98

Oral Findings of Wild Japanese Monkeys

JuN ISHIKAWA and KEISUKE YAMAZAKI Tokyo Medical and Dental University

SUGIO HAYAMA Kyoto University

The incidence and severerity of oral diseases in wild Japanese monkeys have never been adequately documented. A group of wild Japanese monkeys (Macaca fuscata fuscata) consisting of forty-nine individuals was captured on Shodoshima island and fed on a natural raw diet in a very large open cage for six months before examination. The forty-nine monkeys examined were classified into four groups in respect to dental age.

Group I deciduous dentition (0-1 year) 12 animals Group II mixed dentition (1-5 years) 13 animals Group III permanent dentition (5-9 years) 13 animals Group IV permanent dentition (9-23 years) 11 animals The oral condition of these monkeys was investigated as a part of the

general physical examination carried by the Japan Monkey Centre. This paper is a part of the comparative study of the oral condition among wild and artificially fed monkeys and the purpose of comparison is to clarify whether artificially produced food has an etiological role in major dental diseases or not.

Both tooth and periodontal tissue examination were carried out in this study. P-M-A index, gingival pocket-depth, tooth mobility, calculus and debris indices, tooth caries and so on were investigated and recorded. To tranquillize the animals, a tranquillizing agent (produced by Shionogi Seiyaku) was given before experiments.

The results of this study were as follows:

1. The conditions of the periodontal tissues: P-M-A index, a quantitative clinical method of assessing gingival in-

flammation, was used for evaluating gingivitis in upper and lower anterior regions. The following table show the number of animals with gingivitis and the average score of the P-M-A index.

The incidence of gingivitis was high, but severe gingivitis was not found. The gingivitis was confined to the papillary and marginal area and never extended to the attached gingiva. The severity of gingivitis increased with age except in the mixed dentition group. The P-M-A index was higher in the upper region than in the lower. The depth of gingival pocket was

99

Lower

Group

I

II

III

IV

I Upper and Lower ~ U)per

No. showing Average No. showing Average gingivitis score of gingivitis score of

'(mad Percent,!P-M-A index(and Percent index

. . . . 6

2__ 2.3

(50.0%)

12 3.9 (92.3%)

11 3.8 (84.6%)

8 4.9 (72.7%)

6 (50.0%)

11 (84.6%)

11 (84.6%)

8 (72.7%)

1.8

2.2

3.2

4.0

No. showing gmglvms

(and Percent)

Average score of

P-M-A index

2 (16.7%)

6 (46.2%)

4 (30.8%)

5 (45.5%)

0.3

1.8

0.5

0.9

0.5 to 2 .0mm and this value may be in te rpre ted as normal value. T o o t h mobili ty which indicates the loss of alveolar bone was not observed in pe rmanen t teeth.

2. The cleanliness of their mou th was evaluated from Ora l Hygine Index, a method of assessing the amoun t of food debris and calculus accumula t ion on representat ive teeth surfaces. The average scores of this index were 0.04 in group I, 0.8 in group II , 1.3 in group I I I , and 1.5 in group IV, which were insignificantly less than that of men, bu t increased with age. Calculus

accumula t ion was found in four monkeys of the forty-nine individuals.

3. Too th caries were examined by a sharp explorer with special a t tent ion, bu t no caries was found.

In conclusion, oral conditions of forty-nine Japanese monkeys in the wild state were examined. The i r mouths were ext remely clean and debris and calculus was much less than in humans, and tooth caries and severe per iodonta l destruct ion (alveolar pyorrhoea) was not found at all in their mouths except ing slight marginal and papi l lary gingivitis.

Fur the r investigation compar ing the oral conditions of wild and captive monkeys is going on.