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Technique for fabricating a lightweight, urethane-lined silicone orbital prosthesis
Technique for fabricating a lightweight, urethane-lined silicone orbital prosthesis Sudarat Kiat-amnuay, DDS, MS,a James C. Lemon, DDS,b and Peggy J. Wesleyc The University of Texas M. D. Anderson Cancer Center, Houston, Texas A technique is presented for packing an acrylic resin core and controlling the thickness of an orbital prosthesis with the use of an irreversible hydrocolloid matrix. This technique provides a durable core without damaging the orbital prosthesis mold and permits a controllable thickness and therefore a lighter prosthesis. (J Prosthet Dent 2001;85:210-3.)
T
he success of any facial prosthesis depends on many factors, including the extent and location of the defect.1 Occasionally, extensive surgical procedures for advanced tumors of the facial region leave a large defect area, compromising the prosthetic retention caused by the weight of the final prosthesis. An acrylic resin core as part of a 3-piece mold has been used to control the thickness and weight of nasal prostheses.2,3 However, packing autopolymerizing acrylic resin in the mold of a large orbital prosthesis to lighten it may cause damage to the fine detail of the orbital area. This article presents a technique for packing an acrylic resin core and controlling the thickness of an orbital prosthesis with the use of an irreversible hydrocolloid matrix. It also discusses the use of an acrylic resin core in conjunction with the fabrication of a urethane-lined, silicone orbital prosthesis with magnet attachments to an acrylic resin framework. The technique presented has at least 3 advantages: First, it provides a durable core without damaging the orbital prosthesis mold; second, it permits a controllable minimal thickness and thus a lighter prosthesis; and third, it creates a smooth, easily cleanable urethane-lined surface for the prosthesis.
Fig. 1. Sculpted prosthesis sealed to lower half of mold.
PROCEDURE 1. Pour the upper half of the mold using improved stone over the sculpted prosthesis (Fig. 1) that has been sealed to the lower half of the mold. 2. After the stone has set, separate and thoroughly clean the molds (Fig. 2). 3. Apply separating medium (Vaseline; ChesebroughPond’s Inc, Sherwood Medical, St. Louis, Mo.)
Fig. 2. Upper and lower halves of orbital prosthesis mold.
aSenior
Fellow, Maxillofacial Prosthetics, Section of Oncologic Dentistry and Prosthodontics, M.D. Anderson Cancer Center; Adjunct Instructor, Department of Diagnostic Sciences, Restorative Dentistry, and Prosthodontics, University of Louisville, Louisville, Ky. bAssociate Professor, Section of Oncologic Dentistry and Prosthodontics. cAnaplastologist, Section of Oncologic Dentistry and Prosthodontics. 210 THE JOURNAL OF PROSTHETIC DENTISTRY
inside both molds. Mix the irreversible hydrocolloid impression material in a 1:3 powder-liquid ratio using a vacuum mixer. Place the impression material in both sides of the mold and close. When the material has set, separate the mold and trim the excess. VOLUME 86 NUMBER 2
KIAT-AMNUAY, LEMON, AND WESLEY
THE JOURNAL OF PROSTHETIC DENTISTRY
A Fig. 3. Modified irreversible hydrocolloid matrix with space for making acrylic resin core.
B Fig. 5. A, Matrix with acrylic resin trial packed inside molds; B, finished acrylic resin core with magnet access openings. Fig. 4. Irreversible hydrocolloid matrix with baseplate wax block-out on upper half of mold.
4. Check the thickness of the prosthesis. Use a blade to cut the area of the prosthesis that needs to be thin by leaving space for the acrylic resin core (Fig. 3). 5. Place the irreversible hydrocolloid matrix on the upper half of the mold. Adapt 2 uniform thicknesses of baseplate wax to the area inside the mold (Fig. 4). 6. In the lower mold, cut a Y groove to use as a key to orient the core in one position.2 7. Apply separating medium (tinfoil substitute, VitaSep, Fricke International, Inc, Villa Park, Ill.) to both molds. Mix autopolymerizing acrylic resin in a 3:1 powder-liquid ratio. At the dough stage, trial pack the acrylic resin in both sides of the mold and close. When the material has set, separate the molds (Fig. 5, A), trim the excess, finish, polish, and drill the magnet access opening (Fig. 5, B). 8. Repack the irreversible hydrocolloid matrix with AUGUST 2001
the acrylic resin core in place (Fig. 6, A). Check the trial thickness of the final prosthesis; mark and adjust the core until the desirable thickness is obtained (Fig. 6, B). 9. Fabricate a perforated duplicate cast for polyurethane lining4,5 by duplicating the lower half of the mold with the acrylic resin core in place (Fig. 7, A). 10. Coat the acrylic resin core with beeswax as a separating medium before packing the silicone. Reapply the tinfoil substitute to both molds. Pack the final prosthesis using a mixture of silicone elastomers (MDX4-4210 and Silastic medical adhesive type A, Dow Corning Corp, Midland, Mich.). The polyurethane lining in relation to the acrylic resin core during the silicone packing procedure is shown in Figure 7, B. After the prosthesis has been polymerized, remove it from the mold, and prepare it for delivery (Fig. 8). 211
THE JOURNAL OF PROSTHETIC DENTISTRY
A
B Fig. 6. A, Irreversible hydrocolloid matrix repacked with acrylic resin core in place; B, cross-section of matrix shows that desirable thickness has been obtained.
KIAT-AMNUAY, LEMON, AND WESLEY
A
B Fig. 7. A, Perforated duplicate cast for polyurethane lining; B, polyurethane lining in relation to acrylic resin core during silicone packing procedure.
DISCUSSION Irreversible hydrocolloid in a 1:3 powder-liquid ratio is preferred in this technique for the following reasons: (1) It is soft enough not to damage delicate areas of the mold during packing and removal of the matrix, (2) it flows easily and allows more working time, and (3) it is inexpensive and readily available. Silicone materials can also be used with this technique.3 By duplicating the lower half of the mold with the acrylic resin core in place, the urethane is laid over the core and thus lines all tissue surfaces of the prosthesis, except the areas in which the magnets are located (because the urethane has been cut to provide access for injection of the material). In contrast, if the acrylic resin core is not incorporated into the perforated duplicate cast, the polyurethane will be underneath the core. After the prosthesis has been polymerized, the urethane will have to be cut to remove the core. Consequently, some parts of the tissue side of the 212
prosthesis will not have the polyurethane lining, which may pose some retention and long-term hygiene problems for the prosthesis and patient.
SUMMARY The technique presented provides a lightweight, smooth, easily cleansable urethane-lined surface for an orbital prosthesis. REFERENCES 1. Finlay PM. Prosthodontics. In: Sautar DA, Tiwari R, editors. Excision and reconstruction in head and neck cancer. New York (NY): Churchill Livingstone; 1994. p. 113-6. 2. Lemon JC, Martin JW, Echeverri JC, King GE. An acrylic resin core for processing silicone facial prostheses. J Prosthet Dent 1992;67:374-6. 3. Lemon JC, Martin JW, Wesley PJ, King GE. Technique for controlling the thickness of a facial prosthesis when an acrylic resin core is used. J Prosthet Dent 1993;70:447-8. 4. Udagama A. Urethane-lined silicone facial prostheses. J Prosthet Dent 1987;58:351-4. 5. Lemon JC, Martin JW, King GE. Modified technique for preparing a polyurethane lining for facial prostheses. J Prosthet Dent 1992;67:228-9.
VOLUME 86 NUMBER 2
KIAT-AMNUAY, LEMON, AND WESLEY
THE JOURNAL OF PROSTHETIC DENTISTRY
Reprint requests to: DR JAMES C. LEMON SECTION OF DENTAL ONCOLOGY AND PROSTHODONTICS, BOX 441 THE UNIVERSITY OF TEXAS M. D. ANDERSON CANCER CENTER HOUSTON, TX 77030 FAX: (713)794-4662 E-MAIL: [email protected] Copyright © 2001 by The Editorial Council of The Journal of Prosthetic Dentistry. 0022-3913/2001/$35.00 + 0. 10/1/115876
doi:10.1067/mpr.2001.115876
A
B Fig. 8. A, Tissue side of final orbital prosthesis; B, final prosthesis.
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AUGUST 2001
213
T
he success of any facial prosthesis depends on many factors, including the extent and location of the defect.1 Occasionally, extensive surgical procedures for advanced tumors of the facial region leave a large defect area, compromising the prosthetic retention caused by the weight of the final prosthesis. An acrylic resin core as part of a 3-piece mold has been used to control the thickness and weight of nasal prostheses.2,3 However, packing autopolymerizing acrylic resin in the mold of a large orbital prosthesis to lighten it may cause damage to the fine detail of the orbital area. This article presents a technique for packing an acrylic resin core and controlling the thickness of an orbital prosthesis with the use of an irreversible hydrocolloid matrix. It also discusses the use of an acrylic resin core in conjunction with the fabrication of a urethane-lined, silicone orbital prosthesis with magnet attachments to an acrylic resin framework. The technique presented has at least 3 advantages: First, it provides a durable core without damaging the orbital prosthesis mold; second, it permits a controllable minimal thickness and thus a lighter prosthesis; and third, it creates a smooth, easily cleanable urethane-lined surface for the prosthesis.
Fig. 1. Sculpted prosthesis sealed to lower half of mold.
PROCEDURE 1. Pour the upper half of the mold using improved stone over the sculpted prosthesis (Fig. 1) that has been sealed to the lower half of the mold. 2. After the stone has set, separate and thoroughly clean the molds (Fig. 2). 3. Apply separating medium (Vaseline; ChesebroughPond’s Inc, Sherwood Medical, St. Louis, Mo.)
Fig. 2. Upper and lower halves of orbital prosthesis mold.
aSenior
Fellow, Maxillofacial Prosthetics, Section of Oncologic Dentistry and Prosthodontics, M.D. Anderson Cancer Center; Adjunct Instructor, Department of Diagnostic Sciences, Restorative Dentistry, and Prosthodontics, University of Louisville, Louisville, Ky. bAssociate Professor, Section of Oncologic Dentistry and Prosthodontics. cAnaplastologist, Section of Oncologic Dentistry and Prosthodontics. 210 THE JOURNAL OF PROSTHETIC DENTISTRY
inside both molds. Mix the irreversible hydrocolloid impression material in a 1:3 powder-liquid ratio using a vacuum mixer. Place the impression material in both sides of the mold and close. When the material has set, separate the mold and trim the excess. VOLUME 86 NUMBER 2
KIAT-AMNUAY, LEMON, AND WESLEY
THE JOURNAL OF PROSTHETIC DENTISTRY
A Fig. 3. Modified irreversible hydrocolloid matrix with space for making acrylic resin core.
B Fig. 5. A, Matrix with acrylic resin trial packed inside molds; B, finished acrylic resin core with magnet access openings. Fig. 4. Irreversible hydrocolloid matrix with baseplate wax block-out on upper half of mold.
4. Check the thickness of the prosthesis. Use a blade to cut the area of the prosthesis that needs to be thin by leaving space for the acrylic resin core (Fig. 3). 5. Place the irreversible hydrocolloid matrix on the upper half of the mold. Adapt 2 uniform thicknesses of baseplate wax to the area inside the mold (Fig. 4). 6. In the lower mold, cut a Y groove to use as a key to orient the core in one position.2 7. Apply separating medium (tinfoil substitute, VitaSep, Fricke International, Inc, Villa Park, Ill.) to both molds. Mix autopolymerizing acrylic resin in a 3:1 powder-liquid ratio. At the dough stage, trial pack the acrylic resin in both sides of the mold and close. When the material has set, separate the molds (Fig. 5, A), trim the excess, finish, polish, and drill the magnet access opening (Fig. 5, B). 8. Repack the irreversible hydrocolloid matrix with AUGUST 2001
the acrylic resin core in place (Fig. 6, A). Check the trial thickness of the final prosthesis; mark and adjust the core until the desirable thickness is obtained (Fig. 6, B). 9. Fabricate a perforated duplicate cast for polyurethane lining4,5 by duplicating the lower half of the mold with the acrylic resin core in place (Fig. 7, A). 10. Coat the acrylic resin core with beeswax as a separating medium before packing the silicone. Reapply the tinfoil substitute to both molds. Pack the final prosthesis using a mixture of silicone elastomers (MDX4-4210 and Silastic medical adhesive type A, Dow Corning Corp, Midland, Mich.). The polyurethane lining in relation to the acrylic resin core during the silicone packing procedure is shown in Figure 7, B. After the prosthesis has been polymerized, remove it from the mold, and prepare it for delivery (Fig. 8). 211
THE JOURNAL OF PROSTHETIC DENTISTRY
A
B Fig. 6. A, Irreversible hydrocolloid matrix repacked with acrylic resin core in place; B, cross-section of matrix shows that desirable thickness has been obtained.
KIAT-AMNUAY, LEMON, AND WESLEY
A
B Fig. 7. A, Perforated duplicate cast for polyurethane lining; B, polyurethane lining in relation to acrylic resin core during silicone packing procedure.
DISCUSSION Irreversible hydrocolloid in a 1:3 powder-liquid ratio is preferred in this technique for the following reasons: (1) It is soft enough not to damage delicate areas of the mold during packing and removal of the matrix, (2) it flows easily and allows more working time, and (3) it is inexpensive and readily available. Silicone materials can also be used with this technique.3 By duplicating the lower half of the mold with the acrylic resin core in place, the urethane is laid over the core and thus lines all tissue surfaces of the prosthesis, except the areas in which the magnets are located (because the urethane has been cut to provide access for injection of the material). In contrast, if the acrylic resin core is not incorporated into the perforated duplicate cast, the polyurethane will be underneath the core. After the prosthesis has been polymerized, the urethane will have to be cut to remove the core. Consequently, some parts of the tissue side of the 212
prosthesis will not have the polyurethane lining, which may pose some retention and long-term hygiene problems for the prosthesis and patient.
SUMMARY The technique presented provides a lightweight, smooth, easily cleansable urethane-lined surface for an orbital prosthesis. REFERENCES 1. Finlay PM. Prosthodontics. In: Sautar DA, Tiwari R, editors. Excision and reconstruction in head and neck cancer. New York (NY): Churchill Livingstone; 1994. p. 113-6. 2. Lemon JC, Martin JW, Echeverri JC, King GE. An acrylic resin core for processing silicone facial prostheses. J Prosthet Dent 1992;67:374-6. 3. Lemon JC, Martin JW, Wesley PJ, King GE. Technique for controlling the thickness of a facial prosthesis when an acrylic resin core is used. J Prosthet Dent 1993;70:447-8. 4. Udagama A. Urethane-lined silicone facial prostheses. J Prosthet Dent 1987;58:351-4. 5. Lemon JC, Martin JW, King GE. Modified technique for preparing a polyurethane lining for facial prostheses. J Prosthet Dent 1992;67:228-9.
VOLUME 86 NUMBER 2
KIAT-AMNUAY, LEMON, AND WESLEY
THE JOURNAL OF PROSTHETIC DENTISTRY
Reprint requests to: DR JAMES C. LEMON SECTION OF DENTAL ONCOLOGY AND PROSTHODONTICS, BOX 441 THE UNIVERSITY OF TEXAS M. D. ANDERSON CANCER CENTER HOUSTON, TX 77030 FAX: (713)794-4662 E-MAIL: [email protected] Copyright © 2001 by The Editorial Council of The Journal of Prosthetic Dentistry. 0022-3913/2001/$35.00 + 0. 10/1/115876
doi:10.1067/mpr.2001.115876
A
B Fig. 8. A, Tissue side of final orbital prosthesis; B, final prosthesis.
Receive Table of Contents by E-mail To receive the table of contents by e-mail, sign up through our Web site at http://www.mosby.com/prosdent Choose E-mail Notification. Simply type your e-mail address in the box and click the Subscribe button. Alternatively, you may send an e-mail message to [email protected]. Leave the subject line blank and type the following as the body of your message: subscribe prosdent_toc You will receive an e-mail to confirm that you have been added to the mailing list. Note that table of contents e-mails will be sent out when a new issue is posted to the Web site.
AUGUST 2001
213