Composite Replacement of Amalgam Restoration versus Freshly Cut Dentin: An in vitro Microleakage Comparison.
Abstract: Objective: To evaluate the microleakage of the composite restoration when bonded to a cavity previously restored with amalgam material compared to that of freshly cut dentin. Materials and Methods: Thirty extracted intact human molars were mounted in autopolymerizing acrylic resin. Class II box preparations were prepared on occluso-proximal surfaces of each tooth (4 mm bucco-lingual widt... read moreh and 2 mm mesio-distal depth) with the gingival cavosurface margin 1 mm above the CEJ. Each cavity was then restored using high copper amalgam restoration (Disperalloy, Dentsply) then thermocycled for 10000 thermal cycles. The amalgam restorations were then carefully removed and replaced with Filtek Supreme Ultra Universal, 3MUniversal, ESPE except five of them, which were used for the SEM and EDS analysis. A cavity of the same dimensions was prepared on the other side of the tooth and restored with composite resin then they were thermocycled for 5000 thermal cycles. Twenty samples were randomly selected for dye penetration test using silver nitrate to detect the microleakage. The specimens were analyzed with a stereomicroscope at a magnification of 20x. All of the measurements were done in μm; two readings were taken for each cavity at occlusal and proximal margins. Two measurements were taken using 0 to 3 scale and the percentage measurement. Results: Corrosion products were not detected in both groups (fresh cut dentin and teeth previously restored with amalgam). No statistically significant difference between the microleakage of the two groups was found using a 0 to 3 scale at the occlusal margins (McNemar's test, p= 0.727) or proximal margins (Wilcoxon signed-rank test, p = 0.174). No significance difference was found between the two groups using the percentage measurements and Wilcoxon signed-rank test at either the occlusal (p=0.675) or proximal (p=0.513) margins. However, marginal microleakage was statistically significant between the proximal and occlusal margins (P < 0.001). Conclusion: Within the limitations of this in-vitro study, no significant difference was found between the microleakage of non-discolored dentin in teeth that were previously restored with amalgam compared with freshly cut dentin. However, marginal microleakage in the proximal surface was higher than that in the occlusal surface.
Thesis (M.S.)--Tufts University, 2014.
Submitted to the Dept. of Posthodontics.
Advisor: David Bardwell.
Committee: Hans-Peter Weber, Samer Khayat, Ala Ali, and Matthew Finkelman.
Keyword: Dentistry.read less