Effect of Premolar Extraction on the Upper Airway in Adult and Adolescent Orthodontic Patients: a Meta-analysis.

OBJECTIVE: To analyse the effects of premolar extraction on the upper airway in adult and adolescent orthodontic patients using CBCT. METHODS: The Embase, Web of Science, Cochrane Library and Medline (via PubMed) databases were searched with no language restrictions. Longitudinal studies in which CBCT was applied to assess the effects of tooth extraction on the upper airway were included in the analysis. Two authors performed the study selection, methodological quality assessment, data extraction and data synthesis independently. RESULTS: A total of 12 studies were included, six of which were eligible for quantitative synthesis. In the adult group, the nasopharynx and oropharynx volume showed no significant change, and the minimum cross-sectional area of the upper airway demonstrated a non-significant decrease compared to the non-extraction group. In the adolescent group, the nasopharynx volume, oropharynx volume and minimum cross-sectional area of the upper airway increased in a non-significant manner. CONCLUSION: The currently available evidence indicates that tooth extraction does not increase the risk of airway collapse in adult and adolescent patients. The present findings should be interpreted with caution and evaluated in further high-quality studies.

Theranostic liposomes loaded with quantum dots and apomorphine for brain targeting and bioimaging.

Quantum dots (QDs) and apomorphine were incorporated into liposomes to eliminate uptake by the liver and enhance brain targeting. We describe the preparation, physicochemical characterization, in vivo bioimaging, and brain endothelial cell uptake of the theranostic liposomes. QDs and the drug were mainly located in the bilayer membrane and inner core of the liposomes, respectively. Spherical vesicles with a mean diameter of ~140 nm were formed. QDs were completely encapsulated by the vesicles. Nearly 80% encapsulation percentage was achieved for apomorphine. A greater fluorescence intensity was observed in mouse brains treated with liposomes compared to free QDs. This result was further confirmed by ex vivo imaging of the organs. QD uptake by the heart and liver was reduced by liposomal incorporation. Apomorphine accumulation in the brain increased by 2.4-fold after this incorporation. According to a hyperspectral imaging analysis, multifunctional liposomes but not the aqueous solution carried QDs into the brain. Liposomes were observed to have been efficiently endocytosed into bEND3 cells. The mechanisms involved in the cellular uptake were clathrin- and caveola-mediated endocytosis, which were energy-dependent. To the best of our knowledge, our group is the first to develop liposomes with a QD-drug hybrid for the aim of imaging and treating brain disorders.

[Photoelastic analysis of movement tendency of lower teeth using multiloop edgewise archwire with vertical elastics in anterior teeth area].

OBJECTIVE: To investigate the movement tendency of lower teeth using multiloop edgewise archwire (MEAW) with vertical elastics in anterior teeth area by three-dimensions photoelastic analysis. METHODS: The photoelastical model of full teeth as human body on physical parameter and dimension was established and loaded by MEAW with vertical elastics in anterior teeth area similar with clinic. Every freezing model-tooth was bladed by anteroposterior axes and vertical axes, the stress of every point of alveolar bone was calculated by three-dimensions shear-equation method. The stress distribution regularity of per-tooth was analyzed to describe their move tendency. RESULTS: The lower second molar was intrused and rotated to distal and inclined as negative torque. The lower first molar moved and rotated to distal, the mesial rotate to buccally and the distal rotate to lingually. The lower second pre-molar was extruded and inclined as crown to mesial and root to distal, inclined as negative torque. The lower canine was intrused slightly and inclined as positive torque. The lower lateral incisor was extruded and moved and inclined as positive torque. CONCLUSION: Using MEAW with several "L" loop can control the movement of every tooth in three dimension.