Search

The purpose of this study was to investigate the protective effect of a glass ionomer cement (GIC) consisting of fluoro-zinc-silicate glass on the demineralization of bovine dentin using the ultrasonic pulse-echo method. The findings were compared with those obtained using a conventional GIC. Slabs of dentin from bovine teeth were sliced, shaped into a rectangular form, and immersed in 0.5 M ethylenediaminetetraacetic acid solution at 25ºC for 6 days, followed by storage in distilled water for 3 days. After demineralization, they were immersed in artificial saliva with and without the GIC specimens. The propagation times of the longitudinal ultrasonic waves in the samples were measured. The ultrasonic velocities of the fluoro-zinc-silicate glass-containing GICs were significantly increased 2-3 days after the start of the experiment and showed an upward trend thereafter. These findings indicate that the GICs containing fluoro-zinc-silicate glass might exhibit the potential to promote remineralization in the dentin. [ABSTRACT FROM AUTHOR]

Objective: To examine the effect of filler contentTo examine the effect of filler content on structural coloration of experimental flowable resin composites. Overview: Experimental composites containing spherical fillers and different filler contents (30, 40, 50, 60 and 70 wt%), a structural colored resin composite (Omnichroma), and a nanohybrid flowable resin composite (Gracefil LoFlo) were used. The optical characteristics of the specimens were measured on standard black and white backgrounds using a spectrophotometer under CIE D65 illuminant and the L*a*b* values were determined. The color matching abilities to artificial teeth were evaluated using the ΔE*ab and ΔE00 color difference formulas. One‐way analysis of variance and Tukey's post hoc test were used. The spectral reflectance of experimental composites showed different trends in different backgrounds, plate thickness, and filler contents. In particular, higher spectral reflectance was observed on the white background at wavelengths ranging from 450 to 700 nm in both 1.5 and 3.0 mm plates when compared to the black background. The percent reflectivity tended to decrease with a decrease of the filler contents. The color matching abilities of the experimental composites improved with the increase in the filler contents. Conclusions: Structural coloration of the flowable resin composites were affected by the filler contents. Clinical significance: Clinical Significance: Higher filler contents might be needed to achieve the optimal color properties of structural colored flowable resin composites, thereby improving the restoration esthetics. [ABSTRACT FROM AUTHOR]

Objectives: This study evaluates the effect of self-assembling peptide P11-4 (Curodont Repair, CDR) on bovine enamel remineralization by measuring changes in ultrasonic propagation velocity.Methods: Six specimens per group were prepared by sectioning bovine teeth into enamel blocks. These blocks were then immersed in lactic acid buffer solution (pH = 4.75) for 10 min twice a day and stored in artificial saliva. Other specimens were first treated with CDR, followed by a 10-min immersion in the lactic acid buffer solution twice a day, before storage in artificial saliva. The propagation time of longitudinal ultrasonic waves was measured using a pulser/receiver. Six specimens were used for each treatment protocol. The obtained data were statistically analyzed using ANOVA followed by Tukey's honestly significant difference tests (α = 0.05). Specimens were observed using laser scanning microscopy and scanning electron microscopy.Results: Sonic velocity was found to decrease with time for specimens stored in the demineralizing solution. On the other hand, increases in sonic velocity were found for specimens treated with CDR. These specimens also exhibited signs of mineral deposition.Conclusions: By measuring the ultrasonic propagation velocity, it can be concluded that CDR application has an ability to promote bovine enamel remineralization. [ABSTRACT FROM AUTHOR]

Objective. To use ultrasonic measurements to monitor the effects of adhesive application and power density on the polymerization behavior of dual-cured core build-up resins. Methods. Ultrasonic measurements were carried out using a pulser-receiver, transducers and an oscilloscope. The core build-up resins were mixed, inserted into a transparent mold and then placed onto a sample stage with or without self-etch adhesive. Power densities of 0 (no light irradiation), 200 and 600 mW/cm2 were used for curing. The transit time through the core build-up resin disk was divided by the specimen thickness to obtain the longitudinal sound velocity (V). Results. Light irradiation of the core build-up resins at a power density of 600 mW/cm2 caused V values to rise to an initial plateau of 1550-1650 m/s, then to rise rapidly to a second plateau of 2800-3200 m/s. The rate of V increase was slower when the resin cements were light-irradiated and became faster when irradiated at a higher power density. There were no significant differences between the groups with or without adhesive. Conclusions. The polymerization behavior of the core build-up resins was affected by the power density of the curing unit. The influence of adhesive application differed among the core build-up resins tested. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the influence of utilizing films with different oxygen transmission rates (O2-GTR) on Knoop hardness and toothbrush abrasion of resin cements for luting. Methods: Four dual-activated, composite-type resin cements, and a chemically activated PMMA-type resin cement, were used. Three different types of barrier films (Techbarrier HI, Harden Film N130, and Lix-2) were used. Resin cement was mixed and inserted into a cylindrical mold (4 mm in diameter, 3 mm in height), then chemically activated. The specimens were stored in the dark at 37±1°C, 90±5%RH conditions for 1 hour. Knoop hardness on the top surface of the resin cement was measured with a micro-hardness tester. The top surface of specimens (8 mm in diameter, 3 mm in height) polymerized under the same conditions were used for toothbrush abrasion testing. One-way ANOVA followed by Tukey HSD test (P< 0.05) were done. Results: When the cement surface was covered by low O2-GTR film, a significant increase in Knoop hardness and resistance to toothbrush abrasion was observed for the dual activated, composite-type resin cements, but not for the chemically activated PMMA type resin cement. From the results of this study, the use of low O2-GTR matrix harder films for the dual activated, composite-type resin cements could be effective in eliminating the oxygen inhibited layer on the cement surface. [ABSTRACT FROM AUTHOR]

Objective Materials and Methods Results Conclusions The color matching of single‐shade resin composites after in‐office whitening was investigated.Four single‐shade resin composites were used. A total of 35% hydrogen peroxide was used as the whitening agent. The resin composite was placed in a cavity of an artificially discolored bovine tooth. The color differences between the restoration and surrounding enamel before and after whitening were determined based on ΔE*ab, ΔE00, and ΔWID. The color stability, surface roughness (Sa), and surface gloss (GU) of the resin composite alone were also evaluated. Statistical analyses were performed using repeated‐measures analysis of variance with the Tukey–Kramer test.Based on the 50:50% of perceptibility and acceptability thresholds of ΔE*ab and ΔE00, none of the resin composite restorations were clinically acceptable before or after whitening. Regarding ΔWID, although all resin composites showed “acceptable match” in the baseline, they showed “mismatch” after the third session of whitening. Most of the resin composites alone were stable in color against whitening.Although the single‐shade resin composites failed to achieve the expected color matching on discolored teeth either before or after the whitening, the impact of the whitening on the color of the resin composite alone may be negligible. [ABSTRACT FROM AUTHOR]