMA composite resin can be used a d v a n t a g e o u s l y for m a k i n g an accurate cast post and core pattern. The technique is f a s t e r and e a s i e r than normal pattern fabrication methods using an unfilled acrylic resin, wax, or a combination of the two. (J PROSTHET DENT 1991;65:854-6.)
T h e parallel-sided cast dowel and core remains an excellent treatment choice for nonvital anterior restorations with little or no residual coronal tooth structure and/ or when heavy functional stresses are anticipated. 1"3 The conventional method of direct pattern fabrication involves using an autocuring acrylic resin, a type I inlay wax, or both. 46 In addition, a clear resin matrix made on an appropriately altered diagnostic cast can be used to facilitate the overall procedure, especially when multiple patterns are planned. 2 This article presents a simplified technique that uses an unfilled light-curing Bis-GMA composite resin for the core fabrication (the resin must be unfilled to ensure complete burnout). The primary advantage of this method is that
since the material is light-cured, the dentist is in complete control of the setting time and therefore can carefully shape the pattern prior to curing. In addition, the curing time is much faster than with an all acrylic resin build-up.
*Assistant Professor, Department of Prosthodontics and Biomaterials. **Clinical Associate Professor, Department of Prosthodontics and Biomaterials. 10/1/27545
Fig. 2. Para-Post dowels in place cut to proper length.
Fig. 1. Post preparations with oval orifices.
Fig. 3. Orifice filled with Duralay resin.
854
J U N E 1991
VOLUME 65
NUMBER 6
U N F I L L E D COMPOSITE RESIN BURNOUT PATTERNS
Fig. 4. Clear plastic matrices made over preparations (A); full contour (B).
Fig. 5. Completed composite resin pattern build-up. A, Facial; B, lingual.
The dentist has the choice of either making the pattern freehand incrementally or constructing a clear matrix of either ideal preparations or the teeth restored to full contour. In the latter instance, the composite resin pattern can be easily finished intraorally using normal rotary instrumentation with water spray. PROCEDURE 1. Prepare the coronal segments in the normal manner. Make the orifice oval-shaped to aid in resisting rotational forces (Fig. 1). 2. Remove the gutta-percha canal obturation using a combination of warm endodontic pluggers, Peeso reamers (Union Broach Co., Inc., Long Island City, N.Y.) in proper sequence and Para-Post (Whaledent International, New York, N.Y.) color-coded drills. Leave a minimum of 3 to 5 mm apical seal in all teeth. 3. Select and fit to the canal an 0.040 or 0.050 plastic color-coded Para-Post burnout pattern (corresponding to the largest drill size used). Adjust the length to allow sufficient extension coronally to retain the build-up material (Fig. 2). 4. Lightly lubricate the preparation and carefully introduce Duralay (Reliance Dental Manufacturing Co., Chicago, Ill.) into the widened orifice of the canal using
THE J O U R N A L OF P R O S T H E T I C D E N T I S T R Y
Fig. 6. Completed castings. A, Facial; B, lingual.
855
COHEN, VAIDYANATHAN, AND HAEBERLE
a brush with the powder/liquid technique. When the resin has polymerized, remove the post portion, examine it for voids, stability, and accuracy, and modify it as required (Fig. 3). 5. When the post fits accurately, build-up the core portion incrementally using unfilled composite resin (ICI Dental, London, England). The pattern is easy to shape due to the favorable viscosity of the material. If desired, a clear plastic matrix (Buffalo Dental Mfg. Co., Inc., Syosset, N.Y.) may be made of either idealized preparations or to full contour on a previously prepared diagnostic cast (Fig. 4). 6. Trim the patterns and finish as required (Fig. 5). Usually little adjustment is necessary with the free-hand method or by using a matrix of ideal preparations. If a full contour matrix is used, the preparations can be easily finished with ordinary composite resin rotary instrumentation, sandpaper disks, and polishing compound. 7. Invest and cast the patterns. Finish, adjust, and cement
them in the usual manner (Fig. 6). Ordinarily, only minor adjustments will be required. REFERENCES
1. Eissman HF, Rudd KD, MorrowRM. Dental laboratory procedures: fixed partial dentures, vol 2. St Louis:The CV MosbyCo, 1980:18-27. 2. FehlingAT, WolfertRE. Multiple castpost and coresfor anterior teeth: rationale and technique. J PROSTHETDENT1988;59:558-62. 3. Sorensen JA, Martinoff JT. Clinically significant factors in dowel design. J PROSTHETDENT1982;52:28-34. 4. ShillingburgHT, Hobo S, Whitsett LD. Fundamentals of fixed prosthodontics, Chicago:Quintessence Publishing Co, 1981:147-54. 5. MillerAWIII. Directpattern techniquefor posts and cores.J PROSTHET DENT 1978;40:392-7. 6. Christensen LC. Plastic dowel a n d core systems. J PROSTHgr DENT 1988;60:673-5.
Reprint requests to: DR. STEPHEN M. COHEN NEW JERSEY DENTAL SCHOOL UNIVERSITY OF MEDICINE AND DENTISTRY 110 BERGEN ST. NEWARK, N J 07103-2425
Film t h i c k n e s s of four d i s c l o s i n g m e d i a G. R o g e r T r o e n d l e , M.S., D.D.S.,* K a r e n B. T r o e n d l e , D.D.S.,** a n d E d m u n d C a v a z o s , Jr., D.D.S.**
University of Texas Health Science Center, Dental School, San Antonio, Tex. The use of disclosing media has been r e c o m m e n d e d to enhance the fit of castings. This study e v a l u a t e d the film t h i c k n e s s of four disclosing media: (1) disclosing wax, (2) Net spray, (3) G-C Check Fit material, and (4) Extrude p o l y v i n y l s i l o x a n e (low viscosity) i m p r e s s i o n material. A D A Specification No. 8 for zinc phosphate c e m e n t g i v e s a m a x i m u m film t h i c k n e s s for the c e m e n t that w a s used as the control for t h e s e four media. The results demonstrated that the film t h i c k n e s s e s of all four disclosing media w e r e less than the 25 ~m m a x i m u m a l l o w e d for zinc phosphate cement. (J PROSTHET DENT 1991;65:856-7.)
O n e of the most frustrating experiences clinically is to have a casting that will not seat properly on the prepared tooth. Several causes can be related to many different stages of the restorative procedure. Some of these causes are (1) improper line of draw with adjacent teeth, (2) undercut in the preparations, (3) distorted impressions, (4) abraded dies, (5) overextended wax patterns, (6) distorted wax patterns, (7) improper expansion of the investment,
*Clinical Associate Professor, Department of Restorative Dentistry. **Associate Professor, Department of Restorative Dentistry. 10/1/27542
856
(8) improper burnout technique, (9) nodules on the casting, (10) distorted casting, or (11) excessive proximal contacts. A number of materials have been suggested to disclose discrepancies of fit between the casting and the prepared t o o t h . l , 2 Although none of these materials can be used to make a grossly ill-fitting casting adapt to a preparation, they can be used to refine the internal adaptation of a casting that is nearly seated. These minor discrepancies in internal adaptations usually manifest themselves as minor discrepancies in marginal adaptations. Materials often used to disclose discrepancies in internal adaptation include (1) disclosing wax, (2) Ney spray, and (3) G-C Check Fit. Another possible disclosing medium available in many offices is low-viscosity polyvinylsiloxane impression material. 3
J U N E 1991
VOLUME 65 NUMBER 6
D i r e c t p o s t and c o r e p a t t e r n m a d e w i t h l i g h t - c u r i n g composite resin S. M. C o h e n , D . D . S . , M.S.,* J. V a i d y a n a t h a n , Ph.D.,* a n d R. C. H a e b e r l e , D.M.D.**
University of Medicine and Dentistry of New Jersey, New Jersey Dental School, Newark, N.J. An unfilled Bis-GMA composite resin can be used a d v a n t a g e o u s l y for m a k i n g an accurate cast post and core pattern. The technique is f a s t e r and e a s i e r than normal pattern fabrication methods using an unfilled acrylic resin, wax, or a combination of the two. (J PROSTHET DENT 1991;65:854-6.)
T h e parallel-sided cast dowel and core remains an excellent treatment choice for nonvital anterior restorations with little or no residual coronal tooth structure and/ or when heavy functional stresses are anticipated. 1"3 The conventional method of direct pattern fabrication involves using an autocuring acrylic resin, a type I inlay wax, or both. 46 In addition, a clear resin matrix made on an appropriately altered diagnostic cast can be used to facilitate the overall procedure, especially when multiple patterns are planned. 2 This article presents a simplified technique that uses an unfilled light-curing Bis-GMA composite resin for the core fabrication (the resin must be unfilled to ensure complete burnout). The primary advantage of this method is that
since the material is light-cured, the dentist is in complete control of the setting time and therefore can carefully shape the pattern prior to curing. In addition, the curing time is much faster than with an all acrylic resin build-up.
*Assistant Professor, Department of Prosthodontics and Biomaterials. **Clinical Associate Professor, Department of Prosthodontics and Biomaterials. 10/1/27545
Fig. 2. Para-Post dowels in place cut to proper length.
Fig. 1. Post preparations with oval orifices.
Fig. 3. Orifice filled with Duralay resin.
854
J U N E 1991
VOLUME 65
NUMBER 6
U N F I L L E D COMPOSITE RESIN BURNOUT PATTERNS
Fig. 4. Clear plastic matrices made over preparations (A); full contour (B).
Fig. 5. Completed composite resin pattern build-up. A, Facial; B, lingual.
The dentist has the choice of either making the pattern freehand incrementally or constructing a clear matrix of either ideal preparations or the teeth restored to full contour. In the latter instance, the composite resin pattern can be easily finished intraorally using normal rotary instrumentation with water spray. PROCEDURE 1. Prepare the coronal segments in the normal manner. Make the orifice oval-shaped to aid in resisting rotational forces (Fig. 1). 2. Remove the gutta-percha canal obturation using a combination of warm endodontic pluggers, Peeso reamers (Union Broach Co., Inc., Long Island City, N.Y.) in proper sequence and Para-Post (Whaledent International, New York, N.Y.) color-coded drills. Leave a minimum of 3 to 5 mm apical seal in all teeth. 3. Select and fit to the canal an 0.040 or 0.050 plastic color-coded Para-Post burnout pattern (corresponding to the largest drill size used). Adjust the length to allow sufficient extension coronally to retain the build-up material (Fig. 2). 4. Lightly lubricate the preparation and carefully introduce Duralay (Reliance Dental Manufacturing Co., Chicago, Ill.) into the widened orifice of the canal using
THE J O U R N A L OF P R O S T H E T I C D E N T I S T R Y
Fig. 6. Completed castings. A, Facial; B, lingual.
855
COHEN, VAIDYANATHAN, AND HAEBERLE
a brush with the powder/liquid technique. When the resin has polymerized, remove the post portion, examine it for voids, stability, and accuracy, and modify it as required (Fig. 3). 5. When the post fits accurately, build-up the core portion incrementally using unfilled composite resin (ICI Dental, London, England). The pattern is easy to shape due to the favorable viscosity of the material. If desired, a clear plastic matrix (Buffalo Dental Mfg. Co., Inc., Syosset, N.Y.) may be made of either idealized preparations or to full contour on a previously prepared diagnostic cast (Fig. 4). 6. Trim the patterns and finish as required (Fig. 5). Usually little adjustment is necessary with the free-hand method or by using a matrix of ideal preparations. If a full contour matrix is used, the preparations can be easily finished with ordinary composite resin rotary instrumentation, sandpaper disks, and polishing compound. 7. Invest and cast the patterns. Finish, adjust, and cement
them in the usual manner (Fig. 6). Ordinarily, only minor adjustments will be required. REFERENCES
1. Eissman HF, Rudd KD, MorrowRM. Dental laboratory procedures: fixed partial dentures, vol 2. St Louis:The CV MosbyCo, 1980:18-27. 2. FehlingAT, WolfertRE. Multiple castpost and coresfor anterior teeth: rationale and technique. J PROSTHETDENT1988;59:558-62. 3. Sorensen JA, Martinoff JT. Clinically significant factors in dowel design. J PROSTHETDENT1982;52:28-34. 4. ShillingburgHT, Hobo S, Whitsett LD. Fundamentals of fixed prosthodontics, Chicago:Quintessence Publishing Co, 1981:147-54. 5. MillerAWIII. Directpattern techniquefor posts and cores.J PROSTHET DENT 1978;40:392-7. 6. Christensen LC. Plastic dowel a n d core systems. J PROSTHgr DENT 1988;60:673-5.
Reprint requests to: DR. STEPHEN M. COHEN NEW JERSEY DENTAL SCHOOL UNIVERSITY OF MEDICINE AND DENTISTRY 110 BERGEN ST. NEWARK, N J 07103-2425
Film t h i c k n e s s of four d i s c l o s i n g m e d i a G. R o g e r T r o e n d l e , M.S., D.D.S.,* K a r e n B. T r o e n d l e , D.D.S.,** a n d E d m u n d C a v a z o s , Jr., D.D.S.**
University of Texas Health Science Center, Dental School, San Antonio, Tex. The use of disclosing media has been r e c o m m e n d e d to enhance the fit of castings. This study e v a l u a t e d the film t h i c k n e s s of four disclosing media: (1) disclosing wax, (2) Net spray, (3) G-C Check Fit material, and (4) Extrude p o l y v i n y l s i l o x a n e (low viscosity) i m p r e s s i o n material. A D A Specification No. 8 for zinc phosphate c e m e n t g i v e s a m a x i m u m film t h i c k n e s s for the c e m e n t that w a s used as the control for t h e s e four media. The results demonstrated that the film t h i c k n e s s e s of all four disclosing media w e r e less than the 25 ~m m a x i m u m a l l o w e d for zinc phosphate cement. (J PROSTHET DENT 1991;65:856-7.)
O n e of the most frustrating experiences clinically is to have a casting that will not seat properly on the prepared tooth. Several causes can be related to many different stages of the restorative procedure. Some of these causes are (1) improper line of draw with adjacent teeth, (2) undercut in the preparations, (3) distorted impressions, (4) abraded dies, (5) overextended wax patterns, (6) distorted wax patterns, (7) improper expansion of the investment,
*Clinical Associate Professor, Department of Restorative Dentistry. **Associate Professor, Department of Restorative Dentistry. 10/1/27542
856
(8) improper burnout technique, (9) nodules on the casting, (10) distorted casting, or (11) excessive proximal contacts. A number of materials have been suggested to disclose discrepancies of fit between the casting and the prepared t o o t h . l , 2 Although none of these materials can be used to make a grossly ill-fitting casting adapt to a preparation, they can be used to refine the internal adaptation of a casting that is nearly seated. These minor discrepancies in internal adaptations usually manifest themselves as minor discrepancies in marginal adaptations. Materials often used to disclose discrepancies in internal adaptation include (1) disclosing wax, (2) Ney spray, and (3) G-C Check Fit. Another possible disclosing medium available in many offices is low-viscosity polyvinylsiloxane impression material. 3
J U N E 1991
VOLUME 65 NUMBER 6
