Sucrose-induced ecological response of experimental dental plaques from caries-free and caries-susceptible Human volunteers.

Microbial succession, experimental cariogenicity, and sucrose metabolism were examined in dental plaques which developed on sterile bovine enamel inserts in acrylic palatal appliances. The appliances were worn for a period of 14 days by 10 caries-free and 10 caries-susceptible human volunteers. Three of six enamel inserts on each appliance were exposed extraorally to 10% sucrose in 0.85% saline six times a day, and three were exposed simultaneously to 0.85% saline as a control environment. The responses of the plaques to the high-sucrose environment in both caries status populations were compared. In all plaques, exposure to 10% sucrose stimulated the succession of Veillonella spp., Lactobacillus spp., Streptococcus salivarius, and, to a lesser extent, Streptococcus mutans and a decline in levels of Streptococcus sanguis, Neisseria spp., and gram-negative anaerobic rods. Plaques from caries-free mouths, in contrast to those from caries-susceptible mouths, harbored higher levels of Veillonella spp., gram-negative anaerobic rods, and Neisseria spp. and lower levels of Lactobacillus spp. Sucrose-exposed plaques from caries-free mouths also induced less enamel microhardness changes and formed less lactic acid from [14C]sucrose during a 60-min incubation at 37 degrees C than did comparable plaques from caries-susceptible mouths. The experiments revealed consistent differences in the ecological response to a cariogenic substrate environment in plaques from the two populations, with plaques from caries-free subjects exhibiting less cariogenic potential than those from caries-susceptible subjects.     

An in vivo replica study of microbial colonization in "rapid" and "slow" dental plaque formers

The aim of the present study was to investigate the morphological features of supragingival plaque development in "rapid" and "slow" plaque formers using the replica technique. Forty-nine healthy volunteers were screened for their plaque formation rate after 3 days of oral hygiene abstinence using the plaque index (PI). Five subjects with the highest mean PI and six with the lowest mean PI were selected as "rapid" and "slow" plaque formers, respectively. After a series of thorough prophylaxis and oral hygiene instruction, all subjects went through a 14-day period of no oral hygiene to allow undisturbed plaque formation. Light body silicone elastomeric impressions were taken for the upper right central incisor of each subject on day-0, 1, 3, 7, and 14. Positive replicas were then poured from the impressions using epoxy resin and observed under a scanning electron microscope. A more complex supragingival plaque structure was seen in the day-1 and day-3 replicas of the "rapid" group compared to the "slow" group. From day-7 to day-14, during the maturation period of supragingival plaque, no discernible differences were noted between the two groups. Quantitatively, the percentage of plaque coverage on the tooth surfaces was higher in the "rapid" group than in the "slow" group in day-1 and day-3 replicas. These observations indicate that the morphological and topographical features of supragingival plaque in "slow" and "rapid" plaque formers differ, especially in the early developmental phase.     

不同材料烤瓷冠在后牙种植修复中的对比

背景：种植体上部结构牙冠材料的选择十分重要,其临床修复效果直接影响到种植体的寿命和患者的牙周健康状况。 目的：比较Lava氧化锆全瓷、金铂合金烤瓷与银钯合金烤瓷冠在后牙单颗缺失口腔种植修复中的临床效果。 方法：选择60例120颗第一磨牙缺失病例,完成单颗牙缺失种植牙修复治疗,上部结构修复牙冠材料分别为Lava氧化锆全瓷冠、金铂合金烤瓷冠与银钯合金烤瓷冠,每种材料40颗,比较3种修复体的临床修复效果。 结果与结论：通过6-48个月的随访发现,Lava氧化锆全瓷冠组和金铂合金烤瓷冠组的牙龈边缘着色、龈缘密合度、修复体颜色优于银钯合金烤瓷冠组,Lava氧化锆全瓷冠组的牙龈边缘着色和修复体颜色优于金铂合金烤瓷冠组,金铂合金烤瓷冠组的龈缘密合度优于Lava氧化锆全瓷冠组;银钯合金烤瓷冠抗折程度最强,最具临床优越性,但其牙龈指数最高,牙龈健康程度最差,菌斑形成速度最快、程度最重。由此可见,在种植修复完成后需要选择较为适合的冠部修复体进行种植修复,Lava氧化锆全瓷冠具有卓越的生物相容性,而金铂合金烤瓷冠在边缘密合性方面更具优势,此两种修复体在临床治疗中具有一定的优势。中国组织工程研究杂志出版内容重点：生物材料;骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性;组织工程全文链接：     

Molecular identification and antifungal susceptibility testing of Candida species isolated from dental plaques

Objective

The aim of the present study was to provide insight into the prevalence and susceptibility profiles of Candida species isolated from the dental plaque of Iranian immunocompetent patients. As a biofilm, Candida species are responsible for several disorders common to the oral cavity including gingivitis, dental caries, periodontitis, and the less common severe systemic infections specifically in immunosuppressed individuals.

Association between commensal bacteria and opportunistic pathogens in the dental plaque of elderly individuals

Opportunistic infections in the oral cavity of the elderly may increase the incidence of systemic disease. The objective of this study was to investigate the differences in the oral bacterial flora between dependent elderly (inpatients) and independent elderly (community-dwelling residents). After multiple variables were taken into account, inpatients had significantly lower detection rates than community-dwelling residents for alpha-streptococci (p < 0.001) and Neisseria (p 0.004), and higher detection rates for Pseudomonas aeruginosa (p 0.024), methicillin-resistant Staphylococcus aureus (MRSA) (p 0.011) and Actinomyces spp. (p 0.005). Among inpatients, the requirement for a high degree of care was related negatively to detection of alpha-streptococci, but was related significantly to detection of P. aeruginosa (p 0.018) or MRSA (p 0.004). Tube-fed inpatients had a significantly lower detection rate for alpha-streptococci (p 0.041) and a higher detection rate for P. aeruginosa (p 0.004) than those who did not require tube feeding. Inpatients with a history of antibiotic use had a significantly lower detection rate for alpha-streptococci (p 0.049) and a higher detection rate for MRSA (p 0.007) than those without a history of antibiotic use. The detection rates for P. aeruginosa or MRSA in inpatients without alpha-streptococci were higher than in inpatients with alpha-streptococci after controlling for age and gender (P. aeruginosa, p 0.006; MRSA, p 0.001). Overall, detection of alpha-streptococci had an inverse correlation with the detection of P. aeruginosa and MRSA in the oral cavity and is likely to be an indicator of pathogenic bacterial infection.     

Personality characteristics versus medical and dental experiences of dentally anxious children

There is some conflicting evidence in the literature regarding whether dental phobia is a circumscribed fear or an instance of general fearfulness. In an attempt to tease out the effect of general fearfulness from that of aversive dental experiences, mothers of a group of 12 year-old children of both sexes were interviewed regarding their child's temperament and early dental and medical experiences. The results indicated that previous aversive dental experiences were more closely related to dental anxiety than was general fearfulness. Dentally anxious boys appeared to have been influenced by external factors, while the dentally anxious girls' influences appeared to be internal ones. Finally, early behavioral signs of distress in the operatory were predictive of later dental anxiety.     

Psychological and behavioral factors associated with dental anxiety in children

This study of the relationship between dental anxiety and psychological and behavioral variables suggests that the most important factor in explaining the variance in children's perceived dental anxiety is their level of general anxiety. The negative relationship found among the frequency of dental visits, deciduous diseased, missing, and filled teeth (dmft), and dental anxiety implies that dental anxiety does not develop through simple exposure to dental settings. Perceived locus of control and perceived health vulnerability did not appear to be associated in any significant way with dental anxiety. The results indicate that dental anxiety may reflect a more general class of anxiety behaviors, rather than fears learned in response to a specific situation.     

Confocal observation of senile plaques in Alzheimer's disease: Senile plaque morphology and relationship between senile plaques and astrocytes

Senile plaques In the brains of Alzheimer's disease (AD) were examined by confocal laser scanning microscopy (CLSM) with the following three findings. First, in sections stained with Congo red, the serial CLSM images of optical sections clearly revealed that a classic plaque is composed of a plaque core and a corona. Radially arranged process-like structures, corresponding to bundles of amyloid fibrils, formed amyloid cores and stronger signals were detected in the center of some cores. Second, in sections stained with Congo red and anti-gllal fibrillary acidic protein (GFAP), reactive astrocytes were found around the senile plaques and many astrocytlc processes surrounded the plaque cores and some processes had penetrated into them. Third, three-dimensional reconstruction on classic plaque revealed that the surface of classic plaque showed a 'coral-like' appearance.     

A longitudinal study of the contribution of dental experience to dental anxiety in children between 9 and 12 years of age

Dental records of a group of children of both sexes were examined systematically over a period of 3 years to determine if the quantity and quality of their dental experience would be associated with increases in dental anxiety. The study was a follow-up of an earlier cross-sectional survey in which older children had demonstrated increases in dental anxiety with age. According to the evidence obtained from their dental records, the children were divided into four groups depending on their patterns of attendance (regular/irregular) and whether or not they had received invasive treatment. The results indicated that children who did not receive invasive treatment during the period under scrutiny were significantly more anxious than those who had. On the other hand, the dental anxiety of children who attended regularly and received invasive treatment did not change significantly. This applied to boys and girls alike.