![]() ![]() The extracted alginic acid is then converted into a salt (alginate) of sodium, calcium, potassium or magnesium. Alginates are salts of alginic acid, a polysaccharide extracted from the cell walls of brown algae (washed, ground and chemically treated, especially the pulp) belonging to the Phaeophyceae family, widespread especially in America. Without a filler, the gel would lack stability and would have a slimy surface covered with synerate exudate. Hydrocolloid materials for dental impressions are available in the form of viscous liquids in the “sol” state or in the form of semi-solid substances of a gelatinous consistency. Reviewers in the Office of Device Evaluation will accept data developed according to ISO-10993, Part 1, with the matrix as modified and presented in Blue Book Memorandum #G95-1 entitled “Use of International Standard ISO-10993, Biological Evaluation of Medical Devices Part-1: Evaluation and Testing.”. In order to harmonize biological response testing with the requirements of other countries, the FDA has recognized the ISO standard. The matrix consists of two tables the Initial Evaluation Tests for Consideration and the Supplementary Evaluation Tests for Consideration. It also uses a tabular format (matrix) for laying out the test requirements based on the various factors discussed above. Accordingly, the International Standard for Organization ISO standard, ISO-10993, Part 1, uses an approach to test selections, which is very similar to the Tripartite Guidance used in the past by the FDA. See 21 Code Federal Regulation CFR Part 872.3660. The device is intended to provide models for studies and for production of restorative prosthetic devices, such as gold inlays and dentures. The Food and Drug Administration (FDA) issued a document in 1998, defining a Dental Impression Material as a class II device composed of materials such as alginate or polysulfide intended to be placed on a preformed impression tray and used to reproduce the structure of a patient’s teeth and gums. Therefore, it is important to understand the material and follow certain fundamental guidelines in order to achieve flawless, predictable impressions and hence avoid repeat impression/restorations. For many years, alginate impression material has been a staple of most dental practice and impression materials are an important consideration for dental clinics even today. Alginate is one of the most frequently used dental materials the alginate impression is usually performed at the first dental visit and its results are fundamental to forming a first “idea” about the patient’s oral health status. Irreversible hydrocolloid impressions are a common part of daily practice. However, this type of impression material, alginates (derived from marine algae), have the advantage of being among the most used in the dental medical field. Conventional impression materials are different, and especially with the advent of digital technology, they have been suffering from a decline in research attention over the last few years. Much progress has been made in the search for new marine derived materials. ![]() All the relevant studies were included in the search with respect to the characteristics and evolution of new marine derived materials. Authors conducted a search of articles in written in English published from 2008 to 2018. A comprehensive review of the current literature was conducted according to the PRISMA guidelines by accessing the NCBI PubMed database. The advantages of using alginate include the low cost, a better tolerability on the part of the patient, the ease of manipulation, the short time needed for execution, the instrumentation and the very simple execution technique and possibility of detecting a detailed impression (even in the presence of undercuts) in a single step. With the removal of the impression, being particularly rich in water, the imprints can deform but later adapt to the original shape due to the elastic properties they possess. They reproduce an imprint faithfully, providing details of a high definition despite the presence of undercuts. Elastic impression materials include reversible (agar-agar), irreversible (alginate) hydrocolloids and synthetic elastomers (polysulfides, polyethers, silicones). ![]() ![]() Hydrocolloids were the first elastic materials to be used in the dental field. ![]()
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