The Aim: evaluation of changes of enamel topographic, structural and enamel minerals mass percentage (calcium and phosphorus) due to absence of orthodontic primer.
Materials and Methods: 20 orthodontic patients were enrolled in this study. All patients as a part of orthodontic treatment planned to extract first premolars. After ethical approval was granted by Research Ethics Committee of faculty of dentistry, Tanta University and written consent from each patient to participate in this study was obtained. The patients divided randomly into, Group (I): 10 patient's first premolar brackets bonded with light cured orthodontic composite without primer. Group (II): 10 patient's first premolar brackets bonded with light cured orthodontic composite with primer. Control group: for both groups bonding only first premolar in one side leaving the opposite side unbounded as a control. After 3 months according to the treatment plane the first premolar tooth extracted, brackets carefully removed, teeth sectioned buccolingually, enamel surface topography was scanned with scanning electron microscopy, calcium and phosphorus mass % was measured using scanning electron microscopy –energy dispersive X ray analytical system (SEM-EDX). The obtained data were histologically and statistically analyzed.
Results: despite the non-significant statistical difference between group (I) and group (II), or between either groups and control group more enamel defects and lower average calcium and phosphorus mass % in group (I) than in group (II) due to absence of orthodontic primer in the form of enamel erosion, cracks and gaps between enamel rods and enamel surface.
Conclusions: orthodontic bonding using composite without primer can resulted in more enamel defects and non-significant decrease in the mean calcium and phosphorous mass percentage.