- Email: [email protected]
Orofacial rehabilitation with zygomatic implants: CAD-CAM bar and magnets for patients with nasal cancer after rhinectomy and partial maxillectomy
CLINICAL REPORT
Orofacial rehabilitation with zygomatic implants: CAD-CAM bar and magnets for patients with nasal cancer after rhinectomy and partial maxillectomy Elizabeth King, BDS(Hons), MSc,a Carl Abbott, BSc(Hons)(Eng),b Lawrence Dovgalski, BSc(Hons),c and James Owens, BDS, MScd Malignancy of the nasal ABSTRACT septum or vestibule is rare Nasal carcinoma extending into the premaxilla requires radical surgical excision including rhineaffecting 0.3 per 100 000 of the ctomy and partial maxillectomy. Rehabilitation is complex and involves the use of removable 1 population. The risk factors prostheses. Three patients treated with zygomatic implants and custom-milled bars to retain an are poorly understood, but a obturator and nasal prosthesis are presented. (J Prosthet Dent 2016;-:---) high number of patients are smokers.2 The most common signs and symptoms after radiotherapy, and the esthetic outcome is unpreinclude nasal obstruction, epistaxis, and nasal masses.2 dictable and often poorer than a nasal prosthesis.3,6 For Squamous cell carcinoma (SCC) is the most common nasal rehabilitation, a nasal prosthesis is often better histologic type, followed by adenocarcinoma.2 Maligthan reconstruction as it allows easier postoperative nancies can invade the nasal fossa, premaxilla, upper lip, monitoring and a more predictable esthetic outcome.7 3 or nasal crest. If metastasis occurs, the lung is the most Nasal prostheses are most commonly made of silicone common site followed by the brain, bone, and skin.3 and traditionally rely on tissue undercuts and adhesive Treatment depends on the extent of disease and for retention. More recently, zygomatic implants have includes surgical excision and radiotherapy. Surgery is been shown to provide successful and predictable often the modality of choice, and if bone is involved, retention of nasal prostheses.8,9 Obturators that restore 2,4 rhinectomy is indicated. Overall 5-year survival rates the maxilla and associated dentition are frequently used are approximately 58%,3 with a high recurrence rate of for the rehabilitation of maxillary defects and also benefit 43% occurring after a mean of 9.4 months.5 from osseointegrated implants for improved retention.10 Because of the nature of surgical treatment, patients Anecdotally, patients who require restoration of orofacial with nasal malignancy can be left with substantial defects by using both obturators and nasal prostheses orofacial defects. In rare situations, nasal malignancies experience problems with loss of retention of the locally invade the maxilla, and thus treatment nasal prosthesis because of movement of the obturator involves partial maxillectomy along with rhinectomy. during function when adequate retention is not Rehabilitation includes flap reconstruction or the provided. This clinical report describes the prosthetic provision of a maxillofacial (nasal or oral) prosthesis. rehabilitation of 3 patients who underwent rhinectomy Surgical reconstruction of small defects and even comand partial maxillectomy for the treatment of nasal plete reconstruction of the nose are possibilities. malignancy, using zygomatic implant-supported nasal However, surgical morbidity is increased, particularly and oral prostheses.
a
Specialty Registrar, Restorative Dentistry, Moriston Hospital Restorative Department, Swansea, Wales. Lead Restorative Technologist, Moriston Hospital Restorative Department, Swansea, Wales. c Maxillofacial Prosthesist, Moriston Hospital Restorative Department, Swansea, Wales. d Consultant in Restorative Dentistry, Moriston Hospital Restorative Department, Swansea, Wales. b
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Her social history included smoking 10 cigarettes a day for 20 years and alcohol consumption of 7 units per week. She initially underwent partial rhinectomy, followed by radiotherapy of 60 Gy in 30 fractions. Histopathology revealed residual SCC, and more radical surgery, including rhinectomy, partial anterior maxillectomy, and selective neck dissection was undertaken. During the second surgical procedure, bilateral zygomatic implants were placed for the magnetic retention of a complete nasal prosthesis, and a surgical obturator was provided.
Figure 1. Surgical stent in situ to guide placement of zygomatic implants after rhinectomy and partial maxillectomy (blue arrows indicate approximate position of planned zygomatic implant position) (Patient 1).
CLINICAL REPORTS Patient 1 A 69-year-old man received a diagnosis of SCC of the nasal vestibule and floor of the nasal cavity in September 2013. His medical history included well-controlled hypertension. He had a smoking history of 5 cigarettes per day for 30 years and an alcohol intake of 28 to 35 units per week. He underwent rhinectomy, partial maxillectomy, and bilateral neck dissection. The upper lip skin and muscle was preserved. Bilateral zygomatic implants were placed at the time of surgery to provide magnetic retention of a complete nasal prosthesis, and a surgical obturator was provided. Histopathology revealed a completely excised, poorly differentiated SCC. Along with surgery, he received radiotherapy, 60 Gy in 30 fractions. Patient 2 In June 2013, SCC of the nasal septum was diagnosed in a 70-year-old woman. The cancer extended to the anterior maxilla. Her medical history included depression, chronic fatigue syndrome, and hyperlipidemia. Her social history included smoking 30 cigarettes per day for 30 years and an alcohol intake of 10 units per week. She underwent rhinectomy, partial maxillectomy, and bilateral neck dissection with preservation of the muscle and skin of the upper lip. Bilateral zygomatic implants were placed at the time of surgery to provide magnetic retention of a complete nasal prosthesis, and a surgical obturator was provided. Histopathology showed complete excision of poorly differentiated SCC. She received postoperative radiotherapy of 60 Gy in 30 fractions. Patient 3 Squamous cell carcinoma of the nasal septum was diagnosed in a 76-year-old woman in September 2012. THE JOURNAL OF PROSTHETIC DENTISTRY
Planning of obturator and nasal prosthesis retention For each patient, zygomatic implants were planned preoperatively to provide retention for a nasal prosthesis. Computed tomography scan data were used to plan the zygomatic implant position, and a surgical stent was made to use at the time of surgery to guide the zygomatic implant placement (Fig. 1). To simplify the orofacial rehabilitation process, it was decided that the zygomatic implants would also be used to retain the obturator prosthesis. Zygomatic implants emerging into the nasal defect were planned, as emergence into the oral cavity would limit their use for the obturator prosthesis only. Although placement of 4 zygomatic implants with both oral and nasal emergence would have been possible, this would have significantly increased surgical complexity and the risk of implant perforation. Alternative options included dental implant placement; however, placement in the anterior maxilla would require a composite free flap (bone and soft tissue), and placement in the posterior maxilla would require bilateral sinus lifts. Both of the surgical procedures would have significantly increased the surgical complexity, introduced further morbidity, and in the case of the free flap, introduced the need for a donor site. Therefore, use of the zygomatic implants for both the nasal prosthesis and obturator significantly simplified the rehabilitation process and reduced potential surgical complications. Definitive obturator construction In each situation, a definitive obturator was fabricated by a consultant in restorative dentistry and a dental laboratory technician. Maxillary and mandibular irreversible hydrocolloid impressions (Jeltrate; Dentsply Intl) were made in stock impression trays and poured with Type IV dental stone (Galaxy; Platres & Mineraux), and a maxillary custom-made impression tray was fabricated with light-polymerizing acrylic resin (Magilight; Schottlander). Maxillary impressions were then made with mediumbodied polyvinyl siloxane (Aquasil Ultra; Dentsply Intl) and poured in Type IV stone. The stone casts were duplicated with silicone (Z-Dupe; Henry Schein), and heat-polymerized acrylic resin baseplates covering the edentulous areas and obturating the maxillary defect were fabricated along with wax occlusion rims to record King et al
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2016
3
Figure 2. Magnet polymerized into position in obturator (Patient 1).
centric relation. The definitive tooth arrangement was developed on the baseplates and evaluated chairside, and the obturator was processed with acrylic resin (PalaXpress Ultra; Heraeus Kulzer Inc). After the computeraided design and computer-aided manufacturing (CAD-CAM) bar was evaluated for fit, an impression of the magnet in situ on the bar was made in the definitive obturator with medium-bodied polyvinyl siloxane (Occlufast Rock; Zhermack SpA). The magnet was then secured with autopolymerizing acrylic resin (Meadway Rapid Repair; MR. Dental) (Fig. 2). CAD-CAM bar construction After the definitive obturator was fitted, computed tomography data were evaluated to establish the osseointegrated hard tissue support provided by the zygomatic implants, and it was determined that the implants could be used to retain a CAD-CAM bar which would simultaneously retain both maxillofacial prostheses. For Patient 1, a polyvinyl siloxane impression (Aquasil Ultra; Dentsply Intl, Occlufast; Zhermack) of the implants and nasal defect was made with the definitive obturator in situ (Fig. 3). Type IV dental stone with 2 fixture replicas (Multi-unit Abutment Plus Replica; Nobel Biocare) was used to produce a definitive cast. Two nonengaging interim abutments (Abutment Replica Multi-Unit Brånemark System; Nobel Biocare) splinted with acrylic resin (GC Pattern Resin LS, GC America) were used to verify the accuracy of the impression and to ensure that the bar could be removed passively, considering the divergence of the implants (Fig. 4). The working cast was scanned (D800 Desktop Scanner; 3Shape), and data were imported into CAD software King et al
Figure 3. Silicone impression of zygomatic implants and nasal defect with obturator in situ (Patient 1).
Figure 4. Resin bar verification of zygomatic implants (Patient 1).
(3D Shape). The anatomy was assessed, and a crucifixshaped bar was designed to allow the horizontal splinting of the implants, incorporation of 2 magnets (Brånemark Mini Magnabutment; Technovent Ltd) for nasal prosthesis retention and incorporation of an attachment on the inferior aspect to retain a magnet (Brånemark Maxi Magnabutment; Technovent Ltd) for obturator retention (Fig. 5). An acrylic resin prototype of THE JOURNAL OF PROSTHETIC DENTISTRY
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Figure 5. CAD design of crucifix-shaped bar (Patient 1).
Figure 6. Crucifix-shaped bar in situ (Patient 1).
Figure 7. Example of T-shaped bar and obturator in situ (Patient 2).
the bar was fabricated. The bar was scanned and imported into the CAD software and sent to a milling company (Core 3D). The original design could not be fabricated as the milling unit would not accommodate the bar shape. This was overcome by redesigning the bar as 2 separate components, the crucifix-shaped bar and the magnet attachment. At the time, only cobaltchromium (Co-Cr) ingots were available; therefore, components were milled in Co-Cr and laser welded together. Two magnets were screwed into the bar, and 1 magnet was bonded into the cup-shaped attachment with dual-polymerizing composite resin (GC Gradia Composite; Terec Ltd). Figure 6 shows the crucifixshaped bar and obturator in situ. Patients 2 and 3 were treated in the same way patient 1 was; however, because of differences in anatomy, a THE JOURNAL OF PROSTHETIC DENTISTRY
Figure 8. Clinical outcome of obturator and nasal prosthesis retained by crucifix-shaped bar (Patient 1).
T-shaped bar (Fig. 7) was used instead of the crucifixshaped bar. Second, the milling company (Core 3D) had meanwhile obtained titanium milling ingots, and the bar components were milled in titanium. Nasal prosthesis fabrication Immediately after surgery, each patient was fitted with a nasal prosthesis attached to glasses. After soft tissue healing, a maxillofacial prosthetist fabricated a King et al
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2016
magnetically retained nasal prosthesis. In addition, a polymerized silicone impression with the bar and magnets in situ was made. Magnet analog fixtures were located on top of the impression magnets, and the impression was poured in gypsum (Crystacal R Plaster; SWIP Dental). A baseplate was fabricated with magnets and lightpolymerized resin (Triad Gel; Dentsply Intl) and evaluated to verify the accuracy of the cast. A wax prototype was fabricated from a preoperative computed tomography scan in CAD software (Freeform; Geomagics) to define the shape. A postoperative 3D surface scan (5-pod; 3DMD) was made, and the preoperative nose was adjusted to form a virtual nasal prosthesis. This was fabricated in stereolithography resin (PDR) and duplicated in wax (Anutex; Kemdent). Finally, the wax prototype was incorporated into the baseplate, and definitive carving was conducted at the clinical evaluation appointment. A gypsum cast of the wax prototype was produced and the wax was eliminated. The plaster cast was filled with silicone elastomer (Cosmesil HC2; Cosmesil), color matched, and polymerized. Figure 8 shows the definitive nasal prosthesis and obturator in situ.
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However, maxillofacial prostheses are not without caveats, and the potential complications of the prostheses described in this article include risk of zygomatic implant infection, irritation of supporting tissues, lifelong prosthesis maintenance, and significant patient cooperation for successful acclimatization. Specific difficulties described by the patients include degradation of nasal prosthesis, food leakage, dropping of posterior borders of the obturator, and generalized discomfort. A specific problem occurred for Patient 2; the titanium bar fractured at the welding spot soon after placement. Titanium is more difficult to weld than Co-Cr because of the need for a pure argon environment. The weld was repeated with no further problems. All 3 bars, obturators, and nasal prostheses fit well and were clinically stable and retentive. As of the present writing, 2 patients are functioning well with their prostheses, but 1 patient struggled psychologically with the appearance of the bar, so it was not fitted. Instead she has a magnetically retained nasal prosthesis with an obturator retained with soft tissue undercuts. REFERENCES
DISCUSSION Rehabilitation of patients after rhinectomy and partial maxillectomy requires a multidisciplinary team which includes maxillofacial surgeons, consultants in restorative dentistry, maxillofacial prosthetists, and appropriately trained dental laboratory technicians. Reconstructions should aim to improve esthetics and function in the immediate and long term, as well as allow examination of the tissues to monitor recurrence. The benefits of the maxillofacial prostheses described in this article include active retention of the obturator and nasal prosthesis with magnetic retention; improved ability to re-establish functions such as speech, mastication, and swallowing; improved ability to recover social life as soon as possible after surgery; ability to remove both prostheses to allow examination of tissues; ease of insertion and removal of prostheses by the patient; provision of upper lip support from the obturator, and avoidance of further invasive surgical procedures (such as dental implant placement, bone grafting) for obturator retention. Use of zygomatic implants for the concurrent retention of obturator and nasal prostheses significantly simplifies orofacial rehabilitation and removes the need of further invasive surgical procedures.
King et al
1. Acheson ED, Cowdell RH, Rang EH. Nasal cancer in England and Wales: an occupational survey. Br J Ind Med 1981;38:218-24. 2. Ho YM, Coman WB. Nasal septum malignancy. ANZ J Surg 2011;81:533-6. 3. Jeannon JP, Riddle PJ, Irish J, O’Sullivan B, Brown DH, Gullane P. Prognostic indicators in carcinoma of the nasal vestibule. Clin Otolaryngol 2007;32: 19-23. 4. Fradis M, Podoshin L, Gertner R, Sabo E. Squamous cell carcinoma of the nasal septum mucosa. Ear Nose Throat J 1993;72:217-21. 5. Stanley RJ, Olsen KD. Rhinectomy for malignant disease. A 20-year experience. Arch Otolaryngol Head Neck Surg 1988;114:1307-11. 6. Valentini V, Terenzi V, Bartoli D, Battisti A, Aboh IV, Egidi S, Cassoni A. Single-step nasal reconstruction with osteocutaneous forearm flap after total rhinectomy. J Craniofac Surg 2012;23:e474-6. 7. Chipp E, Prinsloo D, Rayatt S. Rhinectomy for the management of nasal malignancies. J Laryngol Otol 2011;125:1033-7. 8. Flood TR, Russell K. Reconstruction of nasal defects with implant-retained nasal prostheses. Br J Oral Maxillofac Surg 1998;36:341-5. 9. Bowden JR, Flood TR, Downie IP. Zygomaticus implants for retention of nasal prostheses after rhinectomy. Br J Oral Maxillofac Surg 2006;44:54-6. 10. Roumanas ED, Nishimura RD, Davis BK, Beumer J 3rd. Clinical evaluation of implants retaining edentulous maxillary obturator prostheses. J Prosthet Dent 1997;77:184-90. Corresponding author: Dr Elizabeth King Morriston Hospital Restorative Dentistry Department Heol Maes Eglwys Morriston, Swansea WALES Email: [email protected] Acknowledgments The authors thank Peter Llewelyn Evans for providing Figure 1. Copyright © 2016 by the Editorial Council for The Journal of Prosthetic Dentistry.
THE JOURNAL OF PROSTHETIC DENTISTRY
Orofacial rehabilitation with zygomatic implants: CAD-CAM bar and magnets for patients with nasal cancer after rhinectomy and partial maxillectomy Elizabeth King, BDS(Hons), MSc,a Carl Abbott, BSc(Hons)(Eng),b Lawrence Dovgalski, BSc(Hons),c and James Owens, BDS, MScd Malignancy of the nasal ABSTRACT septum or vestibule is rare Nasal carcinoma extending into the premaxilla requires radical surgical excision including rhineaffecting 0.3 per 100 000 of the ctomy and partial maxillectomy. Rehabilitation is complex and involves the use of removable 1 population. The risk factors prostheses. Three patients treated with zygomatic implants and custom-milled bars to retain an are poorly understood, but a obturator and nasal prosthesis are presented. (J Prosthet Dent 2016;-:---) high number of patients are smokers.2 The most common signs and symptoms after radiotherapy, and the esthetic outcome is unpreinclude nasal obstruction, epistaxis, and nasal masses.2 dictable and often poorer than a nasal prosthesis.3,6 For Squamous cell carcinoma (SCC) is the most common nasal rehabilitation, a nasal prosthesis is often better histologic type, followed by adenocarcinoma.2 Maligthan reconstruction as it allows easier postoperative nancies can invade the nasal fossa, premaxilla, upper lip, monitoring and a more predictable esthetic outcome.7 3 or nasal crest. If metastasis occurs, the lung is the most Nasal prostheses are most commonly made of silicone common site followed by the brain, bone, and skin.3 and traditionally rely on tissue undercuts and adhesive Treatment depends on the extent of disease and for retention. More recently, zygomatic implants have includes surgical excision and radiotherapy. Surgery is been shown to provide successful and predictable often the modality of choice, and if bone is involved, retention of nasal prostheses.8,9 Obturators that restore 2,4 rhinectomy is indicated. Overall 5-year survival rates the maxilla and associated dentition are frequently used are approximately 58%,3 with a high recurrence rate of for the rehabilitation of maxillary defects and also benefit 43% occurring after a mean of 9.4 months.5 from osseointegrated implants for improved retention.10 Because of the nature of surgical treatment, patients Anecdotally, patients who require restoration of orofacial with nasal malignancy can be left with substantial defects by using both obturators and nasal prostheses orofacial defects. In rare situations, nasal malignancies experience problems with loss of retention of the locally invade the maxilla, and thus treatment nasal prosthesis because of movement of the obturator involves partial maxillectomy along with rhinectomy. during function when adequate retention is not Rehabilitation includes flap reconstruction or the provided. This clinical report describes the prosthetic provision of a maxillofacial (nasal or oral) prosthesis. rehabilitation of 3 patients who underwent rhinectomy Surgical reconstruction of small defects and even comand partial maxillectomy for the treatment of nasal plete reconstruction of the nose are possibilities. malignancy, using zygomatic implant-supported nasal However, surgical morbidity is increased, particularly and oral prostheses.
a
Specialty Registrar, Restorative Dentistry, Moriston Hospital Restorative Department, Swansea, Wales. Lead Restorative Technologist, Moriston Hospital Restorative Department, Swansea, Wales. c Maxillofacial Prosthesist, Moriston Hospital Restorative Department, Swansea, Wales. d Consultant in Restorative Dentistry, Moriston Hospital Restorative Department, Swansea, Wales. b
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Her social history included smoking 10 cigarettes a day for 20 years and alcohol consumption of 7 units per week. She initially underwent partial rhinectomy, followed by radiotherapy of 60 Gy in 30 fractions. Histopathology revealed residual SCC, and more radical surgery, including rhinectomy, partial anterior maxillectomy, and selective neck dissection was undertaken. During the second surgical procedure, bilateral zygomatic implants were placed for the magnetic retention of a complete nasal prosthesis, and a surgical obturator was provided.
Figure 1. Surgical stent in situ to guide placement of zygomatic implants after rhinectomy and partial maxillectomy (blue arrows indicate approximate position of planned zygomatic implant position) (Patient 1).
CLINICAL REPORTS Patient 1 A 69-year-old man received a diagnosis of SCC of the nasal vestibule and floor of the nasal cavity in September 2013. His medical history included well-controlled hypertension. He had a smoking history of 5 cigarettes per day for 30 years and an alcohol intake of 28 to 35 units per week. He underwent rhinectomy, partial maxillectomy, and bilateral neck dissection. The upper lip skin and muscle was preserved. Bilateral zygomatic implants were placed at the time of surgery to provide magnetic retention of a complete nasal prosthesis, and a surgical obturator was provided. Histopathology revealed a completely excised, poorly differentiated SCC. Along with surgery, he received radiotherapy, 60 Gy in 30 fractions. Patient 2 In June 2013, SCC of the nasal septum was diagnosed in a 70-year-old woman. The cancer extended to the anterior maxilla. Her medical history included depression, chronic fatigue syndrome, and hyperlipidemia. Her social history included smoking 30 cigarettes per day for 30 years and an alcohol intake of 10 units per week. She underwent rhinectomy, partial maxillectomy, and bilateral neck dissection with preservation of the muscle and skin of the upper lip. Bilateral zygomatic implants were placed at the time of surgery to provide magnetic retention of a complete nasal prosthesis, and a surgical obturator was provided. Histopathology showed complete excision of poorly differentiated SCC. She received postoperative radiotherapy of 60 Gy in 30 fractions. Patient 3 Squamous cell carcinoma of the nasal septum was diagnosed in a 76-year-old woman in September 2012. THE JOURNAL OF PROSTHETIC DENTISTRY
Planning of obturator and nasal prosthesis retention For each patient, zygomatic implants were planned preoperatively to provide retention for a nasal prosthesis. Computed tomography scan data were used to plan the zygomatic implant position, and a surgical stent was made to use at the time of surgery to guide the zygomatic implant placement (Fig. 1). To simplify the orofacial rehabilitation process, it was decided that the zygomatic implants would also be used to retain the obturator prosthesis. Zygomatic implants emerging into the nasal defect were planned, as emergence into the oral cavity would limit their use for the obturator prosthesis only. Although placement of 4 zygomatic implants with both oral and nasal emergence would have been possible, this would have significantly increased surgical complexity and the risk of implant perforation. Alternative options included dental implant placement; however, placement in the anterior maxilla would require a composite free flap (bone and soft tissue), and placement in the posterior maxilla would require bilateral sinus lifts. Both of the surgical procedures would have significantly increased the surgical complexity, introduced further morbidity, and in the case of the free flap, introduced the need for a donor site. Therefore, use of the zygomatic implants for both the nasal prosthesis and obturator significantly simplified the rehabilitation process and reduced potential surgical complications. Definitive obturator construction In each situation, a definitive obturator was fabricated by a consultant in restorative dentistry and a dental laboratory technician. Maxillary and mandibular irreversible hydrocolloid impressions (Jeltrate; Dentsply Intl) were made in stock impression trays and poured with Type IV dental stone (Galaxy; Platres & Mineraux), and a maxillary custom-made impression tray was fabricated with light-polymerizing acrylic resin (Magilight; Schottlander). Maxillary impressions were then made with mediumbodied polyvinyl siloxane (Aquasil Ultra; Dentsply Intl) and poured in Type IV stone. The stone casts were duplicated with silicone (Z-Dupe; Henry Schein), and heat-polymerized acrylic resin baseplates covering the edentulous areas and obturating the maxillary defect were fabricated along with wax occlusion rims to record King et al
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2016
3
Figure 2. Magnet polymerized into position in obturator (Patient 1).
centric relation. The definitive tooth arrangement was developed on the baseplates and evaluated chairside, and the obturator was processed with acrylic resin (PalaXpress Ultra; Heraeus Kulzer Inc). After the computeraided design and computer-aided manufacturing (CAD-CAM) bar was evaluated for fit, an impression of the magnet in situ on the bar was made in the definitive obturator with medium-bodied polyvinyl siloxane (Occlufast Rock; Zhermack SpA). The magnet was then secured with autopolymerizing acrylic resin (Meadway Rapid Repair; MR. Dental) (Fig. 2). CAD-CAM bar construction After the definitive obturator was fitted, computed tomography data were evaluated to establish the osseointegrated hard tissue support provided by the zygomatic implants, and it was determined that the implants could be used to retain a CAD-CAM bar which would simultaneously retain both maxillofacial prostheses. For Patient 1, a polyvinyl siloxane impression (Aquasil Ultra; Dentsply Intl, Occlufast; Zhermack) of the implants and nasal defect was made with the definitive obturator in situ (Fig. 3). Type IV dental stone with 2 fixture replicas (Multi-unit Abutment Plus Replica; Nobel Biocare) was used to produce a definitive cast. Two nonengaging interim abutments (Abutment Replica Multi-Unit Brånemark System; Nobel Biocare) splinted with acrylic resin (GC Pattern Resin LS, GC America) were used to verify the accuracy of the impression and to ensure that the bar could be removed passively, considering the divergence of the implants (Fig. 4). The working cast was scanned (D800 Desktop Scanner; 3Shape), and data were imported into CAD software King et al
Figure 3. Silicone impression of zygomatic implants and nasal defect with obturator in situ (Patient 1).
Figure 4. Resin bar verification of zygomatic implants (Patient 1).
(3D Shape). The anatomy was assessed, and a crucifixshaped bar was designed to allow the horizontal splinting of the implants, incorporation of 2 magnets (Brånemark Mini Magnabutment; Technovent Ltd) for nasal prosthesis retention and incorporation of an attachment on the inferior aspect to retain a magnet (Brånemark Maxi Magnabutment; Technovent Ltd) for obturator retention (Fig. 5). An acrylic resin prototype of THE JOURNAL OF PROSTHETIC DENTISTRY
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Figure 5. CAD design of crucifix-shaped bar (Patient 1).
Figure 6. Crucifix-shaped bar in situ (Patient 1).
Figure 7. Example of T-shaped bar and obturator in situ (Patient 2).
the bar was fabricated. The bar was scanned and imported into the CAD software and sent to a milling company (Core 3D). The original design could not be fabricated as the milling unit would not accommodate the bar shape. This was overcome by redesigning the bar as 2 separate components, the crucifix-shaped bar and the magnet attachment. At the time, only cobaltchromium (Co-Cr) ingots were available; therefore, components were milled in Co-Cr and laser welded together. Two magnets were screwed into the bar, and 1 magnet was bonded into the cup-shaped attachment with dual-polymerizing composite resin (GC Gradia Composite; Terec Ltd). Figure 6 shows the crucifixshaped bar and obturator in situ. Patients 2 and 3 were treated in the same way patient 1 was; however, because of differences in anatomy, a THE JOURNAL OF PROSTHETIC DENTISTRY
Figure 8. Clinical outcome of obturator and nasal prosthesis retained by crucifix-shaped bar (Patient 1).
T-shaped bar (Fig. 7) was used instead of the crucifixshaped bar. Second, the milling company (Core 3D) had meanwhile obtained titanium milling ingots, and the bar components were milled in titanium. Nasal prosthesis fabrication Immediately after surgery, each patient was fitted with a nasal prosthesis attached to glasses. After soft tissue healing, a maxillofacial prosthetist fabricated a King et al
-
2016
magnetically retained nasal prosthesis. In addition, a polymerized silicone impression with the bar and magnets in situ was made. Magnet analog fixtures were located on top of the impression magnets, and the impression was poured in gypsum (Crystacal R Plaster; SWIP Dental). A baseplate was fabricated with magnets and lightpolymerized resin (Triad Gel; Dentsply Intl) and evaluated to verify the accuracy of the cast. A wax prototype was fabricated from a preoperative computed tomography scan in CAD software (Freeform; Geomagics) to define the shape. A postoperative 3D surface scan (5-pod; 3DMD) was made, and the preoperative nose was adjusted to form a virtual nasal prosthesis. This was fabricated in stereolithography resin (PDR) and duplicated in wax (Anutex; Kemdent). Finally, the wax prototype was incorporated into the baseplate, and definitive carving was conducted at the clinical evaluation appointment. A gypsum cast of the wax prototype was produced and the wax was eliminated. The plaster cast was filled with silicone elastomer (Cosmesil HC2; Cosmesil), color matched, and polymerized. Figure 8 shows the definitive nasal prosthesis and obturator in situ.
5
However, maxillofacial prostheses are not without caveats, and the potential complications of the prostheses described in this article include risk of zygomatic implant infection, irritation of supporting tissues, lifelong prosthesis maintenance, and significant patient cooperation for successful acclimatization. Specific difficulties described by the patients include degradation of nasal prosthesis, food leakage, dropping of posterior borders of the obturator, and generalized discomfort. A specific problem occurred for Patient 2; the titanium bar fractured at the welding spot soon after placement. Titanium is more difficult to weld than Co-Cr because of the need for a pure argon environment. The weld was repeated with no further problems. All 3 bars, obturators, and nasal prostheses fit well and were clinically stable and retentive. As of the present writing, 2 patients are functioning well with their prostheses, but 1 patient struggled psychologically with the appearance of the bar, so it was not fitted. Instead she has a magnetically retained nasal prosthesis with an obturator retained with soft tissue undercuts. REFERENCES
DISCUSSION Rehabilitation of patients after rhinectomy and partial maxillectomy requires a multidisciplinary team which includes maxillofacial surgeons, consultants in restorative dentistry, maxillofacial prosthetists, and appropriately trained dental laboratory technicians. Reconstructions should aim to improve esthetics and function in the immediate and long term, as well as allow examination of the tissues to monitor recurrence. The benefits of the maxillofacial prostheses described in this article include active retention of the obturator and nasal prosthesis with magnetic retention; improved ability to re-establish functions such as speech, mastication, and swallowing; improved ability to recover social life as soon as possible after surgery; ability to remove both prostheses to allow examination of tissues; ease of insertion and removal of prostheses by the patient; provision of upper lip support from the obturator, and avoidance of further invasive surgical procedures (such as dental implant placement, bone grafting) for obturator retention. Use of zygomatic implants for the concurrent retention of obturator and nasal prostheses significantly simplifies orofacial rehabilitation and removes the need of further invasive surgical procedures.
King et al
1. Acheson ED, Cowdell RH, Rang EH. Nasal cancer in England and Wales: an occupational survey. Br J Ind Med 1981;38:218-24. 2. Ho YM, Coman WB. Nasal septum malignancy. ANZ J Surg 2011;81:533-6. 3. Jeannon JP, Riddle PJ, Irish J, O’Sullivan B, Brown DH, Gullane P. Prognostic indicators in carcinoma of the nasal vestibule. Clin Otolaryngol 2007;32: 19-23. 4. Fradis M, Podoshin L, Gertner R, Sabo E. Squamous cell carcinoma of the nasal septum mucosa. Ear Nose Throat J 1993;72:217-21. 5. Stanley RJ, Olsen KD. Rhinectomy for malignant disease. A 20-year experience. Arch Otolaryngol Head Neck Surg 1988;114:1307-11. 6. Valentini V, Terenzi V, Bartoli D, Battisti A, Aboh IV, Egidi S, Cassoni A. Single-step nasal reconstruction with osteocutaneous forearm flap after total rhinectomy. J Craniofac Surg 2012;23:e474-6. 7. Chipp E, Prinsloo D, Rayatt S. Rhinectomy for the management of nasal malignancies. J Laryngol Otol 2011;125:1033-7. 8. Flood TR, Russell K. Reconstruction of nasal defects with implant-retained nasal prostheses. Br J Oral Maxillofac Surg 1998;36:341-5. 9. Bowden JR, Flood TR, Downie IP. Zygomaticus implants for retention of nasal prostheses after rhinectomy. Br J Oral Maxillofac Surg 2006;44:54-6. 10. Roumanas ED, Nishimura RD, Davis BK, Beumer J 3rd. Clinical evaluation of implants retaining edentulous maxillary obturator prostheses. J Prosthet Dent 1997;77:184-90. Corresponding author: Dr Elizabeth King Morriston Hospital Restorative Dentistry Department Heol Maes Eglwys Morriston, Swansea WALES Email: [email protected] Acknowledgments The authors thank Peter Llewelyn Evans for providing Figure 1. Copyright © 2016 by the Editorial Council for The Journal of Prosthetic Dentistry.
THE JOURNAL OF PROSTHETIC DENTISTRY