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Biomedical subjects

V A Chalian

Publications and source records attributed to V A Chalian.

At least 19 recordsLinked to original sources
PubMed1990

Prosthetic and surgical management of osteogenic sarcoma of the maxilla.

Maxillary surgical defects resulting from resection of oral neoplasms vary in size from small perforations of the hard and soft palate to complete removal of these structures. Osteogenic sarcoma is of unknown etiology and is a rapidly growing tumor that may produce pain, paresthesia, and anesthesia. The recommended treatment of radical resection often results in defects that produce significant orofacial disfigurement. These defects, regardless of size, present significant functional disability, with compromised esthetics, mastication, and deglutition. Restoration with a maxillary obturator prosthesis can reestablish the physical separation between oral and nasal cavities and, in soft palate defects, enable normal palatopharyngeal function. Most patients can be rehabilitated successfully with restoration of speech and swallowing to normal levels and significant improvement in appearance.

Deglutition Disorders↗
PubMed1989

Evaluation of color changes of silicone maxillofacial materials after exposure to sunlight.

A number of authors have listed the following qualities as ideal for maxillofacial material: (1) original physical and mechanical properties comparable to the human tissue that they are replacing, (2) the ability to sustain these properties during service, (3) compatibility with human tissues and the adhesives used to adhere the prostheses to tissue, and (4) the quality of being easy to process and an insensitivity to processing variables. Clinical experience has indicated that there is frequent and for the replacement of maxillofacial appliances because of rapid discoloration in the service environment and/or degradation of the physical and dynamic properties of the base elastomer. Color stability in the service environment may be the most important factor in patient acceptance of the prosthesis. The results of this study suggested that aging rather than exposure to sunlight results in most of the color changes observed in the HTV and RTV base polymers studied.

Color↗
PubMed1986

Pulp innervation after radiation therapy.

Decreased sensitivity was observed in teeth within and adjacent to an irradiated field. Mandibular teeth outside the field and distal to the irradiated mandibular nerve trunk showed an immediate decrease in sensitivity, Maxillary teeth outside the field showed a delayed decrease in sensitivity. Blood flow rates and nutrition were also related to time. Neurons are though to be relatively radio-resistant and few changes were seen histologically after radiation therapy. However, functional impairment was observed in histologically normal tissue.

Dental Pulp↗
PubMed1986

A flashing-light method for recording centric relation.

A flashing-light system has been described which provides a simple method for ensuring equalized pressure in recording the relationship of the mandible to the maxillae. The wires that protrude from the mouth do not appear to create any discomfort or distraction during the procedures. This method tends to be more comfortable than extraoral or intraoral tracing techniques. The method may create patient fear because an electrical device is used in the oral cavity. In addition, if the metal surfaces (pins and cups) are not fully coated with wax, there may be contact with adjacent soft tissue, which creates an electric sensation.

Dental Instruments↗
PubMed1986

An intraoral positive-pressure device for treatment of trismus.

Trismus is a challenging clinical problem that may result from several different causes. The dentist may choose from a wide spectrum of treatment modalities, depending on the severity of the individual case and the health and cooperation of the patient. An individual course of treatment must be planned for each patient. It is important to monitor the treatment closely for effectiveness of the therapy and to ensure the patient's compliance. Treatment should be modified as necessary, according to the patient's progress. We have described an intraoral dynamic device that may be used as part of a treatment program and that enhances patient compliance as compared to traditional extraoral devices.

Equipment Design↗
PubMed1985

Auricular compression stent.

An auricular compression stent has been developed for maintaining uniform and adjustable compression after surgical removal of earlobe keloids. The two-component device is made from heat-polymerized acrylic resin and assembled with nylon screws.

Ear Diseases↗
PubMed1985

A comparison of the physical properties of a room temperature vulcanizing silicone modified and unmodified.

RTV silicone MDX 4-4210 unmodified and modified with the addition of 5%, 10%, and 15% 360 MF 100cs was tested for the following physical properties: tensile strength, ultimate elongation (ASTM D412 die C), tear resistance (ASTM D624, die C), and Shore A Durometer hardness (ASTM D2240). The initial mechanical properties of unmodified RTV silicone were superior to those of RTV silicone modified with 5%, 10%, and 15% 360 MF except for hardness. The value for each property measured was found to decrease linearly with the amount of 360 MF added. If additional softness is desired, it can be achieved with the addition of 360 MF to RTV silicone at the expense of decreased strength, elongation, and tear resistance. Even with the addition of 15% 360 MF the values for tear resistance and elongation were in the standard range. The tensile strength of unmodified RTV silicone fell below the accepted values.

Chemical Phenomena↗
PubMed1985

Polydimethyl siloxane materials in maxillofacial prosthetics: evaluation and comparison of physical properties.

The need for more acceptable materials for use in maxillofacial prosthetics has long been recognized. In this study, the physical properties of several currently available polydimethyl siloxane materials were evaluated and compared with those of two previously tested materials. The properties chosen were tensile strength, elongation, tear strength, and hardness. These properties were chosen as indicators of the strength, flexibility, durability, and lifelike feel of the materials in clinical service. Testing procedures were intended to duplicate as nearly as possible those used by Chalian and Jones and to conform closely to ASTM specifications. In general, the physical properties of the five silicone materials tested in this study were superior to those of MDX-4-4210 and MDX-4-4514, tested previously. This superiority was particularly evident in terms of strength and elongation. Although the materials failed to demonstrate the softness of other materials, they may prove acceptable with the addition of available modifiers. Although no material was consistently superior to the others, potential merit is seen especially in Q7-4635 and SE-4524U. These materials exhibited high strength and softness and are available in one component system. Unlike the two-component addition chemistry systems, these materials have an indefinite pot life and are much more easily manipulated.(ABSTRACT TRUNCATED AT 250 WORDS)

Chemical Phenomena↗
PubMed1976

Prefabricated silicone subdermal mandibular implants: observations and problems related to their application.

Success in the use of custom-fabricated Silastic implants in patients with facial contour defects led us to utilize this method in reconstructing mandibular defects. However, mandibular reconstruction with alloplastic material is quite difficult because of the presence of continous stress and motion in that region. The evolution in the use in the use of the mandibular implant from the commercially available one to the K-wire reinforced, prefabricated, silicone implant was largely dependent on the availability of silicone and the ultimate result obtained. In the past few years, about 30 subdermal implants were inserted. Some of those implants were placed immediately into patients undergoing resection for tumor. The implant was prefabricated prior to surgery from x-ray measurements of the anticipated segment to be resected; it was then used to reconstruct the defect prior to the final closure of the operative wound. Other implants were manufactured 6-18 months after resection for tumor or for deformity as a result of trauma. The implants were used to reconstruct the facial defects and to correct the funtional abnormality, such as drooling or deviation of the affected side by the unstable mandibular segment. Patients with severe congenital malformation have soft tissue deficiency in association with their bony malformation. Therefore, implants in such conditions were doomed to failure. Patient selection is the key to successful implantation.

Dental Implantation↗