大鼠牙髓细胞的分离培养及超微结构观察

目的 探讨牙髓细胞的培养方法和生长状况,观察其形态结构特征,为进一步研究牙齿的发育提供实验基础.方法 采用胶原酶消化分离的方法分离大鼠的牙髓细胞并在DMEM培养液中培养,运用透射和扫描电镜技术观察细胞的形态结构特征.结果 培养的牙髓细胞呈梭形,细胞生长状况良好,细胞器发育正常,并且有细胞增殖和分裂能力.结论 利用酶消化分离的方法分离培养的牙髓细胞,能够保持其生活状态及增殖分裂能力.     

Substance P stimulates release of RANKL via COX-2 expression in human dental pulp cells

Objective: Our previous study found that substance P (SP), a sensory neuropeptide, was expressed in the dental pulp of rats during experimental tooth movement. We examined the effects of SP on the production of prostaglandin (PG) E₂ and the receptor activator of nuclear factor- B ligand (RANKL) by human dental pulp fi broblast-like (HDPF) cells. Materials and methods: SP was added to cultured HDPF cells at concentrations ranging from of 10⁻⁴ to 10⁻¹² mol/L. PGE₂ and soluble RANKL (sRANKL) levels were determined using enzyme-linked immunosorbent assay kits. Gene expression was confi rmed by RT-PCR analysis. Pit formation assays using dentin slices were carried out to examine the effect of SP on osteoclastogenesis. Results: The levels of PGE₂ and sRANKL increased in the presence of SP, though the increases were greater in the experimental groups in both a time- and concentration-dependent manner, and the increase of RANKL was partially mediated by PGE₂ . The gene expression of cyclooxygenase (COX)-2 and RANKL was up-regulated, and conditioned medium samples obtained from HDPF cells treated with SP induced bone resorption. Conclusions: SP stimulated the production of PGE₂ and RANKL, and promoted bone resorption. Therefore, SP may be involved in pulpal inflammation and root resorption during orthodontic tooth movement. Received 11 April 2005; returned for revision 27 July 2005; returned for final revision 20 September 2005; accepted by M. Katori 2 November 2005     

Coping with dental treatment: The potential impact of situational demands

Coping strategies and anxiety responding of dental patients were studied in order to test the generalizability of previous findings based on volunteer blood donors. State and trait coping measures were administered once, and a process coping scale was administered at three points throughout treatment. Self-report, behavioral observation, and psychophysiological measures of anxiety were sampled for the same periods as process coping. Findings included the replication of a negative relationship between avoidant coping and patient anxiety ratings. Fluctuations in coping were evident across periods, and impact of situational demands and constraints was introduced as an explanation for these variations. A method for direct assessment of coping consistency was introduced. On the basis of the replicable associations with anxiety measures, the ability to detect changes in coping within a situation, and the ability to provide direct evidence of coping consistency, the use of process methodology for coping assessment is encouraged.This research was conducted while the first author was supported by funding from the Medical Research Council of Canada.Portions of this research were presented at the annual convention of the Society of Behavioral Medicine, Philadelphia, 1984.     

Stress and dental caries in the rat

The stress of crowding and exposure to inescapable electric shock increased both the incidence and the severity of dental caries in rats housed in a conventional animal facility. Male Osborne-Mendel rats were inoculated intraorally with cariogenic bacteria, fed a high-sucrose diet, and housed in either a conventional or a sheltered facility. Rats in both housing conditions were subdivided into control and stress groups. At the end of the 56-day trial period, stressed rats from conventional housing had a significant increase in both incidence and severity of dental caries in comparison to their controls. In contrast, stressed rats from sheltered housing had a trend toward increased cariogenesis which reached significance in only one of five scores. These rats also failed to gain weight comparable to their controls, making it possible that stress-induced reduction in appetite partially offset stress-induced exacerbation in cariogenesis.This investigation was supported in part by the following Grants from the United States Public Health Service: CA 20093, HL 22727, and HL 07374.     

Mirror-image dental fusion and discordance in monozygotic twins

A pair of monozygotic twins had similar but not identical dental anomalies. One twin had fusion of deciduous mandibular lateral incisor and canine on the left, with normal dentition on the right; the co-twin had right mandibular incisor/canine fusion, with aplasia of the lateral incisor on the left. These findings are discussed in the context of the related phenomena of situs inversus, mirror-imaging in twins, and gradients of severity of anomalies in the four copies of the mandibular developmental dental field. © 1994 Wiley-Liss, Inc.     

Characteristics of employment and job satisfaction in nontraditional dental hygiene practice settings

Little is known concerning the employment characteristics of hygienists practicing in nontraditional settings. Respondents were identified through screening (n = 38,380) a listing of the entire population of hygienists licensed in the United States. The screening identified 1,301 hygienists practicing in nontraditional settings. These hygienists were mailed comprehensive questionnaires; completed questionnaires were returned by 84.3 percent of the hygienists. Data were collected describing hygienists' reasons for seeking employment in nontraditional settings, their sources of information concerning job opportunities in nontraditional settings, benefits, and job satisfaction. The main source of information concerning employment opportunities in nontraditional settings was "word of mouth." Hygienists were motivated to seek employment in nontraditional settings primarily by a desire for a more challenging position and personal satisfaction. The hygienists were overwhelmingly satisfied with all aspects of nontraditional employment except opportunities for advancement. Respondents were found to receive standard benefits similar to those of employees in other industries.     

Characterization and cross-reactivity of rabbit antisera to plaque toxins

The effects of heat labile, high molecular weight water-soluble toxins from bacterial plaque on HL60 promyelocytic cells were examined. On gel filtration, four inhibitors of HL60 cell growth and two inhibitors of HeLa cell growth (PT1, PT2) were detected. The first and third HL60 cell inhibitors corresponded to the two HeLa cell inhibitors. The last eluted HL60 cell inhibitor (plaque leukotoxin, PL) did not inhibit HeLa cell growth. Anti-PT2 antibodies reduced the activity of enriched PT2 by 20-50%, but all other antisera tested exhibited no effect. Anti-PL antibodies detected antigens from Actinobacillus actinomycetemcomitans, although anti-A. actinomycetemcomitans and anti-Capnocytophaga sputigena antibodies did not react with plaque extract. These findings suggest that the plaque toxins examined in this study were probably not derived from these two bacteria.     

Prevalence and distribution of gingivitis and dental caries in children aged 6–12 years in Brisbane primary schools

A study of caries experience and gingivitis prevalence in 6-, 9- and 12-yr-old children attending primary schools in Brisbane was undertaken in November/December 1983. Children from high socioeconomic level (SEL) schools exhibited lower dmft and DMFT scores at all ages. At age 6 yr the proportion of children with caries-free primary dentitions was for high SEL Schools 70%, for middle SEL schools 52% and for low SEL Schools 23%. At 12 yr DMFT scores were 1.8 (high), 2.1 (middle) and 3.3 (low). Similar differences in gingivitis prevalence occurred, children from high SEL schools displaying a much lower proportion of bleeding sites than those from middle and low SEL schools. For selection of children at "high risk" to gingival disease for intensive prevention programmes, an increased emphasis on probing techniques is indicated to achieve diagnostic consistency.     

Free Sugars Intake among Chinese Adolescents and Its Association with Dental Caries: A Cross-Sectional Study

This study aims to estimate the free sugars intake, identify the primary food sources of free sugars, and explore the relationship between free sugars intake and dental caries among Chinese adolescents. This cross-sectional study included 1517 middle-school students aged 12–14 years in Changsha city, China. Adolescents completed a 12-item Food Frequency Questionnaire (FFQ) and oral health assessment. The students’ dental caries experience was available as DMFT score (number of decayed, missing, and filled permanent teeth). Statistical analyses included the Mann–Whitney test, Kruskal–Wallis test, Chi-square test, and binary logistic regression model. The average intake of free sugars was 53.1 g/d in adolescents, and 43.2% of the students consumed more than 50 g of free sugars daily. The primary contributor to free sugars was sugar-sweetened beverages (SSBs). Age, boarders, and high family income were risk factors for excessive free sugars intake (p < 0.05), and increased free sugars intake was a risk factor for dental caries (odds ratio, OR = 1.446, 95% confidence interval: 1.138–1.839). Both the free sugars intake and dental caries prevalence in Chinese adolescents were high. Targeted interventions are urgently needed to address the excessive consumption of free sugars and improve Chinese adolescents’ oral health.     

离体牙多次粘结托槽的抗张强度测定

①目的　研究牙面多次酸蚀粘结托槽抗张强度的变化。②方法　选择因正畸需要而拔除的前磨牙为实验样本 ,分为 3组 ,每组 10颗牙齿。第 1组为首次酸蚀粘结托槽 ;第 2 ,3组为第 2 ,3次酸蚀粘结托槽。以材料力学实验机分别测定其抗张强度 ,统计每一牙面上的粘结剂残留量进行ARI计分 ,并对各组进行扫描电镜观察。③结果　 3组粘结托槽抗张强度比较 ,差异无显著性 (F =0 .175 ,P >0 .0 5 ) ;3组粘结剂残留指数 (ARI)计分比较 ,差异无显著性 (Hc=2 .2 38,P >0 .0 5 ) ;电镜观察 1,2次酸蚀的牙釉质表面 ,其蜂窝结构在不断增多。④结论　牙面的第 2 ,3次酸蚀粘结托槽仍能获得满意的粘结强度。