Effetto della contaminazione ematica sul distacco di tre differenti tipi di brackets autoleganti: studio sperimentale in vitro

Objectives

To assess the effect of blood contamination on the bonding and bond-failure site of 3 different types of self-ligating bracket.

Materials and methods

Two hundred forty bovine permanent mandibular incisors were randomly divided into 12 groups, each containing 20 specimens. Three different self-ligating brackets (Smart Clip - 3 M Unitek, Monrovia, California, USA; Damon - Ormco, Glendora, California, USA; and Quick - Forestadent, Pforzheim, Germania) were bonded to the teeth with Orthosolo primer (Ormco, Glendora, California, USA) and Trasbond XT composite (3 M Unitek, Monrovia, California, USA). Bonding was tested under different surface enamel conditions: dry, contaminated with blood before priming, contaminated with blood after priming, and contaminated with blood before and after priming. After bonding, all samples were stored in distilled water at room temperature for 24 hours. Shear bond strength was then evaluated with a universal testing machine (Mod. 4301, Instron Corp., Canton, Massachussets, USA). After bond failure, the bracket bases and the enamel surfaces were examined under an optical microscope (Stereomicroscope SR, Zeiss, Oberkochen, Germany) at 10 x magnification, and the amount of adhesive left on the enamel surface was rated with the adhesive remnant index (ARI). All the data were statistically analyzed (Chi-square test; level of significance p < 0.05).

Results and conclusions

ARIs of 2 were more frequent among samples bonded to dry enamel, whereas samples bonded to blood-contaminated enamel (before, after, or before and after priming) exhibited a higher frequency of ARI 0. However, there were no significant differences between the ARI scores for the 3 conditions of contaminated enamel or for those related to the 3 types of self-ligating brackets tested.