I just saw this in a journal; Progress in Orthodontics.
For years we have know that poorly shaped pacifiers can give a poor support, and aid poor developments of an infant’s, or young child’s dental arches, and oral structures.
This research article studied how pacifier use can effect the developing oral-facial musculature, and structure. They also examined how pacifier use effect open bite, and posterior cross bite.
They have found the the shape of the pacifier has a large impact on the prevalence of open bite, but the incidence of cross bite, is less well correlated. So, I would encourage parents to use an orthodontic pacifier for their children, for a better oral structural development.
The effect of pacifier sucking on orofacial structures: a systematic literature review
Non-nutritive sucking habits may adversely affect the orofacial complex. This systematic literature review aimed to find scientific evidence on the effect of pacifier sucking on orofacial structures.
High level of evidence of the effect of sucking habits on orofacial structures is missing. The available studies show severe or moderate risk of bias; hence, the findings in the literature need to be very carefully evaluated.
There is moderate evidence that the use of pacifier is associated with anterior open bite and posterior crossbite, thus affecting the harmonious development of orofacial structures.
Functional/orthodontic pacifiers reduce the prevalence of open bite when compared to the conventional ones, but evidence is needed concerning the effects on posterior crossbite. Well-designed randomized controlled trials are needed to further analyze the effects of functional/orthodontic and conventional pacifiers on orofacial structures.