Dental malocclusion at the navel of the Xingu river

The feeling of coexisting with and treating a highly prevalent disease of which origin is unknown is unsettling. It reminds us of when heavy drugs were used to treat cancer of which association with Genetics was still unknown — in fact, nothing was known about the fact that the origin of cancer was right there, in the nucleus of the cell, in the DNA. And this logically resulted in a waste of time and lives. However, when the time came for oncologists and geneticists — cloistered in their laboratories, traveling into the nucleus of the cell — to meet, science made a gold-medal jump and Oncogenetics, the new science, sat on the front chairs of Oncology conferences. Although millions of people undergo orthodontic treatment, the causes of malocclusion have not yet been clearly determined. That certainly is a paradox for a contemporary world that strives to offer evidence of facts. What is even worse is to know that discussions on malocclusion, held in orthodontic events, raise significantly less interest than presentations about new material and new treatment techniques. Would we be walking towards the same abyss Medicine, a science that does not admit delays, has fallen into? It all began with Begg2 who, in 1954, studied the skulls of Australian aborigines. He established that malocclusion is “a disease of modern civilization” caused by tooth wear. Understanding Begg’s findings means perceiving the brilliant history that influenced the origins of Orthodontics and provided the road that enabled extraction of permanent teeth for space opening in the dental arch so as to counterbalance the absence of interproximal wear. Nevertheless, Begg’s concepts went beyond technicality, which bothers a lot of people, as Omar Gabriel would say. A macro analysis reveals the remarkable influence of his theory over the hypothesis that malocclusion, especially dental crowding, is mainly of environmental etiology. Begg’s theory is still controversial and has been discussed under four models of investigation: 1) experiments with animal models; 2) analysis of ancestors’ skulls gleaned by means of excavations, and epidemiological studies conducted with primitive/ isolated populations; 4) studies conducted with human twins. Overall, the findings have given support to the hypothesis that malocclusion is basically of environmental etiology. Nevertheless, the issue is not as simple as it may seem and, for this reason, must be brought to light. One should assume that a given malocclusion probably has different etiological factors in comparison to other occlusal alterations. The fact that the obvious may be concealed intrigues a whole generation of uneasy orthodontists who believe that if we repeat the same mistakes made by Oncology — restrain the micro look taken at the nucleus of the cell and the DNA — we may pay a high price for a torpid progress. Following Begg’s line of reasoning, I decided to provoke the monolith of orthodontic architecture by trying to reproduce his finding under a micro look: the DNA. I chose to study the indigenous people from the Brazilian Amazon3,4 following the pattern established by Begg. I sailed down the profuse Xingu river, carrying Genetics in my saddlebag. Initially, it is worth noting that it is common for the Amerindian (American indigenous) to establish new settlements, whether by means of fission (division) or fusion (union). Thus, it is easy to understand that miscegenation contributes to increasing genetic variation among indigenous people, which counterbalances with low intratribal variation.5 Therefore, unlike what it is commonly believed, indigenous groups are genetically different from each other, even though the individuals comprising the same village are similar in appearance. Would that be the perfect opportunity for me to answer my questions regarding the theme? I put on my indigenist boots and my researcher saddlebag and, just like Begg who is now disguised in the brazilianity of a Villas-Bôas, I steered my horse towards the Xingu river where I remained between 2009 and 2010. The area has several settlements consisted of indigenous people of nine different ethnic groups. It is, therefore, one of the most ethnically diverse human community in the world. During our first trip, we established contact with two Arara villages. Thus, two genetically different settlements. An anthropological study about the Arara people6 revealed that the individuals comprising the Arara of Iriri village come from the same family who descend from a couple who,