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Objectives: This retrospective CBCT study aimed to evaluate the palatal anatomical characteristics using the third palatal ruga as a reliable clinical reference for miniscrew placement., Methods: Thirty-six subjects (mean age17.1 y.o. ± 4.1) were randomly selected and their records (CBCT volume and maxillary digital models) were included.BlueSkyPlan CBCT software viewer (BluSkyBio, V4.7) was used to measure the following outcomes at the level of third palatal ruga, 2 mm anteriorly and 2 mm posteriorly: total bone depth, cortical bone thickness, and mucosa thickness. The outcomes were evaluated on lines perpendicular to the palatal mucosa laying on different sagittal planes: the mid-palatal plane, 2 and 4 mm paramedian planes., Results: The maximum mean amount of bone depth was registered 2 mm posteriorly to the third ruga and 4 mm paramedian (9.7 mm). No significant difference was observed between the third ruga insertion site and its corresponding 2 mm posterior site. Cortical bone of palatal vault did not change significantly in anteroposterior direction for all the considered sites. Significant differences were found comparing cortical bone at the suture level with cortical bone 2-mm and 4-mm paramedian at all anteroposterior levels. Palatal mucosa increases its thickness in paramedian insertion sites, and it decreases in posterior insertion sites., Conclusions: Both third palatal ruga and 2 mm posteriorly to third ruga (4 mm paramedian) could be the optimal insertion site for palatal miniscrew placement, depending on individual anatomic conditions. The thickness of the cortical palatal bone showed, at 4 mm paramedian, optimal characteristics for miniscrew primary stability. Palatal mucosa thickness values suggest miniscrew neck extension of 2.0-2.5 mm for optimal mucosa adaptation., (© The Author(s) 2022. Published by Oxford University Press on behalf of the European Orthodontic Society. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Objective: This study aims to investigate the diagnostic concordance between skeletal cephalometrics and soft-tissue cephalometrics in identifying facial lower third characteristics., Materials and Methods: We compared a skeletal cephalometric analysis (SCA) to a soft-tissue analysis performed on cephalometric radiographs (rSTCA) and to one performed on profile photograph (pSTCA). Ninety-six pre-treatment digital lateral cephalometric radiographs and 96 digital profile photographs were randomly selected for this study (patients' mean age: 18.33, SD: 3.38, age range: 14-29). Inclusion criteria were as follows: no skeletal asymmetry, well-aligned upper and lower dental arches, no history of orthodontic treatment, prosthodontic treatment, facial surgery and trauma, patient's age between 14 and 30 years, high-resolution images, exams taken with natural head position. Kruskas-Wallis and post hoc pairwise comparisons tests were used to find differences among the considered cephalometric methods. The diagnostic performance of the three methods was also assessed using the receiver-operating characteristic (ROC) curve analysis., Results: Significant differences were found between SCA and rSTCA and between SCA and pSTCA in defining sagittal and vertical facial lower third characteristics (P < 0.05). No differences were found between rSTCA and pSTCA (P > 0.05) for the same facial characteristics. For each parameters investigated, pSTCA showed an area under the curve much closer to the perfect value of 1.00., Conclusion: Poor diagnostic concordance was found between SCA and rSTCA and between SCA and pSTCA. pSTCA is a reliable method for evaluating the soft-tissue profile characteristics compared to that performed on cephalograms., (© The Author 2016. Published by Oxford University Press on behalf of The European Orthodontic Society. All rights reserved. For permissions, please email: journals.permissions@oup.com)

The aim of this study was to investigate the mechanical properties of superelastic and thermal nickel-titanium (NiTi) archwires for correct selection of orthodontic wires. Seven different NiTi wires of two different sizes (0.014 and 0.016 inches), commonly used during the alignment phase, were tested. A three-point bending test was carried out to evaluate the load-deflection characteristics. The archwires were subjected to bending at a constant temperature of 37°C and deflections of 2 and 4 mm. Analysis of variance showed that thermal NiTi wires exerted significantly lower working forces than superelastic wires of the same size in all experimental tests (P < 0.05). Wire size had a significant effect on the forces produced: with an increase in archwire dimension, the released strength increased for both thermal and superelastic wires. Superelastic wires showed, at a deflection of 2 mm, narrow and steep hysteresis curves in comparison with the corresponding thermal wires, which presented a wide interval between loading and unloading forces. During unloading at 4 mm of deflection, all wires showed curves with a wider plateau when compared with 2 mm deflection. Such a difference for the superelastic wires was caused by the martensite stress induced at higher deformation levels. A comprehensive understanding of mechanical characteristics of orthodontic wires is essential and selection should be undertaken in accordance with the behaviour of the different wires. It is also necessary to take into account the biomechanics used. In low-friction mechanics, thermal NiTi wires are to be preferred to superelastic wires, during the alignment phase due to their lower working forces. In conventional straightwire mechanics, a low force archwire would be unable to overcome the resistance to sliding.

The aim of this in vitro study was to evaluate the frictional forces between bracket and archwire that included three passive self-ligating brackets (Damon SL2 SDS). The brackets were individually bonded to a brass mount using a preformed 0.021 x 0.025 inch stainless steel wire jig in order to exclude adverse tipping or torsion. The central bracket was positioned 1 mm higher than the others, in order that the three brackets were vertically unaligned. Thirty-six similar set-ups including in total 108 brackets were investigated using the same wire: copper (nickel-titanium) 0.014 inches. A testing machine was designed and constructed to measure the frictional forces between the wire and the three-bracket set-up. Twelve set-ups were tested to measure kinetic frictional forces between the wire and unaligned passive self-ligating brackets used in the closed position. The frictional properties of two sets of 12 three-bracket set-ups (control) were tested and measured with an open slide and conventional ligation. A stainless steel ligature wire was used in the former, while elastomeric modules were employed in the latter. One-way analysis of variance showed a significant effect of ligation mode on the frictional properties of the three-bracket set-ups (P < 0.001). Post hoc pairwise comparison showed that the frictional forces arising from passive self-ligation were significantly lower (P < 0.01) than those resulting from elastic ligation. The same result was achieved when comparing self-ligation and metallic ligation (P < 0.01). No significant difference was found when comparing elastic and metallic ligation.