Abstract
ObjectiveTo evaluate the gingival marginal seal in class II composite restorations using different restorative techniques.Material and MethodsClass II box cavities were prepared in both proximal faces of 32 sound human third molars with gingival margins located in either enamel or dentin/cementum. Restorations were performed as follows: G1 (control): composite, conventional light curing technique; G2: composite, soft-start technique; G3: amalgam/composite association (amalcomp); and G4: resin-modified glass ionomer cement/ composite, open sandwich technique. The restored specimens were thermocycled. Epoxy resin replicas were made and coated for scanning electron microscopy examination. For microleakage evaluation, teeth were coated with nail polish and immersed in dye solution. Teeth were cut in 3 slices and dye penetration was recorded (mm), digitized and analyzed with Image Tool software. Microleakage data were analyzed statistically by non-parametric Kruskal-Wallis and Mann-Whitney tests.ResultsLeakage in enamel was lower than in dentin (p<0.001). G2 exhibited the lowest leakage values (p<0.05) in enamel margins, with no differences between the other groups. In dentin margins, groups G1 and G2 had similar behavior and both showed less leakage (p<0.05) than groups G3 and G4. SEM micrographs revealed different marginal adaptation patterns for the different techniques and for the different substrates.ConclusionThe soft-start technique showed no leakage in enamel margins and produced similar values to those of the conventional (control) technique for dentin margins.
Highlights
The gingival margins of class II restorations are critical to the bonding process because of minimal or total absence of enamel
The main reason for failure of direct composite restorations has been related to the secondary caries[12], which still has been associated to both, poor marginal adaptation and sealing[14]
The internal angles were rounded and cavosurface margins were finished with gingival margin trimmers[6]
Summary
The gingival margins of class II restorations are critical to the bonding process because of minimal or total absence of enamel. The composite resin polymerization shrinkage can produce the breakdown of the adhesive bonds. Marginal gaps may occur and induce tooth sensitivity and pulpal damages. The main reason for failure of direct composite restorations has been related to the secondary caries[12], which still has been associated to both, poor marginal adaptation and sealing[14]. The open sandwich technique, using glass ionomer cement (GIC) and composite resin, has been suggested as a better option to the conventional composite resin technique[2,11]. The GIC is capable of chemically reacting with calcium ions present in the tooth structure creating a bond between them, providing a better and long-lasting
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