DENTAL MORPHOLOGY AND PATHOLOGY OF PREHISTORIC GUAM

¹ Captain, Dental Corps, U. S. Army

The ancient inhabitants of Guam subsisted exclusively upon the flora and fauna of their insular habitat. Their food consisted of fish, some fowl, bread-fruit, taro, yams, rice, bananas, coconuts. Screw pine and sea-weeds served as relishes. Bread-fruit and fish were dried and stored. As throughout the tropical Pacific, they cooked the food in pits in the earth with heated stones. They did not eat to excess nor did they use fermented beverages.

Betel nut was the narcotic to which they were strongly addicted. This is a cultural trait of wide Oriental distribution. The nut used is from the betel palm, Areca catechu. A part of the nut is wrapped with a few leaves of betel pepper, Piper betle, and the whole sprinkled with a pinch of lime, the latter secured by burning coral. This has a marked stimulant effect. The betel juice also produces a soluble red pigment, which colors the saliva, lips, and mouth a rich red, and gradually but permanently discolors the teeth.

Morphological features of note: The cervical margin of the enamel streams into the bifurcations, particularly of the inferior second and third molars, terminating in an acute point. Occasionally beyond this point, a detached enamel pearl is found. This feature is absent in Caucasians, and more prominent in many American Indian tribes than in this group.

A peculiar feature of these teeth is a corrugation of the enamel on the buccal aspect of the superior premolars and molars. It consists of a horizontal, rounded, unfaulted, groove with a low ridge above and below it. The cervical ridge may be interpreted by some as a cingulum.

Marginal ridges on the lingual aspect of the superior incisors are not prominent in this series, being present in moderate degree only on some 20 per cent.

The cusp formula of this group tends to be 4-4-4/5-4-4. The mandibular first molar is constant; the second molar is quadricuspid in 80 per cent; the maxillary third molar is the most variable. Such a cusp formula is not indicative of a primitive race. There is a decided tendency to diminution in the size of the maxillary third molar. In many skulls it is a mere abortive vestige; frequently it is not erupted. There [See figure in the PDF file] [See figure in the PDF file] are some males with large angular jaws, and large teeth with accessory roots.

The normal occlusion is characterized by a slight procumbency of the incisors, with attendant edge-to-edge occlusion, and slight inter-digitation of the posterior teeth—prosharmosis. The masticatory musculature was weak. Malocclusion occurred in 15 per cent. Impaction of mandibular third molars was frequent.

The mental foramen was below Pm₂ in about 80 per cent.

The palate is short, broad, and roundish; 95 per cent are brachyuranic. The average dental index is 42.6. The group tends to be mesodont. The average gnathic index is 98.9—mesognathous. Many of the crania, particularly females, present an apparent prognathism. This is sub-nasal, between the akanthion and prosthion, giving a Negroid fullness to the oral region. There are marked sexual differences in the group; otherwise homogeneity characterizes it. The somatological characters herein described point unmistakably to Mongoloid affiliations.

The teeth are well formed; but 5 per cent evidence slight developmental disturbance. Ethnic deformation was practised to a limited extent by filing a lattice design on the facial surfaces of the six superior anterior teeth. Staining the teeth an orange to black color was customary.

Betel-nut chewing was universal. Its deleterious effects on the teeth were permanent discoloration of the enamel on the facial surfaces particularly, and predisposition of investing dental tissues to degeneration. The betel-nut concoction, because of its lime content, produced enormous accretions on the teeth, which, through impingement on the gingivae and alveolar process, caused chronic irritation and inflammation. The repeated and long continued action of the narcotic bolus furthered the chronic inflammatory process.

The betel-nut habit, together with a soft diet requiring but little mastication, were the primary factors in producing a high incidence of periodontoclasia—chronic destructive degeneration of the investing tissues of the teeth—which eventuates in exfoliation. Practically all females and 65 per cent of males beyond forty had teeth involved by periodontal disease. The third molars were affected most frequently. No person under thirty had lost any teeth at decease. Periodontoclasia was the major cause of loss in later life.

Dental caries occurs in 18 per cent of the skulls. Sixteen per cent evidence periapical lesions, secondary to caries, attrition, and fracture. Impacted third molars caused extensive disturbance of the tissues. Serious lesions of the palate and nose of some skulls were evidently resultant from yaws.