To be precise - Prozac is a SSRI (affects serotonon) and Effexor XR is a SSNRI (affects Serotonin and norepinephrine). Did one work better than the other? If so, then that is the "family" you should be considering.
Teeth Clinching during sleep is a potential side effect of SNRI's like Effexor and Cymbalta. It is not one of the most common side effects, but some people do experience this.
One thing you can do to ease the impact of this side effect is to get a molded retainer to wear while sleeping. This will reduce the fatuge on your jaw and eliminate damage to your teeth.
Contact your dentist about this and he or she will know exactly what you need.
About the depression always returning upon discontinuation of your meds....... I know my friend and I am right there with you. Unfortunatly if your depressive condition is of a more severe and cronic form then medication is always required to keep it at bay.
There is no cure as of yet, only treatment.
Like you I also hate having to take meds. 16 years and counting now.
In that 16 years I have tried absolutly every alternative treatment known to modern science and medication is the only thing that has produced long term relief from this most devistating condition.
But there is some good news. The fact that you have only been on two different AD medications since 1991 shows that your body is not building a rapid resistance to SSRI's and SNRI's.
9 different drug changes for me since 1992. My body builds up resistance to AD medications after only a couple years so I have to keep changing every few years to get the same effect.
Try that retainer I mentioned.