Journal of Dental Research, Vol 68, 1124-1131, Copyright © 1989 by International & American Associations for Dental Research Online Journals
A confocal optical microscope study of the morphology of the tooth/restoration interface using Scotchbond 2 dentin adhesive
T. F. Watson
Department of Anatomy and Developmental Biology, University College London, England.
It is difficult to avoid specimen damage when one is preparing an
adhesive/adherend interface for examination using conventional optical or
scanning electron microscopy. Fluorescence imaging with a confocal optical
microscope has facilitated evaluation of the distribution of Scotchbond 2
dentin adhesive, in an in vitro study with P50 composite resin used as the
restorative material. The adaptation of the adhesive and restoration to the
tooth was excellent. Gap formation between the restoration and the tooth
was observed only when the adhesive system was used incorrectly.
Contributions of the primer film former (Scotchprep) and hardening film
former (Scotchbond 2) to the adhesive interface with the tooth and
overlying composite restoration could be identified. The dentin smear layer
was incorporated by the Scotchprep and subsequently impregnated by the
Scotchbond 2. Control of the film thickness was difficult. Cracking and
cohesive failure within the adhesive were observed when the film thickness
exceeded 70 microns, with such thicknesses easily achieved in internal line
angles. The extent of the slippery air-inhibited layer was considerable,
but could be reduced if the adhesive was wiped with a cotton wool pledget.
The distribution of the Scotchbond 2 within the tooth was localized to the
smear layer and dentin up to 50 microns deep to it. This study has shown
the penetration of Scotchbond 2 dentin adhesive within the tooth and its
distribution within the restoration.
