An investigation into the flexural strength of orthodontic resin with the addition of colour concentrate.

Abstract

Objectives: To measure the flexural strength of orthodontic resin with the addition of a colour concentrate and to see whether different amounts of colour will have an effect on the flexural strength. Materials and Methods: Four groups were created with 20 specimens in each. Group A contained clear acrylic. The other three groups contained different amounts of colour concentrate; Group B contained 10%, Group C contained 35% and Group D contained 50%. The dimensions of 64mm long x 10mm +/- 0.03mm wide x 2.5 +/- 0.03mm in depth were used as specified by the British Standard for Orthodontic Resin. A Lloyds testing machine was used with the Nexygen software to carry out a three point bend test. This records the maximum deflection (mm) and the maximum applied load (N) to cause a fracture. From these results, the transverse strength was calculated. A one-way ANOVA test was used to analyse the results and determine any statistical difference with the mean maximum load values. Results: When adding colour to orthodontic resin, Group B required 78.04N to fracture the material, Group C required 82.36N to fracture the material and Group D required an average of 88.56N to fracture the material. The ANOVA test calculated a ‘p’ value of 0.114245 showing no statistical significance between groups. Conclusion: The flexural test resulted in a small increase in strength as the amount of colour concentrate added was increased. A one-way ANOVA test showed no statistical significance.