Hi Mary,
Yes, muscle relaxants can help but you may have to try a few before finding THE one that works for you. You might ask your dr or dentist if you could try Valium at night for about 2 weeks and see if that relieves your symptoms. If it does help, see if you can find a muscle relaxant that also helps. You shouldn't take Valium for a long period of time. Also, see my info below about anti-depressants.
Getting good REM sleep is important for bruxers. You might want to be tested for sleep apnea.
Add Magnesium to your daily diet. It's supposed to help relieve bruxing problems. Also, are you taking a SSRI anti-depressant (Prozac, Zoloft, Lexapro)? These can cause clenching. If you are, ask your doc to add a very small dose of Buspar to the SSRI anti-d or change to a different classification of anti-d's.
Whether or not to get another splint - that's a hard one to answer. What kind is it going to be - lower or upper flat-planed, lower or upper repositioning, or in between? Are all the adjustments fees covered in the initial charge? Note here: bite splints almost always have to be adjusted, often times quite frequently. If there is ever any type of pain or discomfort, seeing the dentist (for free) for a bite splint adjustment is the first step to take. What kind of "promises" or guarantees is this guy making? Does he take time for you and explain everything or is he always in a hurry? What else can he (the dentist) do to help relieve a TMJ flare-up? For example - my dentists allows me to use his ultra-sound machine free of charge (I just have to call first); hot moist towels around the neck too and other things for no extra fee.
These are just a few questions you need to ask yourself and your dentist before making your decision. I do support the use of bite splints, but it is essential for find the right kind for you AND finding a really good bite splint MAKER and adjuster can be quite frustrating. Ask questions.
God bless...
Carol