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Case report
Lobe of sound: prosthetic rehabilitation of partial auriculectomy defect
  1. Ashmi Sebastian,
  2. Sanjayagouda B Patil,
  3. Anantha N Sundararajan and
  4. Lakkappa S Ganiger
  1. Department of Prosthodontics, Sri Hasanamba Dental College and Hospital, Hassan, Karnataka, India
  1. Correspondence to Dr Sanjayagouda B Patil; sbpatilmanu{at}gmail.com

Abstract

Loss of facial organs in an individual may be due to congenital anomalies or acquired causes. The missing parts of the face like ear, eyes and nose are considered as maxillofacial defects that can be rehabilitated by a prosthesis and/or cosmetic surgeries. This frontier of science has developed into a more reliable and predictable process due to the ever-increasing development of materials and equipments used in this procedure. The fabrication of an ear prosthesis is considered by many prosthetists to be one of the most difficult replacements in maxillofacial reconstruction. The severe undercuts and pronounced convolutions of the ear present a challenge in simulating a naturally proportioned prosthesis. Proper assessment of the disfigured facial organs and a feasible approach to rehabilitating them has for long been the target of clinical maxillofacial prosthodontics. This report describes a simple and engrossing technique to rehabilitate a patient with a partial auricular defect in the most aesthetic and economical manner using medical-grade room temperature vulcanising silicone.

  • dentistry and oral medicine
  • ear
  • nose and throat/otolaryngology
  • rehabilitation medicine

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Background

Maxillofacial prosthodontics involves the rehabilitation of patients with defects or disabilities that are present congenitally or acquired due to disease or trauma. Prostheses are often needed to replace missing areas of bone and/or tissues and restore oral functions such as swallowing, speech,and chewing. In other instances, a maxillofacial prosthesis may be indicated for cosmetic and psychosocial reasons.1 Prosthetic ears are created for patients with microtia and those who have ears removed due to cancer or trauma.

The diverse treatment options available for the prosthetic rehabilitation of defective auricle includes mechanically retained prosthesis, bio-adhesive-retained prosthesis, implant retained and, the recently developed rapid prototyping2 and Computer-Aided Designing–Computer-Aided Machining (CAD-CAM) developed prosthesis.

Implant-retained prosthesis is currently considered as the gold standard in the prosthetic reconstruction of these structures. The success of bone-anchored auricular prostheses could be based on the patients’ acceptance and maintenance of the prosthesis.3 4 The major problem in using an implant-retained prosthesis is that the bulk of the prosthesis compromises the final cosmetic outcome. However, in patients who refuse to undergo any surgical procedures that are required for the implant placement or when surgical intervention is contraindicated, alternate means of retention needs to be considered.

Prosthetic rehabilitation without surgical intervention is advocated as an alternative as it is comparatively economical, hygienic, possible to re-evaluate and the colour, size and shape of the prosthesis can be easily manipulated by the clinician. Prosthesis for partial auriculectomy defect requires a systematic approach that accounts for not only the defect size and location but also the quality of the surrounding skin and final cosmetic result with good marginal integrity. The various convexities and concavities of the external ear coupled with concomitant differences in rigidity and elasticity account for the formidable challenge in prosthesis fabrication. Specific attention must be paid to the contralateral ear if unaffected. The reconstructed ear must match the opposite ear in orientation, size and shape in all three dimensions. The goal is to recreate an ear that is symmetric to the opposite side and as lifelike as possible.

Auricular prostheses are usually made of silicone elastomers, acrylic resin or of both. Recently, there has been immense progress in the field of maxillofacial prosthetics and the introduction of silicone-based materials has enabled the clinicians to provide quality healthcare to the patients in need.1 Silicones are being used for over 50 years in the field of craniofacial prosthetics, with desirable material properties including flexibility, biocompatibility, ability to accept intrinsic and extrinsic colourants, translucency, chemical and physical inertness, moldability and ease of cleaning.3 It is superlative to acrylic in terms of patient’s adaptation, shade matching, texture and aesthetics. Disadvantages being: it requires adhesives for retention, irritation at the involved site and requires regular recall.5 6

The function of the prosthetic ear is not just confined to cosmetic reconstruction but it also directs the sound waves into the auditory canal and maintains a proper environment for the inner ear membranes. It normally improves hearing by about 20%. It also serves a great psychological benefit in the rehabilitation of the patient’s social, physical, and mental well-being.7 8

Case presentation

A patient, aged 47 years, came to the Department of Prosthodontics, reporting of unilateral partial auricular deformity on her right side. The patient had no history of any major systemic illnesses. The patient met with a road traffic accident 1.5 years back due to which she lost a major portion of her right ear. On examination, there was a normal ear on left side with normal hearing. On the right side, there was deformed helix, antihelix, concha, antihelical fold, antitragus and lobule (figure 1). The patient had the normal hearing capacity on the right side. A prosthetic reconstruction was decided to fulfil the patient’s desire for cosmetic correction without surgery.

Figure 1

Pretreatment photograph.

Treatment

Impressions

The patient was placed in a near supine position on the dental chair. The head was rotated to her left so that the defect was presented on a horizontal plane, and the patient was draped during the impression procedure. The area around the ear was outlined with an indelible pencil. Three horizontal markings (figure 2A,B) were made on the normal ear at the junction of the helix with the side of the head as the first marking, the second at the middle of the tragus and the last one at the junction of the ear lobe with the side of the head. Similar markings were made on the defective side. The patient’s skin was boxed to the circumscribed outline with a cylindrical cover (figure 3) modified as a tray. An irreversible hydrocolloid impression was made by gently painting the material over the defective side. Care was taken so as not to compress the ear. The impression material was allowed to set and then was carefully removed and inspected for accuracy (figure 4). Type IV dental stone was mixed according to the manufacturer’s instruction and the impressions were poured to obtain the master cast (figure 5). The markings got transferred with the impression and were accurately transferred to the working cast. These coordinates are of value in obtaining the proper orientation of the defect while making the new ear form. The same procedure was done on the non-defective side.9

Figure 2

(A and B) Horizontal markings made on the normal ear and the defective ear.

Figure 3

Impression-making procedure using a cylindrical cover.

Figure 4

Alginate impression recorded of both the normal and defective ear with the markings transferred onto them.

Figure 5

Master cast of the defective and normal ear.

Wax pattern

Using a tracing paper, the outline of the left side ear along with the horizontal lines (figure 6A) was made. The defective ear’s cast was duplicated and tin foil was adapted on the cast. Wax was added over the tin foil and was shaped into a block. The thickness of the wax was established posteriorly, and at the exit angle of the ear from the cast anteriorly, by measuring the cast of the non-defective ear. The traced outline of the normal ear was reversed (figure 6B) and placed on the wax. The horizontal lines on the tracing paper were matched (figure 7) with those on the duplicated cast of the defective ear. Using a needle, holes were punched through the tracing paper (figure 8) along the outline of the patient’s ear. The paper was removed, leaving an outline of small holes that conform to the reverse outline of the patient’s non-defective ear. The entire ear is sculptured and the defective portion of the ear was removed and adapted onto the master cast of the defective ear to determine the final depth and contour (figure 9).10

Figure 6

(A and B) Tracing of normal ear and tracing reversed to obtain the outline of defective ear (mirror image). Tracing done by LSG.

Figure 7

Tracing matched with the markings on the duplicated cast. This was done by AS and SBP.

Figure 8

Holes made using a needle along the outline of the tracing. This was done by ANS and AS.

Figure 9

Wax-up of the auriculectomy defect.

Try-in procedure

The following points were checked and verified at try-in (figure 10).

  1. The fit of the prosthesis on the tissue.

  2. The correct horizontal alignment with the natural ear.

  3. The projection of the ear in relation to the side of the head.

  4. The integrity of the margins.

Investment and fabrication of mould

Final finishing of the wax pattern was performed on the cast of the defective ear. The finished pattern was then sealed on the cast model. A three-part flasking with indices (figure 11A,B) marking the interlocking of the pieces was planned. The first part was the die of the defective ear with its type II gypsum base. Indices to aid repositioning of the counterparts were made on all sides of the base. Modelling wax was used to provide support to the second pour of type II gypsum for the flasking. Sodium alginate separating media was painted and the middle part of the customised flask was poured. It was made sure that no gypsum flowed into any undercut of the wax pattern as this would cause a deformation of the pattern when removal of the middle part of the flask would be attempted. Following this, another modelling wax supported pour of type II gypsum was made covering the ventral surface of the auricular wax pattern. Dewaxing procedures in a hot water bath, using the standard directives were then carried out.9

Figure 11

(A and B)Three-part flasking with indices.

Intrinsic staining

Shade selection using intrinsic coloration procedures was decided. Intrinsic stains provided with the room temperature vulcanising (RTV) silicone was used for shade matching. The basic colours used were yellow, white, brown, purple and red (figure 12). Small amounts of the base and catalyst pastes were mixed and stains were added in increments with a constant comparison with the skin of the approximating area and the contralateral ear. Separate shades were decided on to accurately replicate different parts of the patient’s natural ear. Different shades were selected for the lobule, concha, helix and antihelix. The nearest possible simulation was attempted to be achieved by performing shade selection under different light sources, which included incandescent, fluorescent and natural sunlight sources. Packing of the tinted silicone material was carried out and the three parts of the flask were again reattached and seated carefully to ensure that all the margins were flushed together.11

Figure 12

Stains used for colouration.

The final prosthesis was then tried on the patient (figure 13). Bio-adhesive (Cosmosil) (figure 14) was then used to retain the prosthesis to the defective ear. The patient was advised to regularly clean the prosthesis using a mild sodium lauryl sulfate solution. The use of strong detergent solutions and hard brushes for cleansing the prosthesis was discouraged. She was instructed not to wear the prosthesis while sleeping as accidental pressure would result in distortion or tearing of the prosthesis.

Figure 13

Post-treatment photograph.

Figure 14

Adhesive used for retention of the prosthesis.

Outcome and follow-up

A regular follow-up and evaluation of the patient and the prosthesis were undertaken. The patient was recalled after a week, 1 month and 3 months to evaluate the overall prognosis and the maintenance of the prosthesis. It was noted that there were no eruptions, tearing or loss of colour on the prosthesis. The patient was satisfied and happy with the aesthetics and functional ability of the prosthesis as it proved a boost to her psychological well-being.

Discussion

The loss of the external ear can be either congenital or acquired. The acquired causes can be due to accidental trauma or malignant diseases. Congenital anomaly of the external ear is termed as ‘Microtia’. It includes a spectrum of deformities from grossly normal but small ear to the absence of the entire external ear. These deformities account for 3 in every 10 000 births, with bilaterally missing ears seen in fewer than 10% of all cases.12

The classification of Weerda combines the suggestions of various authors and provides an overview based on the increasing levels of deformity and the necessary interventions required13–16. This case report presents with a rehabilitation of grade II malformation according to Weerda Classification where some ear structures are extant. The patient was explained about the two primary methods of the rehabilitation of the missing portion of the ear that was either implant-retained or mechanically retained prosthesis.

Implants in the maxillofacial region have been used for the retention of auricular prostheses for many years.17 Several types and designs of osseointegrated implants have shown that these kinds of implants are safe and stable for a long term. The advantages of this technique over the adhesive retention include decreased incidence of dermatitis or allergic reactions induced by the adhesives and a more secure and predictable placement unaffected by perspiration and humidity.18 Titanium implants have been used in the temporal bone with skin-penetrating titanium abutments, in the construction of external ear episthesis.17 Long-term success of implant treatment depends on the implant number, position, orientation and stability. The use of porous implants has improved the stability and load-bearing results thus reducing the duration between fixture installation and abutment placement.19

The use of craniofacial implants for the retention of extraoral prosthesis offers excellent support and retentive abilities although implant placement in the mastoid region is a complicated process due to close proximity to intracranial structures.20 Magnet and bar-clip retention mechanisms are the two primary forms of retention used in the auricular region. The bar-clip system provides good retention for the prostheses but limits access for performing hygiene procedures and makes it difficult to insert and remove the prosthesis. Magnetic retention offers better hygiene, mechanical and aesthetic ascendancy over the bar-clip system21–25.

The patient was unwilling for an implant-retained prosthesis. Thus, the adhesive-retained prosthesis was advocated. The use of the remaining tissue of the rudimentary ear, combined with bio-adhesives provided a very conservative approach to fabricate a maxillofacial prosthesis. This provided a cosmetically acceptable means of camouflage for the patient. The substantial challenge in rehabilitating this patient was obtaining facial symmetry with the superior cosmetic result. This challenge arises because of the chances of undesirable displacement of the remnant tissue during impressions that can deprive the prosthesis of its symmetry and expose the margins. Also, colour matching between the prosthesis and the adjacent residual ear remnant is much more challenging than a case of the total auriculectomy defect.26 These challenges were negated by adhering to meticulous impression procedures and engaging tracer techniques in wax pattern fabrication. The borders of the wax pattern and the areas adjacent to the healthy tissues were left thin in order to appear natural. The colour matching was done by initially mixing the basic colours for human skin that are white, red, blue and yellow. The base tone of the skin was attained first, then the chroma of the base colour was changed as needed for the different parts of the ear. The colour matching for different parts of the ear was done to produce a lifelike prosthesis. After polymerisation, the auricular prosthesis was checked and adapted on the patient.

There are various techniques for the fabrication of an ear prosthesis: Conventional technique, shaper/tracer technique, photocopying technique, CT scanning, MRI, 3D laser scanning, computer numerically controlled (CNC) milling, rapid prototyping and stereolithography.27 Conventional technique using manually sculptured wax pattern is prone to divest the final aesthetic outcome. The fabrication of a virtual prototype uses the 3D images of the patient eliminating the need to produce a diagnostic wax pattern and stone mould. CT images can be used for surgical and prosthetic planning. Laser surface scanning in tandem with a rapid prototyping machine can be used for automated fabrication and anatomically accurate auricular prostheses.28 Optical laser scanners have been used in conjunction with a CNC milling machine to prepare a reversed model of a normal ear.29 Although digital methods are superlative, the appropriate technique to be used is dependent on patient preference, cost factors and the amount of remaining tissue.

The auricular prosthesis is required to look exactly like the opposite ear. So, we used the tracer technique to produce an immaculate replica of the unaffected ear. In this technique, the morphology of a patient’s unaffected ear in its correct spatial orientation was duplicated for the fabrication of the prosthesis. The technique uses parallel lines transferred to casts and tracing paper.10 This technique helps to annul the development of a subjective wax pattern. It is a simple procedure with less armamentarium to obtain a 3D mirror image wax pattern. The use of computer-aided designing and generating of the wax pattern gives desirable results in terms of symmetry but requires access to more expensive equipment.

Silicone is the material of choice for maxillofacial prosthesis because of its flexibility and lifelike appearance. The final prosthesis was fabricated using RTV silicone. Intrinsic stains were used for producing more stable colour30 and to enhance the aesthetics of the final prosthesis. The colours were chosen to match the patient’s own complexion and the contralateral ear, including freckles and capillaries. Extrinsic colours were added at certain areas in very minimal amounts to achieve lifelike appearance. Accelerated ageing studies and colour evaluation studies using the reflection spectrophotometer analysis have shown that intrinsic stains undergo considerably less amount of colour alteration as compared with extrinsic colouration methods.

Hardening of the RTV silicones over a period is a drawback of this material. Hot, humid conditions and contact of the material with sweat, dust, pollen and other offenders only hastens the hardening and discolouration process. Gradual hardening and discolouration take place over a period of time, but the material still remains in considerably acceptable condition for about 9–12 months. The patient was informed about this limitation of the material and instructed about its maintenance.

Bio-adhesive Cosmosil was used for the retention of the prosthesis. Sufficient retention was provided by using a very thin coating of the material. As the adhesive is not soluble in water it provides better retention for a longer duration of time as it will not dissolve when in contact with sweat. Recent advancements in digital techniques facilitate the production of mirror image of the auricular prosthesis with a high level of accuracy27 and help archive the design for future purposes. The limitation being the exorbitant rates for utilising them. Development in the field of tissue engineering has resulted in the formation of new tissue equivalents of bone and cartilage that will augment the outcome of prosthodontic rehabilitation in the future.

This case report highlights the importance of using a simple but effective technique in making an uncanny and immaculate reproduction of existing ear in the fabrication of a prosthesis for a partial auriculectomy defect. The patient was elated and satisfied at the end of receiving the prosthesis and adhered to the maintenance protocol.

Patient’s perspective

I had suffered enough through that phase of my life where I was recovering after a devastating accident. It was really tough. We were shattered after that incident. It added to the misery when the doctors who performed emergency treatment said that they had to remove a portion of my right ear as it got crushed completely and was beyond hope to be saved. It felt like another nail in the coffin. It was a really dark and gloomy period of my life to cope up with all that had happened in a blink of an eye. It took a while for me to recover from that incident and get back to my routine. I got better with my health and got back to my monotonous schedule. The portion of the ear removed healed with a scar.

The real battle had just begun. I was unable to attend social gatherings, functions or go out in public because of my unaesthetic facial appearance. It took a heavy toll on me. I cocooned myself and avoided many conventions. The few places I went to, everyone would instantly notice my missing ear portion and constantly kept asking about it. I was immune to it in the beginning but as it slowly soaked into me, I started to sulk. I lost my confidence and was conscious of it all the time. My confidence and mental health hit rock bottom. I used to try hiding it under my hair, but it was evident and I could not do it for long. I was tired of these questions fired at me about my ear. I knew I wanted to change this situation and regain my confidence.

So, I decided to consult a doctor regarding a prosthesis that can rehabilitate my missing ear portion. The doctor had directed me to go to a prosthodontist for the needful. The team of prosthodontists was compassionate and disciplined with their efforts. They explained to me all the minute procedures and the methods of rehabilitation. They did explain surgical rehabilitation using an implant or the bar-clip system. But I was reluctant to undergo any surgery, carrying the baggage from the trauma in the past. So, I decided to go ahead with prosthetic rehabilitation retained using adhesive. The team’s effort in providing support was faultless. They began by taking the impressions of my ears. They explained me about the tracer technique that was going to be used in the prosthesis fabrication. Over a few appointments, I was called for the insertion of the final prosthesis and I felt ecstatic and liberated. I was so relieved and regained my confidence. I was truly short of words and quite emotional too. All those gloomy days flashed before my eyes for a moment and I was pleased with the outcome. I am really grateful for all the care I’ve received.

Learning points

  • Partial auricular rehabilitation presents more challenges than complete rehabilitation due to the intricate details and nuances that need to be considered to culminate in a symmetrical appearance.

  • Precise planning is required to direct and achieve the rehabilitation of a patient with the partial auriculectomy defect.

  • Effective teamwork and communication between the prosthodontists and the dental laboratory technician is essential to achieve aesthetic and timely patient care.

References

Footnotes

  • Contributors AS and SBP conceived the presented idea. AS and ANS acquited past data and reviewed the available literature. ANS and LSG did the study conception and designed the entire treatment protocol. AS performed the treatment procedures. SBP supervised the findings and the treatment procedures. ANS drafted the manuscript. SBP and LSG did the critical revision. All authors read and approved upon the final manuscript.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Patient consent for publication Obtained.

  • Provenance and peer review Not commissioned; externally peer reviewed.