Effects of adhesive systems in different temperatures on shear bond strength of orthodontic brackets

The temperature might affect the physical and mechanical properties of the adhesive material by reducing the polymerization. The present study aimed to evaluate the effect of temperature on the shear bond strength of metallic orthodontic brackets in various adhesive resin systems. Extracted human premolar teeth were randomly allocated to 8 groups (n=10) for bonding with the two available orthodontics adhesive systems (Transbond XT and NeoBond) at different temperatures: refrigeration temperature (4 °C), room temperature (20 °C), human body temperature (36 °C), and high temperature (50 °C). The shear bond strength (SBS) test was performed using a universal testing machine at a crosshead speed of 0.5 mm/min. The Adhesive Remnant Index (ARI) was assigned to the fractured orthodontic brackets. Data were analyzed using one-way ANOVA, the Tukey’s post-hoc test, and independent t-tests. Transbond XT had higher SBS values than Neobond at all the tested temperatures; however, a statistically significant difference was not observed (P>0.05). The SBS results were minimal at 4 °C and maximal at 36 °C in both the adhesive groups (P<0.05). Heating of orthodontic adhesives to body temperature prior to bonding the brackets in the orthodontic treatment increases the bonding strength of the orthodontic brackets.