Is it safe to have braces for the second time?

Many adults have a second round of orthodontic treatment because they stopped wearing their retainers after the first round of treatment, which has led to the subsequent shifting of their teeth.As long as your bone levels and root lengths are good, and you have no active tooth decay, it should be fine to undergo orthodontic treatment for a second time. 

You shouldnt have any problems going through orthodontic treatment a second time.  Usually assuming your bite is fitting properly your retreatment is a very short 6-8 months of braces.  Invisalign is often an excellent choice for retreatment if you prefer not wearing braces.