Master of Dental Surgery / The lack of adaptation between restorative materials and tooth structure has for many years been a major problem in Dentistry. Studies during this time have emphasized that the margins of restorations are not fixed, inert and impenetrable borders, but dynamic microcrevices which contain a busy traffic of ions and molecules (Going, 1972). The microleakage which results, has been defined as “the clinically undetectable passage of bacteria, fluids and molecules or ions between a cavity wall and the restorative materials applied to it” (Kidd, 1976, b). Microleakage has been implicated in a variety of clinical conditions, including recurrent caries, tooth discolouration, hyper-sensitivity, pulp pathology and hastened breakdown of restorative materials (Kidd, 1976, a and b; Torney et al, 1977). Buonocore (1955) was probably the first to bond resins to tooth structure, etched by the application of phosphoric acid to enamel surfaces. It was found that etching the enamel converted a previously hydrophobic, low energy surface to a more wettable high energy state possessing an increased surface area with numerous retentive sites for resin tag formation. Over the years, the acid-etch technique has been used in a number of dental procedures including fissure sealing, the repair of fractured incisal edges, the repair of hypoplastic and abraded areas, the placement of orthodontic brackets and the splinting of teeth. In recent years, studies have evaluated the ability of the acid-etch technique to improve both the adaptation and retention of composite resins to tooth structure and the marginal seal around composite restorations. However, much of the research examining adaptation of composite resins to tooth enamel has been limited to the study of the enamel tooth surface rather than the enamel of the cavity wall. In addition, previous studies have paid little attention to the effects, on the microleakage, of different etching times and different sizes of the inorganic filler particles and to the influence of aging the restorations on the microleakage. The review of the literature also indicated some controversy concerning the use and effectiveness of low viscosity resins. Since the early 1970’s acid-etching of the enamel has been used increasingly in the placement of composite resin restorations, to provide retention and to minimize marginal microleakage. It was the purpose of this investigation to examine the etched enamel cavity wall, to compare the ability of composite resins, of different particle size and viscosity, to adapt to this cavity wall, and to study the influence, in vitro, of these and other factors, on the microleakage occurring at the margins of restoration.

Master of Dental Surgery / The lack of adaptation between restorative materials and tooth structure has for many years been a major problem in Dentistry. Studies during this time have emphasized that the margins of restorations are not fixed, inert and impenetrable borders, but dynamic microcrevices which contain a busy traffic of ions and molecules (Going, 1972). The microleakage which results, has been defined as “the clinically undetectable passage of bacteria, fluids and molecules or ions between a cavity wall and the restorative materials applied to it” (Kidd, 1976, b). Microleakage has been implicated in a variety of clinical conditions, including recurrent caries, tooth discolouration, hyper-sensitivity, pulp pathology and hastened breakdown of restorative materials (Kidd, 1976, a and b; Torney et al, 1977). Buonocore (1955) was probably the first to bond resins to tooth structure, etched by the application of phosphoric acid to enamel surfaces. It was found that etching the enamel converted a previously hydrophobic, low energy surface to a more wettable high energy state possessing an increased surface area with numerous retentive sites for resin tag formation. Over the years, the acid-etch technique has been used in a number of dental procedures including fissure sealing, the repair of fractured incisal edges, the repair of hypoplastic and abraded areas, the placement of orthodontic brackets and the splinting of teeth. In recent years, studies have evaluated the ability of the acid-etch technique to improve both the adaptation and retention of composite resins to tooth structure and the marginal seal around composite restorations. However, much of the research examining adaptation of composite resins to tooth enamel has been limited to the study of the enamel tooth surface rather than the enamel of the cavity wall. In addition, previous studies have paid little attention to the effects, on the microleakage, of different etching times and different sizes of the inorganic filler particles and to the influence of aging the restorations on the microleakage. The review of the literature also indicated some controversy concerning the use and effectiveness of low viscosity resins. Since the early 1970’s acid-etching of the enamel has been used increasingly in the placement of composite resin restorations, to provide retention and to minimize marginal microleakage. It was the purpose of this investigation to examine the etched enamel cavity wall, to compare the ability of composite resins, of different particle size and viscosity, to adapt to this cavity wall, and to study the influence, in vitro, of these and other factors, on the microleakage occurring at the margins of restoration.

Thesis (M.D.S.)--University of Sydney, 1981. / Title from title screen (viewed Apr. 23, 2009) Submitted in fulfilment of the requirements for the degree of Master of Dental Surgery to the Faculty of Dentistry. Degree awarded 1981; thesis submitted 1980. Includes diagrams and tables. Includes bibliography. Also available in print form.

published_or_final_version / abstract / Dentistry / Master / Master of Dental Surgery

published_or_final_version / abstract / Dentistry / Master / Master of Dental Surgery

<p>The aim of this study was to determine whether the presence or absences of the root canal seal had any influence on the retrograde sealing ability of MTA (mineral trioxide aggregate).</p>

Thesis (M. D. S.)--University of Hong Kong, 2006. / Title proper from title frame. Also available in printed format.

<p>The aim of this study was to determine whether the presence or absences of the root canal seal had any influence on the retrograde sealing ability of MTA (mineral trioxide aggregate).</p>

Thesis (M. D. S.)--University of Hong Kong, 2008. / Also available in print.

Thesis supervisor: Saulo Geraldeli. Includes bibliographic references (p. 66-70).