Acta Biomaterialia Odontologica Scandinavica最新文献

Purpose: The goal of this investigation was to characterize the compliance properties in selected polymers used for temporary (provisional crown and bridge) applications. Method: Polymethyl methacrylate (PMMA)- and polyethyl methacrylate (PEMA)-based JET and TRIM II were investigated along with two bisacryl composite resins (LUXATEMP and PROTEMP 3 GARANT). Rectangular samples of the resins were subjected to creep-recovery tests in a dynamic mechanical analyzer at and near the oral temperature (27 °C, 37 °C and 47 °C). The instantaneous (elastic), and time-dependent viscoelastic, and viscoplastic compliance profiles of the materials were determined and analyzed as a function of materials and temperature. Results: Highly significant (p = 0.0001) differences among means of elastic, viscoelastic and viscoplastic compliance values were found as a function of materials. TRIM II showed an order of magnitude higher viscoplastic deformation than the other three materials (LUXATEMP, PROTEMP 3 GARANT and JET). Conclusions: The results indicate that PEMA is susceptible to significantly greater elastic, viscoelastic, and more importantly to viscoplastic compliant behavior compared with bisacryl composite and PMMA provisional crown and bridge materials. This indicates high-dimensional instability and poor stiffness and resiliency in PEMA appliances vis-à-vis those of PMMA and bisacryl composites.

Objective: This study used the 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) method to evaluate the percentage of antioxidant activity (%AA) of green tea (GT) and sodium ascorbate (SA) gel in three concentrations (10%, 20% and 30%), and the influence of these concentrations on the microshear bond strength (μ-SBT) values of bleached enamel, using 10% carbamide peroxide (CP). Materials and methods: Eighty intact third molars were selected to perform the μ-SBT test, and were randomly divided into eight experimental groups: G1: positive control - no treatment; G2: negative control - bleached with CP; G3: PC +10% GT; G4: PC +20% GT; G5: PC +30% GT; G6: PC +10% SA; G7: PC +20% SA and G8: PC +30% SA. After applying the treatments, adhesive procedures were performed using Single Bond 2 and Filtek Z350XT. After 24 h, the samples were tested in a universal testing machine until fracture. The %AA was assessed in triplicate by DDPH method using a UV-VIS spectrophotometer. Results: In the μ-SBT, ANOVA revealed no significant difference between the antioxidants evaluated (p = .625), but did reveal significant effects of the concentrations studied (p = .007). A negative correlation was observed between μ-SBT and solution concentrations. The values of %AA were from 90.58 to 96.75. Conclusions: The reverse results occurred in μ-SBT values, only when the antioxidants were used in a 10% concentration and, %AA did not influence μ-SBT.

Objective: The aim of this in vitro study was to evaluate the color stability of different restorative materials (one microfilled composite, one nanofilled composite, one nanohybrid composite and one Ormocer-based composite) after exposure to different staining solutions (coffee, coca-cola and red wine). Material and methods: All materials were polymerized into silicon rings (2 mm ×6 mm ×8 mm) to obtain specimens identical in size. Thirty cylindrical specimens of each material were prepared. They were immersed in staining solutions over a 28-day test period. A colorimetric evaluation according to the CIE L*a*b* system was performed by a blind trained operator at 7, 14, 21, 28 days of the staining process. The Shapiro-Wilk test and Kruskal-Wallis ANOVA were applied to assess significant differences among restorative materials. The paired t-test was applied to test which CIE L*a*b* parameters significantly changed after immersion in staining solutions. Results: All restorative materials showed clinically perceptible color differences after immersion in coffee. L* and b* values showed the highest variability. Coca cola and red wine did not influence the color stability for all restorative materials except for Filtek Supreme XTE. Conclusions: Coffee caused a significant color change in all types of tested composite resins. Filtek Supreme XTE demonstrated alone a staining susceptibility to red wine; no other significant differences among the materials were demonstrated. Long-term exposure to some food dyes (coffee in particular) can significantly affect the color stability of modern esthetic restorative materials regardless of materials' different composition.

Objective: To study the effect of two different microemulsions containing Beackea frutescence supplements composed of nerolidool, selenium and vitamin E on absorption effect related to skin health and skin aging. Materials and methods: A total of 39 volunteers with normal and healthy skin were divided into three groups (n = 13) and supplemented for a period of 12 weeks. Group 1 received a mixture of lutein (3 mg/day), lycopene (3 mg/day), α-tocopherol (10 mg/day), selenium (75 μg/day) and β-nerolidool (4.8 mg/day) and Group 2 was supplemented with a mixture of β-nerolidool (4.8 mg/day), lycopene (6 mg/day), selenium (75 μg/day) and α-tocopherol (10 mg/day). Group 3 was the placebo control. Wrinkling, smoothness, scaling and roughness of the skin were determined by Surface Evaluation of Living Skin (Visioscan). Results: Upon supplementation, serum levels of selected nerolidool increased in both groups. Skin thickness and density were determined by ultrasound measurements. A significant increase for both parameters was determined in the serum groups. Roughness and scaling were improved by the supplementation with antioxidant micronutrients. In the placebo group, no changes were found for any of the parameters. Conclusion:Beackeafrutescence microemulsion supplements have shown significant change in the texture of human skin as well as scaling, wrinkling, smoothness and roughness were improved by the supplementation.

Objective: The aim of the present study was to compare the effect of pre-treating dentin with chlorhexidine, at concentrations of 0.2% and 2%, and remineralizing paste containing CPP-ACP (MI Paste - GC) on the bond strength of adhesive systems. Material and methods: In total, 80 slides of dentin were used. These slides were 2 mm thick and were obtained from bovine incisors. Standard cavities were created using diamond bur number 3131. In the control groups, a Scotchbond Universal Adhesive (SUA) self-etching adhesive system of 3M ESPE and a Clearfil SE Bond (CSE) adhesive system of Kuraray were applied, following the manufacturer's instructions. In the other groups, dentin was pretreated with chlorhexidine (0.2% and 2%) for 1 min and with MI Paste for 3 min. The cavities were restored with Z350 XT resin (3M ESPE). After 24 h of storage, the push-out test was applied at a speed of 0.5 mm/min. Results: The different dentin pretreatment techniques did not affect the intra-adhesive bond strength. There was a difference between treatment with MI Paste and chlorhexidine 0.2% in favor of the SUA, with values of 15.22 and 20.25 Mpa, respectively. Conclusions: The different pretreatment methods did not alter the immediate bond strength to dentin. Differences were only recorded when comparing the adhesives.

Objective: To evaluate the antimicrobial properties and dental pulp stem cells (DPSCs) cytotoxicity of synthesized carboxymethyl cellulose-silver nanoparticles impregnated on titanium plates. Material and methods: The antibacterial effect of silver nanoparticles in a carboxymethyl cellulose matrix impregnated on titanium plates (Ti-AgNPs) in three concentrations: 16%, 50% and 100% was determined by adding these to bacterial cultures of Streptococcus mutans and Porphyromonas gingivalis. The Ti-AgNPs cytotoxicity on DPSCs was determined using a fluorimetric cytotoxicity assay with 0.12% chlorhexidine as a positive control. Results: Silver nanoparticles in all concentrations were antimicrobial, with concentrations of 50% and 100% being more cytotoxic with 4% cell viability. Silver nanoparticles 16% had a cell viability of 95%, being less cytotoxic than 0.12% chlorhexidine. Conclusions: Silver nanoparticles are a promising structure because of their antimicrobial properties. These have high cell viability at a concentration of 16%, and are less toxic than chlorhexidine.

This study determined the influence of coating with either petroleum jelly or light-cured varnish and storage medium on the flexural strength of glass-ionomer cements (GIC). The flexural strength of two glass-ionomer cements (Fuji Equia Fil and Ketac Molar Aplicap) was measured. Specimens (2 × 2 × 25 mm) were prepared in three groups: uncoated, coated with petroleum jelly, or coated with light-cured varnish (EquiaCoat) cured for 20 s using a cure lamp (Bluephase G2, Ivoclar Vivadent, Schaan, Liechtenstein). Specimens were stored for 1 week at 37 °C in water, artificial saliva or 20 mmol dm^-3 lactic acid, then flexural strength was determined in 3-pont bend. Data were analyzed by ANOVA and Tukey HSD post hoc test (p < 0.05). In addition, the mold was filled with water and the temperature change caused by the cure lamp was measured with a thermocouple. For both materials, storage in water gave the lowest flexural strength. It was slightly higher in either saliva or lactic acid, and was improved by coating in petroleum jelly. Specimens coated with light-cured varnish, that also involved heating with a cure lamp, gave the highest flexural strength. The heating effect of the lamp was demonstrated by the temperature rise in the water in the mold after light exposure from 21.9 (± 1.0) °C to 26.8 (± 1.0) °C. hence, sealing of GIC from aqueous media improves flexural strength. The cure lamp emitted heat, which may enhance the flexural strength of specimens coated with light-cured varnish.

Objective To analyze bond strength to bleached enamel following application of 10% sodium ascorbate gel. Material and methods Forty third molars were allocated into five groups (n = 8): GP - unbleached specimens restored with composite resin; GN - specimens restored immediately after bleaching; and G15; G30 and G60 (test groups) - bleached specimens treated with 10% sodium ascorbate gel for 15, 30 and 60 min before restoration. The teeth were sectioned and the buccal and lingual faces were restored. After storage in distilled water (37 °C/24 h), sticks of ±0.8 mm² were tested in tensile (0.5 mm/min). Fractures were observed and classified. Data (in MPa) were analyzed with one-way ANOVA and Tukey tests (α = 0.05). Results No differences were found among GP (26 ± 6.0), G15 (23 ± 7.3), G30 (25 ± 6.1) and G60 (25 ± 5.1), with GN (15 ± 5.5) showing the lowest bond strength (p < 0.0001). Conclusion The application of 10% sodium ascorbate gel for 15 min after bleaching with 37.5% hydrogen peroxide restored the bonding to enamel.

Objective The aim of this study was to evaluate and compare the 5-year survival and complication rate of metal-ceramic (MC) and composite single crowns performed within Public Dental Service, general dentistry, in three Swedish counties and with patients' gender, tooth position, root canal treatment and the presence of a post-and-core taken into account. Methods Data were collected from dental records of 600 patients who had received either an MC (n = 300) or a composite (n = 300) crown on a premolar or molar tooth in the year 2005 and where 5 years of follow-up data were available. Status at treatment completion and at follow-up was recorded, together with any history of intervention during the follow-up period. Results The 5-year survival rate for MC crowns was higher than for composite crowns (93% versus 70%; p < 0.001). This difference was stable, irrespective of the county, patients' gender or tooth position. No gender difference in survival rate was seen for MC crowns, while the survival of composite crowns was significantly higher among women than among men (75% versus 65%; p < 0.05). For MC crowns, there was a tendency toward a lower survival rate for endodontically treated teeth without a post-and-core (83%) as compared to those provided with a post-and-core (93%) and to vital teeth (94%). Surviving composite crowns had recordings of significantly more complications than MC crowns (p < 0.001). Conclusion On premolars and molars, MC crowns have a better medium-term prognosis and fewer complications than composite crowns.