Suggested techniques for producing a partial prosthesis from silicone rubber.

Introduction: At present, the researchers are targeted to improve and increase the biocompatibility of dental materials that are in direct contact with biological tissues. The biocompatibility of the dental materials that contact the tissues of the oral cavity present relevance for the patient, clinician, dental technician, and manufacturer. Aim of the study: The aim of this study was represented by the comparative research regarding the comfort of the patients wearing removable partial prostheses with clasps made of wire and flexible polymers. Material and Methods. Patients wearing partial dentures from Meliodent heat-cured acrylic resins with wipla wire clasps, flexible partial dentures made from Valplast and dentures with clasps of CuSil silicone rubber participated in this study. The research was performed on 3 groups, of 8 patients each, in which comfort levels (according to 5 criteria) were determined, after 6, 12, 18, respectively 24 months of the partial removable prostheses insertion in the oral cavity. Results. Presence of decubitus lesions of the oral mucosa in the clasps areas was noticed mostly in the Valplast polyamide dentures (37.5%), existence of color changes at the base of prostheses and of clasps area appeared in 37.5% of the third group (CuSil PAD) patients, no patient included in the study presented allergic reactions and at the third and fourth recall, only 1 patient of all groups complained of unpleasant taste in the oral cavity. Conclusion. The removable prosthetic restorations with clasps made of flexible polymers and CuSil gaskets of silicone rubber, although initially much more comfortable and therefore much better accepted by patients, after two years were no longer active, could not be activated and necessited technical restorations, compared to those made of wipla wire clasps, which were activated with pliers, or, in the case of fracture, were replaced by the technician in the dental laboratory.

The clinical application of silicone rubber is based on a high degree of tolerance by the body and the lack of foreign-body reaction. This material has been used in plastic correction of facial bony defects and nasal deformities, soft tissue augmentation, tubes and valves for the relief of hydrocephalus, heart valve prostheses, and in repair of meningoceles and defects of the dura mater. Silicone rubber has been considered an ideal substitute for soft tissues. 1 It appears to be inert and nonirritating, to cause minimal fibrous tissue formation, and no foreign-body reaction. In this experiment Dacron, calendered with Silastic of 0.007 in. thickness—a fine, nonporous, resistant fabric—was studied, first to observe its fate as a partial pericardial prosthesis, and second to show the resultant neighboring tissue reaction in surgically produced pericardial defects. In a previous experiment, 2 the lack of peritoneal adhesion to a tubular drain and the occasional

Agar has been used for a number of years in the preparation of elastic duplicating materials. These duplicating materials have been used mainly in partial denture prosthesis for the preparation of a duplicate refectory cast of the original stone cast of the patient's mouth. Since moderately large quantities of duplicating materials are used in these procedures, the low cost and reversibility of the agar materials are a definite advantage. The mercaptan and silicone rubber elastic impression materials have not been used extensively in duplicating procedures because of their high cost and the fact that these materials, once set, are irreversible. Recently, a plastic duplicating material has been developed which is a reversible polyvinyl chloride plastic gel. Because of its chemical and physical nature, this material has elastic properties somewhat different from the agar compounds. The agar duplicating compounds are composed primarily of agar and water but may also contain borax to increase the strength, salts to accelerate the setting of the investment, and other ingredients. Cellulose fibers, waxes, and fillers, which may be found in impression compounds, generally are omitted from duplicating compounds, since the duplicating materials are often stored in the sol state for extended periods and these ingredients tend to separate under this condition of storage. Since the duplicating compounds may be stored at temperatures of 130°-150° F., their resistance to thermal degradation is an important property. The basic composition of the agar impression compounds is much the same as for the agar duplicating compounds. The principal difference is that the impression compounds may contain 10-15 per cent agar, while the duplicating materials may contain only 5 per cent agar and, as just indicated, need not contain waxes, fillers, and other modifiers common to impression materials. In fact, agar impression materials have been used as duplicating compounds by simply diluting the impression material with an equal amount of water. The properties of the agar impression compounds have been studied by numerous investigators. Skinner and Kern' determined the linear-dimensional changes in air and subsequently in water of various agar impression compounds. They also measured the compressive properties of proportional limit, maximum flexibility, and crushing strength, as well as the plastic flow properties of these agar materials. Paffenbarger2 reported the compressive properties of strength, deformation, set, and stiffness of a number of agar compounds. The temperature of gel formation and the impression-

Complete or partial fingers are the most commonly encountered forms of partial hand losses. Though finger amputations are commonly due to traumatic injuries, digit loss may also be attributed to congenital malformations and disease. Irrespective of the etiology, the loss of a finger has a considerable functional and psychological impact on an individual. In order to alleviate these problems, partial or complete finger prosthesis may be fabricated. This clinical report portrays a method to fabricate silicone rubber prosthesis for a patient who has a partial finger loss caused due to trauma.

Partial or complete fingers are the most commonly encountered forms of partial hand losses. Although finger amputations are commonly due to traumatic injuries, digit loss may also be attributed to congenital malformations and disease. Irrespective of the etiology, the loss of a finger has a considerable functional and psychological impact on an individual. Maxillofacial prostheses replace the lost body parts using the silicone materials to alleviate these problems, and partial or complete finger prosthesis may be fabricated. This clinical report portrays a method to fabricate silicone rubber prosthesis for a patient who had a partial amputated thumb caused due to trauma. These prostheses support the patients physically as well as psychologically, thus enhancing their confidence and social acceptance.