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Nú eru næstum tvö ár liðin frá því að nýja kórónuveiran SARS-CoV-2 hóf að breiðast út um allan heim frá Wuhan í Kína og leiddi til heimsfaraldurs kórónuveirunnar (COVID-19). Einkenni COVID-19 geta verið allt frá vægum einkennum í öndunar- og meltingarfærum til alvarlegrar lungnabólgu og jafnvel dauða. Ný stökkbreytt afbrigði sem hafa hugsanlega í för með sér breytingar á klínískum eiginleikum, svo sem smithættu, alvarleika sjúkdóms og virkni bóluefnis, hafa reglulega komið fram. SARS-CoV-2 smitast fyrst og fremst með seyti frá öndunarvegum. Veiran finnst oft í munnvatni smitaðra sjúklinga, hvort sem þeir eru einkennalausir eða ekki. Það hefur valdið verulegum áhyggjum vegna hættu á smiti milli tannlækna og sjúklinga við tannlæknaþjónustu. Því var aðgangur að tannlæknaþjónustu sem ekki var brýn mjög takmarkaður í upphafi heimsfaraldursins. Af því leiðir að uppsöfnuð þörf er á tannlæknaþjónustu og hætta á að tafir verði á meðferð. SARS-CoV-2 veiran getur borist í þekjufrumur í munnholi og munnvatnskirtla. Enn sem komið er eru engar vísbendingar um að SARS-CoV-2 sýking í munnholi hafi verið staðfest með veirugreiningu. Vísbendingar eru um að slök munn- og tannheilsa, einkum tannhaldsbólga, geti gert COVID-19 sýkingu verri. Það getur gerst með þeim hætti að bakteríur í munnholi berist í öndunarveg og valdi þannig samsýkingu, eða vegna altæks bólguástands af völdum tannhaldsbólgu. Þörf er á frekari rannsóknum til að meta hugsanleg áhrif SARS-CoV-2 veirunnar á munnheilsu og almennt heilbrigði. Lykilorð: SARS-CoV-2, COVID-19, munnvatn, munnslímhúð, munnvatnskirtlar, smitvarnir

Teeth are colonized by oral bacteria from saliva containing more than 700 different bacterial species. If removed regularly, the dental biofilm mainly comprises oral streptococci and is regarded as resident microflora. But if left undisturbed, a complex biofilm containing up to 100 bacterial species at a site will build up and may eventually cause development of disease. Depending on local ecological factors, the composition of the dental biofilm may vary considerably. With access to excess carbohydrates, the dental biofilm will be dominated by mainly gram-positive carbohydrate-fermenting bacteria causing demineralization of teeth, dental caries, which may further lead to inflammation and necrosis in the pulp and periapical region, i.e., pulpitis and periapical periodontitis. In supra- and subgingival biofilms, predominantly gram-negative, anaerobic proteolytic bacteria will colonize and cause gingival inflammation and breakdown of supporting periodontal fibers and bone and ultimately tooth loss, i.e., gingivitis, chronic or aggressive periodontitis, and around dental implants, peri-implantitis. Furthermore, bacteria from the dental biofilm may spread to other parts of the body by bacteremia and cause systemic disease. Basically, prevention and treatment of dental biofilm infections are achieved by regular personal and professional removal of the dental biofilm.

In 2005, a new curriculum was introduced at the School of Dentistry at the University of Copenhagen. Amongst many changes, the pedagogical concept behind theoretical teaching was changed. The main emphasis was previously on lectures and teacher controlled teaching, but the emphasis has now shifted to a more dialogue-based teaching style for smaller groups where the students became much more active. Thus, the learning principle was now given the pride of place. The present article focuses on the pedagogical reorganisation of the course in oral microbiology where, based on interviews with students and teachers, an evaluation is made regarding how the changes were implemented and developed. Despite the fact that the students themselves wanted to abandon the lecture-based teaching style, there was great dissatisfaction with the new dialogue-based teaching style as the students did not think that it was possible for them to take responsibility for their learning. They would much rather listen to teachers who know the material. Initially, the teachers were very surprised by the negative attitude of the students and had to change the teaching style to more traditional teaching in groups whilst still maintaining the dialogue principle to a certain degree. In this article, the need to enter into a teaching contract between students and teachers prior to introducing new pedagogical principles is discussed.

The purpose of the present study was to encourage reflective dental students by performing an educational Objective Structured Clinical Examination (OSCE) with an element of self- and peer-assessment. An interdisciplinary OSCE comprising cariology, endodontics and microbiology was set up for all third-year students. A blueprint secured representation of the skills to be tested, i.e. knowledge, interdisciplinary knowledge, communication, clinical reasoning and practical procedures. At each station positive and constructive feedback was given to the students based on predefined criteria. Further, the students received written marks after completion of the OSCE. At one station the feedback and marks were replaced by self- and peer-assessment performed by the students in groups after the OSCE. Afterwards, the 68 students and 8 teachers participating in the OSCE answered a questionnaire on their opinion and perception of the examination. The results showed good correlation between the marks given and the students' perception of task difficulty. Generally, there were no systematic variations in the marks given during the week or by individual assessors at the same station, except for one, as well as agreement with marks of the ordinary clinical assessment. The marks given during self- and peer-assessment differed widely, indicating a need for training in this aspect. The questionnaires revealed a very positive perception of the OSCE from both students and teachers. Thus, the majority found the examination relevant and of educational benefit, capable of improving the learning of the students and useful for assessment purposes. Also, the self- and peer-assessment was found useful by the students. In conclusion, this interdisciplinary OSCE stressing constructive feedback to the students was perceived very positively by students and teachers and recognised for its beneficial possibilities in education and assessment.

UNLABELLED SCIENTIFIC RATIONALE FOR STUDY: Bacteremia occurs with various frequency after oral procedures. Periodontal disease may affect the incidence, magnitude, duration and bacterial spectrum of bacteremia. PRINCIPLE FINDINGS The incidence and magnitude of bacteremia after scaling was significantly higher in periodontitis than in gingivitis patients and healthy control individuals. In periodontitis patients, the magnitude of bacteremia was associated with gingival index, plaque index and number of sites with bleeding on probing, but not with probing pocket depth measurements. PRACTICAL IMPLICATIONS The prevention and treatment of periodontal diseases appear to be crucial for the prevention of bacteremia associated with oral procedures.

The susceptibility of Porphyromonas gingivalis to amoxicillin, doxycycline and metronidazole was determined by a standardized method taking into account the biofilm mode of growth of subgingival bacteria. The minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of 48-h biofilms of P. gingivalis established on membrane filters in a Modified Robbins Device were determined by agar dilution. The results were compared to (i) conventional MIC determinations, (ii) the susceptibility of planktonic cultures with cell numbers equal to those of the biofilms, and (iii) results for detached biofilm cells. The MICs of the biofilms of the six reference strains and clinical isolates containing 10 7-8 cells/filter were much higher than the conventional MIC values. However, the MIC of planktonic cultures of equal cell numbers also increased, indicating that an inoculum effect is part of the explanation of the increased resistance of biofilms. Still, the MBCs of biofilms were 2-8 times, and those for doxycycline up to 64 times, greater than the MBC values for planktonic cultures.

The contamination level of alginate impressions delivered to a large dental laboratory in Sweden was determined. One hundred and seven consecutive alginate impressions were included during 7 days. Samples were taken and transferred into sterile physiological saline and analysed microbiologically for colony-forming units (cfu) as well as nonhemolytic, alpha-hemolytic, and beta-hemolytic colonies. After sampling, the clinics were contacted and asked to fill in simple questionnaires about their routines of disinfecting impressions. The questionnaire study revealed that about half of the clinics had some kind of disinfection routine, while the others rinsed in running water only. Seventy-two percent of the impressions yielded growth of bacteria, with a median number of 1.3x10(2) cfu. Thirteen per cent of the samples yielded10(3) cfu, with a maximum number of 3.4x10(4) cfu. The majority of isolates were non- and alpha-hemolytic bacteria. Growth was recorded in 61.3% of disinfected impressions, and the numbers of bacteria in disinfected and nondisinfected impressions were similar. These findings raise the question of whether impressions need to be disinfected or if proper handling and hygienic procedures are sufficient to block the possible route of infection.

This study examined the cultivable microflora before and after stepwise excavation procedures in deep carious lesions in 9 permanent teeth, categorized according to degrees of proximal surface destruction. The final excavation was performed 4–6 months after the initial treatment, which included peripheral dentine excavation and removal of the central cariogenic biomass and the superficial necrotic dentine. Dentine colour and consistency were assessed by means of standardized scales before the application of a Ca(OH)2 compound and temporary sealing. Reassessments were performed before and after the final excavation. Microbiological samples of the central demineralized dentine were obtained with a sterile bur before and after the first excavation, as well as before and after the final excavation. After anaerobic cultivation on enriched non–selective tryptic soy agar, 30 colonies from a representative area were identified by standardized biochemical and physiological tests. Before temporary restoration, a yellowish and light brown demineralized soft dentine was typically observed, and gram–positive rods accounted for 70% and lactobacilli for 50% of the total colony–forming units. Lactobacillus casei subsp. rhamnosus and Actinomyces naeslundii dominated the lactobacilli and the other gram–positive rods, respectively. Gram–negative rods were the next most frequent isolates, followed by streptococci, each group accounting for about 20% of the colony–forming units in positive samples. Before the final excavation, which did not cause exposure of the pulp in any of the cases, the retained demineralized dentine had changed into a darker and harder tissue, and the total colony–forming units, as well as the frequency and proportions of lactobacilli were substantially reduced. Gram–negative rods also declined, and the flora was dominated by A. naeslundii and various streptococci. In conclusion, the cultivable flora detected following the treatment interval had declined substantially, and the distribution of bacterial species did not represent a typical cariogenic microbiota of deep lesions, confirming the clinical findings of arrested caries progression.

Concern about the survival of microorganisms in deep carious lesions may often lead to unnecessary exposure of the pulp during final excavation. There are reasons, therefore, to initiate systematic studies on the alternative procedure known as stepwise excavation. Clinical evaluation of stepwise excavation was performed on 31 deep carious lesions considered to result in pulp perforation by traditional excavation. This study examines the clinical and microbiological alterations during the final excavation performed during long intervals (6-12 months) after the initial treatment that included peripheral dentine excavation and removal of the central cariogenic biomass and the superficial necrotic dentine. The dentine colour and consistency were assessed by means of standardized scales before application of a Ca(OH)2 compound and a temporary sealing for 6-12 months. Reassessments were performed before the after final excavation. Microbiological dentine samples were obtained in 19 randomly selected lesions by a sterile bur, transferred to and diluted in reduced transport fluid, and plated on tryptic soy agar. After anaerobic incubation at 37 degrees C for 7 days, total colony-forming units per millilitre were counted from (1) peripheral excavated and hard dentine (control), (2) central demineralized dentine before and final excavation, and (3) central dentine after the final excavation. Six samples of central demineralized dentine were without any cultivable flora increasing to 9 samples after the final excavation. The clinical dentine changes occurring during stepwise excavation were characterized by enhanced hardness of the dentine which was associated with a marked reduction in bacterial growth after the final excavation. Despite the presence of bacteria in the excavated dentine none of the carious lesions resulted in pulp perforation, suggesting that the initial removal of the cariogenic biomass appears to be essential for control of caries progression. Stepwise excavation is not only an appropriate treatment of deep carious lesions but is also considered a suitable model for microbiological studies to determine the bacteria persisting in clinically excavated lesions.

Bacteria living in biofilms as dental plaque on tooth surfaces are generally more resistant to antimicrobial agents than bacteria in batch culture normally used for in vitro susceptibility testing. In order to compare the resistance of free-living and surface-grown oral bacteria, the MIC of Streptococcus sanguis 804 and ATCC 10556 to amoxicillin, doxycycline and chlorhexidine was determined by a broth dilution method. Subsequently, S. sanguis biofilms established in an in vitro flow model were perfused with the antimicrobial agents for 48 h at concentrations equal to and up to 500 times the MIC, and biofilm cell number was determined during this period. The antibiotics at the MIC did not affect the cell number of S. sanguis biofilms compared to the starting point, and only after 48 h at 500 times the MIC were the biofilm bacteria eliminated. At intermediate concentrations biofilm cell number gradually decreased. Chlorhexidine also gradually reduced biofilm cell number, but was inhibitory at concentrations closer to the MIC than was the case for the antibiotics. Thus S. sanguis in biofilms survived up to 500 times the MIC found in batch culture for up to 48 h.

Longo Vital® herbal tablets have been shown to have a protective effect against periodontal bone loss in rats. This may be ascribed either to a previously demonstrated immuno-stimulatory effect of the tablets, to an antimicrobial effect of the herbs or to a combination of both. In the present study the in vitro susceptibility of 12 dental plaque bacteria to six individual herbs included in Longo Vital® was determined by a broth dilution method. Paprika, rosemary leaves and peppermint inhibited two thirds of the tested bacteria at 2.8-45 mg/ml, 0.75-12 mg/ml and 3-24 mg/ml corresponding to 0.8-12.5 per cent, 1.6-25 per cent and 12.5-100 per cent of the recommended daily dose, respectively. A combination of paprika and rosemary leaves tested towards five susceptible bacteria revealed a decreased inhibitory effect on two of these bacteria, especially of Actinobacillus actinomycetemcomitans to paprika, but conversely a pronounced increase in susceptibility of Peptostreptococcus anaerobius, Porphyromonas gingivalis and Prevotella intermedia now susceptible to 0.01-0.70 mg/ml of each herb, corresponding to 0.02-0.2 per cent of the recommended daily dose. The active ingredients of the herbs, however, and the concentrations of these obtained in blood and periodontal tissues after ingestion of Longo Vital® are not known.

In 2005, a new curriculum was introduced at the School of Dentistry at the University of Copenhagen. Amongst many changes, the pedagogical concept behind theoretical teaching was changed. The main emphasis was previously on lectures and teacher controlled teaching, but the emphasis has now shifted to a more dialogue-based teaching style for smaller groups where the students became much more active. Thus, the learning principle was now given the pride of place. The present article focuses on the pedagogical reorganisation of the course in oral microbiology where, based on interviews with students and teachers, an evaluation is made regarding how the changes were implemented and developed. Despite the fact that the students themselves wanted to abandon the lecture-based teaching style, there was great dissatisfaction with the new dialogue-based teaching style as the students did not think that it was possible for them to take responsibility for their learning. They would much rather listen to teachers who know the material. Initially, the teachers were very surprised by the negative attitude of the students and had to change the teaching style to more traditional teaching in groups whilst still maintaining the dialogue principle to a certain degree. In this article, the need to enter into a teaching contract between students and teachers prior to introducing new pedagogical principles is discussed.

Treatment of marginal periodontitis may include use of local antibiotics. In the present in vitro study the bioabsorbable materials Surgicel, Tissell, and CollaCote and acrylic strips were examined for release of doxycycline into liquids and residual antibacterial activity of the materials. Pieces of material were incubated in 1 ml of water or human serum which was exchanged every day for 9 days. The concentration of doxycycline in the liquids was measured spectrophotometrically while the residual antibacterial activity of the materials was determined microbiologically. Surgicel constantly showed very high concentrations and level of residual activity. The acrylic strip and CollaCote decreased to low levels of both concentration and residual activity in a few days. Tissell was intermediate with a continuous decrease in concentration but rather high level of residual activity throughout the study. In serum the acrylic strip was partly dissolved and Surgicel was totally dissolved after 2 days. Left undisturbed in serum Surgicel was not dissolved for 2 weeks. These results indicate that Surgicel and Tissel may be capable of prolonged release of doxycycline in vivo.

Bacteremia frequently occurs after dental treatment. Periodontal inflammation may influence the incidence, magnitude and duration of bacteremia. The presence of circulating oral bacteria or bacterial components may induce cytokine synthesis in blood cells, which may contribute to the development or exacerbation of atherosclerosis. The present study tested the hypothesis that bacteremia occurring after scaling in periodontitis patients results in altered plasma levels of cytokines. Twenty periodontitis patients were subjected to scaling. Blood samples at baseline and at 0.5, 10 and 30 minutes postscaling were examined for bacteremia whereas baseline and eight-hour postscaling blood samples were examined for the levels of IL-1beta, TNF-alpha, IL-6, IL-8, IL-10 and IL-12p70. IL-6 levels were significantly increased eight hours after scaling, while IL-8 was significantly decreased. No systematic changes occurred in the levels of IL-1beta, TNF-alpha, IL-10 and IL-2p70. IL-6 levels may be increased while IL-8 may be decreased due to scaling, which may have implications for general health.

Epidemiological studies have shown that periodontitis may be associated with presence of atherosclerosis. DNA from periodontal pathogens has been detected in atherosclerotic lesions, but viable oral bacteria have not yet been isolated from atherosclerotic plaques. The purpose of the present study was to determine if viable oral bacteria could be isolated from atherosclerotic lesions and if DNA from periodontal pathogens could be detected by use of polymerase chain reaction (PCR) techniques.Seventy-nine specimens of atherosclerotic plaque removed from carotid or femoral arteries during surgery were immediately transferred to reduced transport fluid and brought to the laboratory. The calcified tissue was meticulously cut into fine pieces and used for cultivation of Porphyromonas gingivalis, Prevotella intermedia, P. nigrescens, Campylobacter rectus, Actinobacillus actinomycetemcomitans, Tannerella forsythensis, and oral streptococci. The material from 24 of the specimens was homogenized, DNA was extracted, and PCR amplification of 16S rDNA with universal and specific primers was carried out. Finally, the PCR products were sequenced.None of the samples yielded growth of the oral bacteria under investigation. In all the 24 specimens bacterial DNA was detected and likewise DNA of P. intermedia was found in the samples. P. nigrescens and P. gingivalis were found sporadically.Viable oral bacteria could not be isolated from the atheromas, but the data confirm that DNA of periodontal pathogens can be detected in atherosclerotic plaques. However, the finding that DNA from P. intermedia constantly occured in the examined samples was new. Further studies may focus on the simultaneous occurrence of identical clones of this species in subgingival plaque and atherosclerotic plaques.

To evaluate the effect of a disinfectant agent based on hydrogen peroxide (Sterilex Ultra, Sterilex Corporation, Maryland, USA) on the microbiological water quality in dental unit waterlines (DUWL).Six older dental units were disinfected with Sterilex Ultra and another six units with sodium hypochlorite. The results were compared to six non-disinfected units examined during a period without patient treatment.The number of colony forming units of bacteria (cfu)/ml of water was determined according to European Standards on water quality.The water quality was initially determined during a six week period, and subsequently in more detail for two weeks. Finally, the effect of prolonged administration of Sterilex Ultra was investigated for six weeks.Instillation of Sterilex Ultra according to the recommendations of the manufacturer initially reduced the number of bacteria in DUWL to10(2) cfu/ml. However, following daily, as well as prolonged administration of Sterilex Ultra a gradual recolonisation was observed resulting in bacterial numbers10(4) cfu/ml in a number of units. Major differences between the number of cfu/ml in individual units were observed.Neither daily nor extended administration of Sterilex Ultra was capable of maintaining an acceptable water quality in these older dental units.

AIMS/HYPOTHESIS: We investigated the pharmacological properties of two novel ATP sensitive potassium (K(ATP)) channel openers, 6-Chloro-3-isopropylamino-4 H-thieno[3,2- e]-1,2,4-thiadiazine 1,1-dioxide (NNC 55-0118) and 6-chloro-3-(1-methylcyclopropyl)amino-4 H-thieno[3,2-e]-1,2,4-thiadiazine 1,1-dioxide (NN414), on the cloned cardiac (Kir6.2/SUR2A), smooth muscle (Kir6.2/SUR2B) and pancreatic beta cell (Kir6.2/SUR1) types of K(ATP) channel. METHODS: We studied the effects of these compounds on whole-cell currents through cloned K(ATP) channels expressed in Xenopus oocytes or mammalian cells (HEK293). We also used inside-out macropatches excised from Xenopus oocytes. RESULTS: In HEK 293 cells, NNC 55-0118 and NN414 activated Kir6.2/SUR1 currents with EC(50) values of 0.33 micromol/l and 0.45 micromol/l, respectively, compared with that of 31 micro mol/l for diazoxide. Neither compound activated Kir6.2/SUR2A or Kir6.2/SUR2B channels expressed in oocytes, nor did they activate Kir6.2 expressed in the absence of SUR. Current activation was dependent on the presence of intracellular MgATP, but was not supported by MgADP. CONCLUSION/INTERPRETATION: Both NNC 55-0118 and NN414 selectively stimulate the pancreatic beta-cell type of K(ATP) channel with a higher potency than diazoxide, by interaction with the SUR1 subunit. The high selectivity and efficacy of the compounds could prove useful for treatment of disease states where inhibition of insulin secretion is beneficial.

This study compared a visual ranked scoring system and a radiographic ranked scoring system for occlusal caries detection with the level of infection of dentin. Seventy-five third-molars, designated for extraction, were professionally cleaned. Caries was scored according to a visual ranked scoring system at a selected site in the groove-fossa system. Radiographs of the teeth were available and caries was recorded along a five-point ranked scoring system. Each tooth was extracted and hemi-sectioned through the investigation site under aseptic conditions. A burful of dentin was removed from the EDJ of one of the section faces and these samples were processed to establish the level of dentin infection. The depth of the lesion was assessed on the other section face using a five-point ranked histological scoring system. A strong relationship was observed between the histological lesion depth and visual score (r(s)=0.93) while a moderate relationship was seen between lesion depth and radiographic scores (r(s)=0.77). The dentin from teeth with cavities exposing dentin was heavily infected. The dentin from teeth with microcavities or grey discoloration of the dentin was less infected than the lesions with frank cavitation (score 4) (p0.05, t-test), but more infected than the initial lesions (p0.05, t-test). The latter lesions showed minimal infection. A similar tendency was seen with respect to increasing radiographic scores and the level of infection of the dentin.

The purpose of this study was to determine the risk of microbiological transmission into the dental laboratory via impressions and dental stone models. Metal master models were contaminated with Bacillus subtilis and Streptococcus sanguis. Impressions in alginate, polyvinylsiloxane, and polyether were used, and models were cast in two brands of dental stone. Samples were taken from the impression surfaces before and after casting, and sections from the stone models were taken by a technique developed for this study. After incubation, the numbers of colonies were counted and the numbers of colony-forming units per milliliter were calculated. The reductions were statistically significant but considered to be clinically insignificant. The conclusion is that even after severe contamination, the risks to dental laboratory personnel are minimal. "Normal" hygienic procedures are recommended instead of disinfection.

Objective. It has been demonstrated that contamination of the insides of high-speed dental turbines occurs and that bacteria as well as viruses may remain infectious when expelled from such turbines during subsequent use. Consequently, it has been widely recommended that a high-speed turbine be sterilized after each patient. The purpose of this study was to evaluate the effect of steam autoclaving on a high-speed dental turbine with a contaminated turbine chamber. Study Design. Streptococcus salivarius and endospores of Bacillus stearothermophilus were used as test organisms to determine the effectiveness of 4 different small non-vacuum autoclaves and one vacuum autoclave. Results. The study demonstrated different efficiencies among the small non-vacuum autoclaves, the best showing close to a 6 log reduction of the test organisms inside the turbine chamber. When cleaning and lubrication of the high-speed dental turbine was carried out before autoclaving, this level of reduction was observed for all the examined non-vacuum autoclaves. Conclusions. It is concluded that cleaning before sterilization is essential for safe use of high-speed dental turbines and that small non-vacuum autoclaves should be carefully evaluated before being used for the reprocessing of hollow instruments such as high-speed turbines. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1999;87:184-8)

Dental high-speed turbines and handpieces can take up and expel microorganisms during operation and thus need regular sterilization. This study established a method for validating devices used to sterilize high-speed turbines and handpieces. The air and water channels and turbine chambers were contaminated with suspensions of Streptococcus salivarius or endospores of Bacillus stearothermophilus. The effect of flushing and/or autoclaving performed by a new device combining both procedures was evaluated by counting the number of viable bacteria recovered from these devices. Further, the effect on clinically used handpieces was evaluated. In an initial experiment, the device partially reduced S. salivarius, and the endospores survived. In a second experiment, a 5 to 6 log reduction of S. salivarius in air and water channels was obtained. No growth was observed in clinically used high-speed handpieces, and both S. salivarius and endospores were eliminated from the turbine chambers. Thus, the method of validation proved capable of discriminating between different levels of bacterial reduction.

By local delivery of antibiotics to periodontal pockets, very high initial concentrations are often quickly succeeded by subinhibitory concentrations, which may facilitate development of bacterial resistance. The purpose of the present study was to investigate possible development of resistance in suspected periodontal pathogens after exposure to subinhibitory concentrations of metronidazole and minocycline. The minimal inhibitory concentration (MIC) of 18 reference strains and 12 clinical isolates was determined by a broth dilution method. Subsequently, all strains with MIC8 micrograms/ml were exposed to serial passage on plates containing subinhibitory and gradually increasing concentrations of antibiotics, until growth was inhibited. Initially, most strains were inhibited ator = 0.250 microgram/ml of minocycline andor = 0.5 microgram/ml of metronidazole, though A. actinomycetemcomitans was resistant to metronidazole. After growth at subinhibitory concentrations, 8 strains survived 1-2 x and 11 stains survived 8-32 x their initial MIC of metronidazole, growing at up to 8 micrograms/ml. All A. actinomycetemcomitans survived 8-64 x their initial MIC of minocycline, growing ator = 2 micrograms/ml, while all other strains were inhibited ator = 0.250 microgram/ml, corresponding to a 1-8 x increase in their initial MIC. Thus, development of resistance was observed for periodontal bacteria growing at up to 64 x their initial MIC, but the final level of resistance was moderate.

Bacteria in biofilms are known to be more resistant than bacteria in batch cultures to antimicrobial agents. The purpose of the present study was to develop a flow method for formation of oral biofilms permitting susceptibility testing of plaque bacteria. A brain heart infusion (BHI) Streptococcus sanguis 804 culture was pumped through a modified Robbins Device (MRD) with 25 exchangeable silicone disks at 40 ml/h. After 24-48 h disks were removed and biofilm cells dispersed by vortex mixing and low-output ultrasonication. Colony forming units (cfu)/cm2 were determined after aerobic incubation on blood agar plates. Optimal biofilm formation was found after growth for 48 h at 37 degrees C in BHI + 1% sucrose, using saliva-coated silicone disks in inverted MRDs, yielding on average 4.4 x 10(5) cfu/cm2. Similar results were obtained for S. sanguis ATCC 10556 and five clinical isolates. Testing the susceptibility of S. sanguis to chlorhexidine gluconate showed increased resistance of biofilms compared to batch culture. Thus an appropriate biofilm model for susceptibility testing of oral microorganisms has been established.

The purpose of this study was to isolate streptococcal strains from the oral cavities of streptococcal endocarditis patients and compare these strains biochemically and genetically with the corresponding streptococcal blood isolates. Total identity was observed between the blood and oral cavity isolates from the two patients studied.

Topical antimicrobial treatment is appearing as a means of therapy in patients with advanced periodontal disease. The purpose of the present study was to examine the occurrence of doxycycline resistant bacteria in subgingival plaque and oral cavity after local administration of doxycycline. Five patients with advanced marginal periodontitis were scaled, and one approximal pocket in each patient was additionally treated with locally delivered doxycycline. Microbiological samples were obtained from the test site, a contralateral control site and tongue and tonsils before treatment and 3, 13, 26 and 52 weeks after treatment. The occurrence and morphological distribution of doxycycline resistant bacteria was determined after anaerobic cultivation on enriched tryptic soy agar with and without doxycycline incorporated. At the test site and on tongue and tonsils the percentage of doxycycline resistant bacteria increased from less than 1% before treatment to 22% and 35%, respectively, immediately after treatment, but decreased again at week 13. At the control site no increase was observed. Gram-positive cocci constituted the majority of doxycycline resistant bacteria at all 3 sampling sites (73-94%). The morphological distribution of resistant bacteria was not affected by the doxycycline therapy. Thus, local doxycycline therapy resulted only in a transient increase in resistance in the oral microflora.

The purpose of the present study was to introduce an objective structured clinical examination (OSCE) for educational purposes at a dental school with a rather traditional curriculum in order to encourage reflective thinking in the students. Sixty-eight third year students in pairs participated in an interdisciplinary OSCE in cariology and microbiology. All stations were based upon one patient testing knowledge, clinical reasoning, verbal communication and practical procedures. At each station, immediate verbal feedback was given to the students by a teacher on the basis of pre-defined criteria. Further written marks (individual and group averages) were given to the students the following week. After the OSCE, the students and the teachers answered a questionnaire about the OSCE. For practical reasons, the OSCE had to be performed over 3 days and most of the stations to be run by several teachers. The average results obtained by each group did not seem to improve during the week. About half of the students stated not to have discussed the questions with others. There was no apparent systematic variation in the marking of the individual teachers over time. Neither were there major differences between different teachers at the same station, though one teacher marked somewhat lower. Both students and teachers found the OSCE well organised and the questions highly relevant providing an educational benefit. Students as well as teachers perceived the OSCE as a very useful method of clinical assessment, and the vast majority found that OSCEs could also replace parts of the traditional written exams. In conclusion, the OSCE was positively received by students as well as teachers and is recommended for implementation in the curriculum for educational purposes as well as assessment.

Aim: The purpose of the present study was to evaluate the effect of an ultrafiltration system on the bacteriological water quality in dental units. Design: A BIN-X UF-45R ultrafiltration system with a pore membrane of 0.03μm was mounted at the water supply of six older dental units while six control units were disinfected with sodium hypochlorite according to a standard procedure. As the water quality in the test units deteriorated in spite of ultrafiltration the test units were subjected to chlorination at different concentrations several times during the test period. Outcome measure: The number of colony forming units (cfu)/ml in water was determined according to European Standards on water quality. Results: While the median number of cfu/ml in control units never exceeded 7.6×101 the median cfu/ml in test units increased up to > 1×105 in 3–4 days every time chlorination of the units was interrupted. Conclusion: The ultrafiltration system mounted at the water supply for six dental units was not able to control the bacteria originating from the existing biofilm in the water lines and deliver water of an acceptable quality.

The susceptibility of Porphyromonas gingivalis to amoxicillin, doxycycline and metronidazole was determined by a standardized method taking into account the biofilm mode of growth of subgingival bacteria. The minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of 48-h biofilms of P. gingivalis established on membrane filters in a Modified Robbins Device were determined by agar dilution. The results were compared to (i) conventional MIC determinations, (ii) the susceptibility of planktonic cultures with cell numbers equal to those of the biofilms, and (iii) results for detached biofilm cells. The MICs of the biofilms of the six reference strains and clinical isolates containing 107-8 cells/filter were much higher than the conventional MIC values. However, the MIC of planktonic cultures of equal cell numbers also increased, indicating that an inoculum effect is part of the explanation of the increased resistance of biofilms. Still, the MBCs of biofilms were 2-8 times, and those for doxycycline up to 64 times, greater than the MBC values for planktonic cultures.

OBJECTIVE: Infective endocarditis is frequently caused by oral streptococci, especially Streptococcus sanguis. In this group, many strains have recently been reclassified on the basis of new taxonomic schemes. The purpose of this study was to classify oral streptococci from patients with infective endocarditis and, further, to assess the importance of specific virulence factors for the development of streptococcal endocarditis. METHODS: Twenty-eight previously identified and 10 new streptococcal isolates from infective endocarditis were classified according to Kilian et al (1989) and compared to 30 streptococcal isolates from the oral cavities of periodontal patients without endocarditis. Subsequently, surface hydrophobicity was assessed by hydrophobic interaction chromatography, production of extracellular dextran was determined by precipitation, and non-specific proteolytic activity was evaluated by determination of hydrolysis of gelatin, and casein-precipitating activity. RESULTS: Eight streptococcal species were represented in the endocarditis isolates. Most strains were highly hydrophobic and none showed non-specific proteolytic activity. Dextran was produced with similar frequency in endocarditis and non-endocarditis isolates. CONCLUSIONS: The present study showed that infective endocarditis may be caused by a variety of oral streptococcal species. The possible virulence factors investigated were found in the same proportions in endocarditis and non-endocarditis isolates, and thus did not seem to be crucial for development of endocarditis.

Der findes ingen eksakte tal for forekomsten af fødevareallergi i den danske befolkning. Den kumulerede forekomst af fødevareallergi hos børn i de første tre leveår skønnes at være på 7-8 %, hvoraf hovedparten vokser sig fra det. Punktprævalensen af diagnosticeret fødevareallergi hos voksne er 3 %.Det er ofte almindelige fødevarer, som udløser allergiske reaktioner, fx æg, mælk, nødder, skaldyr, jordnødder og frisk frugt. Krydsreaktioner er den mest almindelige fødevareallergi hos større børn og voksne. Pollenallergikere udgør her en særlig risikogruppe, idet op til halvdelen reagerer allergisk på visse typer af frisk frugt og grøntsager, hvilket kan udløse oralt allergisyndrom. Krydsreaktioner kan potentielt også udløses i forbindelse med tandbehandling som følge af eksponering for de forskellige materialer, der anvendes i tandlægepraksis.Det er væsentligt at skelne mellem fødevareallergi og fødevareintolerance. Ved fødevareallergi aktiveres immunsystemet via et IgE-medieret respons. Fødevareintolerance er derimod en form for hypersensibilitet over for et eller flere fødeemner, enten pga. manglende nedbrydning i mave-tarm-kanalen som fx ved laktoseintolerance eller pga. en autoimmunbetinget inflammation i tarmen som ved cøliaki. Den præcise forekomst af fødevareintolerance kendes ikke, men skønnes at være lavere end for fødevareallergi. De mest almindelige former for fødevareintolerance er laktoseintolerance og cøliaki. Udiagnosticeret og ubehandlet kan disse tilstande medføre malabsorption og dermed orale manifestationer som bl.a. emaljedefekter og aftøs stomatitis.Nærværende artikel gennemgår de mekanismer, der ligger til grund for fødevareallergi og -intolerance, de relaterede symptomer og orale manifestationer samt udredning og behandling af disse tilstande.