Evaluation of UDMA's potential as a substitute for Bis-GMA in orthodontic adhesives

UoM administered thesis: Master of Philosophy

  • Authors:
  • Alexia Papakonstantinou

Abstract

In response to growing concerns associated with the estrogenic potential of Bis-GMA based dental resins, this study investigates the potential of UDMA based resins to function as substitutes to the currently used Bis-GMA based orthodontic bonding adhesives.Four filled and four unfilled resins with a UDMA to TEGDMA weight ratio 50:50, 60:40, 70:30, 80:20 were formulated, tested and compared to the Bis-GMA control Transbond XT. The properties investigated were: viscosity (rotational viscometry), viscoelasticity, degree of polymerization (FT-IR) and bond strength (shear bond strength test). The viscosity and degree of conversion values were processed using one-way Anova and the post-hoc Tukey HSD test statistic. The shear bond strength values did not follow a normal distribution and were processed using the non-parametric Kruskal-Wallis and Mann-Whitney U-test.In the rheology study, the null hypotheses are that: i) UDMA % will have no affect on viscosity and ii) there is no difference in the viscosity of the filled and unfilled experimental adhesives with the viscosity of Transbond XT and Transbond Primer. There was a significant decrease in the viscosity of the U80:T20(F), U70:T30(F), U60:T40(F) resins, as the TEGDMA concentration was increased. The rest of the experimental adhesives (all unfilled specimens and U50:T50(F)) had comparable viscosities to Transbond Primer. The resins with higher TEGDMA also exhibited lower viscosities, but the difference was not statistically significant.In the polymerization study, the null hypotheses are: i) that UDMA % will have no effect on degree of conversion (DC%) and ii) that there is no difference between the model and commercial adhesives. The findings show that Transbond XT (43.09%) had a significantly lower DC % than all the UDMA based adhesives. Furthermore, there was no significant difference between the means of the various UDMA resins.In the shear bond strength test, the null hypothesis is that there is no significant difference between the mean bond strengths derived for the filled UDMA-based adhesives and Transbond XT. These findings display a comparable bond strength between the U80:T20(F) adhesive and the control Transbond XT. There was no significant difference between the U70:T30 adhesive and the control.The results indicate that adhesives formulated with high UDMA:TEGDMA ratios, can be used to produce resins with greater viscosity and increased bond strength high, potentially without affecting their degree of conversion. Tweaking of the materials formulation can enhance the material characteristic.

Details

Original languageEnglish
Awarding Institution
Supervisors/Advisors
Award date1 Aug 2012