Avaliação comparativa da remodelação óssea periimplantar em implantes com junção cone-morse e hexágono externo: estudo clínico randomizado controlado, duplo cego, boca dividida

Background: Several theories, such as the biological width formation, the inflammatory reactions due to the implant-abutment microgap contamination, and the periimplant stress/strain concentration causing bone microdamage accumulation, have been suggested to explain early periimplant bone loss. However, it is yet not well understood to which extent the implant-abutment connection type may influence the remodeling process around dental implants. Aim: to evaluate clinical, bacteriological, and biomechanical parameters related to periimplant bone loss at the crestal region, comparing external hexagon (EH) and Morse-taper (MT) connections. Materials and methods: Twelve patients with totally edentulous mandibles received four custom made Ø 3.8 x 13 mm implants in the interforaminal region of the mandible, with the same design, but different prosthetic connections (two of them EH or MT, randomly placed based on a split-mouth design), and a immediate implant- supported prosthesis. Clinical parameters (periimplant probing pocket depth, modified gingival index and mucosal thickness) were evaluated at 6 sites around the implants, at a 12 month follow-up. The distance from the top of the implant to the first bone-to-implant contact – IT-FBIC was evaluated on standardized digital peri-apical radiographs acquired at 1, 3, 6 and 12 months follow-up. Samples of the subgingival microbiota were collected 1, 3 and 6 months after implant loading. DNA were extracted and used for the quantification of Tanerella forsythia, Porphyromonas gingivalis, Aggragatibacter actinomycetemcomitans, Prevotella intermedia and Fusobacterium nucleatum. Comparison among multiple periods of observation were performed using repeated-measures Analysis of Variance (ANOVA), followed by a Tukey post-hoc test, while two-period based comparisons were made using paired t- test. Further, 36 computer-tomographic based finite element (FE) models were accomplished, simulating each patient in 3 loading conditions. The results for the peak EQV strain in periimplant bone were interpreted by means of a general linear model (ANOVA). Results: The variation in periimplant bone loss assessed by means of radiographs was significantly different between the connection types (P<0.001). Mean IT-FBIC was 1.17±0.44 mm for EH, and 0.17±0.54 mm for MT, considering all evaluated time periods. All clinical parameters presented not significant differences. No significant microbiological differences could be observed between both connection types. Most of the collected samples had very few pathogens, meaning that these regions were healthy from a microbiological point of view. In FE analysis, a significantly higher peak of EQV strain (P=0.005) was found for EH (mean 3438.65 µ∑) compared to MT (mean 840.98 µ∑) connection. Conclusions: Varying implant-abutment connection type will result in diverse periimplant bone remodeling, regardless of clinical and microbiological conditions. This fact is more likely attributed to the singular loading transmission through different implant-abutment connections to the periimplant bone. The present findings suggest that Morse-taper connection is more efficient to prevent periimplant bone loss, compared to an external hexagon connection.

Microbiota in the oral subgingival biofilm is associated with obesity in adolescence

To test the hypothesis whether microbiota in oral biofilm is linked with obesity in adolescents we designed this cross-sectional study. Obese adolescents (n = 29) with a mean age of 14.7 years and normal weight subjects (n = 58) matched by age and gender were examined with respect to visible plaque index (VPI%) and gingival inflammation (bleeding on probing (BOP%)). Stimulated saliva was collected. They answered a questionnaire concerning medical history, medication, oral hygiene habits, smoking habits, and sociodemographic background. Microbiological samples taken from the gingival crevice was analyzed by checkerboard DNA-DNA hybridization technique. The sum of bacterial cells in subgingival biofilm was significantly associated with obesity (P < 0.001). The link between sum of bacterial cells and obesity was not confounded by any of the studied variables (chronic disease, medication, VPI%, BOP%, flow rate of whole saliva, or meal frequency). Totally 23 bacterial species were present in approximately threefold higher amounts, on average, in obese subjects compared with normal weight controls. Of the Proteobacteria phylum, Campylobacter rectus and Neisseria mucosa were present in sixfold higher amounts among obese subjects. The association between obesity and sum of bacterial cells in oral subgingival biofilm indicates a possible link between oral microbiota and obesity in adolescents.

Microbiota saprófita associada à doença periodontal em cães

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Microbiota bucal de pacientes HIV positivos: relação com o uso de drogas antirretrovirais e condições de saúde

Pós-graduação em Odontologia - FOA

Família Enterobacteriaceae, Acinetobacter baumannii e Pseudomonados na microbiota bucal de pacientes mantidos em unidades de terapia intensiva

Enteric organisms, pseudomonads and other opportunistic microorganisms in the oral microbiota have been linked to serious infections in patients hospitalized in intensive care units (ICU). The present study evaluated the presence of family Enterobacteriaceae, Pseudomonas aeruginosa, and Acinetobacter baumannii in the mouth of patients in ICU, correlating it with oral and systemic conditions. Data on health, socioeconomic status, medication use, drug addiction, medical and family histories of patients held for more than 72 hours in the ICU with a diagnosis of severe infection or that developed this condition after entry in said unit were obtained. Fifty patients provided clinical samples of supragingival and subgingival biofilms, saliva and oral mucous membranes were collected, as well as respiratory secretions from patients with pneumonia, blood and urine for sepsis. The presence of target microorganisms was carried out by polymerase chain reaction (PCR) and by culture using selective media. The Chi-square and Mann-Whitney tests were used for statistical analysis, and the significance level was 5%. The intraoral clinical conditions of the patients were poor. The family Enterobacteriaceae was the most prevalent, affecting 39.5% of the supragingival biofilm samples of patients attended in ICU and 18.6% of patients in the control group, besides the rods were the only group found in extraoral samples.

Caratterizzazione microbiologica ed epidemiologica del microbiota del cavo orale mediante metodiche colturali e molecolari

La ricerca si è focalizzata su due degli aspetti di interesse odontoiatrico più diffusi: la carie dentaria e la parodontite cronica. Il problema della carie dentaria è stato studiato in una popolazione di 39 soggetti affetti da cardiopatia congenita in cui la scarsa igiene orale è fattore di rischio per problematiche di salute generale e soprattutto per lo sviluppo di endocardite infettiva. I dati osservati e confrontati con quelli di un omogeneo gruppo di controllo dimostrano che nella dentatura decidua questi bambini hanno più denti cariati, come dimostrato dalla significativa differenza dell'indice dmft. Nella dentatura permanente non si osservano differenze tra i due gruppi. La carica microbica totale rilevata nella saliva e la presenza di Streptococcus mutans non mostrano differenze tra i due gruppi. I problemi di parodontite cronica sono stati studiati in un gruppo di 352 soggetti italiani adulti in cui si è definita la prevalenza dei 6 più importanti patogeni parodontali e la possibile correlazione con parametri clinici (pus, sanguinamento al sondaggio - BOP, profondità di sondaggio della tasca parodontale – PPD). Tra le 6 specie batteriche ricercate, quello di più frequente riscontro è stato Fusobacterium nucleatum (95%), mentre quello con carica batterica più alta è stato Tannerella forsythia. La carica batterica di Porphyromonas gingivalis, Treponema denticola, Tannerella forsythia e Fusobacterium nucleatum ha mostrato una correlazione diretta con il BOP e la presenza di pus. Inoltre, si è riscontrato che la carica batterica di tutte le specie (tranne Aggregatibacterium actinomycetemcomitans) aumenta all'aumentare del PPD. Tra le variabili studiate, PPD rappresenta il più importante fattore di rischio per la presenza di parodontopatogeni, mentre BOP è un indicatore di rischio per la ricerca del complesso rosso.

Oral microbiota in Swiss adolescents

OBJECTIVES: The purpose of the study was to determine the prevalence of different oral microbes in gingival plaque samples and in samples from the dorsum of the tongue in a Swiss adolescent population. MATERIALS AND METHODS: Ninety-nine adolescents between 15 and 18 years were enrolled. Plaque index, bleeding on probing (BOP), the periodontal screening index, and decayed missed filled tooth (DMFT) index were recorded. Samples from subgingival plaque and swabs from the tongue were analyzed by the Checkerboard DNA-DNA hybridization method. Additionally, counts of Streptococus mutans and Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Tannerella forsythia, and Treponema denticola were determined by real-time PCR. RESULTS: Periodontitis was not diagnosed in any of the subjects but all of them presented signs of gingival inflammation displaying a mean BOP of 28%. Ten (10.1%) subjects were tested positive for P. gingivalis, each 22 (22.2%) for A. actinomycetemcomitans and T. forsythia, (47.5%) for T. denticola. T. denticola and S. mutans showed a high affinity to the gingival plaque, whereas T. forsythia was often detected from the dorsum of the tongue. DMFT was associated with S. mutans counts, and BOP correlated with counts of P. gingivalis and T. denticola. CONCLUSIONS: The present data indicate that: (a) gingivitis but not periodontitis is a common finding among Swiss adolescents, and (b) bacteria associated with periodontitis were frequently detected in the subgingival dental plaque and on the dorsum of the tongue in Swiss adolescents with gingivitis. CLINICAL RELEVANCE: Although gingivitis was a frequent finding in Swiss adolescents, periodontitis was not detected in this population. The dorsum of the tongue appears to represent an important reservoir for periodontopathic bacteria.

Dietary flavonoids from modified apple reduce inflammation markers and modulate gut microbiota in mice

Apples are rich in polyphenols, which provide antioxidant properties, mediation of cellular processes such as inflammation, and modulation of gut microbiota. In this study we compared genetically engineered apples with increased flavonoids [myeloblastis transcription factor 10 (MYB10)] with nontransformed apples from the same genotype, "Royal Gala" (RG), and a control diet with no apple. Compared with the RG diet, the MYB10 diet contained elevated concentrations of the flavonoid subclasses anthocyanins, flavanol monomers (epicatechin) and oligomers (procyanidin B2), and flavonols (quercetin glycosides), but other plant secondary metabolites were largely unaltered. We used these apples to investigate the effects of dietary flavonoids on inflammation and gut microbiota in 2 mouse feeding trials. In trial 1, male mice were fed a control diet or diets supplemented with 20% MYB10 apple flesh and peel (MYB-FP) or RG apple flesh and peel (RG-FP) for 7 d. In trial 2, male mice were fed MYB-FP or RG-FP diets or diets supplemented with 20% MYB10 apple flesh or RG apple flesh for 7 or 21 d. In trial 1, the transcription levels of inflammation-linked genes in mice showed decreases of >2-fold for interleukin-2 receptor (Il2rb), chemokine receptor 2 (Ccr2), chemokine ligand 10 (Cxcl10), and chemokine receptor 10 (Ccr10) at 7 d for the MYB-FP diet compared with the RG-FP diet (P <0.05). In trial 2, the inflammation marker prostaglandin E2 (PGE2) in the plasma of mice fed the MYB-FP diet at 21 d was reduced by 10-fold (P < 0.01) compared with the RG-FP diet. In colonic microbiota, the number of total bacteria for mice fed the MYB-FP diet was 6% higher than for mice fed the control diet at 21 d (P = 0.01). In summary, high-flavonoid apple was associated with decreases in some inflammation markers and changes in gut microbiota when fed to healthy mice.

Comparison of stool microbiota compositions, stool alpha1-antitrypsin and calprotectin concentrations, and diarrhoeal morbidity of Indonesian infants fed breast milk or probiotic/prebiotic-supplemented formula

Aim The composition of faecal microbiota of babies is known to be influenced by diet. Faecal calprotectin and α1-antitrypsin concentrations may be associated with mucosal permeability and inflammation. We aimed to assess whether there was any difference after consumption of a probiotic/prebiotic formula on faecal microbiota composition, calprotectin and α1-antitrypsin levels, and diarrhoea in comparison with breast milk-fed Indonesian infants. Methods One hundred sixty infants, 2 to 6 weeks old, were recruited to the study. They were either breastfed or formula fed (80 per group). Faecal samples were collected at recruitment and 3 months later. Bacterial groups characteristic of the human faecal microbiota were quantified in faeces by quantitative polymerase chain reaction. Calprotectin and α1-antitrypsin concentrations were measured using commercial kits. Details of diarrhoeal morbidity were documented and rated for severity. Results The compositions of the faecal microbiota of formula-fed compared with breast milk-fed children were similar except that the probiotic strain Bifidobacterium animalis subsp. lactisâ€...DR10 was more abundant after 3 months consumption of the formula. Alpha1-antitrypsin levels were higher in breastfed compared with formula-fed infants. The occurrence of diarrhoea did not differ between the groups of babies. Conclusion Feeding Indonesian babies with a probiotic/prebiotic formula did not produce marked differences in the composition of the faecal microbiota in comparison with breast milk. Detrimental effects of formula feeding on biomarkers of mucosal health were not observed.

Real-Time PCR : A Molecular Approach to Investigate the Role of Intestinal Microbiota in the Pathophysiology of Irritable Bowel Syndrome

Irritable bowel syndrome (IBS) is a common multifactorial functional intestinal disorder, the pathogenesis of which is not completely understood. Increasing scientific evidence suggests that microbes are involved in the onset and maintenance of IBS symptoms. The microbiota of the human gastrointestinal (GI) tract constitutes a massive and complex ecosystem consisting mainly of obligate anaerobic microorganisms making the use of culture-based methods demanding and prone to misinterpretation. To overcome these drawbacks, an extensive panel of species- and group-specific assays for an accurate quantification of bacteria from fecal samples with real-time PCR was developed, optimized, and validated. As a result, the target bacteria were detectable at a minimum concentration range of approximately 10 000 bacterial genomes per gram of fecal sample, which corresponds to the sensitivity to detect 0.000001% subpopulations of the total fecal microbiota. The real-time PCR panel covering both commensal and pathogenic microorganisms was assessed to compare the intestinal microbiota of patients suffering from IBS with a healthy control group devoid of GI symptoms. Both the IBS and control groups showed considerable individual variation in gut microbiota composition. Sorting of the IBS patients according to the symptom subtypes (diarrhea, constipation, and alternating predominant type) revealed that lower amounts of Lactobacillus spp. were present in the samples of diarrhea predominant IBS patients, whereas constipation predominant IBS patients carried increased amounts of Veillonella spp. In the screening of intestinal pathogens, 17% of IBS samples tested positive for Staphylococcus aureus, whereas no positive cases were discovered among healthy controls. Furthermore, the methodology was applied to monitor the effects of a multispecies probiotic supplementation on GI microbiota of IBS sufferers. In the placebo-controlled double-blind probiotic intervention trial of IBS patients, each supplemented probiotic strain was detected in fecal samples. Intestinal microbiota remained stable during the trial, except for Bifidobacterium spp., which increased in the placebo group and decreased in the probiotic group. The combination of assays developed and applied in this thesis has an overall coverage of 300-400 known bacterial species, along with the number of yet unknown phylotypes. Hence, it provides good means for studying the intestinal microbiota, irrespective of the intestinal condition and health status. In particular, it allows screening and identification of microbes putatively associated with IBS. The alterations in the gut microbiota discovered here support the hypothesis that microbes are likely to contribute to the pathophysiology of IBS. The central question is whether the microbiota changes described represent the cause for, rather than the effect of, disturbed gut physiology. Therefore, more studies are needed to determine the role and importance of individual microbial species or groups in IBS. In addition, it is essential that the microbial alterations observed in this study will be confirmed using a larger set of IBS samples of different subtypes, preferably from various geographical locations.

Lower Gastrointestinal Microbiota in Health and Irritable Bowel Syndrome : Characterisation and Effect of Probiotic Intervention

The human gastrointestinal (GI) microbiota is a complex ecosystem that lives in symbiosis with its host. The growing awareness of the importance of the microbiota to the host as well as the development of culture-free laboratory techniques and computational methods has enormously expanded our knowledge of this microbial community. Irritable bowel syndrome (IBS) is a common functional bowel disorder affecting up to a fifth of the Western population. To date, IBS diagnosis has been based on GI symptoms and the exclusion of organic diseases. The GI microbiota has been found to be altered in this syndrome and probiotics can alleviate the symptoms, although clear links between the symptoms and the microbiota have not been demonstrated. The aim of the present work was to characterise IBS related alterations in the intestinal microbiota, their relation to IBS symptoms and their responsiveness to probiotic theraphy. In this thesis research, the healthy human microbiota was characterised by cloning and sequencing 16S rRNA genes from a faecal microbial community DNA pool that was first profiled and fractionated according to its guanine and cytosine content (%G+C). The most noticeable finding was that the high G+C Gram-positive bacteria (the phylum Actinobacteria) were more abundant compared to a corresponding library constructed from the unfractionated DNA pool sample. Previous molecular analyses of the gut microbiota have also shown comparatively low amounts of high G+C bacteria. Furthermore, the %G+C profiling approach was applied to a sample constructed of faecal DNA from diarrhea-predominant IBS (IBS-D) subjects. The phylogenetic microbial community comparison performed for healthy and IBS-D sequence libraries revealed that the IBS-D sample was rich in representatives of the phyla Firmicutes and Proteobacteria whereas Actinobacteria and Bacteroidetes were abundant in the healthy subjects. The family Lachnospiraceae within the Firmicutes was especially prevalent in the IBS-D sample. Moreover, associations of the GI microbiota with intestinal symptoms and the quality of life (QOL) were investigated, as well as the effect of probiotics on these factors. The microbial targets that were analysed with the quantitative real-time polymerase chain reaction (qPCR) in this study were phylotypes (species definition according to 16S rRNA gene sequence similarity) previously associated with either health or IBS. With a set of samples, the presence or abundance of a phylotype that had 94% 16S rRNA gene sequence similarity to Ruminococcus torques (R. torques 94%) was shown to be associated with the severity of IBS symptoms. The qPCR analyses for selected phylotypes were also applied to samples from a six-month probiotic intervention with a mixture of Lactobacillus rhamnosus GG, L. rhamnosus Lc705, Propionibacterium freudenreichii ssp. shermanii JS and Bifidobacterium breve Bb99. The intervention had been previously reported to alleviate IBS symptoms, but no associations with the analysed microbiota representatives were shown. However, with the phylotype-specific assays applied here, the abundance of the R. torques 94% -phylotype was shown to be lowered in the probiotic-receiving group during the probiotic supplementation, whereas a Clostridium thermosuccinogenes 85% phylotype, previously associated with a healthy microbiota, was found to be increased compared to the placebo group. To conclude, with the combination of methods applied, higher abundance of Actinobacteria was detected in the healthy gut than found in previous studies, and significant phylum-level microbiota alterations could be shown in IBS-D. Thus, the results of this study provide a detailed overview of the human GI microbiota in healthy subjects and in subjects with IBS. Furthermore, the IBS symptoms were linked to a particular clostridial phylotype, and probiotic supplementation was demonstrated to alter the GI microbiota towards a healthier state with regard to this and an additional bacterial phylotype. For the first time, distinct phylotype-level alterations in the microbiota were linked to IBS symptoms and shown to respond to probiotic therapy.