Implant-retained auricular prostheses: a clinical challenge

Abstract

Microtia, malformation, deformity, and partial or complete loss of the pinna may be due to various congenital or acquired factors. In adult patients, surgical reconstruction of the missing pinna is difficult and the results are often far from satisfactory. An implant-retained auricular prosthesis is a suitable alternative. A retrospective study of eight patients treated with implant-retained auricular prostheses was performed. For each missing pinna, three titanium implants were placed in the temporal bone. After 6 months of osseointegration, the implants were loaded. Four cases were rehabilitated with a magnet-retained prosthesis and the remaining four with a bar and clip retained prosthesis. There were six male and two female patients with an average age of 30.62 years. Seven patients had unilateral absence of the pinna and one had bilateral absence. The loss was due to trauma in four patients and to burn in one patient, and three had congenital absence. A total 27 implants were placed, 12 on the right side and 15 on the left. The average post-rehabilitation follow-up was 21 months. Peri-implant tissue reactions were observed at two sites. The implant-retained auricular prosthesis is an alternative treatment approach with good retention and patient satisfaction. Long-term follow-up is required to assess delayed complications.

The auricle, or pinna, is an integral part of the external ear. It consists of single auricular cartilage, a thin layer of connective tissue, and skin. The primary role of the pinna is to catch sound waves. It also plays an important role in facial aesthetics. There are anatomical variations in the shape and size of the pinna. Microtia (small ear), malformation, deformity, and partial or complete loss of the auricle may be due to various congenital or acquired factors. Congenital malformations may be syndromic, as in cases of otofacial, craniofacial, and otocervical dysostosis, or non-syndromic. The acquired causes are human and dog bites, motor vehicle accidents, burns, cancer, and frostbite.

Subtotal and total loss of the pinna is a difficult clinical situation for surgical reconstruction. For the patient, the results are often far from satisfactory. An auricular prosthesis is a relatively simpler option. Prior to the introduction of craniofacial implants for implant-retained maxillofacial prostheses, the standard of care for maxillofacial prosthetic treatment was either an adhesive-retained or a mechanically retained auricular prosthesis. The adhesive-retained prosthesis proved to be less than optimal regarding the provision of predictable retention and often created challenges in prosthesis orientation when positioned by the patient. The implant-retained auricular prosthesis is an alternative treatment approach that has undergone improvement and provides more predictable retention than prostheses that are retained with adhesive. The purpose of this article is to highlight the challenges in implant placement and fabrication, and the limitations of implant-retained auricular prostheses.

Materials and methods

This retrospective study was conducted in the department of dental surgery of the study medical college in Pune, India, from January 2010 to December 2014. All patients with a missing pinna who were referred from the ENT and reconstructive surgery department for implant-retained prosthetic rehabilitation were eligible for inclusion in the study. Male and female patients who were above the age of 18 years, who had a congenital absence, acquired loss, or a malformed ear, and who were without any systemic illness, were identified ( Fig. 1 ). Only those patients who completed a minimum follow-up period of 18 months were included.

Fig. 1
Pre-treatment photograph.

Only patients with diseases of the temporal bone and mastoid process, an ear infection, a previous history of mastoid surgery, or a systemic illness were excluded. A total of 10 patients were rehabilitated during the study period, but only nine fulfilled the above requisite inclusion criteria. One patient in the selected group was lost during the follow-up period due to relocation of residence and hence was not included in the study. Patient data are presented in Table 1 .

Table 1
Patient data.
Case No. Age, years Sex Side Number of implants Aetiology Follow-up period, months
1 25 M Right 3 Congenital 54
2 26 F Left 3 Congenital 51
3 32 M Left 3 Trauma 49
4 41 M Left 3 Trauma 42
5 22 F Bilateral 3 + 3 Burn 38
6 26 M Right 3 Trauma 29
7 40 M Left 3 Trauma 22
8 33 M Right 3 Congenital 18

M, male; F, female.

Patient evaluation included a computed tomography (CT) scan to measure the thickness of available bone in the mastoid region and ENT and neurosurgical consultations. A facial casting was made by making an impression with irreversible hydrocolloid impression material and pouring with dental stone. For accurate positioning, a face-bow orientation was used wherein the earpiece, the maxillary and mandibular dentition, and the infraorbital point acted as three fixed reference points, while the earpiece on the side of the missing ear gave the location of the opening of the external auditory meatus. A template of clear polymethyl methacrylate was fabricated and three markings were made corresponding to 7 a.m., 9 a.m., and 11 a.m. clock positions, which were about 10–15 mm from the external acoustic meatus and equidistant from each other. These positions were then assessed clinically and radiographically using a CT scan for thickness of available bone. A straight fissure bur was used to prepare appropriate holes in the area corresponding to the size of the implant drill. TIXOS laser sintered titanium implants of 5 mm in diameter and 5–7 mm in length were used (Leader Italia Srl, Milan, Italy). The abutments were inserted simultaneously during the surgical procedure.

Prior to the surgical procedure, about 2.5 cm of temporal shaving was carried out. All cases were operated on under general anaesthesia. Vaseline gauze was packed into the external auditory meatus. A curvilinear incision line was marked extending 1.5 cm into the hair-bearing area. Adrenaline in 1:100,000 dilutions was injected along the proposed line of incision. The surgical stent was used to mark the position of the implants on the skin. A full thickness flap was raised to expose the mastoid process and adjoining area. A 2-mm diameter tissue punch was used to remove soft tissue at the marked points to expose the bone. Osteotomies were carried out to the required dimensions in a sequential manner under normal saline cooling, as per the manufacturer’s instructions. A torque wrench was then used to place the implants into their final positions and primary stability was assessed ( Fig. 2 ). The inner side of the flap was adequately thinned for better adaptation. The pre-casted abutments were placed through the punch holes ( Fig. 3 ). Haemostasis was achieved, the wound was sutured, and a pressure dressing was applied. Postoperative antibiotics and analgesics were given as per the institutional protocol and healing was uneventful. The patients were reviewed every month and the implants were left unloaded for 6 months to allow osseointegration. A lateral view radiograph of the skull was taken to evaluate the surrounding bone ( Fig. 4 ).

Jan 16, 2018 | Posted by in Oral and Maxillofacial Surgery | Comments Off on Implant-retained auricular prostheses: a clinical challenge
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