Effect of cavity design, placement technique and material on marginal leakage of posterior resin restorations
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Composite resins have gained tremendous popularity during the past few years. So much so, that other conventional anterior restorative materials have been practically replaced. Less desirable physical properties of composite resins prevent their use as posterior restorative materials (Class 1 a Class II). The efforts of this study were to detemine the effect of a variety of factors, i.e., techniques, and materials toward achieving an esthetic posterior restoration. Of 125 human posterior teeth chosen for an in vitro experimental dye-penetration study, three main groups were designated for each of the three restorative materials used. Teeth of Group A were prepared with conventional composite; Group B was prepared with a new composite material (Silane) selected for its improved physical properties; and teeth of Group C were prepared with amalgam serving as a control restorative material. Within each of these three groups, four subdivisions were designated according to the method of cavity preparation utilized. Subgroup 1 was prepared according to the conventional method, without acid-etching and without enamel bonding. Subgroup 2 was prepared like Subgroup 1 with the addition of the acid-etch technique. Teeth in Subgroup 3 were prepared like Subgroup 1, with the addition of both the acid-etch technique and enamel bonding. Subgroup 4 received a modified cavity preparation which utilized less undercutting for greater tooth conservation and included the bevelling of the cavo surface angles and rounding of all the angles. All cavity preparations were Class 1. After completing the restorations of the teeth, a certain number of specimens from each group became the subjects for a dye-penetration study in conjunction with themal cycling. These specimens were then cut longitudinally to observe and photograph evidence of seepage of the dye. Other specimens were sectioned longitudinally for scanning electron microscopy examination of marginal adaptation. The findings indicated the superiority of the modified cavity preparation with the use of acid-etch and the application of a low viscosity sealant. Using a compressive pressure technique with the new composite (Silane) resulted in the best restorations.
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 firstname.lastname@example.org.Photographs, some colored, included.Thesis (M.Sc.D.)--Boston University, Henry M. Goldman School of Graduate Dentistry, 1979 (Prosthodontics)Bibliography: leaves 59-64.
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