American journal of dentistry最新文献

Purpose: To evaluate staining- and aging-dependent changes in the color and translucency of 3D-printed resin-modified ceramics (RMC).

Methods: Specimens (n= 5 per condition and material) were fabricated from test materials: Permanent Crown Resin (PCR), Crowntec (CT), Vita Enamic (VE) and Tetric CAD (TC). Specimens were stained in wine, coffee, tea, and water (control) and exposed to artificial accelerated aging (AAA). Color measurements were obtained using a spectrophotometer at baseline (T0) and at 3.5 (T1) and 7 (T2) days after immersion. For AAA, measurements were obtained at baseline (T0) and after exposure to controlled irradiance of 150 kJ/m² (T1) and 300 kJ/m² (T2). Mean and standard deviations were calculated on CIEDE2000 color differences (ΔE₀₀), translucency parameter (TP₀₀) and treatment-dependent changes in the translucency parameter (ΔTP₀ ₀). Differences between materials and test conditions were tested by one-way ANOVA (α= 0.05). Results were additionally interpreted using visual color difference thresholds in dentistry ΔE₀₀= 0.8 for the 50:50 perceptibility threshold (PT) and ΔE₀₀= 1.8 for the 50:50 acceptability threshold (AT). ΔTP₀₀ values were interpreted using 5058;50 TPT₀₀= 0.6 and 50:0% TAT₀₀= 2.6.

Results: Statistically significant differences were found among the materials when exposed to the different test conditions. At the T0-T1 time interval, the highest color difference was found with wine (0.1-2.2) on all materials except CT, which showed the highest ΔE₀₀ with AAA (2.5). The second highest color differences were obtained upon exposure to AAA (0.2-2.5) and tea (0.5-1.1). The TP₀₀ at baseline ranged from 5.1 to 9.8. Significant differences in ΔTP₀₀ were found among the tested materials and staining/aging conditions, but no significant differences were found among the staining/aging intervals (T0-T1, T0-T2 and T1-T2).

Clinical significance: Staining- and artificial aging-dependent changes of 3D-printed and milled resin modified ceramics used for definitive restorations could represent a challenge in terms of restoration acceptability or dissatisfaction. Staining and aging conditions produced significant color changes, while translucency changes were not significant.

Purpose: To evaluate and compare the effects of different scaling and polishing techniques on the surface roughness of four different restorative materials.

Methods: 72 specimens were prepared, molded to a size of 8.0 by 2.0 mm, and cured according to the manufacturers' instructions. The specimens were stored at 37°C for 24 hours and then thermocycled for 5,000 cycles (from 55°C to 5°C) to simulate 6 months of clinical use. Surface roughness (Ra/average and Rz/max-overall heights) was calculated using a stylus profilometer by subtracting the simulated treatments of hand scaling, ultrasonic scaling, and air polishing from the baseline measurements. The difference in Ra and Rz data were compared independently for each measurement using a two-way ANOVA on Ranks and the Holm-Sidak test, with α< 0.05 used to determine significance.

Results: Irrespective of the scaling or polishing technique employed, flowable bulk fill demonstrated the lowest Ra and Rz values. Hand scaling exhibited the highest roughness and variability among the other techniques, regardless of the materials tested (P< 0.001). Air polishing with glycine resulted in the lowest roughness values across all tested materials, with the exception of the tested bioactive restorative material group.

Clinical significance: Regarding surface roughness, air polishing with glycine may be an effective and safe intervention for periodontal maintenance of subgingival restorations compared to the other tested scaling methods.

Purpose: To evaluate over time the bond strength to dentin of different resin composites (RBCs) associated with the universal adhesive system applied with self-etching or total-etching strategies.

Methods: 60 human third molars were obtained, randomly divided into experimental groups (n= 10) according to RBCs: methacrylate-based nanofilled (Z350 XT); low-viscosity Ormocer-based bulk-fill (Admira Fusion X-base Universal); or high-viscosity Ormocer-based bulk-fill composite (Admira Fusion X-tra). The adhesion procedure was performed using a universal adhesive (Futurabond U) applied in self-etching or total-etching mode. Occlusal preparations (Class I) were made, measuring 4 mm in mesiodistal length, 4 mm in depth, and 3 mm in buccolingual height. The cavities were restored considering the RBCs and adhesive strategies, and the light curing was performed using a LED unit (BluePhase) as recommended by the manufacturers. For this, the nanofilled RBCs were inserted by the oblique incremental technique while the bulk-fill RBCs were inserted in single increments. The samples were stored in water for 24 hours in an oven; to be sectioned, the sticks were randomly separated, stored in distilled water for 24 hours (immediate) or 12 months (long-term), and taken to the universal machine for a microtensile test (MPa). The fractured sticks were examined to classify the type of fracture. The results were analyzed by ANOVA and Tukey's test (α= 0.05).

Results: The MPa values of methacrylate-based nanofilled or high-viscosity Ormocer-based RBC were not affected by the strategy used to apply the universal adhesive system (P> 0.05). However, for the low-viscosity Ormocer-based RBC, higher values were obtained when the total-etching strategy was used compared to the self-etching mode (P< 0.05). After 12 months, when using the total-etching strategy low-viscosity Ormocer-based RBC, higher MPa values were obtained compared to the other materials (P< 0.05).

Clinical significance: Regardless of the adhesive strategy used, the high-viscosity RBCs, whether based on methacrylate or Ormocer, showed similar adhesive behavior. Low-viscosity Ormocer-based RBC showed greater long-term bond strength associated with the universal adhesive applied in the total-etching strategy.

Purpose: To evaluate the effect of different varnishes on dentin permeability to erosive/abrasive challenges.

Methods: 60 superficial dentin discs were randomly allocated to six groups (n=10): Duraphat, PRG Barrier Coat, Clinpro XT, Profluorid, Fluor Protector S and untreated (control). Permeability tests were carried out: after acid conditioning, after treatment, and after abrasive/erosive challenges. The abrasive-erosive challenges were performed for 5 days (citric acid and in remineralizing saliva), as well as abrasion with toothpaste slurry (Colgate Total 12). Scanning electron microscopy (SEM) images were obtained of the dentin surfaces (5,000x) after the treatments, and after the erosive/abrasive challenges.

Results: Kruskal-Wallis and Dunn tests showed that all the varnishes promoted a decrease in dentin permeability directly after application, with Clinpro XT showing the highest percentage (69.52%) of dentin sealing (P= 0.0188). After the erosive/abrasive challenge, only PRG Barrier Coat varnish showed dentin sealing ability with reduced dentin permeability (42.16%) (P= 0.0014). However, none of the applied varnishes promoted a statistically significant difference in the percentage of dentin sealing, compared with the control group (P> 0.05). Clinpro XT showed a higher percentage of dentin sealing, while only PRG Barrier Coat showed reduced dentin permeability after the erosive/abrasive challenge.

Clinical significance: Varnish containing S-PRG filler has the efficacy needed to be used as a coating material to reduce dentin permeability in situations of erosive/abrasive challenges.

Purpose: To evaluate the improvement of selected mechanical properties of a resin-modified glass-ionomer cement (RMGIC) with a discontinuous short E glass fiber flowable resin composites (GFRRC) to be used in load-bearing areas of permanent teeth.

Methods: Experimental materials were prepared using two different weight proportions, 7 wt% (1.75% E glass fibers) and 25 wt% (6.25% E glass fibers) of a GFRRC into an RMGIC matrix. Flexural strength was evaluated in 0- and 24-hour hydration periods, and fracture toughness was assessed after 24 hours. The internal microstructure of fractured samples was evaluated using a scanning electron microscope.

Results: The addition of 25% of GFRRC was more effective in strengthening RMGIC than the introduction of only 7% GFRRC. Hydration periods did not show any significant statistical difference (P> 0.05). SEM micrographs of experimental materials' fractured surfaces revealed pull-out and fractured fibers; the presence of the matrix attached to fibers indicates great fiber-matrix adhesion. Within the limitations of the study, the results revealed that reinforcing RMGIC with discontinuous short E glass fiber flowable resin composites (GFRRC) improved significantly the flexural strength and modestly enhanced fracture toughness.

Clinical significance: The current study results are promising for the future of resin-modified glass-ionomer as a viable permanent restorative material in stress-bearing areas for permanent teeth after the reinforcement with short E glass fiber flowable resin composites as a source of discontinuous short glass fibers.

Purpose: To evaluate the smoothness provided by a one-step finishing and polishing system and its maintenance after hydrothermal aging and brushing of a nanofilled resin composite.

Methods: 96 samples of the nanofilled composite Filtek Z350 XT were fabricated, which, after initial average roughness (Ra) analysis, were randomly distributed into three groups, according to the selected finishing and polishing system. The multi-step systems Sof-Lex (aluminum oxide discs) and Jiffy (bullet-shaped abrasive rubbers), and the one-step system OneGloss (bullet-shaped abrasive rubber) were used. After finishing and polishing, a new Ra measurement was performed, and then half of the samples from each group were stored in artificial saliva for 12 months, while the other half underwent aging processes associating hydrothermal cycles (10,000 cycles at 5-55°C) followed by brushing (5,500 strokes), with a mid-abrasive (Crest Cavity Protection) dentifrice slurry, simulating a 12-month period in the oral cavity. Final Ra measurements were performed, and data were analyzed by generalized linear model and Tukey's test (α= 5%).

Results: There was interaction between finishing and polishing system and aging (P< 0.001). The one-step abrasive rubber point provided significantly higher Ra values compared to the multi-step systems, and with the discs there was higher smoothness than with the rubber point sequence. This result was maintained after 12 months in artificial saliva, but after hydrothermal cycles followed by brushing, one-step and multi-step abrasive rubber points no longer significantly differed from each other. Only for the one-step system, hydrothermal cycles followed by brushing significantly reduced Ra.

Clinical significance: Although hydrothermal cycles followed by brushing may have increased the smoothness of nanofilled composite finished and polished with the one-step system, only the multi-step system provided a surface within the roughness threshold to avoid biofilm retention.

Purpose: To assess the relief of dentin hypersensitivity of the new toothpaste with stabilized stannous fluoride (SnF₂) versus a marketed standard fluoride toothpaste as a negative control and a marketed anhydrous SnF₂ toothpaste as a positive control.

Methods: This was a single-centered, randomized, controlled, double blind, clinical trial. 96 participants with hypersensitivity were enrolled in this 4-week clinical study. Electrical stimulation and evaporative air tests were performed to evaluate the desensitization efficacy. Clinical assessments were made at baseline, and after 3 days, 1 week, 2 weeks and 4 weeks of twice-daily brushing. Additionally, the influence of Sn² ⁺ species on desensitization was evaluated using bovine dentin specimens treated with toothpaste.

Results: All 96 enrolled participants were randomized. 96 participants completed all evaluations. Participants had an average age (SD) of 47.0 (10.5) years; 45% of participants were female. Both SnF₂ toothpastes showed superior desensitization efficacy compared to the negative control toothpaste, the conventional sodium monofluorophosphate (SMFP) toothpaste, after a week. The new stabilized SnF₂ toothpaste demonstrated improved electrical stimulation benefits compared to the negative control toothpaste, with increases of 15.1% after 3 days, 34.2% after 1 week, 66.3% after 2 weeks, and 111.6% after 4 weeks. Additionally, it showed relative verbal evaluation scale (VES) benefits of 14.2% after 3 days, 37.6% after 1 week, 28.9% after 2 weeks, and 37.4% after 4 weeks. The stabilized SnF₂ toothpaste exhibited desensitization properties comparable to those of a commercial anhydrous SnF₂ toothpaste, which typically produces undesirable side effects in the mouth. Toothpastes containing 0.454 % SnF₂ exhibited perfect occlusion of dentin tubules.

Clinical significance: The stabilized 0.454% SnF₂ toothpaste exhibited significantly greater dentin hypersensitivity relief within only a week and comparable property to commercial anhydrous SnF₂ toothpaste.

Purpose: To compare toothpaste tablets containing 0.243% sodium fluoride and a conventional sodium fluoride dentifrice for gingivitis and plaque control over a 2-week period.

Methods: Forty adult participants were randomized into two groups: Toothpaste tablets (Colgate Anywhere Travel Toothpaste Tablets) and conventional dentifrice (Colgate Cavity Protection). A blinded examiner measured the gingival and plaque index at baseline and after 2 weeks. A questionnaire was distributed at the end to determine overall satisfaction of the product used. Statistical analyses were performed separately for the gingival index and plaque index scores. Comparisons of the two treatment groups with respect to baseline and 2-week gingival index and plaque index scores were performed using Mann-Whitney U-test. Within-treatment comparisons of the gingival index and plaque index scores obtained at the 2-week examinations versus baseline were performed using Wilcoxon test.

Results: Both groups had statistically significant improvements in plaque control at the 2-week visit (P< 0.05). There was no statistically significant difference between groups for gingival and plaque index at the 2-week visit (P> 0.05). Overall satisfaction for both products were positive while perception on "texture/foaminess" was more negative for toothpaste tablets (P= 0.001). The results showed that toothpaste tablets' short-term performance on gingivitis and plaque control was equivalent to conventional dentifrice while the " texture/foaminess" of toothpaste tablets was found to be less appealing.

Clinical significance: Toothpaste tablets are a relatively new form of toothpaste that can be a viable alternative to conventional dentifrice with the added benefit of an eco-friendly way of maintaining oral hygiene.

Purpose: To present the antibacterial effect of new generation boron-doped carbon quantum dots (B-CQD) and compare the antibacterial effect of silk sericin (SS), hydrolyzed silk peptide (HSP) and SS/HSP coated silver nanoparticle (AgNP) and B-CQDs on titanium alloy (Ti) surfaces.

Methods: SS and HSP were formed on the surface of the Ti alloy (Ti-SS/HSP). Different concentrations of citric acid and boric acid, B-CQDs and AgNP were attached to Ti-SS/HSP surfaces. To characterize all samples, Fourier Transform Infrared (FTIR), scanning electron microscopy (SEM) and energy dispersive X-ray (EDS) analyses were performed. Their antibacterial potential was analyzed against gram-positive Staphylococcus aureus (S. aureus) and gram-negative Pseudomonas aeruginosa (P. aeruginosa) with Mueller-Hinton Test. One-way ANOVA was used to assess any difference between groups. P< 0.05 was considered statistically significant.

Results: No antibacterial activity was detected for Ti and SS/HSP. Inhibition holes ranged from 11 mm to 25.7±3.2 mm and 11 mm to 26.3±0.6 mm in the S. aureus and P. aeruginosa cultures respectively, showing that AgNP was the molecule which had the least antibacterial effect regardless of type of bound silk protein on both bacteria, and B-CQD had antibacterial superiority against S. aureus and P. aeruginosa on Ti-SS surfaces.

Clinical significance: The application of boron-doped carbon quantum dots to titanium alloy surfaces is a new approach for the development of a powerful bactericidal method to prevent implant failures.

Purpose: To evaluate the effects of toothpaste tablets on the gloss and surface roughness of resin-based composite materials and determine the relationship between gloss and roughness.

Methods: Rectangular jigs were designed and printed. Wells (2 mm deep x 7 mm diameter) were filled with Filtek Supreme Ultra A2B, light-cured and polished. A small-area glossmeter was used for gloss (GU) measurements and a profilometer for roughness measurements (Ra) at baseline and after challenge with each toothpaste. An automated tooth-brushing machine was set at 120 strokes/minute for a total of 10,000 strokes to evaluate four test groups with 16 specimens in each group. NC: Brushing with distilled water; TABS: Colgate Anywhere Travel Tooth Tabs; CP: Colgate Cavity Protection Toothpaste and AW: Colgate Whitening Advanced Toothpaste. Kruskal-Wallis test was used to test the difference in gloss and surface roughness among the groups and Pearson correlation was used to compare the relationship between gloss and roughness.

Results: There was no statistically significant difference in gloss and roughness among the four groups at baseline. At post-brushing, there was a statistically significant difference among the groups (P< 0.001) with increased roughness and decreased gloss for CP and AW when compared to TABS. There was a statistically significant correlation between post-brushing roughness and post-brushing gloss (P< 0.001, rho: -0.815). Thus, the higher the surface roughness the lower the gloss.

Clinical significance: Toothpaste tablets retain better gloss and roughness of resin-based composite materials when compared to conventional toothpastes.