(PARCIAL) PUBLICADO NA REVISTA "ORTODONCIA", DA SOCIEDADE ARGENTINA DE ORTODONTIA - ( Primeira Parte) Número71, Mayo, 1972. (Segunda Parte) Número 72, 1972.


    Occlusion, Attrition, Periodonto y otras Características Dentales en Aborígenes Brasileños
    Occlasion, Abrasion, Períodonte et autres Caractéristiques Dentaires chez des Arborigènes Brésiliens
    Okklusio, Abrasion, Parodontium und andere Zahnkarakteristika bei Brasilianischen Eingeborenen



    With the intention of classifying the dentition of contemporary man, who has similar feeding and hygienic habits as those of the primitive man, the teeth of the Yanomamis indians were examined. The Yanomamis were chosen for being racially pure, not having been subjected to any cultural adaptation and for showing the some morphological evolution as the men of our civilization. The present results will later be compared with the researches l made among other American indians, for which we have used the same criterion.

    Racially pure:

    Vallois defines race as "natural groups of men which share inherited physical characteristics regardless of their languages, habits or nationalities". Adopting Denniker's classification," we find twenty seven races which can be divided into four racial groups: white, black, yellow and prirnitiv. On the other hand, because of their differenciations, the races are divided into sub-races and these into families. Although the Yanomamis do not for a race by themselves they are a racially pure group if we consider the lexical and structural evidence; they form a Family probably originated from the Karib or Proto-Karib group although Groenberg and Voegelin classified them as originated from the Macro-Chibcha phylum. They belong to the south-Atlantic sub-race, to the American indian race and to the yellow racial group.

    Small cultural adaptation:

    The Yanomamis speak only one language, live in their authentic environment and have the habits and customs characteristic of their culture. The few changes introduced by the Religious Missions and the National Foundation of the Indian, their only contact with civilization, hove not altered their way of fife. In fact, the work of these two organizations is psychologically remarkable, always respecting the culture of the lndian. According to Ribeiro's External Contacts category the Yanomamis are classified as insolated.

    Morphological evolution:

    Belonging as they do to the yellow racial group the Yanomamis are in a similar stage of morphological evolution as the men of our civilization. The some does not apply to the australian aborigines examined by Begg 11 and Beyron which belong to the primitiv racial group and have a more backward rnorphological evolution than other racial groups.

    Racial characteristics of the Yanomamis:

    They are short, well built and muscular. Their shoulders are slightly wider than their hips. Their trunk is even without narrowing at the waist even among women. Their skin is of a brownish-yellow tint. Their hair is black, thick and lank with round cross-section. Almost non existant beard. Scant hair on their bodies. A mongolion stain frequently appears before the age of three. Dolicocephalous are rare, mesocephalous and brachycephals are predominant. Their face shows typical mongolian characteristics although attenuated. Platyrrhinian. Thick lips. Prominent cheek bones. Almond shaped eyes, narrow and slanted eyelid openings with external cleft higher than the internal one, mongolian plica only among some children. The gonion is in most cases constant. The jaw bane shows a good basal relation. The dental bi-protusion is frequent. The Yanomamis are strong and practically immune to the ailments of the area and due to their isolation have not been contaminated by our diseases. Undoubtedly this health is due to natural selection, the free life and eugenics they practice eliminating at childbirth the offspring with show congenital deformities. They are intelligent, active, gay, kind and proud of their race. They are so free that their chief has no commanding position being merely a leader. They are not aggressive as long as their "ethical code" is respected. Their self confidence is evidence of courage which is proved by their bravery at war and their fearlessness when facing big game.

    Young Yanomomi's female indians with their first born babies. Their, mongolic racial morphological characteristics are evident.


    It is calculated that the Yanomamis nowadays number approximately 6.000 of which 4.000 in Brazil and 2.000 in Venezuela. These are variable estimates since some groups have no contact at all with civilization. In Venezuela they are located at the source of the Orinoco river; in Brazil they live between Uraricuera river (north) and the high Demini river (south), the head of the Manaviche river (west) and the high Mujacai river (east). They have inhabited that area for at least 500 years. Comparing with observations mode last century 1213 we observe a slight northward motion, expanding itself. The Yanomamis examined live near the Religious Missions of Tototobi*, Sucurucu** and Catrimani***. These Missions have a landing field for smail planes, their only link with civilization. They stand near the river's sources but their navigability is possible only when the water is high and even so very difficult as obstacles and rapids are frequent. To reach our objectives we traveled more than I.200 kms. in a one engine airplane above the jungle, starting from Boa Vista, the Capital of Roraima. To reach the wholly authentic indian groups we still had to paddle our way many hours in a canoe and also walk.
    o New Tribes Mission. High Totobi river (affluent of the Demini river), north of the Amazon state near the border with Venezuelan. 

    o Evangelical Mission of the Amazon (Surucucu mountains, source of the Parima river). Federal Territory of Roraima. Near the Venezuelan border. 

    o Catholic mission of "Consolata". Middle of the Catrimani river, Cujubim falls. Federal Territory of Roraima.

    Game and fish:

    The area is rich in game and fish with the exception of the Surucucu mountains. The Yanomamis use bow and arrows to hunt. For medium sized animals they use arrows poisoned with "curare". They do not set traps. They imitate very well the sounds of the animals and the songs of birds which makes hunting easier. Fishing is secondary (with cultural adaptation it tends to increase; we gave them great quantities of fishing hooks, nylon fishing fine, etc.). In summer, the drought season, they poison the waters of ponds and the narrow riverbank between two islands with "timbo" (a woody vine whose bark contains a poison to kill fish). They catch fish with their hand in the holes and burrows, a woman's task. The men catch fish in the river rapids with arrows and must be quick to take their prey before they are eaten by the Caribe ("piranha" fish).

    Cutting tools:

    The Yanomamis have diverse cutting tools of their own culture: stone axes, animal's jawbones, jawbone's teeth, splinters of hard wood, etc. Nevertheless they use their hands and teeth to eat and deal out food.


    Among other things they make pottery vessels of different sizes and shapes. They spin cotton to make sleeping nets and ropes. They weave fibres to make baskets, etc. They make bowls, bows and arrows, etc., out of wood.


    In the Yanomami economy, agriculture is an important complement of the wild harvests. They plant sweet cassava, manioc, bananas, tobacco, cotton, sugar cane (cultural adaptation), medicinal and hallucinogenic herbs. Deforestation is made with stone axes*. They cut the cortex of the big trees wait until they dry and burn them. This task is performed by the whole community. The land thus won is divided into parcels each adult man receiving a share. Once in individual hands the earth is turned over with a stick of hard wood shaped as a hook. Planting and harvesting is a privilege of the land's "owner". A man can only marry after having his own plantation.

    * The indians living near the Missions already have steel axes.

    Animal raising:

    Some Yanomamis have tame animals but they do not raise them with the purpose of eating them or making use of their offspring.

    The Yanomamis cut their food with their hands and their teeth. Roots and fruits are pealed with their teeth.

    Feeding habits:

    1 - Main daily food: Products of the wild harvest and plantation.
    The whole year: bananas (there are nine varieties).
    Periodically: the fruit of a spiny palm tree Guilielmo speciosa, cabbage palm, cacao, other fruits from the woods, honey, and turtle's eggs.
    2. Main food but occasional: game.
    Mammals: several species of monkeys (cuata or spider - monkey, cairara, guariba ar howling - monkey, cuxu), paca, coati, agouti, tapir, deer copybara, wild boar.
    Fowl: Curassow, piping guan, jacu, trumpeter, tinamou, macaw, parrot, toucan.
    Reptiles: Alligator and some varieties of snakes.
    Chelonians: Land-turtle, water-turtle and tortoises.
    lnvertebrata: Larvas from certain species of wasps and bees. Other palm tree larvae.
    3. Secondary complemental: Fishing products. All kinds of fish.
    Food preparation

    The Yanomamis know three ways of cooking:

    1. Grilling: Using a grate of small green sticks placed some 80 cm above the fire, the big game is grilled (in pieces) and the monkey (in one piece). lt. corresponds to our smoked meat. This grilled meat can be preserved for a long time. The moat prepared the Dag, requires a strong masticatory effort.

    2. Boiling: Small game, fowl, fish and paps are boiled in clay pans tapioca coke is boiled on a clay dish (it is made of sweet cassava or grated manioc), ("Beijú"), or is prepared as flour ("macaxeira"). The "macaxeira", very common food, presents thick grains and constitutes a very strong attritive for teeth.

    3, Roasting: Mainly during their trips the indians eat meat directly roosted over the fire. The meat quickly brown on the outside but is very good on the inside (especially if one is hungry).

    * FOTO * Dr. Astor, examinating an old Yanomami. Notice in this man the morphological characteristic of a primitive. Prominent, cheek-bones, thick lips, platyrrhinan. In this respect we must point out that this one is not a typical Yanomami but an atavism, also possible to be found in our civilization. The typical Yanomami belongs to the some stage of morphological evolution than the actual civilized men.

    Oral habtis:

    Lip perforation Men perforate their underlip in the middle. Women make two perforations in their underlip, one in the middle and one at each side near the commissures. Wooden rods of 10 to 15 cms. long are introduced through the perforations piercing the lip. This, has no effect on the teeth.

    Hygienics: The Yanomamis know no hygienic mouth habit, not even mouth-washing.

    "Brejeira": Between one lip -generally the lower one- and the incisors, they use, specially men, a roll made of tabacco leafs, which should produce their lingual movement.

    Other habits:

    They have no oral habits, such as the use of nipples, thumbsucking, etc., since they are nursed up to the age of 3 years.

    S A M P L I N G

    150 Yanomamis older than 12 years of age were examined.

    Age Criterion:
    Adolescents 13-18 years old
    Adults 9-29 years old
    Mature 30-49 years old
    Senile 50 or more years old

    We took as a principle to record 13 years when the second molar teeth were near or in recent occlusion. The comparative occlusive wear between the firs and second molar tooth provided information to appraise how long ago the second molar tooth started its activity. For the following ages even an approximate appraisal was not easy to determine. The numerical evaluation of the Yanomamis consists of one, two and many ... They know however the age related to other relatives, which allowed us a chain of deductions. Puberty among girls is well characterized and is announced in a ritual for it enables her to marry. This happens immediately because generally they are already engaged before hand. Considering that in this tropical area puberty among girls must take place around the age of twelve, we assume they are fourteen when the first child is born. According to the chronological dental eruption in the child we could estimate the mother's age. We also related the ages of brothers. The pregnancies in a mother occur regularly every three years. Only when the child reaches a certain stage of development the mother is again fecundated for the next delivery. In the meantime she resorts to contraceptive herbs. In case of pregnancy before the allowed time they eliminate the child at birth. This practice is perfectly logical the mother having no possibilities of raising and feeding two children with a small difference of age between them. For the same reason a mother eliminates the weakest child if twins are born. The law of the jungle is many times cruel but good sense always prevails.

    1 ) Malocclusion index:
    a) N.I.D.R. index.
    b) Canadian index - items 16 to 24.
    2) Goniac Angle measurement.
    a) Pedersen's index.
    b) Broca's index.
    c) Occlusal surfaces:
    c.1) Frontal plane (anterior view) -
    c.2) Sphere - anterr.
    c.3) Sphere - posterior.
    d) Attritional symmetry. e) Cusp permanente.
    Goniac Angle:

    lt. was measured with a protractor. The mandible's posterior border, body and ramus were appreciated externally by palpation, with possible margin of error.

    Jaw Relationship:

    The profile was evaluated trying to detect the antero-posterior jaw relationship. When the jaw relationship appeared normal, it was noted as I When it looked like a mandibular retrusion, it was noted as I I. When it looked like a mandibular protrusion it was marked as III. This appreciation was done by observing the soft tissues and profile without teleradiography and it was subjected to error

    Cervical abrasion:

    Cervical abrasion was inspected in the cervical area, on labial of both upper and lower teeth. Pedersen's index.

    Occlusal abrasion:

    Occlusal abrasion was evaluated with a generalisation criterium. When the majority of teeth inspected showed a definite aspect it was noted down like that for the whole mouth.

    Frontal Plane
    Abrasion form of the incisal edges of incisors and canines (front view) was observed. lt was noted down as straight when the abrasion form was a straight line; negative when it showed a curve with inferio axis; positive when the curve had a superior axis.

      Occlusal Sphere
    Occlusal abrasion in the whole mouth doesn't take place on a fiat plane but it appears, on a curve, named "occlusal sphere". On the lower jaw, the prominence or peak produced by the abrasion on a curved surface was observed. When the prominence was located on the lingual side of the occlusal face, the "sphere" was labelled as negative. When the prominence was situated on the buccal side, the "sphere" was positive. The occlusal sphere was analysed in two different areas-. anterior and posterior. The separation between the two areas was located on the distal faces of lower first molars.

    Attritional Symmetry:
    Both the left and right sides of the dental arch were observed to determine whether the occlusal abrasion was symmetrical or not.
    Cusp permanence:
    The criterium adopted was of generalization. When most of the cusps were eliminated by abrasion, the notation was: no cusps.

    Proximal abrasion:

    In those cases in which models were obtained, abrasion of the proximal faces between first and second lower molars was measured. lt. was scored "0" , when the abrasion was imperceptible; I, when the added abrasion of both faces (distal of first moral and mesial of second molar) was O,5 to 1,5 mm.; 2 when it was over I,5 mm. The measurement was done on the more abrasioned side.


    Missing Teeth:

    A tooth was considered missing when it was lost or when only the roots remained in place.

    Note: Criteria and indexes of international use are not explained here because they can be found in the references,


    150 individual charts 507 photographs:

    lntraoral: 301 Profile: 125 Frontal: 81

    28 models of typical cases.

    Note: Radiographs were not token because it was impossible to transport heavy equipment.


    Malocclusion prevalence

    N.I.D.R. INDEX

    I: Crowding 48 %
    II: Distocclusion 21,7 %
    I I I: Overbite 19 % IV:
    Overjet 36 %
    Total prevalence 71 %


    Angle's Class I: 77,7 %
    Angle's Class 2: 22,3 %
    Angle's Class 3: "0 " %
    Crowding: 52,7 %
    Inclined teeth: 10%
    Crossbite: 23,6 % Overjet: 20,9 %
    Overbite: 17,6 %
    Open-bite: "0 "Diastemas: 7,4 %
    Edge to edge-bite: 12,8 %
    Mandibular shift: 2,7 %
    Impacted teeth: 2 %
    Atrophied teeth: 2 %
    Non dental congenital defects: "0 "%

    Supernumeraries: 2 %
    Total prevalence: 71 %

    Note: Anomalies are superimposed. Note: Both N.I.D.R, and Canadian indexes are based on different criteria. The identical final results are purely coincidental.

    Prevalence of malocclusion in Yanomamis is very close to that found in civilized people We believe that in a larger sample Angle Class III would had been found also. Non-dental congenital defects were absent because after birth, mothers eliminate defective or abnormal children. Anyway the general pattern is quite similar but the problems are present with less severity. For instance: we didn't find overjet with lip interposed. As for crowded teeth, very few had a discrepancy larger than the width of a lower incisor. We think that Begg 16 found a quite lower prevalence (l4 %) because the australian aborigines he examined belonged to a primitive racial group with primitive morphological features. In fossils of man ancestors -hominids and pre-hominids- it seems to be no malocclusion. If we accept that the lower masticatory activity has had influence in the evolution of our civilized men's teeth, it was to be expected that the Yanomamis had a substantially lower prevalence of malocclusion. The Yanomamis, as amerindians, were isolated and established in communal group since 20.000 years ago. Contrary to our civilized peoples, they didn't noticeably change their feeding habits. All this lead us to think that malocclusion is a genetic force inherent to each people which follows the morphologic evolution of men and is independent of masticatory activity.


    Jaw relationship:

    95 % apparently presented a good jaw relationship (I). Even in Class II cases, the majority seemed to be purely dental. At least we can state that we didn't see marked macrognatias or micrognatias.

    Discussion: We understand that the good jaw-relationship and the little variation of goniac angle are due to the fact that the Yanomamis belong to a definite ethnic group without mixture, This is the reason of not finding severe malocclusions, like Class II with lip interposition. The absence of great mandibular angles explains the small prevalence of "mordex apertus".

    Cervical abrasion:

    We didn't find cervical abrasion in any teeth.

    Discussion: The total absence of cervical abrasion in the yanomamis lead us to believe that this phenomenon, so common in men of our civilization, is caused by tooth brushing. The yanomamis had no brushing habits.

    Occlusal abrasion: (attrition - Broca y Pedersen index )

    Occlusal abrasion is the result of a vigorous chewing with very hard or abrasive foods. With age, abrasion becomes more intense.

    Discussion: We think that this physiologic abrasion is beneficial to dental health. lt. eliminates sulci and fissures which are major places of caries incidence. lt. reduces the height of tooth crown, lowering the leverage action (or "force momentum"), permitting a better self cleaning effect of foods and gum stimulation. lt. eliminates also occlusal traumas. Comparing with results found by Beyron and Barret ) the Yanomamis have a slightly lower occlusal abrasion.

    Occlusal frontal plane:

    When overjet was small incisors and canines showed an abrasion pattern proportional to posterior teeth. Straight plane Superior negative curve 33 % of cases Inferior positive curve 66 % of cases

    Discussion: The occlusal frontal plane with a curve negative superior and positive inferior is produced by masticatory activity This abrasion is proportional to age. In older people even an open bite was found. Craft habits produced irregular and characteristic abrasions.

    Occlusal sphere:

    Occlusal sphere was characterised in 100 % of cases by a negative curve in the anterior area and a positive curve in the posterior area.

    Discussion: The occlusal sphere has a positive curvature (with superior axis) in a young mouth without abrasion. As abrasion progresses with age, curvature of the occlusal sphere changes in the anterior and middle areas of the mouth, from first molars frontwards (anterior area). The posterior area (second and third molars) very seldom changes its original curvature. Negative curve sphere in the anterior area closely follows the individual masticatory pattern. In tribes of aborigines with primitive feeding habits, occlusal sphere in the anterior area becomes a negative curve at an early age. With the advent of more civilized feeding habits and a softer diet, groups of aborigines and "mestizos" (half blood indians) in contact with present day civilized man delay many years to adquire a negative curve in the anterior area.

    Attritional symmetry:

    Attrition was symmetrical in most normal mouths. There was attritional asymmetry in every case with crossbite. In senility, with occlusal interferences eliminated by abrasion, there was a strong tendency towards symmetry.

    Discussion: Problems of attritional symmetry are caused by occlusal interferences, early loss of teeth or craft activity.

    Cusp permanence:

    Every adult individual had all the cusps eliminated by abrasion. Only the prominences or peaks of the occlusal sphere were observed. In senility there was a tendency towards total flattening.

    Discusión: Cusp elimination my physiologic abrasion doesn't impair masticatory efficiency. Abrasional edges of enamel became as sharp as a razor's edge. lt. would seem then that the objective of cusps is mainly to guide teeth to achieve occlusion.

    Proximal abrasion:

    Adolescents - o Adults + o Matures - 1 Seniles - 2

    Proximal abrasion found in Yanomamis was not as accentuated as that found by Begg among Australian aborigines. Abrasion was more intense between 1 st and 2 nd molar and between 2 nd and 3 rd molar. In anterior teeth proximal abrasion was negligible.

    Discussion: It is our belief that space created by proximal abrasion is used by the third molars and not by canines and incisors. When anterior teeth need more space, proximal abrasion is not enough. Crowding cannot be compensated in large extent by physiological proximal abrasion.

    Caries and Missing Teeth:

    60 % of missing teeth were due to injury or crafct. Only 40 % were lost by caries.

    Discussion: In spite of the lack of a thorough examination, it was evident that caries incidence was significantly lower than in present day civilized men. Neither water nor enamel mineralization were analysed. Apart from those two factors we believe that physiological occlusal abrasion (eliminating sulci and fissures) produced by the intense masticatory activity, with its self cleaning and anti-plaque effects, has appreciably influenced caries

    Periodontal health:

    Discussion: A leading epidemiologic paper, came to these conclusions:

    I ) There is a prevalence of almost 100 % of periodontal disease in developing countries.

    2) There is a predominant and consistent association between plaque and/or calculs amount and severity of periodontal disease.

    3) There is no consistent relationship among periodontal status and the factors sex-roce-ethnic group, and nutritional status, when compared in persons with similar age and oral hygiene status.

    Yanomamis apparently are not excluded, provided their periodontal status is compared with persons of good oral hygiene habits. Even as the Yanomamis don't have oral hygiene habits, their vigorous chewing self cleanses their teeth. Elimination of occlusal traumas by abrasion and reduction of tooth crown height, allowing better stimulation of gums in mastication, less plaque formation and lower "momentum" of force, could have contributed to the better periodontal "status" found in the Yanomamis.


    1) Influence of mastication in the evolution of human teeth doesn't seem to be preponderant.

    2) The only visible reason to explain the lack of cervical abrasion among Yanomamis was the no use of a toothbrush.

    3) Physiologic occlusal abrasion increases with age, considerably reducing tooth crown height. This enhances self cleaning and masticatory stimulus of gums.

    4) Physiologic occlusal abrasion eliminates tooth cusps without impairing masticatory efficiency.

    5) Occlusal interferences generate attritional asymmetries,

    6) Physiologic proximal abrasion has little influence if any in anterior crowding.

    7) Physiologic occlusal abrasion and vigorous mastication are beneficial to periodontal health.

    8) In every dental observation made there was no significant difference between women or men.


    150 Brazilian aborigines of the Yanomami family were examined. These indians still live isolated in the jungle and have dietary and hygienic habits of primitive men. When compared with people of present day civilization it was found a slightly lower prevalence of malocclusion; marked occlusal abrasion; lower incidence of periodontal disease; lower incidence of caries and total absence of cervical abrasion.


    Nous avons examiné 150 aborigènes brésiliens de la falmilie des Yonomami, qui vivent à l'heure actuelle isolés dans la jungle avec les coutumes alimentaires et hygiéniques de l' homme primitif. En les comparant avec des personnes de notre civilisation, nous voyons une fréquence de malocclusion légèfement moindre, de meulage occlusal accentué, de maladies periodontales et de caries moindres et une absence totole d'abrasion cervicale.

    Es wurden 150 brasilianische Eingeborene der Familie der Yanomamis untersucht die noch isoliert im Dschungel leben und eine Lebensweise wie der primitive Mensch bewahren. Im Vergleich mit Personen aus unserer zivilisierten Welt sind etwas weniger Okklusionsanomalien, eine stärkere Abnutzung der Kauflächen, weniger Parodontalschäden und weniger Kariesanfoll festgestelltworden und dazu ein absolutes Fehlen von Abrasion an den Zahnhälsen.Tipical occlusal abrasion.
    Look Yanomamis índians photography and sumary





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    Foster, Leslie W.: "Dental Conditions in White and Indiain Children in Northern Wisconsin". J. A. Dent. Ass., 29, 2251-2255, Dez. 1942.

    Goldstein, M.: "Caries and Attrition in the Molar Teeth of the Eskimo Mandibule. Am. J. Phys. Anthrop., 16, 1932.

    Lundstron, A.: "An Anthropological Examination of a Grup of Medieval Danish Skulls, with particular Regard to the Jaws and Occlusal Condition". Acta Odont. Scand., 11.

    Lysell, L.: "Qualitative and Quantitative Determination of Attrition and the Ensuing Tooth Migration". Acta Odont. Scand., 16, 1958.

    Mussolini, G.: "Evolução da Raça Humana". Editora Nacional, 1969.

     Other publisched an picturesof the  Yanomami Indians