  Suppose $K$ is a knot in a 3-manifold $Y$, and that $Y$ admits a pair of
distinct contact structures. Assume that $K$ has Legendrian representatives in
each of these contact structures, such that the corresponding
Thurston-Bennequin framings are equivalent. This paper provides a method to
prove that the contact structures resulting from Legendrian surgery along these
two representatives remain distinct. Applying this method to the situation
where the starting manifold is $-\Sigma(2,3,6m+1)$ and the knot is a singular
fiber, together with convex surface theory we can classify the tight contact
structures on certain families of Seifert fiber spaces.
