Effects of academic stress on oral hygiene – a potential link between stress and plaque‐associated disease?

BACKGROUND: While there seems to be a common belief that psychosocial stress affects oral hygiene behavior, this assumption has rarely been proved. The present study thus aims to analyse stress effects on oral hygiene. MATERIAL AND METHODS: 16 matched pairs of medical students each consisting of 1 student participating in a major academic exam and 1 control without current academic stress, were formed on the basis of baseline plaque levels. At baseline, a professional tooth cleaning was performed. On the last day of exams, students answered questionnaires about oral hygiene during the exams and were afterwards asked to attend for a 2nd dental examination, of which they had no prior knowledge. RESULTS: On the last day of exams, approximately 6 weeks after professional tooth cleaning, 20.9+/-18.3% of control students' sites but only 10.5+/-9.3% of exam students' sites were found to be free of any plaque (p=0.022). Differences were most obvious at oral, as compared to vestibular, sites. Exam students reported a reduction in thoroughness (p=0.019) but not of frequency of oral hygiene behavior. CONCLUSION: The study strongly supports the assumption that psychosocial stress may induce neglect of oral hygiene and increase of plaque accumulation.     

The mechanism of action of chlorhexidine

Controversy exists concerning the mode of action of chlorhexidine in plaque inhibition. This study attempted to determine whether an oral reservoir of chlorhexidine was necessary for plaque inhibition. Plaque growth on enamel under the influence of topically applied or rinsed chlorhexidine was closely monitored by clinical scoring, bacterial culturing and scanning electron microscopy. Thus, 3 subjects wore removable acrylic appliances containing enamel inserts. In the first regimen, inserts on one side of the appliances were exposed to 0.2% chlorhexidine and on the other, water for 1 min twice a day for 14 days. In the second regimen, subjects rinsed with 0.2% chlorhexidine for 1 min twice a day for 14 days with the appliances in situ. Results demonstrated that plaque growth assessed by the 3 study methods was very small on chlorhexidine-treated inserts by comparison with water-treated specimens. Importantly, inserts treated with chlorhexidine topically or by rinsing could not be distinguished by any method of evaluation. It is concluded that chlorhexidine achieves plaque inhibition as a result of an immediate bactericidal action during the time of application and a prolonged bacteriostatic action as a result of adsorption to the pellicle coated enamel surface. Consistent with other clinical studies, it is apparent that a progressively desorbing oral reservoir of antiseptic is not the mechanism by which chlorhexidine achieves plaque inhibition on teeth.     

含抗变形链球菌IgY抗体的溶液对菌斑的作用

目的　观察含 0 1%抗变形链球菌IgY抗体的溶液对变形链球菌及菌斑量的作用效果。方法　采用双盲法 ,试验组 4 4名小学三年级学生使用含IgY抗体的溶液 2 1d ,对照组 4 1人使用安慰剂。试验前后对所有学生的菌斑指数、菌斑量、唾液和菌斑中的变形链球菌进行了检测。结果　试验组学生试验前的菌斑重量是 (46 4± 31 2 )mg ,试验后的菌斑重量是 (36 6± 2 5 6 )mg ,试验前后的差异有极显著性 (P =0 0 0 7) ,与试验前相比菌斑量减少了 2 1 1%。对照组学生的菌斑重量在试验前后分别是 (45 0± 2 3 8)mg和 (41 2± 2 5 9)mg ,二者差异无显著性 (P =0 2 86 )。唾液和菌斑中的变形链球菌量没有显著变化。结论　含 0 1%抗变形链球菌IgY抗体的溶液有减少菌斑形成的作用。     

老年人高龋患者牙菌斑中变形链球菌临床分离株耐酸能力的研究

目的:分析老年人高龋患者牙菌斑中,变形链球菌临床分离株(血清型C)在酸性条件下生存的耐酸能力。方法:体外培养从老年人高龋患者、无龋者牙菌斑中分离的101种不同基因型变形链球菌株临床分离株(血清型C),检测菌株在不同的pH条件下的耐酸能力。结果:老年人高龋患者口腔中分离出的变形链球菌临床分离株耐酸能力明显高于无龋组,与国际参考菌株无明显的统计学差异。同时研究发现,在老年人高龋患者同一个体的口腔中,变形链球菌临床分离株耐酸能力存在明显差异。结论:老年人高龋患者牙菌斑中变形链球菌临床分离株(血清型C)的高致龋性,与其携带有耐酸能力强的菌株关系密切。     

Antibiotic resistance of subgingival species during and after antibiotic therapy

AIM: The purpose of the present investigation was to determine the percentage and identity of antibiotic-resistant species in subgingival plaque and saliva samples from chronic periodontitis patients treated by scaling and root planing followed by orally administered amoxicillin or metronidazole. METHOD: In all, 20 chronic periodontitis patients were selected for study. After clinical and microbiological monitoring, subjects were randomly assigned to receive either orally administered amoxicillin at the dosage of 500 mg, 3 times daily for 14 days or orally administered metronidazole at the dosage of 250 mg, 3 times daily for 14 days. For the antibiotic resistance determinations, subgingival plaque samples were taken from six posterior teeth at baseline, and 90 days; and from two randomly selected teeth at 3, 7 and 14 days during and after antibiotic administration. Samples were plated on enriched blood agar plates with or without either 2 micro g/mL metronidazole or 2 micro g/mL amoxicillin. Colonies were counted at 7 days. Significant differences in percentage of resistant organisms over time were determined by the Quade test. Microbial growth was washed from antibiotic-containing media and the identity of species determined using checkerboard DNA-DNA hybridization. Data were compared with those obtained in a previous study from subjects receiving SRP only or SRP followed by 14 days of orally administered doxycycline. The level of doxycycline used to determine antibiotic resistance in that study was 4 micro g/mL. RESULTS: The mean percentage of resistant isolates increased during antibiotic administration and returned to baseline levels by 90 days post therapy. The mean percentages (+/- SEM) of isolates resistant to 2 micro g/mL metronidazole were 53 +/- 9, 65 +/- 9, 79 +/- 4 and 69 +/- 7 at baseline, 3, 7 and 14 days during antibiotic administration, and 57 +/- 4, 64 +/- 5, 62 +/- 7 and 47 +/- 6 at 3, 7, 14 and 90 days after antibiotic administration. At the same time points, the percentage of resistant isolates to amoxicillin was 0.5 +/- 0.2, 22 +/- 12, 14 +/- 5 and 37 +/- 11 during, and 31 +/- 11, 8 +/- 3, 3 +/- 2 and 3 +/- 0.6 after, administration. Antibiotic-resistant isolates of resistant species detected during or after therapy were also detected prior to therapy. The most prevalent resistant species in the metronidazole-treated group were: A. naeslundii 1, S. constellatus, A. naeslundii 2, S. mitis, S. oralis, A. odontolyticus, S. sanguis, and in the amoxicillin-treated group: S. constellatus, P. nigrescens, E. saburreum, A. naeslundii 1, S. oralis, P. melaninogenica and P. intermedia. CONCLUSIONS: Systemic antibiotic administration transiently increased the percentage of resistant subgingival species, but a major component of subgingival plaque remained sensitive to the agents during their administration. Antibiotic-resistant isolates of resistant species could be detected in samples both prior to and after therapy. However, % antibiotic-resistant isolates returned to baseline levels 90 days after antibiotic administration.     

2种胶姆糖对菌斑pH值的影响

目的：观察咀嚼2种胶姆糖后口腔菌斑pH值的变化情况.方法：选择8例健康受试者（年龄23～27岁,男4例,女4例）参加3次试验,每次实验开始前停止刷牙24h,在使用10%的蔗糖溶液漱口前以及漱口后5、10、15、20min,用Beetrode pH微电极测量口腔菌斑的pH值,作为基线值.1周后先测量静息pH值,再用蔗糖溶液漱口,1min后给予无糖胶姆糖咀嚼,在5、10、15、20min时间点,分别测量非咀嚼侧的菌斑pH值.1周后重复上述实验,胶姆糖改为含茶多酚胶姆糖.应用SPSS10.0统计软件包对数据进行单因素方差分析和SNK分析.结果：与基线值比较,咀嚼2种胶姆糖都能有效防止由于含漱蔗糖水导致的菌斑pH值下降,并使pH值维持在静息pH值以上.2种胶姆糖之间无显著性差异（P＞0.05）.结论：咀嚼2种胶姆糖均能防止菌斑pH值下降,减少患龋危险.     

咀嚼无糖口香糖对含漱蔗糖溶液后牙菌斑原位pH值的影响

目的 通过对牙菌斑原位pH值变化的动态监测，观察咀嚼无糖口香糖对牙菌斑原位pH值的影响。方法 采用受试者自身对照的临床试验方法，选择16名健康成人志愿者为受试者，年龄23～32岁，其中男性6名，女性10名。首先测定受试者48h菌斑的静止pH值，以及受试者用10％蔗糖溶液含漱1min后在5、10、20和30min时菌斑的pH值，取得受试者的Stephan曲线作为基线对照；而后观察咀嚼两种益达无糖口香糖对含漱10％蔗糖溶液后菌斑pH值变化的影响。菌斑原位pH值的测定采用pH微电极接触法在口内直接测量。结果 含漱10％蔗糖溶液后立即开始咀嚼无糖口香糖可使菌斑pH值在各检测时间点(含漱10％蔗糖溶液后5、10、20和30min)均维持在静止pH水平，无明显下降；含漱10％蔗糖溶液后在5min时开始咀嚼无糖口香糖则使菌斑pH值从含漱蔗糖溶液后5min时的5．59迅速回升至10min时的6．98。结论 受到蔗糖攻击后，咀嚼无糖口香糖可迅速缓冲菌斑的酸性产物，升高菌斑pH值。     

Effect of chlorhexidine on dental plaque and gingivitis in mentally retarded children

ABSTRACT The purpose of the investigation was to determine the effect of chlorhexidine mouthrinses as a supplement to toothbrushing in the plaque control of mentally retarded children. Fifty-four mentally subnormal children 7–14 years of age took part in the investigation. During the first period, half of the children rinsed their mouths with 0.2 % chlorhexidine gluconate solution twice a day. The rest of the children used a placebo mouth-rinse. After an 8-week interval a “cross-over” experiment was carried out during which a 0.1 % chlorhexidine solution was used. Plaque and gingival indices were scored at the beginning of each period, after 3 weeks, and at the termination after 6 weeks. The results revealed that mouthrinses with 0.1 % as well as 0.2 % chlorhexidine gluconate reduced plaque and gingivitis in mentally retarded children. The results were statistically significant (P < 0.05) for both concentrations. Furthermore, the investigation confirmed the occurrence of certain side effects such as discoloration of teeth and tongues.     

变形链球菌活性氧代谢的酶学基础

目的 :观察不同培养条件下变形链球菌代谢产生活性氧的情况 ,研究变形链球菌活性氧代谢的酶学基础 ,探讨变形链球菌活性氧代谢产物对菌斑微生态的作用。方法 :采用化学发光法检测变形链球菌培养液中超氧化物歧化酶 (superoxidedismutase ,SOD)含量 ;采用电子自旋捕捉法检测不同培养条件下变形链球菌产生活性氧的情况及还原型尼克酰胺腺嘌呤二核苷酸 (nicotinamideadeninedinucleotidereduced ,NADH)对次黄嘌呤—黄嘌呤氧化酶体系和Fe —H2 O2 体系产生活性氧的影响。结果 :在生理盐水培养条件下 ,变形链球菌培养液中能检测到特征性的二甲基吡咯氮氧化物 (dimethylpyridineN -oxide ,DMPO) -O2 ·和DMPO -OH·的电子自旋共振 (elec tronspinresonance ,ESR)信号 ;外源性糖使变形链球菌培养过程中产生的特征性ESR信号增强 ;美兰则使ESR信号消失 ;NADH使得次黄嘌呤—黄嘌呤氧化酶体系和Fe —H2 O2 体系的ESR信号明显减弱甚至消失 ;在变形链球菌培养液中检测到SOD。结论 :不同培养条件下变形链球菌代谢产生O2 ·和OH·的量不同 ,NADH氧化酶催化的反应可能是变形链球菌产生活性氧的主要来源。     

Effect of oxybenzone on PGE2-production in vitro and on plaque and gingivitis in vivo

OBJECTIVES: To study the effect of oxybenzone on prostaglandin E2 (PGE2) production in cell culture and to evaluate the effect of an oxybenzone-containing dentifrice on plaque and gingivitis in a 6-week clinical trial. MATERIAL AND METHODS: Human embryo palatal mesenchyme (HEPM) cells were used for testing the inhibition of IL-1beta-stimulated PGE2-production in vitro by different concentrations of oxybenzone. For the in vivo study, a total of 66 individuals with a Quigley & Hein plaque index of at least 1.5 and an Ainamo & Bay gingival index of at least 0.2 were included in a double-blind clinical trial with two cells and a parallel design. Two compositions of fluoride dentifrice were used, one with the addition of 0.5% oxybenzone, and one without. Plaque and gingival index were obtained at three time points: (1) at baseline, (2) after 3 weeks, and (3) after 6 weeks. RESULTS: A dose-dependent inhibition of PGE2-production was found in the HEPM cell culture following oxybenzone exposure. In the clinical trial, a 25% reduction of gingival index was observed in the oxybenzone group (p<0.001) after 6 weeks as compared with 2% for the placebo group. CONCLUSIONS: These findings indicate that PGE2-production is reduced by oxybenzone in vitro and that the use of oxybenzone in a dentifrice reduces gingivitis in vivo.