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Complete arch implant impression technique
Complete arch implant impression technique Junping Ma, DMDa and Jeffrey E. Rubenstein, DMD, MSb School of Dentistry, University of Washington, Seattle, Wash When making a definitive impression for an arch containing multiple implants, there are many reported techniques for splinting impression copings. This article introduces a splint technique that uses the shim method, which has been demonstrated to reduce laboratory and patient chair time, the number of impression copings and laboratory analogs needed, and the ultimate cost. (J Prosthet Dent 2012;107:405-410) To create an accurate definitive cast, it is critically important to obtain an intraoral impression that accurately captures the 3-dimensional (3-D) spatial orientation of a patient’s implants. Factors affecting the accuracy of such impressions include: splinting or not splinting impression copings; implant angulation; the number of implants; polymerization shrinkage of the impression material; the setting expansion of stone; and the design and rigidity of the impression tray. Splinting or not splinting the impression copings is among the most significant. Studies evaluating the relationship between splinting and implant impression accuracy have yielded conflicting results. Some authors have advocated the use of splinting,1-5 while others have concluded that splinting does not produce superior results.6,7According to Lee et al,8 in edentulous situations involving 4 or more implants, most in vitro studies advocated splinted impression techniques. A majority of studies published after 2003 advocate the use of splinting to improve impression fidelity. Brånemark et al9 originally described the splint technique and emphasized the importance of splinting transfer copings intraorally with acrylic resin over the floss scaffold before making an impression. The acrylic resin splinting effectively resists trans-
lation and rotation of the transfer copings within an impression when the impression is detached from the implants followed by placement of the implant analogs. Spector et al10 discussed potential problems associated with the splint technique, such as distortion of the splint materials and fracture of the connection between the splint material and the impression copings. Mojon et al11 determined that the polymerization shrinkage of acrylic resin (DuraLay; Reliance Dental Mfg Co, Worth, Ill) at 24 hours was 7% to 9%, and most shrinkage (80%) occurred within 17 minutes when materials were mixed at room temperature. The accuracy of the splinting technique described by Brånemark was questioned. Since then, many attempts have
1 Mandibular edentulous arch with 6 implants.
Resident, Graduate Prosthodontics, Department of Restorative Dentistry. Professor, Department of Restorative Dentistry, Division of Prosthodontics.
a
b
Ma and Rubenstein
been made to overcome the distortion generated by acrylic resin polymerization shrinkage. Ivanhoe et al12 proposed a now widely accepted block splinting technique, in which acrylic resin blocks are fabricated on a preliminary cast and connected intraorally before the definitive impression is made. Vigolo et al2 described the protocol of the block splinting impression technique in more detail. In their approach, the acrylic resin blocks should be prepared 1 day in advance, and the final connection should be made just before the impression procedure. In this way, the influence of polymerization shrinkage is minimized. Building on the existing body of research into splinting technique, an alternative splinting technique has
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been developed and successfully demonstrated. This alternative technique provides the advantages of the conventional splinting technique and reduces both laboratory and clinic time. Moreover, the alternative technique uses only 1 set of implant impression copings and analogs as opposed to the 2 sets needed for the conventional block splinting technique. This article
introduces a splint technique that uses the shim method, which has been demonstrated to reduce laboratory time and patient chair time, the number of impression copings and laboratory analogs needed, and the ultimate cost. In the scenario presented an implant-supported prosthesis for the edentulous mandibular arch opposed by a maxillary complete denture was
fabricated (Fig. 1). Four implants placed between the mental foramina (3.75 × 10 mm RP; Replace Nobel Biocare USA, Yorba Linda, Calif ) retained the fixed implant prosthesis, and 2 implants (4.0 × 10 mm WP; Replace Nobel Biocare USA) positioned in the first molar areas served as distal stops. The splinting method to make a definitive impression is described.
A
B
C
D
E
F
2 A, Preliminary irreversible hydrocolloid impression of 6 implant impression copings. B, Inject thin mix of acrylic resin inside impression coping sites. C, Preliminary cast. D, Loosely cover impression copings with vinyl tubing. E, Wrap vinyl tubing with light polymerizing acrylic resin material and light polymerize. F, Shim fits around impression copings passively.
The Journal of Prosthetic Dentistry
Ma and Rubenstein
407
June 2012 TECHNIQUE 1. Remove the healing abutments, irrigate the internal connection/ threads of each implant, and secure 6 open tray impression copings (Nobel Biocare, USA) to the implants to a preload of 15 Ncm with a torque wrench (Nobel Biocare, USA). Make a pre-
liminary impression with irreversible hydrocolloid material (Jeltrate; Dentsply Caulk, Milford, Del) with a metal impression tray (Rim-Lock Impression Tray; Dentsply Caulk (Fig. 2A). 2. After recovering the preliminary impression, remove the impression copings and place the healing abutments back on each implant. Store the
impression copings in the order they were placed at each implant site for the definitive impression procedure. 3. Load a disposable syringe (Monoject 412 Syringe; Salvin Dental, Charlotte, NC) with a thin mix of autopolymerizing acrylic resin (1 part polymer: 2 parts monomer) (Pattern Resin; GC Corp, Tokyo, Ja-
A
B
3 A, Facial view of open-top custom tray. B, Occlusal view of open-top custom tray. Shim, custom tray and impression copings fit passively.
A
B 4 A, Acrylic resin placed around neck of impression copings. B, Complete seating of impression copings verified with radiograph (Right side) C, (Left side)
Ma and Rubenstein
C
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pan) and inject the material into the impression coping sites inside the preliminary impression (Fig. 2B). Once the acrylic resin replication of the impression copings has polymerized, pour the rest of the impression with die stone (Vel-Mix; Kerr Corp, Orange, Calif ) with a ratio of 22 mL of water to 110 g of stone mixed under vacuum for 30 seconds. 4. Recover the preliminary cast after the stone has set for 1 hour (Fig. 2C). 5. Cut pieces of vinyl tubing (TAP Plastics, Inc, Oakland, Calif ) with an internal diameter of 6 mm and an external diameter of 8 mm so that they fit with minimal gap space around each acrylic resin impression coping replication on the preliminary cast (Fig. 2D). 6. Wrap a light polymerizing acrylic resin tray material (Triad TruTray; Densply Trubyte, York, Penn) around the vinyl tubing. Light polymerize according to the manufacturer’s in-
structions (Fig. 2E). Remove the vinyl tubing and the light polymerizing resin shim from the preliminary cast and trim the shim to fit around the impression copings passively (Fig. 2F). 7. Place 1 layer of baseplate wax (Henry Schein Dental, Melville, NY) over the impression copings and the shim for uniform relief and then adapt 1 layer of aluminum foil before fabricating an open-top impression tray with the light polymerizing acrylic resin custom tray material. Ensure access to all of the acrylic resin implant copings is possible through the opening in the top of the tray. Reinforce the tray around the open-top area with another layer of the light polymerizing acrylic resin custom tray material to increase its rigidity. Once the optimal rigidity of the tray is achieved, trim the tray 1-2 mm short of the border extensions outlined on the preliminary cast (Fig. 3A). 8. Cut a sheet of rubber dam to
follow the arch form and punch holes in the rubber dam corresponding to each impression coping. Confirm the passive fit of the open-top custom tray and the shim around the plastic impression copings on the preliminary cast (Fig. 3B). 9. Before the definitive impression appointment, place a layer of acrylic resin (Pattern Resin; GC Corp) around the neck of the impression copings. Remove the healing abutments and secure the modified impression copings on each implant and preload to 15 Ncm with the torque driver. (Fig. 4A) Verify the complete seating of each impression coping with periapical radiographs. (Fig. 4B, 4C) 10. Place the rubber dam and shim around the impression copings (Fig. 5A). Apply auto polymerizing acrylic resin around the impression copings by using a powder/liquid brush application technique with a camel hair brush (No. 000; Kolinski Rembrandt,
A
B
C
D
5 A, Place rubber dam and shim around impression copings. B, Lute shim and impression copings with acrylic resin. C, All impression copings luted to shim. D, Reinforce shim splinting framework after initial acrylic resin has polymerized.
The Journal of Prosthetic Dentistry
Ma and Rubenstein
409
June 2012 Apeldoorn, Netherlands) (Fig. 5B). Start the luting sequence from the central implant. Once the shim is polymerized to this site proceed to every other one until all the impression copings are attached to the light polymerizing resin shim with the acrylic resin (Fig. 5C). Reinforce the connection with the same auto polymerizing acrylic resin after each impression
coping site has completed the initial polymerization (Fig. 5D). Remove the rubber dam using a sharp scissor. 11. Evaluate the custom tray for border extension and border mold as in the conventional complete denture impression procedure13(Fig. 6A). Adapt 1 layer of baseplate wax on the open top of the tray. Confirm the accessibility of all the impression
copings’ guide pins by imprinting them into the underside of the wax cap. Then remove the tray, clean, dry, and coat adhesive (Impregum; ESPE, Seefeld, Germany) on the internal surface of the tray and over the compound on the borders. 12. Dispense medium viscosity impression material (Impregum; ESPE) into both an impression syringe and
A
B
6 A, Seal open-top tray with 1 layer of baseplate wax. Imprint each guide pin on wax lid. B, Seat impression tray such that all guide pins contact underside of wax lid.
A
B
C
D
7 A, Intaglio surface of impression. B, Torque each implant replica onto impression copings to 15 Ncm while using hemostat to countertorque. C, Place silicone soft tissue moulage around each implant replica. D, Definitive cast.
Ma and Rubenstein
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Volume 107 Issue 6 the custom tray. Inject the impression material around the splinted impression copings/shim and seat the impression tray such that all the guide pins contact the underside of the wax lid (Fig. 6B). Remove the wax lid after the impression material has polymerized, unscrew the guide pins, making sure they no longer engage the internal threads of each implant, and then recover the impression tray from the mouth (Fig. 7A). Replace the healing abutments on each implant. 13. Torque each implant replica onto the impression coping to 15 Ncm while using a hemostat engaging the base of the replica to provide countertorque (Fig. 7B). Place silicone soft tissue moulage (Softissue Moulage; Kerr Dental Laboratory, Orange, Calif ) around the implant replicas (Fig. 7C). Box the definitive impression with a 50:50 mixture of plaster and pumice. Pour with die stone (Die Keen; Columbus Dental, St. Louis, Mo) following the manufacturer’s recommended water/powder ratio and vacuum mixing time (Fig. 7D).
SUMMARY The objective of the implant splinting technique is to stabilize the impression copings during the subsequent clinical and laboratory impression transfer procedures and to minimize 3-D spatial relationship changes. The shim splinting technique introduced in the present technique report offers an alternative to previously reported approaches such as the block/ splinting approach. Moreover, the shim splinting technique has several advantages such as a simpler laboratory fabrication process, less patient chair time, and the need for fewer implant components.
REFERENCES 1. Assif D, Fenton A, Zarb G, Schmitt A. Comparative accuracy of implant impression procedures. Int J Periodontics Restorative Dent 1992;12:112-21. 2. Vigolo P, Majzoub Z, Cordioli G. Evaluation of the accuracy of three techniques used for multiple implant abutment impressions. J Prosthet Dent 2003;89:186-92. 3. Naconecy MM, Teixeira ER, Shinkai RS, Frasca LC, Cervieri A. Evaluation of the accuracy of 3 transfer techniques for implant-supported prostheses with multiple abutments. Int J Oral Maxillofac Implants 2004;19:192-8. 4. Del’Acqua MA, Chávez AM, Compagnoni MA, Molo Fde A Jr. Accuracy of impression techniques for an implant-supported prosthesis. Int J Oral Maxillofac Implants 2010;25:715-21.
5. Papaspyridakos P, Benic GI, Hogsett VL, White GS, Lal K, Gallucci GO. Accuracy of implant casts generated with splinted and non-splinted impression techniques for edentulous patients: an optical scanning study. Clin Oral Implants Res 2011; Jun 2 Doi: 10.1111/j. [Epub ahead of print] 6. Phillips KM, Nicholls JI. Ma T. The accuracy of three implant impression techniques: A three-dimensional analysis. Int J Oral Maxillofac Implants 1994;9:533-40. 7. Herbst D, Nel JC, Driessen CH, Becker PJ. Evaluation of impression accuracy for osseointegrated implant supported superstructures. J Prosthet Dent 2000;83:555-61. 8. Lee H, So JS, Hochstedler JL, Ercoli C. The accuracy of implant impressions: A systematic review. J Prosthet Dent 2008;100:285-91. 9. Brånemark PI, Zarb GA, Alberktsson T, editors. Tissue integrated prostheses: osseointegration in clinical dentistry. Chicago: Quintessence Publishing Co; 1985. p. 251-7. 10.Spector MR, Donovan TE, Nicholls JI. An evaluation of impression techniques for osseointegrated implants. J Prosthet Dent 1990;63:444-7. 11.Mojon P, Oberholzer JP, Meyer JM, Belser UC. Polymerization shrinkage of index and pattern acrylic resins. J Prosthet Dent 1990;64:684-8. 12.Ivanhoe JR, Adrian ED, Krantz WA, Edge MJ. An impression technique for osseointegrated implants. J Prosthet Dent 1991;66:410-1. 13.Hickey JC, Zarb GA, Bolender CL. Boucher’s prosthodontics treatment for edentulous patients. 9th ed. St. Louis: The C.V. Mosby Co; 1985. p. 155-61. Corresponding author: Dr. Junping Ma University of Washington Department of Restorative Dentistry 1959 NE Pacific Street, Box 357456 Seattle, Washington 98195 Fax: 206-543-7783 E-mail: [email protected] Copyright © 2012 by the Editorial Council for The Journal of Prosthetic Dentistry.
The Journal of Prosthetic Dentistry
Ma and Rubenstein
lation and rotation of the transfer copings within an impression when the impression is detached from the implants followed by placement of the implant analogs. Spector et al10 discussed potential problems associated with the splint technique, such as distortion of the splint materials and fracture of the connection between the splint material and the impression copings. Mojon et al11 determined that the polymerization shrinkage of acrylic resin (DuraLay; Reliance Dental Mfg Co, Worth, Ill) at 24 hours was 7% to 9%, and most shrinkage (80%) occurred within 17 minutes when materials were mixed at room temperature. The accuracy of the splinting technique described by Brånemark was questioned. Since then, many attempts have
1 Mandibular edentulous arch with 6 implants.
Resident, Graduate Prosthodontics, Department of Restorative Dentistry. Professor, Department of Restorative Dentistry, Division of Prosthodontics.
a
b
Ma and Rubenstein
been made to overcome the distortion generated by acrylic resin polymerization shrinkage. Ivanhoe et al12 proposed a now widely accepted block splinting technique, in which acrylic resin blocks are fabricated on a preliminary cast and connected intraorally before the definitive impression is made. Vigolo et al2 described the protocol of the block splinting impression technique in more detail. In their approach, the acrylic resin blocks should be prepared 1 day in advance, and the final connection should be made just before the impression procedure. In this way, the influence of polymerization shrinkage is minimized. Building on the existing body of research into splinting technique, an alternative splinting technique has
406
Volume 107 Issue 6
been developed and successfully demonstrated. This alternative technique provides the advantages of the conventional splinting technique and reduces both laboratory and clinic time. Moreover, the alternative technique uses only 1 set of implant impression copings and analogs as opposed to the 2 sets needed for the conventional block splinting technique. This article
introduces a splint technique that uses the shim method, which has been demonstrated to reduce laboratory time and patient chair time, the number of impression copings and laboratory analogs needed, and the ultimate cost. In the scenario presented an implant-supported prosthesis for the edentulous mandibular arch opposed by a maxillary complete denture was
fabricated (Fig. 1). Four implants placed between the mental foramina (3.75 × 10 mm RP; Replace Nobel Biocare USA, Yorba Linda, Calif ) retained the fixed implant prosthesis, and 2 implants (4.0 × 10 mm WP; Replace Nobel Biocare USA) positioned in the first molar areas served as distal stops. The splinting method to make a definitive impression is described.
A
B
C
D
E
F
2 A, Preliminary irreversible hydrocolloid impression of 6 implant impression copings. B, Inject thin mix of acrylic resin inside impression coping sites. C, Preliminary cast. D, Loosely cover impression copings with vinyl tubing. E, Wrap vinyl tubing with light polymerizing acrylic resin material and light polymerize. F, Shim fits around impression copings passively.
The Journal of Prosthetic Dentistry
Ma and Rubenstein
407
June 2012 TECHNIQUE 1. Remove the healing abutments, irrigate the internal connection/ threads of each implant, and secure 6 open tray impression copings (Nobel Biocare, USA) to the implants to a preload of 15 Ncm with a torque wrench (Nobel Biocare, USA). Make a pre-
liminary impression with irreversible hydrocolloid material (Jeltrate; Dentsply Caulk, Milford, Del) with a metal impression tray (Rim-Lock Impression Tray; Dentsply Caulk (Fig. 2A). 2. After recovering the preliminary impression, remove the impression copings and place the healing abutments back on each implant. Store the
impression copings in the order they were placed at each implant site for the definitive impression procedure. 3. Load a disposable syringe (Monoject 412 Syringe; Salvin Dental, Charlotte, NC) with a thin mix of autopolymerizing acrylic resin (1 part polymer: 2 parts monomer) (Pattern Resin; GC Corp, Tokyo, Ja-
A
B
3 A, Facial view of open-top custom tray. B, Occlusal view of open-top custom tray. Shim, custom tray and impression copings fit passively.
A
B 4 A, Acrylic resin placed around neck of impression copings. B, Complete seating of impression copings verified with radiograph (Right side) C, (Left side)
Ma and Rubenstein
C
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Volume 107 Issue 6
pan) and inject the material into the impression coping sites inside the preliminary impression (Fig. 2B). Once the acrylic resin replication of the impression copings has polymerized, pour the rest of the impression with die stone (Vel-Mix; Kerr Corp, Orange, Calif ) with a ratio of 22 mL of water to 110 g of stone mixed under vacuum for 30 seconds. 4. Recover the preliminary cast after the stone has set for 1 hour (Fig. 2C). 5. Cut pieces of vinyl tubing (TAP Plastics, Inc, Oakland, Calif ) with an internal diameter of 6 mm and an external diameter of 8 mm so that they fit with minimal gap space around each acrylic resin impression coping replication on the preliminary cast (Fig. 2D). 6. Wrap a light polymerizing acrylic resin tray material (Triad TruTray; Densply Trubyte, York, Penn) around the vinyl tubing. Light polymerize according to the manufacturer’s in-
structions (Fig. 2E). Remove the vinyl tubing and the light polymerizing resin shim from the preliminary cast and trim the shim to fit around the impression copings passively (Fig. 2F). 7. Place 1 layer of baseplate wax (Henry Schein Dental, Melville, NY) over the impression copings and the shim for uniform relief and then adapt 1 layer of aluminum foil before fabricating an open-top impression tray with the light polymerizing acrylic resin custom tray material. Ensure access to all of the acrylic resin implant copings is possible through the opening in the top of the tray. Reinforce the tray around the open-top area with another layer of the light polymerizing acrylic resin custom tray material to increase its rigidity. Once the optimal rigidity of the tray is achieved, trim the tray 1-2 mm short of the border extensions outlined on the preliminary cast (Fig. 3A). 8. Cut a sheet of rubber dam to
follow the arch form and punch holes in the rubber dam corresponding to each impression coping. Confirm the passive fit of the open-top custom tray and the shim around the plastic impression copings on the preliminary cast (Fig. 3B). 9. Before the definitive impression appointment, place a layer of acrylic resin (Pattern Resin; GC Corp) around the neck of the impression copings. Remove the healing abutments and secure the modified impression copings on each implant and preload to 15 Ncm with the torque driver. (Fig. 4A) Verify the complete seating of each impression coping with periapical radiographs. (Fig. 4B, 4C) 10. Place the rubber dam and shim around the impression copings (Fig. 5A). Apply auto polymerizing acrylic resin around the impression copings by using a powder/liquid brush application technique with a camel hair brush (No. 000; Kolinski Rembrandt,
A
B
C
D
5 A, Place rubber dam and shim around impression copings. B, Lute shim and impression copings with acrylic resin. C, All impression copings luted to shim. D, Reinforce shim splinting framework after initial acrylic resin has polymerized.
The Journal of Prosthetic Dentistry
Ma and Rubenstein
409
June 2012 Apeldoorn, Netherlands) (Fig. 5B). Start the luting sequence from the central implant. Once the shim is polymerized to this site proceed to every other one until all the impression copings are attached to the light polymerizing resin shim with the acrylic resin (Fig. 5C). Reinforce the connection with the same auto polymerizing acrylic resin after each impression
coping site has completed the initial polymerization (Fig. 5D). Remove the rubber dam using a sharp scissor. 11. Evaluate the custom tray for border extension and border mold as in the conventional complete denture impression procedure13(Fig. 6A). Adapt 1 layer of baseplate wax on the open top of the tray. Confirm the accessibility of all the impression
copings’ guide pins by imprinting them into the underside of the wax cap. Then remove the tray, clean, dry, and coat adhesive (Impregum; ESPE, Seefeld, Germany) on the internal surface of the tray and over the compound on the borders. 12. Dispense medium viscosity impression material (Impregum; ESPE) into both an impression syringe and
A
B
6 A, Seal open-top tray with 1 layer of baseplate wax. Imprint each guide pin on wax lid. B, Seat impression tray such that all guide pins contact underside of wax lid.
A
B
C
D
7 A, Intaglio surface of impression. B, Torque each implant replica onto impression copings to 15 Ncm while using hemostat to countertorque. C, Place silicone soft tissue moulage around each implant replica. D, Definitive cast.
Ma and Rubenstein
410
Volume 107 Issue 6 the custom tray. Inject the impression material around the splinted impression copings/shim and seat the impression tray such that all the guide pins contact the underside of the wax lid (Fig. 6B). Remove the wax lid after the impression material has polymerized, unscrew the guide pins, making sure they no longer engage the internal threads of each implant, and then recover the impression tray from the mouth (Fig. 7A). Replace the healing abutments on each implant. 13. Torque each implant replica onto the impression coping to 15 Ncm while using a hemostat engaging the base of the replica to provide countertorque (Fig. 7B). Place silicone soft tissue moulage (Softissue Moulage; Kerr Dental Laboratory, Orange, Calif ) around the implant replicas (Fig. 7C). Box the definitive impression with a 50:50 mixture of plaster and pumice. Pour with die stone (Die Keen; Columbus Dental, St. Louis, Mo) following the manufacturer’s recommended water/powder ratio and vacuum mixing time (Fig. 7D).
SUMMARY The objective of the implant splinting technique is to stabilize the impression copings during the subsequent clinical and laboratory impression transfer procedures and to minimize 3-D spatial relationship changes. The shim splinting technique introduced in the present technique report offers an alternative to previously reported approaches such as the block/ splinting approach. Moreover, the shim splinting technique has several advantages such as a simpler laboratory fabrication process, less patient chair time, and the need for fewer implant components.
REFERENCES 1. Assif D, Fenton A, Zarb G, Schmitt A. Comparative accuracy of implant impression procedures. Int J Periodontics Restorative Dent 1992;12:112-21. 2. Vigolo P, Majzoub Z, Cordioli G. Evaluation of the accuracy of three techniques used for multiple implant abutment impressions. J Prosthet Dent 2003;89:186-92. 3. Naconecy MM, Teixeira ER, Shinkai RS, Frasca LC, Cervieri A. Evaluation of the accuracy of 3 transfer techniques for implant-supported prostheses with multiple abutments. Int J Oral Maxillofac Implants 2004;19:192-8. 4. Del’Acqua MA, Chávez AM, Compagnoni MA, Molo Fde A Jr. Accuracy of impression techniques for an implant-supported prosthesis. Int J Oral Maxillofac Implants 2010;25:715-21.
5. Papaspyridakos P, Benic GI, Hogsett VL, White GS, Lal K, Gallucci GO. Accuracy of implant casts generated with splinted and non-splinted impression techniques for edentulous patients: an optical scanning study. Clin Oral Implants Res 2011; Jun 2 Doi: 10.1111/j. [Epub ahead of print] 6. Phillips KM, Nicholls JI. Ma T. The accuracy of three implant impression techniques: A three-dimensional analysis. Int J Oral Maxillofac Implants 1994;9:533-40. 7. Herbst D, Nel JC, Driessen CH, Becker PJ. Evaluation of impression accuracy for osseointegrated implant supported superstructures. J Prosthet Dent 2000;83:555-61. 8. Lee H, So JS, Hochstedler JL, Ercoli C. The accuracy of implant impressions: A systematic review. J Prosthet Dent 2008;100:285-91. 9. Brånemark PI, Zarb GA, Alberktsson T, editors. Tissue integrated prostheses: osseointegration in clinical dentistry. Chicago: Quintessence Publishing Co; 1985. p. 251-7. 10.Spector MR, Donovan TE, Nicholls JI. An evaluation of impression techniques for osseointegrated implants. J Prosthet Dent 1990;63:444-7. 11.Mojon P, Oberholzer JP, Meyer JM, Belser UC. Polymerization shrinkage of index and pattern acrylic resins. J Prosthet Dent 1990;64:684-8. 12.Ivanhoe JR, Adrian ED, Krantz WA, Edge MJ. An impression technique for osseointegrated implants. J Prosthet Dent 1991;66:410-1. 13.Hickey JC, Zarb GA, Bolender CL. Boucher’s prosthodontics treatment for edentulous patients. 9th ed. St. Louis: The C.V. Mosby Co; 1985. p. 155-61. Corresponding author: Dr. Junping Ma University of Washington Department of Restorative Dentistry 1959 NE Pacific Street, Box 357456 Seattle, Washington 98195 Fax: 206-543-7783 E-mail: [email protected] Copyright © 2012 by the Editorial Council for The Journal of Prosthetic Dentistry.
The Journal of Prosthetic Dentistry
Ma and Rubenstein