Antimicrobial effect of probiotic bacteriocins on Streptococcus mutans biofilm in a dynamic oral flow chamber model - an in vitro study.

Aim: To determine the antimicrobial activity of the bacteriocin-producing probiotic strains Streptococcus salivarius K12 and Streptococcus salivarius M18 alone or in combination against caries-associated Streptococcus mutans. Methods: Antimicrobial activity of S. salivarius K12 and/or S. salivarius M18 against S. mutans ATCC 25175 growth and biofilm formation on hydroxyapatite (HA) discs was determined in a flow chamber model by recording the colony forming units (CFU/ml) after 48 h of co-cultivation. The biofilm was analyzed by scanning electron microscopy (SEM) and by confocal laser scanning microscopy (CLSM). Additionally, the simultaneous antagonism assay was used to assess the inhibitory effect of S. salivarius K12 and/or S. salivarius M18 against S. mutans ATCC 25175 and 21 clinical isolates of S. mutans. Results: Co-cultivation of S. mutans and S. salivarius K12 and/or S. salivarius M18 led to the inhibition of S. mutans viability, thereby, preventing its biofilm formation on HA discs. Furthermore, S. salivarius K12 and S. salivarius M18 exhibited antimicrobial activity against most clinical isolates of S. mutans. Conclusion: The in vitro flow chamber system used in this study allows the simulation of time-dependent administration of S. salivarius probiotic strains, either alone or in combination, to investigate the prevention of S. mutans biofilm formation in a standardized model.

Antibiotic Resistance among Fusobacterium, Capnocytophaga, and Leptotrichia Species of the Oral Cavity.

PURPOSE: Antibiotics play an important role in treating periodontal diseases. Due to the effectiveness of antibiotic therapies, their usage in dentistry has significantly increased. The aim of this study focused on the in-vitro susceptibility of different gram-negative oral bacteria species - which are associated with periodontal diseases (Fusobacterium spp., Capnocytophaga spp. and Leptotrichia buccalis) and have different geographical origins (Asia and Europe) - against antimicrobials that are clinically relevant in dental therapy. MATERIALS AND METHODS: A total of 45 strains were tested (29 Fusobacterium spp., 13 Capnocytophaga spp. and 3 L. buccalis) that were either isolated from Chinese patients or were obtained from different strain collections. Their antimicrobial susceptibility to the antimicrobial agents benzylpenicillin, amoxicillin, amoxicillin-clavulanic acid, ciprofloxacin, moxifloxacin, clindamycin, doxycycline, tetracycline and metronidazole was tested using the E-Test. Strains with particular resistance to penicillin, clindamycin and metronidazole were further analysed for resistance genes. RESULTS: All tested bacterial isolates were sensitive to amoxicillin, amoxicillin-clavulanic acid, doxycycline and tetracycline, but showed variable sensitivity towards other antibiotics such as benzylpenicillin, ciprofloxacin, moxifloxacin, clindamycin and metronidazole. CONCLUSION: The results of the present study suggest that certain periodontal disease-related bacterial strains can be resistant towards antimicrobial agents commonly used in adjuvant periodontal therapy.

Prevalence of and factors associated with molar-incisor hypomineralisation in schoolchildren in the canton of Basel-Landschaft, Switzerland.

OBJECTIVES: As prevalence of molar-incisor hypomineralisation varies considerably in different countries and regions, the aim of this study was to obtain representative epidemiological data for schoolchildren living in the canton of Basel-Landschaft, Switzerland. MATERIAL AND METHODS: A representative population of schoolchildren of three different age groups, i.e. 1st grade (mean age: 7.4 years), 6th grade (mean age: 12.6 years), and 9th grade (mean age: 15.7 years) visiting compulsory schools in the canton of Basel-Landschaft, Switzerland, was examined. The presence or absence of molar-incisor hypomineralisation at time of examination was recorded as well as potential influencing factors such as age group, gender, nationality, or the children's place of residence. RESULTS: A total of 1252 schoolchildren could be included. On average, the prevalence of MIH in the study population was 14.8%. No statistically significant differences were found for nationality, gender, or place of residence. Although not statistically significant, children from the youngest age group had the highest while children from the oldest age group had the lowest MIH prevalence. CONCLUSION: With a mean value of 14.8%, MIH prevalence among schoolchildren living in the canton of Basel-Landschaft, Switzerland, is comparable to mean values recorded globally. CLINICAL RELEVANCE: This study represents the first study on MIH prevalence in Switzerland and also provides further evidence on potential influencing factors.

Interdental biofilm reduction and composition after use of an activated and inactivated side-to-side toothbrush - a proof-of-principle clinical study.

OBJECTIVES: To evaluate interdental biofilm reduction and composition after powered toothbrushing with a side-to-side (sonic) toothbrush compared to manual toothbrushing following single brushing exercises in periodontally healthy young adults. MATERIALS AND METHODS: All participants brushed with a side-to-side toothbrush without toothpaste in four different modes: toothbrush (a) inactivated without instruction (OFF-NI), (b) activated without instruction (ON-NI), (c) inactivated with instruction (OFF-I), and (d) activated with instruction (ON-I) at consecutive visits (single brushing exercises). Before and after brushing, the Approximal Plaque Index (API) was assessed at three interdental spaces and plaque samples were taken from two interdental sites. Biofilm reduction and composition were analyzed microbiologically by total bacterial load and 16S rRNA sequencing. RESULTS: Thirty participants (age: 22.9 ± 2.5 years) completed the study. Most participants showed no or incomplete plaque removal assessed by API following single brushing exercises, while the frequency of API reduction was higher after ON-NI compared to OFF-I (p = 0.023). Irrespective of the brushing mode, a significant reduction of total bacterial load was detected with lower bacterial counts after OFF-NI compared to ON-NI (p = 0.008) and ON-I (p = 0.007). Biofilm composition showed slight changes in the relative abundances of bacterial taxa, regardless of the brushing mode. CONCLUSIONS: Manual and powered toothbrushing with a side-to-side toothbrush, with and without instruction, showed incomplete interdental biofilm removal in periodontally healthy young adults following single brushing exercises. CLINICAL RELEVANCE: Data has to be validated in further studies on other groups, however, in periodontally healthy young adults, additional devices seem to be necessary for sufficient interdental cleaning.

Caries status of first-born child is a predictor for caries experience in younger siblings.

OBJECTIVES: This study analysed if children of families in need of dental interventions can be identified by using the caries status of the first-born child as a predictor for caries in younger siblings of the same family. MATERIAL AND METHODS: All children aged 4 to 15 years, i.e. 13,596 children, visiting a compulsory school in the canton of Basel-Stadt, Switzerland, during the school year 2017/2018 were analysed. Total caries experience and untreated carious lesions at time of examination were recorded as well as a subset of socioeconomic factors such as gender, age, nationality, birth order and the family's place of residence. RESULTS: A total of 6738 schoolchildren who had at least one sibling of school age could be included. Differences in caries experience and the presence of active carious lesions were found for age, nationality and place of residence but not for gender or birth order. Younger siblings had odds of having a history of caries 3.7 times higher (95% confidence interval: 3.0-4.4) and odds of having active carious lesions 3.5 times higher (95% confidence interval: 2.6-4.7) if the eldest child in the family already had caries. CONCLUSION: Caries could be shown to be family-dependent. Younger siblings had a more than three-fold higher risk for caries if the first-born child already had carious lesions. CLINICAL RELEVANCE: Based on these results, the caries status of the first-born child could be used as a potential indicator to detect vulnerable families and to initiate targeted preventive measures.

Awareness of vaccine-preventable diseases and self-reported immune status of Swiss dental healthcare workers.

INTRODUCTION: Dental healthcare workers are exposed to various infectious agents that may present an occupational risk. Although vaccinations rank among the most cost-effective health measures, vaccine hesitancy is present among healthcare workers. METHODS: A structured anonymous questionnaire was completed by 1111 dental healthcare workers - dentists, dental hygienists, prophylaxis assistants, dental assistants, dental technicians, and dental students. Demographic data and immunisation status, either by vaccination or by immunity after disease, were collected. Additionally, employers and employees were asked about their current workplace vaccination policy, including questions about information provided on the risk of hepatitis B (HBV) infection, whether HBV vaccination was compulsory and who paid for compulsory vaccinations. RESULTS: The overall response rate was 55.7%. Approximately half of the participants were dentists; only 17 technicians completed the questionnaire. The most common immunisation was for HBV (94.7% of participants). Only 19.2% of participants reported immunisation against human papillomavirus. Uncertainty over immunisation status was highest for Haemophilus influenzae type B (46.7%). Only a minority of participants (17.4%) received a yearly vaccination against seasonal influenza, whereas two-thirds never get vaccinated. The participants' level of awareness related to the seven general vaccinations (HBV, influenza, measles, mumps, rubella, varicella, and tetanus) was medium to high, whereas their level of awareness related to vaccinations against HBV and influenza was medium. Half of the employees stated that they were informed about the risk of HBV at their current workplace and over three-quarters of employers indicated that they provided such information to their employees. Compulsory HBV vaccination was implemented at approximately half of the dental practices. CONCLUSION: The Swiss dental healthcare workers participating in this study had a medium level of awareness towards vaccinations. Almost all participants were vaccinated against HBV, but they were particularly hesitant about the seasonal influenza vaccination. As a considerable number of participants was unaware of their immunisation status, more comprehensive information on infectious diseases, vaccination and prevention is essential.

Cariogenic Biofilms and Caries from Birth to Old Age.

Caries is a complex microbial disease characterized by a multifactorial etiology. The disease is driven by cariogenic microbiota that metabolize dietary carbohydrates into acids, creating prolonged periods of low pH on the biofilm surrounding the teeth, which will result in loss of calcium from the teeth leading to carious lesions. Caries remains a major public health problem globally, ranking first for the decay of permanent teeth (2.3 billion people) and 12th for deciduous teeth (560 million children) according to the Global Burden of Disease study by the WHO in 2015. Different factors play a role in the development of the disease: (i) individual factors such as tooth morphology, saliva, and the oral microbiome, (ii) behavioral factors such as frequency and amount of fermentable carbohydrates in the host's diet and overall oral hygiene, and (iii) socioeconomic status and host genetics as well as modifying factors such as fluoride. Various models exist which explain the transition from a health-compatible oral microbiota to a cariogenic microbiota. Longitudinal studies may increase our knowledge of the oral microbial compositions in different age groups by analyzing the temporal sequence leading to carious lesions. Understanding the factors which control microbial colonization early in life as well as the keystone species that should be present or absent may provide us with strategies for the acquisition and maintenance of a health-promoting oral microbiome. Thus, the importance lies in understanding caries etiology to improve strategies for diagnosis, risk assessment, prevention, and (operative) treatment.

Tolerance and Persister Formation in Oral Streptococci.

The aim of this study was to analyze the potential influence of long-term exposure in subinhibitory concentrations of chlorhexidine on the emergence of tolerant and/or persistent cells in oral streptococci. The two oral streptococcal isolates S. mutans ATCC25175 and S. sobrinus ATCC33402 were incubated, after long-term subinhibitory exposure to chlorhexidine, in liquid growth media containing high concentrations of chlorhexidine. A distinct subpopulation of more chlorhexidine-tolerant cells could be detected in streptococci that had been previously exposed to subinhibitory concentrations of chlorhexidine but not in the control strains. These more biocide-tolerant and persisting microbial subpopulations might also arise in vivo. Therefore, the rational and proper use of antimicrobials in dentistry, especially when used over a long period of time, is crucial.

Antibiotic Susceptibility Patterns of Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis Strains from Different Decades.

The aim of this study was to determine the antibiotic susceptibility patterns of 57 Aggregatibacter actinomycetemcomitans and 56 Porphyromonas gingivalis strains isolated from subgingival biofilm samples of periodontitis patients in Switzerland from 1980 to 2017. The minimal inhibitory concentrations (MIC) of the most commonly used antibiotics in periodontal therapy (amoxicillin, metronidazole, azithromycin, and doxycycline) or in severe body infections (amoxicillin/clavulanic acid, clindamycin, ertapenem, and moxifloxacin) were determined. Furthermore, all the strains were screened for beta-lactamase activity and the presence of selected resistance genes (cfxA, ermF, and tetQ). Overall, there was no significant increase in MIC values over the 37­year period. Two of the most recent P. gingivalis isolates yielded the highest MIC values. The first isolate was ermF-positive with MIC values >8 µg/mL, 2 µg/mL, and 0.25 µg/mL for clindamycin, azithromycin, and moxifloxacin, respectively. The second isolate showed a high MIC value of 4 µg/mL for moxifloxacin, which was associated with a confirmed single-point mutation in the quinolone resistance-determining region (QRDR) of the gyrA gene. Although there was no significant increase in the antibiotic resistance among the oral bacterial isolates tested, the detection of resistant P. gingivalis isolates underlines the need to optimize the antibiotic therapeutic protocols in dentistry.

Surface microbial contamination in a dental department. A 10-year retrospective analysis

Health care-associated infections may not only occur in a hospital setting, but also in dental clinics. Insufficient environmental decontamination could be one of the risk factors. In this retrospective study, we documented and analyzed the results of surface microbial contamination in a dental university-based department over an observation period of ten years. It was the aim of this investigation to identify general tendencies and potentially problematic sites on a long-term basis allowing suggestions for further improvement. Surface microbial contamination in the Department of Reconstructive Dentistry at the University Center for Dental Medicine in Basel, Switzerland, was evaluated on a regular basis using contact plates. Data gained between January 2007 and December 2016 was collected and summarized for statistical analysis. Although the overall surface microbial contamination was relatively low during the observation period, significant differences depending on localization and test sites were detected. Certain sites, such as the handle of the dentist's chair and computer surfaces, remained problematic. Continuous monitoring of surface microbial contamination can help to improve the hygiene level in a dental set-up. Further improvement might be achieved by avoiding hand-touch handles whenever possible and by relying on flat and easy-to-clean surfaces within the reach of the bacterial aerosol. However, during interventions that may pose a higher risk for the patient, additional measures should be taken by working under almost sterile conditions and by avoiding direct hand contact with problematic sites.

Caries experience in 7-, 12-, and 15-year-old schoolchildren in the canton of Basel-Landschaft, Switzerland, from 1992 to 2011.

OBJECTIVES: To investigate the changes in caries experience and prevalence among schoolchildren of the canton of Basel-Landschaft, Switzerland, over the course of 20 years. METHODS: A random sample of either schoolchildren aged 7, 12, and 15 years (in 1992) or aged 12 and 15 years (in 1997) or their respective school classes (2001, 2006 and 2011) was selected so that approximately 10% of schoolchildren could be examined. The children's dmft and DMFT scores were determined according to the WHO methodology and analyzed using cluster-adjusted ordinary multiple linear regression modeling. RESULTS: For all age groups, the respective dmft/DMFT values decreased steadily from 1992 to 2006 but increased again in 2011. However, the observed differences were not statistically significant over the examination years from 2001 to 2011. Schoolchildren with a migrant background had approximately two- to threefold higher dmft/DMFT values. CONCLUSIONS: In the years from 1992 to 2001, a steady decline in caries was observed in all age groups of schoolchildren examined in the canton of Basel-Landschaft. However, in the subsequent 10 years, this decline has leveled off. The mean dmft/DMFT values are comparable to those in other parts of Switzerland. Migrants are a caries-risk group; the mean dmft/DMFT values were higher in schoolchildren with a migrant background than in the comparable Swiss children.

Development of resistance of mutans streptococci and Porphyromonas gingivalis to chlorhexidine digluconate and amine fluoride/stannous fluoride-containing mouthrinses, in vitro.

OBJECTIVE: The aim if this study was to determine the minimal inhibitory concentrations of chlorhexidine digluconate and an amine fluoride/stannous fluoride-containing mouthrinse against Porphyromonas gingivalis and mutans streptococci during an experimental long-term subinhibitory exposition. MATERIAL AND METHODS: Five P. gingivalis strains and four mutans streptococci were subcultivated for 20-30 passages in subinhibitory concentrations of chlorhexidine digluconate or an amine fluoride/stannous fluoride-containing mouthrinse. RESULTS: Pre-passaging minimal inhibitory concentrations for chlorhexidine ranged from 0.5 to 2 mg/l for mutans streptococci and from 2 to 4 mg/l for the P. gingivalis isolates. For the amine fluoride/stannous fluoride-containing mouthrinse minimal inhibitory values from 0.125 to 0.25% for the mutans streptococci and from 0.063 to 0.125% for the P. gingivalis isolates were determined. Two- to fourfold increased minimal inhibitory concentrations against chlorhexidine were detected for two of the five P. gingivalis isolates, whereas no increase in minimal inhibitory concentrations was found for the mutans streptococci after repeated passaging through subinhibitory concentrations. Repeated exposure to subinhibitory concentrations of the amine fluoride/stannous fluoride-containing mouthrinse did not alter the minimally inhibitory concentrations of the bacterial isolates tested. CONCLUSION: Chlorhexidine and the amine fluoride/stannous fluoride-containing mouthrinse are effective inhibitory agents against the oral bacterial isolates tested. No general development of resistance against chlorhexidine or the amine fluoride/stannous fluoride-containing mouthrinse was detected. However, some strains showed potential to develop resistance against chlorhexidine after prolonged exposure. CLINICAL RELEVANCE: The use of chlorhexidine should be limited to short periods of time. The amine fluoride/stannous fluoride-containing mouthrinse appears to have the potential to be used on a long-term basis.

Volatile compounds of Salvadora persica inhibit the growth of oral Candida species.

OBJECTIVE: The antibacterial effect of Salvadora persica has been demonstrated both in vitro and in vivo. However, data on its possible antifungal effect is scarce. Therefore, the aim of the present study was to investigate the antifungal effect of solid or pulverized S. persica on clinically important oral Candida species in vitro. DESIGN: The antifungal activity of S. persica was examined against reference strains and clinical isolates of oral Candida species by two different methods. In an agar diffusion test, solid as well as pulverized pieces of S. persica were tested. Mounting the S. persica test specimens inside the lid tested growth inhibition by volatile compounds. RESULTS: S. persica exhibited antifungal activity against all Candida species tested. In particular, the volatile compounds of solid test specimens demonstrated strong growth inhibition, whereas pulverized S. persica revealed no antifungal activity. Parameters such as storage and incubation time as well as the diameter of the sticks influenced the growth inhibition. CONCLUSIONS: Volatile compounds of S. persica have antifungal activity against oral Candida species. Storage time after harvesting may play an important role for the strength of this antifungal activity.

The antimicrobial activity of alpha-bisabolol and tea tree oil against Solobacterium moorei, a Gram-positive bacterium associated with halitosis.

OBJECTIVE: To investigate the antimicrobial effect of alpha-bisabolol and tea tree oil alone and in combination against the halitosis-associated Gram-positive bacillus Solobacterium moorei. DESIGN: The inhibitory activity of alpha-bisabolol and tea tree oil against the reference strain S. moorei CCUG39336 and four clinical S. moorei isolates was investigated by a direct exposure test. Additionally, the ability of alpha-bisabolol to increase the sensitivity of S. moorei was tested by pretreating the bacteria with sublethal concentrations prior to the administration of tea tree oil. RESULTS: A dose-dependent killing was observed for the antimicrobial agents in a direct exposure test with the reference strain S. moorei CCUG39336. Concentrations of ≥0.5% tea tree oil caused decreases in viability of >5 log colony forming units/ml even after short incubation periods, while bacterial viability was less affected by alpha-bisabolol. The combination of 0.1% alpha-bisabolol plus 0.05% tea tree oil showed a synergistic effect on S. moorei strain CCUG39336 and on two of the four clinical S. moorei isolates tested. However, incubation of S. moorei with a sublethal concentration of 0.1% alpha-bisabolol for three days prior to the administration of 0.05% tea tree oil did not enhance the antibacterial effect of tea tree oil. CONCLUSION: Halitosis-associated bacterium S. moorei is susceptible to the antimicrobial agents tea tree oil and alpha-bisabolol, suggesting that these compounds might be beneficial in oral healthcare products.

Additive or synergistic antimicrobial effects of amoxicillin and metronidazole on whole plaque samples: a preliminary report.

OBJECTIVE: In vitro data on the susceptibility of oral bacteria to the combination of metronidazole and amoxicillin is limited. The aim of this preliminary study was to determine the susceptibility of whole subgingival plaque samples to amoxicillin and metronidazole and to their combination. METHODS: Prior to any treatment procedures subgingival plaque samples from patients with severe generalized periodontitis were taken. Appropriate dilutions were plated on Columbia blood agar supplemented with the following agents: 3 µg/mL amoxicillin, 8 µg/mL amoxicillin, 8 µg/mL metronidazole, 16 µg/mL metronidazole, 3 µg/mL amoxicillin plus 8 µg/mL metronidazole or 8 µg/mL amoxicillin plus 16 µg/mL metronidazole. All plates were incubated anaerobically at 36°C for 14 days and the colony forming units (CFU) were determined. RESULTS: Both applied metronidazole concentrations were able to decrease the CFU counts by approximately one order of magnitude in a log10 scale. Amoxicillin 3 µg/mL revealed a reduction of 2.4 log 10 CFU, whereas 50% of the samples did not grow on the plates supplemented with 8 µg/mL of amoxicillin. There was no anaerobic bacterial growth on agar plates supplemented with the combination of amoxicillin and metronidazole even at the lower antibiotic concentrations. CONCLUSION: Susceptibility screening of subgingival samples to metronidazole and amoxicillin and to their combination seems to offer a rational basis for the selection of adjunctive antibiotic therapy.

Antimicrobial efficacy of 3 oral antiseptics containing octenidine, polyhexamethylene biguanide, or Citroxx: can chlorhexidine be replaced?

BACKGROUND: Use of oral antiseptics decreases the bacterial load in the oral cavity. OBJECTIVE: To compare the antimicrobial activity of 3 novel oral antiseptics with that of chlorhexidine, which is considered the "gold standard" of oral hygiene. DESIGN: Comparative in vitro study. METHODS: Four common oral microorganisms (Streptococcus sanguinis, Streptococcus mutans, Candida albicans, and Fusobacterium nucleatum) were tested under standard conditions and at different concentrations, by use of a broth dilution assay and an agar diffusion assay and by calculating the log10 reduction factor (RF). The antimicrobial activity of each antiseptic was assessed by counting the difference in bacterial densities (ie, the log10 number of colony-forming units of bacteria) before and after the disinfection process. RESULTS: The oral antiseptics containing octenidine (with an RF in the range of 7.1-8.24 CFU/mL) and polyhexamethylene biguanide (with an RF in the range of 7.1-8.24 CFU/mL) demonstrated antimicrobial activity comparable to that of chlorhexidine (with an RF in the range of 1.03-8.24 CFU/mL), whereas the mouth rinse containing Citroxx (Citroxx Biosciences; with an RF in the range of 0.22-1.36 CFU/mL) showed significantly weaker antimicrobial efficacy. Overall, octenidine and polyhexamethylene biguanide were more active at lower concentrations.conclusion. Oral antiseptics containing the antimicrobial agent octenidine or polyhexamethylene biguanide may be considered as potent alternatives to chlorhexidine-based preparations.

Antimicrobial susceptibility of periodontopathogenic bacteria.

OBJECTIVES: The aim of this study was to evaluate the resistance profiles of Aggregatibacter (Actinobacillus) actinomycetemcomitans, Porphyromonas gingivalis and Prevotella intermedia/Prevotella nigrescens and to detect possible changes in antibiotic resistance over the time period of 1991-2005. METHODS: A. actinomycetemcomitans (125 strains), P. gingivalis (152 strains) and P. intermedia/P. nigrescens (326 strains) isolated during the years 1991-2005 were tested for their susceptibility to amoxicillin/clavulanic acid, clindamycin, metronidazole, phenoxymethylpenicillin and tetracycline using the Etest. RESULTS: No antibiotic resistance was detected in P. gingivalis, whereas a few isolates of P. intermedia were not susceptible to clindamycin (0.9%), phenoxymethylpenicillin (13.5%) or tetracycline (12.6%). Amoxicillin/clavulanic acid, tetracycline and metronidazole were the most effective antibiotics against A. actinomycetemcomitans with 0%, 0.8% and 20.8% non-susceptible isolates, respectively. However, 88% of the A. actinomycetemcomitans isolates were non-susceptible to phenoxymethylpenicillin and 88% to clindamycin. When strains isolated in the years 1991-94 were compared with those isolated in the years 2001-04, there was no statistically significant difference in the percentage of A. actinomycetemcomitans strains non-susceptible to clindamycin, metronidazole or phenoxymethylpenicillin, or in the percentage of P. intermedia strains non-susceptible to phenoxymethylpenicillin or tetracycline (P > 0.4 each). CONCLUSIONS: Increasing antibiotic resistances in periodontopathogenic bacteria are not yet a problem in the Northern part of Switzerland.

Adhesion of Streptococcus sanguinis to dental implant and restorative materials in vitro.

Bacterial adhesion to tooth surfaces or dental materials starts immediately upon exposure to the oral environment. The aim of this study, therefore, was to compare the adhesion of Streptococcus sanguinis to saliva-coated human enamel and dental materials - during a one-hour period - using an in vitro flow chamber system which mimicked the oral cavity. After fluorescent staining, the number of adhered cells and their vitality were recorded. The dental materials used were: titanium (Rematitan M), gold (Neocast 3), ceramic (Vita Omega 900), and composite (Tetric Ceram). The number of adherent bacterial cells was higher on titanium, gold, and ceramic surfaces and lower on composite as compared to enamel. As for the percentage of adherent vital cells, it was higher on enamel than on the restorative materials tested. These results suggested that variations in the number and vitality of the adherent pioneer oral bacteria, S. sanguinis, in the in vitro system depended on the surface characteristics of the substratum and the acquired salivary pellicle. The in vitro adhesion model used herein provided a simple and reproducible approach to investigate the impact of surface-modified dental materials on bacterial adhesion and vitality.

Clinical effectiveness of two different toothbrushes in the elderly.

Proper tooth brushing is the simplest way to maintain oral health. Still, it can cause considerable manipulative difficulties among parts of the population, like the elderly. The aim of this study was to evaluate a tool that could make tooth-brushing more effective and easier for this age group. Therefore, in a population of 34 elderly people aged 65 and over, we compared the plaque-removing ability of the Superbrush, a three-headed toothbrush, with the Elmex interX and the toothbrush normally used. A balanced cross-over design was chosen and the study was operator-blind. Two indices were used to measure the plaque-removing abilities of the toothbrushes, the OHI (Quigley-Hein plaque index) and the API (proximal plaque index). Professional tooth cleaning was performed to obtain a plaque-free condition at the beginning of the study as well as before switching to a new toothbrush. After one week of using each toothbrush, the OHI and API were determined to assess the oral hygiene status of each participant. The overall plaque removal was similar for the Superbrush, the Elmex interX and the patients' own toothbrushes. However, at the oral surfaces of the teeth, the Superbrush was significantly more effective than the other toothbrushes. No or only small differences were found for other surfaces (posterior and front teeth and facial surfaces).

Complete genomic nucleotide sequence of the temperate bacteriophage Aa Phi 23 of Actinobacillus actinomycetemcomitans.

The entire double-stranded DNA genome of the Actinobacillus actinomycetemcomitans bacteriophage Aa Phi 23 was sequenced. Linear DNA contained in the phage particles is circularly permuted and terminally redundant. Therefore, the physical map of the phage genome is circular. Its size is 43,033 bp with an overall molar G+C content of 42.5 mol%. Sixty-six potential open reading frames (ORFs) were identified, including an ORF resulting from a translational frameshift. A putative function could be assigned to 23 of them. Twenty-three other ORFs share homologies only with hypothetical proteins present in several bacteria or bacteriophages, and 20 ORFs seem to be specific for phage Aa Phi 23. The organization of the phage genome and several genetic functions share extensive similarities to that of the lambdoid phages. However, Aa Phi 23 encodes a DNA adenine methylase, and the DNA packaging strategy is more closely related to the P22 system. The attachment sites of Aa Phi 23 (attP) and several A. actinomycetemcomitans hosts (attB) are 49 bp long.