Determination of residual monomer content in dental acrylic polymers and effect after tissues implantation

Figures & data

Table 1. Applied materials and polymerization methods.

Material	Powder content	Liquid content	Powder /liquid ratio	Polymerization method
Triplex Cold Ivoclar Vivadent, Liechtenstein	PMMA catalyst pigments	Stabilized MMA dimethacrylate catalyst stabilizer	13 g of powder/10 cm^3 of liquid	Cold polymerization at room temperature, without pressure
Triplex Hot Ivoclar Vivadent, Liechtenstein	PMMA catalyst pigments	Stabilized MMA dimethacrylate	23.4 g of powder/10 cm^3 of liquid	Hot polymerization, 100 °C during 45 minutes in special molds

Table 2. Experimental conditions used for MHE-GC-MS analysis.

Agilent 7697A headspace autosampler	Oven equilibration temperature: 180 °C Loop temperature: 185 °C Transfer line temperature: 190 °C Vial equilibration time: 30 min Injection time: 0.03 min
Agilent 7890B gas chromatograph	Injector temperature: 200 °C Column: HP-5MS (5% diphenyl- and 95% dimethylpolysiloxane, 30 m × 0.25 mm, 0.25 µm film thickness; Agilent Technologies, USA) Oven programme: isocratic 40 °C per 4 min; linear gradient 40 °C–60 °C by 5 °C/min; linear gradient 60 °C–260 °C by 40 °C/min; isocratic 260 °C per 2 min MSD transfer line temperature:250 °C Ion source temperature:230 °C Mass analyzer temperature: 150 °C Carrier gas: helium Gas flow:1 cm^3/min Split ratio: 200:1
Analysis time	15 min

Figure 1. Reduction of MMA (treatment 5.4 min) peak area during ten successive extractions.

Figure 2. Evaporation profiles of MMA standard and MMA released from samples of cold polymerized and hot polymerized PMMA.

Figure 3. Contribution of each MMA peak in total MMA peak area for ten successive extractions.

Table 3. Content of MMA in the samples of cold and hot polymerized PMMA.

Polymer	Mass of polymer sample (mg)	Residual monomer content (mg)	Residual monomer content (mgMMA/gPMMA)
Cold-polymerized PMMA	50.91	0.8019	15.75
Hot-polymerized PMMA	50.59	0.5545	10.96

Figure 4. Overlapped peaks (treatment 5.4 min) of MMA and cold and hot polymerized PMMA after the first extraction.

Table 4. Compounds identified in PMMA cold sample after 1st extraction by headspace GC-MS.

Retention time, min	Compound	Peak percentage, %
5.41	Methyl methacrylate	71.30
12.39	Ethylene glycol dimethacrylate	21.40
12.73	Biphenyl	1.17
13.61	Phenyl benzoate	4.99

Figure 5. MMA mass spectrum.

Figure 6. Intense inflammatory reaction and de novo formation of blood vessels one week after implantation of cold polymerized acrylate in m.biceps femoris of male Wistar rats. HE, ×100.

Figure 7. Slight fibrosis two months after implantation of cold polymerized acrylate in m.biceps femoris of male Wistar rats. HE, ×200.

Figure 8. Proliferation of connective-tissue cells and intense fibrosis with a significantly lower intensity of inflammation one week after implantation in m.biceps femoris of male Wistar ratsof hot polymerized acrylic samples. HE, ×100.