The purpose of this study was to investigate the expression of transforming growth factor-

目的　探索一种快速、简便地从人类唾液中同时检测变形链球菌和远缘链球菌的方法。方法　分别以变形链球菌gtfI和远缘链球菌gtfB基因设计两组成套引物,首先用套式PCR(二次PCR)检测变形链球菌和远缘链球菌标准株和临床株,然后用套式PCR 直接从唾液中检测这两种细菌。结果　变链菌(血清型c,e,f) 的标准株及临床株第1 次PCR 扩增产物为517 bp, 第2 次扩增产物为468bp;远缘链球菌(血清型d,g) 及道勒链球菌(血清型h)的标准株及临床株第1次PCR 扩增产物为712bp, 第2次扩增产物为663bp;其他异种菌均不能扩增出产物, 因此该PCR 检测具有高度的特异性。细菌纯培养物及唾液PCR 检测的敏感性分别是: 第1 次PCR 为105CFU, 第2次PCR 为103CFU。结论　套式PCR能快速在人类唾液中同时检测变形链球菌和远缘链球菌。该检测方法有望运用于临床检测,对揭示两种细菌与龋病发生关系的研究具有一定价值。

The aim of this study was to clarify the genotypic stability of mutans streptococci (MS) longitudinally during orthodontic treatment. Plaque samples were obtained from the supragingival smooth surface of the upper right teeth at four stages: prior to and after 1, 3 and 6 months of orthodontic treatment. Levels of total viable count, total streptococci and MS in dental plaque of 17 patients were recorded. Streptococci isolated from dental plaque samples were identified as MS on the basis of their morphological and biochemical properties. DNA was prepared from 713 strains of MS and the strains were then identified with polymerase chain reaction (PCR) again. Arbitrarily primed PCR (AP-PCR) fingerprinting was applied in determining the genotypes of MS. The results indicated that levels of total viable count, total streptococci and MS increased significantly after the fixed appliances were bonded. A maximum of 3 different genotypes were found in an individual. All the genotypes were found again after the application of the fixed appliances in 17 patients. A new AP-PCR typing pattern was found after the application of fixed appliances for 1 month in patient 1. That strain was not detected either prior to or after 3, or 6 months of treatment. The result indicated that the MS clones were very stable during orthodontic treatment.

The purpose of this study was to investigate whether there was transmission between adults in Chinese families using chromosomal DNA fingerprinting. Plaque samples were obtained from buccal and occlusal surfaces of 11 married couples. The colonization levels of mutans streptococci were estimated as colony-forming units per milliliter, and caries experience was scored by decayed, missing and filled teeth. Information about medical history, diet regimes and age at marriage was obtained. The isolates were serotyped by biochemical test and genotyped using the restriction endonuclease HaeIII. The procedure was repeated after 3 months. The results showed that 1 couple had the same genotype of mutans streptococcus at the first examination, but this could not be repeated for the husband who had lost his mutans streptococci at the second examination. On the contrary, another couple that did not have the same mutans streptococcal genotype at the beginning had the same genotype after 3 months. No matching of genotypes was observed within 8 couples. In 1 male, no mutans streptococci were detected, therefore that couple was not considered. These data indicate that spouses had a chance to be infected by strains of mutans streptococci from another person. The results suggest that there may be transmission between adults in Chinese families, but it may be difficult for mutans streptococci to colonize another mouth permanently.

To study and evaluate root canal preparation using greater taper(GT) hand files in curved root canals. Material and Methods: Twenty-three teech with 39 curved root canals in outpatients were instrumented with GT hand files, using the balance force technique, and obturated with standard gutta-percha points and a sealer(AHphus) using the lateral condensation method. Radiographs taken before, during and after the operation were used to evaluate the efficiency of preparation and obturation. Results: In all cases the master apical GT hand file followed the course of the canal so that a continuously tapered root canal shape was achieved. No apical blockage or obvious aberrations were found. Only one file fractured during instrumentation. The mean preparation time for each curved canal was 9.75