woman smiling after getting an alginate impression

What Is An Alginate Impression?

Alginate impression material helps dentists take accurate impressions of the teeth for a variety of devices and treatments. This goo that's used to help craft dental bridges, veneers and retainers comes from a surprising source: seaweed. Also known as an irreversible hydrocolloid impression, alginate material is a widely used product in dentistry.

What Is Alginate Made Of?

Alginate is a powder that contains potassium alginate, calcium sulfate and a few other elements derived from brown algae and kelp, according to the Dental Corporation of America. Combined with water, it turns into a gel that sets firmly enough to use as a mold. The material comes in a few different formulas. The setting time varies depending on the temperature and the amount of water used.

Alginate Impression Uses

Dental impressions are used for any device that has to fit over or replace any of your teeth, such as mouth guards, braces, bridges, crowns and veneers. An accurate impression of your teeth will help your dentist make a reproduction in another material that can be used as a model for making these prosthetics and tools.

Making an Alginate Impression

Before they begin work, your dentist or dental hygienist will fit you for an impression tray, usually made from a rigid material, such as metal or stiff plastic. Your teeth will be sprayed clean of any debris or extra saliva and allowed to partially dry, notes Guided Surgery Solutions.

The next step in making a successful alginate impression is mixing the powdered additive and water to make a smooth, spreadable liquid. Your dentist will spoon this gel into the tray and smooth it over your teeth with a tool or gloved fingers, being careful to work quickly, but not create any bubbles or lumps that might result in flaws in the final mold.

The mixture will be firmly held in place and removed after a few minutes when the gel has completely set.

Usually, within 30 minutes of being taken out of your mouth the impression is filled with one of several types of impression stone – a plaster-like liquid that dries to a solid. When the stone is fully hardened, it is pulled away from the soft gel in the tray. Any excess stone is then trimmed in the dental office or lab making the device.

Alginate impression material is biodegradable, so with proper disposal your dentist can make it a part of their green initiative. (The Eco Dentistry Association offers other ways for dental offices to create less waste.) Your teeth might be fitted several times throughout your life, so remember: relax while you await your new dental device and be thankful for the power of seaweed!

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