Search

Physical and mechanical properties of high-viscosity bulk-fill resin composites submitted to additional polymerization for semi-direct use were evaluated. Filtek Z350 XT, Aura Bulk Fill, Beautifil Bulk Restorative, Filtek One Bulk Fill Restorative, and Tetric N-Ceram Bulk Fill were submitted to additional polymerization to evaluate sorption, solubility, surface microhardness, surface roughness before and after simulated brushing, color stability after coffee staining, flexural strength, elastic modulus, and modulus of resilience. Filtek Z350 XT and Filtek One Bulk Fill Restorative showed higher sorption values, while Aura Bulk Fill showed higher solubility (p<0.0001). Microhardness values were significantly higher for Filtek Z350 XT (p<0.0001). Roughness increased after wear for all resins (p<0.05). All resins exhibited staining, with significantly higher ΔEab, ΔE00, and ΔWID values observed for Beautifil Bulk Restorative (p<0.0001). Flexural strength values were higher for Filtek Z350 XT and Filtek One Bulk Fill Restorative in comparison with the others (p<0.0001). Filtek One Bulk-Fill had higher elastic modulus and modulus of resilience values (p<0.0001). Physical and mechanical properties varied according to the composition. None of the bulk-fill resins showed surface microhardness and roughness properties after brushing similar to or superior to those of the conventional type. Color stability after staining depended on resin composition, with Beautifil Bulk Restorative showing more intense staining., (©Operative Dentistry, 2025.)

There is a constant search for bleaching treatments that can offer greater safety with fewer adverse effects, especially in the techniques performed in the office, which usually employ hydrogen peroxide in high concentrations (35% to 40%) that are not recommended by some international control agencies. This in vitro study evaluated the color change after tooth bleaching with the use of ozone and a 10% ozonized carbamide peroxide bleaching treatment for in-office use. Thirty molars were allocated (n = 10): three applications of ozone (1 hour every 3 days); three applications of 10% ozonized carbamide peroxide (1 hour every 3 days); 10% carbamide peroxide agent (8 hours a day for 7 days). The teeth were mounted on a plaster model to simulate the dental arch, and trays made of silicone were used for the application of the bleaching agents and to allow ozone to enter through. The ozone concentration used was 60 μg/mL, with an oxygen flow of 0.25 L/min. The values of color change showed no significant differences among treatments. The variations in the parameters over time, as well as the values of ΔE ab , ΔE 00 , and WI D , showed that there was no significant difference among the three treatments. The use of ozone and 10% ozonized carbamide peroxide for in-office use was effective for tooth bleaching with clinically perceptible and acceptable color alterations. The study was approved on September 10, 2019 by the São Leopoldo Mandic Ethics Research Committee (CAAE No. 17711719.4.0000.5374)., Competing Interests: None

Background: The study aimed to assess the influence of different implant insertion angles and depths on the stresses produced on the surface of peri-implant bone tissue under axial and oblique loading., Material and Methods: The entire study followed the recommendations of the Checklist for Reporting In-vitro Studies (CRIS). The implant was placed in the region of element 36, according to the following models: M1 (0 mm / 0°); M2 (0 mm / 17°); M3 (0 mm / 30°); M4 (2 mm / 0°); M5 (2 mm / 17°); M6 (2 mm / 30°). The models were subjected to loading, with intensity of 100 N. The stress assessment followed the Mohr-Coulomb criterion and qualitative and quantitative analyses were performed., Results: Angled implants and installed below the bone crest produced the highest stresses on the cortical bone, and the axial load presented the highest stress peaks on the buccal side of implants perpendicular to the bone crest. Regardless of the type of load (axial or oblique), inclined implants presented the highest stress peaks on the lingual side of the cortical bone., Conclusions: Implants installed perpendicular to and with a prosthetic platform at bone crest height provided the lowest stresses to peri-implant bone tissue under both axial and oblique loading. Key words: Finite element analysis, dental implants, axial loading, biomechanical phenomena., Competing Interests: Conflicts of interest None., (Copyright: © 2021 Medicina Oral S.L.)

Purpose: To measure the microgap between dental implants and custom abutments fabricated using different computer-aided design/computer-aided manufacture (CAD/CAM) methods before and after mechanical cycling., Materials and Methods: CAD software (Dental System, 3Shape) was used to design a custom abutment for a single-unit, screw-retained crown compatible with a 4.1-mm external hexagon dental implant. The resulting stereolithography file was sent for manufacturing using four CAD/CAM methods (n = 40): milling and sintering of zirconium dioxide (ZO group), cobalt-chromium (Co-Cr) sintered via selective laser melting (SLM group), fully sintered machined Co-Cr alloy (MM group), and machined and sintered agglutinated Co-Cr alloy powder (AM group). Prefabricated titanium abutments (TI group) were used as controls. Each abutment was placed on a dental implant measuring 4.1× 11 mm (SA411, SIN) inserted into an aluminum block. Measurements were taken using scanning electron microscopy (SEM) (×4,000) on four regions of the implant-abutment interface (IAI) and at a relative distance of 90 degrees from each other. The specimens were mechanically aged (1 million cycles, 2 Hz, 100 N, 37°C) and the IAI width was measured again using the same approach. Data were analyzed using two-way analysis of variance, followed by the Tukey test., Results: After mechanical cycling, the best adaptation results were obtained from the TI (2.29 ± 1.13 μm), AM (3.58 ± 1.80 μm), and MM (1.89 ± 0.98 μm) groups. A significantly worse adaptation outcome was observed for the SLM (18.40 ± 20.78 μm) and ZO (10.42 ± 0.80 μm) groups. Mechanical cycling had a marked effect only on the AM specimens, which significantly increased the microgap at the IAI., Conclusion: Custom abutments fabricated using fully sintered machined Co-Cr alloy and machined and sintered agglutinated Co-Cr alloy powder demonstrated the best adaptation results at the IAI, similar to those obtained with commercial prefabricated titanium abutments after mechanical cycling. The adaptation of custom abutments made by means of SLM or milling and sintering of zirconium dioxide were worse both before and after mechanical cycling.

Objective: This study evaluated the effectiveness of toothbrushing with whitening toothpaste in altering the shade of stained human enamel., Materials and Methods: Thirty fragments of human enamel, stained with chlorhexidine/black tea underwent 1000 and 5000 brushing cycles (BC) with ( n = 10): PLS (Gel Dental Day, Bitufo), Close Up White Now, Unilever (COVB) and regular (Gel Dental Night, Bitufo) toothpaste. Images were taken before staining (baseline), after staining (STN) and following 1000 and 5000 BC and were analyzed using the CIELAB parameters (ΔE, Δb and ΔL)., Statistical Analysis Used: Data were submitted to two-way ANOVA (α = 0.05)., Results: ΔE was higher from STN to baseline; 1000 BC to STN and 5000 BC to STN ( P < 0.001). Significant differences in Δb values were found from 1000 BC to STN and 5000 BC to STN. For COVB, greater ΔL was observed from 1000 BC to STN, what differed statistically from the regular toothpaste ( P < 0.05). There was no difference between toothpaste when ΔL was calculated from 5000 CB to STN., Conclusions: Toothpaste containing COVB or PLS in association with 5000 BCs showed similar effectiveness in changing enamel shade; but after the first 1000 toothbrushing cycles, the use of COVB toothpaste promoted higher lightness in stained enamel., Competing Interests: There are no conflicts of interest.

Objectives: The aim of this study was to evaluate the capacity of two rotatory instruments (controlled speed electric motor [CSEM] - 300 rpm; conventional slow handpiece [CSHP] - 18,000 rpm) to remove sound and demineralized dentin, by examining prepared cavity walls using the scanning electron microscopy (SEM) and assessing loss of mass., Materials and Methods: A total of 40 blocks of human occlusal dentin, measuring 5 mm × 5 mm × 4 mm (L × W × H), were divided into two groups according to the substrate type in which the cavity preparation was performed: D - demineralized dentin; and S - sound dentin (control group). The groups were subdivided according to the rotatory instrument used for cavity preparation (n = 10): CSEM (300 rpm); and CSHP (18,000 rpm). In half of the dentin blocks, caries lesion induction was performed for 6 weeks. The preparation of the cavities was performed on a standardizing machine, using a cylindrical tungsten carbide burr. Before and after the preparation, specimens were dehydrated in an incubator at 60°C for 30 min. The initial and final mass (in mg) of each dentin block was measured 3 times using the digital precision balance to obtain the mean weight Following cavity preparation, all specimens were hemisected and SEM was used to blindly assess each half so that the lateral walls of the prepared cavity were measured in μm, accepting the average of two measurements as the total depth of the preparation. Non-parametric Mann-Whitney analysis was performed with a 5% of significance level., Results: Regarding the weight difference (mg), no significance was detected between the groups. Regarding depth (μm), a significant difference was found between the groups, so that the CSRM showed lower cavity depth when compared with CSHP, both in sound and demineralized dentin., Conclusions: Controlled speed rotatory instruments were found to be more conservative in removing both sound and demineralized dentin, in terms of preparation and depth.