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Mold Oor


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  • 1. CAD/CAM ear model and virtual construction of the mold Leonardo Ciocca, DDS, PhD,a Roberto Mingucci, PhD,b Gianfranco Gassino, MD, DMD,c and Roberto Scotti, MD, DMDd Alma Mater Studiorum University of Bologna, Bologna, Italy; University of Turin, Turin, Italy This article describes a technique to make an implant-retained maxillofacial prosthesis using CAD/CAM technology and a rapid prototyping machine. The primary advantage of this technique is virtual 3-dimensional integration of the defective surface with the mirrored and digitalized normal ear. Making an impression of the defective side is not neces- sary, because only the position of the implants must be recorded to develop the bar for the retention of the prosthesis. This procedure allows positioning of the ear straight onto the computer screen, eliminating the diagnostic waxing, and the fabrication of the stone mold is not necessary because of the rapid prototyping process. (J Prosthet Dent 2007;98:339-343) In a previous article,1 the authors agement is the base of the external (other than the one used for fabrica- describe a technique using rapid pro- ear, which must fit perfectly onto the tion of the implant bar), trial waxing totyping to fabricate a mirrored vol- defective side. To achieve this goal, the for the positioning of the ear, and the ume of healthy ear for situations that wax pattern is developed and adapt- indirect fabrication of the stone mold. necessitate ablative surgery of the ex- ed to the stone cast, but this makes This technique is useful both for con- ternal ear. A recent report by Mardini it difficult to preserve the correct po- ventional mold fabrication (eliminat- et al2 described a technique to obtain sition as previously determined on ing only the trial waxing), and for the a further simplification of the mirror- the skin of the patient. The protocol completely automated method of image wax pattern of an ear for the presented in this article describes a mold fabrication. The primary ad- fabrication of an auricular prosthe- method of projecting the position of vantages of this technique include sis using rapid prototyping technol- the new ear directly onto the personal allowing scanning of the existing ear ogy involving computer-aided design computer (PC) screen and developing without making an impression, elimi- and computer-aided manufacturing a wax pattern that can be transferred nation of the diagnostic waxing of the (CAD/CAM). A review of the litera- into the mold for silicone processing. lost ear for positioning onto the skin, ture identified several reports describ- As an alternative procedure, this pro- in relation to the skull of the patient ing the manufacture of an ear pros- tocol also allows for fabrication of and the implants, and creation of the thesis.3-16 Laser-scanning techniques the mold. Using the negative volume mold directly from the volume of the and CAD/CAM systems have been of the scanned and mirrored healthy mirrored ear. The disadvantages of used to design and develop auricular ear, and virtually adapting it to the this procedure are the technical skills prostheses.17-18 scanned defective side surface, this necessary to use CAD/CAM equip- However, the remaining problem protocol eliminates the need to make ment and the related costs of the lab- to be solved in terms of virtual man- an impression of the defective side oratory equipment required to cre- Presented at the International Society of Maxillofacial Rehabilitation/American Academy of Maxillofacial Prosthetics joint meeting, Maui, Hawaii, October 2006. a Assistant Clinical Professor of Maxillofacial Prosthetics, Section of Oral and Maxillofacial Rehabilitation, Department of Oral Sci- ence, Alma Mater Studiorum University of Bologna. b Professor and Dean, Department of Architecture and Urban Planning, Faculty of Engineering, Alma Mater Studiorum University of Bologna. c Associate Professor, Section of Oral and Maxillofacial Implant Rehabilitation, University of Turin. d Dean and Professor of Prosthodontics, Section of Oral and Maxillofacial Rehabilitation, Department of Oral Science, Alma Mater Studiorum University of Bologna. Ciocca et al
  • 2. 340 Volume 98 Issue 5 ate the 3-dimensional (3-D) model, points, each one with 3-D point co- a transfer impression (Permadyne Ga- including the 3-D scanner and rapid ordinates. rant 2:1, 3M ESPE, Seefeld, Germany) prototyping machine. 8. Elaborate these digitalized ear of the craniofacial implants. Then surfaces using software (Rapidform send the cast to the laboratory for TECHNIQUE CAD, version 2006; INUS Technology, fabrication of the bar. Fabricate the Inc, Seoul, Korea) to recombine, align, bar with at least a 1.5-mm distance 1. Place at least two 3-mm cranio- and blend the different surfaces into between the skin and the bar and a facial implants (Vista Fix; Cochlear a single virtual model, eliminating the maximum cantilever length of 8 mm. Americas, Englewood, Colo) in the surface abnormalities, remeshing the 11. Use a skin adhesive (Blom- mastoid bone and wait for 3 to 4 organization of the triangulated mesh Singer Brush-on Silicone Skin Adhe- months prior to the stage II surgical of points, and filling in the surface sive; InHealth Technologies) to adhere exposure procedure. gaps that remain after data elabora- the same small spherical balls onto 2. Use a laser scanner (Minolta tion. the skin around the defect (Fig. 1). VIVID 900; Minolta Co, Osaka, Ja- 9. To merge the 3-D point clouds, 12. Connect the bar to the im- pan) connected to a personal com- locate the same 3-D points in each plants so that it can be scanned to- puter (Asus, Pentium 4 - 2.8; ASUS- digital image and overlap the center gether with the skin of the defective TeK Computer Inc, Taipei, Taiwan) to of each colored spherical pin with side. Then, develop the acrylic resin acquire the 3-D spatial coordinates of the corresponding one in the other substructure that will be included in the healthy ear with software (Polygon angled image scans and integrate all the silicone prosthesis to retain the Editing Tool, version 1.03; Minolta measurements. bar clips used to connect the pros- Co). Make the first measurement af- 10. On the defect side, manufac- thesis to the bar, using a CAD/CAM ter positioning the patient in front of ture the metal bar (Cendres & Metaux design. the laser scanner. SA, Biel/Bienne, Switzerland) to be 13. Repeat steps 2 through 8 of this 3. Randomly position at least supported by implants prior to laser protocol on the skin of the patient to three 2.5-mm-diameter colored balls scanning the tissue surface. First make obtain a virtual 3-D image of the de- (Ballpin; Gruppo Buffetti SpA, Milan, Italy) onto the healthy ear using a skin adhesive (Blom-Singer Brush-on Sili- cone Skin Adhesive; InHealth Tech- nologies, Carpinteria, Calif ). Record the volume of the external healthy ear straight onto the skin of the patient (without making an impression) with the laser scanner (Minolta VIVID 900; Minolta Co). 4. As an alternative to step 2, use a stone cast of the healthy ear instead. Develop a stone cast of the healthy ear using conventional techniques.3 Randomly position the cast of the ex- 1 Pin system on defective side. isting ear on a platform with colored pins (Ballpin; Gruppo Buffetti SpA) (diameter of 2.5 mm) around it, as described by Ciocca et al.1 5. Place the patient in 4 random positions and make 4 laser measure- ments of the surface from different angles to detect all undercuts. 6. Record these patterns with the laser scanner software (Polygon Edit- ing Tool, version 1.03; Minolta Co). 7. Represent the surface of the scanned healthy ear with 4 clouds (the entire number of the 3-D points rep- resenting a volume surface) of 50,000 2 Digitalized image after laser scan of skin. The Journal of Prosthetic Dentistry Ciocca et al
  • 3. November 2007 341 fective side (Fig. 2), and develop the determine the correct position in re- 17. Virtually design, on the PC, the final STL file of the defective side. lation to the face of the patient (Fig. acrylic resin substructure in relation 14. Mirror the 3-D image of the 3). to the bar dimensions and the mir- healthy ear to create a pattern of the 16. Once the STL file of the exter- rored ear thickness, to obtain a sepa- lost ear. nal ear has been developed, represent rate structure from the entire prosthe- 15. Using CAD elaboration, su- it as a negative volume and transform sis. Prototype the resin substructure perimpose the two 3-D images of the this pattern into a new STL file for the alone (not connected with the base healthy ear and the defective side, and mold design (Fig. 4). of the mold) and position it into the 3 Integration of external mirrored ear with laser-scanned 4 Virtual mold. skin of defective side. A B C D 5 CAD/CAM fabrication of substructure. A, Laser-scanned bar and defective side. B, Computer-assisted design of substructure. C, CAD of mold with separate substructure. D, CAM of mold: substructure is separate and perfectly positioned onto prototyped bar in mold. Ciocca et al
  • 4. 342 Volume 98 Issue 5 mold before silicone processing using the scanned bar on implants in the base of the defective side (Fig. 5). 18. Process the STL file using the computer system (Z Printer 310; Z Corp, Burlington, Mass) to manu- facture the mold in a single step. Us- ing the computer system and layers of sealant (Z Corp Sealant; Z Corp) with layers of resin powder (Z Corp Powder; Z Corp), develop the entire volume of the mold through layer-by- layer manufacturing. 19. Allow 60 minutes for the acryl- ic resin to polymerize. 20. Extract the cast from the pow- der and then coat the surface of the cast with the epoxy resin (Renlam M- 1; Fuchs SpA, San Giuliano Milanese, Italy) to further harden the mold. A 21. To correctly position the acryl- ic resin substructure in the final mold, use as a positional landmark the pro- totyped bar previously scanned on the defective side (see step 12) (Fig. 5, D). Do this in the same manner as for a conventional stone mold, for which the resin substructure is positioned onto the metal bar before process- ing the silicone. Insert the connect- ing structure onto the prototyped bar, to precisely place it onto the 3-D mold base (Fig. 6, A). Adhere it with B an adhesive (496; Loctite Italia SpA, 6 A, Cast with processed silicone. B, Bar retainers. Brugherio, Italy). 22. Complete conventional sili- cone (VST-30; Factor II, Lakeside, Ariz) processing procedures3 to ob- tain the definitive prosthesis, as for a conventional stone mold processing (Fig. 6, B). 23. Use a spectrophotometer to determine the intrinsic color of the ear (SpectroShade Office; MHT SpA, Verona, Italy). 24. Apply extrinsic colors (Extrin- sic; Factor II Inc) and use silicone adhesive (A-564; Factor II Inc) as a sealant. Finally, apply the matting dis- persion liquid (MD-564; Factor II Inc) 7 Definitive prosthesis. mixed with the silicone dispersion liq- uid (TS-564; Factor II Inc) to provide a matte appearance to the prosthesis (Fig. 7). The Journal of Prosthetic Dentistry Ciocca et al
  • 5. November 2007 343 DISCUSSION for example, in malformations such as Runte B, Meyer U, et al. Optical data acqui- sition for computer-assisted design of facial Treacher-Collins syndrome, or when prostheses. Int J Prosthodont 2002;15:129- This article describes the protocol an impression of the nose was not 32. that is currently used by the authors made before surgery. Further studies 9. Reitemeier B, Notni G, Heinze M, Schone C, Schmidt A, Fichtner D. Optical mod- to make facial prostheses at the Sec- are necessary to develop a protocol to eling of extraoral defects. J Prosthet Dent tion of Prosthodontics, Department produce the silicone definitive pros- 2004;91:80-4. of Oral Sciences, University of Bolo- thesis with the 3-D printer. 10.Nusinov NS, Gay WD. A method for obtaining the reverse image of an ear. J gna, Italy. Although the cost of the Prosthet Dent 1980;44:68-71. equipment for this procedure may SUMMARY 11.Mankovich NJ, Curtis DA, Kagawa T, Beu- mer J 3rd. Comparison of computer-based seem high, several rapid prototyp- fabrication of alloplastic cranial implants ing machines and simple laser scan- The procedure presented in this with conventional techniques. J Prosthet ners are currently available at a lower article describes a technique to make Dent 1986;55:606-9. a maxillofacial prosthesis using CAD/ 12.Lemon JC, Okay DJ, Powers JM, Martin JW, cost than those presented in this ar- Chambers MS. Facial moulage: the effect ticle. The conventional, average fee CAM technology and a rapid proto- of a retarder on compressive strength and in Italy for the artistic waxing of the typing machine. Making an impres- working and setting times of irreversible hydrocolloid impression material. J Prosthet prosthesis is 700 USD, and 310 USD sion of the healthy and defective side Dent 2003;90:276-81. for the manufacturing of the acrylic is not necessary, because this protocol 13.Kubon TM, Anderson JD. An implant-re- resin substructure by the dental tech- allows scanning and positioning of tained auricular impression technique to minimize soft tissue distortion. J Prosthet nician. Using an external rapid proto- the lost ear directly onto the comput- Dent 2003;89:97-101. typing service, a laser scanner, which er screen, eliminating the diagnostic 14.Cheah CM, Chua CK, Tan KH, Teo CK. currently costs 2400 USD, is needed. waxing. Moreover, preparation of the Integration of laser surface digitizing with CAD/CAM techniques for developing facial For each prosthesis, the fees for rapid stone mold is not necessary, because prosthesis. Part 1: Design and fabrication prototyping are not greater than 70 of the rapid prototyping process. of prosthesis replicas. Int J Prosthodont USD, and CAD elaboration costs ap- 2003;16:435-41. 15.Cheah CM, Chua CK, Tan KH, Teo CK. proximately 80 USD. The costs are REFERENCES Integration of laser surface digitizing with minimized if one has access to the CAD/CAM techniques for developing facial 1. Ciocca L, Scotti R. CAD-CAM generated prosthesis. Part 2: Development of molding CAD/CAM system. Then the only cost ear cast by means of a laser scanner and techniques for casting prosthetic parts. Int J is that of the powder and acrylic resin rapid prototyping machine. J Prosthet Dent Prosthodont 2003;16:543-8. for the rapid prototyping machine 2004;92:591-5. 16.Taylor TD. Clinical maxillofacial prosthetics. 2. Al Mardini M, Ercoli C, Grasser GN. A Chicago: Quintessence; 2000. p. 245-64. (15 USD). technique to produce a mirror-image wax 17.Jiao T, Zhang F, Huang X, Wang C. Design Using this protocol, the patients pattern of an ear using rapid prototyping and fabrication of auricular prostheses are scheduled for only 3 appoint- technology. J Prosthet Dent 2005;94:195-8. by CAD/CAM system. Int J Prosthodont 3. Beumer J, Curtis TA, Marunick MT. Maxillo- 2004;17:460-3. ments. The first appointment is for facial rehabilitation: prosthetic and surgical 18.Coward TJ, Scott BJ, Watson RM, Richards impressing implants, and the second consideration. St. Louis: Elsevier; 1996. p. R. A comparison between computerized is for the trial insertion of the bar and 377-453. tomography, magnetic resonance imaging, 4. Hecker DM. Maxillofacial rehabilitation of and laser scanning for capturing 3-dimen- the laser scanning of the skin. A third a large facial defect resulting from an arter- sional data from a natural ear to aid reha- appointment is needed for trial inser- ovenous malformation utilizing a two-piece bilitation. Int J Prosthod 2006;19:92-100. tion of the prosthesis and for final ex- prosthesis. J Prosthet Dent 2003;89:109- 13. ternal coloring. 5. Girod S, Keeve E, Girod B. Advances in Corresponding author: If the surgery for the ear, nose, or interactive craniofacial surgery planning by Dr Leonardo Ciocca oculo-facial tumor removal can be 3D simulation and visualization. Int J Oral Department of Prosthodontics Maxillofac Surg 1995;24:120-5. Via S. Vitale, 59 scheduled after the prosthodontist 6. Coward TJ, Watson RM, Wilkinson IC. 40126 Bologna has had the opportunity to make an Fabrication of a wax ear by rapid-process ITALY modeling using stereolithography. Int J Fax: 0039-051-225208 impression of the facial structure to Prosthodont 1999;12:20-7. E-mail: be removed, the prosthesis design 7. Penkner K, Santler G, Mayer W, Pierer G, may be simplified. However, the au- Lorenzoni M. Fabricating auricular pros- Contributing author: thesis using three-dimensional soft tissue Giovanni Bacci, Computer Technician, SILAB thors have a virtual ear-nose library model itself. J Prosthet Dent 1999;82:482- Laboratory, Faculty of Engineering, Alma in their department, to facilitate the 4. Mater Studiorum University of Bologna. design when no healthy ear is present, 8. Runte C, Dirksen D, Delere H, Thomas C, Copyright © 2007 by the Editorial Council for The Journal of Prosthetic Dentistry. Ciocca et al