Recent studies demonstrate transmission of oral bacteria between spouses and from mother to child. Streptococcus mutans, the main bacteria causing dental decay, has been shown to be transmissible between two people.
Oral bacteria is present in everyone's mouth. It's more abundant with active tooth decay present. The studies show bacteria can be transmitted by kissing, direct contact, from one person to another. It also may be transmitted by indirect contact through utensils, toys, pacifiers, etc.
As a dental office in salt lake city, we do not advocate the limiting of contact between mother and child or between spouses. Prevention and good oral health is the key. We recommend 6 month cleanings and eliminating of cavities when they are small. This way you are limiting the number of active bacteria in your mouth that are able to be transmitted. Also with a clean mouth, the normal bacteria in one's own mouth have no food or sugar to consume. If they are not consuming food, they are not secreting acid on your teeth which cause tooth decay.