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Title: In-vitro assessment of modified resin adhesive-tooth interfaces
Author: Almahdy, Ahmed
Awarding Body: King's College London (University of London)
Current Institution: King's College London (University of London)
Date of Award: 2013
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Objectives: This research aimed to characterize the interfacial characteristics of modified dental resin-based adhesive systems bonded to sound and carious dental tissue. The modification included the incorporation of matrix metalloproteinase (MMP) inhibitors within the primers of these adhesives. Materials and methods: Two MMP inhibitors (BB94 and GM6001) were added to three adhesive primers, Optibond FL “OB” (Kerr, USA), Prime&Bond NT “PB” (Dentsply, USA) and G-Bond “GB” (GC, UK) and bonded to sound dentine. The inhibitory effect of the modified adhesive on recombinant MMPs and on sound dentine MMPs was assessed using FRET-based measurement of MMP activity and substrate zymography, respectively. Micro-tensile bond strength and micro-permeability were used to evaluate the modified adhesives’ physical properties. Micro-Raman spectroscopy analysis was validated on carious dentine and it was used to evaluate the interface between the modified OB primer and caries-affected dentine. The inhibitory effect of the modified adhesive on caries-affected dentine was studied using in-situ zymography. Results: The fluorometric assay and zymography showed that modified adhesives had high affinity toward both synthetic FRET-peptides and dentine powder substrates, respectively. The immediate micro-tensile bond strength was enhanced for OB (48.0 MPa ± 20.3 SD for BB94 and 42.0 MPa ± 18.7 SD for GM6001) and GB (34.8 MPa ± 19.2 SD for BB94 and 41.7 MPa ± 17.6 SD for GM6001). However, no changes were detected between the control and the inhibitor groups following 3-month storage. Additionally, the micro-permeability of PB and GB showed less dye seepage, to the “hybrid layer” and to the “adhesive”, respectively. The caries-infected dentine was defined significantly by the KHN (< 20.6), AF (> 14.4 A.U.) and by the relative contribution of the mineral (< 36.4%), Porphyrin fluorescence (> 25.3%) and Infected dentine signal (> 0.3%) Raman clusters. The caries-affected dentine-adhesive interface exhibited more hydrophobic resin (32.8% ± 3.9 SD) that maintained over four-week aging. Conclusions: The addition of MMP inhibitors to contemporary dental adhesive systems resulted in modified adhesives that had an enhanced dentine-adhesive interface with inhibited MMP activity. Such properties enhance the clinical performance of adhesive systems.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available