論 文 要 等 報 告 書 50 号 学 位 論 文 内 容 要 旨

論 文 要
旨
等 報
書
告
氏
授 与 した 学 位
専 攻 分 野 の名 称
学 位 授 与 の番 号
学 位 授 与 の 日付
学位 授 与 の要件
学 位 論 文 題＼
名
Ha
r
d
j
oS
uk
a
e
n
i
博
歯
50号
博
甲
平 成 '
2 1 年 3 月 2 5 日
医歯薬学嘩合研 究科社会環境生命科学専攻 (
学位規則第 4
条第 1
項該 当)
CARI
ES,CARI
ESRI
S
K,LI
FES
TYLEANDTHEI
RRELATI
ONW汀H
MI
CROBI
ALS
CREENI
NGI
NJ
APANES
EC川LDREN (日本人小児 における
カリエスリスク､瀦蝕と生活習慣ならびに細菌学的スクリーニングの関連)
論 文審 査 委 員
教授 森 田
学
教授 鳥井 康弘
学 位 論 文 内 容
の
要
教授 下野 勉
旨
(
I
NTRODUCTI
ON)
Ake
yc
o
mpo
ne
nto
fa
nyL
Pr
e
Ve
nt
i
vepr
o
g
r
8
mi
8t
OaS
8
e
8
8ape
r
8
0
n'
Sr
i8
ko
fde
ve
l
o
pi
nga
d
i
8
e
a
S
e
.Chi
l
d
r
e
na
r
ei
mpo
r
t
a
nts
ub
j
e
c
t
sf
o
rde
nt
l he
a
lt
a
he
duc
a
t
i
o
nb
e
c
aus
ei
nt
hi
spe
io
r
d,
hepr
t
ima
r
yt
e
e
he
t
upt
r
,t
he
ya
r
ea
thi
g
he
rr
i8
kf
o
re
a
r
l
ybac
t
e
ia
r
lc
o
l
o
ni
z
a
t
i
o
n,a
n dt
he
y
be
g
i
nt
of
o
r
mt
he
i
rl
if
el
o
ngde
nt
a
lbe
ha
io
v
r
s
.
Ac
hi
l
d
'
8mo
t
he
rpl
a
ysav
it
lr
a
o
l
ei
nr
is
a
i
nga
nd
t
r
a
ns
e
fr
r
nghe
i
a
l
t
h･
r
e
l
a
t
e
dha
bi
t
st
Ohe
rc
hi
ld
r
e
n.A
sS
e
8
8
i
ngac
hi
l
d'
8r
i
s
ko
fd
e
ve
l
o
pi
ng
c
a
ie
r
si
Bav
it
a
lpa
r
to
fc
a
ie
r
smanag
e
me
nt
.A c
o
mpr
e
he
ns
i
v
ec
a
ie
r
saS
S
e
S
S
me
ntS
ho
ld
u
c
o
ns
i
de
rf
a
c
t
o
r
sS
uc
ha
8Pas
ta
ndc
rr
u
e
ntc
ri
a
e
se
x
pe
r
i
e
nc
e
,pr
e
s
e
nc
eO
fc
ar
io
g
e
icba
m
c
t
e
r
i
a,
a
ndl
ie
f8
t
yl
e
S
.
Chi
ldr
e
nwhoe
x
pe
ie
r
nc
e
di
nf
ec
t
i
o
nbymut
a
n8S
t
r
e
pt
o
c
o
c
c
ie
a
r
l
yi
nt
he
i
rl
i
ve
s
ha
dg
r
e
a
t
e
rr
i
s
ko
fde
v
e
l
o
pi
ngc
a
ie
r
st
ha
nt
ho
S
eWhowe
r
ei
nf
e
c
t
e
dl
a
t
e
r
.The
s
eba
c
t
e
iaa
r
r
e
i
l
i
t
at
e
a
c
i
do
g
e
ni
c
,
㌔
a
c
i
dur
ica
ndpr
o
duc
e8
Pe
C
i
iCi
f
nt
r
aa
nde
x
t
r
apo
l
y8
a
C
C
ha
ide
r
8t
ha
tf
a
c
ic
m
r
o
b
i
la
a
dhe
r
e
nc
eo
nt
het
e
e
t
h.
The
i
ra
mo
unta
ndv
i
r
le
u
nc
e
,
t
o
官e
he
t
rwi
t
hpa
t
i
e
nt
'
8ag
ea
t
whi
c
ht
he
s
eba
c
t
e
iawe
r
r
ec
o
nt
r
ac
t
e
d,a
r
ei
mpo
r
t
a
ntf
a
c
t
o
r
si
nde
t
e
r
i ni
m
ngt
hec
o
ur
8
eO
f
de
nt
lc
a
a
ie
r
s
.Theg
e
ne
t
i
cd
i
ve
r
s
i
t
yo
ft
he
s
ec
a
io
r
g
e
icba
m
c
t
e
iai
r
ss
t
i
l
lc
o
nt
r
o
ve
r
s
i
l;S.
a
L
Z
Z
ut
a
BShasbe
e
nS
ho
wnt
ob
emo
r
epr
e
va
l
e
ntwhi
l
eS.sobm'
nusi
8mo
r
eC
l
o
s
e
l
yr
e
l
a
t
e
dwi
t
h
L
t
a
DS
.Ho
we
ye
r
,i
ti
sdi
f
Rc
ltt
u
oi
de
nt
i
y
f
hi
g
hc
a
ie
r
sa
c
t
i
it
v
ya
nds
e
l
d
o
mf
o
undwi
ho
t
utS.mz
c
a
r
i
e
sr
i8
ko
fc
hi
l
d
r
e
no
nt
heba8
i
80
fo
r
l･
a
e
xam
i na
t
i
o
no
ly
n
.Ma
nybac
t
e
io
r
l
o
g
i
c
a
lc
a
ie
r
8
a
c
t
i
it
v
yt
e
s
tha
vebe
e
nde
ve
l
o
pe
,
dt
oa
v
e
r
tt
hi
革d
i
f
Gc
ul
t
y
.The
o
r
e
t
i
c
a
l
l
y
,de
nt
a
lpl
aq
ues
e
e
ms
t
obeapa
r
t
i
cu
la
r
l
ya
ppr
o
pr
ia
t
eme
ho
t
dbe
d
auS
et
het
o
o
hs
t
ur
f
a
c
ec
o
nS
t
i
t
ut
e
st
hena
t
wa
l
ut
a
L
2
8
.TheCa
r
∼
i
o
8
t
a
tt
e
s
ti
SaC
a
ie
r
sr
i
s
kaS
S
e
8
8
me
ntt
O
O
lt
ha
tc
o
ldpr
u
e
di
c
t
ha
b
i
t
a
to
fS.RZ
c
hi
l
d
r
e
n'
SC
a
ie
r
Sr
iS
k.TheCa
iO
r
s
t
a
tme
di
n c
u
o
nt
ins20% o
a
fs
uc
r
o
s
ea
ndt
woki
ndso
fpH
i
nd
i
c
a
t
o
rt
os
ho
wv
i
S
ua
ll
yt
hep,
H de
c
r
e
as
eC
a
us
e
dbym
ic
r
oo
r
g
a
ni
s
msi
nt
hepa
t
i
e
nt
'
8pl
aque
S
ampl
e
.Mo
r
e
o
ve
r
,al
o
ng
it
ud
i
nl
as
t
ud
yi
8mo
r
ea
ppr
o
pr
ia
tef
o
rf
o
uo
wi
ngt
hec
ha
ng
e
80
f
de
nt
lpr
a
o
g
r
e
8
S
i
o
n,
o
r
lhyg
a
i
e
neo
fc
hi
l
d
r
e
n,
a
ndl
o
o
ki
ngf
orpr
e
di
c
t
o
r
80
fc
a
ie
r
s
.
(
MATERI
ALSANDMETHODs)
At
o
t
a
lo
f283c
hi
l
d
r
e
nwe
r
eS
e
l
e
c
t
e
dbas
e
do
nt
he
s
eC
r
i
t
e
r
i
a:t
he
yhadde
nt
a
le
xa
m血a
t
i
o
n,
ha
df
il
l
e
do
utt
heq
ue
s
t
i
o
nna
ir
eandhadpa
r
t
i
c
i
pa
t
e
di
nCa
io
r
s
t
atm
ic
r
o
b
i
l8
a
a
mPl
ing･The
d
e
nt
a
le
xa
mi
na
t
i
o
nswe
r
ec
a
ie
m
do
叶b
yt
heS
a
mede
nt
i
s
tWi
h ade
t
nt
l mi
a
r
r
o
ra
nde
x
pl
o
r
e
l
･
unde
rna
t
ur
ll
a
i
ht
g
.TheS
a
mede
nt
i
s
tal
s
oC
O
l
l
e
c
t
e
dpl
a
que8
amPl
e
Sf
ro
mt
hema
x
i
ll
ar
y
buc
c
a
Lc
e
vi
r
c
ls
a
ur
f
a
c
e
Sus
i
ngS
t
e
il
r
ec
o
t
t
o
n･
t
i
ppe
da
ppl
ic
a
t
o
r
s
.A de
nt
l hyg
a
i
e
ni
s
tt
he
n
i
nc
uba
t
e
dt
heCa
r
i
o
B
t
a
tme
di
um a
t3
7oCf
o
r4
8ho
ur
s
.I
nt
hepr
e
s
e
ntS
t
udy
,t
heCa
iO
r
S
t
at
.
0a
ndl
･
5
)a
n dhi
g
hr
i
s
kg
r
o
up
r
e
s
ul
twe
r
eg
r
o
upe
da
c
c
o
r
di
ngt
ol
o
wr
i8
kg
r
o
up(
CAT0,
0.
5,1
(
CAT 2.
0,2.
5a
nd3.
0
)
.A 8
t
r
uC
t
ur
e
dque
s
t
i
o
nna
ir
ewasC
O
mPl
e
t
e
dbyt
hemo
he
t
ro
ft
he
c
hi
ldr
e
na
te
a
c
h8
C
r
e
e
ni
ngt
oe
va
luat
ewhi
c
hf
a
c
t
o
r
sr
e
g
a
r
di
ngt
hec
hi
ld
r
e
n'
Sl
i
eS
f
t
y
l
emade
t
he
mS
uS
C
e
Pt
i
bl
et
oc
a
ie
r
S
･
Thec
hi
･
S
q
ua
r
ea
nd8
t
ud
e
nt七
･
t
e
S
tWe
r
eus
e
dt
oa
na
lyz
eS
i
g
ni
ic
f
a
nt
r
a
nki
ngo
fc
hi
l
d
r
e
n･
Sl
if
e8
t
yl
e
Sa
ndho
wc
hi
l
d
r
e
n'
l
i
e8
f
t
y
l
e
8a
ndc
a
r
i
e
sr
i
s
katt
hel
･
5･
ye
a
r
･
o
l
d
,a
nd3･
5
･ye
a
rpe
io
r
d.Ⅰ
na
pe
io
r
dwo
ldi
u
nf
lue
nc
ec
hi
l
d
r
e
n'
8a
ve
r
ag
eC
a
ie
r
sa
tt
he2･
5･
di
ue
r
e
ntS
t
ud
yo
f4
9
9c
hi
l
d
r
e
n,o
nehundr
e
dc
hi
l
d
r
e
nwe
r
er
a
ndo
ml
yS
e
l
e
c
t
e
df
r
o
ml
o
wa
nd
hi
g
hc
a
ie
r
Br
i8
kc
hi
l
dr
e
n.To
t
a
l
l
y
,200c
hi
ldr
e
nwe
r
es
e
l
e
c
t
e
df
o
rm
ic
r
o
b
i
a
18
C
r
e
e
ni
ng･Si
mpl
e
random sampling was performe<:l using three-colored dices thrown at the same time.
Microbial screening of their Cariostat-inoculated plaque sample was done for detecting the
presence of S.m utans and S.sohrin us on the basis of caries activity. DNA extraction was done
following a protocol for Gram positive bacteria. Bacterial DNA detection was initially done
through a PCR technique 'using universal primers to check for the presence of bacteria. The
PCR reaction mixture. (20 11]) contained of 2.0~ III of lOX PCR buffer, 1.6 III of dNTP mixture,
and 0.1111 of Taq DNA polymerase (Takara TaqTM) , 5.9 III of distilled Water (GIBCOTM), 10 J.ll
template solutions and 2 III each of the primer pairs. Besides the samples, purified genomic
DNA from S. mutans ATCC 25175 and S. sohrinus ATCC 33478 were used as positive
controls in each experiment. The PCR amplification was performed under thermal conditions
specific for both bacteria. The PCR products were analyzed by electrophoresis on a 1%
agarose' gel in Tris-acetate-EDTA running buffer (pH 8.0). To estimate the size of the PCR
products, a 100-bp DNA ladder and 0 X174 RF DNAlHae III fragment were included in each
gel as markers. After staIning with 2%ethidium -bromide, the newly synthesized DNA
fragment was visualized under ultraviolet light. PCR products were verified at least two
times under the same conditions, in accordance to the presence or absence of DNA bands.
(RESULTS)
a. Cariostat score during the early childhood period showed the current oral condition and
succeeded in predicting oral condition at a later a g e . '
.
b. Childrep.'slife styles af~ect caries risk.
c. Cariostat test is useful ina'ssessing caries increment.
d. The presence of S. sohrin us was more closely related with high caries activity and high df
numbers.
(DISCUSSION)
Knowledge about all of the risk factors in children is important for determining the optimal
period for prevention and interceptive treatment. Caries experience and caries activity in
children tend to increase as their age increases. Before a carious lesion actually develops,
caries risk assessment is recommended. For life style at the 1.5-year-old period, a strong
difference of the mean number'of carious teeth was found between children with and without
pre ,chewing habit. This negative parental behavior plays a role in early vertical transmission
by salivary contact. The effect of breastfeeding to children's caries occurrence is still
controversial. A few specific case studies have linked prolonged ad libitum and nocturnal
breastfeeding to early childhood caries. For life style at the 2.5-year-old period, children with
high sugar intake were clearly associated with an increase in caJ,'ies at the 3.5-year-old
period. Children with irregular snacking had a significant influence on children's decay rate.
Initial PCR using universal primers showed a band indicating the existence of some bacteria
throughout the whole plaque samples. It has been suggested that these bacteria are
generally established in the oral cavity of children before 3 years old. Our PCR results show
that·these cariogenic.bacteria are more prevalent in,a child who has high caries risk than
low caries risk, and agrees with several previous studies' This finding also associated the
presence of cariogenic bacteria in children with high number of decay. S. sohriIius and the
presence of both S. muta.ns and S. sobrinuswere more likely detected in children in the.high
caries risk group and had high number of df. S. m utans is undoubtedly one of the most
acidogenic of the species found within the dental plaque, being capable of producing acid
from fermentable carbohydrates at a higher rate and over a much greater pH range than
most other streptococci.'Moreover, the presence of S. sobrinus was more closely related with
high caries risk activity and high df numbers. Based on' these studies, we summarize that;
Carisotat score at early childhood not only show the present oral condition but also could
predict their oral condition at a later age. Children's ).ife styles change according their age
and can potentially affect children caries status. The Cariostat test is useful in assessment
and predicts children caries risk. OUf microbial screening result show that the presence of
Streptococcus sobrinus is more closely related with high caries activity and high df number
of children.
歯蝕篠息の危険性を嚇蝕羅患または進行拡大す る前に分析 し予防す ることは､と
くにその変化め著 しい小児においては重要なことである｡
嚇蝕は､
養育環境 に大きく
左右 される疾患であ り､小児の口腔内の状態､
歯蝕羅患甲危険性な らびに生活スタイ
ルにまで言及 して予防を行 う必要がある｡
本研究は1
.5
歳,2.
5
歳,3
.5
歳児健診時に保健セ ンターで行われた 口腔内健診､
麟蝕活
動性試験カ リオスタシ トな らびにアンケー ト調査の縛果か ら小児期の癖蝕予防の要
点を解析 し､さらに2.
5
歳児の口腔内か ら分離 され るS.
mut
a
DS
､S
.
s
o
b
rl
'
Du
Sの存在 と
口腔内の状態の関係 をd
f歯数 と嚇蝕活性度によって評価 したものであ り､
次のよう
な結論を得たo
1
)1
.
5
歳時の (
Lo
wri
s
k:カ リオスタッ トスコア一､Ⅰ
.5以下 とHi
g
hri
s
k:カ リオス
タッ トスコア一､2.
0)スコア-をもとに被験者が2.
5歳な らびに3.
5歳児になった時
のdf歯数 と比較 した ところ両年齢時の平均d
f歯数は有意 にHi
g
hri
s
k児のそれが多
かった.さらに畠.
5
歳時のカ リオスタッ トスコア-をもとに分析す ると3.
5
歳時にお
けるd
f歯数で同様の結果を得た｡
2) 嚇蝕活性度に有意に関与するライフスタイルは､
噛み与え､
養育者,
授乳の継続､
仕上げ磨き､
間食の回数 と遊びなが ら間食を食べ る､
近所か らお菓子 をもらうなどで
あった｡
3
)1
.5
歳時 と2歳時の生活スタイルは､それ以降の年齢の嚇蝕活動性 にも影響を与え
た｡
4
)Lo
wri
s
kに比べHi
h ri
g
s
kg
roupでは､S
.
s
o
b
Fl
'
Du
SあるいはS
.
mut
a
DSとS
.
s
o
b
Tl
'
nu
s
が同時に高い確率で検出され､df歯数 も大であった｡これ らの知見は､
小児の嚇蝕予
防に役立ち歯科保健指導にエ ビデ ンスを与えるものである｡
よって本論文は博士 (
歯学)の学位授与に値す ると判定 した｡