DRISCOLL,
15. Powers W, Kinzie J, Demidecki A, Bradfield J, Feldman A. A new system of field shaping for external beam radiation therapy. Radiology 1973;108:407-11, 16. Watkins D. A proposed method for making reduced wax compensators for use with high energy radiation beams. Br J Radio1 1975;48:760-2. 17. Weeks K, Fraass B, Hutchins K. Gypsum mixtures for compensator construction. Med Phys 1988$5:410-4. 18. Ellis F, Hall E, Oliver R. A compensator for variations in tissue thickness for high energy beams. Br J Radio1 1959,32:421-2. 19. Fletcher G. Textbook of radiotherapy. 3rd ed. Philadelphia:Lea & Febiger, 1980:20-4. 20. Ellis F. Accuracy in compensation for tissue heterogeneity in treatment by x-rays, supervoltage x-rays, and electron beams. Br J Radial 1960;33:404-5.
An acrylic
resin
TAYLOR,
AND
OSTROWSKI
21. Hall E, Oliver R. The use of metal compensators to correct for tissue heterogeneity in radiotherapy with high energy radiation beams. Br J Radio1 1962;35:852-5. 22. DeVita V, Hellman S, Rosenberg S. AIDS etiology, diagnosis, treatment, and prevention. 2nd ed. Philadelphia:JB Lippincott, 1988254-5.
Reprint
requests
to:
DR. CARL F. DRISCOLL C, MAXILLOFACIAI, PROSTHODONTICS USA DENTAC TRIPLER ARMY MEDICAL CENTER HONOLULU, HI 96859
core for processing
silicone
facial
prostheses
James C. Lemon, DDS,a Jack W. Martin, DDS, MS,b Juan C. Echeverri, DDS,C and Gordon E. King, DDSd The University of Texas, M.D. Anderson Cancer Center, Houston, Texas A technique is presented for making an acrylic resin core for processing silicone facial prostheses. This technique ensures a durable core that can be used to make multiple prostheses. The core resists fungal growth during storage and creates a smooth, easily cleanable internal surface for a facial prosthesis. The core also permits a controllable thickness and therefore a lighter prosthesis. (J PROSTHET DENT 1992;67:3’74-6.)
A
aAssistant Professor, Department of Dental Oncology. “Associate Professor, Department of Dental Oncology. CFellow, Department of Dental Oncology. dProfessor, Department of Dental Oncology. 10/l/29119
removable stone core, as part of a three-piece mold (Fig. l), hasoften been usedduring processingnasal prosthesesto control thickness and weight of the prostheses.Stone coresare susceptibleto abrasion and breakage. Continuous useof a stone core for multiple prosthesescan
Fig. 1. Three-piece mold with conventional stone core. Note fracture lines and repaired areasof core.
Fig. 2. Prosthesisprocessedwith stone core. Note rough internal silicone finish.
374
MARCH
1992
VOLUME
67
NUMBER
3
ACRYLIC
RESIN
CORE
FOR
FACIAL
PROSTHESES
3. Counter half (left) with wax spacer and tissue half (right) with blockout of undercuts (pointer) ready for packing of acrylic resin core. Fig.
Fig. 5. Opening of acrylic resin core allowing accessto magnets. Pointers show superior magnet and relief for magnet under left ala.
TECHNIQUE
Fig. 4. One-key designplacedin tissuehalf (pointer) will seat core in one direction only.
that
causeabrasion of the core surface, which can produce a rough inner surface of the prosthesis (Fig. 2). This rough internal surface of a nasal prosthesisis a hygiene problem and enhancesfungal growth.ll 2 A technique is presented for fabricating an autopolymerizing acrylic resin core to be placed into the center of a gypsummold for a facial prosthesis.The acrylic resincore offers advantagesover the commonly usedstone core that include (1) easeof fabrication; (2) durability; (3) easeof removal of the core; (4) smooth internal surface of the prosthesis that promotes better hygiene; (5) easier contouring of the prosthesisaround the core for placement of magnets;(6) resistanceto deterioration during microwave processing; and (7) resistance to fungal growth during storage of the mold.
THE
JOURNAL
OF PROSTHETIC
DENTISTRY
The two halves of the mold will be referred to as the counter half and the tissuehalf. The tissuehalf of the flask representsthe tissuesurface,while the counter half represent the prosthesisportion. 1. After the prosthesisis sculpted on the tissuehalf of the mold, pour the counter half in either improved or yellow stone. Improved stone may be used if no flask is usedto support the mold. Yellow stone may be usedif a polyvinyl chloride (PVC), metal- or fiber-basedflask is usedto support the mold.” 2. After the counter half has set, carefully separate the two halves. Remove the sculpting material and thoroughly clean the halves. 3. Adapt two thicknessesof baseplatewax to the insideof the counter half (Fig. 3). Maintain a uniform thickness of wax so that no thin surfacesare produced. 4. In the tissue half of the flask, develop a key that will orient the core in one position (Fig. 4). 5. Block out all undercuts in the tissuehalf of the mold in the area where the acrylic resin core will be located (Fig. 3) and apply separating medium (tinfoil substitute) to both halves of the mold. 6. Mix autopolymerizing acrylic resin in a 1:3 liquid-
375
LEMON
ET AL
8. After the material has cured, separatethe two halves and remove the core. Placement of the mold in warm water may facilitate removal of the core from the counter half. Both halves of the mold are then cleaned thoroughly. 9. Place the core in its key in the tissue side of the flask to ensureits proper position. If magnetsare to be incorporated into a tissue framework, the acrylic resin core can be opened (Figs. 5 and 6) to facilitate placement in the final prosthesis. 10. Polish the core to ensure a smooth surface prior to packing. Care should be taken that the keyed surface of the core is not altered. 11. Pack the prosthesis using the silicone material of choice and process it using standard methods or microwave techniques.4 12. After processing,the flask is carefully opened,the core and prosthesisare removed, and the prosthesisis prepared for delivery (Fig. 7). Fig. 6. Three-piece mold with acrylic resin core and finished prosthesis. Note core shows relief areas for three magnets (i.e., superior and both lateral alae).
SUMMARY A technique has been presented describingthe fabrication of an acrylic resin core for a silicone nasalprosthesis. This technique ensuresa durable core that can be usedrepeatedly. The coreresistsfungal growth during storageand provides a smooth,easily cleanableinternal surfacefor the prosthesis. It is also compatible with several microwave curing techniques.* Such acrylic resin cores may also be used as the third mold element in other siliconefacial prosthesismoldswhen it is desirableto keep the prosthesisthin and light. REFERENCES 1. Udagama DENT
Fig. 7. Internal surface of prosthesis processed with acrylic resin core. Note smooth internal surface (pointer).
powderratio and, whenthe resin isin the doughy stage, place it in both sidesof the mold. 7. Place polyethylene sheetsbetween the two halves of the mold and trial pack one or two times prior to removing the polyethylene sheetsand closingthe flask.
376
A. Urethane-lined
silicone
facial prostheses.
J PROSTHET
1987;58:351-4.
2. Veres EM, Wolfaardt JF, Becker PJ. An evaluation of the surface characteristics of a facial prosthetic elastomer. Part I. Review of the literature on the surface characteristics of dental materials with maxillofacial prosthetic application. J PROSTHET DENT 1990;63:193-7. 3. DeClerck JP. Microwave polymerization of acrylic resins used in dental prostheses. J PROSTHET DENT 1987;57:650-8. 4. Seals RR Jr, Cortes AL, Funk JL, Pare1 SM. Microwave techniques for fabrication of provisional facial prostheses. J PHOSTHET DENT 1989; 62:327-31. Reprint requests to: DR. JAMES C. LEMON DEPARTMENT OF DENTAL ONCOLOGY, Box 9 UNIVEWTY OF TEXAS, M. D. ANDERSON CANCER 1515 HOLCOMBE BLVD. HOUSTON, TX 77030
*Pagan
WJ. Personal
communication,
MARCH
CENTER
1990.
1992
VOLUME
67
NUMBER
3
15. Powers W, Kinzie J, Demidecki A, Bradfield J, Feldman A. A new system of field shaping for external beam radiation therapy. Radiology 1973;108:407-11, 16. Watkins D. A proposed method for making reduced wax compensators for use with high energy radiation beams. Br J Radio1 1975;48:760-2. 17. Weeks K, Fraass B, Hutchins K. Gypsum mixtures for compensator construction. Med Phys 1988$5:410-4. 18. Ellis F, Hall E, Oliver R. A compensator for variations in tissue thickness for high energy beams. Br J Radio1 1959,32:421-2. 19. Fletcher G. Textbook of radiotherapy. 3rd ed. Philadelphia:Lea & Febiger, 1980:20-4. 20. Ellis F. Accuracy in compensation for tissue heterogeneity in treatment by x-rays, supervoltage x-rays, and electron beams. Br J Radial 1960;33:404-5.
An acrylic
resin
TAYLOR,
AND
OSTROWSKI
21. Hall E, Oliver R. The use of metal compensators to correct for tissue heterogeneity in radiotherapy with high energy radiation beams. Br J Radio1 1962;35:852-5. 22. DeVita V, Hellman S, Rosenberg S. AIDS etiology, diagnosis, treatment, and prevention. 2nd ed. Philadelphia:JB Lippincott, 1988254-5.
Reprint
requests
to:
DR. CARL F. DRISCOLL C, MAXILLOFACIAI, PROSTHODONTICS USA DENTAC TRIPLER ARMY MEDICAL CENTER HONOLULU, HI 96859
core for processing
silicone
facial
prostheses
James C. Lemon, DDS,a Jack W. Martin, DDS, MS,b Juan C. Echeverri, DDS,C and Gordon E. King, DDSd The University of Texas, M.D. Anderson Cancer Center, Houston, Texas A technique is presented for making an acrylic resin core for processing silicone facial prostheses. This technique ensures a durable core that can be used to make multiple prostheses. The core resists fungal growth during storage and creates a smooth, easily cleanable internal surface for a facial prosthesis. The core also permits a controllable thickness and therefore a lighter prosthesis. (J PROSTHET DENT 1992;67:3’74-6.)
A
aAssistant Professor, Department of Dental Oncology. “Associate Professor, Department of Dental Oncology. CFellow, Department of Dental Oncology. dProfessor, Department of Dental Oncology. 10/l/29119
removable stone core, as part of a three-piece mold (Fig. l), hasoften been usedduring processingnasal prosthesesto control thickness and weight of the prostheses.Stone coresare susceptibleto abrasion and breakage. Continuous useof a stone core for multiple prosthesescan
Fig. 1. Three-piece mold with conventional stone core. Note fracture lines and repaired areasof core.
Fig. 2. Prosthesisprocessedwith stone core. Note rough internal silicone finish.
374
MARCH
1992
VOLUME
67
NUMBER
3
ACRYLIC
RESIN
CORE
FOR
FACIAL
PROSTHESES
3. Counter half (left) with wax spacer and tissue half (right) with blockout of undercuts (pointer) ready for packing of acrylic resin core. Fig.
Fig. 5. Opening of acrylic resin core allowing accessto magnets. Pointers show superior magnet and relief for magnet under left ala.
TECHNIQUE
Fig. 4. One-key designplacedin tissuehalf (pointer) will seat core in one direction only.
that
causeabrasion of the core surface, which can produce a rough inner surface of the prosthesis (Fig. 2). This rough internal surface of a nasal prosthesisis a hygiene problem and enhancesfungal growth.ll 2 A technique is presented for fabricating an autopolymerizing acrylic resin core to be placed into the center of a gypsummold for a facial prosthesis.The acrylic resincore offers advantagesover the commonly usedstone core that include (1) easeof fabrication; (2) durability; (3) easeof removal of the core; (4) smooth internal surface of the prosthesis that promotes better hygiene; (5) easier contouring of the prosthesisaround the core for placement of magnets;(6) resistanceto deterioration during microwave processing; and (7) resistance to fungal growth during storage of the mold.
THE
JOURNAL
OF PROSTHETIC
DENTISTRY
The two halves of the mold will be referred to as the counter half and the tissuehalf. The tissuehalf of the flask representsthe tissuesurface,while the counter half represent the prosthesisportion. 1. After the prosthesisis sculpted on the tissuehalf of the mold, pour the counter half in either improved or yellow stone. Improved stone may be used if no flask is usedto support the mold. Yellow stone may be usedif a polyvinyl chloride (PVC), metal- or fiber-basedflask is usedto support the mold.” 2. After the counter half has set, carefully separate the two halves. Remove the sculpting material and thoroughly clean the halves. 3. Adapt two thicknessesof baseplatewax to the insideof the counter half (Fig. 3). Maintain a uniform thickness of wax so that no thin surfacesare produced. 4. In the tissue half of the flask, develop a key that will orient the core in one position (Fig. 4). 5. Block out all undercuts in the tissuehalf of the mold in the area where the acrylic resin core will be located (Fig. 3) and apply separating medium (tinfoil substitute) to both halves of the mold. 6. Mix autopolymerizing acrylic resin in a 1:3 liquid-
375
LEMON
ET AL
8. After the material has cured, separatethe two halves and remove the core. Placement of the mold in warm water may facilitate removal of the core from the counter half. Both halves of the mold are then cleaned thoroughly. 9. Place the core in its key in the tissue side of the flask to ensureits proper position. If magnetsare to be incorporated into a tissue framework, the acrylic resin core can be opened (Figs. 5 and 6) to facilitate placement in the final prosthesis. 10. Polish the core to ensure a smooth surface prior to packing. Care should be taken that the keyed surface of the core is not altered. 11. Pack the prosthesis using the silicone material of choice and process it using standard methods or microwave techniques.4 12. After processing,the flask is carefully opened,the core and prosthesisare removed, and the prosthesisis prepared for delivery (Fig. 7). Fig. 6. Three-piece mold with acrylic resin core and finished prosthesis. Note core shows relief areas for three magnets (i.e., superior and both lateral alae).
SUMMARY A technique has been presented describingthe fabrication of an acrylic resin core for a silicone nasalprosthesis. This technique ensuresa durable core that can be usedrepeatedly. The coreresistsfungal growth during storageand provides a smooth,easily cleanableinternal surfacefor the prosthesis. It is also compatible with several microwave curing techniques.* Such acrylic resin cores may also be used as the third mold element in other siliconefacial prosthesismoldswhen it is desirableto keep the prosthesisthin and light. REFERENCES 1. Udagama DENT
Fig. 7. Internal surface of prosthesis processed with acrylic resin core. Note smooth internal surface (pointer).
powderratio and, whenthe resin isin the doughy stage, place it in both sidesof the mold. 7. Place polyethylene sheetsbetween the two halves of the mold and trial pack one or two times prior to removing the polyethylene sheetsand closingthe flask.
376
A. Urethane-lined
silicone
facial prostheses.
J PROSTHET
1987;58:351-4.
2. Veres EM, Wolfaardt JF, Becker PJ. An evaluation of the surface characteristics of a facial prosthetic elastomer. Part I. Review of the literature on the surface characteristics of dental materials with maxillofacial prosthetic application. J PROSTHET DENT 1990;63:193-7. 3. DeClerck JP. Microwave polymerization of acrylic resins used in dental prostheses. J PROSTHET DENT 1987;57:650-8. 4. Seals RR Jr, Cortes AL, Funk JL, Pare1 SM. Microwave techniques for fabrication of provisional facial prostheses. J PHOSTHET DENT 1989; 62:327-31. Reprint requests to: DR. JAMES C. LEMON DEPARTMENT OF DENTAL ONCOLOGY, Box 9 UNIVEWTY OF TEXAS, M. D. ANDERSON CANCER 1515 HOLCOMBE BLVD. HOUSTON, TX 77030
*Pagan
WJ. Personal
communication,
MARCH
CENTER
1990.
1992
VOLUME
67
NUMBER
3
