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Results for “Maxillofacial Prosthesis”

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Single-dose antibiotic prophylaxis in maxillofacial surgery.

The clinical efficacy of short-term antimicrobial prophylaxis with either one shot of ceftriaxone (1 g) or a course of 3 injections of a fixed combination of mezlocillin (2 g) and oxacillin (1 g) administered over 24 h was studied in a prospective randomized clinical study of 100 patients undergoing elective maxillofacial surgery. Tissue and plasma concentrations of the antibiotics were determined by high-pressure liquid chromatography in 6 tumor surgery patients from each treatment group. Statistical analysis showed the treatment group to be comparable both demographically and with respect to the types of surgery performed and the durations of the procedures. Only 1 patient in each group developed a postoperative wound infection. It is concluded that 1 g ceftriaxone given 30 min preoperatively meets the pharmacokinetic requirements for perioperative antimicrobial prophylaxis in maxillofacial surgery.

Adult↗

Integration of titanium implants in irradiated bone. Histologic and clinical study.

Nine patients who had undergone combined surgical and radiologic treatment for malignant tumors had skin-penetrating titanium implants inserted in the bone tissue in the treated region at various time intervals after irradiation. The absorbed dose to the implant region varied between 25 and 86 Gy normalized to five fractions of 2.0 Gy/wk, according to the cumulative radiation effect formula. The time interval between irradiation and fixture insertion varied from 9 months to 37 years. Of the 35 fixtures installed, only five were lost because of lack of osseointegration. The follow-up time from implant insertion ranged from 15 to 44 months.

Ear Neoplasms↗

A new Ti-5Ag alloy for customized prostheses by three-dimensional printing (3DP).

Three important considerations in the fabrication of customized cranio-maxillofacial prostheses are geometric precision, material strength, and biocompatibility. Three-dimensional printing (3DP) is a rapid part-fabrication process that can produce complex parts with high precision. The aim of this study was to design, synthesize by 3DP, and characterize a new Ti-5Ag (wt%) alloy. Silver nitrate was found to be an appropriate inorganic binder for the Ti powder-based skeleton, and the optimum sintering parameters for full densification were determined. The hardness of the Ti-5Ag alloy was shown to be much higher than that of a pure titanium sample. Potentiodynamic measurements, carried out in saline solution at body temperature, showed that the Ti-5Ag alloy had good passivation behavior, similar to that of pure titanium. It is concluded that the Ti-Ag system may be suitable for fabrication of customized prostheses by 3DP.

Alloys↗

Dynamic mechanical properties of maxillofacial materials.

Six maxillofacial materials were evaluated by determining their dynamic properties with use of a Goodyear Vibrotester. The dynamic modulus, internal friction, and dynamic resilience were measured for all materials over a temperature range of -15 to 37 C. The dynamic modulus ranged from 11.1 to 124.8 kg/cm2 and the dynamic resilience varied from 1.1 to 63.5%.

Chemical Phenomena↗

Polyurethane elastomers as maxillofacial prosthetic materials.

A series of polyurethane elastomers based on an aliphatic diisocyanate and a polyether macroglycol was polymerized with various cross-link densities and OH/NCO ratios. Stoichiometries yielding between 8,600 and 12,900 gm/mole/crosslink and an OH/NCO ratio of 1.1 resulted in polymers with the low modulus, yet high strength and elongation necessary for maxillofacial applications.

Butylene Glycols↗

Color stability of elastomers for maxillofacial appliances.

The color stability of polyvinyl chloride, polyurethane, and silicone polymers for maxillofacial applications was determined after accelerated aging using reflectance spectrophotometry. On the basis of color stability after accelerated aging, and ease of processing, several silicone materials were the most promising.

Color↗

Color stability of a pigmented elastomer for maxillofacial appliances.

The color stability of a series of eleven maxillofacial pigments was determined after accelerated aging using reflection spectrophotometry. The results indicate that seven of the pigments demonstrated good to excellent color stability, while four of the pigments were less promising for clinical use.

Color↗

Stain resistance of maxillofacial materials.

The resistance of three silicone and one polyvinyl chloride maxillofacial materials to staining by tea, lipstick, and disclosing solution was measured by reflectance spectrophotometry. Changes in color caused by staining were larger than changes caused by color instability of the base elastomers or pigments under conditions of accelerated aging.

Color↗

Physical properties of maxillofacial elastomers under conditions of accelerated aging.

The stability of the physical properties of various commercially available maxillofacial prosthetic materials was evaluated with the use of an accelerated aging chamber. The tensile strength, maximum percent elongation, shear strength, tear energy, and Shore A hardness were determined before and after accelerated aging. Results indicate that silicone 44210, a RTV rubber, is a promising elastomer for maxillofacial application.

Chemical Phenomena↗

Physical properties of a pigmented silicone maxillofacial material as a function of accelerated aging.

The effects of accelerated aging on a pigmented elastomer were evaluated by using a weathering chamber. Silastic 44210, a maxillofacial material with proven color and physical property stability, was chosen for pigmentation with 11 maxillofacial pigments. The values of ultimate tensile strength, maximum percent elongation, shear strength, Shore A hardness, and permanent deformation were determined for the pigmented elastomer before and after accelerated aging for 900 h. Results obtained indicate that the incorporation of 0.2% by weight of pigments can alter the physical and mechanical properties of the base elastomer. Accelerated aging had no effect on the physical properties of the pigment/elastomer combinations.

Chemical Phenomena↗

Stain removal from a silicone maxillofacial elastomer.

In this study, environmental stains were removed from maxillofacial elastomers by solvent extraction. Silastic 44210, an RTV silicone with proven color and physical property stability, was stained with lipstick, disclosing solution, and methylene blue. These stains were then removed by solvent extraction with each of four chemically dissimilar solvents, namely: toluene, benzene, 1,1,1-trichloroethane, and n-hexane. An additional series of samples was prepared with 11 maxillofacial pigments, not for staining, but for evaluation of pigment stability. Results obtained from spectrophotometric measurements before and after solvent extraction demonstrated the effectiveness of solvent extraction in removing stains, while there was little or no change in the color of the pigments or the base elastomer.

Chemical Phenomena↗

Stain removal from a pigmented silicone maxillofacial elastomer.

The removal of environmental stains from a pigmented maxillofacial elastomer was carried out by solvent extraction under network swelling. Silastic 44210 was pigmented with 11 maxillofacial pigments prior to staining. Samples were stained with lipstick, methylene blue, and disclosing solution. These stains were then removed by solvent extraction with 1,1,1-trichloroethane. Color parameter measurements both before and after staining and after solvent extraction demonstrated the effectiveness of removing these stains by solvent extraction while causing little or no change in the color of the pigmented samples.

Color↗

Cigarette staining and cleaning of a maxillofacial silicone.

In this study, a maxillofacial silicone elastomer was stained with cigarette smoke. The stain was then removed by solvent extraction using 1,1,1-trichloroethane. The cigarette smoke produced large color changes in the elastomer as measured from spectrophotometric reflectance curves. The solvent was totally effective in removing the cigarette stain without changing the color of the silicone base.

Color↗

The color accuracy of the Kubelka-Munk theory for various colorants in maxillofacial prosthetic material.

The reflectance model developed by Kubelka and Munk was evaluated for agreement in color prediction of thick pigmented samples and for linearity of optical absorption and scattering coefficients with concentration of colorant in maxillofacial elastomer. The colorants tested were generic opacifiers, dry mineral earth pigments, and fibrous colorants. Significant linear relationships were commonly found between the optical coefficients and the concentration of the colorants. These relationships indicated occasional optical interaction between the colorants and the elastomer. Color differences between theoretical and observed colors of the thick samples averaged 2.96, 3.47, and 1.60 for the opacifiers, mineral earth pigments, and fibrous colorants, respectively, when measured using the CIELAB uniform-color space. The agreement between theoretical and observed colors was significantly closer for the fibrous colorants than for the dry mineral earth pigments of the same labeled color.

Color↗