controller and method name with hypen - secured?

Hi

I use MY_ Router to change the url.
The controller name and methods are defined with _ (ex. this_method)
But i changed them to display like this in the url (http://..../this-method)

I copied a MY_Router from internet and it is working good.
But i don't know whether it is secured. 
Does codeigniter provide any other way to achieve this?

Thanks

Please tell me is it good idea to use router to change the underscore to hyphens?