My cousin, who practices out in CA, recommended we do not use electronic toothbrushes. He said that too many people use it incorrectly and end up pushing their gums back. I had been using an Oral-b for 10+ years and went back to very soft bristle regular toothbrush and waterpik.
Added: I was also told by several dentists that for women, cavities often occur with hormonal changes. I've only ever had cavities once in my life, right after having my first child!