Different Stages Of Periodontal Disease Research Articles

Variability of salivary analytes under daily conditions and their implications for periodontitis biomarkers

IntroductionRecent studies have identified inflammatory mediators as potential biomarkers for monitoring or diagnosing periodontitis. However, the brief half-life of these mediators, coupled with their variability among different individuals and across different stages of periodontal disease, may limit their reliability as biomarkers.MethodsIn this study, we assessed the concentration profile of salivary biomarkers (IL-6, IL-8, and total protein) through repeated measurements within the same day and across different days in 79 patients exhibiting various states of periodontal health: intact periodontium, stable periodontitis, and active periodontitis. Additionally, we explored how daily variations, such as the interval between toothbrushing and eating, impact the levels of these salivary biomarkers and their diagnostic efficacy for periodontitis activity.ResultsOur results showed high salivary levels of IL-6 and total proteins in periodontitis patients (p < 0.001), with detection ability reflected by an Area Under the Receiver Operating Characteristic Curve (AUC-ROC) ranging between 0.709 and 0.852. Conversely, IL-8 levels were higher in patients with intact periodontium (p < 0.001), with an AUC-ROC for periodontitis detection between 0.671 and 0.815. Daily activities such as toothbrushing and eating influenced the levels of specific analytes, particularly total proteins (p < 0.001), but this did not affect their ability to detect periodontal disease activity. The highest measurement agreement, assessed by Intraclass Correlation Coefficients (ICC), was found for IL-6, with no significant differences in agreement between same-day and different-day measurements.ConclusionsOur study demonstrated consistency in the repeated measurements of salivary analytes, both within the same day and across different days, except for salivary total protein levels. These analytes exhibited variability within a range that did not undermine their effectiveness as biomarkers for periodontal disease.

The effect of systemic Isotretinoin on salivary tissue inhibitors of metalloproteinases 1 and 2 and salivary flow rate in periodontal disease.

AimsTo evaluate and compare changes in salivary flow rate and salivary levels of TIMP-1 and TIMP-2 in individuals taking oral Isotretinoin (INN) with those who do not take INN. To assess the variation in TIMP-1 and TIMP-2 as well as salivary flow rate observed at different stages of periodontal disease in comparison to those observed in the case of healthy periodontium.Materials and methodsAn examiner-blind case-control study involving 180 human adults divided into six groups based on their periodontal status. Clinical parameters, including pocket depth, clinical attachment level, and bleeding on probing were measured at six sites per tooth. Whole unstimulated saliva samples were collected from all subjects to evaluate salivary flow rate (SFR). Salivary TIMP-1 and TIMP-2 levels were detected using enzyme-linked immunosorbent assay (ELISA). Data were analyzed using IBM SPSS Software. The Kruskal Wallis test and Mann-Whitney U-tests were employed to verify any significant differences between the groups for all parameters. Multi-regression analysis was performed for each parameter tested in each group. All tests were compared at a significance level of 0.05.ResultsSFR was statistically significantly lower among all INN groups in comparison to the control groups (P < 0.001). TIMP-1 and TIMP-2 were significantly higher in all INN groups in comparison to the control groups, in both gingivitis cases (P = 0.004, P < 0.0001 respectively) and periodontitis cases (P < 0.0001).ConclusionAlthough INN reduces salivary flow rate, the findings of the present study revealed that it had an anti-inflammatory effect in periodontal biomarkers. Specifically, it was positively correlated with an elevation of salivary TIMP-1 and TIMP-2. Hence, INN might be a future additive medication to be further evaluated for the treatment of periodontal diseases.

A síndrome metabólica interfere na saúde bucal? Uma revisão integrativa

The aim of this study was to verify, through a review, the relationship between and conditions related to health, as well as the prevalence of these alterations. The search was carried out in 2020, considering the period from 2015 to 2019, in PubMed and Capes Journal Portal, using the descriptors metabolic syndrome (and) oral (or) oral consequences. The content was organized in a single textual corpus, building a Word Cloud and subsequently, the thematic-category content analysis proposed by Bardin was carried out. 16 articles were considered. In the word cloud of the corpus, the words: “ Sindrome Metabolica ” (Metabolic Syndrome), associacao ” (association) and from these: longitudinal, relacao e significativamente ” (longitudinal, relationship and significantly) were considered, as well as, “ perda dentaria ” (tooth loss), “ peridontite ” (periodontitis), “ saude bucal ” (oral health,) “ tabagismo ” (smoking), “ caries ” (cavities), “ obesidade ” (obesity) and “ idade ” (age) . Also bringing the word “ japones ” (Japanese), which refers to the most evaluated population. Three categories emerged: Oral Health , Risk Factors for Metabolic Syndrome and Quality of Life . An association was found between and the number of teeth affected by cavities, between different stages of periodontal disease with factors such as obesity, between the time since diagnosis of and the number of teeth remaining in the cavity and its impact on quality of life. It was also verified: association between and health condition, however, there are few studies, mainly in the western population, for the clarity of this association.

Bacteria and oral cavity: a new story to tell.

Periodontal diseases include a mild and reversible form named gingivitis (GI), and periodontitis (PD) that is the main cause of tooth loss in adults. GI, that affects gums and coronal junctional epithelium, as well as periodontitis, that is characterized by loss of connective tissue attachment, are caused by a persistent inflammatory response promoted by alteration of periodontal biofilm. The aim of the study was to test whether the prevalence of each species was associated with a particular clinical condition. Periodontal evaluation of 756 unrelated patients was performed by the Periodontal Screening and Recording (PSR) system. Subgingival samples were obtained from the site with the worst PSR score. A selection of eleven bacterial species was evaluated by quantitative real time PCR. Quantitative and qualitative analyses help to better understand the microbial changes associated with different stages of periodontal disease.

Evaluation of active matrix metalloproteinase-8 (aMMP-8) chair-side test as a diagnostic biomarker in the staging of periodontal diseases

ObjectiveThere is a need for a reliable complementary diagnostic tool that ideally helps to screen, differentiate sites, activities of and predict future periodontal tissue destruction. The purpose of this cross-sectional study was to investigate the screening and prevention potential of the chair-side/point-of-care (PoC) diagnostic test of salivary active matrix metalloproteinase-8 (aMMP-8) levels at different stages of periodontal disease and periodontal health. Material & methods80 individuals were included in this study; 18 with periodontitis stage 3 (P-Stage III), 19 with periodontitis stage-4 (P-Stage IV), 21 with gingivitis, and 22 with clinically healthy periodontium (H). The aMMP-8 levels in GCF and saliva were analyzed by chairside point-of-care aMMP-8 lateral flow immunotest and also by a time-resolved immunofluorescence assay (IFMA). ResultsThe sensitivity of the chair-side/PoC test was 83.9 % while specificity was 79.2 %. The aMMP-8 IFMA levels in GCF were significantly higher in P-Stage IV group than P-Stage III, gingivitis and healthy groups (p = 0.01, p = 0.001, p = 0.00, respectively). Moreover, P-Stage III and gingivitis groups had significantly higher aMMP-8 IFMA levels than the healthy group (p < 0.05). ConclusionThe aMMP-8 chair-side test showed promising results in its ability to recognize and predict the inflammatory status even at the very initial/early stages. aMMP-8 chair-side test could be a valuable adjunctive diagnostic and preventive tool to conventional clinical methods in detecting periodontal disease.

Association between isotretinoin (Roaccutanne) use and changes in periodontal clinical parameters and MMP-8 and MMP-9 salivary levels.

Aims: to evaluate changes in clinical periodontal parameters, salivary levels of MMP-8 and MMP-9, in individuals taking Isotretinoin (INN), and compare with individuals not taking the medication and to compare findings among different stages of periodontal disease and healthy periodontium. Material and methods: A case-control study was conducted with a total of 180 human adults divided into six groups. Clinical parameters, including pocket depth (PD), clinical attachment level (CAL), and bleeding on probing (BOP) were measured at six sites per tooth. Whole unstimulated saliva samples were collected from all subjects to detect salivary level of MMP-8, MMP-9 using Enzyme-linked immunosorbent assay (ELISA). Data were analyzed using IBM SPSS Software. Kruskal Wallis test and Mann-Whitney U-tests were used to test any significant differences in any of the groups on all parameters. Pearson Chi-square test was used to compare the distribution of categorical responses across the study groups. All tests were compared at a significance level of 0.05. Results: In Gingivitis cases, INN group was found to have significantly less BOP (P < 0.0001). In Periodontitis cases, INN group showed significant difference in BOP (P < 0.0001). MMP-8 and MMP-9 were significantly lower among Periodontitis cases taking INN compared to the same group not taking the medication (P < 0.0001). Conclusion: INN assists in reducing clinical and biological signs of inflammation related to periodontal disease progression. INN may be a future additive medication to be further evaluated for treating periodontal disease.

Oral Microbiome Signatures in Diabetes Mellitus and Periodontal Disease

Disturbances in the oral microbiome are associated with periodontal disease initiation and progression and diabetes mellitus (DM), but how this contributes to the cause-and-effect relationship between periodontal disease and DM is poorly understood. We examined the bacterial composition in plaque samples from 128 South Africans with periodontal disease across glycemic statuses using 16S rDNA sequencing of regions 2, 3, 4, 6-7, 8, and 9. Of the 9 phyla identified, Firmicutes, Proteobacteria, Bacteroidetes, Fusobacteria, and Actinobacteria made up >98%. Fusobacteria and Actinobacteria were significantly more abundant in subjects with diabetes, while Proteobacteria were less abundant. However, in the presence of gingival bleeding and DM, as compared with DM without gingival bleeding, Actinobacteria were markedly reduced while Bacteroidetes were more abundant. In contrast, no differences in Actinobacteria or Bacteroidetes abundance were observed between DM with and without pocket depth (PD) ≥4 mm. At the genus level, similar changes in relative abundance were observed in the presence of DM and periodontal disease. Our findings remained in conditional logistic regression models adjusted for age, sex, waist circumference, and the 5 most dominant phyla. For example, Actinobacteria significantly increased the odds of diabetes by 10% in subjects with gingival bleeding, while Fusobacteria increased this odd by 14%; yet, among subjects with PD ≥4 mm, Fusobacteria decreased the odds of DM by 47%. Our findings have confirmed the alterations in the composition of the oral microbiota across glycemic statuses as well as different stages of periodontal disease. However, it is not clear whether these differences were the consequence of hyperglycemia or the presence of periodontal diseases. Therefore, we recommend further investigations in a longitudinal study design.

Reliability of Periodontal Pathogens and Human Cathelicidine Ll-37 in the Prediction of the Different Stages of Periodontal Disease

Reliability of Periodontal Pathogens and Human Cathelicidine Ll-37 in the Prediction of the Different Stages of Periodontal Disease

Dental Pathology of the Iberian Lynx ( Lynx pardinus), Part II: Periodontal Disease, Tooth Resorption, and Oral Neoplasia.

The Iberian lynx is an endangered felid that has been subject to an intensive, ongoing conservation program to save it from extinction. Identification of dental pathologies could play an important role in the survival of this endangered species. The prevalence of periodontal bone loss, tooth resorption, and oral neoplasia was evaluated in this species. Skulls of 88 adult specimens of the Iberian lynx ( Lynx pardinus) from the Doñana Biological Station (EBD-CSIC), Seville, Spain, were examined macroscopically and full-mouth dental radiographs of all specimens were performed. Different stages of periodontal disease were identified in 81.3% of teeth. Approximately two-thirds (64.8%) of the specimens examined had at least 1 tooth affected by stage 3 or 4 periodontal disease. Maxillary and mandibular incisor teeth accounted for a majority (59.4%) of teeth affected by stage 3 or 4 periodontal disease. Tooth resorption affected 12 teeth (0.63% of evaluated teeth) in 6 skull specimens (6.8% of skulls evaluated). Five of the teeth with resorptive lesions were detected on 1 skull specimen. Six teeth (50%) of those affected by tooth resorption were incisor teeth. Only 1 (1.1%) adult specimen showed signs of oral neoplasia. Our study concluded that there is a high prevalence of periodontal disease that could lead to impaired hunting ability, as well as may represent a threat to overall health and subsequent survival of this endangered species. The extremely low prevalence of tooth resorption in L pardinus could open new pathways in the discovery on the pathogenesis of tooth resorption in felids.

Quantification of mast cells in different stages of periodontal disease.

Mast cells are mononuclear cells originating from bone marrow. They produce various biologically active substances, which allow them to actively participate in immune and inflammatory processes associated with periodontal disease. The study focused on distribution and density of mast cells in healthy gingiva as well as in different stages of periodontal disease. The material used for this purpose was gingival biopsies taken from 96 patients classified into 4 groups: healthy gingiva, gingivitis, initial and severe periodontal disease. Toluidine blue staining according to Spicer was utilized for identifying mast cells. Basing on our study, the density of mast cells in the gingival tissue increases with the progression of the infection, which means they are more numerous in gingivitis compared to healthy gingiva, as well as in periodontal disease compared to gingivitis. Increase in the number of mast cells in the infected gingiva can be correlated with an increased influx of inflammatory cells from blood circulation into the gingival stroma, as well as with the collagen lysis, since these cells produce substances with collagenolytic potential. Based on the distribution of mast cells, it could be concluded that in the evolution of periodontal disease there are significant dynamic alterations in migration and localization of these cells.

Epigenetic Regulation of TNFA Expression in Periodontal Disease

Tumor necrosis factor-α (TNF-α) plays a central role in the molecular pathogenesis of periodontal disease. However, the epigenetic regulation attributable to microbial and inflammatory signals at the biofilm-gingival interface are poorly understood. In this study, the DNA methylation alteration within the TNFA promoter in human gingival biopsies from different stages of periodontal disease is investigated and the regulatory mechanism of TNFA transcription by DNA methylation is explored. Gingival biopsies were obtained from 17 patients with chronic periodontitis (CP) and 18 periodontally healthy individuals. Another 11 individuals participated in an experimentally induced gingivitis study, and gingival biopsies were collected at the baseline, induction, and resolution phase. To confirm that TNFA promoter methylation modulated TNFA transcription, THP.1 cells were treated with a DNA methyltransferase inhibitor, 5-Aza-2-deoxycytidine (5-Aza-2dC), and an RAW294.7 cell line transfected with a TNFA promoter-specific luciferase reporter system with or without methylation was used. In gingival biopsies from individuals with severe CP, two individual cytosine-guanine dinucleotides (CpG sites) within the TNFA promoter (at -163 and -161 bp) displayed increased methylation in CP samples compared to those with gingival health (16.1% ± 5.1% versus 11.0% ± 4.6%, P = 0.02 and 19.8% ± 4.1% versus 15.4% ± 3.6%, P = 0.04, respectively). The methylation level at -163 bp was inversely associated with the transcription level of TNFA (P = 0.018). However, no significant difference in the TNFA promoter methylation pattern was observed in samples biopsied during the induction or resolution phase of experimentally induced gingivitis, which represented a reversible periodontal lesion. THP.1 cells treated with 5-Aza-2dC demonstrated a time-dependent increase in TNFA messenger level. It was also found that the luciferase activity decreased 2.6-fold in a construct containing an in vitro methylated TNFA promoter when compared to the unmethylated insert (P = 0.03). Although the biopsy samples represented a mixed cell population, the change in promoter methylation status in chronic periodontal disease suggested that DNA methylation may be an important regulatory mechanism in controlling TNFA transcriptional expression in periodontal disease.

Design of a multiple drug delivery system directed at periodontitis

Periodontal disease is highly prevalent, with 90% of the world population affected by either periodontitis or its preceding condition, gingivitis. These conditions are caused by bacterial biofilms on teeth, which stimulate a chronic inflammatory response that leads to loss of alveolar bone and, ultimately, the tooth. Current treatment methods for periodontitis address specific parts of the disease, with no individual treatment serving as a complete therapy. The present research sought to demonstrate development of a multiple drug delivery system for stepwise treatment of different stages of periodontal disease. More specifically, multilayered films were fabricated from an association polymer comprising cellulose acetate phthalate and Pluronic F-127 to achieve sequential release of drugs. The four types of drugs used were metronidazole, ketoprofen, doxycycline, and simvastatin to eliminate infection, inhibit inflammation, prevent tissue destruction, and aid bone regeneration, respectively. Different erosion times and adjustable sequential release profiles were achieved by modifying the number of layers or by inclusion of a slower-eroding polymer layer. Analysis of antibiotic and anti-inflammatory bioactivity showed that drugs released from the devices retained 100% bioactivity. The multilayered CAPP delivery system offers a versatile approach for releasing different drugs based on the pathogenesis of periodontitis and other conditions.

Periodontal disease related to oxidative stress

The study evaluates oxidative stress (OS) in patients with different stages of periodontal disease (PD) and the influence of their smoking habits on OS. PD is related to connective tissue inflammation, which leads to deterioration of the supporting structures of the tooth. OS is a condition characterized by overproduction of free radicals (FR), which may be involved in PD, causing periodontal tissue damage and other related diseases. Study patients' were grouped as I-non smokers (n=45) and II-smokers (n=45); and consisted of patients with 3 PD stages: mild (1), moderate (2) and severe (3). As a control group, 30 healthy subjects (all non smokers) with no signs of PD were selected. FR levels were determined by the D-Roms test, total antioxidant capacity (AOC) was determined by the OXY-adsorbent test, (Diacron, Italy) and lipid peroxidation (LP) was determined by the fl uorometric method with thiobarbituric acid and its end product, malonyldialdehyde (MDA). OS was found in the periodontal tissue and serum of PD patients, with the highest level of FR in the severe stage (3) in non smokers (p<0.05) as well as smokers (p<0.01); AOC showed decreasing values from mild (1) to severe stage (3) of PD for smokers (p<0.05). LP in serum showed the highest level in severe stage (3) in both groups i.e., non smokers and smokers (p<0.05) compared to controls. Based on the obtained results, we may conclude that PD is related to OS and may either be a cause or a trigger for more accelerated OS. Cigarette smoking increased FR production and is a serious factor exacerbating further tissue damage in PD. These findings may contribute to possible use of efficient antioxidant agents as a preventive measure for PD and as a therapy for better disease outcome.

Gingival crevicular fluid can degrade Emdogain and inhibit Emdogain-induced proliferation of periodontal ligament fibroblasts

Emdogain (EMD), consisting mostly of amelogenin, is used in periodontal therapy to regenerate lost connective tissue. Emdogain is applied onto periodontally affected root surfaces, where it becomes exposed to proteolytic enzymes. In this study, we aimed to find out whether gingival crevicular fluid or matrix metalloproteinases (MMPs) could degrade EMD, and whether this degradation has consequences for in vitro cell proliferation. We studied the effects of 156 gingival crevicular fluid samples collected from subjects with different stages of periodontal disease and from healthy control subjects and the effects of MMP-1, -2, -8, -9, -13 and -14 on the degradation of EMD using EMD-embedded zymography. The effects of gingival crevicular fluid with or without EMD and the effects of amelogenin on the proliferation of cultured periodontal ligament fibroblasts were studied by cell proliferation enzyme-linked immunosorbent assay kit. Degradation of Emdogain induced by gingival crevicular fluid was greater in samples from all stages of periodontal diseases compared with healthy control samples. Of the MMPs studied, only MMP-2 and MMP-8 showed limited EMD-degrading activities. One hundred micrograms per millilitre of EMD increased proliferation of periodontal ligament fibroblasts on average by 24% (confidence interval 0.60-0.64) and at 200 microg/mL by 30% (confidence interval 0.62-0.68) compared with control fibroblasts (confidence interval 0.48-0.52). However, gingival crevicular fluid (10 microg/mL) together with 100 microg/mL EMD induced the proliferation only by 6% (confidence interval 0.51-0.55) and with 200 microg/mL EMD by 12% (confidence interval 0.54-0.58). Amelogenin at 200 microg/mL decreased the proliferation of periodontal ligament fibroblasts by 54% (confidence interval 0.22-0.25). We suggest that diseased gingival crevicular fluid containing various proteases leads to degradation of EMD and decreased proliferation of periodontal ligament fibroblasts.

Raised chondroitin sulphate WF6 epitope levels in gingival crevicular fluid in chronic periodontitis

To determine the levels of chondroitin sulphate (CS) WF6 epitope, recognized by WF6 monoclonal antibody, in gingival crevicular fluid (GCF) from different stages of periodontal disease and healthy periodontium, and to correlate those levels with clinical parameters. GCF samples, collected from 389 sites, were analysed for the WF6 epitope levels by the competitive enzyme-linked immunosorbent assay. The median WF6 epitope level was significantly higher in chronic periodontitis sites (n=185) than in healthy and gingivitis sites (n=204) (p<0.001), whereas the median levels did not significantly differ between healthy (n=65) and gingivitis sites (n=139). The median level in severe periodontitis sites (n=60) was significantly higher than that in moderate periodontitis sites (n=63) (p=0.019). Similarly, the median level in moderate periodontitis sites was significantly higher than that in slight periodontitis sites (n=62) (p=0.001). The WF6 epitope levels significantly correlated with probing depth (r=0.777, p=0.001) and loss of clinical attachment level (r=0.814, p=0.001). Elevated CS WF6 epitope levels in GCF are associated with severity of periodontitis. The WF6 antibody may therefore be clinically applied to monitor disease severity and progression.

A clinical study of plasminogen activator activity in gingival tissue in dogs with gingivitis and periodontitis

The aim of the present study was to evaluate plasminogen activator activity (PAA), tissue-type plasminogen activator (t-PA) antigen level and plasminogen activator inhibitor-1 (PAI-1) antigen in normal canine gingival tissue samples, gingivitis as well as in different stages of periodontal disease. Gingival tissue from 141 adult dogs were analysed spectrophotometrically in order to determine PAA. The tissues were also examined histopathologically. The Sulcus Bleeding Index was used to evaluate the active and inactive phase of periodontal disease. T-PA antigen as well as PAI-1 antigen level was measured by ELISA. There was a significant increase of PAA and t-PA antigen in samples from inflamed gingival tissue compared with normal gingival tissue, while PAI-1 antigen was not detected in either normal or inflamed gingiva. As the severity of periodontal disease was increasing, PAA and t-PA antigen values were significantly higher in periodontitis tissue sample groups, according to the pattern: gingivitis < early periodontitis < moderate periodontitis < severe periodontitis ( P < 0.001). PAA and t-PA antigen were increased in samples from the inflamed gingival tissue with higher Bleeding Index, (heavy bleeding > moderate bleeding > slight bleeding, P < 0.001). In conclusion, this study indicates that PAA and t-PA antigen level may be used to evaluate the evolution of periodontal disease in dog.

Analysis of human IgG and IgA subclass antibody-secreting cells from localized chronic inflammatory tissue.

The chronic inflammatory diseases in humans have been intensively investigated, however the immune mechanisms underlying diseases such as rheumatoid arthritis (RA), inflammatory bowel disease, and periodontal disease (PD) remain elusive. In this study, we have analyzed the distribution of IgM, IgG, and IgA secreting cells with emphasis on the IgG and IgA subclasses among mononuclear cell populations isolated from gingiva at different stages of PD. Surgically removed tissues were treated with Dispase to gently dissociate cells and the Ficoll-Hypaque gradient centrifugation was used to enrich for viable mononuclear cells rich in lymphocytes, macrophages, and plasma cells. The total numbers of plasma cells increased with the severity of disease. Immunofluorescence analysis showed that most Ig-containing cells were of the IgG isotype; however, significant numbers of IgA-positive cells but few IgM-positive cells were seen. This isolation procedure allowed analysis, at the single cell level, of the distribution of IgG and IgA subclasses of antibody-secreting cells with monoclonal antibodies to human IgG and IgA subclasses. For this, we selected four monoclonal anti-IgG subclass (anti-gamma 1, -gamma 2, -gamma 3, and -gamma 4) antibodies with no subclass cross reactivity for use in the enzyme-linked immunospot assay. Analysis of slight, moderate, and advanced stages of PD showed a progressive increase in spotforming cells (SFC) numbers, and the major isotype of SFC was IgG followed by IgA. The major IgG subclass SFC seen was IgG1 followed by IgG2 whereas similar numbers of IgG3 and IgG4 SFC were observed, a pattern also seen with cells from synovium of RA patients and in mitogen-triggered spleen and PBMC. In terms of the IgA subclass distribution, IgA1 predominated in moderate stages, whereas a selective increase in IgA2 SFC were seen in the more advanced stage of PD. These results show that significant numbers of viable plasma cells/Ig-secreting cells can be isolated from inflamed gingival tissues. Further, careful analysis has shown that IgG subclass responses in gingiva are similar to those found in synovia of RA subjects, and in stimulated PBMC and spleen. However, it should be noted that the number of IgG4- and IgA2-secreting cells increased in the advanced stage of PD.

Bacteriology of periodontal disease in the cat

Subgingival plaque samples were obtained from 32 cats showing different stages of periodontal disease. Correlations were sought between gingival index scores and the prevalence of various microbial groups, and between microbial populations found in sites designated as most-affected and least-affected within individual cats. The tendency with higher gingival index scores, and with the most-affected sites, was toward a microbial population composed to a greater extent of anaerobic Gram-negative rods. The most common organism was an anaerobic Gram-negative rod in the black-pigmented Bacteroides group that was biochemically similar to B. gingivalis but had catalase activity. The black-pigmented Bacteroides group and Peptostreptococcus anaerobius were found in increasing numbers with increasingly severe periodontal disease. Pasteurella multocida was isolated from most samples and appeared to decrease in numbers with increasing periodontal disease.