Molecular Biological Study of Initial Acquisition of Mutans Streptococci in Children's Mouths

Research Project

Project/Area Number	09672108
Research Category	Grant-in-Aid for Scientific Research (C)
Allocation Type	Single-year Grants
Section	一般
Research Field	矯正・小児・社会系歯学
Research Institution	HIROSHIMA UNIVERSITY
Principal Investigator	KOZAI Katsuyuki HIROSHIMA UNIVERSITY DENTAL HOSPITAL ASSISTANT PROFESSOR, 歯学部・附属病院, 講師 (10178212)
Project Period (FY)	1997 – 1998
Project Status	Completed (Fiscal Year 1998)
Budget Amount *help	¥3,100,000 (Direct Cost: ¥3,100,000) Fiscal Year 1998: ¥1,000,000 (Direct Cost: ¥1,000,000) Fiscal Year 1997: ¥2,100,000 (Direct Cost: ¥2,100,000)
Keywords	MUTANS STREPTOCOCCI / TRANSMISSION / DNA FINGERPRINTING / INITIAL ACOUISITION / DENTAL CARIES / 家族内伝播 / 乳幼児 / 歯牙萌出 / 菌定着
Research Abstract	The aims of this study are to find out the initial acquisition of mutans streptococci (MS) in chilren's oral mouths and the source of infection and to observe intrafamilial distribution longitudinaly. Twenty of the 35 children initially acquired MS at a median age of 24.5 months. The rest of the samples remained free from MS mainly the children with primary teeth have not erupted yet. The colonies count showed numbers of colonies in each child increase from time to time. MS acquision is sooner in child has not spaced dentitional arch (ave. 1y7m) than in child has not spaced dentitional arch (2y3m). DNA fingerprinting result showed that mother is not considered to be the main source of infection, some children appeared to acquire mutans from someone else. In longitudinal study of intrafamilial MS distribution for three families, MS strains were variable among 4 years and new strains were derived chiefly from familiy members.