Effect of extended light activation and increment thickness on physical properties of conventional and bulk-filled resin-based composites

Autor(es)

de Mendonca, Beatriz Curvello ^[1] ; Soto-Montero, Jorge Rodrigo ^{[1, 2]} ; de Castro, Eduardo Fernandes ^[1] ; Kury, Matheus ^[1] ; Cavalli, Vanessa ^[1] ; Rueggeberg, Frederick Allen ^[3] ; Giannini, Marcelo ^[1]

Afiliação do(s) autor(es)

^[1] Univ Estadual Campinas, Piracicaba Dent Sch, Dept Restorat Dent, Operat Dent Div, Av Limeira 901, BR-13414903 Piracicaba, SP - Brazil

^[2] Univ Costa Rica, Sch Dent, Dept Restorat Dent, Montes De Oca, Sj - Costa Rica

^[3] Augusta Univ, Dept Restorat Sci, Dent Coll Georgia, Augusta, GA - USA

• Tipo de documento: Artigo Científico
• Fonte: CLINICAL ORAL INVESTIGATIONS; NOV 2021.
• Citações Web of Science: 0

Resumo

Objectives To evaluate the biaxial flexural strength (BFS), flexural modulus (BFM), and Knoop microhardness (KHN) of incremental and bulk-filled resin-based composites (RBCs) using extended curing exposure times. Materials and methods Disc specimens (n = 8; 6-mm diameter) were fabricated using three stacked molds (0.5-mm thick for the top and bottom molds, and a 1-mm-thick center mold for the conventional and 3-mm thick for the bulk-fill RBCs). Conventional (Tetric EvoCeram/TCE and Filtek Z250/FIZ) and bulk-fill RBCs (Tetric EvoCeram Bulk Fill/TBF and Filtek One Bulk Fill Restorative/FOB) were evaluated. The stacked RBC-filled molds were light-cured for (1) the manufacturer-recommended exposure (MRE) duration; (2) 50%, and (3) 100% extension of the MRE. The BFS, BFM, and KHN of the top and bottom discs were measured. BFS and BFM were analyzed by three-way ANOVA (material{*}curing time{*}depth) and Tukey's post hoc (alpha = 0.05). KHN was analyzed by two-way ANOVA (curing time{*}depth) and Tukey's post hoc (alpha = 0.05). Results Extending the exposure duration did not change the BFS and BFM on the top of the RBCs, but the BFS and KHN increased at the bottom of bulk-fill RBCs. For the conventional RBCs, TCE showed the highest increase on BFS at the bottom, going from 53.6 MPa at T1 to 69.9 at T3. Among the bulk-fill RBCs, FOB presented the highest increase on the bottom BFS (T1: 101.0 +/- 19.9 MPa, T3: 147.6 +/- 12.9 MPa). For all RBCs and exposure times, BFS and KHN were lower at the bottom. Only FIZ and FOB reached a bottom-to-top hardness ratio of 80%, at T3 and T2. Conclusion A significant increase on the BFS and KHN on the bottom of bulk-fill RBCs can be observed when the time of exposure to the curing light is double the MRE. However, extended exposure does not eliminate differences on the BFS and KHN between the shallow and deep regions of RBCs. TCE and TBF failed to reach an acceptable B/T hardness ratio at all evaluated exposure times. (AU)

• Processo FAPESP: 17/04348-2 - Avaliação das propriedades físicas e mecânicas de materiais restauradores do tipo bulk-fill
• Beneficiário: Beatriz Curvello de Mendonça
• Modalidade de apoio: Bolsas no Brasil - Mestrado