When restoring anterior teeth using resin composites, the use of silicone guide matrices obtained from diagnostic wax-ups is recommended, as this technique facilitates layering and optimizes working ...time. This is particularly important in polychromatic layering and when more than one anterior tooth is to be restored with resin composites. However, in cases of fractured anterior teeth, it is often not feasible to perform a previous impression and waxing. In these cases, due to trauma and related psychological aspects, patients usually seek immediate esthetic solutions. Therefore, an interesting restorative approach that can simplify the restorative technique is the creation of a silicone guide matrix obtained from the patient's fractured tooth, without the need for prior waxing. This type of personalized matrix was initially proposed by Bertholdo, Ricci, and Barrote. Thus, the purpose of the present work is to demonstrate a modification of the technique for making this type of custom-made matrix for the restoration of two upper central incisors of a 14-year-old patient who fractured his teeth in a bicycle accident.
A reliable and validated protocol for nondestructive analysis of the entire restorative interface that could be applicable in studies assessing the adaptation of direct and indirect restorations is ...lacking.
The purpose of this in vitro study was to validate a 3D protocol for microleakage assessment in class II mesio-occluso-distal (MOD) cavities restored with composite resin.
Sixteen human third molars received standardized class II MOD preparations with cervical margins located 1 mm apical to the cemento-enamel junction. The specimens were restored with Filtek Bulk Fill Posterior (FBP) or Filtek Bulk Fill Flowable (FBF) and submitted to 10 000 thermocycles (5 °C and 55 °C with a 30-second dwell time at each temperature and 5-second transfer time). The specimens were scanned with microcomputed tomography (μCT) before and after immersion in 50% ammoniacal silver nitrate solution for 12 hours. Scanned data were processed, and the 3D amount of infiltrated silver nitrate was analyzed through the entire adhesive interface. In addition, the linear distance of silver nitrate infiltration was assessed using 3 axial images obtained from each specimen proximal box (2D analysis). Data were tested for homogeneity by using the Shapiro-Wilk test and evaluated by using 1-way ANOVA, followed by the post hoc Tukey HSD test (α=.05).
FBP showed significantly lower leakage than FBF for both 2D and 3D analyses. A low correlation was observed between the assessment methods.
Three-dimensional analysis of microleakage using μCT is a predictable and more reliable method for nondestructive and comprehensive analysis of the entire specimen.
•Hybrid-fibers (inorganic-organic) are potential reinforcement for dental materials.•Niobium is promising as filler into fibers to improve mechanical properties.•SBS method fabricates non-woven ...fibers with small diameters in a rapid technology.
In this study hybrid nanofibers embedded with niobium pentoxide (Nb2O5) were synthesized, incorporated in self-adhesive resin cement, and their influence on physical-properties was evaluated.
Poly(D,L-lactide), PDLLA cotton-wool-like nanofibers with and without silica-based sol–gel precursors were formulated and spun into submicron fibers via solution blow spinning, a rapid fiber forming technology. The morphology, chemical composition and thermal properties of the spun fibers were characterized by field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDS) and Fourier-transform infrared spectroscopy (FTIR), and differential scanning calorimetry (DSC), respectively. Produced fibers were combined with a self-adhesive resin cement (RelyX U200, 3M ESPE) in four formulations: (1) U200 resin cement (control); (2) U200+1wt.% PDLLA fibers; (3) U200+1wt.% Nb2O5-filled PDLLA composite fibers and (4) U200+1wt.% Nb2O5/SiO2-filled PDLLA inorganic–organic hybrid fibers. Physical properties were assessed in flexure by 3-point bending (n=10), Knoop microhardness (n=5) and degree of conversion (n=3). Data were analyzed with One-way ANOVA and Tukey’s HSD (α=5%).
Composite fibers formed of PDLLA-Nb2O5 exhibited an average diameter of ∼250nm, and hybrid PDLLA+Nb2O5/SiO2 fibers were slightly larger, ∼300nm in diameter. There were significant differences among formulations for hardness and flexural strength (p<0.05). Degree of conversion of resin cement was not affected for all groups, except for Group 4 (p<0.05).
Hybrid reinforcement nanofibers are promising as fillers for dental materials. The self-adhesive resin cement with PDLLA+Nb2O5 and PDLLA+Nb2O5/SiO2 presented superior mechanical performance than the control group.
Highlights • The presence of monomers with acidic groups in self-adhesive resin cements allows a simplified indirect luting technique. • The same acidic monomers may adversely affect their ...properties where the passage of light is inefficient or absent. • The incorporation of nanostructures into dental polymers has shown promising results.
Purpose
To evaluate the color change caused by post‐irradiation conversion (ΔE24h and ΔE8 days) and artificial aging (ΔEAGING) of resin cements light activated through ceramics of different opacities ...immediately and 6 minutes after manipulating the material.
Materials and Methods
Resin cement disks (Allcem and LuxaCore) were light activated through ceramics (without ceramic, e.max HT, LT, and MO) immediately and 6 minutes after the manipulation (n = 10). Spectrophotometry was used to evaluate ΔE24h and ΔE8 days after 37˚C‐dry‐dark‐storage for 24 hours and 8 days, and ΔEAGING after 60˚C‐water‐storage for 24 hours. Data were analyzed with three‐way ANOVA and Tukey's HSD (α = 0.05).
Results
Regarding the post‐irradiation color change, significant differences were found between the cements (p < 0.0001), light activation protocols (p = 0.037), and ceramics (p < 0.001). The immediate activation (16.2 ± 0.1) showed lower ΔE values than the delayed activation (16.5 ± 0.1). Ceramics influenced the ΔE values as follows: MO (14.0 ± 1.2) < LT (14.9 ± 1.2) ≈ HT (15.4 ± 1.2) < control (21.2 ± 1.2). Regarding ΔEAGING, significant differences were found between cements (p < 0.001), light activation (p = 0.006), and ceramics (p < 0.001). The delayed activation (8.4 ± 0.1) showed lower values than the immediate activation (8.9 ± 0.1). Ceramic spacers influenced ΔEAGING as follows: control (5.6 ± 0.2) < MO (6.6 ± 0.2) < HT (11.0 ± 0.2) ≈ LT (11.5 ± 0.2).
Conclusion
The delayed light activation resulted in increased color stability, while the ceramic interposition resulted in lower color stability.
The experiments of aerial photogrammetry using UAV and aircraft are demonstrated to compare their performance and resolution. Instruments used for the aircraft photogrammetry is commercial product ...digital camera. This is much lower-cost than professional photogrammetry instruments, however the results shows enough quality for information gathering in the initial stage of disaster response. On the other hand, The UAV aerial photo sharing web system "UAV oblique photo browser" has been newly developed as a light weight and simple system that is useful in the initial stage of disaster response.
The objective of this study was to evaluate the influence of adhesives with different 10-MDP concentrations on the shear bond strength of a resin cement to zirconia.
Six experimental adhesives were ...prepared with the following composition: camphorquinone, 1,2-diaminobenzene, butylhydroxytoluene, diphenyliodonium hexafluorophosphate, 2-hydroxyethyl methacrylate triethylene glycol dimethacrylate, ethoxylated bisphenol A glycol dimethacrylate, urethane dimethacrylate, bisphenol A diglycidyl methacrylate, and ethanol. The 10-methacryloyloxydecyl dihydrogen phosphate (10-MDP) monomer was added at 0wt%, 3wt%, 6wt%, 9wt%, 12wt%, or 15wt%. Three commercially available adhesives were evaluated: Single Bond Universal, Single Bond 2, and Signum Zirconia Bond. Resin cement cylinders made with RelyX Ultimate were bonded to yttria-stabilized tetragonal zirconia polycrystal with one of the evaluated adhesives and were subjected to the shear bond strength evaluation. Failure modes were analyzed with a stereoscopic loupe. Statistical analyses were performed with one-way analysis of variance and the Tukey's Honestly Significant Difference test (α=0.05). Pearson's was used to correlate the percentage of 10-MDP in the experimental adhesives and shear bond strength.
There were significant differences between adhesives (p<0.00001). The highest shear bond strength values were obtained with the Signum Zirconia Bond and Single Bond Universal. Single Bond 2 showed the lowest values. There were no differences between experimental adhesives. All groups showed adhesives failures. A nonlinear correlation was found between bond strength and percentage of 10-MDP in experimental adhesives (r=0.872).
The commercially available adhesives indicated for bonding to zirconia showed the highest bonding values.
The restoration of single discolored maxillary anterior teeth is still a difficult task, as not only shape and surface characterization play an important role in the success of the treatment, but the ...propagation of light throughout the restorative material does as well. In some cases, small changes in morphology, color, and brightness will be noticeable. These factors are sometimes very tricky, and shade guides alone are difficult to use for color selection. This article proposes a protocol of employing cross-polarization imaging for improving the accuracy of the shade selection of resin composites. The step-by-step technique is presented for the restoration of a single discolored tooth.
Abstract Objectives To evaluate the influence of different tertiary amines on degree of conversion (DC), shrinkage-strain, shrinkage-strain rate, Knoop microhardness, and color and transmittance ...stabilities of experimental resins containing BisGMA/TEGDMA (3:1 wt), 0.25 wt% camphorquinone, 1 wt% amine (DMAEMA, CEMA, DMPT, DEPT or DABE). Different light-curing protocols were also evaluated. Methods DC was evaluated with FTIR-ATR and shrinkage-strain with the bonded-disk method. Shrinkage-strain-rate data were obtained from numerical differentiation of shrinkage-strain data with respect to time. Color stability and transmittance were evaluated after different periods of artificial aging, according to ISO 7491:2000. Results were evaluated with ANOVA, Tukey, and Dunnett's T3 tests ( α = 0.05). Results Studied properties were influenced by amines. DC and shrinkage-strain were maximum at the sequence: CQ < DEPT < DMPT ≤ CEMA ≈ DABE < DMAEMA. Both DC and shrinkage were also influenced by the curing protocol, with positive correlations between DC and shrinkage-strain and DC and shrinkage-strain rate. Materials generally decreased in L * and increased in b *. The strong exception was the resin containing DMAEMA that did not show dark and yellow shifts. Color varied in the sequence: DMAEMA < DEPT < DMPT < CEMA < DABE. Transmittance varied in the sequence: DEPT ≈ DABE < DABE ≈ DMPT ≈ CEMA < DMPT ≈ CEMA ≈ DMAEMA, being more evident at the wavelength of 400 nm. No correlations between DC and optical properties were observed. Significance The resin containing DMAEMA showed higher DC, shrinkage-strain, shrinkage-strain rate, and microhardness, in addition to better optical properties.
The present in vivo randomized, triple-blinded, and split-mouth clinical study evaluated the effectiveness of a hybrid light (HL) source on the color change, stability, and tooth sensitivity in ...patients submitted to different in-office bleaching techniques. Twenty volunteers were divided into two groups and four subgroups. A split-mouth design was conducted to compare two in-office bleaching techniques (with and without light activation): 35% Lase Peroxide Sensy (LPS) + HL: 35% hydrogen peroxide (HP) + HL; 35% LPS: 35% HP; 25% LPS + HL: 25% HP + HL; and 35% Whiteness HP (WHP): 35% HP. For the groups activated with HL, the HP was applied on the enamel surface three consecutive times using a 3 × 2-minute protocol (three HL activations for two minutes each, with a 30-second interval for a total of seven minutes and 30 seconds) for each gel application, totaling 22 minutes and 30 seconds. For the other groups, HP was applied 3 × 15 minutes, totaling 45 minutes. A spectrophotometer was used to measure the color change (ΔE) before the treatment and 24 hours, one week, and one, 12, and 36 months after. A visual analog scale was used to evaluate the tooth sensitivity before the treatment, immediately following treatment, 24 hours, and one week after. Analysis of variance, Tukey's, Kruskall-Wallis, and Wilcoxon tests, all with α = 0.05 were performed. Statistical analysis did not reveal any significant differences (ΔE) between the in-office bleaching techniques with or without HL in the periods evaluated; the activation with HL required 50% less time to achieve such results. The groups without HL presented statistical differences for ΔE when comparing 24 hours with the other follow-up times (intergroup) and an increase in tooth sensitivity in the initial periods. All techniques and bleaching agents were effective on bleaching during a 36-month evaluation of color stability. The groups activated with HL presented lower sensitivity and required a lower activation time.
PDF
