A long-term clinical evaluation of a high copper alloy vs a lathe cut amalgam

PLEASE NOTE: This work is protected by copyright. Downloading is restricted to the BU community: please click Download and log in with a valid BU account to access. If you are the author of this work and would like to make it publicly available, please contact open-help@bu.edu.Black and white SEMicrographs included.Thesis (M.Sc.D.)--Boston University, Henry M. Goldman School of Graduate Dentistry (Operative Dentistry Specialty), 1980.Bibliography: leaves 76-80.Even though dental materials are in a state of flux and many new materials are being introduced, amalgam is still the most popular dental restorative material currently used by the dental profession. The available brands, according to the advertisements, are improved and render superior restorations. However, the question still arises, what amalgam to choose. Essentially two systems are marketed: lathe-cut alloys and spherical alloys. The question arises whether either system will yield superior results over the other if all clinical factors are considered optimal and when long term function is being considered. For that purpose the following investigation was conducted. Patients from two offices were used for this study. In office B lathe-cut alloy (Velvalloy) had been used for more than ten years. Office A exclusively restored teeth with Dispersalloy amalgam. The clinical competence of both operators was indisputable and both were considered superior practitioners, who routinely practice under rubber dam and polish their restorations whenever possible. In office A, 33 at random selected patients and 27 patients of office B coming in for their bi-annual recall, were utilized for this study. Clinical evaluation of all existing amalgam restorations completed by the operators, was done by means of the U.P.H.S. system designed by Ryge (1973). Every quadrant was photographed and subsequently replicated according to an intraoral replica technique developed by Pameijer (1979) (54). The laboratory phase consisted of processing the impressions and viewing in a scanning electron microscope. After the scanning electron microscope phase was completed, all specimens were measured at 60x at random selected areas, by means of a stereo dissecting microscope. In order to get more feedback on the clinical evaluations of the investigator, three operators evaluated the clinical photographs during a slide presentation and rated them according to the J.S.P.H. All data from the clinical evaluation, scanning electron micrographs, light microscope and slide presentation were collected, analyzed and correlated