Which primary teeth are least affected by nursing bottle syndrome?

Nursing bottle syndrome, also known as early childhood caries or bottle mouth syndrome, is primarily associated with prolonged exposure of a child's teeth to sugary liquids, particularly when a child falls asleep with a bottle. The teeth that are most frequently affected are typically those that are more exposed to the sugary liquids due to their location in the mouth and their susceptibility to decay.

Mandibular incisors are located in the front of the mouth and are less susceptible to the conditions that cause nursing bottle syndrome. These teeth are typically less prone to decay because they are less involved in the mastication process when the child is consuming beverages from a bottle and are less likely to be bathed in sugary liquids compared to molars and maxillary incisors, which are more posterior and are subjected to more exposure during feeding.

In contrast, maxillary molars and incisors, as well as maxillary and mandibular canines, are positioned in such a way that they often interact with the sugary substrates poured into a bottle. This, combined with their developmental patterns and the increased risk of retaining fluids around them, makes them more susceptible to decay due to nursing bottle syndrome.

Thus, mandibular incisors are least affected by nursing bottle syndrome, making them the correct answer.