TRAF3IP2-IL-17 Axis Strengthens the Gingival Defense against Pathogens.

Recent genome-wide association studies have suggested novel risk loci associated with periodontitis, which is initiated by dysbiosis in subgingival plaque and leads to destruction of teeth-supporting structures. One such genetic locus was the tumor necrosis factor receptor-associated factor 3 interacting protein 2 (TRAF3IP2), a gene encoding the gate-keeping interleukin (IL)-17 receptor adaptor. In this study, we first determined that carriers of the lead exonic variant rs13190932 within the TRAF3IP2 locus combined with a high plaque microbial burden was associated with more severe periodontitis than noncarriers. We then demonstrated that TRAF3IP2 is essential in the IL-17-mediated CCL2 and IL-8 chemokine production in primary gingival epithelial cells. Further analysis suggested that rs13190932 may serve a surrogate variant for a genuine loss-of-function variant rs33980500 within the same gene. Traf3ip2 null mice (Traf3ip2-/-) were more susceptible than wild-type (WT) mice to the Porphyromonas gingivalis-induced periodontal alveolar bone loss. Such bone loss was associated with a delayed P. gingivalis clearance and an attenuated neutrophil recruitment in the gingiva of Traf3ip2-/- mice. Transcriptomic data showed decreased expression of antimicrobial genes, including Lcn2, S100a8, and Defb1, in the Traf3ip2-/- mouse gingiva in comparison to WT mice prior to or upon P. gingivalis oral challenge. Further 16S ribosomal RNA sequencing analysis identified a distinct microbial community in the Traf3ip2-/- mouse oral plaque, which was featured by a reduced microbial diversity and an overabundance of Streptococcus genus bacteria. More P. gingivalis was observed in the Traf3ip2-/- mouse gingiva than WT control animals in a ligature-promoted P. gingivalis invasion model. In agreement, neutrophil depletion resulted in more local gingival tissue invasion by P. gingivalis. Thus, we identified a homeostatic IL-17-TRAF3IP2-neutrophil axis underpinning host defense against a keystone periodontal pathogen.

Distinct Microbial Signatures between Periodontal Profile Classes.

Precise classification of periodontal disease has been the objective of concerted efforts and has led to the introduction of new consensus-based and data-driven classifications. The purpose of this study was to characterize the microbiological signatures of a latent class analysis (LCA)-derived periodontal stratification system, the Periodontal Profile Class (PPC) taxonomy. We used demographic, microbial (subgingival biofilm composition), and immunological data (serum IgG antibody levels, obtained with checkerboard immunoblotting technique) for 1,450 adult participants of the Dental Atherosclerosis Risk in Communities (ARIC) study, with already generated PPC classifications. Analyses relied on t tests and generalized linear models with Bonferroni correction. Men and African Americans had higher systemic antibody levels against most microorganisms compared to women and Caucasians (P < 0.05). Healthy individuals (PPC-I) had low levels of biofilm bacteria and serum IgG levels against most periodontal pathogens (P < 0.05). Subjects with mild to moderate disease (PPC-II to PPC-III) showed mild/moderate colonization of multiple biofilm pathogens. Individuals with severe disease (PPC-IV) had moderate/high levels of biofilm pathogens and antibody levels for orange/red complexes. High gingival index individuals (PPC-V) showed moderate/high levels of biofilm Campylobacter rectus and Aggregatibacter actinomycetemcomitans. Biofilm composition in individuals with reduced periodontium (PPC-VI) was similar to health but showed moderate to high antibody responses. Those with severe tooth loss (PPC-VII) had significantly high levels of multiple biofilm pathogens, while the systemic antibody response to these microorganisms was comparable to health. The results support a biologic basis for elevated risk for periodontal disease in men and African Americans. Periodontally healthy individuals showed a low biofilm pathogen and low systemic antibody burden. In the presence of PPC disease, a microbial-host imbalance characterized by higher microbial biofilm colonization and/or systemic IgG responses was identified. These results support the notion that subgroups identified by the PPC system present distinct microbial profiles and may be useful in designing future precise biological treatment interventions.

Characterizing Microbiota from Sjögren's Syndrome Patients.

OBJECTIVE: To compare the oral microbiota of Sjögren's syndrome (SS) with that of healthy subjects (HS). METHODS: Supragingival and subgingival biofilm samples were collected from the mesial-buccal tooth surfaces of SS patients (n = 57) and age- and sex-matched HS (n = 53). Unstimulated saliva and 8 oral tissue samples were taken using a buccal brush. Caries and periodontal measures were recorded. All supragingival samples and a subgroup of 24 SS and 28 HS subgingival samples, as well as 32 SS and 11 HS saliva and oral tissue samples, were analyzed for their content of 41 bacterial species using checkerboard DNA-DNA hybridization. Mean levels (×105 ± SEM) and percentage of DNA probe counts of each species were determined for each sample site and averaged within subjects in the 2 clinical groups. Kruskal-Wallis tests, adjusting for multiple comparisons and cluster analysis, were used for soft tissue and microbial analysis, and the Mann-Whitney test was used to compare caries and periodontal measures. RESULTS: Mean (×105 ± SEM) total DNA probe counts in supragingival samples were significantly lower (P < 0.001) in the SS (13.3 ± .7) compared to the HS (44.1 ± 6.8) group. In supragingival samples, Veillonella parvula, Fusobacterium nucleatum ss vincenti, and Propionibacterium acnes were markedly elevated in the SS compared to the HS group in both mean (×105 ± SEM) and mean (± SEM) percentage DNA probe counts (P < 0.001). In subgingival samples of SS, V. parvula was significantly different compared to HS (P < 0.05). SS was characterized by high levels of purple and low levels of orange and red complexes. Cluster analysis of oral tissues and saliva demonstrated that the mean microbial profiles for SS patients and the HS group clustered separately. Active root caries (P < 0.003) and attachment loss were significantly higher (P < 0.029) in the SS group compared to the HS group. CONCLUSION: These findings indicate that saliva is a major controlling factor of intraoral biofilm. V. parvula may be a unique microbial biomarker for Sjögren's syndrome. KNOWLEDGE TRANSFER STATEMENT: The microbiome characterized for Sjögren's syndrome in salivary hypofunction is shown to be under stress and reduced. Veillonella parvula can be a possible identification of a biomarker for Sjögren's syndrome.

Association or Causation? Exploring the Oral Microbiome and Cancer Links.

Several epidemiological investigations have found associations between poor oral health and different types of cancer, including colorectal, lung, pancreatic, and oral malignancies. The oral health parameters underlying these relationships include deficient oral hygiene, gingival bleeding, and bone and tooth loss. These parameters are related to periodontal diseases, which are directly and indirectly mediated by oral bacteria. Given the increased accessibility of microbial sequencing platforms, many recent studies have investigated the link between the oral microbiome and these cancers. Overall, it seems that oral dysbiotic states can contribute to tumorigenesis in the oral cavity as well as in distant body sites. Further, it appears that certain oral bacterial species can contribute to carcinogenesis, in particular, Fusobacterium nucleatum and Porphyromonas gingivalis, based on results from epidemiological as well as mechanistic studies. Yet, the strength of the findings from these investigations is hampered by the heterogeneity of the methods used to measure oral diseases, the treatment of confounding factors, the study design, the platforms employed for microbial analysis, and types of samples analyzed. Despite these limitations, there is an overall indication that the presence of oral dysbiosis that leads to oral diseases may directly and/or indirectly contribute to carcinogenesis. Proper methodological standardized approaches should be implemented in future epidemiological studies as well as in the mechanistic investigations carried out to explore these results.

Commentary: Challenges and Opportunities for Women in Dental Research.

This commentary integrates and expands on the preceding articles in this issue that document and celebrate a century of women's achievements in the International Association for Dental Research (IADR). The increasing participation and leadership of women in dental and craniofacial research and within the IADR were viewed from the perspective of a changing culture of science. The steps that have been taken by the IADR to develop greater inclusiveness are acknowledged, and some of the challenges that remain are discussed in terms of obstacles that are most often social or cultural in origin. Comparisons are made across countries, and the social determinants that lead to differences in women's participation are described. Recommendations are made for developing strategies to change elements of our institutional cultures that have provided advantages to some groups of researchers more than to others. The unconscious biases and a lack of commitment to diversity, equity, and inclusion that limit the participation of members of some groups limit the progress and achievements of science in general.

Empowering Women Researchers in the New Century: IADR's Strategic Direction.

Gender inequality in science, medicine, and dentistry remains a central concern for the biomedical research workforce today. Although progress in areas of inclusivity and gender diversity was reported, growth has been slow. Women still face multiple challenges in reaching higher ranks and leadership positions while maintaining holistic success in these fields. Within dental research and academia, we might observe trends toward a more balanced pipeline. However, women continue to face barriers in seeking leadership roles and achieving economic equity and scholarship recognition. In an effort to evaluate the status of women in dental research and academia, the authors examined the role of the International Association for Dental Research (IADR), a global research organization, which has improved awareness on gender inequality. The goal of this article is to review five crucial issues of gender inequality in oral health research and academics-workforce pipeline, economic inequality, workplace harassment, gender bias in scholarly productivity, and work-life balance-and to discuss proactive steps that the IADR has taken to promote gender equality. Providing networking and training opportunities through effective mentoring and coaching for women researchers, the IADR has developed a robust pipeline of women leaders while promoting gender equality for women in dental academia through a culture shift. As knowledge gaps remained on the levels of conscious and unconscious bias and sexist culture affecting women advancement in academics, as well as the intersectionality of gender with race, gender identity, ability status, sexual orientation, and cultural backgrounds, the IADR has recognized that further research is warranted.

Sexual orientation of 46, XX patients with congenital adrenal hyperplasia: a descriptive review.

BACKGROUND: Congenital adrenal hyperplasia (CAH) consists of a group of diseases characterized by an enzyme deficiency, particularly 21-hydroxylase deficiency. The condition may present in the simple virilizing form or in the salt-wasting form, with varying degrees of genital ambiguity. The non-heterosexual orientation is used in gender studies fields and includes bisexual, homosexual, Lesbians, gays, bissexuals, transgender, intersex, and others. OBJECTIVE: The objective of this study was to evaluate the frequency of non-heterosexual orientation in patients with CAH, in an attempt to identify biological factors possibly associated with this occurrence. METHODS: This was a descriptive review of observational studies on the sexual orientation of patients with CAH published between 1985 and 2016, as listed in PubMed. RESULTS: Various studies have been performed to establish the relationship between CAH and non-heterosexual orientation. Non-heterosexual orientation is more prevalent in patients with more advanced Prader stages and those with the null and I2-splice genotype. CONCLUSION: The prevalence of homosexuality and bisexuality is greater in patients with CAH in relation to the general population.

Impact of a sepsis bundle in wards of a tertiary hospital.

BACKGROUND: Sepsis is a prevalent disease worldwide and still exhibits high rates of mortality. In the last years, many interventions aiming a positive impact on sepsis evolution have been studied. One of the main is the use of managed care protocols (sepsis bundles), which consist in systematization of diagnosis and treatment, such as standardization of antibiotics, collection of specific tests (cultures, lactate), and fluid replacement. Some studies have shown a reduction in hospital costs and lower mortality with the use of these tools. In the present study, we evaluated the impact of a sepsis bundle in wards of a tertiary hospital. METHODS: One hundred sixty-seven patients were retrospectively studied. The intervention was called "3-h bundle" and consisted of collecting lactate and cultures, start broad-spectrum antibiotics in the first hour of sepsis diagnosis, and volume replacement with crystalloid if hypotension or lactate ≥2 mmol/L. RESULTS: The overall mortality was 31.1%. Individuals who received the 3-h bundle showed a 44% lower mortality in comparison with who did not (25.6 vs. 45.7%; p = 0.01). Furthermore, the use of the sepsis bundle was independently correlated with lower mortality (OR = 0.175; CI = 0.04-0.64; p = 0.009). Therefore, a lower need for ICU admission and shorter length of stay in these units were observed in patients who received the intervention. CONCLUSION: The use of a sepsis protocol with systematic care in wards was associated with lower mortality, less need for ICU admission and shorter stay on these units.

The Salivary Microbiome and Oral Cancer Risk: a Pilot Study in Fanconi Anemia.

Fanconi anemia (FA) is a rare genetic disease characterized by chromosomal instability and impaired DNA damage repair. FA patients develop oral squamous cell carcinoma (OSCC) earlier and more frequently than the general population, especially after hematopoietic stem cell transplantation (HSCT). Although evidence of an etiological role of the local microbiome and carcinogenesis has been mounting, no information exists regarding the oral microbiome of FA patients. The aim of this study was to explore the salivary microbiome of 61 FA patients regarding their oral health status and OSCC risk factors. After answering a questionnaire and receiving clinical examination, saliva samples were collected and analyzed using 16S rRNA sequencing of the V3-V4 hypervariable region. The microbial profiles associated with medical and clinical parameters were analyzed using general linear models. Patients were young (mean age, 22 y) and most had received HSCT ( n = 53). The most abundant phyla were Firmicutes [mean relative abundance (SD), 42.1% (10.1%)] and Bacteroidetes [(25.4% (11.4%)]. A history of graft-versus-host disease (GVHD) ( n = 27) was associated with higher proportions of Firmicutes (43.8% × 38.5%, P = 0.05). High levels of gingival bleeding were associated with the genera Prevotella (22.25% × 20%), Streptococcus (19.83% × 17.61%), Porphyromonas (3.63% × 1.42%, P = 0.03), Treponema (1.02% × 0.28%, P = 0.009), Parvimonas (0.28% × 0.07%, P = 0.02) and Dialister (0.27% × 0.10%, P = 0.04). Finally, participants transplanted over 11 y ago showed the highest levels of Streptococcus (18.4%), Haemophilus (12.7%) and Neisseria (6.8%). In conclusion, FA patients that showed poor oral hygiene harbored higher proportions of the genera of bacteria compatible with gingival disease. Specific microbial differences were associated with a history of oral GVHD and a history of oral mucositis.

Levels of Candidate Periodontal Pathogens in Subgingival Biofilm.

In recent years, several new periodontal taxa have been associated with the etiology of periodontitis. A recent systematic review provides further support for the pathogenic role of 17 species/phylotypes. Thus, the aim of this study was to assess the prevalence and levels of these species in subjects with generalized chronic periodontitis (GChP; n = 30), generalized aggressive periodontitis (GAgP; n = 30), and periodontal health (PH; n = 30). All subjects underwent clinical and microbiological assessment. Nine subgingival plaque samples were collected from each subject and analyzed for their content of 20 bacterial species/phylotypes through the RNA-oligonucleotide quantification technique. Subjects from the GChP and GAgP groups presented the highest mean values for all clinical parameters in comparison with the PH group (P < 0.05). Subjects with GChP and GAgP showed significantly higher mean levels of Bacteroidetes sp. human oral taxon (HOT) 274, Fretibacterium sp. HOT 360, and TM7 sp. HOT 356 phylotypes, as well as higher mean levels of Filifactor alocis, Fretibacterium fastidiosum, Porphyromonas gingivalis, Tannerella forsythia, and Selenomonas sputigena species than PH subjects (P < 0.05). GAgP subjects presented higher mean levels of TM7 sp. HOT 356 and F. alocis than GChP subjects (P < 0.05). A significantly higher mean prevalence of Bacteroidales sp. HOT 274, Desulfobulbus sp. HOT 041, Fretibacterium sp. HOT 360, and Fretibacterium sp. HOT 362 was found in subjects with GChP and GAgP than in PH subjects. Mean levels of P. gingivalis (r = 0.68), T. forsythia (r = 0.62), F. alocis (r = 0.51, P = 0.001), and Fretibacterium sp. HOT 360 (r = 0.41) were correlated with pocket depth (P < 0.001). In conclusion, Bacteroidales sp. HOT 274, Desulfobulbus sp. HOT 041, Fretibacterium sp. HOT 360, Fretibacterium sp. HOT 362, and TM7 sp. HOT 356 phylotypes, in addition to F. alocis, F. fastidiosum, and S. sputigena, seem to be associated with periodontitis, and their role in periodontal pathogenesis should be further investigated.

HIV/AIDS-Associated Cryptococcosis in Portugal Spanning the Pre- to Post-HAART Era: A Retrospective Assessment at the Genotypic Level Based on URA5-RFLP.

Cryptococcosis caused by the fungus Cryptococcus neoformans is an opportunistic mycosis, infecting mainly immunodepressed individuals. Molecular epidemiology studies of cryptococcosis in Europe are limited. This paper presents a retrospective study of cryptococcosis in 105 cryptococcal isolates from two hospitals in Lisbon, Portugal, among HIV/AIDS patients, from 1991 to 2007. Among these patients, the number of cases of cryptococcosis increased from 5.1 to 6.9 cases per year from the pre- to post-highly active antiretroviral therapy (HAART) era. As expected, the median age of the patients increased, from 32 (mean: 33 ± 8) to 39 (mean: 41 ± 10) years, and the ratio of male to female patients remained high (7.7 and 7.6, respectively). Strain genotyping based on restriction fragment length polymorphism of the orotidine monophosphate pyrophosphorylase (URA5-RFLP) gene showed that, in general, the relative frequencies of the genotypes VNI-IV are similar to those from other European countries. These frequencies were, respectively, for the pre- and post-HAART periods: 41.7 and 43.5 % for VNI; 2.8 and 17.4 % for VNII; 38.9 and 30.4 % for VNIII; 16.7 and 7.2 % for VNIV and 0 and 1.4 % for VGII. Some apparent although statistically insignificant differences among these values were observed between both periods. The genotypic frequencies were not also statistically different according to the patients' gender or age range. Of note are the high proportion of VNIII isolates (common in Europe) and the high increase in the frequency of the VNII genotype in the post-HAART. Ultimately, these results may have implications in disease therapy, management and control.

Immunological profile of periapical endodontic infections from HIV- and HIV+ patients.

AIM: To evaluate CD4(+) CD28(+) and CD8(+) T-cell genes and the gene expression of IFN-γ, TNF-α, IL-1-ß, IL-17A, IL-10, CCL-2/MCP-1, CCL-4, CCL-5 (RANTES), CXCR4, CCR5 and RANKL from cells in the periapical interstitial fluid from root canal infections in healthy patients (HIV-) and HIV-positive individuals (HIV+). METHODOLOGY: Subjects included 20 HIV- and 23 HIV+ patients referred to the School of Dentistry at the Universidade Federal de Minas Gerais (Belo Horizonte, MG, Brazil). Almost all HIV+ patients were undergoing highly active antiretroviral therapy (HAART). Clinical samples were taken from teeth with pulp necrosis, and no patients had acute periapical symptoms at the time of the appointments. After cleaning and drying, 3 paper points were introduced into the root canal, passing passively through the root apex (2 mm) into the periapical tissues for 1 min. The samples were collected immediately after root canal cleaning and 7 days later (restrained root canal bacterial load) to characterize those gene expressions using real-time PCR. RESULTS: Significantly higher levels of CD4(+) CD28(+) and CD8(+) T cells in teeth with restrained bacterial loads (second collection) compared with the first collection were observed in both HIV- and HIV+ samples. In HIV- patients, an increase in IL-10 and CXCR4 expression was demonstrated as well as a decrease in pro-inflammatory cytokines such as RANKL, IFN-γ, IL1-ß and CCL5. However, in HIV+ patients an increase in cytokines IFN-γ, IL-1-ß, TNF-α and IL-17A, and chemokines CCL-2, CXCR4 and CCR5 were observed. The chemokine CCL-5 was not detected in HIV+ individuals. CONCLUSIONS: These findings suggest that after reducing the root canal bacterial load in HIV- individuals an anti-inflammatory response is generated whilst in HIV+ patients a pro-inflammatory response is sustained in the periapical area.

Gingival crevicular fluid levels of interferon-γ, but not interleukin-4 or -33 or thymic stromal lymphopoietin, are increased in inflamed sites in patients with periodontal disease.

OBJECTIVE: To investigate the hypothesis that levels of interferon (IFN)-γ and interleukin (IL)-4, as well as the newer cytokines IL-33 and thymic stromal lymphopoietin (TSLP), in gingival crevicular fluid (GCF) samples differ from sites of patients at various clinical stages of periodontal disease and controls. BACKGROUND: Periodontal diseases result from the complex interplay between pathogenic bacteria and the host's immune responses. Several inflammatory mediators, such as IFN-γ and IL-4, have been detected in GCF samples in patients with periodontitis, but the results are mostly contradicting due to the lack of uniformity and collection of sites and methods of analysis. MATERIAL AND METHODS: GCF samples were collected from sites with different clinical characteristics (healthy, gingivitis and periodontitis sites) from periodontally healthy ( n = 14), plaque-induced gingivitis (n = 17) and chronic periodontitis (n = 11) subjects. The GCF samples were analyzed for the frequency of detection and levels of IFN-γ, IL-4, IL-33 and TSLP using a multiplex bead immunoassay. RESULTS: Inflamed sites in both patients with plaque-induced gingivitis and chronic periodontitis showed statistically significantly higher volume of GCF compared to non-inflamed sites in all patients. IFN-γ could be detected in about 50-70% of the samples analyzed and at significantly higher levels in sites with periodontitis compared to healthy sites in patients with chronic periodontitis (p = 0.035). We also show a statistically significant decrease of IFN-? in healthy sites of patients with chronic periodontitis as compared to gingivitis sites in patients with plaque-induced gingivitis (p = 0.047). Only some of the GCF samples showed detectable levels for IL-4 and TSLP, while IL-33 was below the detection level in all samples collected. CONCLUSIONS: These results suggest that IFN-γ levels in GCF depend on the clinical stage of the site and not on the disease stage of the patient, but need to be expanded to a greater number of subjects and additional analysis of corresponding gingival tissue biopsies for cytokine gene expression.

Insights on the genotype distribution among Cryptococcus neoformans and C. gattii Portuguese clinical isolates.

This study provides a comprehensive picture of the C. neoformans/C. gattii molecular types most often associated with human cryptococcosis in Portugal and assesses the impact of C. gattii in these infections. One hundred and twenty-two clinical isolates, from distinct patients, were identified as C. neoformans and genotyped by URA5-RFLP, with the molecular types VNI (45.5 %) and VNIII (30.9 %) being the most commonly found ones. The molecular types VNII (11.4 %) and VNIV (11.4 %) were less abundant. One patient was found to be infected with a VGII isolate. This patient exhibited unusual clinical symptoms of cryptococcosis, reinforcing the suspicion for the presence of a different genotypic pattern, as determined afterwards. This case was detected in 2007 and is the first report of a potential autochthonous C. gattii infection case in Portugal, as the patient revealed no historical record of travelling outside the country.

Levels of Selenomonas species in generalized aggressive periodontitis.

BACKGROUND AND OBJECTIVE: To compare the levels of Selenomonas sputigena and uncultivated/unrecognized Selenomonas species in subgingival biofilms from periodontally healthy subjects and from subjects with generalized aggressive periodontitis. MATERIAL AND METHODS: Fifteen periodontally healthy subjects and 15 subjects with generalized aggressive periodontitis were recruited and their clinical periodontal parameters were evaluated. Nine subgingival plaque samples were collected from each subject and all were individually analyzed for the levels of 10 bacterial taxa, including cultured and uncultivated/unrecognized microorganisms, using the RNA-oligonucleotide quantification technique. Between-group differences in the levels of the test taxa were determined using the Mann-Whitney U-test. RESULTS: Subjects with generalized aggressive periodontitis showed significantly higher mean counts of Porphyromonas gingivalis, S. sputigena and the Mitsuokella sp. Human Oral Taxon (HOT) 131 (previously described as Selenomonas sp. oral clone CS002), while higher mean counts of Actinomyces gerencseriae and Streptococcus sanguinis were found in periodontally healthy subjects (p < 0.01). Selenomonas sp. HOT 146 was only detected in the generalized aggressive periodontitis group. In the generalized aggressive periodontitis group, the levels of P. gingivalis and S. sputigena were higher in deep sites (probing depth ≥ 5 mm) than in shallow sites (probing depth ≤ 3 mm) (p < 0.01). Furthermore, in subjects with generalized aggressive periodontitis, sites with probing depth of ≤ 3 mm harbored higher levels of these two species than sites with the same probing depth in periodontally healthy subjects. There were positive correlations between probing depth and the levels of P. gingivalis (r = 0.77; p < 0.01), S. sputigena (r = 0.60; p < 0.01) and Selenomonas dianae (previously described as Selenomonas sp. oral clone EW076) (r = 0.42, p < 0.05). CONCLUSION: S. sputigena and Mitsuokella sp. HOT 131 may be associated with the pathogenesis of generalized aggressive periodontitis, and their role in the onset and progression of this infection should be investigated further.

Rediscovering Sig Socransky, the genius and his legacy.

Some individuals make contributions so vital to their field of knowledge that their names become almost synonymous with that field. This is the case of Sig Socransky and the field of periodontal microbiology. Sig Socransky, or simply Sig, was born in Toronto, Canada and received his DDS degree from the University of Toronto in 1957. He studied microbiology and periodontology at Harvard, receiving a certificate in 1961. That same year he was recruited to work as a Research Associate at the Forsyth Dental Center. In 1968, he was nominated Senior Member of the Staff and Head of the Department of Periodontology. During his 50-year career at Forsyth, Sig published over 300 manuscripts, keeping an average of 7 publications per year. His work had an indelible impact in the fields of periodontology and oral microbiology. All these accomplishments pale in comparison with the impact that Sig had on a personal level. We have collected testimonials from some of his former students, closest collaborators, and friends in an attempt to give readers an insight into Sig's personality. We hope we can offer those who knew him through his work a glimpse of how it felt to interact with this remarkable individual.

Comparison of microbial changes in early redeveloping biofilms on natural teeth and dentures.

BACKGROUND: Surfaces and fluids can affect oral bacterial colonization. The aim of this study is to compare redeveloping biofilms on natural teeth and dentures. METHODS: Supragingival plaque samples were taken from 55 dentate individuals and the denture teeth of 62 edentulous individuals before and after professional cleaning. Also, samples from seven "teeth" (samples included dentures) in randomly selected quadrants were collected after 1, 2, 4, and 7 days of no oral hygiene. Samples were analyzed using checkerboard DNA-DNA hybridization. Counts and proportions of 41 bacterial taxa were determined at each time point, and significant differences were determined using the Mann-Whitney U test. Ecological succession was determined using a modified moving window analysis. RESULTS: Mean total DNA probe counts were similar precleaning but were higher in dentate individuals at all post-cleaning visits (P <0.01). Precleaning edentate biofilms had higher counts and proportions of Streptococcus mitis, Streptococcus oralis, and Streptococcus mutans, whereas dentate individuals had higher proportions of Tannerella forsythia, Selenomonas noxia, and Neisseria mucosa. By day 2, mean counts of all taxa were higher in natural teeth, and most remained higher at day 7 (P <0.01). Succession was more rapid and complex in dentate individuals. Both groups demonstrated increased proportions of S. mitis and S. oralis by day 1. N. mucosa, Veillonella parvula, and Eikenella corrodens increased in both groups, but later in samples from edentate individuals. CONCLUSIONS: "Mature" natural and denture teeth biofilms have similar total numbers of bacteria but different species proportions. Post-cleaning biofilm redevelopment is more rapid and more complex on natural teeth than on denture teeth.

Microbiologic profile of endodontic infections from HIV- and HIV+ patients using multiple-displacement amplification and checkerboard DNA-DNA hybridization.

OBJECTIVE: To compare the microbiota of endodontic infections in necrotic pulp from HIV-negative and HIV-positive subjects. MATERIALS AND METHODS: Root canal samples from necrotic pulp were collected from 40 HIV- and 20 HIV+ subjects. Pulps were amplified using multiple displacement amplification (MDA). Then, checkerboard DNA-DNA hybridization was employed to assess the levels of 107 microbial taxa. The percentage of DNA probe count and the percentage of teeth colonized by each test species were investigated. Significant differences between groups regarding proportions of taxa and prevalence of the test species were sought using the Mann-Whitney test and the Chi-square analysis, respectively. RESULTS: The most prevalent taxa detected were Dialister pneumosintes, Stenotrophomonas maltophilia, Streptococcus sobrinus, Corynebacterium diphteriae, and Helicobacter pylori among HIV- subjects and D. pneumosintes, Prevotella tannerae, Porphyromonas gingivalis, Parvimonas micra, Prevotella nigrescens, and Corynebacterium diphtheriae among HIV+ individuals. D. pneumosintes, C. diphtheria, and C. albicans were the most abundant species in the HIV- group, whereas the predominant taxa in HIV+ samples were P. tannerae, D. pneumosintes and Olsenella uli. P. tannerae, O. uli, Veilonella dispar, Bacteroides fragilis, and Actinomyces meyeri were significantly more abundant in HIV+ samples. CONCLUSIONS: There were significant differences in the prevalence and proportions of specific microbial taxa between HIV- and HIV+ individuals. The root canal microbiota may represent a reservoir of important oral and medical pathogens, mainly in HIV+ individuals.