Early microbial colonization of permucosal implants in edentulous patients.

In edentulous patients, the microbial colonization of permucosal implants of sintered hydroxyapatite was studied. Samples were taken from mucosa and dentures before insertion of implants and from supra- and subgingival sites two to 10 weeks after insertion. In total, five patients and 10 implants with clinically healthy peri-implant tissues were studied. The samples were investigated by dark-field microscopy and anaerobic culture. The supragingival plaque of the implants was dominated by Gram-positive cocci and rods, the subgingival plaque by Haemophilus spp. and Veillonella parvula. A group of bacteria was found specifically related to the implants: Actinomyces odontolyticus, Peptostreptococcus micros, Haemophilus actinomycetemcomitans, Eikenella corrodens, Capnocytophaga sputigena, and Leptotrichia buccalis. Black-pigmented Bacteroides was not found in any of the examined samples. Spirochetes were observed in denture plaque samples and in supragingival plaque of the implants. It is concluded that bacteria known as potential periodontal pathogens colonize the permucosal implants in the first weeks after insertion. The presence of these species seems to be dependent on the ecological factors provided by the artificial gingival crevice of the permucosal implants in the edentulous mouth.

Metronidazole concentrations in human plasma, saliva, and gingival crevice fluid after a single dose.

Metronidazole concentrations were estimated in four human volunteers after a single dose of 750 mg taken orally. Samples of blood, saliva, and gingival crevice fluid were collected before intake and during the following 24 hours. The concentrations of metronidazole in plasma and saliva were measured by high-performance liquid chromatography (HPLC). The concentrations in gingival fluid were estimated by a capillary agar-diffusion assay. The results of the metronidazole measurements as obtained by both methods were significantly correlated. The peak concentrations of metronidazole in plasma and saliva were in the same range, 8.7-13.8 micrograms/mL, and similar concentrations were found in the gingival fluid samples. It is concluded that metronidazole taken orally has similar pharmacokinetics in both saliva and plasma, and that a single oral dose of 750 mg metronidazole leads to a concentration of the drug in the gingival crevice fluid that exceeds the minimal inhibitory concentration for most anaerobic oral micro-organisms.

Effect of splint placement on black-pigmented Bacteroides and spirochetes in the dental plaque of beagle dogs.

The gingival microbiota in beagle dogs was investigated during a period of 42 days after the placement of continuous wire and arch bar splints. The splints were found to induce an increase in helicoidal-shaped micro-organisms and black-pigmented Bacteroides. Two different asaccharolytic Bacteroides types were isolated and tentatively identified as B. gingivalis and B. asaccharolyticus. In addition, B. intermedius-like organisms were isolated. The last two species were observed only after splint placement. The local accumulation of helicoidal-shaped micro-organisms in the epithelial tissue rather than in the micro-ulcerations was regarded as an indication of an active role for these spirochetes in the disease process. The observed shift toward tissue-invading and potentially pathogenic micro-organisms after splinting stresses the need for antimicrobial measures during splint placement in order to minimize periodontal destruction.

Cariogenicity depends more on diet than the prevailing mutans streptococcal species.

This review aims to compare the occurrence and distribution of mutans streptococci in Africa, Europe, and North America and in addition will try to offer explanations for existing relationships among salivary mutans streptococci counts, dietary patterns, and dental caries. The literature reveals that salivary mutans streptococci counts in child populations of the three continents are comparable. The distribution of mutans streptococci species, with a predominance of S. mutans followed by S. sobrinus, and the virtual absence of other mutans streptococci species are also comparable. Although it is widely believed that diet has an important effect on mutans streptococci counts, this review provides evidence that this does not hold true when variations in dietary patterns are moderate, as they normally are in real-life situations. Since the diets of the child populations in the three continents vary moderately, a strong dietary-induced effect on salivary mutans streptococci counts cannot be expected. The observed analogous salivary mutans streptococci counts in these child populations are thus 'not surprising' but are in accordance with the conceptual expectation. The differences in caries experience in children of the three continents cannot be explained by the prevailing mutans streptococci species but instead should be attributed to differences in the cariogenicity of the various diets. The fact that the cariogenicity of the diet determines the development of dental caries while hardly affecting the mutans streptococci counts explains the limited value of the latter as an indicator of dental caries. The reviewed literature shows that mutans streptococci are ubiquitous in children aged 7 years and older in Africa, Europe, and North America. Mutans streptococci should therefore be considered as belonging to the indigenous microflora of the human mouth.

The effect of amoxicillin on destructive periodontitis. A case report.

In a 22-year-old female patient, advanced localized periodontal destruction was observed. The planned treatment consisted of oral hygiene instructions, professional plaque control, deep scaling and root planning and finally modified Widman flap surgery. One molar had to be extracted but was left untreated initially as a control. During the treatment period of 9 months and during 1 year thereafter, samples were taken of the subgingival plaque for dark-field microscopy. The unplanned use of amoxicillin by the patient for a middle ear infection resulted in a suppression below detection level of spirochetes at the investigated sites. At the nontreated control site, the absence of spirochetes was accompanied by a 3-mm reduction of pocket depth and a 2-mm gain in clinical probing attachment, while some formation of new alveolar bone was observed. At the treated sites, clinical improvement was observed. However, a distinction between the effect of the periodontal therapy and the nonscheduled use of amoxicillin could not be made at the treated sites. It is concluded that a single course of systematically administered amoxicillin changed the composition of the subgingival microflora over a long period of time (17 months) and had a beneficial effect upon the status of the periodontium.

Fermentation of carbohydrates in different flours by Streptococcus mutans.

The ability of Streptococcus mutans to ferment carbohydrates and to produce acid was investigated in different flours in vitro. The amounts of acid produced suggest a possible ecological role of the tested flours in the occurrence of Strep. mutans in dental plaque.

[A.a.: the bacterium with the long name]. / A.a.: de bacterie met de lange naam.

The introduction of Kodak's chairside test kit, Evalusite, for Actinobacillus actinomycetemcomitans (A.a.) and two other oral bacteria has stimulated this study of the relation between A.a. and periodontal destruction. A.a. has been associated with oral abscesses, brain abscesses, endocarditis and localized juvenile periodontitis. However, in all periodontal studies A.a. also has been observed in 'ordinary' periodontal pockets and subjects without active periodontal destruction. Based on longitudinal studies it is concluded, that there is no proof for a causal relationship between A.a. and periodontal destruction, that the detection of A.a. is not indicative for future alveolar bone loss and that the sensitivity of a test of A.a. is too low for the diagnosis of progressive periodontitis. The sheer presence of A.a. in spite of its virulence factors is not sufficient to cause periodontal destruction. It is stated that, in order to prevent overtreatment and medicalization, the use of bacteriological tests and broad spectrum antibiotics should be restricted to patients with progressive periodontal destruction not responding to standard treatment.

[Microbiological tests of patients at risk]. / Cariës. Microbiologische detectie van risicopatiënten.

The Streptococcus- and Lactobacillus-tests available in The Netherlands for the selection of patients at risk are discussed. Attention is paid tot the calculation of sensitivity, specificity and predictive value of microbiological tests. Although the predictive values or diagnostic power of the saliva tests are rather low, the use of such tests in dental practice is advocated.

[Bacteriological tests in periodontal practice]. / Bacteriologische tests in de parodontale praktijk.

The specificity, sensitivity and predictive value of bacteriological tests in periodontology are reviewed. It is stated that the bacteriological aim in periodontal therapy is the change of the subgingival flora in a facultative flora which is compatible with the host. Bacteriological tests can be used to identify indicator bacteria. It is discussed how a microscopical or a bacteriological identification test can support periodontal diagnoses and indication of periodontal therapy.

[Individual risk assessment of caries]. / Bepaling van het individuele cariësrisico.

The estimation of individual caries risk factors and the related preventive treatment in the dental practice are discussed. Salivary counts of mutans streptococci and lactobacilli reflect the bacteriological attack (mutans streptococci) and sugar intake (lactobacilli). Caries resistance can be estimated by measurement of the salivary secretion rate and buffer capacity. Treatment of high caries risk patients should be directed against etiological factors. Salivary flow rates and buffer capacity can be stimulated by daily (sugar-free) gum-chewing. For the use of fluoridated toothpaste and sugar intake the dentist is dependent upon the cooperation of the patient. The bacteriological factor in the caries process can be suppressed by application of chlorhexidine varnish.

[How sensible are bacteriological tests in periodontology?]. / Hoe zinvol zijn bacteriologische testen in de parodontologie?

Periodontitis is a mixed infection with subgingival bacteria that belong to the microflora of the host. The bacteriological tests (Microscopy, Culture, Omnigene, Affirm DP and Evalusite) are mainly aimed at spirochetes or A. actinomycetemcomitans, P. gingivalis and P. intermedia. The detection limits of the different tests vary and, therefore, the detection levels are between 0.01-10% of the subgingival microflora. However, threshold levels to distinguish between diseased and carrier state are not established and the low sensitivity and specificity of the tests limit their diagnostic usefulness. The correlation between the tested bacteria and periodontitis does not mean a causal relationship. As a result, the justification of the elimination of the tested bacteria is questionable. The tests of the subgingival plaque do not only add to the microbiological knowledge, but might also promote the overtreatment with antibiotics, such as the in the Netherlands popular combination of amoxicilline and metronidazole. The balance between host and microflora can be restored in most patients by mechanical elimination of the mainly Gram negative anaerobic subgingival plaque. In special occasions metronidazole can be empirically prescribed in order to support the subgingival debridement. In the relatively rare occasions of superinfection, a sensitivity test of the subgingival microbiota is recommended.

[Antibiotic use in periodontics. Results from a research study]. / Antibioticumgebruik in de parodontale praktijk. Resultaten van een verkennend onderzoek.

The sensitivity of the subgingival plaque for amoxicillin, doxycycline, ofloxacin and clindamycin was estimated by agar diffusion disks and Etest in 22 periodontal patients. The sensitivity of the subgingival plaque varied per patient. Resistance of the subgingival plaque for amoxicillin was observed in 50% of the patients and was significantly related to the use of antibiotics in the previous 6 months. The resistance to clindamycin was 68% and to doxycycline 82%. The resistance of the subgingival plaque to these antibiotics could not be related to the previous use. A decision-tree was constructed including a step wise use of a microscopical spirochete test and an antibiotic sensitivity test of the subgingival microflora for the above mentioned antibiotics. The clinical implications of the observed long lasting antibiotic resistance and the practical use of a decision-tree including a spirochete test and antibiotic sensitivity tests need further investigation.

[Prescription of antibiotics for the prevention of bacterial endocarditis by dentists in the Netherlands]. / Het voorschrijven van antibiotica ter preventie van bacteriële endocarditis door tandartsen in Nederland.

In 1993 a representative sample of dental practitioners in the Netherlands was questioned on the use of antibiotics for the prevention of endocarditis in the previous year. Most of the responding dentists (67%) reported prescription of antibiotics for patients at risk. Some of them prescribed an antibiotic regimen that differed from the guidelines drawn up by the Dutch Heart Foundation. In 1992 only 47% of the responding dentists prescribed antibiotics for the prevention of endocarditis entirely according to these guidelines.

[Prescription of antibiotics for periodontitis patients by dental practitioners in the Netherlands]. / Het voorschrijven van antibiotica bij parodontitis-patiënten door tandartsen in Nederland.

In 1993 a representative sample of dentists in the Netherlands was questioned on the use of antibiotics in the treatment of periodontitis. It was found dat 50% of the general practitioners had a positive attitude, 15% a negative one and 35% had an indifferent attitude towards the use of antibiotics in periodontal treatment. Almost 40% of them indicated the prescription of antibiotics for periodontal reasons in the previous year. Most of the dentists (71%) prescribed a combination of metronidazole and amoxicillin. The average prescription frequency in 1992 was 18 times. The prescription frequency and the choice of a combination of metronidazole and a broad spectrum penicillin in the treatment of periodontitis is discussed, emphasizing the importance of the traditional mechanical therapy, the disturbance of the colonization resistance by means of antibiotics and the worldwide concern about the usage of antibiotics.

[Routine dental examination as evaluation tool in clinical cariology]. / Het periodiek tandheelkundig controleonderzoek als evaluatie-instrument in de klinische cariologie.

As a result of the caries prevalence of the Dutch population the character of the routine dental examination is changing. Caries screening remains relevant for high caries risk individuals but the interpretation of early caries lesions deserves more attention, especially the assessment of progression of caries lesions in time. Diagnosis of caries by dental practitioners in the Netherlands mainly consists of visual inspection in combination with bitewing radiography and both methods play an important role in the timing of bitewing radiographs and forthcoming recall visits for oral health examination. The content and frequency of the routine dental examination are discussed in relation to the individual risk prediction as relevant aspects of quality of dental care in the Netherlands.