Thesis (M.S.)--University of Michigan, 1959.

Thesis (M.S.)--University of Michigan, 1984.

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

Thesis (M.S.)--Marquette University, 1997.

Thesis (M.S.)--University of Michigan, Ann Arbor, 1978. / Typescript (photocopy). Includes bibliographical references (leaves 59-61).

Thesis (M. D. S.)--University of Hong Kong, 2009. / Includes bibliographical references (p. 111-119).

Thesis (doctoral)--University of Oslo, 1980. / Includes reprints of 7 papers by author.

Investigou-se o efeito da radiopacidade de diferentes materiais obturadores sobre a sensibilidade, especificidade e confiabilidade da análise radiográfica de obturações endodônticas. Após determinação da radiopacidade dos materiais, um total de 80 dentes caninos tiveram seus canais radiculares preparados com a técnica clássica antes de serem divididos em 5 grupos cada qual a ser obturado com um dos cimentos obturadores estudados (AH Plus, Endomèthasone®, Sealer 26, Acroseal e cimento não-radiopaco). Antes do preenchimento com a técnica de condensação lateral da guta-percha, em metade dos dentes de cada grupo, inseriu-se um fio de nylon radiolúcido (Ø 0.25 mm), ao longo do canal radicular para simular um defeito de obturação (n=8). Um total de 36 dentes molares superiores, depois de instrumentados, foram divididos em 3 grupos cada qual a ser obturado com um dos cimentos testados (AH Plus, Acroseal e cimento não-radiopaco) (n=12). Antes da obturação com a mesma técnica utilizada nos caninos, um fio de 0.08 mm de espessura foi estendido no canal disto-vestibular de cada dente. Após a utilização de artifícios para simular a sobreposição dos tecidos humanos, os dentes obturados foram radiografados e as imagens periapicais analisadas por endodontistas e radiologistas quanto à presença de defeitos de preenchimento nas obturações. Após análise estatística empregandose os testes exato de Fisher, Kappa e teste t (p<0.05). Observou-se menor sensibilidade no exame dos dentes anteriores obturados com os cimentos radiopacos, principalmente na avaliação dos radiologistas, e identificou-se maior especificidade para as obturações efetuadas com os cimentos endomethasone® e Acroseal. No julgamento dos dentes posteriores, o cimento Acroseal proporcionou menor sensibilidade do que o AH Plus e houve menores valores de especificidade na avaliação dos endodontistas, embora sem diferenças entre os grupos de cimentos estudados. A confiabilidade mostrou-se maior para as obturações dos caninos realizadas com Endomethasone® e Sealer 26 e não se detectaram diferenças entre os grupos na avaliação das obturações dos molares. Concluiu-se que a radiopacidade dos cimentos influenciou na sensibilidade, especificidade e confiabilidade da análise radiográfica de obturações endodônticas, assim como a especialidade dos examinadores. / The aim of this study was to investigate the effect of different radiopaque sealers in the sensitivity, specificity and realiability of radiographic root canal filling exam. After radiopacity distinction of root canal sealing materials, a total of 80 extracted single-rooted upper canines had their canals prepared with classic technique before being divided into 5 groups, each to be filled with one of the tested sealers (AH Plus, Endomèthasone®, Sealer 26, Acroseal and non-radiopaque sealer). In half specimens a radiolucent nylon monofilament string (Ø 0.25 mm) positioned inside the root canal to simulate a radiolucent void before being filled with gutta percha lateral condensation (n=8). A total of 36 maxillary molars were divide into 3 groups, each to be filled with one of the tested sealers (AH Plus, Acroseal and non-radiopaque sealer). Before being filled with lateral condensation technique, a Ø 0.08mm string was positioned alongside distobuccal root canal. After root canal filling, each tooth was strictly positioned in a device to simulate bone and soft tissue before being exposed to X rays. The resulting images were interpreted for presence of voids by radiologists and endodontists. The differences between groups were assessed using Fisher Exact, Cohens Kappa and t test (>0.05). There were less sensitivity for all radiopaque sealers, specially for radiologists, and higher specificity when Endomethasone® and Acroseal were used to fill the upper canines. Root canal fillings performed in maxillary molars with Acrosel showed lower sensibility values than AH Plus mainly to endodontists, but no difference in specificity between groups. There were lower reliability than control group for canines filled with Endomethasone® and Sealer 26. The differences of reliability between groups were not statistically significant. It was concluded that radiopacity of sealers influenced on sensitivity, specificity and reliability of radiographic root canal filling exam, as well as the speciality of examiners.

Magister Scientiae Dentium - MSc(Dent) / Statement of problem: Although bioceramic endodontic sealer cements offer various advantages over conventional zinc oxide-based and resin-based cements, questions have been raised about the ability to retreat root canals that have been sealed using these cements. Aims and Objectives: The aim of the study was to determine the retreatability of root canals sealed using a bioceramic calcium silicate-based sealer cement. The objectives were to determine the possibility of achieving working length and apical patency when obturation is done with the master GP placed at working length and when it is short by 3mm. The time it took to achieve these parameters when it was possible to achieve them was also determined. The role of XP Endo Finisher R, a supplementary retreatment file, in achieving working length and apical patency was also to be evaluated. However, this latter aspect was eliminated after the pilot study, when it was found not to have an effect in regaining working length and apical patency.

The main objective of root canal therapy is cleaning, shaping and obturating the root canal system in three dimensions, as well as preventing reinfection. The objective of this in vitro study was: <ul> <li>to establish the antimicrobial efficacy of nine different root canal irrigation solutions, </li> <li>to determine the smear layer dissolving capabilities of these irrigating solutions, at various levels in straight root canals, and </li> <li>to examine the degree of erosion caused by the irrigation solutions on the root canal walls. </li></ul> Antimicrobial Effects: In this test the antimicrobial activity of nine irrigation solutions against E. faecalis was measured using a disc diffusion test. The antibacterial activity of materials was apparent from circular clear inhibition zones forming around the filtration paper. Effect on Smear Layer: Root canals were prepared by using Pro Taper nickel titanium rotary files. During preparation, the canals were irrigated with copious amounts of 3.5% sodium hypochlorite for 15 minutes. Thereafter, the teeth were randomly divided into nine groups. One group was kept as control. The other eight groups received a final rinse with one of the following irrigation solutions: 18% EDTA, Sterilox, Top Clear 17% EDTA, 2% Chlorhexidine, 10% Citric acid, Biopure MTAD, Ozonated water and Smear Clear. A total of 25ml of each solution was utilized to irrigate each root canal system, and left undisturbed in the root canal for 2 minutes. Biopure MTAD was left in the root canals for 5 minutes. Finally, the irrigation solutions were removed from the root canals with 10ml sterile distilled water. Each root was sectioned horizontally with a diamond disc in sections corresponding with the coronal, middle and apical levels of the root canal system. Each fragment was fractured laterally and prepared according to standard methods for biological SEM evaluation. The absence or presence of the smear layer as well as the amount of erosion of the peritubular dentine was assessed. The One-way ANOVA test was used to determine whether there were any statistical significant differences between the different test groups. No significant inhibition of E. faecalis was observed with sterile water (control) and the undiluted solutions of Sterilox, 10% Citric acid and Ozonated water. However, 3.5% NaOCl, 18% EDTA, Top Clear 17% EDTA, 2% Chlorhexidine, Biopure MTAD and Smear Clear showed significant inhibition of E. faecalis. For the 1/10 diluted solutions no inhibition of E. faecalis was observed with sterile water (control), 3.5% NaOCl, Sterilox, 10% Citric acid and Ozonated water. Biopure MTAD and Smear Clear demonstrated significant inhibition of E. faecalis compared to 18% EDTA, Top Clear 17% EDTA and 2% Chlorhexidine. Biopure MTAD was the only solution that showed significant inhibition of E. faecalis using a 1/100 diluted solution. No inhibition was observed with the 1/1000 diluted test solutions.Scanning electron microscope examination revealed that 3.5% NaOCl and Ozonated water had no visible effect on the smear layer. The 10% Citric acid solution slightly modified the smear layer at the coronal and middle levels of the root canals. There was no visible effect on the smear layer at the apical levels. Sterilox and 2% Chlorhexidine removed the smear layer at the coronal levels, modified it slightly in the middle levels and left the smear layer undisturbed in the apical levels of the root canals. 18% EDTA, Top Clear 17% EDTA, Biopure MTAD and Smear Clear removed the smear layer completely at the coronal levels. At the middle and apical levels of the root canals most of the smear layer was removed. However, there were less open dentinal tubules visible at the apical levels compared to the samples examined at the middle levels of the root canals. It was also noted that Top Clear 17% EDTA caused a significantly high percentage of erosion of the peritubular dentine at the coronal levels of the root canals compared to all the other irrigation solutions. Considering all the results of the present study Biopure MTAD demonstrated the best antimicrobial activity against E. faecalis, and removed most of the smear layer at all three levels of the root canal systems without significant erosion of the peritubular dentine. / Dissertation (MSc(Odont))--University of Pretoria, 2008. / Community Dentistry / unrestricted