Cloning and expression of Streptococcus salivarius urease gene in Escherichia coli / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To clone Streptococcus salivarius (Ss) 57. I urease gene, which can express ureolytic activity in Escherichia coli (Ec) without adding extra nickel ions.</p><p><b>METHODS</b>Urease gene was cloned by polymerase chain reaction in three separate parts. The three separate plasmids were digested by specific restriction enzymes and ligated together. The expression of the complete urease gene in Ec was detected by phenol red assay and pH analysis.</p><p><b>RESULTS</b>Urease gene of Ss 57.I was eventually cloned and proved correct. Urease activity of the obtained clone was positive in Ec. Without adding extra NiCl(2), the recombinant Ec could hydrolyze urea to produce ammonia, resulting in the increase of pH value.</p><p><b>CONCLUSIONS</b>The clone of Ss urease gene obtained in this study could express ureolytic activity in Ec without adding extra nickel ions. The current clone can be used to construct ureolytic effector strain used in replacement therapy in caries prevention.</p>

A national survey on dentin hypersensitivity in Chinese urban adults / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the prevalence of dentin hypersensitivity in Chinese urban adults aged between 20 - 69 years old and the factors related to dentin hypersensitivity.</p><p><b>METHODS</b>The Chinese national survey on dentin hypersensitivity was conducted in 20 - 69 years old adults in six representative cities, Beijing, Shanghai, Guangzhou, Wuhan, Chengdu, and Xi'an in 2008. A multi-stage stratified randomizing sampling method was used. Subjects were recruited from 36 urban survey sites in 6 cities. A structured questionnaire and a clinical examination on dentin hypersensitivity were used in the survey. The dentin hypersensitivity was diagnosed by a subject self-perceived short, sharp pain in response to a blast of cold air from a triple syringe administered to a tooth surface in 1 cm.</p><p><b>RESULTS</b>In total, 7939 twenty to sixty-nine years old subjects completed a structured interview and underwent a clinical examination on dentin hypersensitivity. Among them, 40.7% (3230/7939) of the subjects reported being suffered from teeth sensitivity. When confirmed using a blast of air from a triple syringe and by ruling out other causes of sensitivity, such as caries, the prevalence was 29.7% (2354/7939), and the mean number of sensitive teeth was 1.4. The highest prevalence of dentin hypersensitivity [39.1% (622/1592)] was found in 50 - 59 years old group. The commonest teeth affected were the premolar teeth and the commonest initiating factor was cold drinks. Female, low education level, with gingival recession, attachment loss, and with the history of acidic substances derived from the stomach was related to dentin hypersensitivity.</p><p><b>CONCLUSIONS</b>Dentin hypersensitivity was common in 20 - 69 years old Chinese urban adults. Dental professionals should give further emphasis to it.</p>

Therapeutic effects of fenestration in treatment of dentigerous cyst in mixed dentition stage / 上海第二医科大学学报

Objective To observe the therapeutic effects of fenestration in the treatment of dentigerous cyst in mixed dentition stage. Methods From 2004 to 2007, 8 cases of dentigerous cyst in mixed dentition stage were treated, among whom 3 were boys and 5 were girls with ages between 7 and 12 years old. The dentigerous cysts of 2 cases were in superior maxillary bone and the other 6 cases were in inferior maxillary bone. Each of 5 cases had one tooth in dentigerous cyst cavity, and each of the other 3 had 3 teeth in dentigerous cyst cavity. All patients received fenestration under local anesthesia. The patients were followed up for 18 months after fenestration, and the soft tissue healing, facial malformation, permanent teeth eruption and bone tissue healing were observed. Results It was found during follow up that cyst cavity disappeared in all the patients and all had normal facial morphology with no maxillary bone malformation. In five cases, permanent teeth erupted totally and dental occlusion kept normal. In one case, 2/3 of permanent teeth erupted and dental occlusion kept almost normal. While in the other two cases, permanent teeth were to erupt. It was revealed by X ray examinations that the shadow of maxillary bone density decrease disappeared in all the patients. Conclusion Fenestration can keep the teeth and bone in the treatment of dentigerous cyst in the mixed dentition stage.