Aim To assess the effect of acid‐etching duration time on the compressive strength, microstructure and shear bond strength of All‐Bond Universal adhesive to MTA‐Angelus (AMTA), and Biodentine (BD). Methodology Forty‐eight cylindrical specimens (4 mm in diameter, 6 mm in height) of AMTA in four groups and 48 specimens of BD in four groups (n = 12) were prepared and stored for 72 h. The control groups were unetched whilst the three experimental groups were acid‐etched for 5, 10 and 15 s, respectively, followed by compressive strength testing. The effect of the various acid‐etching times on surface micromorphology was evaluated under a scanning electron microscope. Similar groups were bonded using All‐Bond Universal and Aelite Flo and shear bond strength was tested. Data were analysed using two‐way ANOVA and Tukey tests. Results 10‐s and 15‐s acid‐etching reduced the compressive strength of AMTA and BD (P < 0.001), while 5‐s etching did not (P ≤ 0.86). In all the groups, BD had greater compressive strength compared to AMTA. Contrary to BD, the three etched AMTA groups had significantly higher shear bond strength compared to the control group (P < 0.001), with no significant differences between them. The etched groups of AMTA had shear bond strengths comparable to all the BD groups. Scanning electron microscope observations indicated variable surface morphologies such as remnant crystals and cracking/eroding in all our groups of AMTA; though these differences were less prominent for BD. Conclusions Shortening the acid‐etching time to 5 s resulted in a beneficial effect in terms of resin bonding for AMTA while preventing the detrimental effect of 10‐s and 15‐s etching on the compressive strength of AMTA and BD. However, the three etching times had no effect on resin–BD bond.

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To systematically review the hyalinization of experimental tooth movement in humans and animals. Material and Methods: The electronic databases of MEDLINE, PubMed, Cochrane Library, Embase, Institute for Scientific Information, and Google Scholar were searched for performing a systematic review of the related literature published until 2019. Moreover, Endnote X9 software was utilized to manage electronic titles. The searches were fulfilled using keywords of "hyalinization," "orthodontic tooth movement" OR "OTM" AND "periodontal ligament" OR "PDL," "molecular pathways," AND "mechanical cell." Therefore, this systematic review was conducted based on the key consideration of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. Results: Forces ranged between 2.3 and 50 CN had been applied. According to the research design, incisors had been included in two experiments, whereas maxillary molars had been displaced by tipping forces in another rat examination. However, a majority of investigations had stated that hyalinization had firstly appeared within the first 24 hours. Moreover, the amount of prostaglandin-end peroxide synthase 2 (PTGS2) had been positively related to force term and size utilizing Western blotching. As PTGS2 had been included in the prostaglandin E2 (PGE2) metabolism, the up-regulation of PTGS2 gene expression could be connected with that of PGE2 emission. Conclusion: Gene expression in connection with force term and size and also the first signalling pathways were recognized utilizing protein-protein interactions (PPIs).

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background: the bond strength of bracket to the tooth substrate is a critical matter. The different surface treatments are introduced to achieve an appropriate bond strength. We aimed to investigate the shear bond strength(SBS) of metal brackets to amalgam surfaces with universal adhesive and compared the results with the enamel group. Material and methods: in this in-vitro study, eighty specimens of amalgam in four groups and sixty specimens of the enamel in three groups were prepared. In amalgam groups, the control group was sandblasted and treated with transbond Xt whilst the other three groups prepared in the following order, group 2 sandblasted and treated with All Bond Universal(ABU), group 3 using diamond bur and ABU, and group 4 using self-etch mode of ABU. In enamel groups, control group was acid-etched and using transbond XT as a primer; in other two groups, the ABU was used as a primer in etched and self-etched mode. The specimens thermocycled and prepared for the SBS test. SEM analysis and ARI index were performed. pvalue≤ was considered significantly. Results: SBS of enamel was significantly higher than amalgam. Within enamel groups, etched with ABU showed the highest SBS. In amalgam group, the highest SBS was related to surface treated with ABU only, and the lowest SBS was related to diamond bur group. Conclusion: The etched surface of enamel showed the appropriate bond strength to bracket, and in the amalgam group, using mechanical preparation can decrease the oxide layer and compromise amalgam SBS. Keywords: Dental amalgam, Enamel, shear strength, Adhesive