เชื้อแลคโตบาซิลลัสกับโรคฟันผุในเด็ก

Thesis (Ph.D., Oral Health Sciences)--Prince of Songkla University, 201

Stress distributions in rubber butt-joints bonding

The objective of this research is to investigate the effect of shear modulus of thin adhesive layer on stress distributions and deformations in rubber butt-joints with Finite Element Method (FEM) and shape factor. The research methods comprise of three important tasks. First, the material properties of adhesive layer and rubber are figured out in order to use in 3-D FEM models of the rubber butt joint. Second, the FEM models are verified with experiments in order to evaluate the accuracy. Third, the effect of shear modulus of thin adhesive layer is studied from FEM models. The finding of this research indicates that the shear modulus of thin adhesive layer and shape factor of the rubber joint increases the resistance of lateral deformation and hydrostatic pressure in rubber butt-joints

Comparison between the efficacy of self-prepared chlorhexidine varnishes and of EC 40®

It was reported that clinical application of chlorhexidine (CHX) varnish could reduce dental caries occurrence effectively.However, this form of CHX is not commercially available in Thailand. Our previous study showed that the released CHX from 20% and 40% self-prepared CHX varnishes were sufficient to inhibit the growth of Streptococcus mutans. This study aimed to compare the efficacy of the 20% and 40% self-prepared CHX varnishes to commercial CHX varnish EC 40®. The study included CHX release, antibacterial activity against S. mutans ATCC 25175, and the cytotoxic effect of CHX on fibroblasts. The results showed that the greatest amount of CHX was released by EC 40® followed by 40% and 20% selfpreparedCHX, which were 4,111.29 g, 2,408.7 g, and 1,136.4 g, respectively. EC 40® gave the strongest antibacterial activity; however, there was no statistical significant difference. The 20% self-prepared CHX gave the highest viability of fibroblasts. This study indicates that the self-prepared CHX should be considered to be used as antimicrobial agents for the prevention of dental caries

Effect of Long-Term Consumption of Lactobacillus paracasei SD1 on Reducing Mutans streptococci and Caries Risk: A Randomized Placebo-Controlled Trial

Background: A previous study revealed Lactobacillus paracasei SD1, a probiotic strain, could reduce mutans streptococci (MS). The aim of this study was to evaluate the long-term effects of L. paracasei SD1 on the colonization of MS, and whether caries lesions developed. Methods: After informed consent, 122 children were recruited and randomly assigned to the probiotic or control groups. The probiotic group received milk-powder containing L. paracasei SD1 and the control group received standard milk-powder once daily for six months. Salivary MS and lactobacilli were enumerated using differential culture at baseline and at three-month intervals for 12 months. The persistence of L. paracasei SD1 was investigated using AP-PCR for DNA-fingerprinting. Oral health was examined at baseline and at the end of the study according to WHO criteria. Results: The long-term consumption could prolong colonization of L. paracasei SD1. Significantly reduced MS counts and increased lactobacilli levels were found among children in the probiotic group. There were less caries lesions in the probiotic group at the end of the study. A significant reduction of the development of new caries lesions (4.5 times) was observed in the high caries risk group but not in the low caries risk group. Conclusions: Results demonstrate that the long-term daily ingestion of the human-derived probiotic L. paracasei SD1 significantly reduces the number of MS and caries risk in the high caries group