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.     

A method to study sustained antimicrobial activity of rinse and dentifrice components on biofilm viability in vivo

AIM: To develop an improved method for quantitative assessment of antimicrobial efficacy and substantivity of mouth rinses and dentifrices on in vivo treated plaque. MATERIAL AND METHODS: Nine- and 72-h-old plaques were formed in volunteers carrying out standardized hygiene using NaF-containing dentifrice. Plaques were collected before (baseline) in vivo treatment with dentifrices or chlorhexidine mouth rinse, immediately post-treatment and after 1 or 6 h, dispersed in demineralized water and stained with live/dead stain after which bacteria were enumerated. Dispersed baseline plaques were treated with dentifrices or chlorhexidine to determine antimicrobial efficacy against planktonic bacteria. RESULTS: Baseline plaques revealed 56-41% viable organisms in 9- and 72-h-old plaques, respectively. Treatment of planktonic (dispersed baseline plaque) bacteria resulted in 1-4% viable organisms. Chlorhexidine mouth rinse and dentifrices produced strong immediate antimicrobial effects, but after 1 or 6 h, the proportion of viable organisms in 9-h-old plaques rebounded significantly with only chlorhexidine mouth rinse retaining significant efficacy. Seventy-two-hour-old plaques were less susceptible to antimicrobials, although dentifrices appeared more effective after 6 h than initially, whereas efficacy of chlorhexidine rinse continued to drop with time post-treatment. CONCLUSIONS: The proposed method holds promise for assessment of both immediate and retained antimicrobial actions of oral treatments against dental plaque in vivo.     

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.     

Real-time quantitative polymerase chain reaction for enumeration of Streptococcus mutans from oral samples

This study compared SYBR Green real-time quantitative PCR (qPCR) with standard plate counting for the enumeration of Streptococcus mutans in oral samples. Oral samples (n = 710) were collected from high-caries-risk children for quantification of S. mutans by qPCR using primer pairs. The S. mutans copy number was calculated with reference to a qPCR quantification cycle (Cq) standard curve and compared with the absorbance value at 600 nm of a standard suspension of S. mutans UA159. The S. mutans copy number results were evaluated in relation to standard plate count (SPC) results obtained from each sample following culture on Petri plates containing S. mutans selective media and reported as colony-forming units (CFUs). The mean S. mutans copy number calculated from qPCR was higher than the SPC CFUs (1.3 × 10(6) and 1.5 × 10(5) CFUs, respectively). The qPCR values were usually higher in individual samples and qPCR detected the presence of S. mutans 84% (231/276) of the time that the SPC did not, compared with 33% (4/12) of the time when qPCR failed to detect S. mutans and the SPC did. The qPCR technique was found to be more sensitive for detection of S. mutans from oral samples, a method that is not dependent on the viability of the sample taken and therefore is proposed as a more reliable and efficient means of quantification of S. mutans.     

Serum cytokine levels in periodontitis patients in relation to the bacterial load

Background: Periodontitis is a local inflammatory disease that also has some systemic effects. We investigated the levels of interferon (IFN)‐γ, tumor necrosis factor (TNF)‐α, and interleukin (IL)‐2, ‐4, ‐5, and ‐10 in the serum of patients with periodontitis in relation to the bacterial load in the dental plaques. Methods: Serum cytokine levels in patients with generalized periodontitis and healthy control groups were determined using the cytometric bead array kit. Bacterial load in the dental plaque was determined semiquantitatively by real‐time polymerase chain reaction. The proportions of different lymphocyte subsets were determined in the peripheral blood of patients with periodontitis by flow cytometry. Finally, relationships between the bacterial load in the subgingival plaques of patients with periodontitis and levels of cytokines and counts of lymphocyte subsets were established. Results: Serum levels of IFN‐γ, TNF‐α, and IL‐10 were significantly increased, whereas those of IL‐2 were significantly decreased in patients with periodontitis compared to healthy controls. Increased serum levels of IFN‐γ and TNF‐α in patients with periodontitis were associated with the enhanced dental plaque load with Aggregatibacter actinomycetemcomitans (previously Actinobacillus actinomycetemcomitans) and Porphyromonas gingivalis, respectively. Finally, as revealed by analysis of lymphocyte populations, the presence of A. actinomycetemcomitans and Trepomena denticola was associated with an increased population of CD3^?/CD16⁺ and CD3⁺/CD8⁺ cells, respectively. Conclusion: Certain periodontal pathogens could be associated with an increased level of proinflammatory cytokines in the peripheral blood and thus increased risk of systemic diseases.     

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。     

口腔白斑病中黏着斑激酶对细胞增殖的影响

目的 通过检测黏着斑激酶(FAK)和增殖细胞核抗原(PCNA)在口腔白斑病(OLK)中的表达水平,探讨FAK对细胞增殖的影响.方法 选择2017年1月至2019年12月在安徽医科大学第一附属医院进行OLK手术切除的41例患者作为试验组,根据病理诊断,将试验组41例OLK标本分为OLK上皮单纯增生组(n=10)、OLK上皮轻度异常增生组(n=11)、OLK上皮中度异常增生组(n=13)和OLK上皮重度异常增生组(n=7).另同期选取10例进行囊肿切除术以及智齿拔除术患者的正常口腔黏膜组织作为对照组,采取免疫组织化法检测各组患者的FAK和PCNA表达;同时采用逆转录-聚合酶链反应法检测各组患者FAK mRNA表达.结果 5组FAK蛋白表达量的差异有统计学意义(P<0.05),对照组与OLK上皮单纯增生组相比,差异无统计学意义(P>0.05),其余各组两两相比,差异均有统计学意义(P<0.05);5组PI指数的差异有统计学意义(P<0.05),对照组与OLK上皮单纯增生组相比,差异无统计学意义(P>0.05),其余各组两两相比,差异均有统计学意义(P<0.05);5组FAK mRNA表达量的差异无统计学意义(P>0.05),FAK蛋白表达与PI呈线性正相关(r=0.964,P<0.05).结论 FAK和PCNA在OLK上皮异常增生的患者中表达上调,二者的表达水平与OLK的癌变过程有关,可能作为评价OLK癌变过程的潜在标记物.     

Effect of chlorhexidine gel treatment on Streptococcus mutans population in human saliva and dental plaque

Abstract – The effect of topical application of a 1% chlorhexidine gel on the population of S.mutains in dental plaque and saliva was studied in five subjects highly infected with the organism. After treatment for 5 min daily for 14 d, S. mutans was not detected in three of the subjects and counts of 700 colony-forming units or less per ml of saliva were found in the other subjects. Reappearanceof S. mutans was slow and did not reach pretreatment level until 14 weeks or more after therapy. The proportion of S. saguis in plaque increased temporatrily after chlorhexidine treatment, whereas the population of lactobacilli was unaffected. These observations indicate that short-term use of chlorhexidine is of value in controlling oral infection of bumans by S. mutans.     

ANTIPLAQUE AND ANTIGINGIVITIS EFFECT OF LIPPIA SIDOIDES. A DOUBLE-BLIND CLINICAL STUDY IN HUMANS

Objectives:

The antiplaque and antigingivitis effect of Lippia Sidoides (LS) was evaluated in this in vivo investigation.

Material and Methods:

Twenty-three subjects participated in a cross-over, double-blind clinical study, using 21-day partial-mouth experimental model of gingivitis. A toothshield was constructed for each volunteer, avoiding the brushing of the 4 experimental posterior teeth in the lower left quadrant. The subjects were randomly assigned initially to use either the placebo gel (control group) or the test gel, containing 10% LS (test group).

Results:

The clinical results showed statistically significant differences for plaque index (PLI) (p<0.01) between days 0 and 21 in both groups, however only the control group showed statistically significant difference (p<0.01) for the bleeding (IB) and gingival (GI) index within the experimental period of 21 days. On day 21, the test group presented significantly better results than the control group with regard to the GI (p<0.05).

Conclusions:

The test gel containing 10% LS was effective in the control of gingivitis.