Determination of bactericidal activity of antibacterial monomer MDPB by a viability staining method

In this study, the bactericidal activity of antibacterial monomer MDPB (12-methacryloyloxydodecylpyridinium bromide) against Streptococcus mutans was tested by a rapid method for monitoring viability. To S. mutans culture containing fluorescence staining solution that distinguishes live from dead cells, MDPB was added at a concentration of 250, 100, 50, or 10 microg/ml. Bacterial cells were observed by fluorescence microscopy and the percentage of dead cells was calculated. After 10, 20, or 30 minutes' contact with MDPB, the live/dead ratio was measured by fluorometry and viable counts (CFU) determined by the conventional plating method. Viability staining revealed that MDPB exhibited significant bactericidal effects at 50 microg/ml or greater (ANOVA, Fisher's PLSD test), and complete killing of the cells at 250 microg/ml of MDPB was demonstrated in conjunction with a plating method. The staining method thus provided a sensitive means to determine loss of viability, and indicated the strong killing effects of MDPB on S. mutans.     

Blastogenic responsiveness of peripheral blood mononuclear cells from individuals with various forms of periodontitis and effects of treatment

Abstract Experiments were done to learn whether or not the blastogenic responsiveness of peripheral blood mononuclear cells (PBM) from 34 patients to mitogens and homogenates of a panel of periodontal bacteria differs significantly from that of cells from 16 normal individuals. Groups of control individuals and patients with juvenile (JP), rapidly progressive (RP) and adult periodontitis (AP) were formed. Blastogenic responsiveness was assessed after 72 and 120 h incubation by measuring the uptake of radioactive precursor into DNA. Bacterial preparations and mitogens used as stimulators included Bacteroides melaninogemcus (BMEL), Capnocytophaga (CAPNO), Fusobacterium nucleatum (FUSO), Actinomyces viscosus (AVIS), phytohemagglutinin (PHA), and pokeweed mitogen (PWM). When the data were calculated as Stimulation Index (E/C), responsiveness of cells from patients with AP and JP was enhanced relative to that of cells from normal control subjects, but the enhancement was not statistically significant. In contrast, responsiveness of cells from RP patients to FUSO and AVIS was significantly suppressed. Except in the case of AP cells activated with PHA, mitogenic responsiveness of all patient cells was significantly suppressed. When responsiveness was calculated as E minus C, these differences between patient and control cells disappeared except for suppression of the level of blastogenesis by AP and RP cells exposed to AVIS. After 120 h incubation, unstimulated cultures of AP cells incorporated significantly less, and RP cells significantly more, radioactivity than did unstimulated cultures from normal individuals indicating an abnormal autologous mixed lymphocyte reaction. Cells were harvested and tested from a group of AP patients before, during and following periodontal therapy. PBM responsiveness to horaogenates of CAPNO did not change significantly during therapy, but responsiveness to all of the other bacterial preparations including autologous plaque increased following initial therapy. Values for AVIS, FUSO, and PLAQ were statistically significant. Responsiveness to the bacterial preparations either remained at the enhanced levels or increased to even greater levels following completion of therapy, except in the case of autologous plaque, where the values had begun to return toward pretreatment levels. In addition, responsiveness to PWM and PHA dropped to about one-half the pretreatment values and responsiveness of unstimtilated cultures increased significantly to levels observed in cultures of ceils from normal donors.     

A survey of members of the American Academy of Pediatric Dentistry on their use of behavior management techniques

PURPOSE: The objective of this study was to survey members of the American Academy of Pediatric Dentistry (AAPD) regarding their use of behavior management techniques. METHODS: Surveys were mailed to 4,180 members, with a follow-up mailing to nonrespondents 2 months later. The survey contained items on demographic variables and use (current, past, and future) of communicative and pharmacologic techniques. Information was also obtained on informed consent, parental presence in the operatory, and parenting styles. RESULTS: Survey response was 66%. Communicative techniques are widely used, with the exception of the hand-over-mouth exercise (HOME). Immobilization for sedated and nonsedated children and pharmacologic techniques are used by a majority or near majority of respondents. Little change was reported in technique use over time, except that 50% of respondents indicated they use HOME less now than 5 years ago, and 24% plan to use it less over the next 2 to 3 years. Parental presence in the operatory appeared to be a common practice for some procedures and for children with special health care needs. The majority of respondents believed that parenting styles had changed in ways that adversely impacted children's behavior in the dental setting. CONCLUSIONS: Most practitioners have not changed their use of behavior management techniques in recent years, nor do they plan to change their use of them in the near future. HOME was the exception to these trends.     

Survey of behavior management teaching in predoctoral pediatric dentistry programs

PURPOSE: The purpose of this study was to survey directors of predoctoral pediatric dentistry programs regarding the teaching of behavior management techniques. METHODS: Surveys were mailed to all 56 dental schools in the United States. Follow-up mailings were sent to nonrespondents. The survey contained items on program demographics and the program's teaching of communicative and pharmacologic techniques. Information was also obtained on informed consent and parental presence in the operatory. RESULTS: Surveys were returned by 48 schools. Two schools declined to respond because they had not yet accepted or graduated students. The final response rate was 89%. The mean (+/-SD) percentage of total didactic time devoted to behavior management was 12% (+/-6). Communicative techniques were taught as "acceptable" by 96% to 100% of programs, with the exception of the hand-over-mouth exercise (HOME). HOME was taught as "unacceptable" by 62% of programs. Active and passive immobilization of sedated and nonsedated children was taught as "acceptable" by 69% to 85% of programs. Sixty-seven percent to 98% of programs taught that pharmacologic techniques (nitrous oxide, conscious sedation, general anesthesia) are "acceptable." There was little evidence that the teaching of behavior management techniques had changed over the previous 5 years, nor that they were likely to change in the near future. Parental presence in the operatory was common for some procedures, particularly among younger children. CONCLUSIONS: Predoctoral programs teach as acceptable communicative and pharmacologic management techniques, with the exception of HOME. Predoctoral program directors report they are not likely to increase the amount of curricular time devoted to behavior management in the near future.     

Assessing periodontal disease risk: a comparison of clinicians' assessment versus a computerized tool

BACKGROUND: The authors conducted a study to compare risk scores assigned by subjective expert clinician opinion with quantitative scores generated for the same subjects using the Periodontal Risk Calculator, or PRC. METHODS: The authors assembled a group of 107 subjects and performed standard periodontal examinations. The authors entered the resulting information into the PRC and calculated risk scores for two and four years, assuming no treatment would be performed. Using the same subject records, three groups of expert clinicians assigned risk scores for years 2 and 4. The authors analyzed the data to reveal the extent of interevaluator variation and the level of agreement between expert clinician scores and PRC scores. RESULTS: The extent of variation among scores assigned by individual expert clinicians was greater than the authors had expected. Expert clinicians consistently assigned more subjects to PRC risk group 2 and fewer to risk group 5 than did the PRC. The authors observed very high heterogeneity in the risk scores expert clinicians assigned to patients in each of the PRC-assigned groups. Thus, expert clinicians varied greatly in evaluating risk and, relative to the PRC, they appeared to underestimate periodontitis risk, especially for high-risk patients. CONCLUSIONS AND PRACTICE IMPLICATIONS: The authors' observations suggest that use of risk scores generated for individual patients by subjective expert clinician opinion about risk in periodontal clinical decision making could result in the misapplication of treatment for some patients and support the use of an objective tool such as the PRC. Use of the PRC over time may be expected to result in more uniform and accurate periodontal clinical decision making, improved oral health, reduction in the need for complex therapy and reduction in health care costs.     

Demonstration of Bacteroides intermedius in periapical tissue using indirect immunofluorescence microscopy

Abstract The presence of bacteria in periapical lesions of teeth with necrotic pulp has been demonstrated by microbiological sampling of periapical lesions during endodontic surgery. The purpose of this study was to confirm the presence of Bacteroides intermedius in a periapical granuloma using an indirect immunofluorescence technique. Histologic sections of a periapical granuloma were incubated with a rabbit antiserum to B. intermedius. After incubation with secondary antibody (fluorescein-conjugated goat anti-rabbit IgG), an intense fluorescent staining was observed in areas of the tissue sections. Control tissue sections that were incubated without the antibody remained unstained. The results obtained with the indirect immunofluorescence technique supported our cultural findings that microorganisms, e.g. B. intermedius, were present in the tissue of the periapical granuloma.     

Porphyromonas gingivalis mutY is involved in the repair of oxidative stress-induced DNA mispairing

The ability for DNA mismatch repair, after oxidative stress‐induced DNA damage, is critical for the persistence of Porphyromonas gingivalis in the inflammatory environment of the periodontal pocket. Our previous report demonstrated that, in contrast to other organisms, the repair of oxidative stress‐induced DNA damage involving 8‐oxo‐7,8‐dihydroguanine (8‐oxoG) may occur by a yet‐to‐be described mechanism in P. gingivalis. 8‐oxoG does not block DNA replication; rather, it mispairs with adenine, which can be repaired by the MutY glycosylase. To determine the function of the P. gingivalis MutY homologue in DNA repair, it was insertionally inactivated using the ermF‐ermAM antibiotic cassette and used to create a mutY‐deficient mutant (FLL147) by allelic exchange mutagenesis. FLL147 had an increased rate of spontaneous mutation and was more sensitive to hydrogen peroxide compared with the wild‐type W83 strain. DNA oligomers containing a site‐specific 8‐oxoG:A mispair was repaired similarly in both the P. gingivalis mutY‐defective mutant and wild‐type strains. The P. gingivalis mutY homologue was shown to complement the mutY mutation in Escherichia coli. In a gel mobility shift assay, the purified recombinant MutY is able to bind an oligo containing an 8‐oxoG:A mispair. Taken together, MutY may play the expected role in oxidative stress resistance in P. gingivalis. However, there may exist other redundant mechanism(s) for the removal of 8‐oxoG:A mismatch in this organism.     

Short-term effects of glucose and sucrose on cognitive performance and mood in elderly people

In this study we determined the short-term effects of a glucose drink and a sucrose drink compared to a placebo on cognitive performance and mood in elderly people with subjective, mild memory complaints using a randomized crossover study design. In total, 43 nondiabetic older adults with self-reported memory complaints were included. Drinks consisted of 250 ml with dissolved glucose (50 g), sucrose (100 g), or a mixture of artificial sweeteners (placebo). Multiple neuropsychological tests were performed and were combined by means of z scores into four cognitive domains: episodic memory, working memory, attention and information (processing speed), and executive functioning. Mood was assessed with the short Profile of Mood Status (s-POMS) questionnaire. Blood glucose concentrations were measured at five time points to divide participants into those with a better or poorer blood glucose recovery. Performance on the domain of attention and information processing speed was significantly better after consuming the sucrose drink (domain score of 0.06, SD = 0.91) than after the placebo drink (–0.08, SD = 0.92, p = .04). Sucrose had no effect on the other three domains, and glucose had no effect on any of the domains compared to the placebo. When dividing participants into poorer or better glucose recoverers, the beneficial effect of sucrose on attention and information processing speed was only seen in participants with a poorer recovery. After sucrose consumption, depressive feelings and tension were slightly higher than after the placebo. To conclude, 100 g sucrose, but not 50 g glucose, optimized attention and information processing speed in the short term in this study in elderly people with subjective, mild memory complaints.