23
those >35, expesed and unexposed. were free of
clinically detectable peridontal disease. In the
(open circles, exposed people; closed circles, unex-
held in position by the gingival attachment.
3-year age group with exposed and unexposed
people combined. The trend of each criterion with
aged, many of the remaining teeth were simply
Almost all the Rongelapese exhibited marked
xerostomia. The oral mucosa felt damp but not
wet. During the dental examination, manipulation of the tissues by mouth mirror and explorer
failed to stimulate the flowofsaliva. For pH read-
ings, the paper strip had to remain in contact with
the floor of the mouth for 25 to 30 sec in order to
absorb sufficient saliva. In most instances it was
dificult for the subject to produce the 5 ml of
saliva necessary for pH determination in a period
<(10 to 15 min. The #H values ranged from 6.0 to
7.5, with an average of 6.3
Utirik Population
The Utirik population exhibited oral findings
similar to those of the Rongelapese. Their standards of oral hygiene were somewhat superior, but
the incidence of peridontal disease and caries in
adults was practically identical. In the Uunk
children less evidence was seen of bunching ofthe
lower anterior teeth, and jaw development was in
harmony with general body growth.
Conclusions
These examinations led to the following conclusions.
1. There was no significant difference in either
caries rate or incidence of peridontal disease between the exposed and the unexposed people of
Rongelap. The level of oral hygiene appeared to
be somewhat better in the children examined at
M ‘uro and at Utirik, but the incidence of caries
w
posed people) to show the spread of the data, and
the mean values are also plotted (squares) for each
increasing age is represented by line of approximate best it by eve. The values of the criteria
generaliv either increase or decrease with increasing age. Many changes, such as greying of the
hair, batding, arteriosclerosis (peripheral and
retinal}, and skin looseness and retraction, are not
appeciably manifest in the Marshallese untl after
age 35 to 40. There is a tendency for values of
criteria such as blood pressures, greying of the
hair. loss of visual acuity, and accommodation to
level off, or even to show- :ghtly reduced values
in the oldest groups. The number of people in
these groups Is too small to makethis observation
certain. However, America: -itatistics on blood
pressure (systolic and diastolic) also show a plateau
effect beyond about 60 years of age and evena
slight tendency to lowering of blood pressures be-
yond this age.°” By the age of 65 to 70, aecus
senilis in all Marshallese showed a 44 change
and, therefore, the plateau was at a maximum.
Some curves showed lower maxima. For example,
baldness in women showedonly a 33% maximum,
and arteriosclerosis of the retina only 45%. The
differences in maxima probably were due largely
to differences in the degree of change associated
with the various criteria but also partly to the
arbitrary nature of the scoring. The sexual differences in hand strength and baldness were ex-
pected. In the neuromuscular function test, slight
muscle fatigue may have been a factor in the lower
female scores, necessitating separate evaluation.
ibout the same in the two groups, and higher
than in the Rongelapese children.
2. The poor oral hygiene generally observed in
the Marshallese people had its usual results: a
high caries rate in teen-age children; severe peridontal lesions in adults (heavy calculus, loss of alveolar bone); and edentulous mouthsin the aged.
3. No difference was perceptible in the clinicat
appearance of developing dentition amongthe ex,
posed children, the nonexposed, and those born to
irradiated parents.
STUDIES OF AGING CRITERIA
The results of aging criteria studies are plotted
in Figures 13 to 31. Individual readings are plotted
CT
7
Y
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T
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if
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'
'
*=UNEXPOSED
°=MEAN BOTH GROUPS
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eo
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99 t
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70
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oy DO
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ac -
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60
AGE - YRS
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70
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80
Figure 13. Skin retraction time, 1958-1959.
0
(