ヘルスサイエンス・ヘルスケア

Volume 6，No.1（2006）

Half century-trends in caries prevalence and tooth retention inJapan at a glance
Yuichi AndoIntroductiontion Survey).

Ministry of Health, Labour and Welfare in Japan・Sampling procedure (Figure 1) is as follows:

has conducted National Survey of Dental Diseases(i) Select districts for National Livelihood Sur-

once in 6 years since 1957. The recent survey (thevey by stratified random sampling of the9th) was conducted in 2005. The surveys basicallyNational Census unit areas, and (ii) select dis-employ the same method which is suitable to eval-tricts for National Health and Nutrition Sur-uate changes in data.

vey by random sampling of further 300

Thus, this article overviewed the changes inareas.

dental diseases in Japan for almost a half century(iii) Districts for National Survey of

Dental Diseases is the same as those forusing these data.

National Health and Nutrition Survey.
・The subjects are residents over the age of 1
Methodwho live in each district.

１．Data Source (Summary of National Survey of・Dentists, the majority of them are general

Dental Diseases)

practitioners, perform oral examination.

Main features of National Survey of Dental

２．Analytical method

Diseases are as follows:

Average number of present teeth per person

・The population is community dwelling Japan-andese people.

itscomponents(averagenumberofsound/decayed/filled teeth per person) of decidu-

・ The survey is conducted once in 6 years.

ous teeth (1 to 14 years old) and permanent teeth

・The survey is conducted along with National
Health and Nutrition Survey (National Nutri-【著者連絡先】〒 351-0197 埼玉県和光市南 2-3-6
国立保健医療科学院・口腔保健部
口腔保健情報室長 安藤雄一
（深井保健科学研究所客員研究員）
TEL：048-458-6283 FAX ： 048-458-6288
E-mail： andoy@niph.go.jp

Fig.1― 23 ―

Structure of NSDD

Half century-trends in caries prevalence and tooth retention in Japan at a glance（ above 5 years old） were calculated by age forthe past half century.

each year based on the survey results. These 4

１．Deciduous teeth (Figure 2）

indices had a following relationship:

Prevalence of dental caries was very high fromaverage number of teeth per person

1957 (the first survey) to 1970's.

= average number of sound teeth per person

However, it

decreased in younger children with the age of 1 to+ average number of decayed teeth per person

5 years old in 1980's, and has decreased in children+ average number of filled teeth per person.

over the age of 6 after 1990's.

Accordingly, a graph which indicated the aver-

The number of filled teeth was rare in the first

age number of present teeth per person by age

survey (1957) but the rate of filled teeth has gradu-

for each year was made.

ally increased afterwards.
２．Permanent teeth (Figure 3)

Results

Unlike deciduous teeth, prevalence of dental

Figures 2 and 3 show average number of decid-caries of children had increased after the first sur-uous present teeth (Figure 2) and permanent pre-vey (1957) until 1980's. However, it tends to subse-sent teeth (Figure 3) per person by age between

quently decrease and the trend still continues.

1957 and 2005 as well as its components (sound/Since the first survey in 1957 as in the case ofdecayed/ filled teeth), respectively. These graphs

deciduous teeth, the rate of filled teeth hasoutline the changes in dental disease in Japan forincreased while the rate of decayed teeth hasFig.2

Trends in Composition of Primary Present Teeth（1957-2005）― 24 ―

ヘルスサイエンス・ヘルスケア

Volume 6，No.1（2006）

Fig.3 Trends in Composition of Permanent Present Teeth（1957-2005）

dental health in Japan was management of thedecreased.
Average number of present teeth per person

increasing number of decayed teeth among children, and caries treatment was given priority overtends to increase in the elderly after 1980's.

prevention of dental caries. Japan had a relativelyDiscussion

sufficient number of dentists and established theThis article described changes in prevalence ofschool oral examination system, based on national

dental caries and tooth retention for almost a half

health insurance service which covered all Japan-century in Japan. There might be a few countries

ese people. Therefore these circumstances seemedin the world that have conducted the national sur-to be advantageous to mainly address dental treat-

vey on dental diseases for a half century. There-ment. This measures produced a results offore, the findings in this article seem to be valuable

increase of the number of filled teeth and decreaseof the number of missing teeth in the elderly todata on a worldwide basis.
Prevalence of dental caries increased in Japan-

some extent, but failed to decrease prevalence ofese children between 1950's and 1970's, which

dental caries. Thus, Japan was said to be one of

mainly resulted from increase of sugar consump-countries where the prevalence of dental caries

tion1). At that time, the most important issue of

was the highest in the world between 1970's and― 25 ―

Half century-trends in caries prevalence and tooth retention in Japan at a glance19802). Subsequently, prevalence of dental caries inReferencechildren tends to gradually decrease, which may

1） Miyazaki H, Morimoto M. Changes in caries prevalence in Japan. European Journal of Oral Sciences
1996 ； 104 ： 452-458.
2） Renson CE, Crielaers JA, Ibikunle AJ, et al. Changing patterns of oral health and implications for oral
health manpower: Part 1, Int. Dent. J. 1985 ； 35 ： 235251.

be influenced by the widespread use of fluoride
toothpaste and fissure sealants. However, scince
the recent 2005 survey results are not sufficient, itis necessary to further promote the preventivemeasures.
As the above-mentioned, the measures against
dental diseases in Japan may not be successful.
However, it will play a role as a reference material
for other countries.

ひと目でわかる日本のう蝕有病状況と歯の保有状況：半世紀の推移
安 藤 雄 一（国立保健医療科学院・口腔保健部口腔保健情報室長）

厚生労働省による歯科疾患実態調査は 1957 年の第１回調査以来、６年に１回実施され、2005 年に最新調査（第９回）が行われた。この調査の方法論は基本的に同じであることから、過去半世紀近くにわたる日本人の歯科疾患の推移をみることができる。そこで、これを一目で概観できるように、乳歯（１〜 14 歳）と永久歯（５歳以上）について各調査年の一人平均現在歯数とその内訳（一人平均健全・処置・未処置歯数）を年齢別に示すグラフを作成した。
このグラフをみると乳歯では、う蝕レベルは初回調査（1957 年）から高く、1970 年代まで続いたが、1980 年代からう蝕が減少傾向にあること、また 処置歯の割合が増えてきたことを一目で確認できる。
一方、永久歯では、う蝕が初回調査（1957 年）以降、1980 年代まで増加し続けたが、その後は減少傾向にが続いていること、処置歯の割合と高齢者の現在歯数が増加傾向にあることを確認できる。
世界的にみて、歯科疾患に関する全国調査が半世紀近く続いている国は数少ないと思われ、その意味でも本論文で示した所見は貴重なデータといえる。また日本の過去半世紀の歯科疾患の推移は必ずしも成功事例とはいえないが、失敗例から得られる教訓という意味では他の国々に参考になる面もあると思われる。

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