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 / 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.

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

Thesis (Ph. D.)--Institute of Dental Research, Faculty of Dentistry, University of Sydney, 2002. / Title from title screen (viewed Apr. 23, 2009) Submitted in fulfilment of the requirements for the degree of Doctor of Philosophy to the Faculty of Dentistry. Includes bibliography. Also available in print form.

Thesis (M.S.)--University of Michigan, 1968.

Thesis (M.S.)--University of Michigan, 1958.

Thesis (M.S.)--University of Michigan, 1976.

Thesis (M.S.)--Ohio State University, 2009. / Title from first page of PDF file. Includes vita. Includes bibliographical references (p. 26-30).

Thesis (doctoral)--Karolinska Institutet, Stockholm, 1988. / Extra t.p. with thesis statement inserted. Includes bibliographical references.

Thesis (M.S.)--University of Michigan, 1968.