A clinical trial comparing the failure rates of directly bonded brackets using etch times of 15 or 60 seconds

A clinical trial was conducted to compare bond failure when 15-second or 60-second acid etch times were used for the direct bonding of metal edgewise brackets. Bonds totaling 1174 were studied over a period of 6 to 13 months. Analysis of failure rate, bond survival time, and cement remaining after failure showed no statistical difference between the 15-second and 60-second etch groups. There were statistical differences in bond failures relating to the position of the tooth in the arch (p less than 0.001) and to the type of bracket (p less than 0.001).