This article indicates that iodine is as effective (at 10% PVP-I, which is 1% available iodine) as any other mouthwash substance. The BIG advantage: iodine is natural. Your body NEEDS it. Your salivary glands REQUIRE it. This is not true of chlorhexidane (an invented antiseptic) nor sodium hypochlorite (household bleach).
You walk into the dentist’s office. In due course, you climb into the chair, get a napkin clipped around your neck, and someone looks deep into your mouth. They poke around a little, but it doesn’t really hurt. Maybe it’s a nurse, a dental assistant. She takes a step back, looks at you, and says, “Hey, you are doing really great! I don’t see any new cavities; there’s very little tartar or calculus build-up. Your gums are healthy, no bleeding. What have you been doing different?”