Siriwan Kuntharaporn. A comparison in shear bond strength of different adhesives between orthodontic bracket-tooth surfaces and orthodontic bracket-amalgam restorations . Master's Degree(Orthodontics). Mahidol University. : Mahidol University, 2008.
A comparison in shear bond strength of different adhesives between orthodontic bracket-tooth surfaces and orthodontic bracket-amalgam restorations
Abstract:
The objective of this thesis was to compare the shear bond strength (SBS) of
different adhesives between metal orthodontic brackets on tooth surfaces and on
tooth surfaces with amalgam restorations. Two hundred and fifty human upper
premolars extracted for orthodontic purposes were randomly divided into two major
groups; a tooth surface group and a 50% buccal amalgam restoration group.
Brackets were bonded to the teeth using five different adhesives in each groups: I:
UniteTM; II: Rely-a-bond®; III: Enlight®; IV: Transbond XTTM; V: Transbond
PlusTM with self-etching adhesive. The teeth were thermocycled between 5° and 55°
for 500 cycles, and consequently debonded using Instron testing machine to test the
SBS. The enamel surfaces were examined under a stereomicroscope at 25X
magnification and the amount of residual adhesive remaining on the teeth was
determined with Adhesive Remnant Index (ARI) scores. The SBS values of all
adhesives used on tooth surfaces were greater than the bonds of brackets on tooth
surfaces with the amalgam restorations (p<.05). Significant differences among
different adhesives did not exist in the tooth surface group (p>.05), but did exist in
the amalgam restoration group (p<.05), in which Transbond XT and Enlight SBS
values were significantly higher than Unite, Transbond Plus and Rely-a-Bond. In
conclusion, the SBS values on tooth surfaces of all adhesives in this study were
clinically acceptable (5.9-7.8 MPa). Three-step light-cured adhesives (Transbond
XT and Enlight) had clinically acceptable SBS values on tooth surfaces with
amalgam restorations. In a comparison of the ARI scores, all adhesives both on
tooth surfaces and tooth surfaces with amalgam restorations had different failure
modes. Mostly, adhesive failure was found between adhesive/bracket bases on tooth
surfaces, and cohesive failure was found within adhesives on tooth surfaces with
amalgam restorations, with the exception of Transbond Plus, in which the same
failure modes were recorded both on tooth surfaces and tooth surfaces with
amalgam restorations. Failures of the Transbond Plus group occurred mostly within
adhesives and between adhesive/tooth surfaces and amalgams.