- Email: [email protected]
Laminated single impression technique for cast posts and cores
PREFABRICATED
POST
STRENGTH
then learn to place posts with optimal torque through technique courses.
3.
SUMMARY
4.
Thirty-one dentists were tested relative to the optimal and maximum amount of torque they could deliver to posts in teeth. The mean for the optimal amount of torque was 15.55 ounce-inches, and the mean for the maximum amount of torque was 35.29 ounce-inches. Female dentists showed a statistically significantly lower mean difference of 24.5 ounce-inches on the maximum torque test.
5. 6.
7.
8.
REFERENCES 1.
2.
Guzy, G. E., and Nicholls, J. I.: In vitro comparison of intact endodontically treated teeth with and without endo-post reinforcement. J PROSTHET DENT 4239, 1979. Trabert, K. C., Caputo, A. A., and Abou-Ross, M.: Tooth fracture-A comparison of endodontic and restorative treatments. J Endodont 4~341, 1978.
Laminated and cores
G. Mikhail,
Louisiana
New
State
Reprint requests to: DR. ALLAN
University,
School
of Dentistry,
Orleans,
S. DEUTSCH
119 WEST 57~~ NEW YORK, NY
single impression
Gerard J. Chiche, D.C.D.,+ and Mongi
Standlee, J. P., Caputo, A. A., Collard, E. W., and Pollack, J. H.: Analysis of stress distribution by endodontic posts. Oral Surg 33~952, 1972. Kurer, H. G., Combe, E. C., and Grant, A. A.: Factors influencing the retention of dowels. J PROSTHET DENT 38:515, 1977. Newburg, R. E., and Pameijer, C. H.: Retentive properties of post and core systems. J PROSTHET DENT 36:636, 1976. Standlee, J. P., Caputo, A. A., Holcomb, J., and Trabert, K. C.: The retentive and stress-distributing properties of a threaded endodontic dowel. J PROSTHET DENT 44~398, 1980. Standlee, J. P., Caputo, A. A., and Hanson, E. C.: Retention of endodontic dowels: Effects of cement, dowel length, diameter and design. J PROSTHET DENT 39~401, 1978. Snedecor, G. W., and Cochran, W. G.: Statistical Methods. Ames, Iowa, The Iowa University Press.
ST., STE. 700 10019
technique
for cast posts
B.D.S., M.Sc.** La.
S
ilicone rubber impression materials enjoy wide acceptance. Their advantages include ease of use, no custom tray, and readily discernible finish lines.’ The laminated single impression technique is an alternative to the conventional two-step procedure involved in the putty-light system.2 Fusayama et a1.3reported the laminated single impression technique to be dimensionally accurate in a laboratory experiment. This article describes the laminated impression procedure for indirect cast post and core fabrication.
METHODS Preparation of a single canal for a prefabricated burnout post 1. Shape the canal to a final configuration with the appropriate rotary drill. 2. Insert the matching size post. Slight friction must be felt on removal. 3. Check the completed preparation; adequate
*Assistant **Associate THE
Professor, Department Professor, Department
JOURNAL
OF PROSTHETIC
of Crown and Bridge. of Crown and Bridge. DENTISTRY
Fig. 1. Post extends at least 5 mm above tooth prepara-
tion.
remaining dentin is protected with a bevel, an antirotakeyway placed, and margins clearly delineated.’ 4. Ensure that the post end extends at least 5 mm above the coronal aspect of the preparation to provide adequate retention in the putty material (Fig. 1). 5. Apply silicone adhesive to the portion of the post
tion
325
CHICHE
Fig. 2. Materials dispensed prior to mixing.
Fig. 3. Completed impression with smooth blending of putty and light materials.
Fig. 4. Fine reproduction
of details.
Fig.
AND
MIKHAIL
5. Initial post and core try-in.
Fig. 6. Two-piece casting of divergent
canal prepara-
tions.
Fig. 7. Two diverging
prefabricated posts are incorpo-
rated in the impression. that protrudes from the canal and to the appropriate size perforated stock impression tray. 6. Position the post in the canal. 7. Dispense light-bodied and putty materials (Optosil and Xantoprene, Unitek Co., Monrovia, Calif.) onto two separate pads with the specified amount of catalyst for each material (Fig. 2). 326
8. Mix the light-body material and load the syringe. While the material is being injected by the dentist, the dental assistant will mix the putty material and load the stock tray. 9. Slowly inject the light-body material around the intracoronal portion of the post. A gentle stream of air helps minimize air entrapment. MARCH
1985
VOLUME
53
NUMBER
3
IMPRESSION
TECHNIQUE
Fig. 8. Two-piece
FOR POSTS
casting
AND
CORES
after cementation.
Fig. 11. Customized technique for overdenture abutments. Light material was injected in the retracted gingival sulcus and inside each canal. Note how it encircles each post.
Fig. 12. Copings ture. Fig. 9. Contact between post extremities before light material is injected.
for
castings,
10. Insert the stock tray firmly until it is fully seated. The putty material should extrude through the tray perforations. 11. After the recommended setting time has elapsed, remove the impression with a bold, snap-like motion,4 THE
JOURNAL
OF PROSTHETIC
DENTISTRY
maxillary
den-
is checked
Fig. 13. Copings
Fig. 10. Cemented
tooth-supported
cemented
into position.
blow the impression dry, and carefully inspect it. Putty and light materials should be smoothly blended (Fig: 3). 12. Pour the cast immediately with the use of a wetting agent. Prepare the master cast (Fig. 4). 13. Fabricate the wax pattern incorporating the same burnout post. Invest and cast with minimum expansion to avoid possible binding in the canal. 327
CHICHE
Modifications
to the previous
AND
MIKHAII
techniques
1. A loosely fitting plastic post that engages the whole length of the canal preparation is used as support. 2. The entire post is coated with adhesive. 3. The canal preparation is lubricated. 4. The light-body material is injected into the canal as far as possible (a spiral drill is helpful). 5. The post is gently tapped into place after the canal has been slightly overfilled. The post reaches a secure position when it does not rebound from the apical portion of the preparation.
SUMMARY Fig. 14. Combination of prefabricated and customized indirect cast post and core fabrication helps reduce chairside procedures for reconstruction. 14. Adjust the casting on the master cast until adequate seating is obtained. This reduces or eliminates chairside adjustments (Fig. 5).
Preparation posts
of multiple
canals for prefabricated
Due to the elastic recovery of silicone rubber materiais,5 the impression of multiple divergent canal preparations is dimensionally stable (Figs. 6 to 8).
Additional
precautions
1. Avoid tight contact between converging post ends within the same tooth. Bending of the post and distortion of the impression will occur (Figs. 9 and 10). 2. Leave the impression in the mouth 5 minutes beyond the recommended setting time. This will ensure that the optimal elastic properties are retained.6
Customized canals
technique
for single or multiple
The light-bodied material is injected to the apical end of the canal preparation and adequately supported throughout its entire length (Figs. 11 to 13).
328
A laminated single impression technique for cast post and core has been described. Its advantages are the ease and versatility with prefabricated or customized post techniques (Fig. 14) and the one-step registration of single or multiple divergent canals. Its disadvantage is the necessity for additional laboratory procedures. REFERENCES Shillingburg, Jr., H. T., Hobo, S., and Whitsett, L. D.: Fundamentals of Fixed Prosthodontics, ed 2. Chicago, 1981, Quintessence Publishing Co. Inc. Fusayama, T., Iwaku, N., Daito, K., Kurosaki, N., Takatsu, T., and Yamane, M.: The procedure of the laminated single impression technique with silicone materials. Nikon Shika Hyoron 337~70, 1974. Fusayama, T., Iwaku, M., Kurosaki, N., and Takatsu, T.: Accuracy of the laminated single impression technique. J PROSTHET DENT 32:270, 1974. Craig, R. G.: Dental Materials: A Problem Oriented Approach. St. Louis, 1978, The C. V. Mosby Co. O’Brien, W. J., and Ryge, G.: An Outline of Dental Materials and Their Selection. Philadelphia, 1978, W. B. Saunders Co. Phillips, R. W.: Science of Dental Materials, ed 8. Philadelphia, 1982, W. B. Saunders Co.
Reprmt requests to: DR. G. J. CHICHE LOUISIANA STATE UNIVERSITY SCHOLL OF DENTISTRY NEW ORLEANS,
LA 70119
MARCH
1985
VOLUME
53
NUMBER
3
POST
STRENGTH
then learn to place posts with optimal torque through technique courses.
3.
SUMMARY
4.
Thirty-one dentists were tested relative to the optimal and maximum amount of torque they could deliver to posts in teeth. The mean for the optimal amount of torque was 15.55 ounce-inches, and the mean for the maximum amount of torque was 35.29 ounce-inches. Female dentists showed a statistically significantly lower mean difference of 24.5 ounce-inches on the maximum torque test.
5. 6.
7.
8.
REFERENCES 1.
2.
Guzy, G. E., and Nicholls, J. I.: In vitro comparison of intact endodontically treated teeth with and without endo-post reinforcement. J PROSTHET DENT 4239, 1979. Trabert, K. C., Caputo, A. A., and Abou-Ross, M.: Tooth fracture-A comparison of endodontic and restorative treatments. J Endodont 4~341, 1978.
Laminated and cores
G. Mikhail,
Louisiana
New
State
Reprint requests to: DR. ALLAN
University,
School
of Dentistry,
Orleans,
S. DEUTSCH
119 WEST 57~~ NEW YORK, NY
single impression
Gerard J. Chiche, D.C.D.,+ and Mongi
Standlee, J. P., Caputo, A. A., Collard, E. W., and Pollack, J. H.: Analysis of stress distribution by endodontic posts. Oral Surg 33~952, 1972. Kurer, H. G., Combe, E. C., and Grant, A. A.: Factors influencing the retention of dowels. J PROSTHET DENT 38:515, 1977. Newburg, R. E., and Pameijer, C. H.: Retentive properties of post and core systems. J PROSTHET DENT 36:636, 1976. Standlee, J. P., Caputo, A. A., Holcomb, J., and Trabert, K. C.: The retentive and stress-distributing properties of a threaded endodontic dowel. J PROSTHET DENT 44~398, 1980. Standlee, J. P., Caputo, A. A., and Hanson, E. C.: Retention of endodontic dowels: Effects of cement, dowel length, diameter and design. J PROSTHET DENT 39~401, 1978. Snedecor, G. W., and Cochran, W. G.: Statistical Methods. Ames, Iowa, The Iowa University Press.
ST., STE. 700 10019
technique
for cast posts
B.D.S., M.Sc.** La.
S
ilicone rubber impression materials enjoy wide acceptance. Their advantages include ease of use, no custom tray, and readily discernible finish lines.’ The laminated single impression technique is an alternative to the conventional two-step procedure involved in the putty-light system.2 Fusayama et a1.3reported the laminated single impression technique to be dimensionally accurate in a laboratory experiment. This article describes the laminated impression procedure for indirect cast post and core fabrication.
METHODS Preparation of a single canal for a prefabricated burnout post 1. Shape the canal to a final configuration with the appropriate rotary drill. 2. Insert the matching size post. Slight friction must be felt on removal. 3. Check the completed preparation; adequate
*Assistant **Associate THE
Professor, Department Professor, Department
JOURNAL
OF PROSTHETIC
of Crown and Bridge. of Crown and Bridge. DENTISTRY
Fig. 1. Post extends at least 5 mm above tooth prepara-
tion.
remaining dentin is protected with a bevel, an antirotakeyway placed, and margins clearly delineated.’ 4. Ensure that the post end extends at least 5 mm above the coronal aspect of the preparation to provide adequate retention in the putty material (Fig. 1). 5. Apply silicone adhesive to the portion of the post
tion
325
CHICHE
Fig. 2. Materials dispensed prior to mixing.
Fig. 3. Completed impression with smooth blending of putty and light materials.
Fig. 4. Fine reproduction
of details.
Fig.
AND
MIKHAIL
5. Initial post and core try-in.
Fig. 6. Two-piece casting of divergent
canal prepara-
tions.
Fig. 7. Two diverging
prefabricated posts are incorpo-
rated in the impression. that protrudes from the canal and to the appropriate size perforated stock impression tray. 6. Position the post in the canal. 7. Dispense light-bodied and putty materials (Optosil and Xantoprene, Unitek Co., Monrovia, Calif.) onto two separate pads with the specified amount of catalyst for each material (Fig. 2). 326
8. Mix the light-body material and load the syringe. While the material is being injected by the dentist, the dental assistant will mix the putty material and load the stock tray. 9. Slowly inject the light-body material around the intracoronal portion of the post. A gentle stream of air helps minimize air entrapment. MARCH
1985
VOLUME
53
NUMBER
3
IMPRESSION
TECHNIQUE
Fig. 8. Two-piece
FOR POSTS
casting
AND
CORES
after cementation.
Fig. 11. Customized technique for overdenture abutments. Light material was injected in the retracted gingival sulcus and inside each canal. Note how it encircles each post.
Fig. 12. Copings ture. Fig. 9. Contact between post extremities before light material is injected.
for
castings,
10. Insert the stock tray firmly until it is fully seated. The putty material should extrude through the tray perforations. 11. After the recommended setting time has elapsed, remove the impression with a bold, snap-like motion,4 THE
JOURNAL
OF PROSTHETIC
DENTISTRY
maxillary
den-
is checked
Fig. 13. Copings
Fig. 10. Cemented
tooth-supported
cemented
into position.
blow the impression dry, and carefully inspect it. Putty and light materials should be smoothly blended (Fig: 3). 12. Pour the cast immediately with the use of a wetting agent. Prepare the master cast (Fig. 4). 13. Fabricate the wax pattern incorporating the same burnout post. Invest and cast with minimum expansion to avoid possible binding in the canal. 327
CHICHE
Modifications
to the previous
AND
MIKHAII
techniques
1. A loosely fitting plastic post that engages the whole length of the canal preparation is used as support. 2. The entire post is coated with adhesive. 3. The canal preparation is lubricated. 4. The light-body material is injected into the canal as far as possible (a spiral drill is helpful). 5. The post is gently tapped into place after the canal has been slightly overfilled. The post reaches a secure position when it does not rebound from the apical portion of the preparation.
SUMMARY Fig. 14. Combination of prefabricated and customized indirect cast post and core fabrication helps reduce chairside procedures for reconstruction. 14. Adjust the casting on the master cast until adequate seating is obtained. This reduces or eliminates chairside adjustments (Fig. 5).
Preparation posts
of multiple
canals for prefabricated
Due to the elastic recovery of silicone rubber materiais,5 the impression of multiple divergent canal preparations is dimensionally stable (Figs. 6 to 8).
Additional
precautions
1. Avoid tight contact between converging post ends within the same tooth. Bending of the post and distortion of the impression will occur (Figs. 9 and 10). 2. Leave the impression in the mouth 5 minutes beyond the recommended setting time. This will ensure that the optimal elastic properties are retained.6
Customized canals
technique
for single or multiple
The light-bodied material is injected to the apical end of the canal preparation and adequately supported throughout its entire length (Figs. 11 to 13).
328
A laminated single impression technique for cast post and core has been described. Its advantages are the ease and versatility with prefabricated or customized post techniques (Fig. 14) and the one-step registration of single or multiple divergent canals. Its disadvantage is the necessity for additional laboratory procedures. REFERENCES Shillingburg, Jr., H. T., Hobo, S., and Whitsett, L. D.: Fundamentals of Fixed Prosthodontics, ed 2. Chicago, 1981, Quintessence Publishing Co. Inc. Fusayama, T., Iwaku, N., Daito, K., Kurosaki, N., Takatsu, T., and Yamane, M.: The procedure of the laminated single impression technique with silicone materials. Nikon Shika Hyoron 337~70, 1974. Fusayama, T., Iwaku, M., Kurosaki, N., and Takatsu, T.: Accuracy of the laminated single impression technique. J PROSTHET DENT 32:270, 1974. Craig, R. G.: Dental Materials: A Problem Oriented Approach. St. Louis, 1978, The C. V. Mosby Co. O’Brien, W. J., and Ryge, G.: An Outline of Dental Materials and Their Selection. Philadelphia, 1978, W. B. Saunders Co. Phillips, R. W.: Science of Dental Materials, ed 8. Philadelphia, 1982, W. B. Saunders Co.
Reprmt requests to: DR. G. J. CHICHE LOUISIANA STATE UNIVERSITY SCHOLL OF DENTISTRY NEW ORLEANS,
LA 70119
MARCH
1985
VOLUME
53
NUMBER
3