Facial Implants

Implant-supported facial prostheses are well studied md precisely described in related Kteratme md the osseointegrated implants cue presented is the most reliable retention element for the faded prostheses in the recent studies, even though there are stiff indications for noninvcisive methods such as medical adhesives [2,4,10,12-14,27-34]. 

Maintaining a reliable and long-lasting osseointegration in between the implant-bone interface is the first step of the success of any bone-anchored facial prosthesis. Of 142 implants that were used on 50 patients, osseointegration was observed in 95.7% of nonirradiated patients and 81.6% in irradiated ones, presenting radiotherapy as a potential factor which reduces the rate of osseointegration [30]. 

Osseointegrated implants are used in different regions of the face to fix a facial prosthesis. However, they should correspond to the requirements of the facial prosthesis. 

Placing of the implants and production of the PDMS prosthesis are described in detail in case reports [3, 13, 27, 29]. Conventionally, mastoid bone is known as the most suitable implant site for an auricular prosthesis. Locations of the implants may be easily planned. According to the analog watch projected to the right ew is to superimpose the meatus onto the center, implants should be located between the 9 o clock and 11 o clock position at the distance of 2 cm from the meatus [1, 3]. This location roughly corresponds with the antihehx, and thus provides sufficient space for the abutments of the auricular prosthesis. The sufficient implant number was reported as 2 for the bcu-retained auricular prostheses and 3 for the magnet-retcuned ones [Ij. 

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. 

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In The Netherlands the firm Cam Implants in Leiden manufactures a series of implants on the basis of HA, among which bio-active coatings on orthopaedic and dental implants, implants for the small bones of the middle ear, which are made of dense ceramics, porous ceramics for the middle ear and jaw and facial implants. The latter are e.g. small blocks to fill holes resulting from the removal of cysts and tumours. 

Biomedical applications of silicones are numerous, while silicon-based oils find important applications as lubricants in medicine, in aeronautical domains, or in the automobile and petroleum industries. Silicone elastomers are used as medical tubings, catheters, prostheses and mammary and facial implants. 

Initially the implants were intended mainly to replace affected (i.e., broken bones, heart, vein, liver, pancrease) or malfunctioning body p>arts which people cannot live without. Subsequently, the industry of implants developed fast and now there are implants which are used for reconstructing and aesthetic purposes such as breast implants, bone facial implants and skin implants. According to the type of replaced tissue, they are divided into hard and soft implants. Hard tissue implants are usually made of metals or ceramics (bone implants, dental sealant, and joints) while soft tissue implants are made of polymers (blood vessels, skin, plastic surgery). 

Polyethylene Hip, tendon/ligament implants and facial implants... 

Surgical retention is provided by surgically created retention elements such as skin-penetrating osseointegrated implants [1] (Figure 21.1). Numerous studies were found in the literature about facial implants [3, 4, 14, 15, 19, 20, 27-32]. Burn defects may also be rehabilitated with the facial prostheses anchored with osseointegrated implants [2]. Leonard et al. [19] reported 111 implants that have been positioned to retain 35 facial prostheses. They were placed to support 21 auricular (bilateral in 2 cases), 4 orbital, 8 nasal, and 2 complex midfacial prostheses. Charpiot et al. [30] reported 142 implants that have been placed for 51 facial prostheses. Hatamleh et al. [21] performed a questionnaire study to observe the preferences of maxillofacial prosthetists and technologists (MPTs) and showed that implant-retained bars are commonly preferred to retain auricular prostheses (70%). Karakoca et al. [20] evaluated 32 auricular, 25 orbital, and 13 nasal prostheses supported with implants. 

Several in vivo stuckes support the capacity of inflammation in mecUating neuroprotective and neurodegenerative properties in the nervous system. One such example is the facial nerve axotomy paracUgm in newborn rats and rabbits. In this system model, axotomized motor neurons recover coincidentally with the development of the glial response (Moran and Graeber, 2004). It was also shown that a month after implantation of... 

Suzuki K, Aoki M, Kawana S, Hyakusoku H, Miyazawa S. Metastatic silicone granuloma lupus miliaris disseminatus faciei-like facial nodules and sicca complex in a silicone breast implant recipient. Arch Dermatol 2002 138(4) 537-8. 

The application of polymeric materials in medicine is a fairly specialized area with a wide range of specific applications and requirements. Although the total volume of polymers used in this application may be small compared to the annual production of polyethylene, for example, the total amount of money spent annually on prosthetic and biomedical devices exceeds 16 billion in the United States alone. These applications include over a million dentures, nearly a half billion dental fillings, about six million contact lenses, over a million replacement joints (hip, knee, finger, etc.), about a half million plastic surgery operations (breast prosthesis, facial reconstruction, etc.), over 25,000 heart valves, and 60,000 pacemaker implantations. In addition, over AO,000 patients are on hemodialysis units (artificial kidney) on a regular basis, and over 90,000 coronary bypass operations (often using synthetic polymers) are performed each year (]J. 

Hyaluronic acid improves elasticity and viscosity of synovial fluid. It is indicated in the treatment of pain of osteoarthritis of the knee in patients who have failed to respond adequately to conservative nonpharmacologic therapy and to simple analgesics (e.g., acetaminophen) and mid to deep dermal implantation for correction of moderate to severe facial wrinkles and folds, such as nasolabial folds (Restylane). 

Poly-L-Lactic acid is a physical adjunct that is an injectable implant of microparticles of poly-L-lactic acid. It is indicated in restoration and/or correction of signs of facial fat loss (lipoatrophy) in people with HIV. 

Rubin, J. P. et al.. Complications and toxicities of implantable biomaterials used in facial reconstructive and aesthetic surgery a comprehensive review of the literature. Blast. Reconstr. Surg., 100, 1336, 1997. 

Plasticity. In JR, we implanted area 4, hand representation, as determined by the functional MRI. We realized that he was moving facial muscles, specifically eyebrow movements, to produce neural activations. We preferred of course that he use neural activity that was not related to face or other residual movements. We asked JR not to use face movements of any kind during cursor driving. He appeared to comply with this request. To ensure that he did not move, we placed electrodes over his eyebrows to measure EMG activity. This activity would have driven the cursor in the vertical direction. This would have upset his performance in a task that required him to move horizontally to hit icons. Thus he had to maintain relaxation of his eyebrow muscles. The neural activity that drove the cursor is shown in Figure 32.7 with the target icon entry point on the right above, and the EMG activity shown below over a 10-sec timebase. Note the neural bursts that are not accompanied by the EMG activity. 

There are two types of maxillofacial implants extraoral and intraoral. The former deals with the use of artificial substitutes for reconstructing defective regions in the maxilla, mandible, and face. Useful polymeric materials for extraoral implants require (1) match of color and texture with those of the patient (2) mechanical and chemical stability (i.e., material should not creep or change color or irritate skin) and (3) ease of fabrication. Copolymers of vinyl chloride and vinyl acetate (with 5 to 20% acetate), polymethyl methacrylate, silicones, and polyurethane rubbers are currently used. Intraoral implants are used for repairing maxilla, mandibular, and facial bone defects. Material requirements for the intraoral... 

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