A Review of the Role of Probiotic Supplementation in Dental Caries

Dental diseases are among the common health issues experienced around the world. Dental caries is one of the most predominant oral diseases worldwide. Major factors associated with caries development include poor oral hygiene, the content of specific carbohydrates in the diet, dental biofilm formation, the cariogenic microbial load, reduction in salivary flow, insufficient fluoride exposure, gingival recession, genetic factors, and lack of personal attention to one's dental health. Several preventive measures have been implemented to reduce the risk of the development of caries. Probiotics are live microbes that when administered in suitable amounts confer health benefits on the host; they are recognized as potential adjunct therapeutic agents for several diseases. The present manuscript summarizes recent findings on the role of probiotics in dental caries prevention and the possible mechanisms of probiotic effects. Review of the literature indicates the regular consumption of probiotic products significantly reduced the risk of caries by inhibiting cariogenic bacteria and enriching commensal microbes in the oral cavity. Buffering the salivary pH, production of bacteriocin and enzymes (dextranase, mutanase, and urease), the capacity of competing for the adhesion and colonization on tooth surfaces are the possible mechanisms behind the beneficial effect of probiotics. Further studies are necessary to address the efficacy of long-term probiotic supplementation on the control of dental diseases and the influence of childhood probiotic supplementation on the risk of caries development.

Bacterial Biofilm Morphology on a Failing Implant with an Oxidized Surface: A Scanning Electron Microscope Study

This case report provided a unique opportunity to investigate the extent of microbiota infiltration on the oxidized implant surface that has been compromised by peri-implantitis. Scanning electron microscopic analysis confirmed the etiologic role of the bacteria on the loss of supporting structure and the difficulty in complete removal of bacterial infiltration on the implant surface. This case report emphasizes the need to perform definitive surface decontamination on failing dental implants prior to a regeneration procedure.

Isolation and identification of Porphyromonas spp. and other putative pathogens from cats with periodontal disease

The purpose of this study was to evaluate the subgingival microbiota and determine the most prevalent periodontal pathogens implicated in feline periodontal disease and to correlate these findings with the clinical periodontal status. Subgingival microbiological samples were taken under sedation from 50 cats with clinical signs of periodontal disease. Pooled paper point samples from 4 selected subgingival sites were cultured on blood agar and on Dentaid-1 medium. Suspected pathogens were identified, subcultured, and preserved. The association between the microbiological findings and the clinical status was studied using correlation coefficients (CC). In addition, cats were stratified in subgroups according to presence of putative pathogens, and comparisons were carried out using unpaired t-test. Three bacterial species were frequently detected including Porphyromonas gulae (86%), Porphyromonas circumdentaria (70%) and Fusobacterium nucleatum (90%). The mean proportion of total flora was high for P. gulae (32.54%), moderate for P. circundentaria (8.82%), and low for F. nucleatum (3.96%). Among the clinical variables, tooth mobility was correlated (CC > 0.50, p < 0.001) with recession, pocket depth, attachment level, gingival index, and calculus index (CC = 0.29, p = 0.04) as well as with total bacterial counts (CC = 0.38, p = 0.006). Cats with more than 10% of P. gulae showed significantly more mobility (p = 0.014) and recession (p = 0.038), and a tendency for deeper probing pocket depths (p = 0.084) and attachment loss (p = 0.087). The results from this cross-sectional study confirmed that P. gulae is the most relevant pathogen in periodontal disease in cats.

No association between A actinomycetemcomitans or P gingivalis and chronic or aggressive periodontitis diagnosis

OBJECTIVES

Only a few studies have attempted to detect differences in microbiologic profiles of patients with chronic periodontitis (CP) and aggressive periodontitis (AgP). The aim of this analysis was to assess if clinical diagnosis or other subject factors showed association with the presence of Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis in a cohort of periodontitis patients.

METHOD AND MATERIALS

Statistical analysis for association between bacterial detection and clinical diagnosis was performed on a total of 267 consecutive periodontitis cases diagnosed with either CP (n = 183) or AgP (n = 84). All subjects had microbiologic samples collected from the four deepest pockets and analyzed by nested polymerase chain reaction.

RESULTS

A actinomycetemcomitans was detected in 54% and 48% of CP and AgP subjects, respectively. A slightly higher detection of P gingivalis was found in CP (67% ) compared with AgP (52%) cases. The detection of P gingivalis was associated with older age (P = .002), less disease severity (P = .015), and IL6-1480 genotypes (P = .026), while A actinomycetemcomitans was associated with IL6-1480 genotypes (P = .001).

CONCLUSION

Detection of known periodontopathogenic bacteria is not able to discriminate different forms of periodontitis.

Microbiota of Exposed Root Surfaces After Fluoride, Chlorhexidine, and Periodontal Maintenance Therapy: A 3-Year Evaluation

BACKGROUND

Fluoride and chlorhexidine (CHX) are state-of-the-art preventive measures for remineralizing teeth and for preventing plaque accumulation. The aim of this study was to examine the effects of fluoride and CHX varnishes on root caries and microbiota located on root surfaces.

METHODS

Thirty-three patients from a periodontal maintenance program, having at least one tooth with gingival recession in each quadrant, participated in this study. One tooth per quadrant was assigned randomly to the control group or to one of the test groups that were treated with fluoride varnish, 1% CHX, or 40% CHX. The varnish treatment and the tooth cleaning were repeated every 3 months. Clinical examinations were performed at baseline and once a year for 3 years. Caries status and oral hygiene indices were evaluated clinically. The total cultivable microbiota and percentage of Mutans streptococci (MS), Actinomyces (ACC), and lactobacilli (LB) were analyzed.

RESULTS

Oral hygiene was improved greatly during the course of the study. The percentage of MS, ACC, and LB of the total cultivable microbiota revealed a statistically significant reduction between baseline and final examination for each of the four groups.

CONCLUSION

Professional tooth cleaning alone at 3-month intervals might be as effective in reducing MS, ACC, and LB as adjunctive treatment with fluoride or chlorhexidine.

Plaque development in relation to the periodontal condition and bacterial load of the saliva

AIM

To investigate the influence of the oral bacterial load on plaque development in various groups of periodontitis patients and in healthy subjects.

MATERIAL AND METHODS

This study included subjects with a healthy periodontium, a healthy reduced periodontium after treatment, an inflamed reduced periodontium after treatment and untreated periodontitis. At the start of the study, subjects were instructed to rinse with 10 ml reduced transport fluid (RTF) for 10 s in order to evaluate the oral bacterial load. The microbiological evaluation included anaerobe culture and phase-contrast microscopy. Next, the amount of plaque and the clinical condition were evaluated. Thereafter, all supragingival plaque was removed and patients were instructed to refrain from all oral hygiene procedures for 19 h. Subsequently, the rinsing procedure and the evaluation of the amount of plaque were repeated.

RESULTS

The amount of plaque that developed in 19 h was significantly higher in the untreated periodontitis group as compared with the two healthy groups. In case of an inflamed reduced periodontium, sites with deep pockets developed more plaque in 19 h than sites with shallow pockets. The number of bacteria present in the rinsing samples of the two inflamed groups was considerably higher than of the two periodontally healthy groups. A significant correlation was found between the bleeding index at intake and the plaque index at 19 h. No correlations were found between gingival recession and the bacterial counts at intake, and the plaque index at 19 h.

CONCLUSION

The present findings support the concept that the periodontal condition is the dominating factor in relation to the rate of plaque formation. The number of bacteria present in the oral cavity as ascertained by means of a rinsing sample does not seem to play a role.

The influence of membrane exposure on the outcomes of guided tissue regeneration: clinical and microbiological aspects

The aim of the present study was to evaluate the influence of membrane exposure on guided tissue regeneration (GTR). Thirty patients with 2-wall or 3-wall intraosseous defects were treated with GTR. Periodontal index, gingival index, bleeding on probing, probing depth, clinical attachment level and recession were assessed at the baseline examination, as well as immediately prior to and six months after GTR. The numbers of Porphyromonas gingivalis and Actinobacillus actinomycetemcomitans on the retrieved expanded polytetrafluoroethylene (e-PTFE) membranes were assessed using polymerase chain reaction. The results showed that 26.3% of the membrane exposure sites had zero attachment gain. The membrane exposure sites tended to achieve a smaller clinical attachment gain and had significantly greater marginal tissue recession ( p = 0.006). In addition, the exposed membranes harbored significantly more A. actinomycetemcomitans than the non-exposed membranes (p = 0.029). In conclusion, membrane exposure resulted in a poor GTR outcome. The amount of A. actinomycetemcomitans on the exposed membrane may be a major contributing factor to the outcome of GTR.

GTR treatment of intrabony defects in patients with early-onset and chronic adult periodontitis

Young, systemically healthy subjects may suffer from early-onset forms of periodontitis characterized by the presence of localized deep vertical bony defects. The aim of this study was to compare the healing response after guided tissue regeneration (GTR) treatment of similar intrabony defects in patients affected by early-onset and chronic adult periodontitis. Twenty systemically healthy, nonsmoking subjects were enrolled in the study; 10 were affected by early-onset periodontitis (EOP) and 10 by chronic adult periodontitis (CAP). In each subject, only one deep vertical bony defect (intrabony component > 4 mm, probing attachment level > or = 8 mm) was treated according to the principles of GTR therapy with titanium-reinforced e-PTFE membranes. At the time of the surgery and at the 1-year follow-up, a microbiologic test for the identification of the main periodontopathogens was performed in each of the treated sites. There was no statistically significant difference at 1 year in the amount of clinical attachment gain (P = .4), reduction of probing pocket depth (P = .3), or increase in gingival recession (P = 1.0) between EOP and CAP patients. The 1-year microbiologic results demonstrated the complete disappearance of the putative periodontopathogens from all surgically treated sites in both patient groups. The results of the study demonstrated that deep intrabony defects in patients with EOP can be successfully treated by means of GTR procedures and that the suppression of periodontopathogens under threshold values can be maintained for at least 1 year, provided that the patient is enrolled in a maintenance program consisting of recalls for professional tooth cleaning and reinforcement of self-performed oral hygiene measures at 1-month intervals.

Adhesion of Porphyromonas gingivalis strains to cultured epithelial cells from patients with a history of chronic adult periodontitis or from patients less susceptible to periodontitis

BACKGROUND

The present study aimed to explain the interindividual variation in periodontitis susceptibility by differences in the initial adhesion rate of Porphyromonas gingivalis to the pocket epithelium of these individuals, and/or by inter-P. gingivalis strain differences in association capacity (adhesion and internalization).

METHODS

Adhesion assays were performed on epithelial monolayers (cultured in vitro from pocket epithelium belonging to patients who were less or more susceptible to chronic adult periodontitis) using 11 genetically different clinical strains of P. gingivalis.

RESULTS

Both the disease category (less susceptible versus susceptible) and the interstrain variation were found to have a significant effect (both P <0.05) on the initial bacterial association. The chronic adult periodontitis group showed significantly more association of P. gingivalis when compared to less susceptible patients (4.2 x 10(6) versus 3.5 x 10(6)). Also, the interstrain variation was significant, with strains Pg 4 and 5 representing the least and best associating bacteria (1.8 x 10(6) colony forming units for Pg 4, 9 x 10(6) for Pg 5).

CONCLUSIONS

These results indicate that periodontitis susceptibility is influenced by both the interindividual differences in pocket epithelium (allowing more adhesion of P. gingivalis) or by the strain type by which the patient is infected (intra-species differences in adhesion capacity).

Serum IgG reactivity to subgingival bacteria in initial periodontitis, gingivitis and healthy subjects

BACKGROUND/AIMS

Established periodontal diseases may be associated with antibody responses to periodontal pathogens, but it is not known at which stage of disease this antibody response is initiated. This study aimed to characterize the host systemic response in initial periodontitis, gingivitis, and periodontal health, to evaluate whether elevated serum antibodies to subgingival species could be detected in initial periodontitis.

METHOD

Human systemic immune response were evaluated to 40 subgingival bacterial species in 16 healthy, 21 gingivitis, 11 initial periodontitis and 5 progressing recession adults. Subjects had minimal periodontal attachment level (AL) loss at baseline. Disease categories were determined after 12 months monitoring at three-month intervals. Increased AL loss > or = 1.5 mm (disease activity) at interproximal sites defined initial periodontitis, recession was characterized by AL loss at buccal sites. Serum IgG antibodies were evaluated semi-quantitatively by immunoblot from blood taken at baseline, active and final visits.

RESULTS

No antibody was detected from 55% of reactions. When detected, levels were below those reported for advanced periodontitis subjects. There were no major differences in serum antibody levels between healthy, gingivitis and initial periodontitis subjects, despite differences in the subgingival microbiota. Serum antibodies for more species were detected in recession subjects, compared with the other study subjects. No changes in antibody levels were detected between baseline, active, and final visits. No systematic association between species colonization and presence of systemic antibody was observed.

CONCLUSIONS

This study did not detect differential elevation of mean serum antibody levels in initial periodontitis subjects, suggesting that serum antibody levels are not sensitive risk markers for initial periodontitis.

Microbiota of health, gingivitis, and initial periodontitis

This study compared the subgingival microbiota in periodontal health, gingivitis and initial periodontitis using predominant culture and a DNA probe, checkerboard hybridization method. 56 healthy adult subjects with minimal periodontal attachment loss were clinically monitored at 3-month intervals for 12 months. More sites demonstrated small increments of attachment loss than attachment gain over the monitoring period. Sites, from 17 subjects, showing > or = 1.5 mm periodontal attachment loss during monitoring were sampled as active lesions for microbial analysis. Twelve subjects demonstrated interproximal lesions, and 5 subjects had attachment loss at buccal sites (recession). Cultural studies identified Bacteroides forsythus, Campylobacter rectus, and Selenomonas noxia as the predominant species associated with active interproximal lesions (9 subjects), whereas Actinomyces naeslundii, and Streptococcus oralis, were the dominant species colonizing buccal active sites. A. naeslundii, Campylobacter gracilis, and B. forsythus (at lower levels than active sites) were the dominant species cultured from gingivitis (10 subjects). Health-associated species (10 subjects) included Streptococcus oralis, A. naeslundii, and Actinomyces gerencseriae. DNA probe data identified higher mean levels of B. forsythus and C. rectus with active (7 subjects) compared to inactive periodontitis sites. Porphyromonas gingivalis and Actinobacillus actinomycetemcomitans were detected infrequently. Cluster analysis of the cultural microbiota grouped 8/9 active interproximal lesions in one subcluster characterized by a mostly gram-negative microbiota, including B. forsythus and C. rectus. The data suggest that B. forsythus C. rectus and S. noxia were major species characterizing sites converting from periodontal health to disease. The differences in location and microbiota of interproximal and buccal active sites suggested that different mechanisms may be involved in increased attachment loss.

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.

A comparison of IgG antibody reactive with Bacteroides forsythus and Porphyromonas gingivalis in adult and early-onset periodontitis

Recent work has indicated that Bacteroides forsythus and Porphyromonas gingivalis are significant local risk factors for periodontitis. Several reports find that both organisms are frequently associated with periodontitis lesions and often are present together. We have previously shown that early-onset periodontitis patients seropositive for P. gingivalis have less attachment loss than seronegative patients. In this study, we determined serum IgG antibody concentrations reactive with B. forsythus in adult and early-onset periodontitis patients using an ELISA and used P. gingivalis in the same populations as a positive control. The results for P. gingivalis were consistent with previous work and indicated that 47%, 36%, and 33% of adult, generalized early-onset, and localized juvenile patients were seropositive, respectively. Mean serum IgG concentrations for the three groups were 5.36 microg/ml, 5.65 microg/ml, and 5.44 microg/ml for adult, generalized early-onset, and localized juvenile patients, respectively. In contrast, for B. forsythus only 11%, 14%, and 10% of adult, generalized early-onset, and localized juvenile patients were seropositive, with mean serum IgG concentrations of 0.46 microg/ml, 0.46 microg/ml, and 0.47 microg/ml, respectively. This suggests that B. forsythus is either poorly immunogenic or less invasive than P. gingivalis. If most patients fail to mount an immune response to B. forsythus and it is invasive, it may explain why this organism is a risk factor for disease.

The influence of titanium abutment surface roughness on plaque accumulation and gingivitis: short-term observations

The roughness of intraoral hard surfaces plays an important role in bacterial adhesion and colonization. Earlier studies have shown that rough surfaces accumulate up to 25 times more subgingival plaque than do smooth sites. In the present study, the influence of surface smoothing was studied. In six partially edentulous patients waiting for a fixed prosthesis supported by endosseous titanium implants, four titanium abutments with different surface roughness were randomly placed. After 1 month of intraoral exposure, subgingival plaque samples from each abutment were compared within each patient by means of differential phase-contrast microscopy. After 3 months, supragingival and subgingival plaque samples were taken from all abutments for differential phase-contrast microscopy and culturing. Probing depth, recession, and bleeding upon probing were scored at the same visit. Differential phase-contrast microscopy showed that subgingivally, only the two roughest abutments harbored spirochetes after 1 month. After 3 months, subgingivally, the composition of the flora showed little variation on the different abutment types, although spirochetes were only noticed around the roughest abutments. Anaerobic culturing resulted in comparable amounts of colony-forming units for all abutment types, both supragingivally and subgingivally. Subgingivally, the microbiologic composition did not show major interabutment differences. Clinically, small differences in probing depth were observed. The roughest abutment showed some attachment gain (0.2 mm) during 3 months, whereas all other abutments had an attachment loss ranging from 0.8 to greater than 1 mm. The results indicate that a reduction in surface roughness (less than a roughness of 0.2 micron) had no major effect on the microbiologic composition, supragingivally or subgingivally. These observations indicate the existence of a threshold roughness below which no further impact on the bacterial adhesion and/or colonization should be expected. However, clinical evaluation seems to indicate that a certain surface roughness is necessary for increased resistance to clinical probing.

The natural history of periodontal disease. The correlation of selected microbiological parameters with disease severity in Sri Lankan tea workers

The purpose of this study was to assess the prevalence of A. actinomycetemcomitans, Porphyromonas gingivalis and Prevotella intermedia, and their association with periodontal disease states in a population sample from Sri Lanka. Based on clinical parameters, a total of 536 sites in 268 male Sri Lankan tea workers were categorized as healthy, or showing gingivitis only, moderate or advanced periodontitis. Bacterial samples were obtained from all sites and the three target bacteria identified by indirect immunofluorescence. P. intermedia, P. gingivalis and A. actinomycetemcomitans were found in 76%, 40% and 15% of the subjects, respectively. Of the 536 periodontal sites, 10.5% were categorized with "no disease", 14% "gingivitis only": 59% with moderate and 16% with advanced periodontitis. The prevalence of P. gingivalis and P. intermedia was significantly higher in sites with moderate and advanced periodontitis than in sites with no disease or gingivitis only. A. actinomycetemcomitans was not found in healthy sites, but occurred with equal frequency in sites with gingivitis, moderate and advanced periodontitis. The association between these three bacteria and periodontal diseases in Sri Lankan tea laborers was similar to that described for other non-industrialized and industrialized countries.

Site-related streptococcal attachment to buccocervical tooth surfaces. A correlative micromorphologic and microbiologic study

Scanning electron (SEM) microscopy of epoxy replicas made from dental impressions has shown that in buccal gingival recession the root surfaces are devoid of cementum, leaving the dentin exposed. In this study replication techniques were applied to correlate the micromorphology of the buccocervical region with early streptococcal attachment. The subjects were 27 healthy young adults. The buccocervical surfaces of all the premolars were meticulously cleaned. The subjects fasted for 2 h before impression-taking. Replicas were made from impressions in hydrophilic A-silicone, and streptococcal attachment was visualized by light microscopy of mitis-salivarius agar replicas incubated anaerobically for 48 h. The surface micromorphology was documented by SEM of corresponding epoxy replicas. Colonization only 2 h after cleaning was very sparse. Sites with healthy or inflamed gingivae had markedly different colonization patterns in the sulcular region. In 4 subjects with a total of 12 sites where gingival recession, undetected clinically, was disclosed by SEM, representative colonies were retrieved and identified microbiologically to species level. Two healthy sites per subject were also sampled. Streptococcus mutans and S. sobrinus were identified from eight sites with exposed root dentin. S. oralis predominated on the enamel surfaces. The method offers a valuable complement to in situ and in vitro microbiologic studies of exposed dentin and a novel technique for sampling clinical isolates of streptococci.

Guided tissue regeneration in the treatment of infrabony defects on maxillary premolars. A pilot study

The present study evaluated clinically and radiographically the short-term results of the healing of infrabony defects at maxillary premolars treated according to guided tissue regeneration (GTR). 9 patients with bilateral presence of infrabony defects with or without furcation involvements at maxillary premolars were selected. At baseline assessments of plaque and gingival indices, bleeding, probing pocket depth and attachment level, and furcation measurements were recorded. Conventional radiographs were obtained in a way that assured a reproducible projection geometry. One premolar was randomly treated with GTR and the contralateral with open debridement. Clinical and radiographic examinations were performed again 6 months postoperatively. The bone tissue changes were assessed by means of conventional radiographs and subtraction images. Sites treated by both procedures demonstrated an improvement of gingival conditions and a reduction of pocket depths. A statistically significant attachment gain was obtained for the test (mean 1.2 mm), but not for the control sites (mean 0.6 mm). The differences, though, were not significant between the test and control sites. Limited improvement in furcation closure was recorded. The radiographic examination demonstrated loss of bone tissue in four sites treated with GTR. The findings suggest that the regeneration of the periodontal soft and bone tissues was not significantly enhanced with the GTR therapy.

Periodontal pathogens in the shallow pockets of immigrants from developing countries

The aim of this study was to examine the distribution of typical periodontitis-associated microorganisms in refugees arriving from non-industrialized countries, and to relate the presence of these organisms to the periodontal condition of the subjects. Thirty males between 35-44 years of age were surveyed. Dental plaque, calculus, gingivitis, loss of attachment, and probing depths were recorded for all surfaces. A total of 90 microbiological samples were taken with paper points from mesial sites of teeth 16, 36 and 41. Microbiological test sites were grouped by probing depths and loss of attachment. Only 16.8% of all surfaces had probing depths > 3 mm, although 90.7% of surfaces had loss of attachment > 1 mm. Twenty-one sites with obvious periodontal destruction (PD > 3 mm, LA > 2 mm) showed the greatest recovery of Porphyromonas gingivalis (66.7%). However, 51 sites with minimal periodontal disease (PD < or = 3 mm, LA < 2 mm) and with no gingival recession also showed a relatively high detection frequency of P. gingivalis (34.1%). Twenty-four of these samples came from 12 patients with no pockets > 5 mm and with less than 10% of all sites yielding pockets > 3 mm. The detection frequencies of Prevotella intermedia (91.6%), Bacteroides forsythus (25.0%), Wolinella spp. (33.3%) and Actinobacillus actinomycetemcomitans (50.0%) were similar in these sites compared with periodontitis sites. Morphologically distinct isolates, from 19 individuals positive for A. actinomycetemcomitans, were serotyped by indirect immunofluorescence.(ABSTRACT TRUNCATED AT 250 WORDS)

The effects of different levels of dietary sucrose on root caries subsequent to gingivectomy in conventional rats infected with Actinomyces viscosus M-100

Three groups of weanling, Sprague-Dawley-derived rats were inoculated with Actinomyces viscosus M-100 and fed powdered diet containing either 67%, 5%, or 0% confectioner's sugar. Two further groups were fed diet containing 5% confectioner's sugar and inoculated with Streptococcus sobrinus 6715 or S. sobrinus 6715 plus A. viscosus M-100. The most coronal 1 mm of gingiva was removed from maxillary and mandibular right molar quadrants (gingivectomy), and the animals re-inoculated following gingivectomy. The animals were killed 64 days following gingivectomy, and the lingual surface of mandibular first molar roots was measured for exposed root-surface area and root caries. In the groups of rats infected with A. viscosus M-100, root caries area was significantly greater in the group fed diet containing 67% confectioner's sugar. Sucrose level did not significantly affect the amount of exposed lingual first molar root area regardless of whether the tooth had been subjected to a gingivectomy. In the groups of rats receiving diet containing 5% confectioner's sugar, there were no significant differences in root caries area or exposed root-surface area, regardless of the infection status of the animals. In the rat model presented here, a high level of dietary sucrose was a necessary condition for the initiation of root caries in the absence of other readily fermentable carbohydrates.