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Purpose: To compare the stress distribution through photoelasticity, microhardness and roughness of intact crowns of primary molars (CC) and the preformed crowns of stainless steel (SSC) and zirconia (ZC) used in dental restorations in pediatric dentistry., Methods: Six healthy primary molars were selected. For the photoelastic models, the teeth were fixed in photoelastic resin. A load of 100 N was applied, and the models were analyzed by transmission polariscope. The Tardy method was used to quantify the fringe order which calculates the maximum stress (T) value in each selected point. The teeth were prepared for cementation of the crowns. The photoelastic test was repeated for each experimental crown. Knoop microhardness was assessed on the buccal surfaces of the CCs, SSCs, and ZCs using a microhardness tester. Parameters were 50 gf for 5 seconds. Roughness was evaluated using a confocal 3-D laser scanning microscope/software at 216x magnification. Roughness average (Ra) values from each model (expressed in µm) were collected and group means were calculated. The stress distribution, microhardness, and roughness data were compared by using one-way ANOVA and the Tukey's test (α= 0.05)., Results: There was no difference in the stress distribution for the CCs, SSCs and ZCs. For the microhardness analysis, the ZCs obtained the highest values compared to the CCs and the SSCs (P< 0.001). The CCs were significantly higher than the SSCs (P= 0.027). There was no difference in roughness for the three models (P= 0.615). The SSCs and ZCs showed satisfactory mechanical behavior., Clinical Significance: The use of preformed crowns, especially those made of esthetic materials, is currently increasing in the field of pediatric dentistry. The knowledge of mechanical properties of stainless steel- and zirconia-prefabricated crowns provides scientific foundation for safe clinical application, especially in primary teeth., Competing Interests: The authors declared no conflict of interest. The present study was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brazil (CAPES) - Finance Code 001., (Copyright©American Journal of Dentistry.)

Purpose: To evaluate, in vitro, mechanical, chemical and antimicrobial properties of Embrace Wetbond bisphenol A (BPA)-free pit-and-fissure sealant., Methods: For the shear bond strength and microleakage tests, 135 healthy third molars were randomly divided into six groups, according to sealant [Fluroshield (FS) and Embrace Wetbond (EWB)] and contamination conditions (no contamination, contamination with saliva and contamination with water). In addition, EWB sealant was subjected to the following analyses: fluoride release using direct potentiometry, antimicrobial activity using the agar well diffusion method and quantification of BPA using gas chromatography and mass spectrometry. Data were analyzed statistically by ANOVA, Kruskal-Wallis test, Tukey's post-test, Dunn's post-test and Bonferroni post-test (α= 0.05)., Results: For shear bond strength, there was a statistically significant difference among the groups (P< 0.05), and FS presented the best results. Analysis of the microleakage results showed statistically significant differences among the groups (P< 0.05), except for EWB non-contaminated, contaminated with saliva, and contaminated with water (P> 0.05). FS without contamination presented the lowest microleakage of all groups (P< 0.05), followed by FS contaminated with saliva, and three groups in which EWB was used under different conditions. FS contaminated with water presented the highest microleakage (P< 0.05). EWB showed higher fluoride release in water and artificial saliva on the first day (P< 0.05). EWB had greater antimicrobial activity than FS. BPA and Bis-GMA were not detected in EWB. When used according to the manufacturer's instructions (i.e., under conditions of moisture contamination), EWB showed high fluoride release, high antimicrobial activity, no release of BPA or Bis-GMA and shear bond strength close to the minimum acceptable value. However, this sealant presented statistically significantly more microleakage than the other tested materials., Clinical Significance: Knowing the adverse effects of BPA in the body, the present study has clinical relevance since it demonstrates some mechanical, chemical and antimicrobial properties of a BPA-free pit-and-fissure sealant., Competing Interests: The authors declared no conflicts of interest. This study was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brazil (CAPES) - Finance Code 001., (Copyright©American Journal of Dentistry.)

Purpose: To evaluate the effect of ultrasonic, sonic and rotating-oscillating powered toothbrushing systems on surface roughness and wear of white spot lesions and sound enamel., Methods: 40 tooth segments obtained from third molar crowns had the enamel surface divided into thirds, one of which was not subjected to toothbrushing. In the other two thirds, sound enamel and enamel with artificially induced white spot lesions were randomly assigned to four groups (n=10) : UT: ultrasonic toothbrush (Emmi-dental); ST1: sonic toothbrush (Colgate ProClinical Omron); ST2: sonic toothbrush (Sonicare Philips); and ROT: rotating-oscillating toothbrush (control) (Oral-B Professional Care Triumph 5000 with SmartGuide). The specimens were analyzed by confocal laser microscopy for surface roughness and wear. Data were analyzed statistically by paired t-tests, Kruskal-Wallis, two-way ANOVA and Tukey's post-test (α= 0.05)., Results: The different powered toothbrushing systems did not cause a significant increase in the surface roughness of sound enamel (P> 0.05). In the ROT group, the roughness of white spot lesion surface increased significantly after toothbrushing and differed from the UT group (P< 0.05). In the ROT group, brushing promoted a significantly greater wear of white spot lesion compared with sound enamel, and this group differed significantly from the ST1 group (P< 0.05). None of the powered toothbrushing systems (ultrasonic, sonic and rotating-oscillating) caused significant alterations on sound dental enamel. However, conventional rotating-oscillating toothbrushing on enamel with white spot lesion increased surface roughness and wear., Clinical Significance: None of the powered toothbrushing systems (ultrasonic, sonic and rotating-oscillating) tested caused significant alterations on sound dental enamel. However, conventional rotating-oscillating toothbrushing on enamel with white spot lesion increased surface roughness and wear., Competing Interests: The authors have no conflicts of interest., (Copyright©American Journal of Dentistry.)