Testing of residual monomer content reduction possibility on acrilic resins quality

The Use of Acrylate Polymers in Dentistry

The manuscript aimed to review the types of acrylate polymers used in dentistry, as well as their chemical, physical, mechanical, and biological properties. Regarding their consistency and purpose, dental acrylate polymers are divided into hard (brittle), which includes acrylates for the production of plate denture bases, obturator prostheses, epitheses and maxillofacial prostheses, their repairs and lining, and soft (flexible), which are used for lining denture bases in special indications. Concerning the composition and method of polymerization initiation, polymers for the production of denture bases are divided into four types: heat-, cold-, light-, and microwave-polymerized. CAD/CAM acrylate dentures are made from factory blocks of dental acrylates and show optimal mechanical and physical properties, undoubtedly better monomer polymerization and thus biocompatibility, and stability of the shape and colour of the base and dentures. Regardless of the number of advantages that these polymers have to offer, they also exhibit certain disadvantages. Technological development enables the enhancement of all acrylate properties to respond better to the demands of the profession. Special attention should be paid to improving the biological characteristics of acrylate polymers, due to reported adverse reactions of patients and dental staff to potentially toxic substances released during their preparation and use.

Ultrasonic cleaning reduces the residual monomer in acrylic resins

Background/purpose

The residual monomer remaining in acrylic resin can cause an allergic reaction and is toxic to oral soft tissue. This study determined the effect of the duration of ultrasonic cleaning on the amount of residual methyl methacrylate monomer in one heat-polymerized acrylic resin, Meliodent, and three autopolymerized acrylic resins, Unifast Trad Ivory, Unifast Trad Pink, and Unifast III.

Materials and methods

Thirty-six disc-shaped specimens of each brand were prepared and randomly divided into six groups: control (no treatment), positive control, and ultrasonic treatment in 50°C water for 3 minutes, 5 minutes, 10 minutes, or 15 minutes. The residual monomer was extracted and analyzed using high performance liquid chromatography.

Results

There were no significant differences in the residual monomer amount in the Meliodent groups. The amounts of residual monomer in the autopolymerized acrylic resin positive control group and ultrasonic treatment groups were significantly lower than those of the control group for the Unifast Trad Ivory, Unifast Trad Pink, and Unifast III groups (P < 0.05). The amount of residual monomer was not significantly different between the ultrasonic treatment in 50°C water (3 minutes for Unifast Trad Pink and 5 minutes for Unifast Trad Ivory and Unifast III) groups and the positive control group (P > 0.05).

Conclusion

Ultrasonic treatment with 50°C water for 3–5 minutes for autopolymerized resin and 3 minutes for heat-polymerized acrylic resin reduced the amount of residual monomer similarly to previously recommended methods, using shorter treatment times.