Nasal prosthesis

Figure 21.11 Self-cured polymethyl methacrylate infrastructure for a nasal prosthesis.

Figure 21.12 An implant-supported nasal prosthesis was made with PDMS elastomeric material.

A 56-year-old chronic intranasal cocaine abuser with a visible nasal defect presented with a hole in the roof of his mouth. He had been reportedly drug free for 2 weeks. He had an oronasal fistula with adjacent black necrotic areas and erosive destruction of the nasal septum, turbinates, and antrum, with mucoperiosteal thickening of the sphenoid and maxillary sinuses. Treatment included antibiotics and a prosthesis plate construction... 

Both allergic and irritant mechanisms have been proposed as explanations for nasal symptoms. Measures that have successfully been used include nasal swabs (eosinophils), nasal lavage or biopsy, acoustic rhinometry (nasal volume), anterior and posterior rhinomanometry (plethysmography), and measures of nasal hyperreactivity (visual, using a dental prosthesis as a head fixative, and using an ear surgery microscope to measure distances and swelling). 

There was a large defect of the central hard palate, and the entire soft palate and the inferior nasal septum, vomer, and inferior nasal turbinates were absent. Treatment focused on treating the infection, extracting all the teeth, and providing a prosthesis to correct the defects in the palate, in order to restore speech, swallowing, and masticatory function. 

The tensile strength of the silicone elastomer ensures an overall strength of the material. Moreover, a high elongation at break is desirable, especially when peeling a nasal or eye prosthesis from the facial tissue. 

Another problem that has become evident with the use of these materials, is a black discoloration of the inside surfaces of some nasal prostheses after they have been worn for a period of time. As these areas increase in size, the color value of the prosthesis decreases until it no longer matches the patienfs skin color and must be remade. A hygiene problem also arises, because the stained areas are visually unappeahng and cannot easily be removed from the surface of the sihcone. This problem is limited to nasal prostheses, which are more susceptible to contamination because of the high volume of moist air and secretions that constantly pass through the nasal apertures. This discoloration was also attributed to fungal growth [59]. 

Distribution of 35 facial prostheses were reported by Leonard et al. [19] of these, 12 were congenital, and consequently 8 were traumatic, 8 were resected neoplasms and 7 were infectious defect prostheses. Karakoca et al. [20] reported the 60 facial prostheses as 32 auricular, 25 orbital and 13 nasal. Also, Hatamleh et al. [21] studied the types of facial prostheses that were constructed by maxillofacial prosthodontists and technologists as an alternative treatment when mctxiUofacial defects cannot be fulfilled surgically. In that study, 1193 prostheses were recorded and were followed. Of these, 42% of them were ocular, 31% were auricular, 13% were orbital, 12% were nasal and 1% was composite, that is, more than one facial prosthesis. 

Toljanic et al. [32] reported the survival rates of the facial implants in a retrospective study. Implant failure rate in the orbital region was found to be 23% after 5 years and 42% after 10 years. Charpiot et al. [30] found the ossointegra-tion rate of 142 implants used for 51 facial prostheses was 95.7%. Leonard et al. [19] reported that implant failure was observed for 2 of the 3 implants placed to support a nasal epithesis in a patient with hepatitis C virus who also had serious periodontal disease and had experienced a post-infective necrosis of the nose after a liver transplantation. An implant failure was also observed in a diabetic patient with an extensive midfacial defect due to a mycotic infection, but it did not compromise the retention of the prosthesis. 

Akman et al. [15] reported the treatment of a patient with osseointegrated extraoral implants supporting a framework retainer and acrylic resin mesostructures and a large silicone midfacial prosthesis. A metal framework was used to splint the implants together and provided satisfactory retention for the facial prosthesis. There were several case reports about the implant-retained auricular prostheses [2, 3, 29] and the implant-retained nasal prostheses [13,28,31]. 

The water absorption of a facial prosthesis is important since they may absorb saliva, sweat and/or nasal secretions from the surrounding tissue and also during washing the prosthesis in water. Any absorbed water may affect the physical properties and subsequently influence the color matching to the surrounding facial tissue [57]. 

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