After rinse with salt water, do we need to rinse with water again if dental work?

Sort of. You could probably get by with out rinsing with plain water but the salty taste can not be pleasant. The salt water rinse will not harm your teeth.
No. No rinsing with water after rinsing with salt water is not necessary.

Related Questions

Does a a salt water rinse contribute anything of value after dental work?

Yes. Warm salt water rinses are good for easing discomfort in the soft tissues of your mouth; gums and injection site in particular. Read more...
Salt water. Usually you do not need to use salt water after every dental procedure. A salt water rinse is useful after an extraction. Read more...