Salivary levels of suspected periodontal pathogens in relation to periodontal status and treatment

Transmission of periodontal bacteria and models of infection

BACKGROUND

Bacteria play an essential role in the aetiology of periodontitis. Most bacterial species isolated from subgingival plaque are indigenous to the oral cavity. Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis are detected infrequently in periodontal health, which makes these species prime candidates to study person-to-person transmission. The aim of the present study was to review the literature on transmission of these periodontal bacterial species.

METHOD

We review the literature on bacterial typing techniques and summarize the information on clonal distribution of A. actinomycetemcomitans and P. gingivalis in family units based on different typing techniques in order to establish the likelihood for person-to-person transmission of these periodontal pathogens.

RESULTS

Vertical transmission of A. actinomycetemcomitans is estimated to be between 30% and 60%, whereas vertical transmission of P. gingivalis has rarely been observed. Horizontal transmission between spouses ranges between 14% and 60% for A. actinomycetemcomitans and between 30% and 75% for P. gingivalis. There is some evidence to show that cohabitation with a periodontitis patient influences the periodontal status of the spouse; however, substantially more information is needed to prove this hypothesis.

CONCLUSIONS

Transmission of putative periodontal pathogens between family members has been shown. The clinical consequences of these events have been poorly documented. Based on the current knowledge, screening for and prevention of transmission of specific virulent clones of A. actinomycetemcomitans may be feasible and effective in preventing some forms of periodontal disease. P. gingivalis is usually recovered from diseased adult subjects, and transmission of this pathogens seems largely restricted to adult individuals. Horizontal transmission of P. gingivalis may therefore be controlled by periodontal treatment involving elimination or significant suppression of the pathogen in diseased individuals and by a high standard of oral hygiene.

Association between sharing of toothbrushes, eating and drinking habits and the presence of Actinobacillus actinomycetemcomitans in Moroccan adolescents

BACKGROUND/AIMS

Actinobacillus actinomycetemcomitans is frequently detected in dental plaque collected from Moroccan adolescents, and has been shown to be associated with clinical attachment loss in this population. The aim of this study was to assess whether behaviors such as the sharing of toothbrushes, and eating and drinking habits were associated with the presence of A. actinomycetemcomitans in Moroccan adolescents.

MATERIALS AND METHODS

A total of 121 adolescents were clinically examined. Interviews regarding sharing of toothbrushes, eating and drinking habits were performed, and plaque samples were collected and analyzed for A. actinomycetemcomitans with different leukotoxin promoter types by polymerase chain reaction. Based on eating and drinking habits, the study population was divided in a low risk behavior group (LRB) and a high risk behavior group (HRB).

RESULTS

No association was found between the sharing of toothbrushes and the presence of A. actinomycetemcomitans. The odds ratios between the HRB and LRB group for being positive for the JP2 type, for non-JP2 types, and for any type of A. actinomycetemcomitans were 4.74 (95% CI 0.55; 40.71), 2.49 (95% CI 1.03; 5.97), and 2.97 (95% CI 1.28; 6.91), respectively. The difference in the mean number of teeth with a clinical attachment loss of > or = 3 mm between the HRB and the LRB group was 0.91(95% CI 0.09; 1.72).

CONCLUSION

Sharing of toothbrushes does not seem to be associated with the presence of A. actinomycetemcomitans in young Moroccans. Eating and drinking habits conducive to exchange of saliva are positively associated with presence of A. actinomycetemcomitans, and with a higher level of clinical attachment loss.

Facial bite wounds: management update

Bite wounds are frequently located on the face; injuries inflicted by dogs are most common, especially in children. Bacteriology of infected dog and cat bite wounds includes Pasteurella multocida, Staphylococcus aureus, viridans streptococci, Capnocytophaga canimorsus, and oral anaerobes. Infected human bites yield a similar spectrum of bacteria except for Pasteurellae and C. canimorsus; instead human bites are frequently complicated by Eikenella corrodens. Antibiotic therapy against these bacteria is indicated both for infected bite wounds and fresh wounds considered at risk for infection. Amoxicillin-clavulanate (and other combinations of extended-spectrum penicillins with beta-lactamase inhibitors) and moxifloxacin offer the best in vitro coverage of the pathogenic flora. Initial wound management consisting in irrigation and debridement is at least equally important with antibiotics for prevention of infection. The need for prophylaxis against systemic infectious complications, particularly tetanus, should also be evaluated. Primary surgical repair is the treatment of choice for most clinically uninfected facial bite wounds, whereas delayed closure should be reserved for certain high risk or already infected wounds. Avulsive injuries with significant tissue loss represent the most difficult cases for definitive management and are also those most likely to require hospitalization.

Binding of Actinobacillus actinomycetemcomitans lipopolysaccharides to Peptostreptococcus micros stimulates tumor necrosis factor alpha production by macrophage-like cells

Peptostreptococcus micros is a gram-positive bacterium that has been associated with periodontitis and endodontic infections. In this study, we hypothesized that P. micros binds the immunomodulating component lipopolysaccharide derived from gram-negative bacteria to increase its capacity to stimulate cytokine production by host cells. The ability of P. micros to bind Actinobacillus actinomycetemcomitans lipopolysaccharide was demonstrated by an enzyme-linked immunosorbent assay and by immunoelectron microscopy. Pretreatment of P. micros cells with A. actinomycetemcomitans lipopolysaccharide was associated with a 49-fold increase in tumor necrosis factor alpha production by human monocytic cells U937 differentiated into adherent macrophages, compared to the stimulation with untreated P. micros. This effect was suppressed by incorporating polymyxin B, a lipid A-binding substance, during treatment of macrophage-like cells with lipopolysaccharide-coated P. micros cells. This is the first study reporting a binding interaction between lipopolysaccharide and a gram-positive bacterium. This interaction represents a new mechanism that could promote the inflammatory response during periodontitis.

The effect of HAART on salivary microbiota in the Women's Interagency HIV Study (WIHS)

OBJECTIVE

Study the prevalence of potentially pathogenic microorganisms in saliva of HIV-positive women in the Women's Interagency HIV Study.

STUDY DESIGN

157 HIV-positive and 31 HIV-negative women were studied. At baseline and every 6 months over 4 years, information was collected on socioeconomic and educational status, oral and systemic health, including HIV markers and antiretroviral therapy, and frequency of professional oral care utilization. Bacterial and yeast pathogenic isolates from stimulated whole saliva were tentatively identified using standard methodologies.

RESULTS

The prevalence of microorganisms in stimulated saliva of HIV-positive women was not significantly different from that of HIV-negative women. In HIV-positive women, highly active antiretroviral therapy (HAART) was independently and significantly associated with the presence of a variety of salivary bacterial species. HAART increased the risk for recovering Fusobacterium species (P < .001), enteric gram-negative rods (P < .05), Peptostreptococcus micros (P < .05), Campylobacter species (P < .0001), Eubacterium species (P < .001), and Tannerella forsythia (P < .01). In contrast, HAART led to decreased recovery rate of yeasts (Candida albicans and Candida dubliniensis) (P < .0001).

CONCLUSION

The present findings suggest that the institution of HAART promotes an increasingly pathogenic salivary microbiota, at least temporarily. Similar findings have been reported for various nonoral microbial ecosystems.

The effect of periodontal treatment on the salivary bacterial load and early plaque formation

AIM

The purpose of the present study was to investigate in periodontitis patients the relationship between the number of bacteria in the saliva and the amount of de novo plaque formation before and after treatment.

METHODS

At baseline, before any treatment was provided, patients rinsed with 10 ml sterile saline. After professional tooth cleaning the patients were instructed to abolish all tooth cleaning procedures for the subsequent 24 h. After this period, the rinsing procedure was repeated and the amount of de novo plaque was assessed. Three months after the initial periodontal therapy was completed the experiment was repeated. The microbiological evaluation of the rinsing samples was carried out by means of phase contrast microscopy and anaerobic culturing.

RESULTS

After treatment the amount of de novo plaque was less compared to before treatment, 0.40 and 0.65 respectively. Both before and after treatment more de novo plaque was present at sites with inflammation than at healthy sites. In order to evaluate the contribution of the numbers of salivary bacteria to the amount of de novo plaque formation an analysis was carried out for healthy sites. This analysis included only healthy sites as determined before treatment and the same sites after treatment. The results showed a significant reduction in the de novo plaque formation after treatment (0.49 before and 0.22 after treatment). Phase contrast microscopic evaluation showed that the number of bacteria in the rinsing samples after treatment was less than before treatment. After treatment also a reduction was found in the prevalence of Prevotella intermedia, Tannerella forsythensis and Peptostreptococcus micros in the rinsing samples.

CONCLUSION

The present study confirms the observation in the literature that the periodontal condition is of major importance in the rate of de novo plaque formation. In addition, the results suggest that the number of bacteria in the saliva may play a role.

Effects of periodontitis and smoking on the microbiota of oral mucous membranes and saliva in systemically healthy subjects

BACKGROUND/AIM

To examine the differences in the proportions of 40 bacterial species in samples from eight oral soft-tissue surfaces and saliva in systemically healthy adult subjects with and without periodontitis and in smokers and nonsmokers.

METHODS

Saliva and microbial samples were taken from eight oral soft-tissue surfaces in 229 systemically healthy subjects stratified by periodontal and smoking status. Subjects included 84 periodontally healthy and 145 periodontitis individuals. Of these, there were 182 nonsmokers and 47 smokers. Soft-tissue samples were taken using a "buccal brush" and saliva was taken by expectoration. All samples were individually evaluated for their content of 40 bacterial species using checkerboard DNA-DNA hybridization. The percentage of total DNA probe count was determined for each species at each sample location and averaged across subjects. The significance of differences among the proportions of the 40 test species at different sample locations was sought in these populations using the Kruskall-Wallis test and adjusted for multiple comparisons.

RESULTS

When stratified for periodontal status or smoking status, microbial profiles at most sites did not differ significantly. Generally, periodontal pathogens were found at higher levels on the soft tissues of periodontitis subjects than in periodontally healthy subjects, and at higher levels in smokers than nonsmokers. Few significant differences were found, although trends in the populations were noted.

CONCLUSIONS

Small differences in the proportions of bacterial species were observed on soft tissues and in saliva comparing periodontally healthy and periodontitis subjects. Somewhat greater differences between smokers and nonsmokers were found; however, these were not statistically significant.

Susceptibilities of different Actinobacillus actinomycetemcomitans strains to lactoperoxidase-iodide-hydrogen peroxide combination and different antibiotics

Actinobacillus actinomycetemcomitans has an important aetiological role in localized juvenile periodontitis and in progressive periodontitis in adults. A. actinomycetemcomitans is found mainly in periodontal pockets but also in whole saliva, a potential transmission medium. It is sensitive to peroxidase-halide systems, but the differences between periodontitis associated clinical isolates and type strains are unclear. The sensitivities of these 2 strain groups to lactoperoxidase (LP)-iodide (I(-))-hydrogen peroxide (H(2)O(2)) combinations were investigated, and the sensitivities were compared with the susceptibilities to four antibiotics. There was great variation between the sensitivities of different strains, but the 2 strain groups responded similarly. The LP (75 microg)-I(-) (100 nmol)-H(2)O(2) (1000 nmol) combination produced a similar degree of inhibition as 2 microg ampicillin. The LP-I(-) system might be a potential antimicrobial agent against A. actinomycetemcomitans transmission via saliva.

Salivary microbiota levels in relation to periodontal status, experience of caries and miswak use in Sudanese adults

OBJECTIVES

The purpose of the present investigation was to assess the salivary levels of 25 oral bacteria in relation to periodontal status and experience of caries, and to compare the levels of these bacteria between habitual miswak and toothbrush users in adult Sudanese subjects.

MATERIAL AND METHODS

The study subjects consisted of 56 individuals with age range 19-53 years (mean 35.2 years) and included 30 miswak and 26 toothbrush users. The periodontal status and presence of dental caries were assessed clinically. Whole saliva was collected from all subjects, and the levels of 25 selected bacterial species in saliva were assessed by the checkerboard DNA-DNA hybridization method using whole genomic DNA probes.

RESULTS

A high percentage of the subjects had detectable levels (> or = 105 bacterial cells) of several bacterial species in saliva. Between 12% and 16% of the subjects showed high (> or = 106 cells) salivary levels of the periodontitis-associated bacteria A. actinomycetemcomitans, P. melaninogenica, P. intermedia, C. rectus and E. corrodens, whereas only two (3.6%) and four (7.1%) subjects had high levels of P. gingivalis and F. nucleatum, respectively. There were no significant differences in the levels of all or most bacterial species by age group, gender or periodontal status. Presence of > or = 105 L. acidophilus bacterial cells in saliva was associated with high caries scores (p = 0.02). There were significantly higher levels of A. actinomycetemcomitans, P. melaninogenica, C. rectus, P. micros, V. parvula, S. mutans, S. anginosus, A. israelii, C. sputigena, and C. gingivalis, and significantly lower levels of P. intermedia, F. nucleatum, S. sputigena, E. corrodens, L. acidophilus, S. sanguis, S. salivarius, S. oralis, and S. mitis in the miswak than in the toothbrush group.

CONCLUSIONS

: The findings suggest that miswak may have a selective inhibitory effect on the level of certain bacteria in saliva, particularly several oral streptococci species. This is the first report that the checkerboard DNA-DNA hybridization method can be useful for assessing the levels of a wide range of bacterial taxa in saliva.

Oral colonization by anaerobic bacteria during childhood: role in health and disease

Anaerobes constitute a significant part of bacterial communities in human mouths. Their ability to colonize and survive in the environment, where remarkable changes occur during early childhood, is fundamental for oral homeostasis. However, relatively little is known of the time of colonization and succession of anaerobic species in the oral cavity. This article presents an up-to-date review on the development of the oral anaerobic microflora in respect to age, and in addition, considers some aspects of the role of oral anaerobes in health and disease.

Oral ecology and person-to-person transmission of Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis

The ecological characteristics of the oral cavity are dissimilar for A. actinomycetemcomitans and for P. gingivalis, as judged by differences in their colonization preferences and patterns, associations with periodontal disease parameters, relationships with the subgingival microbiota and the type of periodontitis and their clonal persistence in the oral cavity. These features also suggest that as a periodontal pathogen, A. actinomycetemcomitans is different from P. gingivalis. Probably in most infected individuals, low levels of A. actinomycetemcomitans can persist for years in equilibrium with the host and the resident oral microbiota. However, it is well established that A. actinomycetemcomitans can cause disease in some individuals or in some circumstances when the regulatory mechanisms are unable to maintain homeostasis in the ecosystem. Elevated A. actinomycetemcomitans proportions of the biota can be regarded as a sign of ecological imbalance, leading to increased risk of periodontal destruction. There is also evidence showing elevated pathogenic potential of certain A. actinomycetemcomitans clones. Although A. actinomycetemcomitans seems to be relatively rarely transmitted between cohabiting adults, transmission can occur to periodontally healthy children of A. actinomycetemcomitans-positive parents. Parents and children may share factors that promote successful oral colonization of A. actinomycetemcomitans, or the window of opportunity is in childhood. Therefore, to prevent parent-child transmission of A. actinomycetemcomitans, bacterium-positive parents of young children are optimal targets for enhanced information and treatment. In selected populations, screening for specific clones of A. actinomycetemcomitans has been employed in prevention of peridontitis. Future research aiming at finding the reasons which cause the changes in the oral homeostasis to allow the growth of A. actinomycetemcomitans may give insight into novel prevention strategies for A. actinomycetemcomitans-associated periodontitis. Compared with A. actinomycetemcomitans, P. gingivalis shows a different pattern of coexistence with the host. In periodontal health or in children, P. gingivalis is absent or only rarely detected. When present, P. gingivalis is commonly recovered in high numbers from dentitions exhibiting inflamed periodontitis and poor oral hygiene. Contrary to A. actinomycetemcomitans, the data on the vertical transmission of P. gingivalis are limited. The major infection route of P. gingivalis seems to be between adults, indicating that P. gingivalis commonly colonizes in an established oral microbiota. These characteristics suggest that the degree of tolerance between P. gingivalis and the host is inferior to that between A. actinomycetemcomitans and the host. It appears that the association of P. gingivalis with disease is a rule rather than an accidental incident. On these grounds, it seems that the host-P. gingivalis relationship approaches antibiosis. Since P. gingivalis infection is related to a typical periodontal eco-pathology, the susceptibility to person-to-person transmission of this pathogen may be controlled by periodontal treatment and emphasizing the significance of high standard oral hygiene.

The utility of whole saliva to detect the oral presence of periodontopathic bacteria

This study compared the presence of 6 periodontopathic bacteria in whole saliva and subgingival plaque of 202 subjects. The test bacteria were identified using a 16S rRNA-based PCR detection method. Each study subject contributed a whole saliva sample and a paper point sample pooled from the deepest periodontal pocket in each quadrant of the dentition. The kappa test revealed a fair agreement between the presence of Porphyromonas gingivalis, Prevotella intermedia, and Treponema denticola in whole saliva and periodontal pocket samples (kappa > 0.4). The McNemar test showed that the differences between sample types were due to a more frequent detection of the 3 organisms in whole saliva than in periodontal pocket samples (P < 0.01). Prevotella nigrescens also was detected more frequently in whole saliva than in periodontal pocket samples (P < 0.01; McNemar test). Although little agreement between samples was found for Actinobacillus actinomycetemcomitans and Bacteroides forsythus (kappa < or = 0.4), neither whole saliva nor pocket samples showed better detection for these 2 species (P < 0.01, McNemar test). The results indicate that whole saliva is superior to pooled periodontal pocket samples to detect P. gingivalis, P. intermedia, P. nigrescens, and T. denticola in the oral cavity. The detection of oral A. actinomycetemcomitans and B. forsythus with reasonably good accuracy may require both whole saliva and periodontal pocket samples.

Microbial complexes in subgingival plaque

It has been recognized for some time that bacterial species exist in complexes in subgingival plaque. The purpose of the present investigation was to attempt to define such communities using data from large numbers of plaque samples and different clustering and ordination techniques. Subgingival plaque samples were taken from the mesial aspect of each tooth in 185 subjects (mean age 51 +/- 16 years) with (n = 160) or without (n = 25) periodontitis. The presence and levels of 40 subgingival taxa were determined in 13,261 plaque samples using whole genomic DNA probes and checkerboard DNA-DNA hybridization. Clinical assessments were made at 6 sites per tooth at each visit. Similarities between pairs of species were computed using phi coefficients and species clustered using an averaged unweighted linkage sort. Community ordination was performed using principal components analysis and correspondence analysis. 5 major complexes were consistently observed using any of the analytical methods. One complex consisted of the tightly related group: Bacteroides forsythus, Porphyromonas gingivalis and Treponema denticola. The 2nd complex consisted of a tightly related core group including members of the Fusobacterium nucleatum/periodonticum subspecies, Prevotella intermedia, Prevotella nigrescens and Peptostreptococcus micros. Species associated with this group included: Eubacterium nodatum, Campylobacter rectus, Campylobacter showae, Streptococcus constellatus and Campylobacter gracilis. The 3rd complex consisted of Streptococcus sanguis, S. oralis, S. mitis, S. gordonii and S. intermedius. The 4th complex was comprised of 3 Capnocytophaga species, Campylobacter concisus, Eikenella corrodens and Actinobacillus actinomycetemcomitans serotype a. The 5th complex consisted of Veillonella parvula and Actinomyces odontolyticus. A. actinomycetemcomitans serotype b, Selenomonas noxia and Actinomyces naeslundii genospecies 2 (A. viscosus) were outliers with little relation to each other and the 5 major complexes. The 1st complex related strikingly to clinical measures of periodontal disease particularly pocket depth and bleeding on probing.

Eradication of Actinobacillus actinomycetemcomitans from the oral cavity in adult periodontitis

Eradication of Actinobacillus actinomycetemcomitans from the oral cavity seems to be a prerequisite for successful therapeutic outcome in patients periodontally infected with the organism. In view of the limited number of subgingival samples obtained in recent studies one cannot conclude, however, whether eradication has actually been achieved. In the present study clinical and microbiological parameters were monitored in 10 adult patients with A. actinomycetemcomitans-associated periodontitis during successive non-surgical and adjunctive metronidazole plus amoxicillin (or ciprofloxacin) (AB) therapy. In every patient, 13 extracrevicular samples and subgingival samples from the deepest site of every tooth present were selectively cultivated for A. actinomycetemcomitans. The organism was isolated in 47 +/- 29% subgingival and 64 +/- 31% extracrevicular samples. Six weeks following subgingival scaling, A. actinomycetemcomitans was detected in 37 +/- 30% subgingival and 55 +/- 38% extracrevicular samples (n.s.). Three months after antibiotic therapy, the organism was recovered from only 1 patient. At baseline, 7.5 +/- 4.2% sites had a probing pocket depth (PPD) > or = 7 mm. This proportion dropped to 2.3 +/- 2.4% after scaling (p < 0.05) and to 0.3 +/- 0.4% after AB (p < 0.05). The proportion of sites with clinical attachment loss (CAL) > or = 6 mm dropped from 23.3 +/- 13.3% to 17.7 +/- 13.4% (p < 0.05) and to 16.8 +/- 14.6%. Statistical analysis revealed that the organism was strongly related, at baseline, to PPD > or = 7 mm (odds ratio 9.8, p < 0.001). Six weeks after scaling, the organism was associated with CAL > or = 6 mm (odds ratio 1.8, p = 0.02). After scaling, high counts of A. actinomycetemcomitans in excess of 10(4) CFU/ml significantly interfered with attachment gain of > or = 2 mm (odds ratio 0.24, p = 0.001). Based on the present findings, eradication of A. actinomycetemcomitans seems to be possible with adjunctive antibiotic treatment. Elimination of the organism after scaling was only weakly associated with clinical improvement.

Periodontitis patient and the spouse: periodontal bacteria before and after treatment

Suspected periodontal pathogens can be transmitted between spouses. The treatment response may be unsuccessful in periodontitis patients, if the spouse harbors these bacteria. The aim of the present 6-month follow-up study was to clarify whether the microbiological treatment outcome of periodontitis patients is related to the detection of suspected periodontal pathogens in the saliva of the spouse. 10 patients with advanced periodontitis and their spouses were included in the study. The patients received mechanical periodontal treatment and 500 mg metronidazole systemically 2x a day for 7 days. The presence of visible plaque, gingival bleeding after probing, suppuration, supragingival and subgingival calculus and pocket depths were assessed at baseline and 1 and 6 months after treatment. Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia/Prevotella nigrescens, Campylobacter rectus and Peptostreptococcus micros were cultured from pooled subgingival samples from the patients and from salivary samples from the spouses at corresponding occasions. Periodontal conditions in the patients improved after treatment as determined by the significantly lower values of clinical variables 1 and 6 months after treatment compared to those at baseline. However, the re-emergence of periodontal bacteria after treatment of the patients was not related to the concurrent detection of the respective bacteria in the saliva of the spouses. In this study design, it seemed that the salivary bacterial load in the spouse was of minor importance for the microbiological treatment outcome of the patient.

Can one acquire periodontal bacteria and periodontitis from a family member?

Recent findings suggest that two major periodontal pathogenes, Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis, are transmitted among family members. The authors discuss the evidence of person-to-person transmission of periodontal bacteria, the significance of saliva as a vehicle of transmission and the methods of verifying clonal similarity of bacterial strains obtained from family members. The authors also discuss the prophylactic and therapeutic implications of the person-to-person spread of periodontal bacteria.

Experimental gingivitis in periodontitis-susceptible subjects

The purpose of this study was to evaluate clinical, microbiological, and gingival crevicular fluid (GCF) profiles in periodontitis-resistant and periodontitis-susceptible subjects during 4 weeks of experimental gingivitis. Experimental groups of similar ages were defined as gingivitis controls (GC; n = 10) and history of rapidly progressive periodontitis (RPP; n = 10), respectively. Prior to baseline, all subjects achieved good plaque control (plaque index (P1I) approximately 0) and gingival health (gingival index (GI) = 0), and had probing depths < or = 4 mm on experimental teeth. For 4 weeks after baseline, oral hygiene around maxillary 2nd premolar and 1st molar teeth was inhibited by a plaque guard. The plaque guard was removed weekly for GCF sampling to determine interleukin (IL)-1 beta and prostaglandin (PG)E2 amounts by ELISAs. In addition, P1I, GI, probing depth, and gingival recession measurements were made. Subgingival plaque darkfield microscopy and DNA probe analysis also were performed. Results indicated that clinical signs of inflammation, microbiological patterns and GCF profiles progressed similarly in both groups. However, plaque accumulated more rapidly in the susceptible subjects. P1I in RPP at 4 weeks was 2.1 +/- 0.1 compared to 1.5 +/- 0.2 in GC, with an incidence of P1I > of 100% versus 50%, respectively (logistic regression; p < 0.0001). Hence, the clinical, microbiological and host factors selected for this study were unrelated to previous susceptibility to periodontitis when evaluated in the experimental gingivitis model. However, the increased rate of plaque accumulation, following thorough plaque removal, in RPP patients suggests a potential factor in disease recurrence in these susceptible subjects.

Likelihood of transmitting Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis in families with periodontitis

This study examined the frequency of spouse-to-spouse and parent-child transmission of the periodontal pathogens Actinobacillus actinomycetemcomitans (124 subjects in 47 families) and Porphyromonas gingivalis (78 subjects in 31 families). The two test organisms were recovered from subgingival and tongue surface specimens using established microbiological techniques. Arbitrarily primed polymerase chain reaction (AP-PCR) was used to genetically characterize isolates of the test species. The probability of isolating identical AP-PCR types of A. actinomycetemcomitans and P. gingivalis in family members by chance was estimated from the AP-PCR genotype distribution of the two species among unrelated individuals. A probability of 5% or less for occurrence by chance alone suggests intra-familial transmission. With a bacterium-positive spouse, A. actinomycetemcomitans revealed inter-spousal transmission in 4/11 (36%) married couples and P. gingivalis in 2/10 (20%) married couples. Parent-child transmission of A. actinomycetemcomitans took place in 6/19 (32%) families. P. gingivalis was not transmitted from parent to child in any of the study families. The intra-familial transmission of A. actinomycetemcomitans and P. gingivalis may in part explain a familial pattern of periodontitis and may have important prophylactic and treatment implications.

Increased acetaldehyde production by mouthwashings from patients with oral cavity, laryngeal, or pharyngeal cancer

Excessive ethanol consumption is associated with an increased risk of oral cavity, laryngeal, and pharyngeal cancer. Ethanol has been shown to be oxidized to acetaldehyde by microflora of the upper respiratory tract. As a highly toxic and reactive compound, acetaldehyde of microbial origin has been incriminated as a possible carcinogenic factor behind alcohol-associated malignancies of the upper respiratory tract. The aim of the present in vitro study was to compare the acetaldehyde producing capacity of mouthwashings obtained from patients with oral cavity, laryngeal, or pharyngeal cancer to that of mouthwashings from controls. The ability of mouthwashings to produce acetaldehyde from ethanol in vitro was determined by incubating them in closed vials containing various concentrations of ethanol (0-44 mM) at 37 degrees C for 1 hr. Acetaldehyde formed during the incubation was then analyzed by head space gas chromatography. Acetaldehyde production by mouthwashings increased with raising ethanol concentration in both groups. Acetaldehyde production by mouthwashings from patients with oral cavity, laryngeal, or pharyngeal cancer was significantly (p < 0.01) higher than that of the controls. Increased acetaldehyde formation from ethanol in the upper respiratory tract could thus contribute to the pathogenesis of alcohol-associated oral cavity, laryngeal, and pharyngeal cancers.

Source of suspected periodontal pathogens re-emerging after periodontal treatment

To clarify the source of re-emerging periodontal pathogens after treatment, we compared the ribotypes of Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia/Prevotella nigrescens group and Campylobacter rectus before and after treatment in 7 periodontitis patients and in 6 of the spouses. The patients harbored A. actinomycetemcomitans, P. gingivalis, P. intermedia/P. nigrescens group or C. rectus in their subgingival or salivary samples before treatment. The respective bacterial species were not detected 1 month after treatment, but reappeared by 6 months later. When available, 4 random colonies of each of the 4 species were isolated from both subgingival and salivary samples at each sampling occasion, the isolates were subcultured, identified and typed applying pheno- and genotypic intraspecies characterization methods. Altogether 90 strains of A. actinomycetemcomitans, P. gingivalis, P. intermedia/P. nigrescens group and C. rectus were available from 2, 3, 2 and 4 patients, respectively. The pre- and post-treatment ribotypes of A. actinomycetemcomitans-, P. gingivalis- and P. intermedia/P. nigrescens group-isolates were identical in all respective patients. The pre- and post-treatment ribotypes of C. rectus were identical in 1 of 4 patients, whereas 2 patients harbored a previously not detected post-treatment ribotype and 1 patient harbored the initial and a previously not detected post-treatment ribotype. To study the possibility that periodontitis patients may acquire strains from the spouse after treatment, isolates of A. actinomycetemcomitans, P. gingivalis, P. intermedia/P. nigrescens group and C. rectus (n = 95) from the patients' spouses were ribotyped and compared with those of the patients. The patient exhibited his own post-treatment ribotypes, different from those of the spouse, of A. actinomycetemcomitans and P. gingivalis in 1 couple and of P. intermedia/P. nigrescens group and C. rectus in 1 couple. In the 2 patients who harbored a previously not detected post-treatment ribotype of C. rectus, one patient shared the new ribotype with the spouse, whereas the other one did not. Although an exogenous source cannot be fully ruled out, the patient's own oral flora seems to be the main source of re-emerging periodontal pathogens after treatment.