Polymerization depths of conventional and bulk fill composites photoactivated by different methods

Abstract

The aim of this study was to evaluate the depth of cure of conventional (Filtek Z350 and Esthet-X HD) and bulk fill resins composites (Filtek bulk fill flow and SDR) using different photoactivation methods. Samples were made using five discshaped matrices (1 mm high and 8 mm central diameter) with interposed polyester strips. The samples were photoactivated using different methods [continuous high-irradiance light (LCA), continuous low-irradiance light (LCB), and soft-start (SS)], maintaining 24 J/cm² radiant exposure. After 24h, Knoop microhardness test was performed at 5 depths (surface, 1 mm, 2 mm, 3 mm and 4 mm). The Knoop microhardness were analyzed by ANOVA two-way and Tukey's test (5%). Conventional resins presented the highest results up to 2 mm depth, except for Esthet-X photoactived by LCB, which showed significant lower Knoop hardness from 2 mm depth. Bulk fill resins photoactivated with LCA and SS had the highest results in 4 mm depth. The LCA and SS photoactivation methods produce suitable photoactivation in conventional composites up to 2 mm and bulk fill up to 4 mm depth and the bulk fill composites present higher polymerization depth than conventional composites.

Influence of different power densities during polymerization on the color of composite resins

“…The International Commission of L'Eclairage developed the system to measure colors based on human perception (CIE L*, a*, b*). The variable L* corresponds to the black-white luminosity coordinate, a* indicates the color coordinate along the red-green axis, and b* indicates the color coordinate along the yellowblue axis [19,20]. A positive ΔL value means that the object tends to white (brighter) and negative Δb and Δa values mean that the tooth tends to be less yellow and less red, respectively [21].…”

“…The color stability of composite resins depends on the degree of conversion of monomers into polymers throughout a sufficient polymerization [8,16,17] and it is affected by the system and the technical condition of polymerization [18]. The delivered radiant exposure and the power density of the photopolymerizer should agree with the energy requirement of the resin so there is a complete conversion of monomers into polymers [19,20]. The higher the power density, the higher the number of photons and the greater is the depth and effectiveness of polymerization [21].…”

Effect of Light Emitting Diode (LED) Curing Modes on Depth of Cure (DoC) in BulkFill Composite Resin: an invitro study

“…7 Recent advances in polymer science have led to the introduction of newer bulkfill composite, SureFil smart dentin replacement (SDR) Flow (DENTSPLY Caulk, Milford, DE, United States) that claim to be able to cure up to 4mm depth compared to that of conventional composites, and is, therefore, advocated to be used in posterior teeth. 8,9 The unique combination of high filler loading with modified resin provides high DoC in SDR composites than the conventional ones. 10 This allows the placement of an increment >2.0mm.…”