- Email: [email protected]
A new device to directly examine parallelism of abutment teeth
COMPARISONOFMARGINALFIT
10. Eden GT, Franklin OM, Powel JM, Ohta Y, Dickson G. Fit of porcelainfused-to-metal crown and bridge castings. J Dent Res 1979;58:2360-79. 11. Hunt JL, Cruikshanks-Boyd DW, Davies EH. The marginal characteristics of collarless bonded porcelain crowns produced using a separating medium technique. Quintessence Dent Technol1978;9:21. 12. DeHoff PH. Anusavice HJ, Boyce RJ. Analysis of thermally induced stresses in porcelain metal systems. J Dent Res 1983;62:593-7. 13. Bridger DV, Nicholls JI. Distortion of ceramometal fixed partial dentures during the firing cycle. J PROSTHET DENT 1961;45:507-14. 14. Buchanan WT, Svare CW, Turner KA. The effect of repeated firings and strength on marginal distortion in two ceramometal systems. J PROWHET
diminish the seating pressure and reduce the possibility of fracture. Rounding of all line angles is suggested to prevent the concentration of stress noted by Walton and Leven25 in photoelastic studies.
SUMMARY
AND
CONCLUSIONS
This study evaluated the marginal fit of four ceramic crown systems, (1) metal ceramic crown with a metal-butt facial margin, (2) metal ceramic crown with a porcelain facial margin, (3) Cerestore crown, and (4) Dicer crown. The results indicated that all four crown systems yielded comparable and acceptable marginal fit. The all-ceramic crowns exhibited various cracks under laboratory conditions. Suggestions were made for avoiding clinical fractures.
DENT 1981;45:502-6. 15. Shillingburg HT, Hobo
distortion 1973;29:276-64.
1. Faull TW, Hesby RA, Pelleu GB Jr, Eastwood GW. Marginal opening of single and twin platinum foil-bonded aluminous porcelain crowns. J PROSTHET DENT 1985;53:29-33. 2. Ghan C, Haraszthy G, Jurgen G, Heiner W. The marginal fit of Cerestore full ceramic crowns: a preliminary report. Quintessence Int 1985;16:399402. 3. Belser US, MacEntee MI, Richter WA. Fit of three porcelain-fusedto-metal marginal designs in viva: a scanning electron microscope study. J PRIXJTHET DENT X%$53:24-9. Van Rensburg F, Strating H. Evaluation of the marginal integrity of ceramometal restorations: part II. J PRWTHET DENT 1984;52:210-4. Crispin BJ, Watson JF, Frawley JF. Silver plated dies. part III: marginal accuracy of cast restorations. J PROS= DENT 1984;51:768-73. Kawamura RM, Swartx ML, Phiiips RW, Dykema RW, Davis WH. Marginal seal of cast full crowns: an in vitro study. Gen Dent 1983;31:292-4. Antonson DE, Fischlschweiger W. Scanning electron microscopy in clinical dental research: observation of die-spaced and non-die-spaced cast gold margins before and after cementation. Fla Dent J 1983;54:15-8. a. Pascoe DF. An evaluation of the marginal adaptation of extracoronal restorations during cementation. J PROSTH~T DENT 1983;49:657-62. 9. Faucher RR, Nicholls JI. Distortion related to margin design in porcelainfused-to-metal restorations. J PROS= DENT 1980,43:149-55.
S. I. Vitsentzos, University
to directly
design and margin J PROSTHET DENT
16. Waerhaug J. Histologic considerations which govern where the margins of restorations should be located in relation to the gingiva. Dent Clin North Am 1960,March:161-76. 17. Lo+ H. Reaction of marginal periodontal tissues to restorative procedures. Int Dent J 196&l&759-78. 18. Lugassy AA, Moffa JP, Ellison JA. Cast glass ceramic crowns: a one-year clinical study. Calif Dent Assoc J 1986;14:72-7. 19. Vyronis P. A simplified approach to the complete porcelain margin. J PROSTHET DENT 1979;42:592-3. 20. McLean JW, Von Fraunhofer JA. The estimation of cement film thickness by an in viva technique. Brit Dent J 1971;131:107-11. 21. Tjan AHL, Miller GD, Sarkissian R. Internal escape channel to improve the seating of full crowns with various marginal configurations: a followup study. J PROSTHET DENT 1985;53:759-63. 22. Tjan AHL, Sarkissian R. The effectiveness of an internal escape channel’s role in crown cementation with various dental cements. Gen Dent 1985;33:209-11. 23. Tjan AHL, Sarkissian R. Comparison of internal escape channels with die spacing and occlusal venting. J PR~~THET DENT 1985;53:613-7. 24. Tjan AHL, Sarkissian R. Internal escape channel: an alternative to venting complete crowns. J PR~~THET DENT 1984,52:50-6. 25. Walton CB, Leven MM. A preliminary report of photoelastic tests of strain patterns within jacket crowns. J Am Dent Assoc 1955;50:44-8.
REFERENCES
A new device teeth
S, Fisher DW. Preparation in porcelain-fused-to-metal restorations.
Reprint requests to: DR. MATTY P. &BATE LOMA LINDA UNIVEFWT~ SCHOOL OF DENTISTRY LOMA LINDA, CA 92350
examine
parallelism
of abutment
D.D.S., Dr. Dent.*
of Thesaaloniki,
School
of Dentistry,
Thessaloniki,
Greece
The path of insertion is essential for the successful seating of ftxed partial dentures. A new device is described that directly examines the parallelism of the axial walls of the abutment teeth. It can also be used to create guiding planes for abutment teeth of removable partial dentures and determine the path of insertion of a Maryland Bridge fixed partial denture. The various parts of this device, its principle of operation, the results of its use, and advantages in relation to similar devices are presented. (J PROSTRET DENT 1989$1:691-4.)
T
he parallelism of the axial walls of abutment teeth is fundamental for the accurate placement of a fixed partial denture (FPD). The path of insertion of an FPD is expressed
‘Assistant
Professor,
Department
THEJOURNALOFPROSTHETICDENTISTRY
of Fixed
Prosthesis.
by the anglebetweenthe horizontal plane through the teeth and the plane tangent to the axial wall of the abutment teeth. When the abutment teeth do not have a particular inclination, the path of insertion of the FPD is approximately 90 degrees. When an abutment tooth is inclined mesially, removal of an inordinate amount of tooth substance can 531
VITSENTZOS
Fig.
1. Schematic view of device.
Z Fig.
-b
2. Device arm.
threaten the integrity of the dental pulp. The path of insertion of the FPD in this case will be less than 90 degrees and depends on the inclination of the abutment tooth. When the inclination angle of the abutment tooth is less, so is the angle of the path of insertion angle, jeopardizing the parallelism with the axial wall of the other abutment tooth. In treatment planning, preemptive measures are instituted to determine the path of insertion to ensure parallel axial walls of abutment teeth. This article describes a device to program parallelism of the axial walls of the abutment teeth.
DEVICE
Fig. 532
3. Device base.
DESCRIPTION
Fig. 1 shows schematically the proposed device. Figs. 2 and 3 illustrate the two major sections of the device, the arm and base, respectively. The arm of the device (Fig. 2) consists of two sections, D and E, and joint in 2. Joint 2 provides the ability to the arm sections D and E to move relative to each other on one plane around 2. Apertures A, B, and C on section D are used to lengthen or shorten the arm, depending on the specific patient, by using one hole in placing the arm on the base of the device. If the arm of the device in Fig. 2 is positioned on the base of the device in Fig. 3 by screwing part h into one of the holes MAY
1989
VOLUME
61
NUMBED
5
NEW
DEVICE
TO DIRECTLY
EXAMINE
PARALLELISM
Fig. Fig.
4. Device parts and aluminum trays. 5. Device with a temporary aluminum
crown.
Fig. 6. A, Prepared abutment teeth. B, Device stabilization on prepared tooth and path of insertion. C, Inspecting parallelism of axial walls of abutment tooth in relation to path of insertion.
A, B, or C, then the device is complete as shown in Fig. 1. Figs. 4 and 5 illustrate the paralleling device.
PRINCIPLE
OF OPERATION
After the abutment teeth have been prepared, the parallelism of the axial walls is examined. First an appropriate tooth is selected for attaching the device. In specific patients two or even three teeth can be selected. TEE
JOURNAL
OF PROSTEETIC
DENTISTRY
The length of the device arm is then specified by selecting the proper hole among A, B, or C, so that the guide pin conveniently reaches the teeth under examination. The aluminum tray (Fig. 1, c) is filled with stent or eiastomeric impression material and the device is positioned on the tooth selected for this purpose. After the material has polymerized the device becomes stable. Nut 5 is loosened and the arm can move freely. The arm is moved so that pin g (Fig. 1)
533
VITSENTZOS
sions are made and a cast is poured. The cast is examined on a laboratory surveyor and the parallelism of the abutment teeth is verified. This technique has the following disadvantages: (1) it requires additional visits before the final impression, (2) there is no certainty that this second appointment will ensure parallelism because the exact location and amount of tooth structure for removal requires an additional impression, and (3) conservativism is diflicult. Conversely, direct methods use devices called intraoral and extraoral parallelographs. The intraoral parallelographs have the disadvantage of an additional visit for device preparation1-7 and the extraoral parallelographs have limited stability.3* s-11 The device presented can determine the parallelism directly, easily, and efficiently. This device can also be used to create the guide planes for the abutment teeth for a removable partial denture and determine the path of insertion of a Maryland fixed partial denture.
SUMMARY The parallelism of the axial walls of the abutment teeth is essential for the placement of an FPD. The programmed examination of parallelism of abutment teeth facilitates tooth preparation and encourages conservative tooth reduction. A new device is described to directly examine parallelism of abutment teeth during preparation. Fig. 7. A, Device stabilization with aluminum tray and elastomeric material and path of insertion. B, Inspecting parallelism of axial walls of abutment teeth in relation to path of insertion shown in A.
approaches and touches tangentially, with its “vertical” part, the axial wall of the selected and prepared reference tooth. In this position nut b is fastened and pin g assumes a constant direction. This is the direction of the axial wall of the tooth and also the path of insertion. By moving sections E and D of the arm, the pm can be directed from the reference tooth and positioned adjacent to the next abutment tooth. If the pin contacts the axial wall of the second tooth intimately (in alI points) the two teeth are parallel. The same procedure is followed for all teeth during preparation of the FPD (Figs. 6 and 7).
DISCUSSION
AND
CONCLUSIONS
Providing parallelism in the abutment teeth is a situation that every dentist faces during tooth preparation. This is more critical when more teeth are prepared. For inspection by the indirect method, intraoral impres-
534
REFERENCES 1. Courtade GL, Tiiermans JJ. Pins in restorative dentistry. St Louis: CV Mosby Co, 1971;183,185,244. 2. Goransson P, Parmlid A. A new parallelii instrument, Paramsx II and the Kodex drills. J PROSTHITT DENT 1975;34:31-4. 3. Green HD. Controlled tooth preparation. J PRO~TH&P DENT 1971;26:1707. 4. Jeanneret 5. 6. 7. 8.
M. L’inlay a cramppons et ses applications. Paris: Jul Prelat, 1953;21. Karlstrom G. A paralleling instrument for the guidance of pin channels and high-speed preparations. J PMSTHET DENT 1971;26:41-55. Mosteller JH. Pin castings by a paraileling device and hydrocolloid technique. Dent Clin North Am 1970;14:63-61. Schnepper HE, Baum L. Miniature parallel pins for retention of cast restorations. J PROSTHET J&NT 1961;11:772-80. Gamer S, Zusman S. Position finder for parallelism. J PROBTHET DENT
1965;15:717-8. 9. Green HD. A rational DENT 1965;15:100-5.
approach
to full crown preparation.
J PROSTHET
10. Solle W. The parallelo-facere: a parallel drillii machine for use in the cavity. J Am Dent Assoc 1961;63:343-52. 11. ‘Pybnan SD. Theory and practice of crown and bridge prosthodontics. 6th ed. St Louis: CV Mosby Co, 1970;335. Reprint
requests to:
DR. S. I. V~ENTZOS MIAOIJLI 12 GR-54642 THESSALONIKI GREECE
MAY
1SSS
VOLUME
61
NUMBER
6
10. Eden GT, Franklin OM, Powel JM, Ohta Y, Dickson G. Fit of porcelainfused-to-metal crown and bridge castings. J Dent Res 1979;58:2360-79. 11. Hunt JL, Cruikshanks-Boyd DW, Davies EH. The marginal characteristics of collarless bonded porcelain crowns produced using a separating medium technique. Quintessence Dent Technol1978;9:21. 12. DeHoff PH. Anusavice HJ, Boyce RJ. Analysis of thermally induced stresses in porcelain metal systems. J Dent Res 1983;62:593-7. 13. Bridger DV, Nicholls JI. Distortion of ceramometal fixed partial dentures during the firing cycle. J PROSTHET DENT 1961;45:507-14. 14. Buchanan WT, Svare CW, Turner KA. The effect of repeated firings and strength on marginal distortion in two ceramometal systems. J PROWHET
diminish the seating pressure and reduce the possibility of fracture. Rounding of all line angles is suggested to prevent the concentration of stress noted by Walton and Leven25 in photoelastic studies.
SUMMARY
AND
CONCLUSIONS
This study evaluated the marginal fit of four ceramic crown systems, (1) metal ceramic crown with a metal-butt facial margin, (2) metal ceramic crown with a porcelain facial margin, (3) Cerestore crown, and (4) Dicer crown. The results indicated that all four crown systems yielded comparable and acceptable marginal fit. The all-ceramic crowns exhibited various cracks under laboratory conditions. Suggestions were made for avoiding clinical fractures.
DENT 1981;45:502-6. 15. Shillingburg HT, Hobo
distortion 1973;29:276-64.
1. Faull TW, Hesby RA, Pelleu GB Jr, Eastwood GW. Marginal opening of single and twin platinum foil-bonded aluminous porcelain crowns. J PROSTHET DENT 1985;53:29-33. 2. Ghan C, Haraszthy G, Jurgen G, Heiner W. The marginal fit of Cerestore full ceramic crowns: a preliminary report. Quintessence Int 1985;16:399402. 3. Belser US, MacEntee MI, Richter WA. Fit of three porcelain-fusedto-metal marginal designs in viva: a scanning electron microscope study. J PRIXJTHET DENT X%$53:24-9. Van Rensburg F, Strating H. Evaluation of the marginal integrity of ceramometal restorations: part II. J PRWTHET DENT 1984;52:210-4. Crispin BJ, Watson JF, Frawley JF. Silver plated dies. part III: marginal accuracy of cast restorations. J PROS= DENT 1984;51:768-73. Kawamura RM, Swartx ML, Phiiips RW, Dykema RW, Davis WH. Marginal seal of cast full crowns: an in vitro study. Gen Dent 1983;31:292-4. Antonson DE, Fischlschweiger W. Scanning electron microscopy in clinical dental research: observation of die-spaced and non-die-spaced cast gold margins before and after cementation. Fla Dent J 1983;54:15-8. a. Pascoe DF. An evaluation of the marginal adaptation of extracoronal restorations during cementation. J PROSTH~T DENT 1983;49:657-62. 9. Faucher RR, Nicholls JI. Distortion related to margin design in porcelainfused-to-metal restorations. J PROS= DENT 1980,43:149-55.
S. I. Vitsentzos, University
to directly
design and margin J PROSTHET DENT
16. Waerhaug J. Histologic considerations which govern where the margins of restorations should be located in relation to the gingiva. Dent Clin North Am 1960,March:161-76. 17. Lo+ H. Reaction of marginal periodontal tissues to restorative procedures. Int Dent J 196&l&759-78. 18. Lugassy AA, Moffa JP, Ellison JA. Cast glass ceramic crowns: a one-year clinical study. Calif Dent Assoc J 1986;14:72-7. 19. Vyronis P. A simplified approach to the complete porcelain margin. J PROSTHET DENT 1979;42:592-3. 20. McLean JW, Von Fraunhofer JA. The estimation of cement film thickness by an in viva technique. Brit Dent J 1971;131:107-11. 21. Tjan AHL, Miller GD, Sarkissian R. Internal escape channel to improve the seating of full crowns with various marginal configurations: a followup study. J PROSTHET DENT 1985;53:759-63. 22. Tjan AHL, Sarkissian R. The effectiveness of an internal escape channel’s role in crown cementation with various dental cements. Gen Dent 1985;33:209-11. 23. Tjan AHL, Sarkissian R. Comparison of internal escape channels with die spacing and occlusal venting. J PR~~THET DENT 1985;53:613-7. 24. Tjan AHL, Sarkissian R. Internal escape channel: an alternative to venting complete crowns. J PR~~THET DENT 1984,52:50-6. 25. Walton CB, Leven MM. A preliminary report of photoelastic tests of strain patterns within jacket crowns. J Am Dent Assoc 1955;50:44-8.
REFERENCES
A new device teeth
S, Fisher DW. Preparation in porcelain-fused-to-metal restorations.
Reprint requests to: DR. MATTY P. &BATE LOMA LINDA UNIVEFWT~ SCHOOL OF DENTISTRY LOMA LINDA, CA 92350
examine
parallelism
of abutment
D.D.S., Dr. Dent.*
of Thesaaloniki,
School
of Dentistry,
Thessaloniki,
Greece
The path of insertion is essential for the successful seating of ftxed partial dentures. A new device is described that directly examines the parallelism of the axial walls of the abutment teeth. It can also be used to create guiding planes for abutment teeth of removable partial dentures and determine the path of insertion of a Maryland Bridge fixed partial denture. The various parts of this device, its principle of operation, the results of its use, and advantages in relation to similar devices are presented. (J PROSTRET DENT 1989$1:691-4.)
T
he parallelism of the axial walls of abutment teeth is fundamental for the accurate placement of a fixed partial denture (FPD). The path of insertion of an FPD is expressed
‘Assistant
Professor,
Department
THEJOURNALOFPROSTHETICDENTISTRY
of Fixed
Prosthesis.
by the anglebetweenthe horizontal plane through the teeth and the plane tangent to the axial wall of the abutment teeth. When the abutment teeth do not have a particular inclination, the path of insertion of the FPD is approximately 90 degrees. When an abutment tooth is inclined mesially, removal of an inordinate amount of tooth substance can 531
VITSENTZOS
Fig.
1. Schematic view of device.
Z Fig.
-b
2. Device arm.
threaten the integrity of the dental pulp. The path of insertion of the FPD in this case will be less than 90 degrees and depends on the inclination of the abutment tooth. When the inclination angle of the abutment tooth is less, so is the angle of the path of insertion angle, jeopardizing the parallelism with the axial wall of the other abutment tooth. In treatment planning, preemptive measures are instituted to determine the path of insertion to ensure parallel axial walls of abutment teeth. This article describes a device to program parallelism of the axial walls of the abutment teeth.
DEVICE
Fig. 532
3. Device base.
DESCRIPTION
Fig. 1 shows schematically the proposed device. Figs. 2 and 3 illustrate the two major sections of the device, the arm and base, respectively. The arm of the device (Fig. 2) consists of two sections, D and E, and joint in 2. Joint 2 provides the ability to the arm sections D and E to move relative to each other on one plane around 2. Apertures A, B, and C on section D are used to lengthen or shorten the arm, depending on the specific patient, by using one hole in placing the arm on the base of the device. If the arm of the device in Fig. 2 is positioned on the base of the device in Fig. 3 by screwing part h into one of the holes MAY
1989
VOLUME
61
NUMBED
5
NEW
DEVICE
TO DIRECTLY
EXAMINE
PARALLELISM
Fig. Fig.
4. Device parts and aluminum trays. 5. Device with a temporary aluminum
crown.
Fig. 6. A, Prepared abutment teeth. B, Device stabilization on prepared tooth and path of insertion. C, Inspecting parallelism of axial walls of abutment tooth in relation to path of insertion.
A, B, or C, then the device is complete as shown in Fig. 1. Figs. 4 and 5 illustrate the paralleling device.
PRINCIPLE
OF OPERATION
After the abutment teeth have been prepared, the parallelism of the axial walls is examined. First an appropriate tooth is selected for attaching the device. In specific patients two or even three teeth can be selected. TEE
JOURNAL
OF PROSTEETIC
DENTISTRY
The length of the device arm is then specified by selecting the proper hole among A, B, or C, so that the guide pin conveniently reaches the teeth under examination. The aluminum tray (Fig. 1, c) is filled with stent or eiastomeric impression material and the device is positioned on the tooth selected for this purpose. After the material has polymerized the device becomes stable. Nut 5 is loosened and the arm can move freely. The arm is moved so that pin g (Fig. 1)
533
VITSENTZOS
sions are made and a cast is poured. The cast is examined on a laboratory surveyor and the parallelism of the abutment teeth is verified. This technique has the following disadvantages: (1) it requires additional visits before the final impression, (2) there is no certainty that this second appointment will ensure parallelism because the exact location and amount of tooth structure for removal requires an additional impression, and (3) conservativism is diflicult. Conversely, direct methods use devices called intraoral and extraoral parallelographs. The intraoral parallelographs have the disadvantage of an additional visit for device preparation1-7 and the extraoral parallelographs have limited stability.3* s-11 The device presented can determine the parallelism directly, easily, and efficiently. This device can also be used to create the guide planes for the abutment teeth for a removable partial denture and determine the path of insertion of a Maryland fixed partial denture.
SUMMARY The parallelism of the axial walls of the abutment teeth is essential for the placement of an FPD. The programmed examination of parallelism of abutment teeth facilitates tooth preparation and encourages conservative tooth reduction. A new device is described to directly examine parallelism of abutment teeth during preparation. Fig. 7. A, Device stabilization with aluminum tray and elastomeric material and path of insertion. B, Inspecting parallelism of axial walls of abutment teeth in relation to path of insertion shown in A.
approaches and touches tangentially, with its “vertical” part, the axial wall of the selected and prepared reference tooth. In this position nut b is fastened and pin g assumes a constant direction. This is the direction of the axial wall of the tooth and also the path of insertion. By moving sections E and D of the arm, the pm can be directed from the reference tooth and positioned adjacent to the next abutment tooth. If the pin contacts the axial wall of the second tooth intimately (in alI points) the two teeth are parallel. The same procedure is followed for all teeth during preparation of the FPD (Figs. 6 and 7).
DISCUSSION
AND
CONCLUSIONS
Providing parallelism in the abutment teeth is a situation that every dentist faces during tooth preparation. This is more critical when more teeth are prepared. For inspection by the indirect method, intraoral impres-
534
REFERENCES 1. Courtade GL, Tiiermans JJ. Pins in restorative dentistry. St Louis: CV Mosby Co, 1971;183,185,244. 2. Goransson P, Parmlid A. A new parallelii instrument, Paramsx II and the Kodex drills. J PROSTHITT DENT 1975;34:31-4. 3. Green HD. Controlled tooth preparation. J PRO~TH&P DENT 1971;26:1707. 4. Jeanneret 5. 6. 7. 8.
M. L’inlay a cramppons et ses applications. Paris: Jul Prelat, 1953;21. Karlstrom G. A paralleling instrument for the guidance of pin channels and high-speed preparations. J PMSTHET DENT 1971;26:41-55. Mosteller JH. Pin castings by a paraileling device and hydrocolloid technique. Dent Clin North Am 1970;14:63-61. Schnepper HE, Baum L. Miniature parallel pins for retention of cast restorations. J PROSTHET J&NT 1961;11:772-80. Gamer S, Zusman S. Position finder for parallelism. J PROBTHET DENT
1965;15:717-8. 9. Green HD. A rational DENT 1965;15:100-5.
approach
to full crown preparation.
J PROSTHET
10. Solle W. The parallelo-facere: a parallel drillii machine for use in the cavity. J Am Dent Assoc 1961;63:343-52. 11. ‘Pybnan SD. Theory and practice of crown and bridge prosthodontics. 6th ed. St Louis: CV Mosby Co, 1970;335. Reprint
requests to:
DR. S. I. V~ENTZOS MIAOIJLI 12 GR-54642 THESSALONIKI GREECE
MAY
1SSS
VOLUME
61
NUMBER
6