I use a Therapeutica Pillow. It's FABULOUS!!!
It's not like most cervical pillows that basically just have a "roll" at your neck. It has three sections. In the middle is a head shaped dent (half sphere) with a roll for your neck, plus a ramp down your neck to your shoulders. Does that make sense? The ramp is about the width of a normal person's neck. Normal cervical pillows don't have this, and the lower part of your neck (very upper back) isn't supported without it. Anyway, this part of the pillow is obviously for sleeping on your back. I've used it because I had to get out of the side sleeping habit and needed a pillow that fully supported me on my back.
On either side of the middle back sleeping part are the side sleeping parts (one for each side). These areas are much like normal cervical pillows, except they have a hollowed out area where your jaw bone is so as to limit the lateral pressure on your jaw, which is really the worst thing about sleeping on your side. I have TMJ disorder and sleeping on my side on my Therapeutica Pillow was better than doing so on a normal pillow, but I still found that sleeping on my back was best. It's a hard habit to get into but back sleeping is the healthiest sleeping position, for everyone.
The thing about this pillow is that if you don't have good everyday posture, it takes a lot of getting used to. The first 2 to 3 weeks were awful, very restless. Once your posture improves though, it's awesome. I love that pillow now and can't sleep without it. I take it on business trips to use in my hotel because normal hotel pillows just don't cut it anymore.
Also, it makes it easier to get used to if you use other pillows under your knees when on your back, or between your knees when on your side.
Melanie