Document Type

Thesis

Date of Degree

Spring 2012

Degree Name

MS (Master of Science)

Degree In

Oral Science

First Advisor

Steven R. Armstrong

Abstract

In vivo and in vitro degradation of resin-dentin interfaces can occur and accounts for poor clinical performance of adhesive dentin interfaces/restorations. Interfacial degradation results from several factors, to include, but not limited to: water sorption, hydrolysis of ester linkages of methacrylates resins, and activation of endogenous dentin matrix metalloproteinases (MMPs) in non-infiltrated collagen fibrils. Reduction of collagenolytic and gelatinolytic activity in dentin has been shown to be effective both in vivo and in vitro upon application of proteases inhibitors, such as chlorhexidine. This study compared the in vitro durability of resin-dentin bonds using microtensile testing over 12-month of water storage among five adhesive systems, including an experimental adhesive system, which had 2% chlorhexidine incorporated into the material. The results showed that all adhesive systems had a significant decrease in bond strength after 6 months, and that this reduction in bond strength was not significant different among the five adhesive systems studied. It is possible that chlorhexidine might have its inhibitory activity against MMPs lost or reduced due to chemical interaction with the adhesive system components. Also, to assess resin-dentin bonds degradation process, laboratorial studies use long-term water storage, which is labor-intense and time consuming process, therefore this study tested the possibility of accelerating the resin-dentin degradation process using water storage at 50° C. A significant reduction in microtensile bond strength occurred for specimens after 12-month storage at 50° C. The higher temperature may have increased the rate of water sorption and hydrolytic activity within the polymer network leading to adverse consequences to the interface.

Keywords

chlorhexidine, degradation, high temperature, microtensile, self-etching, storage

Pages

xi, 146 pages

Bibliography

Includes bibliographical references (pages 127-140).

Comments

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Copyright

Copyright 2012 Gizele M R Geraldeli

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