**Acrylates and Their Alternatives in Dental Applications**

**Acrylates and Their Alternatives in Dental Applications**

DOI: 10.5772/intechopen.69010

Lavinia Cosmina Ardelean, Cristina Maria Bortun, Angela Codruta Podariu and Laura Cristina Rusu Angela Codruta Podariu and Laura Cristina Rusu Additional information is available at the end of the chapter

Lavinia Cosmina Ardelean, Cristina Maria Bortun,

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/intechopen.69010

#### **Abstract**

Acrylic resins dominated dentures technology for several decades. Due to their many disadvantages, new classes of resins, which promise better quality, constantly appear. Mechanical properties of acrylic resins, including fracture behaviour, water absorption and mechanical strength degradation caused by the exposure to saliva of classical heatcured acrylic resins compared to alternative urethane-based light-cured resins, were carried out. The allergy potential of acrylic resins was evaluated by *in vivo* and *in vitro* tests. New choices of resins, like thermoplastic injected resins, light-cured or milled highperformance polymers, with better properties compared to acrylics, suitable for dental applications are being presented.

**Keywords:** acrylates in dentistry, alternative resins for dental use, thermoplastic resins, light-cured resins

#### **1. Introduction**

In dentistry, non-metallic materials for denture manufacturing have a long tradition [1]. Among the first materials used, wood, ivory and dentin from hippopotamus teeth or even human teeth may be found. These types of dentures were considered a luxury, due to their prohibitive price and only rich people could afford them. Charles Goodyear discovered vulcanized rubber in 1839. This was the premise for manufacturing dentures with rubber base, much more cheaper and accessible to any pocket [2]. Celluloid, which appeared in 1871, was the first artificial polymer competing with rubber. But, this was not able to overcome the drawbacks such as dimensional instability, deformability and problems in processing technology. Resins represented a huge step forward in dentistry and the first heat-cured acrylic was reported in 1936 [3]. First chemical studies regarding

diacrylic composite resins-type urethane polymers were also carried out at that time by Otto Bayer in the IG Farben Laboratories in Leverkusen. Acrylics, in fact poly(methyl methacrylate) (PMMA) mixed with methyl methacrylate, dominated denture technology for several decades. There were no competitors in manufacturing denture bases, artificial teeth, orthodontic appliances, single-tooth or provisional restorations or as veneering materials (**Figure 1**).

The toxicity of the residual monomer, the complex wrapping system, difficult processing and poor resistance are some of the disadvantages of these materials. Many new classes of resins/macromolecular compounds which promise better quality came on to the market such as diacrylic, styrene, polycarbonate, epiminic, polyurethane, vinyl, polyamide, acetal and polyglass. Besides classic heat-curing, alternative technologies namely, casting and injection moulding are nowadays available in manufacturing acrylic resins for dental applications. In the case of alternative resins, light-curing or microwave polymerization techniques are also used [4, 5]. Light-curing, as a polymerization method for dental materials, appeared in the 1970s. Initially, ultraviolet light was used. Afterwards, it was replaced by visible radiation (visible spectrum wavelength/electromagnetic waves), the light source being either a halogen bulb or xenon stroboscopic lamps [6, 7]. The classification of resins according to DIN EN ISO 1567 is presented in **Table 1**.

**Figure 1.** (a) Heat-curing acrylate powder and liquid and (b) mixing the acrylic paste.


**Table 1.** The classification of resins according to DIN EN ISO 1567.
