Ashraf F. Fouad

PCR-Based Identification of Bacteria Associated with Endodontic Infections

ABSTRACT PCR primers that target the bacterial 16S rRNA genes (or the tuf gene for the genus Enterococcus) were used to identify 10 putative bacterial pathogens in root canals with necrotic pulp. In addition, the associations of these microorganisms with symptoms and a history of diabetes mellitus were investigated. Microbial samples from the root canals of 24 teeth with necrotic pulp were included in the study. PCR with universal bacterial primers identified bacterial DNA in 22 specimens; the remaining 2 specimens were from intact teeth that had been traumatized 6 months prior to treatment. PCR with specific primers showed that preoperative symptoms were significantly associated with the presence of Streptococcus spp. (P < 0.001 by chi-square analysis). There was also a nonsignificant trend for symptoms to be associated with Fusobacterium nucleatum and Porphyromonas gingivalis (odds ratio, >2) and for diabetes mellitus to be associated with P. gingivalis and Porphyromonas endodontalis (odds ratio, >2). Cloning and sequencing of the universal PCR product in one specimen revealed the presence of an organism related to the genus Olsenella, which has not previously been described in endodontic infections.

Endodontic Interappointment Flare-Ups: A Prospective Study of Incidence and Related Factors

Severe pain and/or swelling following a root canal treatment appointment are serious sequelae. Information varies or is incomplete as to the incidence of these conditions and related factors. In this study, data were collected at root canal treatment appointments on demographics, pulp/periapical diagnoses, presenting symptoms, treatment procedures, and number of appointments. Patients that then experienced a flare-up (a severe problem requiring an unscheduled visit and treatment) had the correlating factors examined. Statistical determinations were by chi-square analysis with significance at 0.05 or less. Nine hundred forty-six visits resulted in an incidence of 3.17% flare-ups. Flare-ups were positively correlated with more severe presenting symptoms, pulp necrosis with painful apical pathosis, and patients on analgesics. Fewer flare-ups occurred in undergraduate patients and following obturation procedures. There was no correlation between patient demographics or systemic conditions, number of appointments, treatment procedures, or taking antibiotics.

Pyrosequencing as a tool for better understanding of human microbiomes.

Abstract Next-generation sequencing technologies have revolutionized the analysis of microbial communities in diverse environments, including the human body. This article reviews several aspects of one of these technologies, the pyrosequencing technique, including its principles, applications, and significant contribution to the study of the human microbiome, with especial emphasis on the oral microbiome. The results brought about by pyrosequencing studies have significantly contributed to refining and augmenting the knowledge of the community membership and structure in and on the human body in healthy and diseased conditions. Because most oral infectious diseases are currently regarded as biofilm-related polymicrobial infections, high-throughput sequencing technologies have the potential to disclose specific patterns related to health or disease. Further advances in technology hold the perspective to have important implications in terms of accurate diagnosis and more effective preventive and therapeutic measures for common oral diseases.

Accuracy of the endex with variations in canal irrigants and formane size

Several electronic apex locators (EALs) are currently available. The manufacturer of a new device, the Endex, claims that it is accurate regardless of canal conditions. This study compared the accuracy of the Endex with that of the Exact-a-pex, the Sono-Explorer Mark III, and the Neosono-D SE as to the effects of fluids in the canal and variation in foramen size. Sixty extracted single-canaled teeth were divided into two groups (narrow and wide foramina), depending on whether the apical foramina permitted the tip of a #30 K file to pass through. An in vitro model was used, in which teeth were fitted in test tubes with the roots immersed in 1% agar in phosphate-buffered saline. Root canal lengths were measured in dry canals, then with ethanol, Xylocaine, and sodium hypochlorite in the canals by each electronic apex locator. These lengths were compared with those of the actual root canal lengths. No significant differences were noted among the instruments in dry canals regardless of the foramen size. The endex was generally superior to the other instruments examined in canals containing conductive fluids, especially where the apical foramen was widened.

Microbial transformation from normal oral microbiota to acute endodontic infections

BackgroundEndodontic infections are a leading cause of oro-facial pain and tooth loss in western countries, and may lead to severe life-threatening infections. These infections are polymicrobial with high bacterial diversity. Understanding the spatial transition of microbiota from normal oral cavities through the infected root canal to the acute periapical abscess can improve our knowledge of the pathogenesis of endodontic infections and lead to more effective treatment. We obtained samples from the oral cavity, infected root canal and periapical abscess of 8 patients (5 with localized and 3 with systemic infections). Microbial populations in these samples were analyzed using next-generation sequencing of 16S rRNA amplicons. Bioinformatics tools and statistical tests with rigorous criteria were used to elucidate the spatial transition of the microbiota from normal to diseased sites.ResultsOn average, 10,000 partial 16S rRNA gene sequences were obtained from each sample. All sequences fell into 11 different bacterial phyla. The microbial diversity in root canal and abscess samples was significantly lower than in the oral samples. Streptococcus was the most abundant genus in oral cavities while Prevotella and Fusobacterium were most abundant in diseased samples. The microbiota community structures of root canal and abscess samples were, however, more similar to each other than to the oral cavity microbiota. Using rigorous criteria and novel bioinformatics tools, we found that Granulicatella adiacens, Eubacterium yurii, Prevotella melaninogenica, Prevotella salivae, Streptococcus mitis, and Atopobium rimae were over-represented in diseased samples.ConclusionsWe used a novel approach and high-throughput methodologies to characterize the microbiota associated normal and diseased oral sites in the same individuals.

Penicillin as a supplement in resolving the localized acute apical abscess

PROBLEM Antibiotics are often prescribed indiscriminately to treat endodontic emergencies. OBJECTIVES This study examined (1) the effect of penicillin supplementation on reduction of symptoms and (2) the course of recovery of localized acute apical abscess after emergency treatment. STUDY DESIGN Patients with pulp necrosis and periapical pain and/or localized swelling were considered. Those eligible did not have any signs of spreading infections. Patients received appropriate local treatment, and a double-blind protocol was used to randomly assign them to one of three groups: penicillin VK group, placebo group, or neither medication group. All received ibuprofen 600 mg four times daily for 24 hours. Patients entered their pre- and postoperative pain and swelling experience on a visual analog scale for up to 72 hours. RESULTS Resolution was fairly rapid in most patients. Statistical analysis of the scores of 32 respondents revealed no significant differences (at p < 0.05) between the three groups in course of recovery or symptoms at any time period. CONCLUSIONS Patients with localized periapical pain or swelling generally recovered quickly with local treatment. The data did not show a demonstrable benefit from penicillin supplementation.

Can Apical Periodontitis Modify Systemic Levels of Inflammatory Markers? A Systematic Review and Meta-analysis

INTRODUCTION This systematic review and meta-analysis investigated evidence to support whether apical periodontitis (AP) can modify the systemic levels of inflammatory markers (IM) in humans. METHODS The MEDLINE, Embase, Cochrane, and PubMed databases were searched between 1948 and 2012, with no language restriction. Additionally, the bibliography of all relevant articles and textbooks were manually searched. Based on inclusion and exclusion criteria, 2 reviewers independently rated the quality of each study based on the Newcastle-Ottawa Scale. The primary outcome variable for meta-analysis was determined by the serum levels of IMs in AP subjects versus healthy controls or in AP subjects before versus after treatment intervention. RESULTS Among the 531 initially identified articles, 20 comprised the final analysis. Thirty-one different IMs were analyzed, with immunoglobulin (Ig) A, IgM, IgG, and C-reactive protein (CRP) being the most commonly investigated. CRP, interleukin (IL)-1, IL-2, IL-6, asymmetrical dimethylarginine, IgA, IgG, and IgM were shown to be increased in patients with AP compared with controls in most studies. Meta-analyses showed that serum levels of IgA (P = .001), IgG (P = .04), and IgM (P < .00001) were increased in humans with AP compared with healthy controls and serum levels of CRP, IgA, IgE, IgG, and IgM were not significantly different between patients with AP before and after treatment (P > .05). CONCLUSIONS Available evidence is limited but consistent, suggesting that AP is associated with increased levels of CRP, IL-1, IL-2, IL-6, asymmetrical dimethylarginine, IgA, IgG, and IgM in humans. These findings suggest that AP may contribute to a systemic immune response not confined to the localized lesion, potentially leading to increased systemic inflammation.

Effect of using electronic apex locators on selected endodontic treatment parameters.

The purpose of this study was to determine the effect of using electronic apex locators on the number of radiographs taken and the adequacy in length of the final obturation. Patients in an undergraduate student endodontics clinic participated in the study. The working length (WL) was estimated by the authors for all cases (36 teeth; 58 canals), using both a preoperative standardized radiograph and an electronic measurement. The students were then asked to place WL files to one of the estimates (electronic or radiographic; chosen by random assignment) and take a WL radiograph. Neither the students nor their instructors knew which method was chosen for the estimates. Once treatment was completed, the total number of working radiographs was counted. The number of cases with acceptable (0 to 2 mm short of the apex) or unacceptable obturation was also blindly registered. An electronic estimate of the WL improved length quality of the final obturation, compared with a radiographic estimate. The number of working radiographs taken was less in the electronic apex locator group in anterior and premolar teeth, but not in molars.

The Effect of Age on Bacterial Penetration of Radicular Dentin

The aim of this study was to determine the effects of patients age on the prevalence and depth of bacterial penetration inside dentinal tubules. Fifty-six single-rooted teeth were divided in two groups based on the patients age: young (ages 18-25) and old (age >or=60). Teeth were instrumented and inoculated with a standardized bacterial load and incubated for 20 days. Histological analysis was performed to determine the degree of infection of the dentinal tubules by counting the number of invaded tubules and the depth of penetration of bacteria inside the tubules. A significantly higher number of tubules were invaded by bacteria in the young group compared with the old group (p = 0.014). Also, the depth of invasion by bacteria was significantly higher in the young than in the old group (p = 0.033). These results suggest that bacterial infection of dentinal tubules occur to a lesser extent in older patients.

Effect of salivary pellicle on antibacterial activity of novel antibacterial dental adhesives using a dental plaque microcosm biofilm model

OBJECTIVES Antibacterial primer and adhesive are promising to inhibit biofilms and caries. Since restorations in vivo are exposed to saliva, one concern is the attenuation of antibacterial activity due to salivary pellicles. The objective of this study was to investigate the effects of salivary pellicles on bonding agents containing a new monomer dimethylaminododecyl methacrylate (DMADDM) or nanoparticles of silver (NAg) against biofilms for the first time. METHODS DMADDM and NAg were synthesized and incorporated into Scotchbond Multi-Purpose adhesive and primer. Specimens were either coated or not coated with salivary pellicles. A microcosm biofilm model was used with mixed saliva from ten donors. Two types of culture medium were used: an artificial saliva medium (McBain), and Brain Heart Infusion (BHI) medium without salivary proteins. Metabolic activity, colony-forming units (CFU), and lactic acid production of plaque microcosm biofilms were measured (n=6). RESULTS Bonding agents containing DMADDM and NAg greatly inhibited biofilm activities, even with salivary pellicles. When using BHI, the pre-coating of salivary pellicles on resin surfaces significantly decreased the antibacterial effect (p<0.05). When using artificial saliva medium, pre-coating of salivary pellicles on resin did not decrease the antibacterial effect. These results suggest that artificial saliva yielded medium-derived pellicles on resin surfaces, which provided attenuating effects on biofilms similar to salivary pellicles. Compared with the commercial control, the DMADDM-containing bonding agent reduced biofilm CFU by about two orders of magnitude. SIGNIFICANCE Novel DMADDM- and NAg-containing bonding agents substantially reduced biofilm growth even with salivary pellicle coating on surfaces, indicating a promising usage in saliva-rich environment. DMADDM and NAg may be useful in a wide range of primers, adhesives and other restoratives to achieve antibacterial and anti-caries capabilities.