Rinsing with salt water will not strengthen your gums directly. It will, however, act somewhat like an antimicrobial. This will help, kill/flushout bacteria that cause perio issues and in turn help your gums become more healthy.
Other some dentistis reccoment mouthwash or dilute H2O2. They all are are good mouth rinses.
Burbon might work too.... If I recall... EtOH needs to be 70% (140 proof) or higher to kill bacteria... Try grain alcohol, or moonshine... when you are done rinsing, you can take the shot
-C