Dental Grade Sodium Alginate

 

 

Dental-grade alginate is a natural polysaccharide polymer extracted from marine brown algae. It can react with calcium salts to form a thermally irreversible gel. Among them, the commonly used alginate is sodium alginate and potassium alginate. They are widely used in dental impression materials.

 

Alginic acid dental impression materials are irreversible hydrogel impression materials. Their core principle is to utilize the "solvation-gelation transformation" of sodium alginate and calcium ions, which causes it to rapidly change from a fluid paste (solute) to a resilient solid (gel) in the oral cavity, thereby precisely replicating the shape of teeth and their surrounding tissues.

 

The composition of the dentin bonding material (typically a two-component paste)

To precisely control the gel time and optimize performance, commercial alginate impression materials are usually supplied in the form of two tubes of paste.

 

 

Alginic acid sodium: Provides the basis for the gel.

Fillers: Such as silica and diatomite, are used to increase viscosity, adjust strength and reduce shrinkage.

Plasticizers: For example, glycerol, can enhance the elasticity and flexibility of the gel, preventing it from becoming overly brittle.

Retarders/Regulators: For example, phosphate (such as trisodium phosphate). Its function is to preferentially combine with calcium ions, delay the reaction process, and thereby provide sufficient operating time for the operation.

 

 

Calcium salts: The most common one is calcium sulfate (gypsum powder), which can provide the calcium ions needed for forming the cross-linked structure.

Fillers: Also used to adjust the viscosity and texture of the paste.

Auxiliary catalysts: For example, alkali metal carbonates, which can regulate the reaction rate.

Colorants and flavorings: Enhance the appearance and taste of the product.

 

 

When the two components are mixed in the mixing bowl according to the specified ratio, the following key reactions occur:

1) Initial stage (solid state): After the mixture is completed, the paste has some viscosity but is still flowable. At this time, the retarder (phosphate) will preferentially combine with some calcium ions released from the catalyst paste to form a soluble complex, temporarily preventing the calcium ions from reacting with the alginate sodium. This provides the clinician with an operation time (usually 45 seconds to 1.5 minutes) to load the material onto the tray and place it in the mouth.

2) Gelation stage: Once the retarder is exhausted, the free calcium ions will combine with the glucuronic acid units on the alginate sodium molecule chains to form a three-dimensional ionic cross-linked "egg box" structure network. At this point, the material will rapidly transform from a solution state to an elastic gel state.

3) After the reaction is completed, a stable and elastic model will be formed, which can precisely record details.

 

Item	Index
Appearance	Cream colored or lighter
Mesh	200 Mesh
Moisture, %	≦15.0
Ash, %	18-27
Viscosity, mPa·s	According to the need
Strength, g/c㎡	According to the need