- Email: [email protected]
Fabrication of facial prostheses by applying the osseointegration concept for retention
DENISSEN ET AL
7. Williams DF, Roaf R. Implants in surgery. WB Saunders Co, Ltd 1973. 8. Denissen HW, van Dijk HJA, Gehring AP, de Groot K. Preparation of densely sintered calcium hydroxylapatite. J Dent Res 1979;42:551-6. 9. Denissen HW, Veldhuis AAH, van Faassen F. Implant placement in the atrophic mandible: an anatomical study. J PROSTHET DENT 1984;52: 260-3_ 10_ Dneheyne P., van Raemdonk W., de Meester P. Physical and material properties of hydroxylapatite coatings sintered on titanium. Biomaterials Transactions 1984;7:350.
Reprint requests to: DR_ HARRY W. DENISSEN UNIVERSITY OF N'~CMEGEN DENTAL SCHOOL P.O. BOX9101 6500 HB N~MEGEN THE NETHERLANDS
Fabrication of facial p r o s t h e s e s by applying the o s s e o i n t e g r a t i o n concept for retention R i c h a r d R. S e a l s , Jr., D.D.S., M.Ed., M.S.,* A q u i l e o L. C o r t e s , B.S., M.A.,** a n d S t e p h e n M. P a r e l , D.D.S.***
The University of Texas Health Science Center at San Antonio, Dental School, San Antonio, Tex. Initial clinical studies applying the o s s e o i n t e g r a t i o n concept for retention of facial p r o s t h e s e s h a v e been encouraging. The results of these preliminary i n v e s t i g a t i o n s indicate n e w treatment possibilities with facial p r o s t h e s e s anchored to the cranial s k e l e t o n by o s s e o i n t e g r a t e d implants. O s s e o i n t e g r a t e d rehabilitation of the m a x i l l o f a c i a l prosthetic patient presents the potential for o v e r c o m i n g many of the d i s a d v a n t a g e s associated with conventional r e t e n t i v e methods. Fabrication and support for facial prostheses by using o s s e o i n t e g r a t e d implants for retention are described. (J PROSTHET DENT 1989;61:712-16.)
T h e history of osseointegrated implants, with carefully documented animal experiments 1-3 and corresponding clinical studies 4-1° has documented favorable results using commercially pure titanium implants. The achievements of osseointegrated implantology are based on an atraumatic surgical procedure, a specific metallurgic response, an initial implant healing period without loading, and a passive stress-distributed prosthetic technique. 11 Together these factors contribute to a predictably high degree of implant longevity and long-term prosthesis use. Clinicians providing facial prostheses have been searching for improved retentive media. In some clinical situations mechanical retention, such as tissue undercuts.or conformers, can be used, but most patients have to rely on aromatic ostomy cements, two-sided tapes, and water soluble or silicone base adhesives. Each of the retentive media, whether cements, tapes, or adhesives, have significant drawbacks.12,13 Osseointegrated implant rehabilitation offered the first real promise for overcoming many of the disadvantages associated with conventional retentive media. If stable, bone-anchored implants could permanently pene-
Supported by an American Cancer Society Clinical OncologyCareer Development Award_ *Assistant Professor, Department of Prosthodontics. **Assistant Professor, Dental Laboratory Technology Program; Certified Dental Technician. ***Professor, Department of Prosthodonties712
Fig. 1. A, Osseointegrated implants with bar-splint assembly and magnetic retainers. B, Nasal prosthesis in place. JUNE 1988 VOLUME 61 NUMBER e
FAF;RI('ATI(~N tW I'A('IAI
I R O S T I I I , I S ,,IS
Fig. 2. Transcutaneous abutments for auricular prosthesis. Note delayed healing indicated by grarulation tissue around one abutment. Fig. 3. Cast ngs indexed to gold cylinders.
trate the skin. new p,~,ssibilities in maxillofacial prosthetic rehal)ilitati(m w(~uld be available. Based ()n the p(~siti\ e results (,btained by using osseointe grated implants in th( dental rehabilitation of the edentulous mandible and maxillae. ~ decision was made to test whether the lavotabh, outcomes associated with intraoral implants c(mld be ex~ended t() the head and neck region. Branemark and his issociates first placed modified osseointegrated [ixtureb in the tranial skeleton for the purposes of retaining bo~ e-conduction hearing aids and auric ular prosthe~es. 11. i, l, Since that time, a variety of facial de fects have been res~()red with osseointegrated fixtures providing a cetentiv,, base (,f remarkable strength and p,:)tentially great hmg,wity_ 1: 1; Facial t)roslheses e,n he a n d m r e d to implant abutments in one of tw,~ ways: a bar-splil.t assembly with ('lip attachn:tents (~r a b a r splin~ assembly with paired magnets. The Swedish implant teal:~ initmlly used a bar-splint assembly with clip atlachment s: ~5 (?.lip a~tachments provide excellent retention in the regioll of the I,ar but only limited marginal stability for iarge re>t.()rati(m:~. Furthermore, clip a t t a c h menls complicate fab~'icati~)n in that they must be retained in an acrylic resin ba.~e that is in turn incorporated int(J the prosthesis. The combi ning of p ~ired magnetic retainers with bar-splint assemblies ~'esults in prostheses with excellent re tentive qualities. Pair=~d magn¢ tic retainers allow placernent of relativeb h,w-pro~le reten:ive units that minimize e s thetic surfac( c(mq)r, mise and allow ttexibility in the ]()t'~l TItE JO[IRNAL
O F P R O S F H E T I C D ~]NTIS'FRY
titm of the retainers to improve margin adaptation and stability (Fig. 1).1~ The results of these preliminary inw~stigations point to new treatment possibilities using external prostheses anchored to the cranial skeleton. This article describes the support for and the fabrication of facial iorostheses applying the osseointegration concept for retention.
PROSTHESIS FABRICATION After initial sm'gery the implant fixtures are allowed to integrate fl)r 5 to) 6 months. During this time a facial prosthesis retained by conventional retentive media can be used. Abutment placement requires a second surgical procedure. The existing prosthesis is modified to accommodate ~he abutments and a pressure dressing is applied for a 2 week healing periodJ ~ It is imperative with transcutaneous abutments t~) prevent free skin movement around the implant. 16 After res[)lution of postoperative edema, impressions are made t(~ accurately record the positi(m ot the abutments. impressions can usually be made wi~;hin 3 to 4 weeks, depending on patient comfort, healing progress, and clinical judgment (Fig. 2). Tapered transfer copings with vertical screws are mounted on the implant abutments. Polyether elastt,meric impression material (Premier, Norristown, Pa.) is carefully injected around and between the implant abutments and transfer copings. Special care, is needed to ensure the placement ~>f impressien material into the mechanical 713
SEALS, CORTES, AND P A H E L
Fig. 4. A, Bar-splint assembly on working cast. B, Assembly with accurate, passive fit on implant abutments.
Fig. 5. Processing cast for nasal prosthesis. Fig. 6. Positioning paired magnets with wire rosettes on auricular processing cast.
undercuts of the tapered transfer copings. As the silicone impression material gains body, the borders of the impression are smoothed and shaped to create lateral undercuts and keys in the impression material. Once the silicone impression has set, an irreversible hydrocolloid impression outlining the defect area is made with the silicone impression in place. After the irreversible hydrocolloid impression material sets, the two impressions are carefully removed, first the irreversible hydrocolloid, then the silicone impression material. The transfer copings are unscrewed from the implant abutments and brass abutment analogues are mounted on the copings. The transfer copings, with attached abutment analogues, are repositioned in the sillcone impression material. The silicone impression is then keyed back into the irreversible hydrocolloid impression. The reassembled impressions are inspected for accuracy and positioning errors. The working cast is poured and a replica of the implant abutments is available for barsplint design and waxing. Gold alloy cylinders are screwed onto the abutment analogues and waxing of the bar-splint framework is initiated. A wax pattern is created by using 14-gauge round wax forms
(Kerr Laboratory Products Division, Emeryville, Calif.) with extensions into regions of the proposed prosthesis that will be thick enough to allow the placement of paired magnetic retainers without compromising esthetics. The pattern is waxed directly to the gold cylinders by using a point-contact to allow eventual soldering of the bar-splint to the gold cylinders. Multiple-sided receptors are created in the wax pattern to house each of the magnets. Receptacles are waxed with closed bases to prevent posterior dislodgement of the magnets and lateral undercuts to provide mechanical retention when the magnets are luted to the bar-splint. Multiplesided receptors are used to prevent rotational movement of the magnets within the receptacles. All bar-splint components are established several millimeters above the cast surface for patient hygiene and access. The wax pattern is cast in type IV gold by using conventional spruing, investing, and casting techniques for gold alloys. The ensuing casting is recovered, cleaned, and reoriented on the cast. The relationship of the bar to the gold cylinders is established by using the point contact waxed into the pattern and indexed with Duralay (Reliance Dental Mfg. Co., Worth, Ill.) material (Fig. 3). The bars and gold cylin-
714
J U N E 1989
V O L U M E 61
NUMBER 6
F A B R I C A T I O N OF F A C I A L P I ( O S T H E S E g
ders attached to the brass a b u t m e n t analogues are invested and then soldered to create a bar-splint assembly to support the :facial prosthesis. The bar-spli nt assembly should provide a strong and rigid metallic unit t h a t fulfills objectives of strength, support, nontissue impingement, and noninterference with the desired contour of the prosthesis. The bar-splint assembly is first tried on the working cast and then on the implant abutments. An accurate and passive fit is necessary to avoid adverse stress on one or more of the osseointegrated fixtures. If the assembly fails to fit the abutments, it is sectioned; an index is made, and the assembly is resoldered. When an absolutely passive fit has been verified, the cast assembly is finished and polished. Samarium-cobalt magnets (Jobmaster Corp., Randalstown, Md.) 4 x 4 mm in size are encapsulated in acrylic resin for protection and embedded in each receptacle on the bar-splint assembly with additional autopolymerizing resin (Fig. 4). The paired attracting magnets are resin-encapsulated with wire rosettes attached to the nonmating surface_ The wire rosettes are subsequently processed into the silicone of the prosthesis to provide retention between the silicone and the resin encapsulating the magnets. Attracting magnets with wire rosettes are also used during the fabrication of the processing cast. An irreversible hydrocolloid m~pression oatlining :he defect is made with the bar-splint assembly mortared on the implant abutments and the paired attracting magnets are positioned over each cantilevered magnetic rec~ptacle on the bar-splint assembly. The impression, with attracting magnets and wire rosettes incorporated, is remow~d and inspected_ Extra magnets are adapted to the magnet,- incorpo:ated in the irreversible hydrocolloid impression. A proce:~sing cast is poured and a replica of the magnetic retentive units within the facial defeet is available for prosthesis f~brication (Fig. 5)_ After the cast is separated from 1he impression, the magnets and wire rosettes are retriew~d from the ilreversible hydrocolloid material. The prosthesis is sculpted tc size and contour with the paired magnets incorporated into the modeling material_ Once again the bar-spiint framework is assembled on the patient and final modeling is achieved. Esthetics, tit, and retention are evaluated~ A stone mold is produced in a conventional manner. The paired magnets embedded in acrylic resin with wire rosettes are repositioned on the cast (Fig. 6)_ Siliome rubber (MDXt-4210, Dow Corning Corp., Midland, Mich_) is added slowly to the mold to ensure t h a t the rosettes are completely enc(rcled. The facial prosthesis is processed and delivered with a combination of intrinsic and extrinsic colorati¢,n procedures to match the existing adjacent skin tones (Fig. 7L Th? patient is instructed to lubricate the skin arom~d the borders of the defect (White Petrolatum, lISP, Comatic L~boratories, inc., Houston, Tex.~, position the pr,:,sthesis, and with gentle finger pressure a d a p t ~he margins of the prosthesis to the tissue lFig. 8)_
THE J O U R N A L OF P R O S T H E T I C D E N T I S T R Y
F i g . 7. A, Processmg cast and tissue surface of auricular prosthesis. B, Paired magnet embedded in prosthesis.
SUMMARY One of the most exciting aspects of osseointegrated implants is the potential for rehabilitation of the maxillofacial patient. Preliminary experience with auricular, nasal, and orbital prostheses at t r e a t m e n t centers in G6teborg, Sweden and the University of Texas Health Science Center at San Antonio has been encouraging. Prostheses t h a t are superior in terms of convenience and wear have been made for patients with facial defects. 17 The application of osseointegrated fixtures to the cranial skeleton for facial prosthesis retention minimizes problems with marginal integrity, placement misalignment, and prosthesis camouflage {Fig. 9). Perhaps the most significant advancement is the ability to diminish dependence on adhesives and therefore eliminate adhesive-induced material degeneration/discoloration and skin reactions. The fabrication of and support for facial prostheses by using osseointegrated implants for retention has been described. The application of these concepts and procedures to patients with congenital or acquired facial defects has the potential nf dramatically increasing the level of their functional rehabilitation.
715
SEALS, CORTES, AND PAREL
Fig. 8. Auricular prosthesis in place without adhesive. Fig. 9. Prosthesis applying osseointegration retention to minimize problems with marginal integrity, alignment, and camouflage.
REFERENCES 1. Branemark P-I, Lindstrom J. A modified rabbit's ear chamber. Anat Rec 1963;145:533-40. 2. Branemark P-I, Breine U. Formation of bone marrow in isolated segment of rib periosteum in rabbit and dog. Blut 1964;10:236. 3. Branemark P-I, Breine U, Adell R, Hansson BO, Lindstrom J, Ohlsson A. Intra-osseous anchorage of dental prostheses. 1. Experimental studies. Scand J Plast Reconstr Surg 1969;3:81-100. 4. Branemark P-I, Lindstrom J, Hallen O, Breine U, Hansson B. Repair of defects in mandible, Scand J Plast Reconstr Surg 1970;4:100-8. 5. Branemark P-I, Lindstrom J, Hallen O, Breine U, Jeppson P-H, Oman A. Reconstruction of the defective mandible. Scand J Plast Reconstr Surg 1975;9:116-28. 6. Adell R, Lekholm U, Rockier B, Branemark P-L A 15-year study of osseointegrated implants in the treatment of the edentulous jaw. Int J Oral Surg 1981;6:387-416. 7_ Branemark P-I. Osseointegration and its experimental background. J PROSTHET DENT 1983;50:399-410. 8. Adell R. Clinical results of osseointegrated implants supporting fixed prostheses in edentulous jaws- J PROSTHET DENT 1983;50:251-4. 9. Lekholm U- Clinical procedures for treatment with osseointegrated dental implants. J PROSTHET DENT 1983;50:116-20. 10. Zarb GA, Symington JM. Osseointegrated dental implants: preliminary report on a replication study J PROSTHET DENT 1982;50:271-6.
716
11. Branemark P-I, Albrektsson T. Tieonium implants permanently penetrating human skin. Scand J Plast Reconstr Surg 1982;16:17-21. 12. Parel, SM, Branemark P-I, Tjellstrom A, Gion G. Osseointegration in maxillofacial prosthetics. Part II: extraoral applications. J PROSTHET DENT 1986;55:600-6. 13. Parel SM. Diminishing dependence on adhesives for retention of facial prostheses. J PROSTHET DENT 1980;43:552-6ff 14. Tjellstrom A, Hakansson B, Lindstrom J, et al. Analysis of the mechanical impedance of bone-anchored hearing aids. Acta Otolaryngol 1980; 89:85-92. 15. Tjellstrem A, Lindstrom J, Nylen O, eL al. The bone anchored auricular episthesis. Laryngoscope 1981;91:811-5_ 16. Tjellstrom A, Rosenhall U, Lindstrom J, Hallen O, Albrektsson T, Branemark P-I. Five-year experience with skin-penetrating bone-anchored implants in the temporal bone. Acta Otolaryngol 1983;95:568-75. 17. Parel SM, Holt GA, Branemark P-I, Tjellstrom A. Osseointegration and facial prosthetics. Int J Oral Maxillofac Implants 1986;1:27-9. Reprint requests to: DR. RICHARDR. SEALS, JR. THE UNIVERSITYOF TEXAS HEALTH SCIENCE CENTER AT SAN ANTONIO DENTAL SCHOOL SAN ANTONIO. TX 78284-7912
J U N E 1989
VOLUME 61
NUMBER 6
7. Williams DF, Roaf R. Implants in surgery. WB Saunders Co, Ltd 1973. 8. Denissen HW, van Dijk HJA, Gehring AP, de Groot K. Preparation of densely sintered calcium hydroxylapatite. J Dent Res 1979;42:551-6. 9. Denissen HW, Veldhuis AAH, van Faassen F. Implant placement in the atrophic mandible: an anatomical study. J PROSTHET DENT 1984;52: 260-3_ 10_ Dneheyne P., van Raemdonk W., de Meester P. Physical and material properties of hydroxylapatite coatings sintered on titanium. Biomaterials Transactions 1984;7:350.
Reprint requests to: DR_ HARRY W. DENISSEN UNIVERSITY OF N'~CMEGEN DENTAL SCHOOL P.O. BOX9101 6500 HB N~MEGEN THE NETHERLANDS
Fabrication of facial p r o s t h e s e s by applying the o s s e o i n t e g r a t i o n concept for retention R i c h a r d R. S e a l s , Jr., D.D.S., M.Ed., M.S.,* A q u i l e o L. C o r t e s , B.S., M.A.,** a n d S t e p h e n M. P a r e l , D.D.S.***
The University of Texas Health Science Center at San Antonio, Dental School, San Antonio, Tex. Initial clinical studies applying the o s s e o i n t e g r a t i o n concept for retention of facial p r o s t h e s e s h a v e been encouraging. The results of these preliminary i n v e s t i g a t i o n s indicate n e w treatment possibilities with facial p r o s t h e s e s anchored to the cranial s k e l e t o n by o s s e o i n t e g r a t e d implants. O s s e o i n t e g r a t e d rehabilitation of the m a x i l l o f a c i a l prosthetic patient presents the potential for o v e r c o m i n g many of the d i s a d v a n t a g e s associated with conventional r e t e n t i v e methods. Fabrication and support for facial prostheses by using o s s e o i n t e g r a t e d implants for retention are described. (J PROSTHET DENT 1989;61:712-16.)
T h e history of osseointegrated implants, with carefully documented animal experiments 1-3 and corresponding clinical studies 4-1° has documented favorable results using commercially pure titanium implants. The achievements of osseointegrated implantology are based on an atraumatic surgical procedure, a specific metallurgic response, an initial implant healing period without loading, and a passive stress-distributed prosthetic technique. 11 Together these factors contribute to a predictably high degree of implant longevity and long-term prosthesis use. Clinicians providing facial prostheses have been searching for improved retentive media. In some clinical situations mechanical retention, such as tissue undercuts.or conformers, can be used, but most patients have to rely on aromatic ostomy cements, two-sided tapes, and water soluble or silicone base adhesives. Each of the retentive media, whether cements, tapes, or adhesives, have significant drawbacks.12,13 Osseointegrated implant rehabilitation offered the first real promise for overcoming many of the disadvantages associated with conventional retentive media. If stable, bone-anchored implants could permanently pene-
Supported by an American Cancer Society Clinical OncologyCareer Development Award_ *Assistant Professor, Department of Prosthodontics. **Assistant Professor, Dental Laboratory Technology Program; Certified Dental Technician. ***Professor, Department of Prosthodonties712
Fig. 1. A, Osseointegrated implants with bar-splint assembly and magnetic retainers. B, Nasal prosthesis in place. JUNE 1988 VOLUME 61 NUMBER e
FAF;RI('ATI(~N tW I'A('IAI
I R O S T I I I , I S ,,IS
Fig. 2. Transcutaneous abutments for auricular prosthesis. Note delayed healing indicated by grarulation tissue around one abutment. Fig. 3. Cast ngs indexed to gold cylinders.
trate the skin. new p,~,ssibilities in maxillofacial prosthetic rehal)ilitati(m w(~uld be available. Based ()n the p(~siti\ e results (,btained by using osseointe grated implants in th( dental rehabilitation of the edentulous mandible and maxillae. ~ decision was made to test whether the lavotabh, outcomes associated with intraoral implants c(mld be ex~ended t() the head and neck region. Branemark and his issociates first placed modified osseointegrated [ixtureb in the tranial skeleton for the purposes of retaining bo~ e-conduction hearing aids and auric ular prosthe~es. 11. i, l, Since that time, a variety of facial de fects have been res~()red with osseointegrated fixtures providing a cetentiv,, base (,f remarkable strength and p,:)tentially great hmg,wity_ 1: 1; Facial t)roslheses e,n he a n d m r e d to implant abutments in one of tw,~ ways: a bar-splil.t assembly with ('lip attachn:tents (~r a b a r splin~ assembly with paired magnets. The Swedish implant teal:~ initmlly used a bar-splint assembly with clip atlachment s: ~5 (?.lip a~tachments provide excellent retention in the regioll of the I,ar but only limited marginal stability for iarge re>t.()rati(m:~. Furthermore, clip a t t a c h menls complicate fab~'icati~)n in that they must be retained in an acrylic resin ba.~e that is in turn incorporated int(J the prosthesis. The combi ning of p ~ired magnetic retainers with bar-splint assemblies ~'esults in prostheses with excellent re tentive qualities. Pair=~d magn¢ tic retainers allow placernent of relativeb h,w-pro~le reten:ive units that minimize e s thetic surfac( c(mq)r, mise and allow ttexibility in the ]()t'~l TItE JO[IRNAL
O F P R O S F H E T I C D ~]NTIS'FRY
titm of the retainers to improve margin adaptation and stability (Fig. 1).1~ The results of these preliminary inw~stigations point to new treatment possibilities using external prostheses anchored to the cranial skeleton. This article describes the support for and the fabrication of facial iorostheses applying the osseointegration concept for retention.
PROSTHESIS FABRICATION After initial sm'gery the implant fixtures are allowed to integrate fl)r 5 to) 6 months. During this time a facial prosthesis retained by conventional retentive media can be used. Abutment placement requires a second surgical procedure. The existing prosthesis is modified to accommodate ~he abutments and a pressure dressing is applied for a 2 week healing periodJ ~ It is imperative with transcutaneous abutments t~) prevent free skin movement around the implant. 16 After res[)lution of postoperative edema, impressions are made t(~ accurately record the positi(m ot the abutments. impressions can usually be made wi~;hin 3 to 4 weeks, depending on patient comfort, healing progress, and clinical judgment (Fig. 2). Tapered transfer copings with vertical screws are mounted on the implant abutments. Polyether elastt,meric impression material (Premier, Norristown, Pa.) is carefully injected around and between the implant abutments and transfer copings. Special care, is needed to ensure the placement ~>f impressien material into the mechanical 713
SEALS, CORTES, AND P A H E L
Fig. 4. A, Bar-splint assembly on working cast. B, Assembly with accurate, passive fit on implant abutments.
Fig. 5. Processing cast for nasal prosthesis. Fig. 6. Positioning paired magnets with wire rosettes on auricular processing cast.
undercuts of the tapered transfer copings. As the silicone impression material gains body, the borders of the impression are smoothed and shaped to create lateral undercuts and keys in the impression material. Once the silicone impression has set, an irreversible hydrocolloid impression outlining the defect area is made with the silicone impression in place. After the irreversible hydrocolloid impression material sets, the two impressions are carefully removed, first the irreversible hydrocolloid, then the silicone impression material. The transfer copings are unscrewed from the implant abutments and brass abutment analogues are mounted on the copings. The transfer copings, with attached abutment analogues, are repositioned in the sillcone impression material. The silicone impression is then keyed back into the irreversible hydrocolloid impression. The reassembled impressions are inspected for accuracy and positioning errors. The working cast is poured and a replica of the implant abutments is available for barsplint design and waxing. Gold alloy cylinders are screwed onto the abutment analogues and waxing of the bar-splint framework is initiated. A wax pattern is created by using 14-gauge round wax forms
(Kerr Laboratory Products Division, Emeryville, Calif.) with extensions into regions of the proposed prosthesis that will be thick enough to allow the placement of paired magnetic retainers without compromising esthetics. The pattern is waxed directly to the gold cylinders by using a point-contact to allow eventual soldering of the bar-splint to the gold cylinders. Multiple-sided receptors are created in the wax pattern to house each of the magnets. Receptacles are waxed with closed bases to prevent posterior dislodgement of the magnets and lateral undercuts to provide mechanical retention when the magnets are luted to the bar-splint. Multiplesided receptors are used to prevent rotational movement of the magnets within the receptacles. All bar-splint components are established several millimeters above the cast surface for patient hygiene and access. The wax pattern is cast in type IV gold by using conventional spruing, investing, and casting techniques for gold alloys. The ensuing casting is recovered, cleaned, and reoriented on the cast. The relationship of the bar to the gold cylinders is established by using the point contact waxed into the pattern and indexed with Duralay (Reliance Dental Mfg. Co., Worth, Ill.) material (Fig. 3). The bars and gold cylin-
714
J U N E 1989
V O L U M E 61
NUMBER 6
F A B R I C A T I O N OF F A C I A L P I ( O S T H E S E g
ders attached to the brass a b u t m e n t analogues are invested and then soldered to create a bar-splint assembly to support the :facial prosthesis. The bar-spli nt assembly should provide a strong and rigid metallic unit t h a t fulfills objectives of strength, support, nontissue impingement, and noninterference with the desired contour of the prosthesis. The bar-splint assembly is first tried on the working cast and then on the implant abutments. An accurate and passive fit is necessary to avoid adverse stress on one or more of the osseointegrated fixtures. If the assembly fails to fit the abutments, it is sectioned; an index is made, and the assembly is resoldered. When an absolutely passive fit has been verified, the cast assembly is finished and polished. Samarium-cobalt magnets (Jobmaster Corp., Randalstown, Md.) 4 x 4 mm in size are encapsulated in acrylic resin for protection and embedded in each receptacle on the bar-splint assembly with additional autopolymerizing resin (Fig. 4). The paired attracting magnets are resin-encapsulated with wire rosettes attached to the nonmating surface_ The wire rosettes are subsequently processed into the silicone of the prosthesis to provide retention between the silicone and the resin encapsulating the magnets. Attracting magnets with wire rosettes are also used during the fabrication of the processing cast. An irreversible hydrocolloid m~pression oatlining :he defect is made with the bar-splint assembly mortared on the implant abutments and the paired attracting magnets are positioned over each cantilevered magnetic rec~ptacle on the bar-splint assembly. The impression, with attracting magnets and wire rosettes incorporated, is remow~d and inspected_ Extra magnets are adapted to the magnet,- incorpo:ated in the irreversible hydrocolloid impression. A proce:~sing cast is poured and a replica of the magnetic retentive units within the facial defeet is available for prosthesis f~brication (Fig. 5)_ After the cast is separated from 1he impression, the magnets and wire rosettes are retriew~d from the ilreversible hydrocolloid material. The prosthesis is sculpted tc size and contour with the paired magnets incorporated into the modeling material_ Once again the bar-spiint framework is assembled on the patient and final modeling is achieved. Esthetics, tit, and retention are evaluated~ A stone mold is produced in a conventional manner. The paired magnets embedded in acrylic resin with wire rosettes are repositioned on the cast (Fig. 6)_ Siliome rubber (MDXt-4210, Dow Corning Corp., Midland, Mich_) is added slowly to the mold to ensure t h a t the rosettes are completely enc(rcled. The facial prosthesis is processed and delivered with a combination of intrinsic and extrinsic colorati¢,n procedures to match the existing adjacent skin tones (Fig. 7L Th? patient is instructed to lubricate the skin arom~d the borders of the defect (White Petrolatum, lISP, Comatic L~boratories, inc., Houston, Tex.~, position the pr,:,sthesis, and with gentle finger pressure a d a p t ~he margins of the prosthesis to the tissue lFig. 8)_
THE J O U R N A L OF P R O S T H E T I C D E N T I S T R Y
F i g . 7. A, Processmg cast and tissue surface of auricular prosthesis. B, Paired magnet embedded in prosthesis.
SUMMARY One of the most exciting aspects of osseointegrated implants is the potential for rehabilitation of the maxillofacial patient. Preliminary experience with auricular, nasal, and orbital prostheses at t r e a t m e n t centers in G6teborg, Sweden and the University of Texas Health Science Center at San Antonio has been encouraging. Prostheses t h a t are superior in terms of convenience and wear have been made for patients with facial defects. 17 The application of osseointegrated fixtures to the cranial skeleton for facial prosthesis retention minimizes problems with marginal integrity, placement misalignment, and prosthesis camouflage {Fig. 9). Perhaps the most significant advancement is the ability to diminish dependence on adhesives and therefore eliminate adhesive-induced material degeneration/discoloration and skin reactions. The fabrication of and support for facial prostheses by using osseointegrated implants for retention has been described. The application of these concepts and procedures to patients with congenital or acquired facial defects has the potential nf dramatically increasing the level of their functional rehabilitation.
715
SEALS, CORTES, AND PAREL
Fig. 8. Auricular prosthesis in place without adhesive. Fig. 9. Prosthesis applying osseointegration retention to minimize problems with marginal integrity, alignment, and camouflage.
REFERENCES 1. Branemark P-I, Lindstrom J. A modified rabbit's ear chamber. Anat Rec 1963;145:533-40. 2. Branemark P-I, Breine U. Formation of bone marrow in isolated segment of rib periosteum in rabbit and dog. Blut 1964;10:236. 3. Branemark P-I, Breine U, Adell R, Hansson BO, Lindstrom J, Ohlsson A. Intra-osseous anchorage of dental prostheses. 1. Experimental studies. Scand J Plast Reconstr Surg 1969;3:81-100. 4. Branemark P-I, Lindstrom J, Hallen O, Breine U, Hansson B. Repair of defects in mandible, Scand J Plast Reconstr Surg 1970;4:100-8. 5. Branemark P-I, Lindstrom J, Hallen O, Breine U, Jeppson P-H, Oman A. Reconstruction of the defective mandible. Scand J Plast Reconstr Surg 1975;9:116-28. 6. Adell R, Lekholm U, Rockier B, Branemark P-L A 15-year study of osseointegrated implants in the treatment of the edentulous jaw. Int J Oral Surg 1981;6:387-416. 7_ Branemark P-I. Osseointegration and its experimental background. J PROSTHET DENT 1983;50:399-410. 8. Adell R. Clinical results of osseointegrated implants supporting fixed prostheses in edentulous jaws- J PROSTHET DENT 1983;50:251-4. 9. Lekholm U- Clinical procedures for treatment with osseointegrated dental implants. J PROSTHET DENT 1983;50:116-20. 10. Zarb GA, Symington JM. Osseointegrated dental implants: preliminary report on a replication study J PROSTHET DENT 1982;50:271-6.
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11. Branemark P-I, Albrektsson T. Tieonium implants permanently penetrating human skin. Scand J Plast Reconstr Surg 1982;16:17-21. 12. Parel, SM, Branemark P-I, Tjellstrom A, Gion G. Osseointegration in maxillofacial prosthetics. Part II: extraoral applications. J PROSTHET DENT 1986;55:600-6. 13. Parel SM. Diminishing dependence on adhesives for retention of facial prostheses. J PROSTHET DENT 1980;43:552-6ff 14. Tjellstrom A, Hakansson B, Lindstrom J, et al. Analysis of the mechanical impedance of bone-anchored hearing aids. Acta Otolaryngol 1980; 89:85-92. 15. Tjellstrem A, Lindstrom J, Nylen O, eL al. The bone anchored auricular episthesis. Laryngoscope 1981;91:811-5_ 16. Tjellstrom A, Rosenhall U, Lindstrom J, Hallen O, Albrektsson T, Branemark P-I. Five-year experience with skin-penetrating bone-anchored implants in the temporal bone. Acta Otolaryngol 1983;95:568-75. 17. Parel SM, Holt GA, Branemark P-I, Tjellstrom A. Osseointegration and facial prosthetics. Int J Oral Maxillofac Implants 1986;1:27-9. Reprint requests to: DR. RICHARDR. SEALS, JR. THE UNIVERSITYOF TEXAS HEALTH SCIENCE CENTER AT SAN ANTONIO DENTAL SCHOOL SAN ANTONIO. TX 78284-7912
J U N E 1989
VOLUME 61
NUMBER 6