With bruxism and a night splint: incisors are down to dentin and one is intermittently sensitive, even to water, about 3 days/month. need rapid work?

Depends: Pain is a warning sign. Your worn incisors are causing pain. So it depends on how much pain makes you heed the warning. You can be proactive and see a dentist and discuss ways to both fix your worn teeth and protect them from further wear. Or you can ignore the warning and wait until it gets worse, which it will, and possibly have more serious issues.

See Prosthodontist: You need to see a prosthodontist. They are specialists in this type of treatment. You may need a minimal amount of selected treatment, or a major amount of complex treatment to correct these things. Especially at your age -- this needs to be done correctly and comprehensively by the experts. Good luck to you.

See a TMJ/Sleep Dr.: You need to see a dentist trained in TMJ and sleep to find out what is causing you to brux. Sleep physicians have labeled bruxism as a sleep related movement disorder. Bruxism also can be initiated as a neural reflex response to pain/inflammation signals going to your brain from any body part affected. Anxiety and stress issues also contribute to bruxing. There are many ways to help sensitivity.