Jpn. J. Infect. Dis., 53, 2000

Laboratory and Epidemiology Communications

New Dental Drug Delivery System for Removlng Mutans Streptococci
from the Oral Cavlty: Effect on Oral Microbial Flora
Hiroaki Takeuchil, Hidenobu Senpukul, Khairul Matinl, NoboruKanekol,
Noriko Yusal, Eiji Yoshikawa2, Hirohisa Ida2, susumu Imail , Tosiki Nisizawal,
Yasuhito Abeil, YoshiharuKono3, Takuji Ikemi3, Yoshihiro Toyoshima4,
Kazuo Fukushimal,5 and Nobuhiro Hanadal *JDepartment of Oral Science, National Institute of lnfectious Diseases,Tob/0 1 62‑8640,2B肱Co. Ltd., Too,0 151‑0051,

3Department of Operative Dentistyy, Nihon Un iversiOJ School ofDentistyy al Matsudo,
Chiba 271‑8587,

4Dai‑ichi Mutual Life Insurance Company Hibiya Medical Center

Tob,0 100‑8411 and5Department ofMicTlDbiology, Nihon UniversitySchool ofDentistyy at Matsudo,
Chiba 271‑8587
Communicated by Nobuhiro Hanada(Accepted November 2, 2000)

Dental caries is caused by mixed infection of pathogenic

indigenous microbiota and biofilmformadon ( 1 ). Streptococczm

subjects (A, B, C, and F, see below) showed no identifiablerecolonization by S･ mutans onthe tooth surface 60 days aRer

mutans produces biofilm on the tooth surface, leading to thethe end of the treatment.

development of dental caries. Various approaches have been

The effect of the treatment on the oral nora was examineddeveloped for removlng S. mutans from the oral cavlty ln

as its perturbation may have adverse effects. Plaque andorder to prevent dental caries (2‑5). TYle Present Study examinedsaliva samples were taken before the trialand at I, 24, and 60

effect of a dental drug delivery system (3DS) using 0.2%

days aRer the treatment. Plaque samples were collected fromchlorhexidine (CHX) on S. mutans and other oral bacterialnora.
The 3DS consists of individual trays, called Drug Retainer,

the upper right second premolar and first molar teeth byrubbing witha cotton swab postero‑anteriorly alongthe buccal

that丘t onto and deliver small amount of anti‑bacterial dmgs

transport medium (0.4% agar, 0. I 5% thioglycolate/phosphatesurface. The samples were transferred into 1 ml of reducedbuffered saline) in sterile tubes (SEEDSWAB No. 1 , Eiken(in high con.centration) to the tooth surfaces･ This system iseasy to manlpulate and keeps the dmgs in direct contact with

Chemical Co., LTD., Tokyo). At the same time, saliva

the tooth surface without being diluted by saliva so that thesecreted over a period of 3 min, while being stimulated bybacteria on the tooth surface, but not on the oral mucosa, arebiting paramn gum, was collected into ice‑chilled sterile

killed･ The anti‑microbial drug used was CHX which is widelybottles. The sample was then transferred by using a COttOn

accepted as an effective antiseptic in dentistry (5). Before
application of 3DS, dental biofilms which prevent theswab into the transport medium and 4 ml of Brain HeartInfusion (BHI) broth. The BHI broth containing the plaquepenetration of anti‑microbial agents (6) were.removed byor saliva samples was sonicated by ultrasonic dispersion (60means of Professional Mechanical Tooth Cleanlng (PMTC).

W power output) for 10 seconds, and poured onto blood agar

The 3DS was applied for 5 min twice a day (moming andplates or Mitis‑Salivarius agar plates containlng 0.02 Mbacitracin(MSB), respectively, in a volume of 50 Lil by usingaftemoon). In addition, the oral cavitywas rinsed with 10

an EDDY JET spiral system (Gunze Sangyo, Inc., Tbkyo).
After anaerobic culture for 48 h, total bacterial colonies on
the blood agar and total Streptococci colonies on the MSB

ml of O･2% CHX gluconateヮouthwash (Corsodyl; ICI,Maccksfield, England) for 1 mln after lunch every day. The
廿eatment was continued fわr 9 days.

Seven healthy human volunteers having S. mutans on theplates were counted. S. mutans could be identified by their

tooth surface partlCIPated in the study. Among them fourcharacteristic appearance.

The number of colonies of total Streptococci before the*ComSpOnding author: Fax: +8 1‑3‑5285‑1 172, E‑mail: nhanada

treatment in all the subjects ranged from lO6･5 to 108 cfuml@nih.gojp(Fig. lA) in the plaque samples. A鮎r the PMTC and 3DS211

Jpn. J. Infect. Dis., 53, 2000.".A:., dnh.. ･1..,..

treatment, the total Streptococci decreased to less than 1 06･5

completely in 60 days (Fig. lA). Similar curves were obtainedCfu/ml in 1 day, but recovered at least partially in 24 days andfor the total bacteria (Fig. 1B). The effect on Streptococci(Fig. lC) or onthe total bacteria (Fig. lD) in the saliva samples

was minimal.

In conclusion, the 3DS in combination with PMTC which

selectively killed S. mutans on the tooth surface is consideredsafe in that the oral Dora ismimimally perturbed.
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Bacterial biofilms: a common cause of persistent infec‑

The data on subject G was omitted due to a technicalfailure.

tions. Science, 284, 13 18‑1322.

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