Different sealing materials preventing the microbial leakage into the screw-retained implant restorations: an in vitro analysis by DNA checkerboard hybridization.

OBJECTIVES: The aim of this controlled in vitro study was to identify and quantify up to 38 microbial species penetrating through the screw-retained implant prostheses with different sealing materials. MATERIAL AND METHODS: Sixty morse cone implants were restored with single-unit screw-retained prostheses. All the components were randomly divided into five groups (n = 12) according to the proposed materials: (1) polytetrafluoroethylene tape+composite resin; (2) polytetrafluoroethylene tape+gutta-percha; (3) polytetrafluoroethylene tape+light-polymerized provisional composite; (4) cotton pellet+gutta-percha; and (5) cotton pellet+light-polymerized provisional composite. Human saliva was used as contaminant media, and DNA checkerboard hybridization was used to identify and quantify microbial species. RESULTS: Microbial leakage was observed in all groups: M. salivarium, S. pasteuri, P. nigrescens, and P. melaninogenica were the species presenting the highest values of genome count, prevalence, and proportion within the groups. The total microbial mean counts (×105 , ±SD) were as follows: Group 1 (2.81 ± 0.38), Group 2 (3.41 ± 0.38), Group 3 (6.02 ± 1.48), Group 4 (6.40 ± 1.42), and Group 5 (17.45 ± 1.67). Group 5 showed the higher microbial counts (P < 0.001). CONCLUSIONS: Moderate to high counts of pathogenic/nonpathogenic species were detected in the inner parts of implants from all groups. The lowest values of microbial counts were recorded for polytetrafluoroethylene tape associated with composite resin or gutta-percha; cotton pellet associated with light-polymerized provisional composite presented the highest microbial counts.

Profile of bacteria colonizing the exposed bone of patients with anti-osteoclastic drug-related osteonecrosis of the jaws.

Microbial etiology for anti-osteoclastic drug-related osteonecrosis of the jaw (ARONJ) was suggested. This study investigates any link between bacteria colonizing ARONJ sites and other oral cavity sites. Microbiota samples of 10 ARONJ patients were collected from the exposed bone, adjacent teeth, contralateral teeth, and tongue. DNA checkerboard hybridization was used for microbiota analysis with 43 genomic DNA probes prepared from human oral bacterial (38) and candida (5) species, using Socransky's bacterial complexes as a guide. The frequency and the mean proportion of each bacterial species were used. Eikenella corrodens, Streptococcus constellatus, and Fusobacterium nucleatum were dominant in the ARONJ sites and detected in most teeth samples. Staphylococcus aureus was also dominant in the ARONJ sites and tongue. Significant correlations were found between the mean proportions of bacterial species colonizing adjacent teeth, contralateral teeth, and tongue (p < 0.001, R(2) > 0.69). No significant correlation (p > 0.05, R(2) < 0.025) was found between bacteria colonizing ARONJ sites and other evaluated sites. Within the study limitations, it was concluded that the primary sources of microorganisms colonizing ARONJ sites could be other sites such as teeth and tongue. The microbial profile of the necrotic bone is predominantly colonized with bacteria from Socransky's green and orange complexes, as well as with species associated with bone infections.

Bacterial profile and bone healing in rats receiving cancer therapeutic doses of bisphosphonates and corticosteroids: a pilot study.

The microbial aetiology of bisphosphonate-related osteonecrosis of the jaw (BRONJ) remains undefined. This study investigated the oral microbiota and socket healing after zoledronic acid (ZA) and dexamethasone (DX) administration. Fourteen rats assigned randomly to experimental (n=8) and control (n=6) groups were injected with ZA+DX or saline, respectively, for 3 weeks prior to and 9 weeks after the extraction of left first upper and lower molars. Whole genomic DNA probes of 38 bacterial species and five Candida species were hybridized to DNA extracted from biofilm samples on exposed bone and adjacent teeth. Only experimental rats exhibited exposed bone at euthanasia. All BRONJ-like lesions were colonized by Staphylococcus pasteuri, Streptococcus parasanguinis, and Streptococcus mitis. A significant correlation was observed between the mean proportions of species colonizing BRONJ-like lesions and the teeth of experimental rats (r=0.818, P<0.001). Significant differences were seen in several species colonizing the teeth of control rats compared to experimental rats (P<0.05). Micro-computed tomography analyses revealed higher residual bone in mandibular (P=0.001) and maxillary (P=0.108) tooth sockets of experimental rats. BRONJ-like lesions were colonized mainly by non-pathogenic bacteria. ZA+DX administered to rats at doses equivalent to those given to cancer patients resulted in changes to the oral biofilm and impaired bone healing following tooth extraction.

Microbial diversity of the supra- and subgingival biofilm of healthy individuals after brushing with chlorhexidine- or silver-coated toothbrush bristles.

Nanoparticulate silver has recently been reported as an effective antimicrobial agent. The aim of this clinical study was to investigate the potential changes on the oral microbiota of healthy individuals after controlled brushing with chlorhexidine- or silver-coated toothbrush bristles. Twenty-four healthy participants were enrolled in this investigation and randomly submitted to 3 interventions. All the participants received, in a crossover format, the following toothbrushing interventions: (i) chlorhexidine-coated bristles, (ii) silver-coated bristles, and (iii) conventional toothbrush (Control). All the interventions had a duration of 30 days. The DNA checkerboard hybridization method was used to identify and quantify up to 43 microbial species colonizing the supra- and subgingival biofilm. The supragingival samples presented higher genome counts than the subgingival samples (p < 0.0001). The total genome counts from the Control group showed the highest values, followed by the silver and chlorhexidine groups (p < 0.0001). After 4 weeks of brushing, the silver-coated and chlorhexidine-coated bristles were capable of reducing or maintaining lower levels of the bacterial counts of the putative periodontal pathogens Tanerella forsythia, Treponema denticola, and Porphyromonas gingivalis. Other major periodontal pathogens, such as Prevotella intermedia, Fusobacterium nucleatum, Prevotella nigrescens, and Parvimonas micra, were also detected at lower levels. The toothbrush bristles impregnated with silver nanoparticles reduced the total and individual genome count in the supra- and subgingival biofilm after 4 weeks of brushing. Chlorhexidine was not effective in reducing the total genome counts in both supra- or subgingival biofilm after 4 weeks of brushing. Chlorhexidine reduced the individual genome counts in the supragingival biofilm for most of the target species, including putative periodontal pathogens.

Uso de la técnica de hibridización checkerboard ADN-ADN para la identificación de la microbiota periimplantaria: revisión bibliográfica / Use of checkerboard DNA-DNA hybridization technique for periimplantitis microbiota identification: literature review

El término Periimplantitis hace referencia a la condición de enfermedad en los tejidos de soporte de los implantes bucales. Su etiología es multifactorial, aunque la biopelícula microbiana desempeña un papel esencial en la etiopatogenia de la enfermedad. A través de técnicas de cultivo, se han identificado algunas bacterias implicadas en la etiopatogenia de las periodontopatías, entre estas, especies pertenecientes a los Géneros Fusobacterium, Prevotella y Porphyromonas. El desarrollo de técnicas de biologia molecular permite la identificación de especies bacterianas que antes no eran referidas como parte de la microbiota responsable de la patogénesis periodontal. La detección de la microbiota presente en los sacos periodontales que se originan alrededor de los implantes es necesaria para el establecimiento de la conducta terapéutica a ser instruida, más aún si se toma den consideración que las alteraciones de las estructuras de soporte están directamente relacionadas con muchos de los microorganismos presentes y constituyen una de las causas más frecuentes de fracaso del tratamiento rehabilitador con implantes. El objetivo de este artículo es presentar una revisión bibliográfica de la técnica de hibridización checkerboard ADN-ADN para la identificación de los microorganismos más frecuentemente asociados a la peri-implantitis

The periimplantitis term is characterized as a disease that affects the support implant tissues. It has a multifactorial etiology, with an important role of the biofilm on the periodontal diseases. The culture techniques use possibilited to identify bacterias responsible for periodontal alterations, as Fusobacterium, Prevotella and Porphyromonas ssp. The development of the molecular biology techniques possibilited the identification of some bacterial species, that there were not related in the literature and there were responsible for periodontal pathogenesis. The microbiota present on the periodontal pockets in overdentures may contribute in the orientation of the therapeutic procedures, considering that the structural alterations on the periodontal tissues are straightly related to microorganism presence, and it constitutes one of the causes that affect the oral rehabilitation treatment with implants. This, the aim of this study was to present a literature review of DNA-DNA hybridization technique in the identification of the microorganisms more related to periimplantitis

DNA Checkerboard Method for Bacterial Pathogen Identification in Oral Diseases / Método de Chequeo de DNA para la Identificación de Bacterias Patógenas en las Enfermedades de la Cavidad Oral

This work aim to show by literature review the principal characteristics of the DNA checkerboard method for bacterial pathogens identification in oral diseases, showing the most varieties uses and applications of this technique.

Este trabajo tiene como objetivo, presentar en una revisión de la literatura, las principales características del método de chequeo del DNA para la identificación de bacterias patógenas en la cavidad oral, mostrando las diferentes utilizaciones y aplicaciones de esta técnica.