Fluoride and organic weak acids as modulators of microbial physiology

Fluoride is widely used as an anticaries agent in drinking water and a variety of other vehicles. This use has resulted in major health benefits. However, there are still open questions regarding the mechanisms of anticaries action and the importance of antimicrobial effects in caries reduction. Fluoride acts in multiple ways to affect the metabolism of cariogenic and other bacteria in the mouth. F(-)/HF can bind directly to many enzymes, for example, heme-containing enzymes or other metalloenzymes, to modulate metabolism. Fluoride is able also to form complexes with metals such as aluminum or beryllium, and the complexes, notably AlF(4)(-) and BeF(3)(-).H(2)O, can mimic phosphate with either positive or negative effects on a variety of enzymes and regulatory phosphatases. The fluoride action that appears to be most important for glycolytic inhibition at low pH in dental plaque bacteria derives from its weak-acid properties (pK(a)=3.15) and the capacity of HF to act as a transmembrane proton conductor. Since many of the actions of fluoride are related to its weak-acid character, it is reasonable to compare fluoride action to those of organic weak acids, including metabolic acids, food preservatives, non-steroidal anti-inflammatory agents and fatty acids, all of which act to de-energize the cell membrane by discharging DeltapH. Moreover, with the realization that the biofilm state is the common lifestyle for most microorganisms in nature, there is need to consider interactions of fluoride and organic weak acids with biofilm communities. Hopefully, this review will stimulate interest in the antimicrobial effects of fluoride or other weak acids and lead to more effective use of the agents for disease control and other applications.     

Fluoride Ingestion After Brushing with a Gel Containing a High Concentration of Fluoride

The aim of the study was to evaluate the amount of fluoride remaining in the oral cavity of children after brushing with fluoride gel (1.25% F). The study involved six groups of 7-year-old and six groups of 11-year-old children. The procedure was carried out according to the manufacturer’s recommendations. Fluoride concentrations were determined using ion-selective fluoride electrode. No statistically significant difference was found between the amount of fluorides that remained in the oral cavity of younger and older age group (1.2 and 1.3 mg, respectively; p > 0.05). The amount of fluorides swallowed during the procedure in both age groups proves to be within acceptable limit, as far as risk of acute poisoning symptoms is concerned. The individual daily fluoride exposure during the day of procedure seems to be twice as high compared to average fluoride intake from diet and dentifrice, and it does not exceed Tolerable Upper Intake Level for children more than 8. In younger children, it seems justifiable to reduce the amount of the preparation applied on a toothbrush, especially when daily use of the gel is recommended.     

Polymorphisms in sweet taste genes (TAS1R2 and GLUT2), sweet liking,and dental caries prevalence in an adult Italian population

The aim of the study was to assess the relationship between sweet taste genes and dental caries prevalence in a large sample of adults. In addition, the association between sweet liking and sugar intake with dental caries was investigated. Caries was measured by the decayed, missing, filled teeth (DMFT) index in 647 Caucasian subjects (285 males and 362 females, aged 18–65 years), coming from six villages in northeastern Italy. Sweet liking was assessed using a 9-point scale, and the mean of the liking given by each individual to specific sweet food and beverages was used to create a sweet liking score. Simple sugar consumption was estimated by a dietary history interview, considering both added sugars and sugar present naturally in foods. Our study confirmed that polymorphisms in TAS1R2 and GLUT2 genes are related to DMFT index. In particular, GG homozygous individuals for rs3935570 in TAS1R2 gene (p value = 0.0117) and GG homozygous individuals for rs1499821 in GLUT2 gene (p value = 0.0273) showed higher DMFT levels compared to both heterozygous and homozygous for the alternative allele. Furthermore, while the relationship sugar intake–DMFT did not achieve statistical significance (p value = 0.075), a significant association was identified between sweet liking and DMFT (p value = 0.004), independent of other variables. Our study showed that sweet taste genetic factors contribute to caries prevalence and highlighted the role of sweet liking as a predictor of caries risk. Therefore, these results may open new perspectives for individual risk identification and implementation of target preventive strategies, such as identifying high-risk patients before caries development.

Electronic supplementary material

The online version of this article (doi:10.1007/s12263-015-0485-z) contains supplementary material, which is available to authorized users.     

健康儿童与龋齿儿童口腔菌群差异研究

目的 探究龋齿儿童和健康儿童口腔菌群结构及多样性的差异,为该类患儿的治疗提供参考。方法 应用16S rRNA基因V3-V4区高通量测序技术分析90名2～12岁儿童的口腔样本,对比其口腔菌群差异。结果儿童口腔存在核心微生物群,多个菌属的流行度大于90.00%,包括链球菌属（100.00%）、嗜血杆菌属（98.89%）、奈瑟菌属（97.78%）等。丰度前五的菌门均为厚壁菌门、变形菌门、放线菌门、拟杆菌门、梭杆菌门。龋齿儿童和健康儿童口腔菌群多样性指数差异有统计学意义（P<0.05）。LEfSe分析表明,龋齿儿童和健康儿童口腔无色杆菌属、假单胞菌属、约翰森菌属等的丰度差异有统计学意义（均P<0.05）。KEGG通路预测表明,龋齿儿童口腔菌群在免疫系统、形成与再生、细胞运动、聚糖的生物合成和代谢等通路上富集程度上升。结论 龋齿儿童与健康儿童口腔菌群的结构、物种多样性以及群落功能均存在显著差异。     

Secretor status and dental caries in Iceland

Abstract The proportion of non-secretors of ABH blood-group substances among Icelanders is one of the highest recorded for European countries. Dental caries prevalence is also very high. In this study of dental caries in young adults mean number of decayed, missing and filled teeth for secretors were 17.4 and for non-secretors 19.9 ( P < 0.05). A majority of patients seeking free dental treatment in the Dental School were non-secretors (62.7%) significantly more than the proportion of non-secretors in the general population (36%; P < 0.01). It is postulated that blood group substances may interfere with the adherence of Streptococcus mutants to teeth.     

南京市玄武区3～5岁儿童龋病的影响因素分析及对生长发育和营养素摄入的影响

摘要 目的：对南京市玄武区3～5岁儿童患龋病进行流行病学调查,并分析患龋病的影响因素,及其对生长发育和营养素摄入的影响。方法：2020年3月~2022年2月期间,采用多阶段分层等容量随机抽样方法,随机抽取南京市玄武区6所幼儿园,共抽取792名3～5岁儿童,实际完成调查788人,响应率99.49%。记录南京市玄武区3～5岁儿童龋病发生情况,根据有无龋病发生分为龋病组（n=361）和无龋病组（n=427）。应用单因素和多因素Logistic回归性分析南京市玄武区3～5岁儿童龋病发生的影响因素。并观察龋病发生对儿童生长发育和营养素摄入的影响。结果：788例3～5岁儿童中,检查出存在龋病361人,发病率为45.81%。单因素分析显示,南京市玄武区3～5岁儿童龋病发生与年龄、喂养方式、糖摄入频次、睡前食用甜点、刷牙次数、开始刷牙年龄、家长口腔健康知识水平有关（P<0.05）。多因素Logistic回归性分析结果显示：年龄为5岁、喂养方式为全母乳、糖摄入频次为≥2次/d、睡前食用甜点是南京市玄武区3～5岁儿童龋病发生的危险因素（P<0.05）,而家长口腔健康知识水平较高是南京市玄武区3～5岁儿童龋病发生的保护因素（P<0.05）。无龋病组的身高、体重、胸围、肺活量均大于龋病组（P<0.05）。龋病组的能量、蛋白质、脂肪、钙、铁、锌、维生素C、叶酸低于无龋病组（P<0.05）。结论：南京市玄武区3～5岁儿童龋病的发病率较高,龋病对生长发育和营养素摄入均有一定的影响,而年龄、喂养方式、糖摄入频次、睡前食用甜点、家长口腔健康知识水平均是龋病发生的影响因素。     

罗伊乳杆菌对致龋变形链球菌拮抗作用的研究

目的研究罗伊乳杆菌对变形链球菌的拮抗作用,初步了解产生拮抗作用的原因。方法利用罗伊乳杆菌无菌上清液,应用双层平板打孔法测定其抑菌效果,再通过滤纸片抑菌法对罗伊乳杆菌发酵的酸乳制品与普通酸乳制品对变形链球菌的抑菌作用进行比较,用饱和硫酸铵沉淀法分析产生拮抗作用的原因。结果罗伊乳杆菌有显著抑菌活性（P〈0.05）,仅罗伊乳杆菌的发酵乳样品对变性链球菌产生直径为6.3mm抑菌圈,80%饱和硫酸铵沉淀的细菌素抑菌活力最强,蛋白酶K处理后无明显抑菌圈。结论本研究证明了罗伊乳杆菌的代谢产物以及罗伊乳杆菌发酵的酸奶制品对致龋菌变形链球菌有着明显的拮抗作用。     

Ancient dental calculus and diet

Dental calculus has been often considered as a consequence of dietary habits, mainly related to the post Neolitic agricultural development. The presence of fossilized bacteria in the Kebara 2 teeth, aged 60.000 years BP, and the similarity of oral pathologies in pre and post Neolithic samples confirm the multifactorial etiology of oral diseases in general and dental calculus in particular.     

Log-linear analysis of dental caries occurrence in four skeletal series.

Four skeletal series (Corinth, Greece; Gran Quivira, New Mexico; Semna South, Sudanese Nubia, and a large group from scattered sites in England) were coded for sex, jaw, tooth group, dental attrition, dental caries, site and time period. Through thec concepts of a basal level of caries and a cariosity gradient, a single model was found which best described the occurrence of this disease in these samples. All factors were found to contribute significantly to the model. Within the possible subsamples the general characteristics are that the profiles of males, of the mandibulae and of those with light attrition are more likely to have lower overall dental caries levels and to be relatively more carious in the back of the mouth than the front when compared to the pooled sample of all teeth and caries. The opposite is also found to be generally true; the teeth of females, maxillae and heavy attrition are associated with more caries, especially toward the front of the mouth. These results imply that samples appearing otherwise homogeneous display much variation. They also reveal distinct regularities in the reactions of diverse human groups to dental caries.     

细菌生物膜与龋齿相关性的研究进展

牙菌斑是由多种微生物在牙面上沉积,有机基质互相集聚、交联而形成的生物膜结构,生物膜中微生物相互依存、相互竞争,构成了复杂的微生态关系。牙菌斑生物膜的形成是导致龋齿重要过程。本文综述了细菌生物膜与龋齿发生的关系,以期为龋齿的预防与治疗提供新的思路。     

济南大辛庄遗址商代居民的牙齿疾病

大辛庄遗址位于济南市历城区大辛庄村,是山东省内已知面积最大的一处商代遗址,甲骨文及其他丰富遗存的出土对于鲁北及整个山东地区商文化研究具有重要意义。本文主要从人骨的牙齿健康状况入手,对济南大辛庄商代遗址2003、2010年出土的45例人骨标本的牙病情况,尤其是龋病、牙周病、牙结石以及牙齿磨耗情况进行统计与分析,得知大辛遗址商代人群牙齿疾病的基本情况:1)牙结石的出现率男女之间存在明显的性别差异,除此之外其他牙病在罹患率的性别分组上的差异不显著,但均为女性的罹患率要高于男性;2)牙病的罹患率在年龄分组上存在显著差异,随年龄的增长罹患牙病的风险增高;3)龋病、牙周病及牙结石多好发于臼齿;4)重度磨耗牙齿患牙病的风险增加,牙周病表现尤为明显;5)牙病的罹患率不仅受到性别、年龄、牙位以及齿冠磨耗程度的影响,而且与大辛庄商代人群农业经济发展的食物结构有关。     

Health risk assessment of fluoride in water distribution network of Mashhad,Iran

High and low levels of fluoride in drinking waters have been considered as a major public health issue in recent years. This cross-sectional study was conducted over five consecutive years (from 2012 to 2016) in the water distribution network of Mashhad city, Iran with the objectives of determining levels of fluoride and to perform health risk assessment among residents in the study area. Water samples were taken from 30 stations and were analyzed using UV-visible spectrophotometer. The mean annual concentrations of fluoride in all stations during five years of consecutive study were lower than the respective maximum permissible limits (1.5 mg/L) in water as regulated by the WHO. The human health risk assessment was performed by calculating the chronic daily intake and hazard quotient (HQ) of fluoride through human oral intake for adults (men and women) and children for each year during a five-year study. Health risk analysis in this study presented that the non-carcinogenic risk associated with fluoride exposure through drinking water in Mashhad was mostly acceptable because the mean HQ values of fluoride were lower than 1.     

Caries incidence in patients with dementia

One in ten persons over the age of 65 and as many as half the population aged 85 and over have Alzbeimer's disease. Review of the literature reveals substantial decrements in oral health in persons with dementia as measured by denture hygiene, coronal decayed, missing and filled teeth, filled teeth (cervical), percentage of the population with caries. Oral Hygiene Index-simplified, and of sites with plaque, gingival bleeding and calculus. A study of caries incidence is described in 23 male veterans with moderate and advanced dementia of the Alzheimer's type, using a comparison group of male veterans from the Department of Veterans Affairs Dental Longitudinal Study, matching 2 :1 for age, number of teeth and education. Baseline findings indicate significant differences in the numbers of coronal surfaces with decay, root decayed and/or filled teeth and root decayed and/or filled surfaces. Mean annual increments of coronal caries in the dementia group were 2.29±4.29 per 100 surfaces at risk, over twice that in the comparison group (0.88±1.14). For root caries, mean annual increments in the dementia group were 2.38±5.57 per 100 available surfaces, versus 0.31± 0.69 in the comparison group. Despite these large mean differences, the marked variability in these small samples statistical significance in caries increments between the two groups. The article concludes by suggesting some potential modifications to clinical trials of caries preventive agents and some overall research issues in populations with dementia.     

Detection of cariogenic bacterial genes by microchip electrophoresis

Allele-specific PCR primers were designed, based on the dextranase (dex) gene, to identify Streptococcus mutans and Streptococcus sobrinus in dental plaque; subsequently, PCR products were detected via microchip electrophoresis (ME). In order to amplify the dex gene fragment of S. mutans and S. sobrinus, the following two PCR methods were established. Duplex allele-specific PCR primers were designed on a region of low DNA homology; furthermore, 211 and 126-bp fragments were amplified for S. mutans and S. sobrinus, respectively. Common PCR primer for single allele-specific PCR was designed so as to sandwich a region exhibiting high homology and amplify PCR product of different DNA size due to deletion of small DNA fragment in two dex genes. S. mutans and S. sobrinus were amplified, leading to the generation of 202 and 226-bp products, respectively. Analysis of DNA base size by ME in order to achieve efficient separation employed a polymer mixture consisting of hydroxypropyl methylcellulose (HPMC) and polyethylene oxide (PEO). In the presence of a polymer mixture of 0.125% PEO/0.6% HPMC, two PCR products were obtained, displaying degree of separation of 226 bp/202 bp of 2.67 (Rs). Reproducibility (CV%, n = 7) was 0.3%; additionally, separation time was approximately 85 s. This method was applied to the detection of S. mutans and S. sobrinus in dental plaque. Detection of the dex genes of S. mutans and S. sobrinus characterized by quickness, precision and high sensitivity was possible.