Influence of different mixing pads on physical and mechanical properties of glass ionomer cement / 北京大学学报(医学版)

OBJECTIVE@#To analyze the influence of different mixing pads on the physical and mechanical properties of glass ionomer cement.@*METHODS@#Three different glass ionomer base cements were mixed with a plastic spatula on three different mixing pads including paper pad, glass pad and silicon pad whose HS were 40, 60 and 80. The GIC was packed into stainless steel molds to get specimens. Surface roughness, surface hardness and compressive strength were evaluated.@*RESULTS@#As for compressive strength, CF: There was the highest mean compressive strength that was significantly higher than those of silicon pad 60 group, paper 60 group and paper 20 group in silicon pad 40 group, the differences P values were 0.002, 0.027, and 0.036, statistically significant difference between the above groups (P<0.05). IX: there was the highest mean compressive strength that was significantly higher than those of silicon pad 60 group in paper pad 20 group,the differences P value was 0.008, statistically significant (P<0.05). FX: there was the highest mean compressive strength that was no significantly higher than those of paper pad 20 group in silicon pad 40 group, but was significantly higher than those of the other groups. As for surface hardness, CF: there was the highest mean surface hardness that was significantly higher than those of silicon pad 60 and 80 group, paper 60 group in silicon pad 40 group, the differences P value was 0.021, 0.001, 0.032, 0.008 and 0.016, statistically significant difference between the above groups (P<0.05). IX and FX: there was no statistical significance between any two groups in surface hardness. As for surface roughness, CF: there was no statistical significance between any two groups in surface roughness. IX: there was the lowest mean surface roughness that was significantly lower than those of paper pad 40 and 60 group in glass pad group, the differences P values were 0.003 and 0.027, statistically significant difference between the above groups (P<0.05). FX: there was the lowest mean surface roughness that was significantly lower than those of paper pad 60 group in glass pad group, the differences P value was 0.018, showing a statistical difference (P<0.05).@*CONCLUSION@#Mixing glass ionomer cement on silicon pad 40 results in higher compressive strength and lower surface roughness, worthy of clinical popularization.

Effects of different beverages on plaque pH of different caries-sensitive children / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To compare the impacts of different beverages on plaque pH of caries-sensitive and caries-free children and to evaluate the applicability of in situ pH measurements in human dental plaque using Beetrode microelectrode.</p><p><b>METHODS</b>The subjective population consisted of 20 children (aged 3-5 years). Ten of them were caries-free(dmft = 0); the other were caries-active (dmft > 4). The dental plaque pH were measured in situ with a pH microelectrode within 1 h after drinking three different beverages respectively. Then the resting pH value (pHrest), minimum pH value (pHmin), the range of the pH (deltapH) was analyzed by ANOVA. Results There was a significant difference in pHrest between caries-free and caries-sensitive children. All the pH responses in the plaque following drinking three different beverages showed a classic Stephan-type response. The differences of the pHmin, deltapH in sound sites were no statistic significance (P > 0.05) after drinking beverages in caries-free children. However the changes in the caries-sensitive group were more pronounced than the non-caries group. There were significant differences on the pHmin, deltapH among different beverages (P < 0.05).</p><p><b>CONCLUSION</b>The cariogenicity of plaque in caries-active children was stronger than that of the caries-free group. Different beverages have different potential cariogenicity.</p>

Study on the horizontal transmission of oral Streptococcus mutans in day-nursery children / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To analyze genotypic diversity of oral Streptococcus mutans (S. mutans) and find out horizontal transmission possibility of the microbe in day-nursery children.</p><p><b>METHODS</b>The plaque samples were scratched with sterilized toothpicks from teeth of 32 day-nursery children aged between 3 and 4, then cultured on MSB plates. Clones with representative S. mutans-like were subcultured and identified to species level biochemically. AP-PCR fingerprinting was performed to distinguish genotypic diversity of those isolates. Then S. mutans isolated from different children with very similar amplicon profiles were examined by chromosomal DNA fingerprinting analysis.</p><p><b>RESULTS</b>S. mutans were isolated in oral cavities of 78.1% children, 100% in caries and 69.6% in caries-free children. A total of 57 genotypes were identified by AP-PCR. More than one amplitypes were identified in 88% of the 25 children with S. mutans colonization. Two pair of children shared common genotypic S. mutans.</p><p><b>CONCLUSION</b>There is no evident relation between number of genotype detected and caries. The presence of matching genotypes of S. mutans among day-nursery children suggests the horizontal transmission may exist.</p>

Transmission way of oral Streptococcus mutans in children / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To find out different transmission ways of oral mutans Streptococci (MS) in nursery children.</p><p><b>METHODS</b>The study group included 44 nursery children between 3 and 4 years of age and 20 mothers. Dental plaque samples were collected with sterile toothpick and cultured on MSB plates for 48 h. Individual MS colonies representative of the colonial morphologies were subcultured on TPY plates. These strains were biochemically identified to species level. AP-PCR fingerprinting analysis was preformed after identification.</p><p><b>RESULTS</b>MS was isolated in oral cavities of 65.9% children in 44 babies and 50% pairs in 20 mother-child pairs. A total of 98 MS isolates from 44 children and 20 mothers were isolated. Thirty-two different amplitype were identified in 10 mother-child pairs colonized by MS and there were similar genotypes in 7 pairs of mother-child. Twenty-nine different amplitype were identified in 24 nursery children, and there were 2 genotypes of MS isolated repeatedly among 13 nursery children.</p><p><b>CONCLUSIONS</b>The presence of matching genotypes of MS among nursery children and their mothers suggests horizontal and vertical transmission.</p>

Study on the horizontal transmission of oral Streptococcus mutans in children / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To find out horizontal transmission of oral Streptococcus mutas (S. mutans) in nursery children through analyzing the similarity of S. mutans genotypes.</p><p><b>METHODS</b>The study group included 24 nursery children between 3 and 4 years of age. Dental plaque samples were collected with sterile toothpick and cultured on MSB plates for 48 h. Individual Streptococcus mutans group colonies representative of the colonial morphologies were subcultured on TPY plates. These strains were identified to species level biochemically. AP-PCR fingerprinting was preformed after identification. S. mutans isolates from different children with very similar fingerprinting profiles were examined by chromosomal DNA fingerprinting analysis.</p><p><b>RESULTS</b>Streptococcus mutans group were isolated in oral cavities of 66.7% children, 58.3% in caries-free and 75.0% in caries children. A total of 4' S. mutans isolates from 24 subjects were analyzed by AP-PCR, and 29 different amplitypes were identifyied, 45.8% carried tw. genotypes. There were 2 genotypes of S. mutans isolated repeatedly among 12 nursery children.</p><p><b>CONCLUSION</b>The presence of matching genotypes of S. mutans among nursery children suggests horizontal transmission.</p>