**6. Dental impression trays**

**4.3. Preparation of dentures on the basis of poly(methyl methacrylate)**

mixed previously with pigment is subjected to this process [12, 36].

can be easily adjusted according to the user [36].

(bone tissue from which the core of the tooth is built).

**5. Dental adhesives**

reconstruct a tooth [37].

ethylene glycol dimethacrylate [12].

36 Acrylic Polymers in Healthcare

Poly (methyl methacrylate) constitutes a raw material for the preparation of artificial teeth. However, this polymer to be able to be used for this purpose should be characterized by a high molecular weight and a high cross-linking degree. The starting material consists of PMMA or a copolymer of the mentioned polymer with 1,4-butanediol dimethacrylate or with

Crucial meaning for the quality of the denture has a method of polymerization. It is generally carried out at elevated temperature. However, for some substrates that have a tendency towards spontaneous polymerization, process must be carried out at room temperature [12, 36]. Preparation of artificial teeth from the raw material which is PMMA is a multistep process. Initially, 90% of the mixture is represented by monomers, and the remaining 10% constitutes a pigment selected depending on the desired colour of the final product. Depending on the requirements of the final material, it is possible to obtain colourless acrylic mass or mass with the white or pink colours. White acrylic mass is then used to produce dental crowns, inlays or artificial teeth, while the pink one is useful in obtaining products such as impression trays [12, 36]. The next step is subjecting the mixture of trituration process by means of ball mills. Such process depending on the properties of applied reagents takes 24–48 h. Homogeneous mass after trituration process is left in a closed container until reaching the material of gum consistency. Such a mass is then divided into smaller parts which are distributed to the appropriate forms. The moulds are then assembled and subjected to pressing at elevated temperature. At high temperature and under elevated pressure, polymerization process takes place, and final product is obtained. Next, obtained polymer is gradually cooled and formed into its final form by cutting off unpolymerized portions. Subsequently, obtained teeth based on PMMA are affixed to the polymeric plate. An alternative method for the preparation of artificial teeth is a method using the process of injection into the mould at elevated pressure. Molten polymer

Prepared dental prostheses are characterized by a lack of smell, and furthermore, their sizes

The primary function of dental adhesives is affixing to the tooth surface or to the elements included in the oral materials such as dentures or dental bridges used in order to restore or to

As in the case of dental prostheses based on poly(methyl methacrylate), dental adhesives made of this polymer are also characterized by slightly poor mechanical properties. From the user's perspective, the most important is proper adhesion of glue to the enamel or dentin

With inadequate adhesion of the adhesive, which results in insufficient adhesion of the prosthesis, or a dental bridge phenomenon of secondary caries can occur, then treatment is Acrylic materials represent an important component used in the preparation of individual impression trays. As in the case of above-described cement materials, also materials used for the preparation of impression trays consist of liquid and powder. The fluid is a mixture of methyl methacrylate (90% of a liquid), a suitable catalyst and an oil of mineral origin, while powder consists of inorganic fillers such as talc, chalk or aluminium oxide [11].

The first step in order to obtain an impression element is preparation of plates of a certain size from a previously prepared mixture of liquid and powder. It is essential to choose a suitable proportion of the components. Then, the mixture is prepared in a silicone container. The plate is then introduced into a gypsum mould; elements protruding from the model are cut off. Next, plate is wiped to a smooth surface, and then prepared material is subjected to polymerization process [11].
