IADR Abstract Archives
The Plasticizer Effect on the Properties of Provisional Restoration Materials
Objectives: To investigate the effects of a plasticiser (di-butyl phthalate, DBP) on the physicalcomechanical properties of two provisional materials with similar formulations: Trim (TCB, Bosworth) a commercial product with DBP and Isobutyl methacrylate/poly(ethyl methacrylate) (IBMA/PEM) as plasticizer free, experimental material.
Methods: For water absorption/desorption studies rectangular samples (40×10×1mm) of each material were prepared and immersed in deionised water (DW, control) and artificial saliva (AS). %Solubility, diffusion coefficients (D) for uptake/loss processes and the exotherm behaviour were measured. The flexural modulus was measured (three point bending; rectangular samples80×10×4mm), in the dry state and after storage in DW for 9 days. A nonparametric statistical test was used; n=6 in all cases.
Results: TCB showed a higher equilibrium uptake/loss in both DW and AS compared with IBMA/PEM P<0.05 (Table 1). TCB had a lower diffusion coefficient in both DW and AS, during water absorption/ desorption compared with IBMA/PEM (Table 1). The solubility of IBMA/PEM (0.19%) was significantly higher than TCB in AS (0.11%). TCB had a higher polymerisation peak temperature (~10oC) and reached the maximum exotherm faster than IBMA/PEM (P<0.05). The flexural modulus of the dry samples was significantly higher with TCB (1.28GPa) than IBMA/PEM (1.11GPa). However, after immersion in DW (nine days) it decreased dramatically by 35% (P<0.05); IBMA/PEM showed no difference (P>0.05) between the dry and wet samples.
Table 1: Equilibrium uptake/loss and diffusion coefficient data (standard deviations)
Materials | %uptake | %loss | D(m2.sec-1)uptake | D(m2.sec-1)loss | ||||
DW | AS | DW | AS | DW | AS | DW | AS | |
Trim | 2.3(0.069) | 1.5(0.046) | 2.4(0.084) | 1.6(0.043) | 1.096x10-12(0.009) | 4x10-12(0.029) | 9.4x10-12(0.024) | 1x10-11(0.022) |
IBMA/PEM | 0.8(0.056) | 0.66(0.052) | 1.0(0.028) | 0.85(0.026) | 1.1x10-11(0.068) | 1.5x10-11(0.058) | 1.52x10-11(0.049) | 1.5x10-11(0.046) |
Conclusion: DBP negatively affected TCB's properties, by increasing its water uptake and polymerization peak temperature, and decreasing the flexural modulus after nine days immersion in DW. Further studies need to be focused on plasticiser free, provisional materials with acceptable physicomechanical properties.