ic rehabilitation maxillectomy H. Devlin, FRCS
PhD,
MSc,
BSc,
BDSa
of the edentulous and
G. R. Barker,
BSc,
MSc,
patient
uiri
FDSRCS,
EDb
University
Dental
Medicine,
Dental
Hospital School,
of Manchester, Cardiff,
Manchester,
U.K.,
and University
of Wales
College
of
U.K.
A variety of problems faces the prosthodontist attempting reconstruction of maxillary defects. This article reviews developments in materials and techniques of obturator prosthesis design for patients experiencing maxillectomy. The size of the maxillectomy defect is one of the main factors governing the prognosis for treatment. Many patients require special prosthodontic techniques. However, rontine attention to extension of the prosthesis and balanced occlusion is essential. Obtaining satisfactory retention and stability in the definitive obturator prosthesis can be ehmive. Resilient denture base materials are extremely useful in retaining the prosthesis, which obturates small defects. However, the flexibility of these materials makes them unsuitable in large maxillectomy cavities because of the deformation that occurs during mastication. Alternative forms of retention, eg., osseointegrated implants and sectional prostheses retained by magnets, are discussed. (JPROSTHET DENT 1992;67:22%7.)
ith improved detection and survival rates following head and neck ablative surgery, patients are now treated in increasing numbers for prosthetic rehabilitation. This article reviews the principles of management of maxillectomy procedures and illustrates prosthodontic problems. Reconstruction begins with biologically inert materials draped with a split skin or dermal graft. To support the packing, an acrylic resin base is fabricated to replace the hard palate. The pack is formed from composition impression compound and/or ribbon gauze impregnated with Whitehead’s varnish (a blend of tolu balsam, iodoform, and storax). The acrylic resin base is retained with perialveolar wiring on the nonoperated side and a zygomatic buttress or zygomatico-temporal wiring on the operated side. Other methods of stabilizing the immediate surgical obturator prosthesis have been described in the literature; e.g., piriform aperture wiring, Kirschner wires, screw fixation,’ or sectional prostheses.2, 3 Where large total maxillectomy cavities are present, composition impression compound is too heavy. Radcliffe et al4 described an immediate obturator prosthesis of silicone elastomer (Silastic, Dow Chemical Co., Dow Plastics, Midland, Mich.) foam, which was attached to an acrylic resin base. The prosthesis was light, and by engaging suitable undercut regions was retentive and avoided the use of accessory wires. Two to 3 weeks after the initial surgery, the obturator prosthesis is removed under general anesthesia to assess aLecturer, Restorative Dentistry, University Dental Hospital of Manchester. bMedical Director, Astra Pharmaceuticals, Limited, Kings Langly, U.K.
10/l/31361
THE
JOURNAL
OF
PROSTHETIC
DENTISTRY
healing of the cavity. If healing is progressing satisfactorily, the cavity is lightly repacked. Depending on the histopathologist’s report from the previous operation and the local appearance, further surgery may be undertaken to remove any neoplastic tissue. At about 6 to 8 weeks the cavity is fully granulated, all packing is removed, and impressions for the first tooth bearing obturator prosthesis can be started.
PROSTHETIC
REHABILITATION
A firmly retained prosthesis can provide the patient with psychologic support during the difficult period after maxillectomy. ru’aturally, patients require constant encouragement and usually develop good muscular control of their prostheses. The quality of retention of the denture is dependent on the following factors, in addition to the development of good muscular control: (1) the size of the surgical cavity, (2) the availability of tissue undercut around the cavity,s and (3) indirect and direct retention provided by any remaining teeth.6 These three factors are dependent on surgical considerations. Current surgical practice should involve close cooperation with a prosthodontist. The smaller the tumor, the less radical the maxillectomy and the easier will be the prosthetic rehabilitation. If the tumor extends into the orbital cavity, the orbital contents and possibly the sphenoidal, ethmoidal, and frontal sinuses will need to be cleared of tumor tissue to include a safe margin of normal tissue. The maxillary tuberosities should be left if possible, as they increase the support of the obturator prosthesis7 Careful surgical planning will avoid malpositioned fibrous attachments that can cause di.scomfort and prosthesis displacement. The main retentive regions are the fibrous tissue scar bands in the buccal sul223
DEVLIN
maxillectomy acrylic
BARKER
cavity
button
molloolast
fibrous
AND
obturator
scar
Fig.
1. Silicone
obturator
prosthesis
retained
using small rare earth magnet.
Fig. 3. Silicone Fig. 2. Cobalt-samarium magnet must be retained mechanically in silicone obturator prosthesis. Flexible silicone is inserted by patient. Conventional denture, which contams a magnetic keeper, is magnetically retained.
cus, the rolled edge of the palatal remnants, and the base of the nasal mucosa of the nasal septum. The nares may not provide adequate retention for the definitive obturator prosthesis if the bone support has been removed.
THE DEFINITIVE ROSTHESIS
OBTURATOR
Development of silicone and rubber base materials has allowed the dentist to record deeper tissue undercuts without discomfort to the patient, damage to the remaining tissue, or tearing of the impression. Some techniques are useful in treating the small defect, others are better employed with the more extensive maxillary defect.
Small maxillary
defects
Bennington and Clifford8 and Davenport9 techniques that involve injecting impression
224
described material
obturator is trimmed so that it can be atraumatically inserted and worn by the patient, but is adequately retentive.
through the impression tray to precisely record the cavity tissue undercut. Light, flexible, silicone extensions are retentive because they engage the defect undercut.lO Davenport9 described the procedures involved in constructing a silicone obturator prosthesis for small maxillary defects that attached to a conventional acrylic resin denture by means of a cobalt-samarium magnet (Fig. 1). The magnet must be retained in the prosthesis with an acrylic resin button that is mechanically held in place (Fig. 2). The obturator prosthesis is flexible and can engage the available soft tissue undercut on placement (Fig. 3). The use of magnets to stabilize maxiliofacial prostheses was described by Nadeaull nearly 40 years ago. However, the introduction of rare earth magnets have improved the problems of corrosion and excessive bulk. Retention of the silicone prosthesis is usually excellent when adequate tissue undercuts remain around the soft palate and on the buccal aspect. The seal on the operated side may be lost during function because of flexing of the silicone as a masticatory load is applied, which allows the ingress of food and liquids. Certain other problems are commonly encountered
FEBRUARY
1992
VOLUME
61
NUIMMBER
2
OBTURATOR
PROSTHESES
AND
MAXILLECTOMY
Fig. 4. Large hollow obturator prostheses have advantage that they are lighter than solid prostheses.
with silicone prostheses. Radiotherapy can result in fibrosis, facial disfigurement, and a tendency to closing of the maxillectomy defect. Heat-cured silicone is difficult to adjust to these changes without producing a relatively rough surface, which is difficult to clean and may support fungal growth, especially Candida albicans. In addition, movement of the prosthesis during function may traumatize the supporting mucosa, particularly if the tissue has been previously irradiated12 and lubrication has been reduced by irradiation of the salivary glands. The surfaces in the maxillectomy cavity that retain the prosthesis should be keratinized to resist prosthesis friction. This is the function of the split-thickness skin graft.13 Successful prosthetic rehabilitation may be more likely where the remaining tissues offer possibilities for excellent prosthesis retention and stability. Guiding planes on remaining teeth, parallel with the defect walls, may prevent rotation of the prosthesis out of the maxillectomy cavity. Crowns with splinting of abutment teeth may be necessary. l4 Extension of the obturator prosthesis onto the nasopharyngeal surface of the soft palate will also improve retention. Therefore soft palate surgery should leave a rim of tissue, if possible.5 Block et all5 described hydroxyapatite-coated implants that were inserted in the residual zygoma to retain a palatally projecting bar and two magnet keepers. Magnets were placed within the maxillary obturator prosthesis.
Large
maxillary
defect
The retention of large obturator prostheses can be difficult, especially if they are solid and heavy, rather than hollow and light (Fig. 4). The dentist is advised to further increase retention by extending the lateral border of the prosthesis as high into the defect as possible to minimize the vertical displacement under load.16 In practice several problems can occur. 1. It can be difficult to make an impression of the full extent of the defect because of trismus, which prevents in-
THE
JOIIRNAL
OF PROSTHETIC
DENTISTRY
Fig. 5. Sectional impression technique can be used where full depth of undercut must be recorded and a special tray loaded with impression material cannot be inserted.
Fig. 6. In this sectional impression technique, different sections of silicone putty are removed from mouth and reassembled. Accurate impression of fuil depth of the defect has been obtained. sertion of the impression material and special tray into the mouth. Adismani7 pioneered the use of sectional impressions in the construction of obturator prostheses. A sectional impression technique is recommended, which involves placing successive layers of silicone putty into the defect (Fig. 5). These layers are grooved and covered with petroleum jelly in such a way that they can later be reassembled outside the mouth (Fig. 6). The sectional impression of the defect is completed by smoothing silicone putty over the entrance to the defect to form a palatal shape. An impression is made of the silicone covering the entrance to the defect and the residual palatal tissues using a special tray and medium-bodied silicone wash material. The silicone putty can then be located on the special tray outside the mouth, and then cast in dental stone. 2. The path of insertion of the obturator prosthesis as it enters the defect may conflict with engagement of the undercut around the remainder of the alveolar ridge. Resilient denture base materials (such as Molloplast B, Regneri Gmbh & Co., Kamsruhe, Germany) may be used at the border of the denture to engage the undercut at the base of the sulcus. This material can also be used in extensions to the
225
Fig. 7. Resilient silicone extensions to denture increase denture retention. Amount of undercut they engage must be carefully assessed, as tissues may be delicate and easily traumatized.
prosthesis to engage undercuts and aid retentionIs (Fig. 7). Small, powerful cobalt-samarium magnets have been described for the retention of large maxillofacial prostheses.rg The prosthesis is composed of several sections that are retained together by magnets when in place in the defect. Each section has a different path of insertion, which provides the assembled prosthesis with resistance to displacement. The insertion of osseointegrated fixtures in the residual maxillary alveolar ridge has been recently described for the retention of prostheses following partial maxillectomy.20 The osseointegrated fixtures were linked by a soldered bar, and engaged by a clip bar attachment in the denture. Many surgeons are reluctant to introduce bone-anchored titanium implants into the surgical site, as infection may result, especially if radiation has been used. The vascular supply to irradiated bone is reduced, which results in an impaired healing capacity, and the bone becomes prone to osteoradionecrosis. Schweigerzl irradiated 60 mandibles of beagle dogs and found osseointegration was achieved in only half of the irradiated specimens. Jacobsson et a1.22demonstrated the ability of bone to undergo osseointegration with titanium implants in man, even after high doses of radiation. No implants were removed because of soft tissue or bone infection. This study reported on nine patients. In a large Swedish multicenter study, Albrektsson et a1.23 reported the insertion of 13 successful implants and three failures in irradiated maxillary bone over 1 to 5 years. Their success rate (81.25%) compared favorably with a success rate of 84.9 % in 106 maxillary implants inserted in nonirradiated bone and observed 5 to 7 years. However, Albrektsson et al.23 observed that the number of maxillary implants inserted in irradiated bone in their study was relatively small, and the observation period was limited to 1 to 5 years. A further international, multicenter study reported 100% success over 1 to 5 years with 10 implants inserted in the irradiated maxillae.24 Implant insertion in
226
the maxillae may not be absolutely contraindicated by previous irradiation. However, further data are required so that the effects on implant success of long-term functional loading, radiation dose, and time interval prior to implant insertion can be determined. Surgery may greatly simplify the prosthetic reconstruction following maxillary resection. Vascularized bone grafts are less dependent on the limitations imposed by the vascularity of the recipient site and have some resistance to infection. Riediger25 used a free osteomyocutaneous groin flap in reconstruction in five patients requiring maxillary resection. Bone reconstruction allowed the future insertion of implants into the graft and by retaining bone vitality, this method may prevent resorption. By comparison, nonvascularized bone grafts inevitably undergo some resorption. With large defects, vascularized bone allografts reduce the surgical trauma to the host but unleash the host’s immune response, leading to graft rejection. The toxicity of present immunosuppressive therapy prevents the use of these grafts. CONCLUSION Treatment options for patients requiring a partial maxillectomy and obturator prosthesis include the use of magnets, hollow obturator prostheses, and resilient silicone materials as purely prosthodontic treatment solutions. Implants and reconstructive surgery may become increasingly important treatment options in the future, but are often complicated by the age of the patients and by radiotherapy. REFERENCES 1. 2. 3. 4.
5. 6.
7.
8. 9.
10. 11. 12. 13.
DeMarino DP,
Maws MD. Anchoring the pal&al prosthesis after maxillectomy. Laryngoscope 1988;98:791-2. Schaitkin B, Hessan H, Strauss M. The use of screws for maxillary denture fixation. Laryngoscope 1989;99:660-1. Welfare RD, Davis DM. Immediate obturation for partial maxillectomy. Br J Oral Maxillofac Surg 1988;26:255-7. Radcliffe GJ, Mady S, Bur R, Cheesman AD, Wilson D. A new immediate temporary lightweight obturator for maxillectomy cavities. Br J Oral Maxillofac Surg 1984;22:50-63. Desjardins RP. Obturator prosthesis design for acquired maxillary defects.J PROSTHET DENT 1978;39:424-35. Parr CR, Tharp GE,Rahn AO. Prosthodontic principles in the framework design of maxillary obturator prostheses. J PROSTHET DENT 1989: 62205.12. Rahn AO, Goldman BM, Parr GR. Prosthodontic principles in surgical planning for maxillary and mandibular resection patients. J PROSTHET DENT 1979;42:429-33. Bennington IC, Clifford T. An injection impression technique for palatal defects. J PROSTHET DENT 1982;47:414-8. Davenport JC. Clinical and laboratory procedures for the production of a retentive silicone rubber obturator for the maxillectomy patient. Br J Oral Maxillofac Surg 1984;22:378-86. Hahn GW. A comfortable silicone bulb obturator with or without dentures.J PROSTHET D~~~1972;28:313-7. Nadeau J. Maxillofacial prosthesis with magnet stabilizers. J PROSTHET DENT 1955;6:114-9. Udagama A, King GE. Mechanically retained facial prostheses: helpful or harmful? J PROSTHET DENT 1983;49:85-6. Marunick MJ, Harrison R, Beumer J. Prosthodontic rehabilitation of midfacial defects. J PROSTHET DENT 1985;54:553-60.
FEBRUARY1992
VOLUME67
NUMBER2
OBTURATOR
PROSTHESES
AND
MAXILLECTOMY
14. Adisman IK. Prosthesis serviceability for acquired jaw defects. Dent Clin North Am 1990;34:265-84. 15. Block MS, Guerra LR, Kent JN, Finger IM. Hemimaxillectomy prosthesis stabilization with hydroxlapatite-coated implants: a case report. Int J Oral Maxillofac Implant 1987;2:111-3. 16. Brown KE. Peripheral consideration in improving obturator retention. J PROSTHET DENT 1968;203176-81. 17. Ad&man IX. Removable partial dentures for jaw defects of the maxilla and mandible. Dent Clin North Am 1962:849-70. 18. Bennington IC. Post surgical prosthodontics: clinical notes. 3 Oral Rehabil 1983;10:31-40. 19. Sasaki H, Kinouchi Y, Tsutsui H, Yoshida Y, Karv M, Ushita T. Sectional prostheses connected by samarium-cobalt magnets. J PROSTHET DENT
1984;52:556-60.
20. Pare1 SM, Branemark PI, Jansson T. Osseointegration in maxillofacial prosthetics. Part 1. Intraoral applications. J PROSTHET DENT 1986; 55:490-4.
21. Schweiger PROSTHET
THE
JOURNAL
JW.
Titanium
DENT
1989:62:201-5.
OF
PROSTHETIC
implants
in irradiated
DENTISTRY
dog mandibles.
J
22. Jacobsson M, Tjellstrom A, Thomsen P; Albrekmson T, Turesson 1. Integration of titanium implants in irradiated bone. Histologic and clinical study. Ann Otol Rhino1 Laryngol 1988;97:337-40. 23. Albrektsson T, Dahl E, Enbom L, et al. Osseointegrated oral implants. A Swedish multicenter study of 8139 consecutively inserted Nobelpharma implants. J Periodontol 1988;59:287-96. 24. Albrektsson T. A multicenter report on osseointegrated oral implants. J PROSTHET DENT 1988;60:75-84. 25. Riediger D. Restoration of masticatory function by microsurgically revascularized iliac crest bone grafts using enosseous implants. Plast Reconstr Surg 1988;81:861-75. Reprint requests to: DR. H. DEVLIN UNIVERSITY DENTAL HOSPITAL HIGHER CAMBRIDGE ST. MANCHESTER Ml5 6FH UNITED KINGDOM
OF MANCHESTER
227
PhD,
MSc,
BSc,
BDSa
of the edentulous and
G. R. Barker,
BSc,
MSc,
patient
uiri
FDSRCS,
EDb
University
Dental
Medicine,
Dental
Hospital School,
of Manchester, Cardiff,
Manchester,
U.K.,
and University
of Wales
College
of
U.K.
A variety of problems faces the prosthodontist attempting reconstruction of maxillary defects. This article reviews developments in materials and techniques of obturator prosthesis design for patients experiencing maxillectomy. The size of the maxillectomy defect is one of the main factors governing the prognosis for treatment. Many patients require special prosthodontic techniques. However, rontine attention to extension of the prosthesis and balanced occlusion is essential. Obtaining satisfactory retention and stability in the definitive obturator prosthesis can be ehmive. Resilient denture base materials are extremely useful in retaining the prosthesis, which obturates small defects. However, the flexibility of these materials makes them unsuitable in large maxillectomy cavities because of the deformation that occurs during mastication. Alternative forms of retention, eg., osseointegrated implants and sectional prostheses retained by magnets, are discussed. (JPROSTHET DENT 1992;67:22%7.)
ith improved detection and survival rates following head and neck ablative surgery, patients are now treated in increasing numbers for prosthetic rehabilitation. This article reviews the principles of management of maxillectomy procedures and illustrates prosthodontic problems. Reconstruction begins with biologically inert materials draped with a split skin or dermal graft. To support the packing, an acrylic resin base is fabricated to replace the hard palate. The pack is formed from composition impression compound and/or ribbon gauze impregnated with Whitehead’s varnish (a blend of tolu balsam, iodoform, and storax). The acrylic resin base is retained with perialveolar wiring on the nonoperated side and a zygomatic buttress or zygomatico-temporal wiring on the operated side. Other methods of stabilizing the immediate surgical obturator prosthesis have been described in the literature; e.g., piriform aperture wiring, Kirschner wires, screw fixation,’ or sectional prostheses.2, 3 Where large total maxillectomy cavities are present, composition impression compound is too heavy. Radcliffe et al4 described an immediate obturator prosthesis of silicone elastomer (Silastic, Dow Chemical Co., Dow Plastics, Midland, Mich.) foam, which was attached to an acrylic resin base. The prosthesis was light, and by engaging suitable undercut regions was retentive and avoided the use of accessory wires. Two to 3 weeks after the initial surgery, the obturator prosthesis is removed under general anesthesia to assess aLecturer, Restorative Dentistry, University Dental Hospital of Manchester. bMedical Director, Astra Pharmaceuticals, Limited, Kings Langly, U.K.
10/l/31361
THE
JOURNAL
OF
PROSTHETIC
DENTISTRY
healing of the cavity. If healing is progressing satisfactorily, the cavity is lightly repacked. Depending on the histopathologist’s report from the previous operation and the local appearance, further surgery may be undertaken to remove any neoplastic tissue. At about 6 to 8 weeks the cavity is fully granulated, all packing is removed, and impressions for the first tooth bearing obturator prosthesis can be started.
PROSTHETIC
REHABILITATION
A firmly retained prosthesis can provide the patient with psychologic support during the difficult period after maxillectomy. ru’aturally, patients require constant encouragement and usually develop good muscular control of their prostheses. The quality of retention of the denture is dependent on the following factors, in addition to the development of good muscular control: (1) the size of the surgical cavity, (2) the availability of tissue undercut around the cavity,s and (3) indirect and direct retention provided by any remaining teeth.6 These three factors are dependent on surgical considerations. Current surgical practice should involve close cooperation with a prosthodontist. The smaller the tumor, the less radical the maxillectomy and the easier will be the prosthetic rehabilitation. If the tumor extends into the orbital cavity, the orbital contents and possibly the sphenoidal, ethmoidal, and frontal sinuses will need to be cleared of tumor tissue to include a safe margin of normal tissue. The maxillary tuberosities should be left if possible, as they increase the support of the obturator prosthesis7 Careful surgical planning will avoid malpositioned fibrous attachments that can cause di.scomfort and prosthesis displacement. The main retentive regions are the fibrous tissue scar bands in the buccal sul223
DEVLIN
maxillectomy acrylic
BARKER
cavity
button
molloolast
fibrous
AND
obturator
scar
Fig.
1. Silicone
obturator
prosthesis
retained
using small rare earth magnet.
Fig. 3. Silicone Fig. 2. Cobalt-samarium magnet must be retained mechanically in silicone obturator prosthesis. Flexible silicone is inserted by patient. Conventional denture, which contams a magnetic keeper, is magnetically retained.
cus, the rolled edge of the palatal remnants, and the base of the nasal mucosa of the nasal septum. The nares may not provide adequate retention for the definitive obturator prosthesis if the bone support has been removed.
THE DEFINITIVE ROSTHESIS
OBTURATOR
Development of silicone and rubber base materials has allowed the dentist to record deeper tissue undercuts without discomfort to the patient, damage to the remaining tissue, or tearing of the impression. Some techniques are useful in treating the small defect, others are better employed with the more extensive maxillary defect.
Small maxillary
defects
Bennington and Clifford8 and Davenport9 techniques that involve injecting impression
224
described material
obturator is trimmed so that it can be atraumatically inserted and worn by the patient, but is adequately retentive.
through the impression tray to precisely record the cavity tissue undercut. Light, flexible, silicone extensions are retentive because they engage the defect undercut.lO Davenport9 described the procedures involved in constructing a silicone obturator prosthesis for small maxillary defects that attached to a conventional acrylic resin denture by means of a cobalt-samarium magnet (Fig. 1). The magnet must be retained in the prosthesis with an acrylic resin button that is mechanically held in place (Fig. 2). The obturator prosthesis is flexible and can engage the available soft tissue undercut on placement (Fig. 3). The use of magnets to stabilize maxiliofacial prostheses was described by Nadeaull nearly 40 years ago. However, the introduction of rare earth magnets have improved the problems of corrosion and excessive bulk. Retention of the silicone prosthesis is usually excellent when adequate tissue undercuts remain around the soft palate and on the buccal aspect. The seal on the operated side may be lost during function because of flexing of the silicone as a masticatory load is applied, which allows the ingress of food and liquids. Certain other problems are commonly encountered
FEBRUARY
1992
VOLUME
61
NUIMMBER
2
OBTURATOR
PROSTHESES
AND
MAXILLECTOMY
Fig. 4. Large hollow obturator prostheses have advantage that they are lighter than solid prostheses.
with silicone prostheses. Radiotherapy can result in fibrosis, facial disfigurement, and a tendency to closing of the maxillectomy defect. Heat-cured silicone is difficult to adjust to these changes without producing a relatively rough surface, which is difficult to clean and may support fungal growth, especially Candida albicans. In addition, movement of the prosthesis during function may traumatize the supporting mucosa, particularly if the tissue has been previously irradiated12 and lubrication has been reduced by irradiation of the salivary glands. The surfaces in the maxillectomy cavity that retain the prosthesis should be keratinized to resist prosthesis friction. This is the function of the split-thickness skin graft.13 Successful prosthetic rehabilitation may be more likely where the remaining tissues offer possibilities for excellent prosthesis retention and stability. Guiding planes on remaining teeth, parallel with the defect walls, may prevent rotation of the prosthesis out of the maxillectomy cavity. Crowns with splinting of abutment teeth may be necessary. l4 Extension of the obturator prosthesis onto the nasopharyngeal surface of the soft palate will also improve retention. Therefore soft palate surgery should leave a rim of tissue, if possible.5 Block et all5 described hydroxyapatite-coated implants that were inserted in the residual zygoma to retain a palatally projecting bar and two magnet keepers. Magnets were placed within the maxillary obturator prosthesis.
Large
maxillary
defect
The retention of large obturator prostheses can be difficult, especially if they are solid and heavy, rather than hollow and light (Fig. 4). The dentist is advised to further increase retention by extending the lateral border of the prosthesis as high into the defect as possible to minimize the vertical displacement under load.16 In practice several problems can occur. 1. It can be difficult to make an impression of the full extent of the defect because of trismus, which prevents in-
THE
JOIIRNAL
OF PROSTHETIC
DENTISTRY
Fig. 5. Sectional impression technique can be used where full depth of undercut must be recorded and a special tray loaded with impression material cannot be inserted.
Fig. 6. In this sectional impression technique, different sections of silicone putty are removed from mouth and reassembled. Accurate impression of fuil depth of the defect has been obtained. sertion of the impression material and special tray into the mouth. Adismani7 pioneered the use of sectional impressions in the construction of obturator prostheses. A sectional impression technique is recommended, which involves placing successive layers of silicone putty into the defect (Fig. 5). These layers are grooved and covered with petroleum jelly in such a way that they can later be reassembled outside the mouth (Fig. 6). The sectional impression of the defect is completed by smoothing silicone putty over the entrance to the defect to form a palatal shape. An impression is made of the silicone covering the entrance to the defect and the residual palatal tissues using a special tray and medium-bodied silicone wash material. The silicone putty can then be located on the special tray outside the mouth, and then cast in dental stone. 2. The path of insertion of the obturator prosthesis as it enters the defect may conflict with engagement of the undercut around the remainder of the alveolar ridge. Resilient denture base materials (such as Molloplast B, Regneri Gmbh & Co., Kamsruhe, Germany) may be used at the border of the denture to engage the undercut at the base of the sulcus. This material can also be used in extensions to the
225
Fig. 7. Resilient silicone extensions to denture increase denture retention. Amount of undercut they engage must be carefully assessed, as tissues may be delicate and easily traumatized.
prosthesis to engage undercuts and aid retentionIs (Fig. 7). Small, powerful cobalt-samarium magnets have been described for the retention of large maxillofacial prostheses.rg The prosthesis is composed of several sections that are retained together by magnets when in place in the defect. Each section has a different path of insertion, which provides the assembled prosthesis with resistance to displacement. The insertion of osseointegrated fixtures in the residual maxillary alveolar ridge has been recently described for the retention of prostheses following partial maxillectomy.20 The osseointegrated fixtures were linked by a soldered bar, and engaged by a clip bar attachment in the denture. Many surgeons are reluctant to introduce bone-anchored titanium implants into the surgical site, as infection may result, especially if radiation has been used. The vascular supply to irradiated bone is reduced, which results in an impaired healing capacity, and the bone becomes prone to osteoradionecrosis. Schweigerzl irradiated 60 mandibles of beagle dogs and found osseointegration was achieved in only half of the irradiated specimens. Jacobsson et a1.22demonstrated the ability of bone to undergo osseointegration with titanium implants in man, even after high doses of radiation. No implants were removed because of soft tissue or bone infection. This study reported on nine patients. In a large Swedish multicenter study, Albrektsson et a1.23 reported the insertion of 13 successful implants and three failures in irradiated maxillary bone over 1 to 5 years. Their success rate (81.25%) compared favorably with a success rate of 84.9 % in 106 maxillary implants inserted in nonirradiated bone and observed 5 to 7 years. However, Albrektsson et al.23 observed that the number of maxillary implants inserted in irradiated bone in their study was relatively small, and the observation period was limited to 1 to 5 years. A further international, multicenter study reported 100% success over 1 to 5 years with 10 implants inserted in the irradiated maxillae.24 Implant insertion in
226
the maxillae may not be absolutely contraindicated by previous irradiation. However, further data are required so that the effects on implant success of long-term functional loading, radiation dose, and time interval prior to implant insertion can be determined. Surgery may greatly simplify the prosthetic reconstruction following maxillary resection. Vascularized bone grafts are less dependent on the limitations imposed by the vascularity of the recipient site and have some resistance to infection. Riediger25 used a free osteomyocutaneous groin flap in reconstruction in five patients requiring maxillary resection. Bone reconstruction allowed the future insertion of implants into the graft and by retaining bone vitality, this method may prevent resorption. By comparison, nonvascularized bone grafts inevitably undergo some resorption. With large defects, vascularized bone allografts reduce the surgical trauma to the host but unleash the host’s immune response, leading to graft rejection. The toxicity of present immunosuppressive therapy prevents the use of these grafts. CONCLUSION Treatment options for patients requiring a partial maxillectomy and obturator prosthesis include the use of magnets, hollow obturator prostheses, and resilient silicone materials as purely prosthodontic treatment solutions. Implants and reconstructive surgery may become increasingly important treatment options in the future, but are often complicated by the age of the patients and by radiotherapy. REFERENCES 1. 2. 3. 4.
5. 6.
7.
8. 9.
10. 11. 12. 13.
DeMarino DP,
Maws MD. Anchoring the pal&al prosthesis after maxillectomy. Laryngoscope 1988;98:791-2. Schaitkin B, Hessan H, Strauss M. The use of screws for maxillary denture fixation. Laryngoscope 1989;99:660-1. Welfare RD, Davis DM. Immediate obturation for partial maxillectomy. Br J Oral Maxillofac Surg 1988;26:255-7. Radcliffe GJ, Mady S, Bur R, Cheesman AD, Wilson D. A new immediate temporary lightweight obturator for maxillectomy cavities. Br J Oral Maxillofac Surg 1984;22:50-63. Desjardins RP. Obturator prosthesis design for acquired maxillary defects.J PROSTHET DENT 1978;39:424-35. Parr CR, Tharp GE,Rahn AO. Prosthodontic principles in the framework design of maxillary obturator prostheses. J PROSTHET DENT 1989: 62205.12. Rahn AO, Goldman BM, Parr GR. Prosthodontic principles in surgical planning for maxillary and mandibular resection patients. J PROSTHET DENT 1979;42:429-33. Bennington IC, Clifford T. An injection impression technique for palatal defects. J PROSTHET DENT 1982;47:414-8. Davenport JC. Clinical and laboratory procedures for the production of a retentive silicone rubber obturator for the maxillectomy patient. Br J Oral Maxillofac Surg 1984;22:378-86. Hahn GW. A comfortable silicone bulb obturator with or without dentures.J PROSTHET D~~~1972;28:313-7. Nadeau J. Maxillofacial prosthesis with magnet stabilizers. J PROSTHET DENT 1955;6:114-9. Udagama A, King GE. Mechanically retained facial prostheses: helpful or harmful? J PROSTHET DENT 1983;49:85-6. Marunick MJ, Harrison R, Beumer J. Prosthodontic rehabilitation of midfacial defects. J PROSTHET DENT 1985;54:553-60.
FEBRUARY1992
VOLUME67
NUMBER2
OBTURATOR
PROSTHESES
AND
MAXILLECTOMY
14. Adisman IK. Prosthesis serviceability for acquired jaw defects. Dent Clin North Am 1990;34:265-84. 15. Block MS, Guerra LR, Kent JN, Finger IM. Hemimaxillectomy prosthesis stabilization with hydroxlapatite-coated implants: a case report. Int J Oral Maxillofac Implant 1987;2:111-3. 16. Brown KE. Peripheral consideration in improving obturator retention. J PROSTHET DENT 1968;203176-81. 17. Ad&man IX. Removable partial dentures for jaw defects of the maxilla and mandible. Dent Clin North Am 1962:849-70. 18. Bennington IC. Post surgical prosthodontics: clinical notes. 3 Oral Rehabil 1983;10:31-40. 19. Sasaki H, Kinouchi Y, Tsutsui H, Yoshida Y, Karv M, Ushita T. Sectional prostheses connected by samarium-cobalt magnets. J PROSTHET DENT
1984;52:556-60.
20. Pare1 SM, Branemark PI, Jansson T. Osseointegration in maxillofacial prosthetics. Part 1. Intraoral applications. J PROSTHET DENT 1986; 55:490-4.
21. Schweiger PROSTHET
THE
JOURNAL
JW.
Titanium
DENT
1989:62:201-5.
OF
PROSTHETIC
implants
in irradiated
DENTISTRY
dog mandibles.
J
22. Jacobsson M, Tjellstrom A, Thomsen P; Albrekmson T, Turesson 1. Integration of titanium implants in irradiated bone. Histologic and clinical study. Ann Otol Rhino1 Laryngol 1988;97:337-40. 23. Albrektsson T, Dahl E, Enbom L, et al. Osseointegrated oral implants. A Swedish multicenter study of 8139 consecutively inserted Nobelpharma implants. J Periodontol 1988;59:287-96. 24. Albrektsson T. A multicenter report on osseointegrated oral implants. J PROSTHET DENT 1988;60:75-84. 25. Riediger D. Restoration of masticatory function by microsurgically revascularized iliac crest bone grafts using enosseous implants. Plast Reconstr Surg 1988;81:861-75. Reprint requests to: DR. H. DEVLIN UNIVERSITY DENTAL HOSPITAL HIGHER CAMBRIDGE ST. MANCHESTER Ml5 6FH UNITED KINGDOM
OF MANCHESTER
227
