Osseointegration in maxillofacial prosthetics. Part II: Extraoral applications

Ossec,lintegratiton in max ihfacid. Extraowal ;tpplications

hfftics. Part II:

Stephen IVI. Pare& D.D.S.,* P-I. Bra:nemark, h4.D1.,** Andexs Tf&&trom, and Greg Gion****

M.D.,**+

Unzversity cd Texas Health Science Center, Dental School, !,an Antonio, Tex., Institute for Applied Biotechnolog? and Sahlgren; Hospital, Giitebo.g, Sweden

U

sing principles of bone repair enhancement through atraumatic surgical technique and titanurn metal sur-. face technology, Branemarkg and his associates first placed modified osseointegrated fixtures in the cranial skeleton for the purpose of retainiag a prosthetic ear in 1977. This was perhaps the most significant advance in the field of facial prosthetic restoration in the past 25 years. Since that time, a variety of facial defects have been restored with these fixtures, providing a retentive base of remarkable strength and potentially great longevity.‘-*

REDUCING ADHESIVE DEPEPJDENCE Clinicians providing artificial body parts have continued to search for the perfect retentive medium. Although technology has evolved sigtificantly from crude me&anical devices or sticky, irritant spirit gum derivatives, there are still inherent problems in the use of adhesives.’ At times mechanical means, such as tissue undercuts or conformers for retention can be used but most patients have to rely on aromatic ostomy cements, two-sided tapes, and water soluble or silicone base adhesives. Each adhesive has its own limitations, particularly in the facial region. Tapes usually will not stick to silicone and require trimming daily (Fig. 1). This may cause inadvertent margin loss and subsequent unesthetic thick edges. The paste or liquid aromatic cements require daily removal, which can frictionally damage the extrinsic coloration of the facial surface (Fig. 2). Somepatients will also develop allergic reactions to these substances, even when worn only during waking hours. The silicone base adhesives are extremely retentive on silicone pros-

Presentedbefore the Academy of Denture Prosthetics,Hilton Head, S.C. *Professor and Head, Division of Maxillofacial Prosthetics, Department of Prosthodontics, University of Texas Health Science Center, Dental School. **Director, Institute for Applied Biotechnology, GBteborg, Sweden. ***Mead of Otolcgy, Sahlgrens Hospital, G&eborg, Sweden. ****Medical Sculptor, University of Texas Health Science Center, Dental School. QBranemark P-I: Personal communication, 1982. 600

theses and tend to damage fine margins~ with d&y prosthesis use. They also require a silicone solvent for adhesive cleansing, which will deteriorate the base material if injudiciously used. Adhesives may also limit the patient’s sense of security and may encourage reclusive activity. Patients with altered skin sensation may be unaware of a lwsesitig or fallen prosthesis and others will tend to lose the adhesive bond in regions where perspiration can affect the in&face. Given these limitations, even the most esthetic restoration can be functionally compromised. Osseointegration technology offers the first real promise for overcQming these disadvantages in the app&priate patient.

SURGICAL PHASE Although implants developed for cranial app%+on are altered slightly in configuratim, tke surgi& t&hnique is based on the same approach -that proved successful in the oral cavity.‘O-l3 Adherence to sttict sterile surgical procedures, respect for the implant SW; face integrity, and atraumatic placemeat all; contribute to the ultimate success of the fixture-resteFa&m conple~, Not all patients with facial defects will be ca.nd$&tes for these procedures, particularly patients with~carti& inous peripheral tissue, or thick layers of skin th& cannot be reduced without causing further esthetic disfigurement. The bone in the postau&ulotem~~aJ region, superior lateral orbital rim, malar process; or superior maxillae are excellent sites for f&tire p&ement with appropriate access. Pilot holes are drilled with depth&nited burs to determine adequate receptor site thiekz&s~ and fix&e spacing. sizing is compkted with steel rotary Me cutting instruments, and a flat countersink is prepared with- an end cutting bur. Final site preparations are done with a~ titanium tap and copious cooiing at low revolutions of 10 to 15 RPM (Fig. 3). The. fixture is seated at similar speeds until bone shavings apptlar through the ffw perforations (Fig. 4). The fixtures are covered with a watertight skin closure and allowed to ifit-egrate&r 5 to 6 months. Abutment placement requires location of the fixtures MAY

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Fig. 1. Margin vulnerability sided tape application.

during

trimming

of two-

Fig. 2. Surface color damaged with frictional required to remove opposite surface adhesive.

effort

Table I. Summary of results with fixture and abutment complications in the Swedish experience between 1977 and 1984. (Redrawn and updated from the Proceedings of the Workshop on Craniofacial Reconstruction, Giiteborg, May 1982, Dr. Andres Tjellstrom.) Fixtures Year

Fixtures utimd

1977 1978 1979 1980 1981 1982 1983 1984 Total

4 10 4 25 12 60 84 45 244

Not inteRrated 0 0 0 0 0 2 0 0 2

Abutments removed

removed Other

Infection/ inflammation

0 1 0 0 0 0 0 I! 1

Other

0 0 0 0 0 3 0 0 3

Fig. 3. Tapping done with titanium exceptionally

through a flap reflection and puncture site (Fig. 5). It is critical at this stage to thin the skin flap significantly so that the epithelial cuff will adhere tightly to the abutment adjacent periosteuxn. A pressure dressing is then applied and reapplied over a 2-week healing period (Fig. 6).

PROSTHODONTIC

PROCEDURES

Use of anchorage units has been accomplished in two basic ways. The Swedish method initially used a barsplint assembly with gold clip attachments. These provide excellent retention in the region of the bar but may limit peripheral margin down-force on a large restoration. The clip-bar assemblies must be retained in an acrylic resin base that is in turn incorporated into the prosthesis, further complicating the construction process. Longevity of prosthesis use, however, is excellent with this technique, and patient satisfaction is high. THE JOURNAL OF PROSTHETIC DENTISTRY

low revolution

instruments

at

and copious irrigation.

Modifications of the anchorage units that allow flexibility in the location of retainers and potentially greater circumferential prosthesis adaptation have been proposed. Samarium-cobalt magnets &bmas&r Corp., Randalstown, Md.) are encapsulated in acrylic resin and are attached to extensions of the bar splint (Fig. 7). Paired magnets an also resin-encapsuiated with wire rosettes attached to the nonmating surface. They are transferred to the master impression and subsequently captured in the skin surface of the prosthesis (Fig. 8). This arrangement allows placement of relatively low profile retention units in regions of the prosthesis with enough depth to prevent compromise of the esthetic surface. It also allows retention to be placed remotely from the fixture base for greater peripheral margin fixation (Fig. 9). 601

PABEL

ET AL

Fig. 4. A, A 4 mm implant attached to rotary driving instrument. Implants are also placed atraumatically at exceedingly low speed with irrigation. B, Four flange type depth-limited osseointegmted implants placed in a superior orbital rim prior to final closure and healing.

Fig. 5. Implants exposed through after 5 l/2 months.

puncture incisions

Fig. 7. A 4 x 4 mm sanqr+m-cobalt tion unit embedded in a&yIic resin in sions of cast bar.

FiB. 6. Healing caps are unscrewed to allow removal of pressure dressing that has compacted epithehal c&for approximately 2 weeks. 602

comes nearly every adhesive-ret&red r extended longevity without MAY

retent&t&-

the necessity for constant

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Fig. 8. Definitive prosthesis with incorporated resin enclosed magnet retention units.

acrylic

Fig. 9. Definitive sive.

prosthesis

in place

without

adhe-

Fig. 10. A, Three osseointegrated implants placed in superior maxillae immediately inferior to piriform aperture. B, Healed osseointegrated implants penetrating skin graft. C, Design of magnetic retention superstructure. All units are several millimeters above skin surface for hygiene and access. D, Completed prosthesis without glasses frame. THE JOURNAL

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ET AL

Fig. 11. A, Placement of three implants in superior orbital rim and a single free standing implant in junction of nasal spine and superior maxiUae. $ Four-place magnetic retention unit secured to superior ‘@bital. rim fixtures. C, Single closed ,field magnetic retention unit was used to securi: prosthesis to free-standing lateral nasal fixture. D, Completed composite orbital pr&hesis in place without adhesives.

Table II. m experience abutments.

of fine semitransiucent nt,ges &hat-can bc easily maintained wiht only a petr?$~~@y inter&toe Recessa~ fbf skin adaptation.

of the San Antiio w$t;h extra0ral fixtures and

w!sFix&es pla& Not ink&ted Abutments remwed Abutments pending

,’

NOW

Orbit ;“-‘...*.‘*L’: 3 15 0 1 0 0 2 4

..l+ar

Other

9 0 0 7

O.2’ 0 0 1

remake or repair. Predimtbk and consistent retention has enhanced patient security to the point that patterns of social interactions have reportedly been improved. Margin integrity is maintained, allowing the fabrication 604

Any f&e& body considered for i oral c&y or cranial &t&Son 9 .ieveral criteria for stis.

implant (system) could be corn&&rod MAY

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Fig. 12. A, Failed lateral fixture supporting bar splint. Mobility indicated a lack of osseointegration. B, Free-standing fixtures supporting a new prosthesis using stronger retention magnets (Solid State Innovations, Mt. Airy, N.C.). C, Closed-field paired magnets embedded in prosthesis replacing flat magnets originally used for bar splint retention.

result was functioning satisfactorily after 5 years in 75% of patients treated. The initial Swedish experience exceeds this expectation of longevity with results compiled from 1977 (Table I). There is every indication that the life expectancy of these fixtures exceeds the Harvard criteria enough to suggest that a restatement of adequate longevity might be in order. Although more recent, the San Antonio extraoral experience appears to parallel that of the Europeans (Table II). l&&Wy. In the event of a failure, the patient should not suffer severe hard or soft tissue depletion. After implant removal, as with the Branemark system, there should be no significant change from the preoperative state. Bone fill in the vacated receptor site is nearly total, and adjacent hard and soft tissues are not adversely af&et& by the failure. l&t&~&&y. The entire prosthetic result should not be jeopardized by the failure of a single component unit. This is an inherent quality of the Branemark THE JOURNAL

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system; remaining fixtures can be modified to continue in the orginally anticipated service (Fig. 12). Function. The ultimate prosthetic result should provide a level of function commensurate with tbe expense and effort incurred to receive the implant system. Although there are no guarantees of success with any implant procedure, there is with this system a reasonable expectation that the patient will receive an appropriately successful functional unit.

SUMMARY The application of osseointegrated fixtures to the cranial skeleton for facial prosthesis retention marks a revolutionary step in the search for the perfect soft tissue replacement. They allow present elastomer technology to be used to its greatest potential by protecting surface coloration, eliminating adhesive-induced base material degeneration, and allowing the long-term retention of fine, but weak peripheral margins. Although not all 605

PAREI; ET AL

facial defect patients are can& the casqpt as applied in our proved to be a valuable rep adhesive systems.

8.

REFEREMCES 1. Tjellstrom A, Lindstrom J, Nylen 0, Albrektsson T, Branemark P-I, Nero H, Birgersson B: The bone anchored episthesis. Laryngoscope 91:811, 1981. 2. Branemark P-I, Albrektsson T: Titanium implants permanently penetrating human skin. Stand J Plast Reconstr Surg tE:17, 1982. 3. Tjellstrom A, Rosenhall U, Lindstram J, HaIlen 0, Albrektsson T, Branemark P-I: Five year experience with skin-penetrating bone-anchored implants is the temporal bone. Acta Gtolaryngol 95:568, 1983. 4. Tjellstrom A, Lindstrom J, Nylen 0, Albrcktsson T, Branemark P-I: Directly be&-&&ored implants for fixation of aural episthesis. Adv ~%%oqaterials4~55, 1983. 5. Albrektsson T, Brancmark P-I, Lindstrom J: Transcutaneous titanium implants‘in clinical practice. Adv Biomaterials 4:179, 1982. 6. Lindstrom J, TJelIstrom A: Clinical application of titanium implant in the &nporal bone. Proc Am ENT Academy Meeting, New Orleans, 1982. 7. Tjellstrom A, Hakansson B, Lindstrom J, Branemark P-I,

9. to.

11.

12.

13.

Ha&n Oj RoaebaII U, Leijon A: AnaIysis of the mechanical impedance of batt+anchored hearing aids. Acta Otolaryngol m&s, i980. Hakansson B, McQueen D, Tjellstrom A: Analysis of the mechanized skull impedance and a new transducer system for bone-apt&red hearing aids. Proc Intl Meeting on Biomedical Engineering, Linkoping, Sweden, 1981. Parei SM: Diminishing dependence on adhesives for retention of facial prostheses. j ~ROSTNET DENT 43:552, 1980. Adell R, Lekholm U, Rockier B, Branemark P-I, Lindhe J, Eriksson B, Sbordone L: Marginal tissue reactions at osseointegated titanium fixtures. I. A three year longitudinal prospective study. Intl J Oral Surg 1984. Zarb GA, Symington JM: Osseintegrated dental implants: Preliminary report on a replication study. J FROSTHET DENT 50:271, 1983. Adell R,Lekholm U, Rockier B, Branemark P-I: A 3 5 year study of osseointegrated implants in’ the treatment of the edentuious jaw. Int J Oral Surg l&387, 1981. Lekholm U: Clinical procedures for treatment with osseointea grated dental implants. J PR~STHETDENT 58:116, 1983.

Reprint requests to: DR. STEPHENM. PAREL

UNIVE.RS~OFTEXASHEALTHSCIENCE CENTER DENTAL SCHUOL SANAmorm, TX 78284

in, Ph.D.,* Thwald A. Cu&b, IMU.,** $G.,MS**** Center for the Health Sciences,University

T

of California, Los Angeles, Galif.

T

he avaikbiiity and ease of manipulation of acrylic resins have Ied to their increwxi use for restqin~~ la&e cranial defect~.‘~ The primary liitation of pr$wmed acrylic resin crank&&y is the de~tist’s iqab-ility to obtain an accurate cast of the cranial d&m fmm which an acrylic -in prosthesis can be ma&. Numerous Presented before the American Academy of Maxillofacial Prosthetics, Seattte, Wa&. *Assistant Professor, Department of Radiological Sciences, School of Medicine. **Resident, Maxillofacial Prosthetics, School of Dentistry. ***As&ant Professor; Removable Proatbndontics, School of Dentistv. *“t%?rofessor and Chairman, Removable Prnsthodontics, School of Dentistry.

MAY 1986

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