Date of Award

Spring 2006

Document Type

Thesis - Restricted

Degree Name

Master of Science (MS)

Department

Dentistry

First Advisor

Lobner, Doug

Second Advisor

Bradley, Thomas G.

Third Advisor

Lobb, William K.

Abstract

Advances in stem cell research, have made the prospect of regenerating tissue a clinical reality, with one potential application being in the field of dentistry. Recently stem cells have been discovered in pulpal tissue. Exploiting the ability of these stem cells to differentiate into odontoblasts, could potentially heal pulpally involved teeth. Cariously involved teeth have diminished amounts of normal dentin that may lead to exposure of the pulp to the oral environment, which left untreated will result in either extraction or endodontic therapy. Odontoblasts secrete dentin, which can bridge the exposure of the pulp to the oral environment providing a possible alternative treatment to aforementioned treatment modalities. Before odontoblastic treatments can be fully implemented, further studies need to be conducted to understand the potential toxicity of dental materials to these cells and the growth factors necessary for stem cells to differentiate into odontoblasts. The aim of this project was to study the in vitro effects of two classes of dental restorative materials, amalgam and composites, on glial cells, pure neuronal cultures, mouse embryonic stem cells, and dental pulp stem cells. Some amalgams contain zinc, which has been shown to mediate the toxicity of amalgam to fetal murine neuronal cells. The current study will determine whether amalgam containing zinc is more toxic to the dental pulp stem cells than zinc-free amalgam. The toxicity of fully set composite to the dental pulp stem cells is unknown. Based on the results of these experiments, the least toxic amalgam and composite will be further studied on dental stem cells treated with growth factors. We will test the effects of Insulin-Like growth factor (IGF), epidermal growth factor (EGF) and basic fibroblastic growth factor (bFGF) on dental pulp stem cells. The dental pulp stem cells were obtained from extracted unerupted third molars. The extracted teeth were debrided and the crown was surgically removed using a sterile diamond burr. The exposed pulp was carefully removed from the pulp chamber. The pulpal tissue was digested to harvest the cells which were plated to allow the dental cells to proliferate. These cells were treated with the two dental restorative materials for a 24- hour period followed by MIT cytotoxicity assays were performed. Further, the dental pulp cells were treated with IGF, bFGF or EGF followed by treatment with amalgam or composite for a 24-hour period followed by MTT cytotoxicity assay was performed...

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