Occlusal and facial features in Amazon indigenous: An insight into the role of genetics and environment in the etiology dental malocclusion.

BACKGROUND: Indigenous people of the Xingu river present a similar tooth wear pattern, practise exclusive breast-feeding, no pacifier use, and have a large intertribal genetic distance.

OBJECTIVE: To revisit the etiology of dental malocclusion features considering these population characteristics.

DESIGN: Occlusion and facial features of five semi-isolated Amazon indigenous populations (n=351) were evaluated and compared to previously published data from urban Amazon people.

RESULTS: Malocclusion prevalence ranged from 33.8% to 66.7%. Overall this prevalence is lower when compared to urban people mainly regarding posterior crossbite. A high intertribal diversity was found. The Arara-Laranjal village had a population with a normal face profile (98%) and a high rate of normal occlusion (66.2%), while another group from the same ethnicity presented a high prevalence of malocclusion, the highest occurrence of Class III malocclusion (32.6%) and long face (34.8%). In Pat-Krô village the population had the highest prevalence of Class II malocclusion (43.9%), convex profile (38.6%), increased overjet (36.8%) and deep bite (15.8%). Another village's population, from the same ethnicity, had a high frequency of anterior open bite (22.6%) and anterior crossbite (12.9%). The highest occurrence of bi-protrusion was found in the group with the lowest prevalence of dental crowding, and vice versa.

CONCLUSIONS: Supported by previous genetic studies and given their similar environmental conditions, the high intertribal diversity of occlusal and facial features suggests that genetic factors contribute substantially to the morphology of occlusal and facial features in the indigenous groups studied. The low prevalence of posterior crossbite in the remote indigenous populations compared with urban populations may relate to prolonged breastfeeding and an absence of pacifiers in the indigenous groups.