Apical periodontitis, an acute or chronic inflamination around the apex of the tooth, is caused by bacteria in the root canal. In Sweden the dentists devote around 10X of their total time to treating this disease. The treatment usually requires 3 to 5 sessions. The treatment may fail in up to 25X of the cases. In the present study various treatment regimens were evaluated. One hundred and forty singlerooted teeth with apical periodontitis were treated. The importance of mechanical instrumentation, irrigating solutions and antibacterial dressings in eliminating bacteria from the infected root canals was studied using bacteriological techniques. The healing of the apical periodontitis after treatment was followed for 2 to 5 years on recall radiographs. Bacteria were found in all 140 root canals at the beginning of the treatment. Most of these bacteria were anaerobes and they represented a restricted group of bacteria compared to the bacteria present at other sites in the oral cavity. Mechanical instrumentation with files and reamers in combination with saline irrigation reduced the number of bacterial cells in the root canal 100- to 1000-fold during one treatment session. Bacteria could be eliminated from about half the number of root canals if this treatment was performed at 4 sessions. Mechanical instrumentation and irrigation with 0.5X or 5X sodium hypochlorite solutions or with the 5X solution in combination with 15X EDTA solution wa3 more efficient and the bacteria were eliminated from about half the treated canals after one treatment session. The bacteria which persisted in the root canal after this treatment usually increased in number during the interval up to the next session and reached levels which were often as high as in the initial sample at the previous session. All bacteria persistent in the root canals after the previous treatment regimens were with 2 exceptions eliminated by dressing the root canals for 1 to 2 months with calcium hydroxide paste. Thirty-four out of 35 root canals treated at the first session with mechanical instrumentation, irrigation with sodium hypochlorite solution and dressed with calcium hydroxide paste were free of bacteria at the second session. Calcium hydroxide paste was superior to camphorated phenol and camphorated paramonochlorophenol as dressing. Healing of 79 out of the 140 treated teeth was followed for 2 to 5 years. The majority of the lesions healed completely or decreased in size in such a way that they could be expected to heal. There was no or only an insignificant decrease in the size of the lesions in 5 cases. In 2 of these cases bacteria were demonstrated in the periapical tissues and in a third case dentin chips. Periapical lesions may thus fail to heal in a few cases due to an establishment of bacteria outside the root canal, and in that site the bacteria are inaccessible to conventional endodontic treatment. The present study showed that treatment of the majority of infected non-vital teeth can be completed in only 2 sessions, if mechanical instrumentation, sodium hypochlorite irrigation and calcium hydroxide dressing are combined. / <p>Diss. (sammanfattning) Umeå : Umeå universitet, 1986, härtill 5 uppsatser.</p> / digitalisering@umu

Thesis (M.S.)--University of Michigan, Ann Arbor, 1985. / Typescript (photocopy). Includes bibliographical references (leaves 61-67). Also issued in print.

Thesis (M.S.)--University of Michigan, Ann Arbor, 1985. / Typescript (photocopy). eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 61-67).

Microbiological screening of antimicrobial residues in eggs needs special attention because of the high level of naturally occurring inhibitors contained in eggs which often lead to false positive results. However, it was discovered that heating egg samples at 800C for 10 minutes inactivated the inhibitors. The new bacteriological screening test for antimicrobial residues in eggs which was developed during this study, contains viable spores of Geobacillus stearothermophilus which are sensitive to antimicrobial residues including beta-lactams, tetracycline’s and macrolides. The new test method was validated based on the comparison with a reference method, namely the Kundrat micro-screening four-plate test,1 and published literature of another standard reference method, the Premi®Test. A preliminary trial was conducted on 36 hens that were given therapeutic oral doses of overthe- counter antimicrobials daily for seven days with one of eleven antimicrobials based on the manufacturer’s recommendations. Eggs were collected from the hens during and after treatment and tested for the presence or absence of antimicrobial residues. Several performance criteria and minimum detection concentrations were estimated and discussed. Some agreements and differences were found between the new and the reference tests with the new test being more sensitive to beta-lactams, tetracyclines and macrolides than the Kundrat and Premi®Test on the average. The use of florfenicol and norfloxacin in laying hens is banned and therefore there are no maximum residue limits (MRL) or published Premi®Test values. For meat, the MRL is 100mg/kg. It was therefore concluded that the new screening test could be used for routine screening of antimicrobial residues in eggs. A two seasonal survey was also conducted to determine the prevalence of antimicrobial residues in commercial chicken eggs in Tshwane area of Gauteng Province, South Africa. Although the season did not impact statistically on the antibiotic residues found in the eggs; eggs sold at the roadside (informal businesses), certain egg brands, and those sold at lower prices were found to be more likely to contain antibiotic residues than those obtained from formal outlets and at higher prices. Copyright / Dissertation (MSc)--University of Pretoria, 2011. / Production Animal Studies / unrestricted

Bacteria are inarguably the most ubiquitous and adaptive organisms on the planet. The vast, diverse community of microbes residing in soil are mostly studied using sequencing technologies because over 99% of them are currently uncultivable in the laboratory. This lack of diverse bacterial cultivation presents a serious challenge for modern microbiological and medical science where the discovery of novel antibiotic producers and microbial products has been outpaced by the rise in drug resistance. This study designed and tested two new cost-effective culture systems called the “Dynamic Soil Environment” and Soil Extract Systems with the goal of increasing the cultivable communities of diverse bacteria in a soil sample over standard methods. Illumina MiSeq sequencing and DADA2 pipeline protocols were used to analyze community DNA from cultivated samples and source soil metagenomes. Autoclaved soil extract media in the Soil Extract Experiment yielded a statistically significantly greater Shannon’s (p = 0.008) and Simpson’s diversity (p = 0.007) of bacteria over pH modified (6.4) nutrient agar media over 30 days of incubation. Autoclaved soil extract media was also able to cultivate, on average, 33% of species in bulk soil sequences compared to 27% from standard nutrient agar however these differences weren’t statistically significant. The length of incubation had a lesser effect than media type on yield of bacteria over 30 days in batch culture conditions. Species richness and diversity generally decreased over time except in soil extract samples. In the Dynamic Soil Environment experiment, membrane plates placed on a live soil environment produced a slightly higher diversity than autoclaved membrane plates and control plates without soil, however, these differences were not statistically significant except when analyzed with Chao1 diversity (0.041). Cultivated bacterial diversity and communities differed more according to media type than soil environment with statistically significant differences between standard and pH modified nutrient agar. Media with a 5.8 pH buffer produced a significantly higher relative abundance of the well-known antibiotic-producers, Actinobacteria (t(10) = -5.715, p < .000) and also Proteobacteria (t(10) = -10.127, p < .000). This study establishes cost-effective methods of cultivating more diverse bacterial communities for low-funded laboratories. Culture conditions for the reliable cultivation of higher relative abundances of bacterial groups belonging to Actinobacteria and Proteobacteria are also established with the Dynamic Soil Environment Experiment. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2019. / FAU Electronic Theses and Dissertations Collection

Thesis (M.S.)--University of Michigan, 1965.

Thesis equivalent (M.P.H.)--University of Michigan, 1948.

Thesis (M.S.)--University of Michigan, 1960.

Thesis (M.S.)--University of Michigan, 1961.

Thesis (M.S.)--University of Michigan, 1960.