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Orofacial rehabilitation with zygomatic implants, CAD-CAM bar and magnets for patients with nasal cancer after rhinectomy and partial maxillectomy

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INTRODUCTION

Malignancy of the nasal septum or vestibule is rare affecting 0.3 per 100,000 of the population.1 The risk factors are poorly understood, but a high number of patients are smokers.2 Malignancies can invade the nasal fossa, premaxilla, upper lip, or nasal crest.3 Surgery is often the treatment of choice, and, if bone is involved, rhinectomy is indicated.2,When lesions invade the maxilla, treatment also involves partial maxillectomy.

Patients with nasal malignancy can be left with substantial defects. Although surgical rehabilitation it possible, a nasal prosthesis is often preferred as it reduces surgical morbidity, simplifies postoperative monitoring and provides a more predictable aesthetic outcome. Nasal prostheses traditionally rely on tissue undercuts and adhesive for retention. More recently zygomatic implants have been shown to provide successful and predictable retention of nasal prostheses.4,5 Obturator prostheses also benefit from osseointegrated implants for retention.6This clinical report describes the prosthetic rehabilitation of 3 patients who underwent rhinectomy and partial maxillectomy for the treatment of nasal SCC using zygomatic implant-supported nasal and oral prostheses.

ONCOLOGICAL TREATMENT

Patient 1

•69-year-old male diagnosed with nasal SCC September 2013 – maxillary infiltration present.
•Social history – 5 cigarettes per day for 30 years; 28 to 35 units of alcohol per week.

Oncological treatment

•Rhinectomy, partial maxillectomy, and bilateral neck dissection – skin and muscle of the upper lip preserved.
•Bilateral zygomatic implants, nasal prosthesis and surgical obturator placed at the time of surgery.
•Radiotherapy – 60 Gy in 30 fractions.

Patient 2

•70-year-old female diagnosed with nasal SCC June 2013 – maxillary infiltration present.
•Social history – 30 cigarettes per day for 30 years; 10 units of alcohol per week.

Oncological treatment

•Rhinectomy, partial maxillectomy, and bilateral neck dissection – skin and muscle of the upper lip preserved.
•Bilateral zygomatic implants, nasal prosthesis and surgical obturator placed at the time of surgery.
•Radiotherapy – 60 Gy in 30 fractions. 

Patient 3

•76-year-old female diagnosed with nasal SCC September 2013 – maxillary infiltration present
•Social history – 10 cigarettes a day for 20 years; 7 units of alcohol per week

Oncological treatment

•Initial partial rhinectomy plus radiotherapy (60 Gy in 30 fractions) – histopathology revealed residual SCC.
•More radical surgery, including rhinectomy, partial anterior maxillectomy, and selective neck dissection was undertaken.
•Bilateral zygomatic implants, nasal prosthesis and surgical obturator placed.
 

PLANNING THE REHABILITATION

The CT scan was to plan implant position and a stereolithographic stent was used at the time of surgery (Fig. 1). 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 4 zygomatic implants with both oral and nasal emergences would have been possible, this was decided against due to increased surgical complexity and risk of implant perforation. An alternative option included dental implant placement; however placement in the anterior maxilla would require a composite free flap and placement in the posterior maxilla would require bilateral sinus lifts. Both 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.

TREATMENT BENEFITS

•Active retention of the obturator and nasal prosthesis using magnetic retention.
•Improved ability to re-establish functions such as speech, mastication, and swallowing as soon as possible.
•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.
•Avoidance of further invasive surgical procedures (e.g. dental implant placement, bone grafting) for obturator retention.

TREATMENT CAVEATS

•Risk of zygomatic implant infection.
•Irritation of supporting tissues.
•Lifelong prosthesis maintenance.
•Significant patient cooperation for successful acclimatization. 

DEFINITIVE OBTURATOR FABRICATION

A definitive obturator was fabricated by a consultant in restorative dentistry and a dental laboratory technician.

1.Maxillary and mandibular alginate impressions were made in stock trays.
2.A custom impression tray was fabricated and maxillary secondary impressions were made in silicone.
3.Acrylic baseplates (plus bung) were fabricated with wax occlusion rims to record centric relation.
4.The definitive tooth arrangement was recorded chairside.
5.The obturator was processed with acrylic resin.

CAD-CAM BAR FABRICATION

The following describes the treatment for Patient 1:

1.A silicone impression of the implants and nasal defect was made with the obturator in situ (Fig. 2).
2.Type IV dental stone with 2 fixture replicas was used to produce a definitive cast.
3.2 interim abutments splinted with acrylic resin were used to verify the accuracy of the impression and ensure passive insertion (Fig. 3).
4.The working cast was scanned and the data imported into CAD software (3D Shape).
5.A crucifix-shaped bar was designed to allow:
•Horizontal splinting of the implants.
•Incorporation of 2 screw retained anterior magnets for nasal prosthesis retention.
•Incorporation a magnet on the inferior surface for obturator retention (Fig. 4).
6.An acrylic resin prototype of the bar was fabricated.
7.The prototype bar was scanned, and sent to a milling company (Core 3D) to be milled in Co-Cr.
8.The crucifix bar and obturator were fitted (Fig. 5).
9.The large magnet was placed in situ on the bar and a pick-up impression was made in the definitive obturator.
10.The magnet was secured with auto-polymerising acrylic resin (Fig. 6).

Patients 2 and 3 were treated following a similar sequence; however, because of differences in anatomy, a T-shaped bar (Fig. 7) was used instead of the crucifix shape. Secondly, the milling company (Core 3D) had sourced 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 magnetically retained nasal prosthesis.

1.A silicone impression with the bar and magnets in situ was made.
2.Magnet analogs were located on top of the impression magnets and the impression was poured in gypsum.
3.A baseplate was fabricated with magnets and light-polymerised resin to verify the accuracy of the cast.
4.A postoperative 3D surface scan (5-pod; 3DMD) was made and the preoperative nose adjusted to form a virtual nasal prosthesis.
5.The virtual prosthesis was fabricated in stereolithographic resin and duplicated to make a wax prototype.
6.The wax prototype was incorporated into the baseplate and tried in.
7.A cast of the wax prototype was produced to process the silicone definitive nasal prosthesis.
8.The definitive nasal prosthesis was fitted alongside the obturator (Fig. 8).
 

REFERENCES

1. Acheson ED, Cowdell RH, Rang EH. Nasal cancer in England and Wales: an occupational survey. Br J Ind Med 198;38:218-24.

2. Ho YM, Coman WB. Nasal septum malignancy. ANZ J Surg 2011;81:533-6.

3. Jeannon JP, Riddle PJ, Irish Jet al. Prognostic indicators in carcinoma of the nasal vestibule. Clin Otolaryngol 2007;32:19-23.

4. Flood TR, Russell K. Reconstruction of nasal defects with implant-retained nasal prostheses. Br J Oral Maxillofac Surg 1998;36:341-5.

5. Bowden JR, Flood TR, Downie IP. Zygomaticus implants for retention of nasal prostheses after rhinectomy. Br J Oral Maxillofac Surg 2006;44:54-6.

6. 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.

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