The $499 CameraJet toothbrush is absurdly over-engineered. Dyson’s intense new ad makes that the whole point. When I first saw Dyson’s new CameraJet, I thought it looked sorta like a power screwdriver. Then I learned it had a camera. And my immediate reaction was: Why the heck does anyone want a camera on their toothbrush? My wife and I have used Philips Sonicare toothbrushes for about 25 years. They do a phenomenal job, so both of our girls have them too. Toothbrushing is one of those...