Journal of Dental Research, Vol 73, 1079-1087, Copyright © 1994 by International & American Associations for Dental Research Online Journals
SEM evaluation of the resin-dentin interface with proprietary bonding agents in human subjects
P. R. Walshaw and D. McComb
Restorative Department, Faculty of Dentistry, University of Toronto, Ontario, Canada.
Laboratory studies on dentin bonding do not replicate physiological
reality. This study examined with SEM the attachment produced in vivo under
clinical conditions. Forty-four cavities were prepared in buccal/lingual
surfaces of 16 premolar teeth scheduled for extraction and assigned
randomly for treatment with: All-Bond 2 (Bisco) (A) with and (B) without
dentin etch, (C) Scotchbond 2 (3M), (D) Scotchbond Multi-Purpose (3M), and
(E) controls, using Enamel Bond (Kulzer) with dentin etch. After atraumatic
extraction, restorations were split transversely by freeze-fracture and
acid-treated. SEM examination of A revealed significant areas of gap-free
attachment, with evidence of an acid-resistant hybrid layer (5-8 microns),
often with resin tags of various lengths. Resin-reinforced collagen fibers
were seen. Gap formation was coincident with lack of bonding resin layer
over primed dentin. Attachment with B was less effective; a hybrid layer
was infrequently seen and few resin tags. Pooled bonding resin at internal
line angles appeared to favor an effective bond. Treatment C resulted in
large areas of detachment, leaving an adherent primed dentin layer with
short resin tags. Treatment D revealed significant areas of gap-free
attachment and evidence of a hybrid layer. Controls (E) showed total bond
failure. Attachment with A and D was secure, restorations remaining in situ
even after freeze-fracture. This study confirmed that brief acid
pre-treatment of dentin, allowing diffusion of resin-dentin primers,
appeared conductive to development of an effective bond in vivo, similar to
that reported in vitro.
