Distribution of Porphyromonas gingivalis and Treponema denticola in human subgingival plaque at different periodontal pocket depths examined by immunohistochemical methods

Localization of Porphyromonas gingivalis and Treponema denticola in different areas of subgingival plaque from advanced adult periodontitis patients was studied immunohistochemically using sensitive immunogold-silver staining and immunoelectron microscopy. Fourteen periodontally diseased teeth were extracted without damaging the subgingival plaque, fixed, and embedded. The subgingival plaque samples were sectioned according to four different pocket depths (0–2 mm, 2–4 mm, 4–6 mm and ≤6 mm). Serial thin sections were stained using specific antisera to P. gingivalis or T. denticola and then with secondary antibody labelled with colloidal-gold. Cells of both P. gingivalis and T. denticola were predominantly found in subgingival plaque located at depths of more than 4 mm in periodontal pockets. T. denticola cells were found in the surface layers of subgingival plaque, and P. gingivalis were predominant beneath them. However, in the deeper subgingival plaque, the coexistence of P. gingivalis and T. denticola was observed. The present findings suggest that P. gingivalis and T. denticola play important roles in the pathogenicity of periodontal disease and provide the useful information for elucidating the pattern of colonization of microorganisms in the periodontal pocket.     

The influence of 30-day-old Streptococcus mutans biofilm on the surface of esthetic restorative materials--an in vitro study

OBJECTIVE: To evaluate the effects of Streptococcus mutans biofilm/restorative materials interaction on surface roughness, hardness and morphology of materials tested. METHODS: Empress 2 (E2), Filtek Supreme (FS), Vitremer (V) and Ketac Molar Easymix (KM) were tested. Twenty-five disks of each material were made and divided into three storage groups: (1) 100% relative humidity (n=5); (2) growth medium (BHI and 1% sucrose) (n=5); (3) S. mutans biofilm-growth medium (n=15). Before storage, hardness measurements were immediately obtained from group 1 specimens. After 30 days of storage, the specimens were cleaned in order to obtain the surface roughness and hardness values, besides morphology analysis by scanning electron microscopy. RESULTS: The surface roughness and hardness values obtained from E2 and FS specimens did not present statistically significant differences among the groups 1, 2 and 3 and between immediate and 30-day-old specimens of each material. However, group 3 specimens of V and KM showed statistically significant higher surface roughness means than other groups. Group 1 specimens of V and KM also showed higher hardness values than the immediate values. Group 3 specimens of V presented decreased hardness values compared with other groups. The scanning electron micrographs showed an increase in surface degradation from group 1 to group 3 for FS, V and KM. CONCLUSIONS: Thirty-day-old biofilm promotes a negative effect on the surface morphology of FS, V and KM, on the surface roughness of V and KM and on the hardness of V.     

Effects of plaque control on the patency and occlusion of dentine tubules in situ

To elucidate the nature of dentine hypersensitivity, the effects of plaque control on the patency and occlusion of dentinal tubules were investigated systematically in situ using human dentine slabs embedded in partial dentures. The dentine slabs were divided into three groups. In group I, the dentine slabs were kept in an oral cavity without plaque control. In group II, plaque was removed mechanically by brushing. Plaque control was carried out chemically using chlorhexidine in group III. After being kept in the oral cavities for 1, 2 and 3 weeks, the slabs were removed from the partial denture, followed by SEM observation to determine the morphological changes of the dentinal tubules. When no attempt was made to remove plaque, the diameter of tubule orifices increased to 390% of the original values within 3 weeks. In contrast, dentinal tubules were found to be occluded, i.e. the tubule orifices became <20% of the original value within 1 week when plaque control efforts were made, using either method of plaque control. We conclude that plaque control plays one of the key roles in the patency versus occlusion of dentinal tubules, and thus in the aetiology and natural reparative process of dentine hypersensitivity.     

系统观在龋病病因研究中的体现

龋病病因是口腔医学爱们多年来的探索重点之一,20世纪．60,70年代提出的“四联因素”学说已被逐步证实,并逐渐得到公认,因为它是在系统观点的指导下形成的,本文就龋病病因学理论中的系统观点进行了较为详细的分析与阐释。     

Plaque and gingivitis in the elderly: a randomized, single-blind clinical trial on the outcome of intensified mechanical or antibacterial oral hygiene measures

OBJECTIVES: To study the outcome of intensified mechanical oral hygiene compared with the effect of an adjunctive antibacterial mouth rinse on plaque and gingivitis in elderly people. MATERIAL AND METHODS: In a randomized, single-blind, 6-month controlled clinical study, 106 subjects, 55 years or older, were divided into four groups: (I) Participants were instructed on improved mechanical oral hygiene, including interdental hygiene; (II) subjects used an antibacterial mouth rinse containing amine and stannous fluoride in addition to their usual oral hygiene practices; (III) both intensive mechanical and antibacterial measures were combined; and (IV) a control group with no specific regimen. Gingivitis and plaque were examined. RESULTS: After 6 months, both plaque and gingivitis scores were significantly lower than at baseline in all groups. Reductions in gingivitis differed significantly between the control group and all other groups but not between the three intervention groups. Only groups with improved mechanical oral hygiene showed significant improvements in plaque scores compared with control. CONCLUSIONS: Intensive mechanical oral hygiene resulted in greater plaque reduction than the combination of an antibacterial rinse and usual oral hygiene procedures. Gingivitis was reduced by both intensive oral hygiene and use of the amine/stannous fluoride rinse. Combining intensive mechanical oral hygiene with the antibacterial rinse did not result in further gingivitis reduction.     

Absence of Helicobacter pylori in the oral cavity of 10 non‐dyspeptic subjects demonstrated by real‐time polymerase chain reaction

Helicobacter pylori plays a significant role in gastric disease. However, the presence of this bacterium in the oral cavity remains controversial. The aim of the present study was to detect and quantify H. pylori in 29 different sites of the oral cavity in non‐dyspeptic subjects by means of real‐time polymerase chain reactions (PCR). Ten subjects without gastric symptoms were studied. Samples from unstimulated saliva, three sites of the tongue, oral mucosa, and 12 sites of both supragingival and subgingival plaque were collected from each subject. DNA was extracted from the oral samples and analysed for the presence of H. pylori by real‐time PCR (LightCycler^®) using JW23/22 primers which targeted the 16S rRNA gene. DNA from H. pylori DSM 4867 was used as a positive control. Amplification efficiency for the LightCycler^® 2.0 runs ranged from 1.8 to 2.4. Melting curve analysis identified all the positive control capillaries, which contained H. pylori reference DNA, as a single and narrow peak at a melting temperature between 84.5 and 84.9°C. All the negative control capillaries with no template control and the 29 oral samples from each subject showed either no melting peaks or broad melting peaks below 80°C, which were considered as primer dimers. Therefore, H. pylori was not detected from any of the 290 oral samples. As a conclusion, H. pylori seems not to be permanently present in the oral cavity of a non‐dyspeptic population.     

儿童使用声波震动牙刷清除牙菌斑的效果观察

目的:观察儿童使用声波震动牙刷清洁牙及控制菌斑的效果。方法:选择年龄6～7岁的儿童50例,实验组使用声波震动牙刷,对照组使用儿童保健牙刷。采用菌斑染色法记录刷牙前后的菌斑牙面数及菌斑指数(PLI),采用SPSS10.0统计软件包对相关组间数据进行t检验与χ2检验。结果:实验组菌斑清除率为70.22%,对照组为39.08%,声波震动牙刷去除舌面、近中颊面菌斑的能力是手动刷牙的2倍。刷牙前后菌斑指数和菌斑清除率在2组间有高度显著性差异(P<0.001)。结论:声波震动牙刷能有效帮助儿童清除牙面菌斑,是儿童口腔护理的有效工具。     

Effect of vitamin E on periodontitis: Evidence and proposed mechanisms of action

BackgroundPeriodontitis is a noncommunicable inflammatory disease of the soft tissue and bone surrounding the teeth in the jaw, which affects susceptible individuals with poor oral hygiene. A growing interest has been seen in the use of dietary supplements and natural products for the treatment and prevention of periodontitis. Vitamin E consists of two major groups, namely tocopherols and tocotrienols, which are botanical lipophilic compounds with excellent anti-inflammatory and antioxidant properties.HighlightThis review aimed to summarize the preclinical and clinical findings on the effects of vitamin E on periodontitis. The current literature suggests that vitamin E could improve the periodontal status by correcting redox status imbalance, reducing inflammatory responses, and promoting wound healing, thus highlighting the potential of vitamin E in the management of periodontitis.ConclusionDirect evidence for the use of vitamin E supplementation or treatment of periodontitis in humans is still limited. More well-designed and controlled studies are required to ascertain its effectiveness.     

Detection frequency of periodontitis-associated bacteria by polymerase chain reaction in subgingival and supragingival plaque of periodontitis and healthy subjects

The aim of this study was to compare the detection frequencies of 25 bacterial species in subgingival and supragingival plaque of 18 untreated periodontitis subjects and 12 periodontally healthy subjects. Genomic DNA was extracted from subgingival and supragingival plaque samples, and bacterial detection was performed by polymerase chain reaction of the 16S rRNA genes. Fourteen bacteria showed no relationship with periodontitis, and 11 of these 14 species were frequently detected (≥50%) in subgingival plaque in both periodontitis and healthy subjects. Nine bacteria such as Eubacterium saphenum, Prevotella intermedia, and Treponema denticola seemed to be related to periodontitis; their detection frequencies in subgingival plaque samples were higher in periodontitis than in healthy subjects, but these differences were not statistically significant by multiple comparisons (0.002≤ P< 0.05). Two species ( Mogibacterium timidum and Porphyromonas gingivalis ) were detected significantly more frequently in subgingival plaque of periodontitis subjects than of healthy subjects ( P< 0.002), with P. gingivalis being detected only in periodontitis subjects, suggesting that these two species are closely related to periodontitis. There were no significant differences in the detection frequencies of the 25 bacteria between subgingival and supragingival plaque, suggesting that the bacterial flora of supragingival plaque reflects that of subgingival plaque.