Abstract
The aim of this research was to evaluate the load cycling influence in resin composite restorations through marginal leakage analysis, in enamel and cementum. Forty bovine incisors were allocated in four groups (n=10): I – Z250 resin composite / Single Bond adhesive system; II – Charisma resin composite / Gluma One Bond adhesive system; III - Z250 resin composite / Single Bond adhesive system submitted to 1,000 cycles (10Kgf); group IV - Charisma resin composite / Gluma One Bond adhesive system submitted to 1,000 cycles. The class V restorations were located at cementum-enamel junction and the load was applied on the incisal edge. The samples were immersed in 2% buffered methylene blue solution. The samples were cross-sectioned and the leakage, which received a score, was evaluated through stereomicroscope (45 X ). Data were submitted to Kruskal-Wallis’ test (5%). Analysis showed no statistical differences among margins localized in enamel or in cementum, for loaded and unloaded groups (p>0,05). However, enamel showed better results than cementum in the same sample (p<0,05).Load cycling did not increase the microleakage in enamel or in cement margins. Comparing the infiltration degree in the same sample, the staining solution penetration was higher in cementum margins, for both loaded and unloaded groups.
Highlights
Tooth-colored restorative materials based on dimethacrylate monomers have increasingly been used to replace missing tooth structures and to modify tooth esthetics
There were no differences (p>0.05) among the groups restored with Z250/Single Bond and the Picture 2 – Microleakage of resin composite Z250
The etiology of non-carious cervical lesions indicated that incisal or occlusal loads might induce compressive stress at the dentin-enamel junction in the cervical region (LEE & EAKLE14, 1984) and the plastic or elastic deformation of restored teeth by these tension could lead to bond failure at the margins of the restorations (QVIST20, 1983)
Summary
Tooth-colored restorative materials based on dimethacrylate monomers have increasingly been used to replace missing tooth structures and to modify tooth esthetics. The linking of fillers and matrix through a silane agent. The matrix consists of organic monomers, a polymerization inhibitor, and an activation/initiation system (ANUSAVICE1, 1998). The resin matrix is a fluid component that becomes rigid when polymerized. It is due to the free radical formation that induces covalent linking between the organic molecules. These unions lead to macromolecules formation named polymers (GUGGENBERGER & WEINMANN10, 2000). During this connection formation there is some volumetric reduction of the material.
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