乳牙菌斑液pH值与患龋状况及摄糖频率的关系

目的分析乳牙菌斑液pH值与患龋状况及摄糖频率之间的关系。方法将93名北京城区3～5岁儿童，根据患龋情况分为重症婴幼儿龋（Severe Early Childhood Caries，S—ECC）组47名，dt≥5；无龋（Caries Free，CF）组46名，dmft=0。分别收集集合菌斑，应用离子选择性微电极法测定受试者乳牙菌斑液pH值，并进行组间比较；对两组受试者每日摄糖频率进行调查，分析菌班液pH值与摄糖频率的关系；并在S—ECC组分析菌斑液pH值与dt的关系。结果S—ECC组菌斑液pH均值低于CF组，差别有统计学意义；S—ECC组患儿每日摄糖频率高于CF组；乳牙菌斑液pH值与摄糖频率呈负相关关系；S—ECC组菌斑液pH值与dt相关（P〈0、05）。结论乳牙菌斑液pH值与摄糖频率呈负相关关系，并且S—ECC组儿童与CF组儿童相比，其菌斑液有更大的致龋潜能。     

频繁摄食蔗糖对口腔牙菌斑钙、磷、氟储库和龋病相关性的研究

目的:观察不同摄食蔗糖频率对菌斑钙、磷、氟含量变化,及对菌斑下釉质脱矿的影响,评价菌斑钙、磷、氟 储库和龋病的相关性。方法:选取10名志愿者,制作附有3块4mm×4mm×1mm大小釉质块的口内装置,在7天 周期培养菌斑的同时,以0次/d～8次/d不同频率滴加20%的蔗糖溶液,每次作用5min,观察7d后菌斑钙、磷、氟 含量、菌斑重量和釉质脱矿。结果:菌斑钙、磷含量随摄糖频率的升高显著下降(P<0.001),氟含量仅在8次/d频 率时较基线有显著降低(P<0.01),而菌斑重量则显著增加(P<0.001),4次/d和8次/d组釉质块出现脱矿,脱矿 釉质块数目、程度与摄糖频率呈正相关。结论:频繁摄糖减少了菌斑矿物质含量,使其缓冲能力下降,并增加了菌 斑的致龋性。     

乳牙菌斑液磷酸根浓度及其与患龋状况关系的分析

目的 :探讨乳牙菌斑液中磷酸根浓度与儿童患龋状况的关系 ,为乳牙菌斑液及龋病的研究提供基础资料。方法 :对 46名 3～ 5岁儿童 ,用离子色谱仪测定集合菌斑液的磷酸根浓度 ,并检查其患龋状况 ,统计分析乳牙菌斑液磷酸根浓度与儿童患龋状况之间的关系。结果 :乳牙菌斑液磷酸根浓度在无龋组为 (12 .63± 2 .91)mmol/L、有龋组为 (13 .85± 3 .2 8)mmol/L、其中龋病高危组为 (14 .62± 3 .47)mmol/L ,无龋组与有龋组之间无显著性差异 ,无龋组与龋病高危组之间无显著性差异。乳牙菌斑液磷酸根浓度与dft、dfs、和CSI无相关性。结论 :乳牙集合菌斑液磷酸根浓度与儿童患龋状况无关 ,菌斑液中单一成分不能反映菌斑的致龋能力。     

先天性心脏病儿童牙菌斑中白色念珠菌的携带情况

目的：研究先天性心脏病儿童牙菌斑中白色念珠菌的携带情况。方法：根据WHO龋齿诊断标准,以115名2～5岁的先心病儿童作为研究对象,其中有龋组86人,无龋组29人,同时选取115例健康儿童为对照组,临床检查记录龋失补牙数（dmft）、龋失补牙面数（dmfs）及可视菌斑指数（VPI）;采集龈上菌斑及龋坏组织,应用SYBR green I荧光定量PCR方法,对各组样本中白色念珠菌含量进行检测,所获得的数据进行统计学分析。结果：先心病组患龋率为74．8％,dmft、dmfs及VPI分别为5．69±5．69、11．83±15．14、43．8％±24．1％;对照组受检儿童患龋率为67．0％,dmft、dmfs、VPI分别为3．53±4．02、5．51±7．40、36．5％±24．1％。两组dmft,dmfs,VPI的差异有统计学意义。儿童牙菌斑中白色念珠菌的含量（Log10 copies/mL）,先心病有龋组龋洞和牙颈部分别为6．71±2．92、5．64±3．11,无龋组为5．03±2．74;正常儿童有龋组龋洞和牙颈部分别为4．01±2．35、3．27±2．14,无龋组为3．43±2．56。先心病儿童与正常儿童牙菌斑中白色念珠菌含量差异具有统计学意义。结论：先心病儿童牙菌斑中白色念珠菌的含量高于正常儿童。口腔中的白色念珠菌,可能成为感染性心内膜炎的菌源之一,使先心病儿童成为感染心内膜炎的易感人群。     

婴幼儿龋菌斑生物膜中白色念珠菌的检出情况

目的初步探讨白色念珠菌检出情况与婴幼儿龋（early childhood caries,ECC）的相关性。方法采用CHROMagar Candida、革兰氏染色及厚膜孢子形成试验,对ECC菌斑生物膜中的白色念珠菌进行分离鉴定,并应用Pearsonχ2检验分析白色念珠菌检出情况与ECC关系。结果白色念珠菌的检出率在ECC组中为44.1%,无龋（caries-free,CF）组为19.2%。ECC组中,男、女生白色念珠菌的检出率分别为59.7%、34.9%;CF组中,白色念珠菌检出率男生为21.1%,女生为18.5%。白色念珠菌的检出率与dmft分级的关联系数为0.35。结论白色念珠菌的检出情况与ECC相关,且白色念珠菌的检出情况与dmft的分级具有关联性。     

牙菌斑液对牙釉质矿物的饱和程度与龋活动性的关系

为了解菌斑液对牙齿矿物饱和度随糖漱口的变化，以及与龋活动性的关系，作者选择２２例年龄相同的大学生，按龋齿情况，将其分为３组。第１组无龋（无龋组），第２组ＤＭＦＳ大于１０但无活动性龋（普通龋组），第３组ＤＭＦＳ大于１０且有活动性龋（活动性龋组），测定各受试者在静止时、用蔗糖液漱口后３ｍｉｎ和７ｍｉｎ时的菌斑液中有机酸、ｐＨ值、钙离子活度（有效离子浓度）和无机成分的含量，并计算对于釉质矿物的饱和度。结果表明，糖漱口之后菌斑液乳酸浓度升高、ｐＨ值降低、总钙和离子钙浓度增加。活动性龋组的菌斑液在糖漱口后ｐＨ值和饱和度降低的幅度明显大于无龋组和普通龋组。结论：牙菌斑液对牙齿矿物的饱和度是指示个体接受致龋食物后牙齿脱矿倾向的敏感指标。     

菌斑固相消耗糖后缓冲容量的变化与龋易感性的关系

目的研究牙菌斑固相代谢糖后缓冲容量的变化与龋易感性的关系。方法选择成年高龋者(DMFS≥10,DS≥5)及无龋者(DMFS=0)各10名,分别取4种糖消耗情形下的牙菌斑,即基线菌斑、一次漱糖后即刻菌斑、持续耗糖菌斑和漱糖后恢复期菌斑。样本经离心干燥获得菌斑固相成分,以25mmol/LKCl制备10mg/ml的混悬液,用0.1mmol/LHCl滴定以测定初始pH至pH4的缓冲总量和pH5.2~4区段的缓冲容量,同时对各组进行细菌计数。结果消耗糖后菌斑固相的缓冲总量均比基线值(208.793±73.338μmolH /g)低,在pH5.2~4区段,一次耗糖即刻和漱糖前的缓冲容量相同,分别为112.243±28.124μmolH /g和124.773±27.886μmolH /g,持续耗糖后下降至93.358±18.356μmolH /g,恢复期菌斑固相的缓冲容量(144.905±36.857μmolH /g)显著上升。不同龋易感个体缓冲容量间的差异并无显著性。结论糖消耗过程影响菌斑固相的缓冲力,缓冲容量可能不是一个指示龋易感性的敏感指标。     

牙菌斑液成分在判断个体龋易感性中的作用

目的研究糖代谢后牙菌斑液化学成分与龋的关系,探求判别个体龋易感性中的因子.方法6～7岁儿童,无龋(dmfs=0)12名,高龋(dmfs≥10)6名,低龋(3≤dmfs＜10)7名.毛细管电泳技术(Beckman,Pace5000)检测有机酸、磷酸和无机阳离子.结果无龋组乳酸和低pKa酸的水平显著低于低龋组(P=0.002)和高龋组(P=0.01).多元逐步回归法和Logist回归法筛选出乳酸为龋的判别因子(P=0.0644).结论糖代谢7min后菌斑液中乳酸浓度的变化具有判断个体对龋易感程度的作用.     

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.     

人工牙菌斑致釉质表面钙,磷变化的化学分析

目的：采用多菌系人工龋菌斑模型系统对菌斑－牙釉质界面钙磷运动情况进行化学分析。方法：用微量化学分析法测定钙、磷含量。结果：菌斑一经接触糖后，ｐＨ开始下降，菌斑液中钙磷浓度随之增加，并且同ｐＨ下降程度成正相关。结论：认为早期龋形成中钙磷离子运动直接影响早期釉质龋表层下损害的形成。     

Relationship among dental plaque composition,daily sugar exposure and caries in the primary dentition

The relationship among daily sugar exposure, dental plaque composition and caries patterns in the primary dentition is not known. Three groups of 20 children (18-48 months old) were studied: (1) caries-free (CF), (2) presenting pit and fissure caries (PFC), and (3) with nursing caries (NC). Dental caries index (dmfs) was assessed and the frequency of daily sugar exposure (TS) and its forms were estimated by questionnaires. Fluoride (F), calcium (Ca), inorganic phosphorus (P(i)), insoluble polysaccharide (IP) and mutans streptococci were quantified in dental plaque. The three groups of children were statistically different regarding daily sugar exposure. Concentrations of F, Ca and P(i) were lower and the IP and mutans streptococci statistically higher in dental plaque from NC children than those from CF children. PFC children also showed statistically lower F and P levels in their plaque than CF children. Statistically significant correlations were found between IP, TS and dmfs from NC and PFC children. A statistically significant correlation between mutans streptococci in plaque from anterior teeth and dmfs for NC children was also observed. These results suggest that the dietary sugar experience changes the biochemical and microbiological composition of dental plaque, which could partly explain the different caries patterns observed in primary dentition.     

Plaque minerals in the prediction of caries activity

BACKGROUND/AIMS: Attempts to identify subjects who will develop caries lesions in future years have been only moderately successful, suggesting that one or more important risk factors are being overlooked. The aim of this study was to validate the use of plaque calcium, phosphate and fluoride concentrations as significant risk factors in caries. METHODS: DMFS and DMFT rates were measured three times over 2 years in a group of rural Chinese schoolchildren initially aged 12 years and not living in a high-fluoride area. At the baseline and year 1 examinations, dental plaque was accumulated for 3 days and, after collection, was analysed for Ca, P and F. Plaque scores, dental health behaviour and parents' occupation data were also recorded. RESULTS: The mean DMFS increment over 2 years was 1.14 with a range of -2 to +9. Regression analysis taking all factors into account identified only plaque Ca concentration, baseline DMFS score and toothbrushing frequency as significant factors in identifying high-risk individuals. Plaque Ca also showed predictive ability on its own. For example, when high caries was defined as 3+ new DMFS and a Ca cut-off value of 200 nmol/mg dry wt was selected, sensitivity was 0.84 and specificity 0.38. However, with this cut-off value the percentage predicted to have high caries risk was unrealistically high at 66%. As in several other studies, baseline caries score was a useful predictor of future caries. CONCLUSION: Low plaque Ca concentration showed a modest ability to predict future caries, and since it is implicated directly in the chain of events leading to caries, its use in caries prediction should be considered further. Plaque P and F showed no predictive ability in this study.     

Streptococcus mutans and Streptococcus sanguinis colonization correlated with caries experience in children

The aim of this study was to examine the colonization of Streptococcus mutans and Streptococcus sanguinis in the oral cavity and the association with severe early childhood caries (S-ECC). Saliva and plaque samples were collected from 14 S-ECC children and 8 caries-free (CF) children. All S-ECC children were S. mutans positive; 100% of CF children and 93% of S-ECC children were S. sanguinis positive. The children's caries severity was positively correlated with levels of S. mutans (p < 0.001), total oral streptococci (p < 0.01), total cultivable oral bacteria (p < 0.05), and children's age (p < 0.05). Logistic regression analysis showed that the interaction of S. sanguinis with S. mutans was a significant factor associated with the caries status in children, suggesting that the relative levels of these two microorganisms in the oral cavity play an important role in caries development.     

Composition and buffer capacity of pooled starved plaque fluid from caries-free and caries-susceptible individuals

The composition of pooled starved plaque fluid from six population samples, grouped according to age (8-11, 12-16, 8-17, 18-22 years) and caries status (caries-free, CF, DMFS = 0; caries-susceptible, CS, DMFS greater than 10), was determined by means of ion chromatography. Prior to plaque collection, all subjects abstained from oral hygiene for 48 hours and fasted overnight. In addition, selected subjects also received a dental prophylaxis one week prior to plaque collection. Plaque samples from each group were pooled under mineral oil and centrifuged at 15,000 g (ambient temperature) for 45 minutes. Supernatants were then analyzed for organic acids, inorganic anions, and mono- and divalent cations. Plaque fluid samples from CF and from the CS subgroups were also titrated with standard HCl for exploration of the inherent buffer capacity. The ions Na+ NH4+, K+, Ca2+, Mg2+, Cl-, phosphate, and carbonate were present in all samples analyzed. Formic, acetic, propionic, butyric, and trace amounts of isobutyric and isovaleric acids were detected, with acetic and propionic acids comprising between 85 and 94% of the total acids. Little (less than 1 mmol/L) to no succinic or lactic acid was detected in starved plaque fluid. No apparent difference was detected in the composition and saturation status of pooled starved plaque fluid from CF and CS individuals. These results suggest that caries susceptibility is not necessarily correlated with the plaque fluid composition of pooled starved plaque. In addition, no apparent difference in the inherent buffer capacities of these samples could be detected, consistent with the noted similarities in composition.(ABSTRACT TRUNCATED AT 250 WORDS)     

The effect of sucrose application frequency and basal nutrient conditions on the calcium and phosphate content of experimental dental plaque

A reduced pool of calcium in dental plaque would be expected to increase the ability of plaque fluid to dissolve the underlying enamel when the pH falls during sugar exposure. We have examined the relationship between frequency of sugar application and Ca and P(i) concentrations in artificial mouth plaque microcosm biofilms. Ten plaques were grown simultaneously from a human saliva inoculum using a continuous flow of simulated saliva, DMM, supplemented with either urea or glucose to modulate the resting pH. In addition the plaques received sucrose applications of varying frequency: 12-, 8-, 6-, or 4-hourly, or not at all. After 15 days the plaques were sampled by taking 4 full-thickness specimens of each, and acid-extractable Ca and P(i), and alkali-soluble protein and carbohydrate were determined. Ca and P(i) concentrations were in a range comparable with those in human plaque, except in the DMM + urea plaque receiving no sucrose, when concentrations were higher. Plaque Ca concentration decreased significantly as sucrose application frequency increased. Increasing sucrose application frequency also reduced the protein, i.e. the cell biomass, content of the plaques and, in the case of DMM + urea plaques, increased the water-insoluble hexose content, presumably extracellular polysaccharide. Reduced biomass was partly due to the bulking of plaque with extracellular polysaccharide, but the marked effect of urea on polysaccharide formation is not understood. This study shows that increasing frequency of sugar application alters dental plaque by reducing its mineral protection capacity.     

Risk factors for severe early childhood caries in children younger than 4 years old in Beijing, China

PURPOSE: The purpose of this study was to compare cariogenic factors and acidogenic ability of bacteria between severe early childhood caries (S-ECC) and caries-free children in Beijing, China. METHODS: The study consisted of 117 S-ECC children and 129 caries-free children < 4 years old. A questionnaire was designed to collect background information, feeding habits, and oral hygiene practices. Dental plaque samples were collected to test acidogenic ability of bacteria. RESULTS: Compared with the mothers of caries-free children, those of S-ECC children had a lower education level and poorer knowledge of oral hygiene (P < .05). Night-feeding and eating sweets several times a day were significantly more common in S-ECC children than in caries-free children (P < .001). Forty-six S-ECC children but only 2 caries-free children received prechewed food (P < .001). The results of the Cariostat test showed that the majority of the caries-free children (81%) were at a low risk level, and most of the S-ECC children (78%) were at a high risk level (P < .001). CONCLUSIONS: There was strong relationship between high acidogenic ability of bacteria and S-ECC. A lower maternal education level, poor knowledge of oral hygiene, night-feeding, and excessive sugar intake were important contributors to the development of S-ECC.     

Site-specificity of mineral ions in 2-day dental plaque obtained from children and young adults

The aim of this study was to determine the variation in mineral ions (Ca and P) concentrations in 2-day dental plaque taken from different areas of the deciduous and the permanent dentition that may be related to the caries status of tooth surfaces obtained from children and young adults. We also compared those minerals between the deciduous and the permanent dentition. Plaque samples were collected from eight dentition sites, including the upper-anterior-buccal (UAB) and -lingual (UAL), lower-anterior-buccal (LAB) and -lingual (LAL), upper-posterior-buccal (UPB) and -lingual (UPL), lower-posterior-buccal (LPB) and -lingual (LPL) regions. Significant differences among these eight different sites were determined from Ca and P ions concentrations, as well as the Ca/P ratio, calculated by ANOVA. Plaque associated with the LAL region closest to the main salivary ducts and that is less prone to caries, had significantly higher levels of Ca, P ions concentrations, a higher Ca/P ratio than any other dentition areas in both children and young adult subjects. Statistical differences were seen in minerals between children and young adults. Ca ion concentrations in dental plaque from young adults were significantly higher than those of children at the LAL site. Statistical analysis of the relationships between Ca and P ions showed that there were strong associations between Ca and P ions, especially in the UPB, LAL and LPL regions where there is a high exposure to saliva. We conclude that there is a site-specificity of plaque mineral content in both children and young adults, which may reflect the differences in exposure to saliva, resulting in differences in the local cariostatic challenge.     

Composition of pooled plaque fluid from caries-free and caries-positive individuals following sucrose exposure.

The composition of pooled plaque fluid from five population samples was determined before and at selected times (7, 15, 30, and 60 min) after a 10% sucrose rinse. Subjects were grouped according to caries status (caries-free, CF, DMFS = 0; caries-positive, CP, DMFS > 10). Samples were also studied from white-spot surfaces and from sound surfaces of the same mouths of two additional CP groups. Plaque fluid was isolated by centrifugation and analyzed for organic acids, inorganic ions (ion chromatography), and pH (microelectrodes). Prior to sucrose exposure, plaque fluids from the CF subgroups and from sound surfaces of the CP subjects had higher pH values than samples from CP subgroups and from white-spot surfaces, respectively; the ionic compositions were otherwise similar. Starved plaque fluids were also found to be supersaturated with respect to enamel and to a significantly greater degree in the CF samples, suggesting that CF plaque fluid may have a greater remineralization potential than CP samples. Following sucrose exposure, a rapid decrease in plaque fluid pH was observed, which corresponded primarily to lactic acid production. For all times examined, mean pH and DS(En) values were lower and lactic acid concentrations were higher in the CP samples than in the CF samples; noted differences were statistically significant at 7 min for pH and DS(En), and at 7, 15, and 30 min for lactic acid. Lower values of DS(En) suggest that plaque fluid from CP subjects had a measurably greater cariogenic potential.(ABSTRACT TRUNCATED AT 250 WORDS)     

无口腔保健干预牙菌斑液成分的研究

目的 研究长期无口腔保健干预的牙菌斑液粘代谢规律及其致龋力。方法 选择长期不刷牙者４３人,分为无龋组２７人,高龋组１６人,采集１０％蔗糖漱口前后的菌斑,检测菌斑提取液的ｐＨ值、有机酸和无机离子的浓度。结果 糖漱口后,长期菌斑提取注的ｐＨ值,、铵离子浓度降低,乳酸、甲酸升高,与禁食后新形成菌斑的糖代谢规律一致。但糖漱口前后两组菌斑提取液中的单一成分差异均无显著性。结论 长期菌斑与短期菌斑的糖代谢规律