Jpn. J. Infect. Dis., 54, 2001

Laboratory and Epidemiology Communications
Mutans Streptococci and Lactobacillus as Risk Factors f♭r

Dental Caries in 1 2‑Year‑Old Children
Yoshiaki Nomura, Hidenobu Senpuku, Nobuhiro Hanada* and Takashi KumagaiI
Department ofOral Science, National Institute of Infectious Diseases,

Toyama 1‑23‑1, Shinjuku‑ku, Too,0 162‑8640 andlHiyoshi‑Dental Clinic,

Hiyoshi‑chyo 2‑1‑16, Sakata‑shi, Yamagata 998‑0037
Communicated by Nobuhiro Hanada(Accepted April 6, 2001)

諾eesp:aetZcLhOgaCenOTfc:bS:cfTLun:a;cTnhS t:hSae'so?:ul:a:andVSZty;n.C器ria:;g:dbeiannCh:lzui;'e:sHEitgl:csaSflnuyddsiTeeSvEs'a2.1f'S‑芸70vncatffosmTombr:eineose望hdCe:i:nc:tlr.ii:tccu;lguefsSi,?:V;?
However, as these studies have been carried out based on
medical checkups, professional interventions have not been*Co汀eSpOnding author: Fax: +81 ‑3‑5285‑1 1 72, E‑mail: nhanada@nih.go.jp

evaluated.

43

Jpn. J. Infect. Dis., 54, 2001

The World Health Orgapization (WHO) has recommended

3･92 decayed or filled teeth per person･ The mean follow‑up

a suⅣey at age 12 as an lntemational standard because, atperiod was 3.97 ± 2.29 years.

this age, all pemanent teeth have empted, except f♭r the third

Salivary S. mutans and Lactobacillus were counted bymolars (5)･ WHO is now seeking to reduce the number ofuslng a commercially available S. mutans and Lactobacillus

decayed, missing orfilled teeth (DMF) in 1 2‑year‑old children

evaluation kit, Dentocult‑SM and Dentocult‑LB (Orionto less than three. The purpose of this study was to assess theDiagnostica Co. Ltd., Epsom, Finland). The dental states wereassociation between the incidence of dental caries and levels

classed according to the manufacturer's instructions, i.e., forof salivary S･ mutans and Lactobacillus in patients receiving

S. mutans, Dentcult SM Class 0‑1 : <100,000 colony forming

professional preventive care.

units (CFU) S. mutans/ml saliva; Class 2 loo,000 <CFU/ml

A total of2,132 under the age of20 visiting pnvate dental<1,000,000; and Class 3 >1,000,000 CFU/ml, and fわr Lacto‑clinics for professional preventive programs were consideredexamined for dental caries and salivary S. mutans and Lacto‑

bacillus, Dentcult‑LB Class 0 <1 ,000 CFU Lactobacillus /ml
in saliva; Class 1, 1,000 <CFU/ml <10,000 CFU; Class 2,10,000 <CFU/ml <100,000; and Class 3 100,000 <CFU/ml

bacillus in the baseline study, and those 12 years of age were

<1 ,000,000.

in the present study･ Of these patients, 187 patients wereanalyzed in this study. The study population consisted of 80

Data for dental caries and dental plaque conditions, salivary(43･0%) males and 107 (57.0%) females averaging 5.53 ±buffering capacity, and 5 1min stimulated salivary volume wereTable 1. Crude and adjusted odds ratios forthe incidence of dental caries
CrudeOdds

ratio

Follow up periods

0.83 1Adjusted
95%CI

0.725‑0.953

P

value

0 0 0 0 0 0 3 5 0 0 OO 5 0 0Odds

ratio

95%

CI

P

value

0 2 5 tJ ′nV

Sex

1,308

0.716‑2.389

df

1.024

0.946‑1.110

S. mutans

1.637

1.187‑2.258

I.160‑2.255

Lactobacillus

I.63

1.148‑2.314

1.153‑2.360

Salivary buffering′LU 1 Qノ 0capacity

1 1 1 1 5 0 5 tJ 8 7 1 5L o o o 0 7 8 002 1 5 45 0 4 01JIl

2 1 2 2 4 5 7 ｣ 5 8 2 73 07 9 つJ0000 O7｣2tJ つJ AV 0 0 0 2 tJ
111 1

0ノ 5 2 ∠U′0 0 0 15044

1.026‑2.483

Saliva volume0.705‑I.587

Dental plaque0.787‑2.591

Diet

0.902‑2.366

0 0 0 0 0 7 2 .1

つJ O 4 28 ′0 2 3

F luorideappl ication

1.881

1.261‑2.805

0.002

1.716

1.140‑2.582

0.01Fouow‑up periods were considered to be potential confounders and were adjusted by multiple logistic models.
TYle Wald test was used to circulate P values.

Table 2. Dose‑response relationships between the incidence ofdentalcaries andassociation with血e events

FactorCriteria

Odds

ratio

95%

CI

S. mutans

Class 0

CFU<104

Class 1

CFU<1 05l.669

0.439‑6.346

Class 2105<cFU< I 06

3.332

1.158‑9.539

Class 3

1 06<cFU

4. 1791.447‑12.069

Reference Group

Reference GroupLac tobac i1 lu島

Class 0

CFU< 103Class I

1 03<CFU< 104l.0000.399̲2.506

Class 2

1 04<CFU< 1 05

3.806

1,391‑10.415

Class 3

1 05<CFU<106

3.581

0.914̲14.029

Class 07.0<pH in saliva

Reference GroupClass 15.5<pH<7.0l.001

0̲I ,0008

Class 24.5<pH<5.5

1.800

1.186̲12.49

CIass 3pH<4. 58.940

2.90‑27.57

Reference Group

Buffering capacity

Fluodde application

Class 0Home, Professional

Class 1Homel.894

Class 2

Profcssional

2.927

0.982̲8.726

Class 3

Nonc

4.689

0.805‑27.329

0.783‑4.581

Home: Brushing using nuoride dentifrice was performed every day at morning andnigtlt at home.

Professional: Topical nuoridc application was performed in dental clinic one time

every 3 months.

44Jpn. J. Infect. Dis., 54, 2001
Obtained by regular dental checkups. The salivary buffering

micro‑nora (6). In this study, we confirmed the contribution

capaclty Was evaluated by the commercially available kit

offluoride‑application and salivary‑buffering‑capacity

Dent‑BuffStrips (Orion Diagnostica). The fluoride usage andfactors to the host. Fluoride application has been known tothe times or血ily fわod intake were detemined uslng queStion‑reduce the incidence of dental caries by changlng hydroxy
apatite tofluoroapatite on the tooth surface and by preventlng

nalreS.

Befbre the analysts, patients were divided into two groups:

the attachment of S. mutans to the tooth surface. Professional

patients free from dental caries and patients who had at least
one decayed or filled tooth. The cross table and chi‑squarepreventive programs were fわund to reduce the prevalence ofdental caries･ However, even for patients participatlng ln

test were used to check the correlation between the factors

professional programs, salivary S. mutans and Lactobacillus

investlgated in this study. Only two factors, S. mutans andLactobacillus, wpre correlated (data not shown)･ Logistic

remain as strongrisk factors for dental caries. Controllingthesefactors will thus lead to one powerful strategy for preventlng

regression analysis Was used to evaluate the crude or adjusted

dental caries.

odds ratios and their associated 95% confidence intervals (CI).
The follow‑up periods were treated as potential confounders.

REFERENCES

Table 1 shows the crude and follow‑up periods adjusted byThe levels of salivary S. mutans and Lactobacilluswere found

1. Loesche, W. J. (1986): Role of Streptococcus mutans inhuman dental decay. Microbiol. Rev., 50, 353‑80.

to be closely related to the incidence of dental caries. Salivary

2･ Hanada, N. (2000): Cumnt understanding of the cause

the odds ratios for the incidence ofdental caries at age 12.

buffering capacityand nuoride qpplication were also correlated

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with the incidence ofdental canes･ The levels of dental plaque

3. Llena‑Puy, M. C., Montanana‑Llorens, C. and Fomer‑

were not statistically slgnificant but were highly correlated

Navarro, L. (2000): Cariogenic oralflOra and its relation

with the levels ofS. mutans and Lactobacillus at the baseline.

to dental caries. ASDC. ∫. Dent. Child., 67, 42‑69.

Dose‑response relationships were explored to determine
factors associated with the incidence of dental caries. As

4･ Retlman, J. (2000): Trends in preventive care: cariesrisk

shown in Table 2, Obvious dose‑response relationships wereAssoc., 131, 8‑12.
5･ World Health Organization (1997): Oral Health Surveys,Basic Methods. 4th ed. World HealthOrganization, Geneva.

assessment and indications for sealants. J. Am. Dent.

found between dental caries and each of the factors, the levelsof S･ mutansand Lactobacillus, buffering activity, mdfluoride

6. Keyes, P. H. (1969): Presentandfuture measures for dental
caries control. J. Am. Dent. Assoc" 79, 1395‑1404.

application.
The course of the dental caries was fわund to be multi‑

factorial, with three prlmary factors: host, substrate, and45