SECTION
EDITOR
tive considerations fferent root form
for a fixed implant implant systems
prost
Robert J. Cronin, Jr., DDS, MSa Wilford
Hall U.S. Air Force Medical
Center, San Antonio,
Texas
A precise fit at the prosthesis attachment interface is necessary to assure atraumatic loading of the implant fixture. The required high degree of frame accuracy can be more difficult to achieve when a single fixed prosthesis uses different root form implant systems for support. Two clinical protocols are described for these fixed implant prostheses. The first protocol uses a semiprecision attachment for the restorations. The second protocol uses a modified abutment system and a one-piece frame design.(J PROSTHETDENT 1992;67:124-9.)
T
.
he prmciple of osseointegration has revolutionized prosthodontic options for the replacement of missing teeth and related oral structures.l Much research has been accomplished detailing the biologic response of hard tissues to titanium implants2 and the long-term clinical ability of osseointegrated implants to withstand considerable masticatory loading.3 Additional research activity has investigated the biomaterial and biomechanical considerations in implant design and attachment.4-7 The views expressed herein are those of the author and do not necessarily reflect the views of the United States Air Force or the Department of Defense. Presented at the Sixty-first Annual Scientific meeting of the American Academy of Restorative Dentistry, Chicago, Ill. %olonel, U.S. Air Force, DC; Chairman, Department of Prosth-
odontics. 10/l/32999
Fig. 1. Panoramic radiograph image of an Integral implant in mandibular first molar region and a Branemark implant in second molar region.
124
The prosthodontic aspects of dental implant treatment are not well represented in dental literature. Although many studies have examined the effect,of occlusal forces on implant support and the selection of occlusal restorative materials,8‘11 little work has focused on the prosthesis-implant interface. Achieving optimal function is dependent on the precise technology required to maintain the fixed prosthodontic restoration through a passive fit of the superstructure on the implant abutments.r2 The term “precise passive prosthesis” has been suggested to describe the fit required for prosthesis stability and atraumatic loading of the implant fixture.r3 If a passive fit of implant abutment to prosthesis is not achieved, the subsequent stress can result in increased levels of perifixtural bone resorption or failure of the prosthodontic implant components.14-16 Numerous references have been made to the difficulty of achieving an absolutely accurate fit by casting dental alloys to machined gold cylinders. 17-lgSeveral authors have suggested corrective measures when a framework does not
Fig.
2. Transfer impression copings in place.
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1992
VOLUME
67
NUMBER
1
RESTORATIVE
CONSIDERATIONS
Fig. 3. SEM image of articular surfaces. A, Branemark gold cylinder (original magnification x200). B, Integral waxing sleeve (original magnification x200). C, B&remark gold cylinder (original magnification X1000). D, Cast Integral waxing sleeve (original magnification x1000). E, Cast Integral waxing sleeve following trial fitting procedures. Note burnishing of grain structure (original magnification x1000).
passively fit the abutment cylinders. These measures normally involve soldering techniques,17, 2o but cementing techniquesls and a casting modification technique involving an acrylic resin pickup impression of specific gold cylinders have also been suggested.ig Other implant restor-
THE
JOURNAL
OF PROSTHETIC
DENTISTRY
ative systems using plastic burnout patterns have resulted in similar casting difficulties. A custom milling device with diamond paste is recommended to refine the attachment interface when using burnout patterns to achieve a passive prosthesis fit.21
125
CRONIN
Fig. 4. Final restorations with semiprecision mortice rest attachment. Fig. 5. Final occlusal adjustment using occlusal registration strips. (Artus Corporation, Engelwood, N.J.) Fig. 6. Occlusal view of screw-retained fixed implant prosthesis with semiprecision connector.
Fig. 7. Radiograph of final restoration utilizing Integral and Branemark prostbodontic components.
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1992
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CONSfDERATIONS
Fig. 8. Anterior modification abutment in place demonstrating similarity of abutment components. Fig. 9. Intraoral view of verification index in place. Fig. 10. Occlusal view of screw-retained one-piece implant prosthesis. Fig. 11. Lingual view. Note similarity of abutment contours.
IMPLANT
SYSTEMS
Most clinicians will simplify the restorative attachment of implant restorations by using a single implant system to support the prosthesis. The use of two different implant systems within Lhe same restorative segment is infrequently seen.“’ A further complication in the use of two different implant systems in a restorative segment occurs when one system uses plastic burnout patterns while the other uses machined gold cylinders for the prosthesis attachment. The conventional implant treatment of a patient with a Kennedy Class II partially edentulous mandible was complicated by the predominance of medullary bone of low trabecular density (type IV). Type IV bone is associated with an increase in the incidence of implant fixture failure.23 This poor bone quality dictated the surgical placement of an Integral HA coated implant (Calcitec, Inc., Carlsbad, Calif.) at the anterior site following the placement of a Branemark fixture (Nobelpharma USA, Inc.,
THE
JOURNAL
OF PROSTHETIC
DENTISTRY
Chicago, Ill.) at the predetermined distal site in the residual ridge (Fig. 1). The restorative complications created by using these particular systems are of interest, as the Integral system uses a plastic burnout pattern while the Brinemark system uses a premachined metallic gold cylinder as the means of restorative attachment. Following successful osseointegration and abutment connection surgery, system-specific impression transfer copings were used (Fig. 2). Dissimilar transfer techniques required a combination closed/open custom impression tray. Prior to prosthesis fabrication, a scanning electron microscope (SEM) study was accomplished to more closely observe the cast versus machined prosthesis surface at the implant-attachment interface. This study revealed the anticipated variation of metallic grain surfaces in the cast attachment versus Lhe predictable machined surface (Fig. 3, A to D). Of particular interest was the noticeable burnishing of the metallic grain surface in the cast attachment following trial fitting procedures with disclosing wax (Fig. 3,
127
CRQNIN
Fig. 12. Radiograph demonstrating similarity of attachment mechanism with modification abutment in place on anterior Integral implant. E). This variance in metallic cylinder fit precipitated a decision to fabricate the prosthesis with a semiprecision attachment (Mortice Rest, J.M. Ney Co., Bloomfield, Conn.) to assure an optimally passive prosthesis fit. The two mandibular implant-supported single units were cast separately with tbe receptor attachment in the anterior unit and the insert attachment in the posterior unit. This allowed for the anticipated slight variance in prosthesis-to-implant fit (Fig. 4). As always, careful attention was paid to precise occlusal adjustment, maintaining an optimally stable occlusion in centric relation and anterior disclusion in all eccentric movements (Fig. 5). The two units are screwretained and radiographically present an intaglio contour that is conveniently hygienic (Figs. 6 and 7).
ABUTMENT
MODIFICATION
Although the restoration of different abutments through the use of semiprecision attachments was clinically acceptable, an alternative method using abutment modification was subsequently accomplished. The use of an abutment system that is machined to screw into one implant system fixture and convert that system to the prosthodontic structure of a different system allows for a more precise final restoration that uses machined gold cylinders. A modification abutment (Implant Innovations, Inc., West Palm Beach, Fla.) was placed on the anterior Integral fixture, converting that fixture to a replica of a B&remark abutment cylinder. With this approach, the restoration can proceed as if on two similar implant fixtures, presenting intraorally with the same abutment configuration (Fig. 8). This similar abutment configuration simplifies the impression coping technique and facilitates verification of master cast accuracy by use of an intraoral index (Fig. 9).24 The restoration can be waxed to the machined gold cylinders and cast as a single unit with assurance of the same accu128
racy afforded when similar implant attachments are used. If the practitioner gives careful attention to occlusal adjustment, a clinically acceptable restoration with an excellent prognosis can be achieved (Figs. 1Gthrough 12).
SUMMARY The fabrication of a fixed partial denture using different implant systems has been presented. Clinical observation, supported by scanning electron microscopy, reveals slight variations in the fit of the prosthesis attachment of the different implant systems. Two clinical protocols are suggested in this situation. The first uses a semiprecision attachment to join the restorations of the different implant systems. The second uses a modification abutment system to create conformity of the prosthodontic attachments. Both techniques produce clinically acceptable implant restorations to achieve optimal, functional, and esthetic treatment objectives. REFERENCES 1. Br&mnark P-I. Osseointegration and its experimental background. J PROSTHET DENT 1983;50:399-410.
2. Albrektsson T, Brinemark PI, Hansson HA, Lindstrom J. Osseointegrated titanium implants. Requirements for ensuring a long-lasting direct bone-to-implant anchorage in man. Acta Orthop Stand 1981;52:15670.
3. Adell R, Lekholm U, Rockier B, Brinemark PI. A 15-year study of osseointegrated implants in the treatment of the edentulous jaw. Int J Oral Surg 1981;6:387-416. 4. Skalak R. Biomechanical considerations in osseointegrated prostheses. J PROSTHET DENT 1983;49:843-8. 5. Brunski JB. Biomaterials and biomecbanics in dental implant design. Int J Oral Maxillofac Implants 1988;3:85-97. 6. van Rossen IP, Braak LH, de Putter C, de Groat K. Stress-absorbing elements in dental implants. J PROWHET DENT 1990;64:198-205. 7. Gross UM. Biocompatibility-the interaction of biomaterials and host response. J Dent Educ 1988;52:798-803. 8. Falk H, Laurel1 L, Lundgren D. Occlusal force patterns in dentitions with mandibular implant-supported fixed cantilever prostheses oc-
JANUARY
1092
VOLUME
67
NUMBER
1
RESTORATIVE
CONSIDERATIONS
cludedwithcompletedentures.IntJOralMaxillofacImplants1989;4:5562.
9. Lundgren D, Falk H, Laurel1 L. The influence of number and distribution of occlusal cantiliver contacts on closing and chewing forces in dentitions with implant-supported fixed prostheses occluding with complete dentures. Int J Oral Maxillofac Implants 1989;4:2’77-83. 10. Davis DM, Rimrott R, Zarb GA. Studies on frameworks for osseointegrated prostheses. Part 2. The effect of adding acrylic resin or porcelain to form the occlusal superstructure. Int J Oral Maxillofac Implants 1988;3:275-80. 11. Chapman RJ. Principles of occlusion for implant prostheses: guidelines for position, timing, and force of occlusal contacts. Quintessence Int 1989;20:473-80. 12. Branemark P-I. (Forward) In: Hobo S, Ichida E, Garcia LT. Osseointegration and occlusal rehabilitation. Chicago: Quintessence Publishing Co, 1989. 13. Langer B, Sullivan DY. Osseointegration: its impact on the interrelationship of periodontics and restorative dentistry. Part II. Int J Periodont Res Dent 1989;9:165-83. 14. Worthington P, Bolender CL, Taylor TD. The Swedish system of osseointegrated implants: problems and complications encountered during a 4-year trial period. Int J Oral Maxillofac Implants 1987;2:7784.
15. Balshi TJ. Preventing and resolving complications with osseointegrated implants. Dent Clin North Am 1989;33:821-68. 16. Branemark PI. Tooth replacement by oral endoprostheses: clinical aspects. d Dent Educ 1988;52:821-3.
THE
JOURNAL
OF PROSTHETIC
DENTISTRY
17. Sutherland JK, Hallam RF. Soldering technique for osseointegrated implant prostheses. J PROSTHET DENT 1990;63:242-4. 18. Sellers GC. Direct assembly framework for osseointegrated implant prosthesis. J PROSTHET DENT 1989;62:662-8. 19. Pare1 SM. Modified casting technique for osseointegrated fixed prosthesis fabrication: a preliminary report. Int J Oral Maxillofac Implants 1989;4:33-40. 20. Hobo S, Ichida E, Garcia LT. Osseointegration and occlusal rehabilitation. Chicago: Quintessence Publishing Co, 1989:176, 21. Lewis S, Avera A, Engleman M, Beumer J III. The restoration of improperly inclined osseointegrated implants. Xnt J Oral Maxillofac Implants 1989;4:147-52. 22. Lecocq KR, Koehler GK, Black WB. The use of two implant systems within the same restorative segment: a clinical report. Int J Oral Maxillofac Implants 1990;&289-91. 23. JafKn RA, Berman CL. The excessive loss of Branemark fixtures in type IV bone: a 5-year analysis. J Periodontol 1991;62:2-4. 24. Knudson RC, Williams EO, Kemple KP. Implant transfer coping verification jig. J PROSTHET DENT 1989;61:601-2. Reprint requests to: COLONEL ROBERT J. CRONIN, JR., USAF, DC CHAIRMAN, DEPARTMENT OF PROSTHODONTICS WILFORD HALL USAF MEDICAL CENTER/SGDP LACKLAND AFB, TX 78236-5300
129
EDITOR
tive considerations fferent root form
for a fixed implant implant systems
prost
Robert J. Cronin, Jr., DDS, MSa Wilford
Hall U.S. Air Force Medical
Center, San Antonio,
Texas
A precise fit at the prosthesis attachment interface is necessary to assure atraumatic loading of the implant fixture. The required high degree of frame accuracy can be more difficult to achieve when a single fixed prosthesis uses different root form implant systems for support. Two clinical protocols are described for these fixed implant prostheses. The first protocol uses a semiprecision attachment for the restorations. The second protocol uses a modified abutment system and a one-piece frame design.(J PROSTHETDENT 1992;67:124-9.)
T
.
he prmciple of osseointegration has revolutionized prosthodontic options for the replacement of missing teeth and related oral structures.l Much research has been accomplished detailing the biologic response of hard tissues to titanium implants2 and the long-term clinical ability of osseointegrated implants to withstand considerable masticatory loading.3 Additional research activity has investigated the biomaterial and biomechanical considerations in implant design and attachment.4-7 The views expressed herein are those of the author and do not necessarily reflect the views of the United States Air Force or the Department of Defense. Presented at the Sixty-first Annual Scientific meeting of the American Academy of Restorative Dentistry, Chicago, Ill. %olonel, U.S. Air Force, DC; Chairman, Department of Prosth-
odontics. 10/l/32999
Fig. 1. Panoramic radiograph image of an Integral implant in mandibular first molar region and a Branemark implant in second molar region.
124
The prosthodontic aspects of dental implant treatment are not well represented in dental literature. Although many studies have examined the effect,of occlusal forces on implant support and the selection of occlusal restorative materials,8‘11 little work has focused on the prosthesis-implant interface. Achieving optimal function is dependent on the precise technology required to maintain the fixed prosthodontic restoration through a passive fit of the superstructure on the implant abutments.r2 The term “precise passive prosthesis” has been suggested to describe the fit required for prosthesis stability and atraumatic loading of the implant fixture.r3 If a passive fit of implant abutment to prosthesis is not achieved, the subsequent stress can result in increased levels of perifixtural bone resorption or failure of the prosthodontic implant components.14-16 Numerous references have been made to the difficulty of achieving an absolutely accurate fit by casting dental alloys to machined gold cylinders. 17-lgSeveral authors have suggested corrective measures when a framework does not
Fig.
2. Transfer impression copings in place.
JANUARY
1992
VOLUME
67
NUMBER
1
RESTORATIVE
CONSIDERATIONS
Fig. 3. SEM image of articular surfaces. A, Branemark gold cylinder (original magnification x200). B, Integral waxing sleeve (original magnification x200). C, B&remark gold cylinder (original magnification X1000). D, Cast Integral waxing sleeve (original magnification x1000). E, Cast Integral waxing sleeve following trial fitting procedures. Note burnishing of grain structure (original magnification x1000).
passively fit the abutment cylinders. These measures normally involve soldering techniques,17, 2o but cementing techniquesls and a casting modification technique involving an acrylic resin pickup impression of specific gold cylinders have also been suggested.ig Other implant restor-
THE
JOURNAL
OF PROSTHETIC
DENTISTRY
ative systems using plastic burnout patterns have resulted in similar casting difficulties. A custom milling device with diamond paste is recommended to refine the attachment interface when using burnout patterns to achieve a passive prosthesis fit.21
125
CRONIN
Fig. 4. Final restorations with semiprecision mortice rest attachment. Fig. 5. Final occlusal adjustment using occlusal registration strips. (Artus Corporation, Engelwood, N.J.) Fig. 6. Occlusal view of screw-retained fixed implant prosthesis with semiprecision connector.
Fig. 7. Radiograph of final restoration utilizing Integral and Branemark prostbodontic components.
JANUARY
1992
VOLUME
67
NUMBER
1
RESTORATIVE
CONSfDERATIONS
Fig. 8. Anterior modification abutment in place demonstrating similarity of abutment components. Fig. 9. Intraoral view of verification index in place. Fig. 10. Occlusal view of screw-retained one-piece implant prosthesis. Fig. 11. Lingual view. Note similarity of abutment contours.
IMPLANT
SYSTEMS
Most clinicians will simplify the restorative attachment of implant restorations by using a single implant system to support the prosthesis. The use of two different implant systems within Lhe same restorative segment is infrequently seen.“’ A further complication in the use of two different implant systems in a restorative segment occurs when one system uses plastic burnout patterns while the other uses machined gold cylinders for the prosthesis attachment. The conventional implant treatment of a patient with a Kennedy Class II partially edentulous mandible was complicated by the predominance of medullary bone of low trabecular density (type IV). Type IV bone is associated with an increase in the incidence of implant fixture failure.23 This poor bone quality dictated the surgical placement of an Integral HA coated implant (Calcitec, Inc., Carlsbad, Calif.) at the anterior site following the placement of a Branemark fixture (Nobelpharma USA, Inc.,
THE
JOURNAL
OF PROSTHETIC
DENTISTRY
Chicago, Ill.) at the predetermined distal site in the residual ridge (Fig. 1). The restorative complications created by using these particular systems are of interest, as the Integral system uses a plastic burnout pattern while the Brinemark system uses a premachined metallic gold cylinder as the means of restorative attachment. Following successful osseointegration and abutment connection surgery, system-specific impression transfer copings were used (Fig. 2). Dissimilar transfer techniques required a combination closed/open custom impression tray. Prior to prosthesis fabrication, a scanning electron microscope (SEM) study was accomplished to more closely observe the cast versus machined prosthesis surface at the implant-attachment interface. This study revealed the anticipated variation of metallic grain surfaces in the cast attachment versus Lhe predictable machined surface (Fig. 3, A to D). Of particular interest was the noticeable burnishing of the metallic grain surface in the cast attachment following trial fitting procedures with disclosing wax (Fig. 3,
127
CRQNIN
Fig. 12. Radiograph demonstrating similarity of attachment mechanism with modification abutment in place on anterior Integral implant. E). This variance in metallic cylinder fit precipitated a decision to fabricate the prosthesis with a semiprecision attachment (Mortice Rest, J.M. Ney Co., Bloomfield, Conn.) to assure an optimally passive prosthesis fit. The two mandibular implant-supported single units were cast separately with tbe receptor attachment in the anterior unit and the insert attachment in the posterior unit. This allowed for the anticipated slight variance in prosthesis-to-implant fit (Fig. 4). As always, careful attention was paid to precise occlusal adjustment, maintaining an optimally stable occlusion in centric relation and anterior disclusion in all eccentric movements (Fig. 5). The two units are screwretained and radiographically present an intaglio contour that is conveniently hygienic (Figs. 6 and 7).
ABUTMENT
MODIFICATION
Although the restoration of different abutments through the use of semiprecision attachments was clinically acceptable, an alternative method using abutment modification was subsequently accomplished. The use of an abutment system that is machined to screw into one implant system fixture and convert that system to the prosthodontic structure of a different system allows for a more precise final restoration that uses machined gold cylinders. A modification abutment (Implant Innovations, Inc., West Palm Beach, Fla.) was placed on the anterior Integral fixture, converting that fixture to a replica of a B&remark abutment cylinder. With this approach, the restoration can proceed as if on two similar implant fixtures, presenting intraorally with the same abutment configuration (Fig. 8). This similar abutment configuration simplifies the impression coping technique and facilitates verification of master cast accuracy by use of an intraoral index (Fig. 9).24 The restoration can be waxed to the machined gold cylinders and cast as a single unit with assurance of the same accu128
racy afforded when similar implant attachments are used. If the practitioner gives careful attention to occlusal adjustment, a clinically acceptable restoration with an excellent prognosis can be achieved (Figs. 1Gthrough 12).
SUMMARY The fabrication of a fixed partial denture using different implant systems has been presented. Clinical observation, supported by scanning electron microscopy, reveals slight variations in the fit of the prosthesis attachment of the different implant systems. Two clinical protocols are suggested in this situation. The first uses a semiprecision attachment to join the restorations of the different implant systems. The second uses a modification abutment system to create conformity of the prosthodontic attachments. Both techniques produce clinically acceptable implant restorations to achieve optimal, functional, and esthetic treatment objectives. REFERENCES 1. Br&mnark P-I. Osseointegration and its experimental background. J PROSTHET DENT 1983;50:399-410.
2. Albrektsson T, Brinemark PI, Hansson HA, Lindstrom J. Osseointegrated titanium implants. Requirements for ensuring a long-lasting direct bone-to-implant anchorage in man. Acta Orthop Stand 1981;52:15670.
3. Adell R, Lekholm U, Rockier B, Brinemark PI. A 15-year study of osseointegrated implants in the treatment of the edentulous jaw. Int J Oral Surg 1981;6:387-416. 4. Skalak R. Biomechanical considerations in osseointegrated prostheses. J PROSTHET DENT 1983;49:843-8. 5. Brunski JB. Biomaterials and biomecbanics in dental implant design. Int J Oral Maxillofac Implants 1988;3:85-97. 6. van Rossen IP, Braak LH, de Putter C, de Groat K. Stress-absorbing elements in dental implants. J PROWHET DENT 1990;64:198-205. 7. Gross UM. Biocompatibility-the interaction of biomaterials and host response. J Dent Educ 1988;52:798-803. 8. Falk H, Laurel1 L, Lundgren D. Occlusal force patterns in dentitions with mandibular implant-supported fixed cantilever prostheses oc-
JANUARY
1092
VOLUME
67
NUMBER
1
RESTORATIVE
CONSIDERATIONS
cludedwithcompletedentures.IntJOralMaxillofacImplants1989;4:5562.
9. Lundgren D, Falk H, Laurel1 L. The influence of number and distribution of occlusal cantiliver contacts on closing and chewing forces in dentitions with implant-supported fixed prostheses occluding with complete dentures. Int J Oral Maxillofac Implants 1989;4:2’77-83. 10. Davis DM, Rimrott R, Zarb GA. Studies on frameworks for osseointegrated prostheses. Part 2. The effect of adding acrylic resin or porcelain to form the occlusal superstructure. Int J Oral Maxillofac Implants 1988;3:275-80. 11. Chapman RJ. Principles of occlusion for implant prostheses: guidelines for position, timing, and force of occlusal contacts. Quintessence Int 1989;20:473-80. 12. Branemark P-I. (Forward) In: Hobo S, Ichida E, Garcia LT. Osseointegration and occlusal rehabilitation. Chicago: Quintessence Publishing Co, 1989. 13. Langer B, Sullivan DY. Osseointegration: its impact on the interrelationship of periodontics and restorative dentistry. Part II. Int J Periodont Res Dent 1989;9:165-83. 14. Worthington P, Bolender CL, Taylor TD. The Swedish system of osseointegrated implants: problems and complications encountered during a 4-year trial period. Int J Oral Maxillofac Implants 1987;2:7784.
15. Balshi TJ. Preventing and resolving complications with osseointegrated implants. Dent Clin North Am 1989;33:821-68. 16. Branemark PI. Tooth replacement by oral endoprostheses: clinical aspects. d Dent Educ 1988;52:821-3.
THE
JOURNAL
OF PROSTHETIC
DENTISTRY
17. Sutherland JK, Hallam RF. Soldering technique for osseointegrated implant prostheses. J PROSTHET DENT 1990;63:242-4. 18. Sellers GC. Direct assembly framework for osseointegrated implant prosthesis. J PROSTHET DENT 1989;62:662-8. 19. Pare1 SM. Modified casting technique for osseointegrated fixed prosthesis fabrication: a preliminary report. Int J Oral Maxillofac Implants 1989;4:33-40. 20. Hobo S, Ichida E, Garcia LT. Osseointegration and occlusal rehabilitation. Chicago: Quintessence Publishing Co, 1989:176, 21. Lewis S, Avera A, Engleman M, Beumer J III. The restoration of improperly inclined osseointegrated implants. Xnt J Oral Maxillofac Implants 1989;4:147-52. 22. Lecocq KR, Koehler GK, Black WB. The use of two implant systems within the same restorative segment: a clinical report. Int J Oral Maxillofac Implants 1990;&289-91. 23. JafKn RA, Berman CL. The excessive loss of Branemark fixtures in type IV bone: a 5-year analysis. J Periodontol 1991;62:2-4. 24. Knudson RC, Williams EO, Kemple KP. Implant transfer coping verification jig. J PROSTHET DENT 1989;61:601-2. Reprint requests to: COLONEL ROBERT J. CRONIN, JR., USAF, DC CHAIRMAN, DEPARTMENT OF PROSTHODONTICS WILFORD HALL USAF MEDICAL CENTER/SGDP LACKLAND AFB, TX 78236-5300
129
