- Email: [email protected]
A workflow for fabricating a hollow obturator by using 3D digital technologies
DENTAL TECHNIQUE
A workflow for fabricating a hollow obturator by using 3D digital technologies Shigeto Koyama, DDS, PhD,a Hiroaki Kato, RDT, MS,b Takayuki Harata, RDT,c and Keiichi Sasaki, DDS, PhDd The fabrication of hollow ABSTRACT obturator prostheses requires Conventional methods used for fabricating hollow obturator prostheses have numerous problems. the implementation of comThe workflow presented in this article integrates 3D digital technologies into a functional protocol, plex techniques by highly enabling the fabrication of single-piece hollow prostheses with no joints by using an optical 3D skilled technicians. Such conscanner and a laminating molding device. (J Prosthet Dent 2019;-:---) ventional methods typically printing, selective laser sintering, selective laser melting, include the separate fabrication of the open part of the and fused deposition molding.17-21 The 3D optical obturator and the palatal part or canopy cover, followed shaping equipment used with RP techniques offers by the subsequent joining of these 2 parts at room significant advantages by allowing the fabrication of temperature by using autopolymerizing or adhesive single-piece hollow prostheses with no joints, thereby resins.1-9 However, poor adhesion between the parts or eliminating the limitations of traditional fabrication. the presence of air bubbles in the autopolymerizing resin However, optical laminate molding has only recently may result in water entering the inner space of the been used to fabricate removable dental prostheses, and obturator and deterioration of the joint. the authors are aware of only a few reports focusing on Digital technology is frequently used in the field of this method and almost none that explore the clinical dentistry to measure 3D digital shapes, create target application of the resulting appliances. Although the designs, and fabricate prosthetic devices.10-16 Current fabrication of completely integrated hollow obturator innovations and technological developments in prostheses is easier with optical laminate molding techcomputer-aided design and computer-aided manufacniques than with conventional methods, there is still ture (CAD-CAM) allow the design and manufacture of room for improvement. removable dental prostheses to be fully digitized.11 The present report describes the workflow of the However, CAD-CAM techniques are rarely used to fabrication of a maxillofacial prosthesis with a hollow fabricate hollow obturator prostheses because they are obturator by using an optical 3D scanner and a laminot suitable for a wide range of targets, such as soft tissue nating molding device. or maxillary defects. This means that large amounts of data and time are required to fabricate a completely integrated hollow prosthesis, the optimal type of obturator, TECHNIQUE and such prostheses cannot be fabricated using CADCAM systems at present. The fabrication of a maxillofacial prosthesis with a hollow Recently developed rapid prototyping (RP) obturator is simpler with newly developed digital techmanufacturing techniques have been introduced into nology than with conventional methods (Fig. 1). When dentistry. RP techniques include stereolithography, 3D 3D digital molding technology is used for fabrication, the
a
Associate Professor, Tohoku University Hospital, Maxillofacial Prosthetics Clinic, Sendai, Japan. Dental Technician Chief, Dental Laboratory, Tohoku University Hospital, Sendai, Japan. c Dental Technician, Dental Laboratory, Tohoku University Hospital, Sendai, Japan. d Professor, Division of Advanced Prosthodontics, Tohoku University Graduate School of Dentistry, Sendai, Japan. b
THE JOURNAL OF PROSTHETIC DENTISTRY
1
2
Volume
Conventional method
-
Issue
-
Digital technology method
Impression-interocclusal record
Wax denture shaping
3D scanning obturator 3D printing
Polymerization
Wax denture shaping
Obturator modeling
Polymerization
Sealing of obturator
Polishing and delivery
Figure 1. Comparison of fabrication of maxillary prosthesis with hollow obturator using conventional method and digital technology method.
hollow obturator part is fabricated first, followed by the remaining denture parts by using conventional methods. 1. Make an anatomic impression of the right hemimaxillectomy area and a definitive cast (Fig. 2A). Record the shape of the definitive cast, including the maxillary defect, with an optical 3D scanner (Rexcan DS2; Digital Scan 3D) and convert it to standard tessellation language (STL) data (Fig. 2B). 2. Transfer the STL data to the modeling software (Dental Lab Tools 4.0; 3D Systems) to obtain the obturator modeling data. Correct the defect portion with scanning. Using the modeling software, survey the attachment and removal direction of the obturator part and block out the created undercut area (Fig. 3A). 3. Design the hollow obturator part by using the modeling software (Fig. 3B). Extract the data for the entire obturator part leaving a 2-mm-thick outer border. Cut out the center to create data for a hollow obturator (Fig. 3C, 3D). 4. Use photopolymerizing acrylic resin (DS2000 Lot no. 30160427; DWS) and a laminate-type 3D photographic fabrication apparatus (DIGITAL WAX 020D; DWS) to construct the prosthesis based on the design data. Apply the hanging-type photographic fabrication system to remove the unpolymerized resin present inside during photopolymerization (Fig. 4). 5. After the completion of modeling, polymerize with ultraviolet light by irradiating the specimen for 20 THE JOURNAL OF PROSTHETIC DENTISTRY
Figure 2. Maxillary defect. A, Stone cast. B, Scanned image of cast acquired by 3D geometry measuring device.
minutes in a UV polymerization unit (UV Curing Unit model S2; DWS) to release the residual monomer. 6. Set a sprue on the canopy part in such a way that it will not affect the fit (Fig. 5). This is necessary because of the use of a molding device with a hanging-type laminating system. Cut and adjust the sprue by using tungsten carbide trimming burs (Rotary carbide 80049; Kerr) attached to the hollow obturator part so that it can be placed in the definitive cast. With the hollow obturator part returned to the definitive cast, arrange the artificial teeth and fabricate wax model dentures according to the conventional methods. Embed them in a denture flask using investing materials to perform wax elimination. 7. Extract the molded hollow obturator part from the bottom of the flask and apply a primer to strengthen the adhesion of the base acrylic resin with the part. After application, return the part to the bottom of the flask and fill with base acrylic resin. After microwave (RE-T2-W5; SHARP) polymerization at 500 W for 3 minutes, remove the maxillofacial prosthesis with the hollow obturator from the flasks, cut, and polish its surface according to the usual method. This completes the fabrication process (Fig. 6). Koyama et al
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2019
3
Figure 3. Generated STL data of hollow obturator. A, Blocking out undercut. B, Acquisition of hollow obturator data. C, Sampling of hollow obturator data. D, Cross-section of hollow obturator data. STL, standard tessellation language.
Figure 4. Molding process of hollow obturator using laminate-type 3D photo fabrication apparatus.
DISCUSSION Although various methods of fabricating closed hollow obturator prostheses have been proposed, issues remain, such as the joined part in the hollow section and the complex nature of the procedure. The application of the optical 3D scanner and the laminating molding device made it possible to fabricate a seamless hollow obturator with this technique. However, the overall structure of the hollow obturator was not fabricated using the optical laminate molding techniques because material with adequate mechanical strength, wear resistance, and esthetics for the denture components (artificial teeth and
Koyama et al
gingiva) is currently unavailable. To overcome the disadvantages of large amounts of data and time and to be practical in the presented workflow, the prosthesis was fabricated using a combination of optical laminate molding techniques and conventional fabrication methods. In the hanging-type photographic fabrication system used in this technique, a laser light was applied below the transparent acrylic resin container filled with photopolymerizing resin. The obturator part was fabricated by laminating the photopolymerization reaction while gradually elevating the platform after each round of photoirradiation and molding, thus allowing the unpolymerized resin present inside the part to be eliminated (Fig. 4). The laminating pitch for molding was set to 0.01 mm, and photoirradiation was performed by using the galvanometer scanner method, in which the high-speed optical axis of a superfine laser was moved while the position was maintained with 2 mirrors. This method of fabricating hollow obturators is more straightforward than the conventional method. With this approach, the thickness of the walls of the hollow obturator can be set arbitrarily. Also, the fact that it can be completely integrated with no joined component should help solve clinical problems such as contamination, malodor, and
THE JOURNAL OF PROSTHETIC DENTISTRY
4
Volume
-
Issue
-
Figure 5. Printing hollow obturator. A, Designing the sprue for printing. B, Printed hollow obturator after printing.
Figure 6. Definitive hollow maxillary obturator. A, Polished surface. B, Tissue surface.
decreased esthetic properties as a result of saliva and water entering the hollow part. The 3D method could also ensure that the thickness of the denture mucosal side is homogeneous; however, there is a risk of the dentures being too thick because of the use of the remaining alveolar ridge as a reference for the polishing side. Therefore, a contraindication would be patients requiring a light-weight prosthesis. Limitations of the technique include the possibility of incomplete polymerization of the interfacial layers and the possibility of unpolymerized monomers remaining in the hollow center. Studies are needed to determine the biostability of prostheses created with this method and to refine the design and develop a method of easily fabricating an entire prosthesis along with a hollow obturator using 3D digital technologies.
REFERENCES
SUMMARY A method applying optical laminate molding techniques can be used to fabricate single-piece hollow prostheses with no joints. Using the optical laminate molding techniques is a time-efficient method that conserves the integrity of the fabrication process without the modeling and sealing processes of conventional methods. THE JOURNAL OF PROSTHETIC DENTISTRY
1. Keyf F. Obturator prostheses for hemi-maxillectomy patients. J Oral Rehabil 2001;28:821-9. 2. Wu Y, Schaaf NG. Comparison of weight reduction in different designs of solid and hollow obturator prostheses. J Prosthet Dent 1989;62:214-7. 3. McAndrew KS, Rothenberger S, Minsley GE. An innovative investment method for the fabrication of a closed hollow obturator prosthesis. J Prosthet Dent 1998;80:129-32. 4. Habib BH, Driscoll CF. Fabrication of a closed hollow obturator. J Prosthet Dent 2004;91:383-5. 5. Buzayan MM, Ariffin YT, Yunus N. Closed hollow bulb obturator one-step fabrication: a clinical report. J Prosthodont 2013;22:591-5. 6. Patil PG, Patil SP. Fabrication of a hollow obturator as a single unit for management of bilateral subtotal maxillectomy. J Prosthodont 2012;21:194-9. 7. Padmanabhan TV, Kumar VA, Mohamed KK, Unnikrishnan N. Prosthetic rehabilitation of a maxillectomy with a two-piece hollow bulb obturator. A clinical report. J Prosthodont 2011;20:394-401. 8. Hori K, Miyamoto T, Ono T, Yamamoto M, Shiroshita N, Maeda Y, et al. One step polymerizing technique for fabricating a hollow obturator. J Prosthodont Res 2013;57:294-7. 9. Kocacikli M, Yalug S, Yazicioglu H, Yilmaz C. Fabricating a hollow obturator with visible light-cured resin system. J Prosthodont 2008;17:596-8. 10. Van der Zande MM, Gorter RC, Aartman IH, Wismeijer D. Adoption and use of digital technologies among general dental practitioners in the Netherlands. PLoS One 2015;10:e0120725. 11. Bilgin MS, Baytaro glu EN, Erdem A, Dilber E. A review of computer-aided design/computer-aided manufacture techniques for removable denture fabrication. Eur J Dent 2016;10:286-91. 12. Marinello C. The digital revolution’s impact on prosthodontics. Int J Prosthodont 2015;29:431-3. 13. Schwindling FS, Stober T. A comparison of two digital techniques for the fabrication of complete removable dental prostheses: A pilot clinical study. J Prosthet Dent 2016;116:756-63. 14. Schweiger J, Guth JF, Edelhoff D, Stumbaum J. Virtual evaluation for CADCAM-fabricated complete dentures. J Prosthet Dent 2017;117:28-33. 15. Wimmer T, Gallus K, Eichberger M, Stawarczyk B. Complete denture fabrication supported by CAD/CAM. J Prosthet Dent 2016;116:541-6.
Koyama et al
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2019
16. Jiang FF, Hou Y, Lu L, Ding XX, Li W, Yan AH. Functional evaluation of a CAD/ CAM prosthesis for immediate defect repair after total maxillectomy: a case series of 18 patients with maxillary sinus cancer. J Esthet Restor Dent 2015;1:80-9. 17. Jiao T, Zhu C, Dong X, Gu X. Rehabilitation of maxillectomy defects with obturator prostheses fabricated using computer-aided design and rapid prototyping: a pilot study. Int J Prosthodont 2014;27:480-6. 18. Kim MS, Lee JY, Shin SW. Fabricating an obturator using rapid prototyping to design the framework: a case report. Int J Prosthodont 2014;27:439-41. 19. Rodney J, Chicchon I. Digital design and fabrication of surgical obturators based only on preoperative computed tomography data. Int J Prosthodont 2017;30:111-2. 20. Torabi K, Farjood E, Hamedanib S. Rapid prototyping technologies and their applications in prosthodontics, a review of literature. J Dent 2015;16:1-9. 21. Wu J, Li Y, Zhang Y. Use of intraoral scanning and 3-dimensional printing in the fabrication of a removable partial denture for a patient with limited mouth opening. J Am Dent Assoc 2017;148:338-41.
Koyama et al
5
Corresponding author: Dr Shigeto Koyama Tohoku University Hospital Maxillofacial Prosthetics Clinic 4-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi 980-8575 JAPAN Email: [email protected] Acknowledgments The authors thank Dr Kuniyuki Izumita and Dr Takehiko Mito for assistance in laboratory processing and data collection. The authors also thank Enago for English language editing services. Copyright © 2019 by the Editorial Council for The Journal of Prosthetic Dentistry. https://doi.org/10.1016/j.prosdent.2019.05.020
THE JOURNAL OF PROSTHETIC DENTISTRY
A workflow for fabricating a hollow obturator by using 3D digital technologies Shigeto Koyama, DDS, PhD,a Hiroaki Kato, RDT, MS,b Takayuki Harata, RDT,c and Keiichi Sasaki, DDS, PhDd The fabrication of hollow ABSTRACT obturator prostheses requires Conventional methods used for fabricating hollow obturator prostheses have numerous problems. the implementation of comThe workflow presented in this article integrates 3D digital technologies into a functional protocol, plex techniques by highly enabling the fabrication of single-piece hollow prostheses with no joints by using an optical 3D skilled technicians. Such conscanner and a laminating molding device. (J Prosthet Dent 2019;-:---) ventional methods typically printing, selective laser sintering, selective laser melting, include the separate fabrication of the open part of the and fused deposition molding.17-21 The 3D optical obturator and the palatal part or canopy cover, followed shaping equipment used with RP techniques offers by the subsequent joining of these 2 parts at room significant advantages by allowing the fabrication of temperature by using autopolymerizing or adhesive single-piece hollow prostheses with no joints, thereby resins.1-9 However, poor adhesion between the parts or eliminating the limitations of traditional fabrication. the presence of air bubbles in the autopolymerizing resin However, optical laminate molding has only recently may result in water entering the inner space of the been used to fabricate removable dental prostheses, and obturator and deterioration of the joint. the authors are aware of only a few reports focusing on Digital technology is frequently used in the field of this method and almost none that explore the clinical dentistry to measure 3D digital shapes, create target application of the resulting appliances. Although the designs, and fabricate prosthetic devices.10-16 Current fabrication of completely integrated hollow obturator innovations and technological developments in prostheses is easier with optical laminate molding techcomputer-aided design and computer-aided manufacniques than with conventional methods, there is still ture (CAD-CAM) allow the design and manufacture of room for improvement. removable dental prostheses to be fully digitized.11 The present report describes the workflow of the However, CAD-CAM techniques are rarely used to fabrication of a maxillofacial prosthesis with a hollow fabricate hollow obturator prostheses because they are obturator by using an optical 3D scanner and a laminot suitable for a wide range of targets, such as soft tissue nating molding device. or maxillary defects. This means that large amounts of data and time are required to fabricate a completely integrated hollow prosthesis, the optimal type of obturator, TECHNIQUE and such prostheses cannot be fabricated using CADCAM systems at present. The fabrication of a maxillofacial prosthesis with a hollow Recently developed rapid prototyping (RP) obturator is simpler with newly developed digital techmanufacturing techniques have been introduced into nology than with conventional methods (Fig. 1). When dentistry. RP techniques include stereolithography, 3D 3D digital molding technology is used for fabrication, the
a
Associate Professor, Tohoku University Hospital, Maxillofacial Prosthetics Clinic, Sendai, Japan. Dental Technician Chief, Dental Laboratory, Tohoku University Hospital, Sendai, Japan. c Dental Technician, Dental Laboratory, Tohoku University Hospital, Sendai, Japan. d Professor, Division of Advanced Prosthodontics, Tohoku University Graduate School of Dentistry, Sendai, Japan. b
THE JOURNAL OF PROSTHETIC DENTISTRY
1
2
Volume
Conventional method
-
Issue
-
Digital technology method
Impression-interocclusal record
Wax denture shaping
3D scanning obturator 3D printing
Polymerization
Wax denture shaping
Obturator modeling
Polymerization
Sealing of obturator
Polishing and delivery
Figure 1. Comparison of fabrication of maxillary prosthesis with hollow obturator using conventional method and digital technology method.
hollow obturator part is fabricated first, followed by the remaining denture parts by using conventional methods. 1. Make an anatomic impression of the right hemimaxillectomy area and a definitive cast (Fig. 2A). Record the shape of the definitive cast, including the maxillary defect, with an optical 3D scanner (Rexcan DS2; Digital Scan 3D) and convert it to standard tessellation language (STL) data (Fig. 2B). 2. Transfer the STL data to the modeling software (Dental Lab Tools 4.0; 3D Systems) to obtain the obturator modeling data. Correct the defect portion with scanning. Using the modeling software, survey the attachment and removal direction of the obturator part and block out the created undercut area (Fig. 3A). 3. Design the hollow obturator part by using the modeling software (Fig. 3B). Extract the data for the entire obturator part leaving a 2-mm-thick outer border. Cut out the center to create data for a hollow obturator (Fig. 3C, 3D). 4. Use photopolymerizing acrylic resin (DS2000 Lot no. 30160427; DWS) and a laminate-type 3D photographic fabrication apparatus (DIGITAL WAX 020D; DWS) to construct the prosthesis based on the design data. Apply the hanging-type photographic fabrication system to remove the unpolymerized resin present inside during photopolymerization (Fig. 4). 5. After the completion of modeling, polymerize with ultraviolet light by irradiating the specimen for 20 THE JOURNAL OF PROSTHETIC DENTISTRY
Figure 2. Maxillary defect. A, Stone cast. B, Scanned image of cast acquired by 3D geometry measuring device.
minutes in a UV polymerization unit (UV Curing Unit model S2; DWS) to release the residual monomer. 6. Set a sprue on the canopy part in such a way that it will not affect the fit (Fig. 5). This is necessary because of the use of a molding device with a hanging-type laminating system. Cut and adjust the sprue by using tungsten carbide trimming burs (Rotary carbide 80049; Kerr) attached to the hollow obturator part so that it can be placed in the definitive cast. With the hollow obturator part returned to the definitive cast, arrange the artificial teeth and fabricate wax model dentures according to the conventional methods. Embed them in a denture flask using investing materials to perform wax elimination. 7. Extract the molded hollow obturator part from the bottom of the flask and apply a primer to strengthen the adhesion of the base acrylic resin with the part. After application, return the part to the bottom of the flask and fill with base acrylic resin. After microwave (RE-T2-W5; SHARP) polymerization at 500 W for 3 minutes, remove the maxillofacial prosthesis with the hollow obturator from the flasks, cut, and polish its surface according to the usual method. This completes the fabrication process (Fig. 6). Koyama et al
-
2019
3
Figure 3. Generated STL data of hollow obturator. A, Blocking out undercut. B, Acquisition of hollow obturator data. C, Sampling of hollow obturator data. D, Cross-section of hollow obturator data. STL, standard tessellation language.
Figure 4. Molding process of hollow obturator using laminate-type 3D photo fabrication apparatus.
DISCUSSION Although various methods of fabricating closed hollow obturator prostheses have been proposed, issues remain, such as the joined part in the hollow section and the complex nature of the procedure. The application of the optical 3D scanner and the laminating molding device made it possible to fabricate a seamless hollow obturator with this technique. However, the overall structure of the hollow obturator was not fabricated using the optical laminate molding techniques because material with adequate mechanical strength, wear resistance, and esthetics for the denture components (artificial teeth and
Koyama et al
gingiva) is currently unavailable. To overcome the disadvantages of large amounts of data and time and to be practical in the presented workflow, the prosthesis was fabricated using a combination of optical laminate molding techniques and conventional fabrication methods. In the hanging-type photographic fabrication system used in this technique, a laser light was applied below the transparent acrylic resin container filled with photopolymerizing resin. The obturator part was fabricated by laminating the photopolymerization reaction while gradually elevating the platform after each round of photoirradiation and molding, thus allowing the unpolymerized resin present inside the part to be eliminated (Fig. 4). The laminating pitch for molding was set to 0.01 mm, and photoirradiation was performed by using the galvanometer scanner method, in which the high-speed optical axis of a superfine laser was moved while the position was maintained with 2 mirrors. This method of fabricating hollow obturators is more straightforward than the conventional method. With this approach, the thickness of the walls of the hollow obturator can be set arbitrarily. Also, the fact that it can be completely integrated with no joined component should help solve clinical problems such as contamination, malodor, and
THE JOURNAL OF PROSTHETIC DENTISTRY
4
Volume
-
Issue
-
Figure 5. Printing hollow obturator. A, Designing the sprue for printing. B, Printed hollow obturator after printing.
Figure 6. Definitive hollow maxillary obturator. A, Polished surface. B, Tissue surface.
decreased esthetic properties as a result of saliva and water entering the hollow part. The 3D method could also ensure that the thickness of the denture mucosal side is homogeneous; however, there is a risk of the dentures being too thick because of the use of the remaining alveolar ridge as a reference for the polishing side. Therefore, a contraindication would be patients requiring a light-weight prosthesis. Limitations of the technique include the possibility of incomplete polymerization of the interfacial layers and the possibility of unpolymerized monomers remaining in the hollow center. Studies are needed to determine the biostability of prostheses created with this method and to refine the design and develop a method of easily fabricating an entire prosthesis along with a hollow obturator using 3D digital technologies.
REFERENCES
SUMMARY A method applying optical laminate molding techniques can be used to fabricate single-piece hollow prostheses with no joints. Using the optical laminate molding techniques is a time-efficient method that conserves the integrity of the fabrication process without the modeling and sealing processes of conventional methods. THE JOURNAL OF PROSTHETIC DENTISTRY
1. Keyf F. Obturator prostheses for hemi-maxillectomy patients. J Oral Rehabil 2001;28:821-9. 2. Wu Y, Schaaf NG. Comparison of weight reduction in different designs of solid and hollow obturator prostheses. J Prosthet Dent 1989;62:214-7. 3. McAndrew KS, Rothenberger S, Minsley GE. An innovative investment method for the fabrication of a closed hollow obturator prosthesis. J Prosthet Dent 1998;80:129-32. 4. Habib BH, Driscoll CF. Fabrication of a closed hollow obturator. J Prosthet Dent 2004;91:383-5. 5. Buzayan MM, Ariffin YT, Yunus N. Closed hollow bulb obturator one-step fabrication: a clinical report. J Prosthodont 2013;22:591-5. 6. Patil PG, Patil SP. Fabrication of a hollow obturator as a single unit for management of bilateral subtotal maxillectomy. J Prosthodont 2012;21:194-9. 7. Padmanabhan TV, Kumar VA, Mohamed KK, Unnikrishnan N. Prosthetic rehabilitation of a maxillectomy with a two-piece hollow bulb obturator. A clinical report. J Prosthodont 2011;20:394-401. 8. Hori K, Miyamoto T, Ono T, Yamamoto M, Shiroshita N, Maeda Y, et al. One step polymerizing technique for fabricating a hollow obturator. J Prosthodont Res 2013;57:294-7. 9. Kocacikli M, Yalug S, Yazicioglu H, Yilmaz C. Fabricating a hollow obturator with visible light-cured resin system. J Prosthodont 2008;17:596-8. 10. Van der Zande MM, Gorter RC, Aartman IH, Wismeijer D. Adoption and use of digital technologies among general dental practitioners in the Netherlands. PLoS One 2015;10:e0120725. 11. Bilgin MS, Baytaro glu EN, Erdem A, Dilber E. A review of computer-aided design/computer-aided manufacture techniques for removable denture fabrication. Eur J Dent 2016;10:286-91. 12. Marinello C. The digital revolution’s impact on prosthodontics. Int J Prosthodont 2015;29:431-3. 13. Schwindling FS, Stober T. A comparison of two digital techniques for the fabrication of complete removable dental prostheses: A pilot clinical study. J Prosthet Dent 2016;116:756-63. 14. Schweiger J, Guth JF, Edelhoff D, Stumbaum J. Virtual evaluation for CADCAM-fabricated complete dentures. J Prosthet Dent 2017;117:28-33. 15. Wimmer T, Gallus K, Eichberger M, Stawarczyk B. Complete denture fabrication supported by CAD/CAM. J Prosthet Dent 2016;116:541-6.
Koyama et al
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2019
16. Jiang FF, Hou Y, Lu L, Ding XX, Li W, Yan AH. Functional evaluation of a CAD/ CAM prosthesis for immediate defect repair after total maxillectomy: a case series of 18 patients with maxillary sinus cancer. J Esthet Restor Dent 2015;1:80-9. 17. Jiao T, Zhu C, Dong X, Gu X. Rehabilitation of maxillectomy defects with obturator prostheses fabricated using computer-aided design and rapid prototyping: a pilot study. Int J Prosthodont 2014;27:480-6. 18. Kim MS, Lee JY, Shin SW. Fabricating an obturator using rapid prototyping to design the framework: a case report. Int J Prosthodont 2014;27:439-41. 19. Rodney J, Chicchon I. Digital design and fabrication of surgical obturators based only on preoperative computed tomography data. Int J Prosthodont 2017;30:111-2. 20. Torabi K, Farjood E, Hamedanib S. Rapid prototyping technologies and their applications in prosthodontics, a review of literature. J Dent 2015;16:1-9. 21. Wu J, Li Y, Zhang Y. Use of intraoral scanning and 3-dimensional printing in the fabrication of a removable partial denture for a patient with limited mouth opening. J Am Dent Assoc 2017;148:338-41.
Koyama et al
5
Corresponding author: Dr Shigeto Koyama Tohoku University Hospital Maxillofacial Prosthetics Clinic 4-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi 980-8575 JAPAN Email: [email protected] Acknowledgments The authors thank Dr Kuniyuki Izumita and Dr Takehiko Mito for assistance in laboratory processing and data collection. The authors also thank Enago for English language editing services. Copyright © 2019 by the Editorial Council for The Journal of Prosthetic Dentistry. https://doi.org/10.1016/j.prosdent.2019.05.020
THE JOURNAL OF PROSTHETIC DENTISTRY