| Summary: | 碩士 === 高雄醫學大學 === 牙醫學研究所 === 97 === Background:
The main key factors for inducing caries are: cariogenic bacteria, sucrose, tooth hardness and time. Emphasize on good oral hygiene to hamper cariogenic bacterial growth has become great importance in preventing caries. Mutans Streptococci which is the main cariogenic bacteria for causing caries lesions. There are 7 species in the Mutans Streptococci which include: S. mutans、S. sobrinus、S. cricetus、S. rattus、S. downei、 S. macacae and S. ferus. No study regarding cariogenic bacteria is available so far for Taiwanese children. Therefore this research is targeted on the soft dentin in the primary carious teeth from children aged 3 to 5 in Taiwan.
Methods:
Soft dentin in 35 primary molar from 35 children aged 3 to 5 were collected. Four selective media (MSB, TSY20B, GSTB and MSKB) were chosen to analyze the distribution and to distinguish the colonial morphology of Mutans Streptococci.
Results:
S. mutans is found in 32 out of 35 specimens; S. downei and S. macacae presented in three specimens and S. sobrinus and S. cricetus existed in one specimen. Media of MSB and GSTB have higher differential ability in distinguishing colonial morphology between species. Within the 35 specimen, 82.86% of pure colonies were identified as S. mutans. Only one specimen (2.86%) harbored both S. mutans and S. sobrinus. Bacteria found in saliva and plaques are not necessarily in representing the bacteria that induce caries, it simply proof that they are existing in the oral cavity. In this study, the samples were originating from the soft dentin with carious that can yield more accurate information in searching for cariogenic species.
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