![]() Inadequate labial margins and incomplete peripheral roll. Teeth should be centrally seated in tray, which should be seated further into mouth, so teeth are closer to front of tray. Tray not seated correctly placed too far lingually, resulting in lack of marginal detail in labial area and no peripheral roll. Remember to ask patient to lift their tongue. Alginate should be of a smooth consistency with all powder incorporated into mix and no air bubbles. Accurate mixing can be aided by use of alginate mixing machine. Release lip in labial area to ensure alginate flows into this area. No lingual roll.Įnsure adequate spatulation has taken place. Encourage patient to lift tongue so alginate flows into lingual sulcus.Įnsure tray is in ideal position with teeth seated centrally in trough of impression tray before applying even pressure to seat tray.Īir bubbles present all over impression due to inadequate mixing. Seat tray further forward so teeth are more central in trough of impression tray. Impression tray not seated correctly - placed too lingually - denoted by thicker layer of alginate labially. Also ensure upper lip is fully released, allowing alginate to flow fully into sulcus area. Tray possibly under-loaded with alginate. Voids in palate would mean unsuitable if being used to construct a denture. Impression tray visible in the upper right canine region. Overall, this creates a more comfortable experience for the patient, especially if they have a gag reflex. Different manufacturers have different colour-change systems, but the advantage of all systems is that they allow the operator to see exactly how much working time they have and to avoid the impression being seated in the mouth too early. Finally, it will turn back to yellow as it is seated. By the time it has turned peach-coloured, it should be loaded into the tray. For example, Tropicalgin is a yellow powder which will turn red when mixed with water and change to a dark pink as it is mixed. These are designed to indicate to the user how much time should be spent mixing, when to load the tray and finally when to seat the mixture in the mouth. Some alginates have colour-changing properties built in. Setting time is the time it takes for the alginate to set into an elastic mass. Working time is the time it takes to mix the alginate into a smooth, consistent mix, load the tray and seat it in the mouth. The setting time dictates the working time and the actual setting time of the material. These are normal set, fast set and extra-fast set. Setting time very dependent on operator handlingĪlginate can be purchased with a variety of setting times. Incompatibility with some dental stonesģ. Setting time can be controlled with temperature of water usedĢ.
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