Influence of Different Curing Modes on Polymerization Behavior and Mechanical Properties of Dual-Cured Provisional Resins

Abstract

This study determined the influence of curing mode on polymerization behavior and mechanical properties of dual-cured provisional resins. Three dual-cured bisacryl-based provisional resins were used: Tempsmart (TS; GC Corp), Luxatemp Automix Solar (LX; DMG Chemisch Pharmazeutishe Fabrik GmbH), and Integrity Multi·Cure (IG; Dentsply Caulk). A self-cured bisacryl-based provisional resin, Protemp Plus (PP; 3M ESPE) and a conventional poly(methyl methacrylate) (PMMA) provisional resin, Unifast III (UF; GC Corp) were used as controls. The inorganic filler content and coefficients of linear thermal expansion of the test materials were measured. Six specimens of each material were used to determine the flexural strength, elastic modulus, and resilience. The changes in ultrasound velocity during polymerization were measured. The average inorganic filler contents of the provisional resins, apart from UF, ranged from 24.4 to 39.3 wt%. The highest inorganic filler content was determined for LX, whereas TS showed the lowest value among the tested materials. The average coefficients of thermal expansion of the tested provisional resins ranged from 77.3 to 107.7 (×10/°C). TS and IG showed significantly lower thermal expansions than the other tested provisional resins. The mean flexural strengths of the provisional resins ranged from 70.4 to 122.6 MPa, the mean elastic moduli ranged from 1.8 to 3.7 GPa, and the mean resilience of the provisional resins ranged from 1.1 to 2.3 MJ/mm, respectively. Dual-cured provisional resins showed significantly higher flexural strengths than the PMMA resin. However, in all cases, the light-curing mode showed significantly higher flexural strengths than the self-curing mode. In the initial polymerization phase, dual-cured resins in the light-curing mode showed a rapid increase in the speed of sound (V) during light irradiation, followed by a slower increase. Conversely, the dual-cured resins in the self-curing mode showed a slower initial increase, followed by a rapid increase. Although no significant difference in V was observed between 10 and 15 minutes in the light-curing mode of all tested dual-cured resins, a significantly higher V value was obtained at 15 minutes than at 10 minutes in the self-curing modes for LX and IG. Regardless of the curing mode, tested dual-cured provisional resins showed superior mechanical properties than the conventional PMMA provisional resin. However, dual-cured provisional resin flexural properties and polymerization behavior were affected by the curing mode. This study indicated that the light-curing mode might be recommended for all dual-cured provisional resins because of the enhancement of their mechanical properties and reduction of chair time.

Influence of different curing modes on flexural properties, fracture toughness, and wear behavior of dual-cure provisional resin-based composites

“…Most of the provisional resin-based composites showed decreased values with an increased number of TCs. Shibasaki et al investigated the initial polymerization behavior of these DCPRs using ultrasonic measurement, and reported that all of the DCPRs exhibit a lower polymerization rate with self-curing than with dualcuring 12) . Lower polymerization of DCPRs may lead to higher water absorption, resulting in a lower σF during the course of TCs.…”

“…The σ F and elastic modulus (E) were determined from the stress-strain curve using computer software (Bluehill version 2.5, Instron) linked to the testing instrument. In addition, the modulus of resilience (R) was calculated using the equation: 12) .…”

“…However, some reports have claimed that polymerization initiated by self-curing alone results in poorer mechanical properties than polymerization with light irradiation [13][14][15][16] . Our previous report on dual-cure provisional resin-based composites (DCPRs) indicated that lower σ F values were obtained without light irradiation than with light irradiation 12) . When fabricating provisional restorations with DCPRs either at the chair side or in a dental laboratory, impression materials are often used as an index.…”

“…Recently, bis-acryl-based provisional resinbased composites containing inorganic fillers for the fabrication of provisional restorations have been introduced that exhibit superior mechanical properties and easy handling characteristics [9][10][11] . Several of these new products offer dual-curing modes, enabling the ondemand polymerization of restorations 12) . However, some reports have claimed that polymerization initiated by self-curing alone results in poorer mechanical properties than polymerization with light irradiation [13][14][15][16] .…”

“…Therefore, light irradiation may be a crucial factor affecting the longterm durability of DCPRs. However, little is known about Bis-GMA: bisphenol-A-glycidyl methacrylate; UDMA: urethane dimethacrylate *Inorganic filler contents from previous report 12) the differences in the mechanical and wear properties of DCPRs polymerized using different curing modes with and without light irradiation. In this study, we examined the influence of curing mode under artificial aging on flexural properties and K IC of DCPRs.…”