DENTAL TECHNIQUE
CAD/CAM-fabricated template for locating implant abutment screws in cement-retained anatomic zirconia restorations Du-Hyeong Lee, DDS, MSc Computer-aided design and ABSTRACT computer-assisted manufacCurrently, appropriate access to the abutment screw within cement-retained implant restorations is turing (CAD/CAM) technology determined using labor-intensive techniques. The introduction of computer-aided design/comhas revolutionized the proputer-aided manufacture technology has facilitated a digitized fabrication process to yield a temcesses that underpins dental plate that can enhance the accuracy of drilling a screw channel. This article describes the method implant surgery and restoraused to create these guide templates by using advanced dental design programs and machining. (J Prosthet Dent 2015;-:---) tion.1 Using CAD/CAM, restorations can be efficiently and accurately produced, an improvement over what has of the abutment or radiographs showing the implant traditionally been a complex and labor-intensive proposition provide useful data as to the position of the cess.2,3 The use of CAD software also facilitates rapid and screw.12,13 Staining a small spot on the restoration, precise fabrication of a mirror-image restoration, yielding which indicates the abutment position, also can be used the symmetry required for optimum esthetics.4 The latest to determine the starting point for drilling.14 A more milling units produce restorations that are of the best advanced system uses a drilling guide with a vacuumquality, with enhanced reproducibility of their intaglio formed template and a small hole that guides the and occlusal surfaces.5 angulation of the dental bur and serves as the starting Through enhanced precision of digital technologies, point for drilling.15-17 the use of CAD/CAM allows dentists to provide preAlthough several dental prosthetic and surgical prodictable and reliable restorations to their patients,6 cedures have become highly digitized, all methods while mitigating the risk of complications related to commonly used to locate the abutment screw in cementimplant surgery.7 Nonguided surgery for implant placeretained implant restorations have relied on conventional ment, particularly in the posterior maxilla, is riskier techniques. We used a method featuring CAD/CAM than computer-guided surgery.8 CAD/CAM technolto establish a technique for creating a drilling guide to ogy has also revolutionized the fabrication of polymerlocate the screw channel in cement-retained implant based interim restorations and complete removable restorations. prostheses.9-11 TECHNIQUE Frequently, removal of cement-retained implant restorations is required in patients with a loose or fractured abutment screw; this necessitates drilling a screw 1. Screw the scan body (same manufacturer as the channel. Several established techniques aid in locating implant) into position on the implant analog on the the approximate screw position within the implant cast (Fig. 1). Scan the cast using a desktop scanner restoration. Intraoral photographs marking the location (Ceramill Map 400; Amann Girrbach) to create a
Assistant Professor, Department of Prosthodontics, School of Dentistry and Advanced Dental Device Development Institute, Kyungpook National University, Daegu, South Korea.
THE JOURNAL OF PROSTHETIC DENTISTRY
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2
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Figure 1. Placement of scan body on implant replica on definitive stone cast.
Figure 2. Designing implant abutment over virtual cast.
Figure 3. Insertion of column indicating position and angulation of abutment screw.
Figure 4. Drawing of guide on virtual cast with dental CAD program. CAD, computer-aided design.
Figure 5. Designing guide for drilling screw access hole.
Figure 6. Guide fabricated with machining process.
virtual model. Alternatively, use an intraoral scanner to directly create the virtual model. 2. Design an implant abutment over the virtual model using a CAD program (Ceramill Match 2; Amann Girrbach) (Fig. 2). 3. Design the restoration. Design a column by extending the abutment screw channel (Fig. 3) and save the individual parts (model, abutment, restoration, and column) as a combined surface tessellation language (STL) file. THE JOURNAL OF PROSTHETIC DENTISTRY
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4. Open the STL file in a program for guide design (DDS-Pro 0.9.75; Digital Dental Service). Define a standard plane and set a region for the guide template (Fig. 4). 5. Design a virtual drilling guide using the “create drill guide” function of the program (Fig. 5). 6. Fabricate the guide template for drilling a screw channel using an additive or a subtractive machining process (Fig. 6). Lee
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2015
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DISCUSSION
REFERENCES
The method described uses CAD/CAM to produce a guide template to determine the screw drilling site in cement-retained implant restorations. Implant restorations are divided into 2 categories: monolithic (anatomic zirconia or metal) and multilayered (layered ceramic or metal ceramic). Because the anatomic zirconia restoration is fabricated directly using CAD/ CAM, the shape of the definitive restoration is almost identical to the designed image. The technique described in this article for fabricating a drill guide is based on the virtual image from the CAD program; therefore, the drill guide fits well on the definitive anatomic zirconia restoration. However, a multilayered restoration involves a manual porcelain layering process that changes the shape of the restoration with respect to the designed image. Accordingly, the drill guide template may not be used for multilayered restorations. In the clinical setting, when the abutment screw loosens or a fracture occurs, the general technique for assessing the screw involves sectioning the crown. However, damage to the abutment is likely during crown sectioning. The use of a drill guide can minimize the discomfort of both clinicians and patients. The additional costs incurred for laboratory work will be partly compensated by the continuous use and maintenance of the abutment. Furthermore, the continued use of the crown is occasionally possible for molars, thus avoiding the additional costs of new abutments and restorations. Benefits and costs should be considered in the decision to use a drill guide.
1. Miyazaki T, Hotta Y, Kunii J, Kuriyama S, Tamaki Y. A review of dental CAD/ CAM: current status and future perspectives from 20 years of experience. Dent Mater J 2009;28:44-56. 2. Reiss B. Clinical results of Cerec inlays in a dental practice over a period of 18 years. Int J Comput Dent 2006;9:11-22. 3. Euan R, Figueras-Alvarez O, Cabratosa-Termes J, Oliver-Parra R. Marginal adaptation of zirconium dioxide copings: influence of the CAD/CAM system and the finish line design. J Prosthet Dent 2014;112: 155-62. 4. Cho SH, Chang WG. Mirror-image anterior crown fabrication with computer-aided design and rapid prototyping technology: a clinical report. J Prosthet Dent 2013;109:75-8. 5. Bosch G, Ender A, Mehl A. A 3-dimensional accuracy analysis of chairside CAD/CAM milling processes. J Prosthet Dent 2014;112:1425-31. 6. LeSage B. Direct composite resin layering techniques for creating lifelike CAD/CAM fabricated composite resin veneers and crowns. J Prosthet Dent 2014;112:5-8. 7. Arisan V, Karabuda CZ, Ozdemir T. Implant surgery using boneand mucosa-supported stereolithographic guides in totally edentulous jaws: surgical and post-operative outcomes of computer-aided vs. standard techniques. Clin Oral Implants Res 2010;21:980-8. 8. Noharet R, Pettersson A, Bourgeois D. Accuracy of implant placement in the posterior maxilla as related to 2 types of surgical guides: a pilot study in the human cadaver. J Prosthet Dent 2014;112:526-32. 9. Infante L, Yilmaz B, McGlumphy E, Finger I. Fabricating complete dentures with CAD/CAM technology. J Prosthet Dent 2014;111:351-5. 10. Kanazawa M, Iwaki M, Minakuchi S, Nomura N. Fabrication of titanium alloy frameworks for complete dentures by selective laser melting. J Prosthet Dent 2014;112:1441-7. 11. Kurbad A. CAD/CAM-based polymer provisionals as treatment adjuncts. Int J Comput Dent 2013;16:327-46. 12. Figueras-Alvarez O, Cano-Batalla J. An alternative method for registering the abutment screw position of cement-retained implant restoration. J Prosthet Dent 2014;112:1304-5. 13. Patil PG. A technique for repairing a loosening abutment screw for a cementretained implant prosthesis. J Prosthodont 2011;20:652-5. 14. Schwedhelm ER, Raigrodski AJ. A technique for locating implant abutment screws of posterior cement-retained metal-ceramic restorations with ceramic occlusal surfaces. J Prosthet Dent 2006;95:165-7. 15. Lautensack J, Weber V, Wolfart S. Template to determine the position and angulation of theabutment screw channel for implant-supported, cementretained restorations. J Prosthet Dent 2012;107:134-6. 16. Tarlow JL. A modified technique to locate the abutment screw access opening of a cemented implant-supported restoration. J Prosthet Dent 2012;108:58-9. 17. Wadhwani C, Chung KH. Simple device for locating the abutment screw position of a cement-retained implant restoration. J Prosthet Dent 2013;109:272-4.
SUMMARY This article details how dental design programs and machining can be used in combination to fabricate a template for drilling a screw channel in cement-retained, solid zirconia restorations. The proposed technique not only improves the accuracy of drilling but also reduces labor-intensive tasks. Moreover, because the guide can be repeatedly fabricated as required from existing design data, clinicians do not need to fabricate and store it for future use. The introduction of CAD/CAM systems for the fabrication of screw channel drilling guides will prove advantageous to both patients and clinicians.
Lee
Corresponding author: Dr Du-Hyeong Lee Kyungpook National University 2175 Dalgubeoldae-ro, Jung-Gu, Daegu 700-705 SOUTH KOREA Email: [email protected] Acknowledgments The author thanks Kyung-Rok Kim for contributions and assistance in laboratory work during this experiment. Copyright © 2015 by the Editorial Council for The Journal of Prosthetic Dentistry.
THE JOURNAL OF PROSTHETIC DENTISTRY
CAD/CAM-fabricated template for locating implant abutment screws in cement-retained anatomic zirconia restorations Du-Hyeong Lee, DDS, MSc Computer-aided design and ABSTRACT computer-assisted manufacCurrently, appropriate access to the abutment screw within cement-retained implant restorations is turing (CAD/CAM) technology determined using labor-intensive techniques. The introduction of computer-aided design/comhas revolutionized the proputer-aided manufacture technology has facilitated a digitized fabrication process to yield a temcesses that underpins dental plate that can enhance the accuracy of drilling a screw channel. This article describes the method implant surgery and restoraused to create these guide templates by using advanced dental design programs and machining. (J Prosthet Dent 2015;-:---) tion.1 Using CAD/CAM, restorations can be efficiently and accurately produced, an improvement over what has of the abutment or radiographs showing the implant traditionally been a complex and labor-intensive proposition provide useful data as to the position of the cess.2,3 The use of CAD software also facilitates rapid and screw.12,13 Staining a small spot on the restoration, precise fabrication of a mirror-image restoration, yielding which indicates the abutment position, also can be used the symmetry required for optimum esthetics.4 The latest to determine the starting point for drilling.14 A more milling units produce restorations that are of the best advanced system uses a drilling guide with a vacuumquality, with enhanced reproducibility of their intaglio formed template and a small hole that guides the and occlusal surfaces.5 angulation of the dental bur and serves as the starting Through enhanced precision of digital technologies, point for drilling.15-17 the use of CAD/CAM allows dentists to provide preAlthough several dental prosthetic and surgical prodictable and reliable restorations to their patients,6 cedures have become highly digitized, all methods while mitigating the risk of complications related to commonly used to locate the abutment screw in cementimplant surgery.7 Nonguided surgery for implant placeretained implant restorations have relied on conventional ment, particularly in the posterior maxilla, is riskier techniques. We used a method featuring CAD/CAM than computer-guided surgery.8 CAD/CAM technolto establish a technique for creating a drilling guide to ogy has also revolutionized the fabrication of polymerlocate the screw channel in cement-retained implant based interim restorations and complete removable restorations. prostheses.9-11 TECHNIQUE Frequently, removal of cement-retained implant restorations is required in patients with a loose or fractured abutment screw; this necessitates drilling a screw 1. Screw the scan body (same manufacturer as the channel. Several established techniques aid in locating implant) into position on the implant analog on the the approximate screw position within the implant cast (Fig. 1). Scan the cast using a desktop scanner restoration. Intraoral photographs marking the location (Ceramill Map 400; Amann Girrbach) to create a
Assistant Professor, Department of Prosthodontics, School of Dentistry and Advanced Dental Device Development Institute, Kyungpook National University, Daegu, South Korea.
THE JOURNAL OF PROSTHETIC DENTISTRY
1
2
Volume
-
Issue
Figure 1. Placement of scan body on implant replica on definitive stone cast.
Figure 2. Designing implant abutment over virtual cast.
Figure 3. Insertion of column indicating position and angulation of abutment screw.
Figure 4. Drawing of guide on virtual cast with dental CAD program. CAD, computer-aided design.
Figure 5. Designing guide for drilling screw access hole.
Figure 6. Guide fabricated with machining process.
virtual model. Alternatively, use an intraoral scanner to directly create the virtual model. 2. Design an implant abutment over the virtual model using a CAD program (Ceramill Match 2; Amann Girrbach) (Fig. 2). 3. Design the restoration. Design a column by extending the abutment screw channel (Fig. 3) and save the individual parts (model, abutment, restoration, and column) as a combined surface tessellation language (STL) file. THE JOURNAL OF PROSTHETIC DENTISTRY
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4. Open the STL file in a program for guide design (DDS-Pro 0.9.75; Digital Dental Service). Define a standard plane and set a region for the guide template (Fig. 4). 5. Design a virtual drilling guide using the “create drill guide” function of the program (Fig. 5). 6. Fabricate the guide template for drilling a screw channel using an additive or a subtractive machining process (Fig. 6). Lee
-
2015
3
DISCUSSION
REFERENCES
The method described uses CAD/CAM to produce a guide template to determine the screw drilling site in cement-retained implant restorations. Implant restorations are divided into 2 categories: monolithic (anatomic zirconia or metal) and multilayered (layered ceramic or metal ceramic). Because the anatomic zirconia restoration is fabricated directly using CAD/ CAM, the shape of the definitive restoration is almost identical to the designed image. The technique described in this article for fabricating a drill guide is based on the virtual image from the CAD program; therefore, the drill guide fits well on the definitive anatomic zirconia restoration. However, a multilayered restoration involves a manual porcelain layering process that changes the shape of the restoration with respect to the designed image. Accordingly, the drill guide template may not be used for multilayered restorations. In the clinical setting, when the abutment screw loosens or a fracture occurs, the general technique for assessing the screw involves sectioning the crown. However, damage to the abutment is likely during crown sectioning. The use of a drill guide can minimize the discomfort of both clinicians and patients. The additional costs incurred for laboratory work will be partly compensated by the continuous use and maintenance of the abutment. Furthermore, the continued use of the crown is occasionally possible for molars, thus avoiding the additional costs of new abutments and restorations. Benefits and costs should be considered in the decision to use a drill guide.
1. Miyazaki T, Hotta Y, Kunii J, Kuriyama S, Tamaki Y. A review of dental CAD/ CAM: current status and future perspectives from 20 years of experience. Dent Mater J 2009;28:44-56. 2. Reiss B. Clinical results of Cerec inlays in a dental practice over a period of 18 years. Int J Comput Dent 2006;9:11-22. 3. Euan R, Figueras-Alvarez O, Cabratosa-Termes J, Oliver-Parra R. Marginal adaptation of zirconium dioxide copings: influence of the CAD/CAM system and the finish line design. J Prosthet Dent 2014;112: 155-62. 4. Cho SH, Chang WG. Mirror-image anterior crown fabrication with computer-aided design and rapid prototyping technology: a clinical report. J Prosthet Dent 2013;109:75-8. 5. Bosch G, Ender A, Mehl A. A 3-dimensional accuracy analysis of chairside CAD/CAM milling processes. J Prosthet Dent 2014;112:1425-31. 6. LeSage B. Direct composite resin layering techniques for creating lifelike CAD/CAM fabricated composite resin veneers and crowns. J Prosthet Dent 2014;112:5-8. 7. Arisan V, Karabuda CZ, Ozdemir T. Implant surgery using boneand mucosa-supported stereolithographic guides in totally edentulous jaws: surgical and post-operative outcomes of computer-aided vs. standard techniques. Clin Oral Implants Res 2010;21:980-8. 8. Noharet R, Pettersson A, Bourgeois D. Accuracy of implant placement in the posterior maxilla as related to 2 types of surgical guides: a pilot study in the human cadaver. J Prosthet Dent 2014;112:526-32. 9. Infante L, Yilmaz B, McGlumphy E, Finger I. Fabricating complete dentures with CAD/CAM technology. J Prosthet Dent 2014;111:351-5. 10. Kanazawa M, Iwaki M, Minakuchi S, Nomura N. Fabrication of titanium alloy frameworks for complete dentures by selective laser melting. J Prosthet Dent 2014;112:1441-7. 11. Kurbad A. CAD/CAM-based polymer provisionals as treatment adjuncts. Int J Comput Dent 2013;16:327-46. 12. Figueras-Alvarez O, Cano-Batalla J. An alternative method for registering the abutment screw position of cement-retained implant restoration. J Prosthet Dent 2014;112:1304-5. 13. Patil PG. A technique for repairing a loosening abutment screw for a cementretained implant prosthesis. J Prosthodont 2011;20:652-5. 14. Schwedhelm ER, Raigrodski AJ. A technique for locating implant abutment screws of posterior cement-retained metal-ceramic restorations with ceramic occlusal surfaces. J Prosthet Dent 2006;95:165-7. 15. Lautensack J, Weber V, Wolfart S. Template to determine the position and angulation of theabutment screw channel for implant-supported, cementretained restorations. J Prosthet Dent 2012;107:134-6. 16. Tarlow JL. A modified technique to locate the abutment screw access opening of a cemented implant-supported restoration. J Prosthet Dent 2012;108:58-9. 17. Wadhwani C, Chung KH. Simple device for locating the abutment screw position of a cement-retained implant restoration. J Prosthet Dent 2013;109:272-4.
SUMMARY This article details how dental design programs and machining can be used in combination to fabricate a template for drilling a screw channel in cement-retained, solid zirconia restorations. The proposed technique not only improves the accuracy of drilling but also reduces labor-intensive tasks. Moreover, because the guide can be repeatedly fabricated as required from existing design data, clinicians do not need to fabricate and store it for future use. The introduction of CAD/CAM systems for the fabrication of screw channel drilling guides will prove advantageous to both patients and clinicians.
Lee
Corresponding author: Dr Du-Hyeong Lee Kyungpook National University 2175 Dalgubeoldae-ro, Jung-Gu, Daegu 700-705 SOUTH KOREA Email: [email protected] Acknowledgments The author thanks Kyung-Rok Kim for contributions and assistance in laboratory work during this experiment. Copyright © 2015 by the Editorial Council for The Journal of Prosthetic Dentistry.
THE JOURNAL OF PROSTHETIC DENTISTRY
