CLINICAL REPORT

Fabricating a partial nasal prosthesis with a custom nasal

dilator design
Po-Hsu Chen, DDS, MS,a Julius C. Seidenfaden, CDT,b Michael T. Kase, DMD,c and Iradj Sooudi, DDS, DMDd

A rhinectomy is indicated ABSTRACT

either as a part of cancer
Patients undergoing partial rhinectomy with limited size may have the major portion of the nasal
treatment or after nasal structure preserved. However, the fibrosis or scar formation after the surgery may cause distortion
1
trauma. Although the proper of remaining tissues, followed by nasal airway obstruction. By physically expanding an affected
healing of the resection site is nostril during the impression and using digital technology to design a custom flexible internal
necessary before making the nasal dilator, embedded in the medical grade silicone during processing, a partial nasal
impression for the definitive prosthesis with airway-maintaining purpose can be fabricated to improve quality of life both
prosthesis, the continuous esthetically and functionally. (J Prosthet Dent 2020;-:---)
contraction and remodeling of
the surrounding tissue during the healing period could outcome than an external one in improving sleep quality
delay the impression for at least 3 months after the or the apnea index for snorers.7,9
2 ,3 Because of the limited airway patency of patients that
surgery. Furthermore, when a nose is supported by the
nasal bone and cartilage, resecting a part of the sup- require the restoration of both an esthetic and functional
porting structure, a partial rhinectomy, may lead to loss airway after a partial rhinectomy, the digital workflow of
of patency of the airway by displacing residual nasal fabricating a silicone nasal prosthesis incorporated with
structures, constriction, contraction, and collapse of the the internal nasal dilator design is described.
tissue during the healing process.4,5 Adjuvant radio-
therapy is sometimes necessary for further managing the CLINICAL REPORT
cancer,1 but it also leads to radiation-induced fibrosis
A 66-year-old white woman presented with a history of
(RIF). Radiation-induced fibrosis can cause skin indura-
squamous cell carcinoma over the right side of the nasal
tion, thickening, muscle shortening, atrophy, and is
septum, which had been excised and grafted with a split-
related to the extended disfigurement of the affected
thickness skin graft in 2013. Then, in 2016, a papillo-
tissue6; thus, more constriction of the nasal airway may
matous lesion along the side wall of the right nasal
be expected after the rhinectomy.
vestibule was noticed and diagnosed as squamous cell
Different designs of nasal dilators have been pro- carcinoma. She then underwent the partial intranasal
posed and used for airway maintenance in patients with rhinectomy with 62 Gy of adjuvant radiotherapy. In 2019,
deformities of the nose, obstructive sleep apnea,7 or a new exophytic lesion was discovered at the side wall of
athletes during heavy exercise and recovery.8 An external the right nasal vestibule and was diagnosed as recurrent
(nasal strip) or internal nasal dilator can be used for keratinizing squamous cell carcinoma. Because of the
expanding the nasal passage based on different ap- previous history of radiotherapy, additional radiation
proaches. An internal nasal dilator generally has a better exposure was not indicated. Thus, another wide local

a
Fellow, Advanced Education in Maxillofacial Prosthetics, Department of Restorative Sciences, University of Alabama at Birmingham School of Dentistry, Birmingham, Ala.
b
Dental Prosthetist, Department of Restorative Sciences, University of Alabama at Birmingham School of Dentistry, Birmingham, Ala.
c
Assistant Professor, Department of Oral and Maxillofacial Surgery, University of Alabama at Birmingham School of Dentistry, Birmingham, Ala.
d
Adjunct Associate Professor, Department of Restorative Sciences, University of Alabama at Birmingham School of Dentistry, Birmingham, Ala.

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Figure 2. Three months after surgery. Swirling of remaining tissue at

right nares caused obstruction of airway.

nasal contour and expand the airway, a nasal prosthesis

incorporated with the internal nasal dilator was planned.
A mixing tip for an impression material (Aquasil Mixing
Tips Green; Dentsply Sirona) was cut and inserted into
the right nostril to expand it intentionally to a level that
was tolerable for her. Light-body, heavy-body (Aquasil
Ultra; Dentsply Sirona), and putty-type (Splash Half-
Time Set Putty; DenMat) polyvinyl siloxane impression
material was applied around the inserted mixing tip. The
complete impression was removed along with the mixing
tip (Fig. 3).
The impression was scanned with a desktop scanner
(D900-L Scanner; 3Shape A/S), and a digital cast was
Figure 1. Patient with malignancy at intranasal region. Partial
created with a computer-aided design (CAD) software
rhinectomy planned. program (Model Builder; 3Shape A/S) and then exported
in standard tessellation language (STL) format. The file
was transferred to a 3D printing machine (MAX; Asiga)
excision was planned, which would lead to a noticeable to create a printed cast with light-polymerized resin
external nasal defect. She was referred to the maxillofa- (VeriModel OS Ivory Resin; Whip Mix Corp). In addition,
cial prosthetics clinic for a consultation on the prosthetic a frame of the internal nasal dilator was designed by the
reconstruction of the right nasal alar region before the CAD software with a removable partial denture
surgery. The unsymmetrical alar contour between left designing module (Dental System; 3Shape A/S) and was
and right sides was noticed, likely caused by the made slightly larger than an appropriate right nostril size.
contraction from previous intranasal resection and The frame was composed by the 3 quarters round part as
radiotherapy (Fig. 1). the actual dilator portion, which was facing inward, and
The recent surgical interventions did not allow for the handle portion that was facing outward to be sub-
immediate commencement of the definitive prosthetic sequently connected to the nasal prosthesis (Fig. 4). The
phase. Because of the limited size of the defect, an frame was fabricated by a milling machine (DWX-51D;
interim nasal prosthesis was determined to be unnec- Roland DGA) with flexible removable partial denture
essary. After 3 months of healing, the defect had healed framework material (VisiClear CAD; Myerson); slight
well and was completely epithelialized, with no early adjustment of the walls around the nostril on the cast
evidence of intranasal recurrence. She was referred to the was made to allow the frame to be inserted (Fig. 5).
maxillofacial prosthetic clinic by the otolaryngologist for Multiple holes were drilled on the handle portion of the
the definitive nasal prosthesis. frame to increase the mechanical retention for attached
She presented with the contracted right nasal contour materials. Hard pink wax (TruWax Baseplate Wax Extra
with a centimeter notch in the free edge of the ala Hard; Dentsply Sirona) was used for waxing the nasal
(Fig. 2). She reported difficulty in breathing from the right prosthesis contour directly on the printed cast, which was
nostril, becoming more severe over time. To restore the connected to the nasal dilator frame. During the wax

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Figure 4. Designing internal nasal dilator frame in Dental System

software.

Figure 3. A, Impression made with right nostril expanded. B, Completed

impression.

evaluation appointment, the general contour of the nasal Figure 5. Inserting dilator frame into printed cast.
prosthesis was verified with her. In addition, the airway
was improved significantly without causing intolerable minutes. The frame was then covered by the silicone
tissue pressure around the right nostril (Fig. 6). She adhesive (A-100; Factor II) and inserted into the cast
verified and approved the intended outcome and agreed properly. The stained unpolymerized silicone (VST-50;
to have the definitive prosthesis processed. The skin color Factor II) was packed into and around the right nostril
and tone were recorded as the intrinsic staining reference followed by closing the lid completely, and a rubber band
for subsequent silicone processing. was wrapped around the mold assemble after the excess
The wax pattern was repositioned on the cast, fol- material had been removed. It was left to polymerize
lowed by festooning, margin sealing, and finalizing the overnight at room temperature. The next day the fin of
surface texture. The cast was scanned with a desktop the prosthesis was trimmed off with scissors after it had
scanner, exported into STL format, and superimposed been removed from the cast. The nasal prosthesis was
with the origin cast contour to differentiate the wax evaluated on her to confirm the improved airway, and
prosthesis portion digitally in another CAD software extrinsic staining was performed followed by the surface
program (Meshmixer; Autodesk). A lid was designed in sealing process. She was satisfied with the outcome on
the same software program to adapt to the existing cast both esthetic and functional counts; the prosthesis had
on all the surfaces except the waxed region; the space sufficient retention from the nasal dilator portion (Fig. 8).
was preserved between the lid and cast as per the con- The instructions for maintenance and care were pro-
tour of the wax prosthesis. The lid was printed in another vided, as well as the silicone-based prosthetic adhesive
3D printing machine (Form 2; Formlabs) with a different (B-401; Factor II). The adhesive was introduced and given
color of light-polymerized engineering resin (Grey Pro to her in case better margin adaption was required.
Resin; Formlabs) for differentiation purpose (Fig. 7). The She returned 1 month after the prosthesis was
pink wax was then removed from the cast and the frame. delivered for follow-up and she expressed satisfaction
The silicone primer (Gold Primer; Factor II) was with the prosthesis. Further follow-up sequences have
applied to the dilator frame and allowed to air-dry for 30 been scheduled by either the otolaryngologist or the

Chen et al THE JOURNAL OF PROSTHETIC DENTISTRY

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Figure 6. Wax evaluation stage.

maxillofacial prosthetic clinic to monitor the treatment

outcome.

DISCUSSION
A prosthetic rehabilitation of the nasal region will not
compromise the airway because of hollowing the intaglio
surface and trimming the orifices of the nares.10,11 To
further expand the airway, a nasal dilator design may be
considered. A hollow resin appliance, an intranasal
splint, has been described in previous article to support Figure 7. Printed lid. A, Separated. B, Assembled.
collapsed alae, also expanding nasal vestibules12; how-
ever, to hollow the splint can sometimes be challenging
when the lumen takes a tortuous path. Finger springs virtually in the software and fabricate a prototype for
may be incorporated if the lumen of the splint is small evaluation; however, the available printable wax was
and if continuous expansion against the scar tissue is mainly designed for framework casting purposes with a
needed.12 higher melting temperature, thus the use of the lost wax
In the current clinical report, digital technology was technique by boiling water in the later stage was not
partially incorporated into the prosthetic rehabilitation possible. Although other prototype materials such as
process to fabricate a nasal prosthesis with an internal resins could be used, these might complicate the process
nasal dilator design. By scanning the impression, a digital of the evaluation stage especially if it could not be shaped
cast could be created. This facilitated designing the and added clinically and immediately. Finally, the med-
dilator frame directly without the difficulty of hollowing ical-grade silicone could not be printed or milled;
it; in addition, a flexible material was selected to serve as furthermore, the intrinsic and extrinsic staining required
the springs to continuously dilate the nostril in the manual work to accomplish. The nature of the fabrication
approach. The cast could then be printed out in the process in maxillofacial prosthetics limits or slows its
physical form for the conventional workflow in the development into a fully digital workflow, more so than
waxing and wax evaluation processes. The lid was in conventional restorative dentistry.13
designed and printed to accurately retrofit the existing The software and interface used to aid in the fabri-
cast to facilitate future silicone processing. By using a cation of these maxillofacial prosthetics were often
stoneless approach, the definitive mold could be dupli- designed for typical dental purposes, which made the
cated and stored more easily than with a traditional designing process more complicated and required more
gypsum mold. originality. The dilator frame in the current report was
However, some of the steps in this process still could designed with the removable partial denture module in
not be fully digitalized. As the impression required the the dental CAD software. As the demand for a digital
nostril to be in the expanded condition, a facial scan approach into maxillofacial rehabilitation increases, more
could not be used as it would not be in physical contact support from the software designer or manufacturer will
with the tissues to move them in the dilated direction. be necessary to reduce the working time and further
Moreover, it was possible to design the nasal contour enhance the digitalization process.

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Figure 8. Definitive prosthesis. A, Intaglio surface. B, Facial view.

A possible disadvantage of the described workflow 5. Sundaram RK, Viswambaran M, Dhiman RK. Rehabilitation of a case of
partial rhinectomy with silicone nasal prosthesis. Med J Armed Forces India
include the room temperature processing of the silicone 2015;71:S29-31.
because of the concern of high temperature toward the 6. Straub JM, New J, Hamilton CD, Lominska C, Shnayder Y, Thomas SM.
Radiation-induced fibrosis: mechanisms and implications for therapy.
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to 12-hour polymerization time was necessary for the 7. Gelardi M, Porro G, Sterlicchio B, Quaranta N, Ciprandi G; Group On
Sonoring IS. Internal and external nasal dilatator in patients who snore: a
medical-grade silicone used. Printed cast and lid mate- comparison in clinical practice. Acta Biomed 2019;90(2-S).
rials that can tolerate high temperature without inter- 8. Kent M. The Oxford Dictionary of Sports Science & Medicine: nasal dilator
[internet]. 3rd ed. Oxford (UK): Oxford University Press; 2007. Available at:
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future. 0001/acref-9780198568506-e-4608?rskey=KB77fH. Accessed May 20, 2020.
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Airway restriction may happen as a complication of dimethylsiloxane facial prostheses using anatomic undercuts. J Prosthet Dent
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12. Seals RR Jr, Bohnenkamp LG, Parel SM. Intranasal prostheses, splints, and
surrounding tissues of the affected nostril. By using stents. J Prosthet Dent 1988;60:595-601.
digital technology, a custom internal nasal dilator was 13. Beumer J, Marunick MT, Esposito SJ. Maxillofacial rehabilitation: prostho-
fabricated using flexible partial denture material. This dontic and surgical management of cancer-related, acquired, and congenital
defects of the head and neck. 3rd ed. Chicago: Quintessence Publishing USA;
milled dilator was incorporated into the partial nasal 2011. p. 357-8.
prosthesis to serve the patient both esthetically and Corresponding author:
functionally. Dr Po-Hsu Chen
Department of Restorative Sciences
University of Alabama at Birmingham School of Dentistry
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Chen et al THE JOURNAL OF PROSTHETIC DENTISTRY