光动力疗法对牙菌斑生物膜内致龋菌的影响及作用机制的研究

目的：探讨以血卟啉单甲醚（hematoporphyrin monomethylether,HMME）为光敏剂的光动力疗法（photo-dynamictherapy,PDT）对牙菌斑生物膜内致龋菌的杀灭作用及机制。方法：以变形链球菌、血链球菌、嗜酸性乳杆菌和粘性放线菌为实验菌株,建立牙菌斑生物膜模型。实验分为4组：HMME-PDT组、HMME-PDT加叠氮钠组、西吡氯铵处理组、生理盐水处理组。平板菌落计数观察牙菌斑内致龋菌的活力,并测定不同处理前后pH的变化值（么pH）观察其对致龋菌产酸能力的影响。结果：与生理盐水组相比,HMME-PDT组和西吡氯铵组牙菌斑内致龋菌的数量（CFU／mL）显著下降（P〈0．05）,其杀菌率分别为94．92％和51．86％;而HMME-PDT加叠氮钠组牙菌斑内致龋菌数量无显著性差异,杀菌率仅为9．47％。么pH值测定结果显示,在一定时间范围内（O～24h）,与生理盐水组相比,HMME-PDT组牙菌斑内致龋菌的产酸能力显著下降。结论：PDT可有效杀灭菌斑生物膜内的致龋菌,并抑制其产酸,同时单线态氧在PDT杀菌过程中起着极其重要的作用。     

新一代高通量技术在龋病相关的口腔菌群宏基因组学研究中的应用

龋病是人类最普遍的感染性疾病,针对龋病的病因学研究、风险评估乃至预防策略是目前研究的重点问题。本研究小组采用新一代高通量技术包括454 FLX Titanium测序、Solexa GA Ⅱ测序及Geochip 3.0功能基因芯片     

氟保护漆Duraphat治疗前牙初期龋损的临床效果

目的 探讨氟保护漆Duraphat对前牙初期龋损白垩色斑块的治疗效果。方法 共纳入并分析120例患者146个前牙唇侧白垩斑病损,分为三组：A组（涂氟保护漆Duraphat＋口腔健康教育组,n = 52）,B组（口腔健康教育组,n = 47）和C组（对照组,n = 47）。由同一位已经过培训的医生采用牙周探针对白垩斑的直径及龋活动性进行评估,同时对研究对象的口腔卫生采用改良菌斑指数进行评估。结果 A组在接受2年的涂氟治疗后其白垩斑直径明显缩小,与另外两组差异有统计学意义（X^2=29.1,P 〈 0.001）,初期龋损白垩色斑块活动性龋的比例明显下降（χ^2=42.5,P 〈 0.001）。结论 氟保护漆Duraphat能有效治疗光滑面的初期龋损。     

氟化物涂膜的临床应用

氟化物的防龋作用较为明显,目前临床上应用的各种氟化物剂型多有其缺点,严重影响了氟化物的临床应用。氟化物涂膜作为一种局部应用氟化物缓释剂型,由于其独特的剂型特点,在防龋、治疗牙本质过敏症和预防正畸过程中牙釉质白斑的发生等多个方面都有着不可替代的优点,因此在许多国家氟化物涂膜已取代了氟化物凝胶的应用。本文就氟化物涂膜的临床应用情况及功能特点作一简要综述。     

高龋无龋幼儿菌斑致龋菌检出及与患龋的关系

目的 比较高龋和无龋幼儿菌斑致龋菌的检出率,分析不同致龋菌检出情况与dmft的关系.方法 调查818名广州城、郊3～4岁儿童患龋情况,根据结果抽取3～4岁高龋和无龋儿童各40名,采集乳磨牙颊面菌斑,用选择性培养基进行分离培养,采用形态学和生化实验的方法进行细菌鉴定.结果 高龋组幼儿变形链球菌、远缘链球菌和乳杆菌的检出率分别是95.0%、32.5%和45.0%,均显著高于无龋组儿童三种细菌的检出率(P＜0.05).高龋组儿童中,同时检出三种致龋菌的儿童的dmft为13.22±3.49,显著高于只检出一种或两种致龋菌的儿童(P＜0.05).结论 高龋儿童变形链球菌、远缘链球菌和乳杆菌检出率高于无龋儿童,菌斑致龋菌的种类越多,造成儿童口腔中具有更多龋齿的危险性也更大.     

Fluoride concentration in supragingival dental plaque after a single intake or habitual consumption of fluoridated milk

The aim of this study was to evaluate the fluoride concentration in supragingival dental plaque after single and repeated intakes of fluoridated milk. The study group consisted of 22 schoolchildren, young adults and adults of both sexes, 8-41 years of age. After a 2-week fluoride depletion period and 3 days of plaque accumulation, 200 ml of fluoridated milk (1g F) was ingested along with a standardized lunch meal. Plaque samples were collected immediately before the intake and after 30, 120 and 240 min. From the adult participants (n = 9), additional samples were colleted after 12 and 18 h. After a fluoride-free washout period of at least 2 weeks, the whole experimental procedure was repeated after 4 consecutive daily intakes of fluoridated milk. The fluoride concentration was determined after micro-diffusion with a fluoride selective electrode. The results showed a statistically significant 3-fold increase of the plaque fluoride levels up to 4 h after the intake. At 12 and 18 h after the intake, the recorded levels went gradually back to baseline. There was no significant difference between the fluoride concentrations in the supragingival plaque after the single intake compared with the repeated intakes. In conclusion, the findings support the suggestion that milk is a suitable vehicle for local fluoride administration into the oral cavity, also when consumed together with a meal.     

Caries-preventive effectiveness of fluoride varnish as adjunct to oral health promotion and supervised tooth brushing in preschool children: A double-blind randomized controlled trial

Objectives

To evaluate the effect of biannual fluoride varnish applications in preschool children as an adjunct to school-based oral health promotion and supervised tooth brushing with 1000 ppm fluoride toothpaste.

Methods

424 preschool children, 2–5 year of age, from 10 different pre schools in Athens were invited to this double-blind randomized controlled trial and 328 children completed the 2-year programme. All children received oral health education with hygiene instructions twice yearly and attended supervised tooth brushing once daily. The test group was treated with fluoride varnish (0.9% diflurosilane) biannually while the control group had placebo applications. The primary endpoints were caries prevalence and increment; secondary outcomes were gingival health, mutans streptococci growth and salivary buffer capacity.

Results

The groups were balanced at baseline and no significant differences in caries prevalence or increment were displayed between the groups after 1 and 2 years, respectively. There was a reduced number of new pre-cavitated enamel lesions during the second year of the study (p = 0.05) but the decrease was not statistically significant. The secondary endpoints were unaffected by the varnish treatments.

Conclusions

Under the present conditions, biannual fluoride varnish applications in preschool children did not show significant caries-preventive benefits when provided as an adjunct to school-based supervised tooth brushing with 1000 ppm fluoride toothpaste.

Clinical significance

In community based, caries prevention programmes, for high caries risk preschool children, a fluoride varnish may add little to caries prevention, when 1000 ppm fluoride toothpaste is used daily.     

Fluoride concentration in plaque in adolescents after topical application of different fluoride varnishes

The aim of the study was to measure the fluoride (F) concentration in plaque after a single topical application of different fluoride varnishes with contrasting levels of F. Thirty adolescents (12–17 years) with fixed orthodontic appliances were randomly assigned to one of three groups: Bifluoride (6% F), Duraphat (2.23% F) and Fluor Protector (0.1% F). The varnishes were applied after professional cleaning in one upper quadrant, leaving the opposite quadrant untreated according to the split-mouth technique. Pooled plaque samples from each quadrant were collected at baseline and 3 days, 7 days and 30 days after the varnish treatment, and fluoride was analysed by microdiffusion. All fluoride varnishes increased the fluoride concentration in plaque compared with baseline, and the mean values varied between 23 and 138 ng F/mg after 3 days, depending on varnish F concentration. Compared with the control quadrant, statistically significant elevations were recorded for Bifluoride after 3 days and 7 days and Duraphat after 3 days, while no significant differences were revealed in the Fluor Protector group. The fluoride concentration in plaque was back to baseline levels for all participants in the Duraphat group after 7 days, while some individuals in the Bifluoride and Fluor Protector groups still registered slightly increased levels after 30 days. The results suggest that fluoride varnish treatments resulted in elevated fluoride levels in plaque adjacent to fixed orthodontic appliances for a period of up to 1 week, although different patterns was disclosed for the various brands. Received: 5 October 1999 / Accepted: 18 November 1999