Doctor of Philosophy / Dental caries continues to be a significant public health problem affecting mankind in many parts of the world. Microbial activities include the progressive localised destruction of teeth that without treatment, would eventually result in infection of the dental pulp and surrounding periapical tissues. Although the bacteria responsible for caries initiation and early caries progression have been extensively studied, the microbiology of dentine caries is reported to show considerable diversity and has not yet been fully identified. Few studies have analysed the microbiology of deep caries or examined the relationship between the microflora and the histopathy of chronic pulpits in symptomatic teeth. Matched carious dentine samples and dental pulps were obtained from teeth without evidence of periodontal disease but with coronal caries and symptoms of pulpits. Bacteria were cultured from the carious dentine samples under both anaerobic and microaerophilic conditions. Real-time polymerase chain reaction (PCR) technology was also used to identify and enumerate the bacteria. Development of the techniques for the efficient extraction of bacterial DNA from both Gram-negative and Gram-positive bacteria found in carious dentine was an essential prerequisite for molecular analysis. In addition, the dental pulps were processed and categorised into one of four groups on the basis of dominant pathology of the tissue (minimal inflammation, soft tissue degeneration, hard tissue degeneration, inflammatory degeneration). Analysis of the culture data indicated a predominance of Gram-positive bacteria, particularly lactobacilli, while Gram-negative bacteria were also present in significant numbers with Prevotella species the most numerous anaerobic group cultured. Real-time PCR indicated a greater anaerobic microbial load than that determined by colony counting. The total number of anaerobes detected by PCR was 41-fold greater, while Prevotella spp. and Fusobacterium ssp. were 82-fold and 2.4-fold greater respectively. PCR also identified the presence of Micromonas micros, Porphyromonas endodontalis and Porphyromonas gingivalis in 71%, 60% and 52% of carious dentine samples, respectively. Correlation matrices from the real-time PCR data revealed significant multiple associations involving Fusobacterium spp. in combination with P. endodontalis, M. micros and/or Prevotella in the tissue response categories of minimal inflammation, soft and hard disuse degeneration. A positive correlation was also observed between M. micros and P. endodontalis for the category of inflammatory degeneration of the dental pulp. These anaerobes have been strongly implicated in the endodontic infections that occur as sequelae to carious pulpitis. Accordingly, the data suggest that the presence of threshold levels of these bacteria in carious dentine may be indicative of irreversible pulpitis. Knowledge of the microbial predictors associated with irreversible pulpitis creates potential for the development of a diagnostic tool, and for restorative materials with antimicrobial properties.

Master of Dental Surgery / It has been considered for the purpose of this review unnecessary to discuss in detail the Morphology of the dental pulp and dentine, as this may be found in any recognised text-book, but to concentrate on the clinical problems involved. The materials discussed are those in current usage for exposed pulp preservation, whilst other materials may be touched upon and it is the endeavour of the author to review as many results as possible in this field and to draw sound conclusion from statements made. The field of corticosteroids in dentistry is comparatively new and here it is the aim to provide a basis from which further research may be undertaken. Thus, this thesis is divided into two distinct sections. The first section dealing with non-corticoid drugs and the second sections dealing with cortico-steriods and their combinations, exclusively, utilising the commercial product Ledermix as their prime example. However, when considering pulp therapy one must delve into the past to understand the thought and effort that has gone into this realm of dentistry and to note the lack of the true scientific attitude by some into this work. This may then allow us to look again at our own statements to note how much controversy there was, and still is concerning a question such as “should an attempt on the pulp once exposed ever be made to maintain its vitality?” It will be shown at a later stage that the pulp has marvellous recuperating powers if treated in a conservative manner, something which was hardly considered even early this century. Castognola, Quigleyand Berman have all reviewed this subject before. However, my aim is to bring together all of their information as a preface to the important work of considering the immediate study being carried out in this field. The first attempted vital capping was carried out by Philip Pfaff in 1756 with a small piece of gold foil adapted to the base of the cavity. Then in 1826 it was reported that Lenoard Koeker cauterized the exposed pulp with a hot iron wire and placed silver or lead caps over the exposures. It then appeared that little further was written concerning pulp capping until the middle of the 19th century when Albrecht (1856) utilised opiates, caustics and eugenol on the exposed pulp. McKown (1859) recommended cotton soaked in creosote and tannic acid, whilst Taft (1859) was in favour of cauterizing recently exposed pulps with nitric acid and placing a filling immediately. These results were purely a subjective evaluation. In fact Mc Kown’s results were produced on one of his own teeth. The history of pulp preservation really begins in the early 1860’s. Allport (1866) and Atkinson (1866-1868) suggested amputation of all projecting cornua of exposed pulps and placement of a temporary filling until it was healthy. Allport used the b lood clot formed during operation as his means of capping. J Foote (1866) also, believed the blood clot to be the best means of covering the pulp. This certainly appeared to be a reasonable assumption, considering medical knowledge of the day.

Doctor of Philosophy / This work was digitised and made available on open access by the University of Sydney, Faculty of Dentistry and Sydney eScholarship . It may only be used for the purposes of research and study. Where possible, the Faculty will try to notify the author of this work. If you have any inquiries or issues regarding this work being made available please contact the Sydney eScholarship Repository Coordinator - ses@library.usyd.edu.au

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Weyerhaeuser's Paper Mill in Albany, Oregon has been experiencing frequent ring formation in the #3 rotary lime kiln. Rings form when lime mud (CaCO₃) or product lime (CaO) particles adheres to the walls of the lime kiln and become resistant to the abrasive action of the sliding motion of product lime particles (Notidis, 1994). Ring formation has resulted in frequent shut downs to remove (blast) the rings and caused a significant loss of productivity and revenue to the company. A careful analysis of the production process in the mill revealed that concentration of sodium was high and that of sulfur low in the lime mud. The high sodium was due to the low sulfur input to the kiln resulting in high sodium to sulfur ratio. The use of natural gas as a fuel source in the kiln partly causes low sulfur levels in the mud. This study examines the effects of burning emulsified sulfur in the #3 rotary lime kiln to reduce sodium enrichment in the solids, and examine its effect on kiln operation and SO₂ emissions from the #3 rotary lime kiln. A four day trial of burning emulsified sulfur to reduce sodium concentration in the #3 rotary lime kiln was planned. Tote bins of 70% solution of emulsified sulfur was fed into the #3 rotary lime kiln. The sulfur feed was controlled to ensure an excess of sulfur by observing the SO₂ concentration in the kiln stack and maintaining a concentration above 100 ppm corrected to 10% oxygen. The results show that while burning emulsified sulfur had no significant effect on kiln operation, it resulted in a high reduction of sodium in the dust caught in the electrostatic precipitator and an increase SO₂ emission from the stack. The reduction of sodium in the dust was 50%, which is an enrichment factor of 2. Although lime can effectively remove SO₂, the removal efficiency decreased from 96.0% to 73.0% when emulsified sulfur was burned in the #3 rotary lime kiln. The results of this trial are promising, since it demonstrates that burning emulsified sulfur significantly lowers the sodium enrichment in the kiln. The reduced levels of sodium can potentially lead to a reduction in ring formation in the #3 rotary lime kiln in the Albany Paper Mill. / Graduation date: 2004

Graduation date: 1999

Thesis (M.S.)--Brigham Young University. Dept. of Chemical Engineering, 2006. / Includes bibliographical references (p. 75-78).

In January 2005 a trading scheme with emission allowances, including carbon dioxide (CO2), was introduced in Europe. This has influenced the electricity price as well as the price of CO2 emitting production. The paper and pulp industry uses a high share of electricity and emits CO2 and is therefore chosen. This industry is investigated to see if the competitiveness for the industry has been influenced by the emission trading scheme. Since the trial period is too short to give any clear results, USA has been investigated to make comparisons with Sweden. Different theories about the subject together with electricity price and production price data from Statistiska Centralbyrån. A competitiveness model is calculated with help from production prices and show that Sweden has become relatively more competitive compared to the USA since 1995. A reason for this can be the introduction of an emission trading scheme in the USA in 1995. If this is the case, the Swedish paper and pulp industry can face a decrease in competitiveness in the near future.

The experiences of past efforts of industrial pollution control while maintaining competitiveness should be of great value to research and policy practice addressing sustainability issues today. In this article, we analyze the environmental adaptation of the Swedish pulp industry during the period 1970–1990 as illustrated by the sulfite pulp producer Domsjö mill. We investigate how this company managed to adapt to heavy transformation pressure from increasing international competition in combination with strict national environmental regulations during the 1960s to the early 1990s. In line with the so-called Porter hypothesis, the company was able to coordinate the problems that were environmental in nature with activities aiming at production efficiency goals and the development of new products. Swedish environmental agencies and legislation facilitated this ―win-win‖ situation by a flexible but still challenging regulatory approach towards the company. From the early 1990s and onwards, the greening of the pulp industry was also a result of increased market pressure for green paper products.

Petroleum coke (petcoke) has been burned at kraft pulp mills to partially substitute for natural gas and fuel oil used in lime kilns. Due to the high vanadium and sulfur contents in petcoke, there had been concerns over the impact of burning petcoke on kiln and chemical recovery operations. Laboratory studies were performed to examine the fate of vanadium and sulfur in lime kilns and chemical recovery cycle. The results suggest that most of the vanadium in petcoke quickly forms calcium vanadates with lime in the kiln, mostly 3CaO•V2O5. In the causticizers, calcium vanadates react with Na2CO3 in green liquor to form sodium vanadate (NaVO3). Due to its high solubility, NaVO3 dissolves in the liquor circulating around the chemical recovery system. V becomes enriched in the liquor, leading to vanadium build-up in the system. The S in petcoke would stay in the reburned lime, lower the lime availability, increase SO2 emissions from the kiln stack, alter the S balance, increase the liquor sulphidity, and potentially contribute to ring formation in the kiln.