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Assessment of in vitro cytotoxicity of four RTV-silicone elastomers used for maxillo-facial prostheses.

The cytotoxic potential of four different and potentially interesting RTV-silicones was evaluated using an in vitro cell culture technique. Both human epithelial cells and mouse fibroblasts were used in this study and the results indicate that all materials tested were cytotoxic. Treating the surface of the discs with talc appeared to decrease the cytotoxic effects of the materials.

Animals↗

Extra-oral prosthetics: past and present.

The field of maxillofacial prosthetics is concerned with the prosthetic reconstruction of missing head and neck tissue. A prosthetic replacement of an exterior part is termed an epithesis. Beautiful examples of such prostheses were described as early as the 17th century. Often these defects were caused by war traumas or accidents. Currently, facial prostheses are usually applied in cases of defects caused by the surgical removal of tumors or congenital defects. Retention of devices has always been problematic. The contributions that implants can make to solve these problems are discussed by examining some cases.

Ear, External↗

Use of implants for prosthetic rehabilitation after cancer treatment: clinical experiences.

Treatment of patients with head and neck cancer may result in extensive intra- or extra-oral defects. Prosthetic rehabilitation often will be limited by insufficient retention and an atrophic mucosa or skin. In such cases, osseointegrated implants may offer substantially improved retention for the often complex prosthetic constructions. However, irradiation has a negative influence on the bone growth capacity and thus on osseointegration. Based on experimental studies, a recovery period of 6 to 12 months after irradiation is recommended. Because of the risk of failure and the lack of sufficient and sound scientific knowledge, clinical studies of titanium implants inserted in previously irradiated bone tissue have had varying results. This paper discusses the typical requirements of implant suprastructures for resection prostheses. Some of the patient histories and clinical management presented illustrate the possibilities of implants in the field of maxillofacial reconstruction.

Aged↗

The future of extra-oral implantology.

In this paper conclusions are drawn from the experiences of subjects presented in the previous studies in this issue. Indications for bone-anchored implants, the percutaneous passage, implant placement in irradiated tissues, and the psychosocial aspects of treatment are discussed in detail. The future of the extra-oral implantology is also discussed. There is some experience with using bone-anchored implants extra-orally, but both medical and dental staff and the patients themselves are reluctant to use them. In the future, this might change when the percutaneous passage is improved, when hyperbaric oxygen therapy is generally used, when there is more insight into all the possibilities and limitations of bone-anchored devices, and when their application is generally accepted.

Ear, External↗

Implantology for correction of cranio-facial defects with an elastomer composite and bone.

The correction of cranio-facial disfigurement in the upper part of the face is the most difficult to achieve. Various materials have been utilized and are still in use. Each has advantages and disadvantages. Autogenous bone has been used with good results, except for the unacceptable irregularities of the forehead and upper orbital region. The combination graft offers the advantages of both: the bone graft will be in contact with the dura, the periorbita and the contaminated sinuses. The polyrane implant produces a smooth and contoured forehead and immediately protects the vital structures during osteoneogenesis. Twenty-six selected patients had this technique used to correct their deformity without any incidence of major complication.

Adult↗

Post-operative re-construction of dentoalveolar tissue and the mandible and maxillae using prosthetic therapy.

OBJECTIVE: To determine the range of ablative surgery and rehabilitative procedures performed on maxillofacial structures. DESIGN: A retrospective descriptive study. SETTING: University of Nairobi Dental Teaching Hospital. SUBJECTS: Patients operated on at the institutions theatre, and followed up at the University of Nairobi Dental Teaching Hospital Oral Surgery Outpatient Clinic during the period February 1996, August 1998. RESULTS: Forty four patients underwent ablative surgery during the study period. Complete records were available for 38 patients, 27 females and 11 males aged 10 to 79 years (mean 32.6 years). Surgical procedures performed included: partial mandibulectomy, marginal mandibular resection, subtotal maxillectomy, sequestrectomy and enucleation. Six (15.8%) patients who underwent mandibular resection had rigid bone plating. Five (13.2%) patients who had maxillary involvement were given surgical obturators post-operatively with one receiving a complete denture after full recovery. A total of 22 (57.9%) patients who would have reaped benefits from prostheses therapy received none. Individual patient follow-up periods ranged from seven days for two patients who had cyst enucleation to two years for three cases with ameloblastoma, and two cases with squamous cell carcinoma. CONCLUSION: It is concluded that prosthetic rehabilitation of patients undergoing extensive surgery at the University of Nairobi Dental Teaching Hospital is largely inadequate.

Adolescent↗

Design and properties of maxillofacial prosthetic materials.

Maxillofacial reconstruction by prosthetic means is a valuable contribution that medicine offers to the public. Materials design and properties are the main problems faced by scientists in this field. Materials used for intraoral prostheses are not ideal, but they have been perfected to the point of practical use. Denture resins, gold, chromium-cobalt alloys, and porcelain are widely used and produce acceptable results in the oral cavity. In this review, the properties and performance of some polymeric materials used in maxillofacial prosthetics are discussed, and new trends in research and development are also reported.

Humans↗

Intra- and extraoral prostheses using osseointegrated implants after maxillofacial surgery.

Maxillary and orbital defects due to the resection of maxillary tumors in six cases were treated utilizing maxillofacial prostheses employing pure titanium osseointegrated implants (Brãnemark system). A total of 17 fixtures were installed in the maxillary region, and 16 achieved osseointegration. For the orbital region, nine fixtures were installed, and all fixtures integrated well. Using these fixtures as anchors, four maxillary prostheses and three orbital prostheses were set. The stability of the prostheses were improved by anchors, and the prostheses were highly satisfactory to the patients.

Adult↗

Use of a new malleable implant as a bone substitute in maxillofacial surgery.

Biocompatible osteoconductive polymer (BOP) has been used since 1979 as a substitute for bone in orthopedic surgery and neurosurgery. To date, in maxillofacial surgery, loss of bone volume as a result of either trauma or osteoporosis has been compensated for by autologous bone onlay graft or subperiosteal apposition grafts of synthetic materials. Neither of these solutions is entirely satisfactory. Autologous bone is subject to reabsorption, requiring initial overcorrection and multiple reoperations to achieve an acceptable result. Preshaped implants of Proplast, Vicryl, Gore-Tex, or silicone do not offer much flexibility, and coral granules and hydroxyapatite are difficult to handle. Finally, all foreign materials can elicit problems with tolerability. In its SP (solution/powder) form, BOP is a paste that can be molded precisely to the required shape, making it ideal for maxillofacial surgery. This study examined the long-term tolerability and facial alterations after implants of BOP in 11 patients who underwent post-trauma and cosmetic surgery.

Adult↗

Fundamental studies of maxillofacial materials: Part 1. Differential scanning calorimetric analyses of a heat-polymerized silicone.

Differential scanning calorimetry was used to evaluate the effects of polymerizing conditions and the addition of pigments for a heat-activated maxillofacial silicone (MDX 4-4515). Unpigmented specimens were examined in the starting condition and after polymerizing at 100 degrees C for 1 hour, 4 hours, and 20 hours, and specimens of four different pigmented silicones processed 1 hour at 100 degrees C were also included. The DSC scanning was performed from -150 degrees C to 200 degrees C at 10 degrees C per minute, and a strong melting-recrystallization peak at approximately -40 degrees C was found for all eight specimen groups (N = 5). Modulated differential scanning calorimetry resolved this peak into separate melting and recrystallization peaks, and confirmed the existence of a very weak glass transition peak in this silicone at approximately -125 degrees C. The mechanical properties of the MDX 4-4515 silicone appear to be dominated by melting and recrystallization, rather than the glass transition, and differences may exist in the viscoelastic and creep behavior for the unpigmented and pigmented materials.

Analysis of Variance↗

Histologic evaluation of clinically successful osseointegrated implants retrieved from irradiated bone: a report of 2 patients.

The present study described the histologic findings of 2 implants and surrounding tissues retrieved from human irradiated bone. For the treatment of a malignant tumor, 50 Gy of irradiation after implant placement and 60 Gy of irradiation before implant placement were provided for patients 1 and 2, respectively. In patient 1, the implant and surrounding tissues were removed from the frontal bone 24 months after implant placement because of the patient's death from a tumor recurrence. In patient 2, the implant and surrounding tissue were removed from a maxillectomy site 26 months after implant placement because of tumor recurrence. In each patient, new bone formation surrounding the implants was observed. The ratio of direct bone-implant contact along the threaded implant surface was 61.3% in patient 1 and 69.0% in patient 2. The ratio of the area occupied by mineralized bone in each thread was 75.8% in patient 1 and 81.2% in patient 2. These results indicate the potential of irradiated bone to achieve osseointegration of titanium implants.

Adenocarcinoma↗