Reconstruction of the Nose and the Maxillary Arch: The Gift of a Challenge

INTRODUCTION
Squamous cell carcinoma (SCC) is the most common type of head and neck malignancy.^1,2 This type of carcinoma accounts for greater than 50% of the malignancies of the paranasal sinuses and the nasal cavity.^3,4 SCCs may be treated by surgical excision, cryotherapy, and/or radiation.⁵ Depending on the lesion size and location, surgical removal may result in a defect requiring reconstruction. Large defects may affect phonetics, mastication, swallowing, airflow, aesthetics, and social relationships.^6-8 Excisional surgery and consequent outcomes can negatively impact the patient’s psychology.⁶ It is critical to reconstruct surgical defects in a timely manner in order to restore optimal form and function to the extent possible.

Large mid-facial defects can be challenging to rehabilitate due to multiple factors, such as retention problems, soft-tissue mobility, and the weight of the prosthesis.⁸ The mode of retention for prostheses should be addressed during the treatment planning stage. Patients may present with insufficient residual alveolar ridge anatomy or poor tissue quality following surgical intervention to support and retain a prosthesis. Anatomic undercuts, dental adhesives, implants, and attachments can be utilized to support and retain the prosthesis.^8,9 Use of a dental adhesive for retention of an extraoral prosthesis creates unique problems, including poor long-term bond strength; unpredictable periods of retention; degradation of the prosthetic material, especially at the borders of a prosthesis; and failure of retention when the patient performs functional movements.¹⁰ The utilization of implants as a means to retain a prosthesis not only improves retention but also improves stress distribution, masticatory function, and quality of life.^11,12 Osseointegrated implants may provide the most reliable form for prosthesis retention; however, an extensive size of the defect, poor mucosal quality, and minimal bony supporting structures may preclude the use of implants.⁸

Computer-aided design/computer-aided machining (CAD/CAM) technologies related to imaging and manufacturing provide a simple, accurate, and predictable solution for the optimal reconstruction of maxillofacial defects.^13-16 Advanced technologies can be combined with conventional procedures for the reconstruction of complex anatomical structures. CAD/CAM technologies aid in reducing the number of procedural steps and eliminating the need for multiple impressions and records.¹³ However, clinicians should consider the cost implications, the accuracy of the CAD/CAM manufacturing system, and the biomaterials used prior to implementing a system.¹³

The patient in this article was left with a nasomaxillary facial defect due to the prescribed surgical intervention and excision of the SCC and subsequent radiation therapy. This clinical case report describes the prosthodontic rehabilitation of the patient with a CAD/CAM-manufactured nasal prosthesis attached to an implant-retained intraoral prosthesis using a magnet and a LOCATOR attachment system (Zest Dental Solutions). At the 2-year follow-up appointment, the patient reported that he was very satisfied with his prostheses.

CASE REPORT
A 67-year-old white male patient (a retired army veteran) was referred to the Oral and Maxillofacial Surgery Department at the Overton Brooks VAMC in Shreveport, La, for loose front teeth, exposed bone, and nasal reconstruction. The patient presented several years after undergoing a total rhinectomy and 7,000 centigray (cGy) of radiation for intranasal SCC (Figure 1). The patient functioned without a prosthesis since completion of the rhinectomy and subsequent radiation therapy and used a surgical mask whenever he stepped out of the house to avoid social embarrassment.

A comprehensive oral examination and diagnosis revealed that the patient had developed stage III osteoradionecrosis of the premaxilla. Osteonecrosis is commonly seen in the posterior mandible and is usually treated by the use of microvascular surgery.^17,18 Additional comorbid considerations in the patient’s medical history included severe peripheral vascular disease, coronary bypass surgeries (including the placement of several cardiac stents), and lung cancer. The patient was considered “high-risk” by the anesthesiologist for extended surgical procedures. The initial treatment included removal of the premaxilla and extraction of the maxillary anterior teeth (Figure 2). This surgery resulted in a defect that created an oronasal fistula (Figure 3). The nasal prosthesis fabrication, combined with dental prosthetic rehabilitation, was complicated by the loss of the premaxilla/nasal floor. An interim partial obturator prosthesis and a nasal prosthesis were fabricated for the patient. The design of the partial obturator prosthesis included an extension into the nasal cavity (Figures 4 and 5). A magnet was incorporated in the nasal portion of the prosthetic extension to provide retention to the silicone nasal prosthesis. The interim nasal prosthesis had poor retention, so the patient was instructed to use an adhesive to improve retention. The prosthesis frequently dislodged during function, and the patient expressed discomfort.

It was determined through his postoperative period that the remaining maxillary teeth would be lost due to periodontal disease and chronic xerostomia. Since the field of radiation was restricted to the premaxilla, dental implants were planned in the posterior maxilla to improve the obturator retention. Due to the complexity of the case, the restorative dentist, oncologist, and oral and maxillofacial surgeon worked as a team in patient management. The treatment plan included the removal of any further necrotic osseous structures and remaining dentition encased in the necrotic bone and prescribed implant placement to aid in retention of the oral prosthesis. Pre-existing systemic diseases precluded the use of microvascular tissue grafts for managing the oronasal defect.

A new interim partial obturator prosthesis was fabricated for the patient (Figure 6a). Maxillary teeth were extracted because of periodontal disease and decay from xerostomia; prosthetic teeth were added to the partial obturator prosthesis as necessary (Figure 6b). Following each extraction, the site was evaluated carefully to determine if implant placement was possible (Figure 7).

Fabrication of the Interim Complete Obturator
Final impressions were made and maxillo-mandibular jaw relation records were registered to fabricate an immediate overdenture for the patient. The necrotic bone and all the remaining maxillary teeth were extracted; implants were placed; and the transitional overdenture prosthesis was adjusted, finished, polished, and lined with a soft lining material (Figure 8). Although several implants were placed initially, only 6 (Replace Select Tapered [Nobel Biocare]) implants integrated successfully. LOCATOR attachments were connected to the implants for maxillary overdenture retention and support, and the attachment housings were picked up chairside as per the manufacturer’s recommendations. The patient was instructed and he acknowledged that the definitive prostheses would be fabricated once the interim prostheses were determined to have optimum retention and stability and the patient confirmed satisfaction with the comfort and fit of the prostheses. Several interim intraoral prostheses were fabricated for the patient. It was determined that the prosthesis extension into the nasal cavity would be required to help retain the nasal prosthesis; however, it would be designed to meet patient comfort. Measurements were made to gauge the size of the prosthesis extension (Figure 9), and then several design renditions were fabricated to assess patient comfort. Nasal prosthesis retention using a magnetic attachment (Technovent Ltd) alone resulted in the loss of retention during function as well as following attempts using additional magnets. The decision was made to use both a magnetic attachment and a LOCATOR attachment incorporated into the prosthetic extension to provide optimal retention of the nasal prosthesis. The magnet would aid in providing the correct path of insertion to the nasal prosthesis, and the LOCATOR attachment would help secure it in position.

Fabrication of the Definitive Obturator
After a healing period, procedures for fabricating a maxillary implant-supported obturator prosthesis were initiated. LOCATOR R-Tx attachments (Zest Dental Solutions) were used to retain the intraoral obturator prosthesis (Figure 10). A heavy-viscosity impression material (Honigum Rigid (X-tra Fast [DMG America]) was used to record borders including the defect, followed by a wash impression using thermoplastic impression trays (Strong-Massad Denplant LOW TEMP Tray [Nobilium]) (Figure 11). After interocclusal records were registered, the metal framework design and other materials were sent to the laboratory for the fabrication of the obturator prosthesis. The metal framework was planned for the definitive prosthesis to include an extension intended to support the material into the nasal cavity to improve strength and fracture resistance (Figures 12a to 12d). Beads, a magnet, and a LOCATOR attachment (Figures 12e to 12g) were incorporated in the prosthesis extension to aid in retention of the nasal prosthesis. The prosthesis was adjusted, finished, polished, and delivered for intraoral placement.

Fabrication of the Nasal Prosthesis
Fabrication of the nasal prosthesis was initiated after ensuring that the maxillary obturator prosthesis was retentive and comfortable to the patient. An evaluation of the patient’s presurgical images revealed that his nose appeared small relative to other facial features (Figure 13). It was challenging to create a smaller-sized nose while attempting to use the prosthesis to mask the scar line.

Rigid impression material (Honigum Rigid regular set [DMG America]) with an extended setting time was placed over the facial void and shaped to resemble the patient’s nose (Figure 14a). Reference lines were drawn from peripheral borders to the surrounding tissues (Figure 14b) to help align it in an optimal position while recording the borders and the intaglio surface with a lighter-viscosity impression material (Aqualsil Ultra [Dentsply Sirona]) (Figures 14c and 14d). The nasal impression was indexed, and a mold was created using laboratory putty material (Nobilium Putty Base and catalyst [Nobilium]). The impression was removed from the mold, and melted dental wax was poured into the void to develop a wax pattern of the nose (Figure 15). The wax pattern was placed on the patient’s face for a try-in procedure to verify the contour, surface texture, and position of the wax pattern. The marginal adaptation of the wax pattern was refined by relining it with an elastomeric impression material (Honigum Mono Phase regular set [DMG America]). After verification of the fit and aesthetics, patient approval was obtained, and the wax pattern was used to fabricate the silicone nasal prosthesis (Figure 16) using the compression molding procedure. In order to incorporate retentive elements of the attachments in the silicone material for the nasal prosthesis, a metal framework was incorporated in the design of the nasal prosthesis to house the retention magnet and LOCATOR attachment. At the recall appointments, it was observed that the patient was unable to properly clean the nasal prosthesis. The problems with silicone material included its high porosity, odor and staining after use, and deterioration of the thin border materials. Hence, it was prudent to select another material. A CAD/CAM-printed resin nasal prosthesis (Dentca Denture Resin [Whip Mix]) was planned for the patient; it could be digitally altered and then printed. The silicone prosthesis was scanned, design alterations were made in the software (exocadad software [exocad America]), and a printed prosthesis was generated for the patient (Asiga 3D Printer [Whip Mix]).

Various trial nasal prostheses were made for the patient (Figure 17). The patient indicated that when he didn’t have enough air velocity, he would get dizzy. It was important to fabricate a nasal prosthesis that was hollow to permit optimal air velocity and respiratory function (Figure 18). A CBCT scan (HDX WILL) (Figure 19) was taken with the trial prosthesis to ensure optimal patient function. The accepted trial nasal prosthesis was printed (Figure 20), tried, adjusted, and finished. It was placed in position, and reference lines were drawn from peripheral borders to the surrounding tissues to help align it in optimal position during the direct attachment housing pickup procedure. The intaglio surface of the nasal prosthesis was relieved to facilitate pickup of the magnet and the attachment housing. The magnet and the retentive housing of the LOCATOR attachment were picked up chairside as per the manufacturer’s recommendation (Figure 21).

The hard borders of the nasal prosthesis impinged on the scar tissues, causing the patient pain and discomfort. Hence, diatorics were created on the intaglio surface (to provide retention to the liner), and the printed nasal prosthesis was lined with a long-term, polyphosphazene-based, resilient lining material (Novus [White Square Chemical]) using a laboratory reline technique (Figure 22). The procedure included investing the nasal prosthesis in a traditional compression molding flask, appropriately relieving the borders and intaglio surface of the prosthesis, placing the resilient liner, and polymerizing it with a long or short curing cycle, followed by the finishing and polishing protocol.

Two sets of the nasal prostheses were made: The first nasal prosthesis was designed and tinted to be worn during daytime (tinted to match the patient’s skin color in daylight) and the other to be worn at night (tinted to match his skin color in nighttime light or low illumination). Divots were created on the nasal prostheses to give them a natural appearance (Figure 23a). The nasal prostheses were tinted (Optiglaze [GC America]) and stained (Minute Stains [TAUB Products]) to achieve a more lifelike appearance and to match different shades of the patient’s natural skin tones (Figures 23b and 23c). It was easy not only to tint them but also to eliminate the tinting with a slow-speed rotary instrument.

The printed prostheses were easy to clean and maintain. The patient was very comfortable with both the intraoral and nasal prostheses (Figure 24). Patient instructions were reviewed and rehearsed for insertion and removal of the prostheses. The patient was educated and taught to use an electric toothbrush (Oral B iO series 9 electric toothbrush [Procter & Gamble]) to massage his tissues and optimally clean his oral cavity and prostheses (Figures 25 and 26). The patient was placed on a regular maintenance regimen.

CONCLUSION
In this clinical report, the nasal prostheses were fabricated using printed resin lined with a resilient material. The printed resin nasal prostheses were fabricated using CAD/CAM technology, which simplified the fabrication procedures. The technology permitted the fabrication of several prostheses, eliminating the need for the repeated impressioning and records appointments that would typically occur following conventional laboratory fabrication procedures when a patient needs a new prosthesis. In addition, utilization of a LOCATOR attachment and a magnet for retaining the extraoral prostheses precluded the need for the use of an adhesive and helped achieve a successful result.

Acknowledgments:
The authors would like to acknowledge CAD/CAM technicians Mr. Johnny Orfanidis, Mr. Craig Nelson, and Mr. Al Ranger for their support. Dr. Massad would also like to acknowledge Mr. Kenneth Wado at Lords Dental Lab (National Dentex Corporation).

References

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Dr. Massad is an associate professor in the department of graduate prosthodontics at the University of Tennessee Health Science Center College of Dentistry in Memphis; clinical professor at the University of Oklahoma College of Dentistry in Oklahoma City; and an associate faculty at the Tufts University School of Dental Medicine in Boston; an adjunct associate faculty of the department of comprehensive dentistry at the University of Texas Health Science Center at San Antonio (UT Health San Antonio) School of Dentistry; and an adjunct professor in the department of restorative dentistry at Loma Linda University in Loma Linda, Calif. He has a private practice in Tulsa, Okla. He can be reached at joe@joemassad.com.

Dr. Garcia is dean and a professor at the University of Nevada, Las Vegas School of Dental Medicine. She was in private practice in Denver early in her career, then served as faculty at the University of Colorado Health Sciences Center School of Dentistry, as department chair of prosthodontics at UT Health San Antonio, and as professor and associate dean for education at the University of Iowa College of Dentistry. She can be reached at lily.t.garcia@univ.edu.

Dr. Goodacre holds the title of distinguished professor and teaches in the Advanced Education Program in Implant Dentistry at Loma Linda University. He is a Diplomate and past president of the American Board of Prosthodontics, past president of the American College of Prosthodontists, and past president of the Academy of Prosthodontics. He can be reached at cgoodacre@llu.edu.

Dr. Ahuja worked at the University of Tennessee Health Science Center in Memphis as an assistant professor in department of prosthodontics for 3 and a half years. She has lectured nationally and internationally on various prosthodontic topics at various dental conferences. She has more than 50 publications in peer-reviewed national and international journals and is also the co-author of the textbook Applications of the Neutral Zone in Prosthodontics. She is a consultant scientific writer and a consulting prosthodontist for several private dental clinics in Mumbai, India, and also for NYU Langone Medical Center in New York. She can be reached at swatiahuja@gmail.com.

Dr. Shirley is an assistant professor of oral and maxillofacial surgery at Oschner-Louisiana State University Health Sciences Center Shreveport. He is a Diplomate of the American Board of Oral and Maxillofacial Surgery and a Fellow of the American College of Surgeons and holds a certificate of added qualifications in Head and Neck Oncologic and Reconstructive Surgery. He can be reached at brettshirleyddsmd@gmail.com.

Disclosure: The authors report no disclosures.

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