Pong Pongprueksa. Effect of elastic cavity wall and occlusal loading on microleakage and bond strength of class V restorations . Master's Degree(Operative Dentistry). Mahidol University. : Mahidol University, 2006.
Effect of elastic cavity wall and occlusal loading on microleakage and bond strength of class V restorations
Abstract:
The objective of this study was to evaluate the effect of an unfilled-adhesive
resin (Adper™ Single Bond) and a filled-adhesive resin (Adper™ Single Bond 2)
with and without a low viscosity resin (Filtek™ Flow) as an elastic cavity wall in
class V composite restorations on marginal leakage and ultimate bond strength. V
shaped cavities were prepared on buccal surfaces of 64 premolars, lined with either
unfilled or filled adhesives with and without low viscosity resin, and restored with a
resin composite. The restored teeth in each group were divided into two subgroups
for unloaded and loaded conditions. Two specimens from each group of unloaded
condition were evaluated for the elastic modulus with nano-indentation test at the
layer of dentin, hybrid layer, adhesive resin, low viscosity resin and resin
composite. The remaining specimens were subjected for dye leakage test and
micro-tensile bond strength test.
The results demonstrated that the elastic moduli were significantly different
among layers (p<0.05) except between hybrid layers of unfilled and filled adhesive
(p=1.0). In all groups, dentin margin had significantly higher microleakage than
that on enamel margin (p<0.05). No statistically significant differences of the
enamel microleakage were found between unloaded and loaded groups for all
materials (p=0.512) but significant differences on the dentin margins were found in
groups which low viscosity resin was used (p<0.05). Significant differences of the
microtensile bond strength were found between unfilled-adhesive and filledadhesive
group with low viscosity resin (p = 0.016) under unloaded condition.
Under loaded condition, there were no significant differences in bond strength
between unfilled and filled adhesive group whether low viscosity intermediate layer
was used. The effect of occlusal loading on the bond strength was found in the
group using filled adhesive without intermediate layer (p=0.031).
The results of this study suggested that the application of filled adhesive or
low viscosity resin as elastic cavity wall had no influence on the marginal leakage
of both enamel and dentin margins. However, it had an influence on the dentin
microtensile bond strength of class V composite restorations.