I've never found a private dental plan that worked out financially. With most, you will lose money fast (when I looked before, break even was somewhere around $5000 in yearly dental work and you were paying 50%, they were paying 50% so most years you would be way under break even).
As much as the Liberals vastly overpromised and underdelivered with their "free dental care" that is not free by any stretch of the imagination, it does seem to be helpful dental insurance for older canadians.