Original Article

Hardness and Depth of Cure of Conventional and Bulk-fill Composite Resins in Class II Restorations with Transparent and Metal Matrix Strips

Bulk-fill Composites in Class II Restorations


Objectives: Hardness is relevant to the degree of conversion (DC) and depth of cure (DoC). The aim of this study was to determine the micro-hardness and DoC of conventional and bulk-fill composite resins in class II restorations using metal and clear matrix bands.

Materials and Methods: Twelve specimens of each of the two composite resins, i.e., Filtek Z350 XT bulk-fill and Gradia posterior conventional composite, were prepared in the form of a class II cavity in a tooth mold, using a clear or metal matrix band. All specimens were cured and stored at 37°C for 24 hours. Vickers hardness was measured as a function of DoC at 2mm intervals. Data were analyzed by two-way ANOVA (alpha=0.05).

Results: The bulk-fill composite exhibited significantly higher hardness levels than the conventional composite in all tested surfaces (P<0.001). However, while the metal matrix band had a significant impact on the bottom surface (P=0.059) and also on the furthest surface from the matrix and light source (P=0.04), it did not have a consistent effect across all tested surfaces. The simultaneous interaction of the composites and matrix band types in all surfaces, did not show significant differences in hardness values. The highest bottom-to-top surface hardness ratio (73%) was observed in the conventional composite near the metal matrix band.

Conclusion: In deep class II cavities, the bottom-to-top surface hardness ratio did not reach the maximum of 80%, neither for bulk-fill nor conventional posterior composites. Therefore, in such cavities extended light-curing and more incremental composite placement is needed.

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IssueVol 20 (Continuously Published Article-Based) QRcode
SectionOriginal Article
DOI https://doi.org/10.18502/fid.v20i20.12912
Composite resins Dental Cavity Preparation Hardness Tests

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Musavinasab S, Norouzi zahra. Hardness and Depth of Cure of Conventional and Bulk-fill Composite Resins in Class II Restorations with Transparent and Metal Matrix Strips. Front Dent. 2023;20.