Children who were bottle-fed or used pacifiers as babies are at risk of dental problems in preschool, a new study suggests.

Specifically, the researchers found that babies who sucked their thumbs or a pacifier after one year of age, or drank out of a bottle in the first three months of life, were significantly more likely to have misaligned baby teeth at 3 to 5 years of age.

These changes likely stem from differences in how the child sucks a bottle or pacifier and how it feeds from the breast, study author Dr. Domenico Viggiano told Reuters Health.

If possible, children "needn't use a pacifier," and if they do, they should try to stop before they turn two years old, advised the researcher, who is based at the Local Health Unit "Salerno 1" in Italy.

He added that some misalignments in baby teeth can cause problems for adult teeth, once they start to come in at age 6.

In the Archives of Disease in Childhood, Viggiano and his colleagues explain that many factors can influence the development of the jaw, dental arches, tongue and facial muscles. Some experts have suggested that one of those factors may be the use of pacifiers or children's preferences for thumb-sucking.

To investigate whether thumb-sucking, using a pacifier or feeding with a bottle can influence dental development, the researchers surveyed the parents of 1130 children between the ages of 3 and 5 about their children's habits during the first months of life. Children also underwent a thorough dental examination.

In general, more than one-third of children showed some type of bite problem. Around 13 percent had an anterior open bite, in which their top and bottom front teeth did not connect when they bit down. Seven percent had a posterior cross-bite, in which their top back teeth bite along the inside of the bottom back teeth. In normal alignment, the bottom back teeth hit the inside of the top back teeth.

Nearly 9 out of 10 children with an open bite had sucked a pacifier or thumb after one year of life

Viggiano and his team also found that children who started bottle feeding before 3 months of age were significantly more likely to develop a posterior cross-bite.

Children who sucked on a pacifier or thumb after one year of age were also more likely to develop a posterior cross-bite. However, those who breastfed exclusively for longer than the first 3 months of life were less likely than bottle-fed children to develop the misalignment, suggesting that breastfeeding can protect kids from dental ills, the authors note.

In general, sucking a thumb or pacifier appeared to affect bite patterns more strongly than feeding from a bottle, the authors note.

Viggiano explained that we grow most of our craniofacial structures in the first 4 years of life. "Excessive thumb or pacifier sucking sets up abnormal forces in the oral cavity - lips, tongue, dental arcades, palate - and affects the development of the muscles of the mouth and face, and the palate," he added.

Bottle feeding may also affect jaw alignment because using a bottle requires more powerful sucking from the lips and cheeks than feeding from a breast, he noted.