Comparison of bonding mechanism of a self etching primer and phosphoric acid self etching to enamel by scanning electron microscope-–An in vitro study

An in vitro study was carried out at the Department of Orthodontics and Dentofacial Orthopaedics Tamil Nadu Government Dental College and hospital Chennai with an aim to determine the etching pattern of self etching primer and phosphoric acid etching by scanning electron microscope and correlate it with its shear bond strength. Eighty non-carious premolar teeth that were extracted for orthodontic treatment purposes were used. Two groups of specimens with forty each were prepared to study the etching pattern with self etch primer Transbond plus 3M unitek and 37 orthophosphoric acid 3M ESPE respectively. The bond strength were also determined for both the groups using Transbond XI adhesive 3M unitek and stainless steel metal brackets Gemini series 3M unitek. The results showed that the etch pattern of self etch primer was shallower compared to that of the conventional phosphoric acid etching indicating minimal enamel damage. The shear bond strength of self etch primer 10.27 Mpa was lower compared to that of the conventional phosphoric acid groups 11.85 Mpa which was statistically significant plt.001 best within the acceptable range.