These scanning softwares can be used to analyze and compare non-regular geometric shapes as those of teeth to check for dimensional stability in alginate material over a period.ĭefects (nodules or blebs) on the occlusal surface of the casts are commonly observed on the occlusal surface of the stone casts fabricated from alginate impressions. In recent times, CAD/CAM is used for digitization of the alginate impression material for precise impression taking to improve the outcome of the final prosthesis ( Jin et al., 2018, Kim et al., 2015). Advanced alginates include, infection free, color changing, high viscosity alginates ( Hiroshima, 2003, Taylor et al., 2002, Soares and Ueti, 2001). Furthermore, to prevent alginate dust, de-dusting agents and minerals have been incorporated to inhibit toxic silica inhalation. Therefore, efforts to improve alginate impressions has received scientific attention and such attempts include extended pour alginates, to increase the pouring time up to 1–4 weeks ( Jamani, 2002, Walker et al., 2010). Alginate dust in the form of components like silica, lead and cadmium are also present in its powder, which has toxic potential ( Anusavice, 2003). In addition, it has poor tear resistance, resulting in tearing when used in deep undercut areas or recording sub-gingival contours ( Craig, 2002). Alginate impressions are used to form dental gypsum and stone, study and definitive casts for the purpose of diagnosis and evaluation, record keeping, provisional and final restorations, mouth guards and bleaching trays ( Nandini et al., 2008, Sedda et al., 2008).Īlthough alginate is universally employed for various applications, it appears to have poor dimensional stability due to imbibition and desiccation and must be poured within 10–12 min to avoid distortion ( Donovan and Chee, 2004, Combe and Douglas, 1999, Fellows and Thomas, 2009). It is extensively used due to low technique sensitivity, hydrophilicity, pleasant taste and odor, ease of manipulation, low cost, long shelf life and compatibility with cast material ( Carr and Brown, 2008). Alginate consists of a chemical reaction which includes mixing of sodium alginate and calcium sulphate with water forming a calcium alginate gel ( Carr and Brown, 2008). Alginate impression material is an elastic irreversible hydrocolloid most commonly used in dental applications ( Ashley et al., 2005).
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