Efficiency evaluation of maxillary molar distalization using Invisalign based on palatal rugae registration.

INTRODUCTION: This study aimed to compare the predicted maxillary molar distalization with the achieved clinical outcome using the palatal rugae area for registration and superimposition of digital models. Understanding Invisalign efficiency may assist clinicians in predicting changes, thus applying specific measures to minimize the chance of midcourse correction later. METHODS: The study sample included 38 patients with a mean age of 25.4 years, eligible for Invisalign treatment and requiring distalization of maxillary molars. Two digital models were acquired using iTero intraoral scanner (Align Technology, Santa Clara, Calif) before treatment and after maxillary first and second molar distalization. The 2 digital models were superimposed using the palatal rugae area for registration. The predicted tooth movement compared to the achieved values. One hundred forty-two maxillary molars (71 first molar and 71 second molar) were measured for distal movement, and 228 maxillary anterior teeth were evaluated for anterior anchorage loss. RESULTS: The predicted distal movement of the maxillary first molar (P <0.0001) and maxillary second molar (P <0.0001) differed significantly from the actual values. There was a statistically significant correlation between the amount of distal molar movement and the amount of anchorage loss (r = 0.3900, P <0.008) for the central incisor, and (r = 0.3595, P <0.013) for the lateral incisor. CONCLUSIONS: Invisalign can be used successfully for adult patients requiring maxillary molar distalization when a mean distalization movement of 2.6 mm was prescribed. Clinicians should be aware of the countereffect if maxillary molars are planned to move distally, especially if the patient presented initially with a large overjet, so the need to prescribe overcorrection or the use of auxiliaries can be addressed earlier.

From Two-, One-, to Zero-Dimensional Vacancies: A Densification Pattern for a Typcial Transition-Metal Dichalcogenide of TiSe2.

In the areas of condensed matter physics, geoscience, material science, and inorganic chemistry, how the crystal structures evolve under an external field such as high-pressure is a fundamental question. By taking TiSe2 as the case, we investigate the phase transformations of the layered transition-metal dichalcogenides (TMDs) under high-pressure. The ambient 6-fold P-3m1 TiSe2 undergoes a transformation into the monoclinic 8-fold coordinated C2/m phase at 15 GPa and then into the hexagonal 9-fold Fe2P-type structure at 34 GPa. The above phase transitions can be unitedly described as the evolution of the vacancies: from a layered structure with two-dimensional (2D) vacancies to the structure with one-dimensional (1D) and zero-dimensional (0D) vacancies. The proposed densification model of TiSe2 reveals the processes how the symmetry breaking phase of spatial chemical bonding restores the symmetry under the isotropic external pressure.

The recurrence of dense face-centered cubic cesium.

At ambient conditions, alkali metal cesium (Cs) owns a body-centered cubic phase, and this phase will transform to a face-centered cubic (fcc) phase at a pressure of 2.3 GPa. Under stronger compression, Cs will transform to oC84, tI4, oC16, and double hexagonal close-packed (dhcp) phases in sequence. Here, using first-principles structure searching prediction and total-energy calculation, we report that the Cs will re-transform to the fcc phase as the post-dhcp phase above 180 GPa. The transition state calculations suggest that the phase transition takes place by overcoming an energy barrier (144 meV/atom at 200 GPa) and finishes within a volume collapse of 0.3%. The electronic states at Fermi level are derived mainly from d electrons and there is a large overlap between inner core electrons, making the high-pressure fcc Cs distinguished from the first one at low pressure. The same phase transition also occurs in potassium and rubidium but with higher pressures.

Maternal low protein exposure alters glucose tolerance and intestinal nutrient-responsive receptors and transporters expression of rat offspring.

AIMS: Maternal protein malnutrition during perinatal period has long-term consequences on the offspring's metabolic phenotype. Here we determined the effects of maternal protein-restricted (PR) diet on offspring's metabolism in 3- and 12-week-old. MAIN METHODS: Sprague-Dawley rats were fed with standard chow diet or PR diet during pregnancy and lactation. Food intake and body weight of offspring were measured weekly. The oral glucose tolerance tests were underwent, the pancreases were collected for histochemical staining, and the duodenum, jejunum and ileum were collected for gene and protein expression analysis in 3- and 12-week-old offspring. KEY FINDINGS: PR offspring had significant lower body weight and persisted till 12-week-old. From 3- to 12-week-old, PR offspring presented considerably impaired glucose tolerance, while no marked change was shown in control rats. Additionally, the average islet size of PR offspring decreased significantly in 12-week-old. The mRNA and protein expression of nutrient-responsive receptors and transporters T1R3, SGLT1 and GLUT2 increased significantly in the intestine of 3-week-old PR offspring. And from 3- and 12-week-old, the increase tendency of expression subdued. SIGNIFICANCE: These results suggest that maternal PR diet during critical developmental windows influences offspring metabolism, which may be subdued partially, but not be reversed completely by chow diet after weaning.

The purinergic mechanism of the central nucleus of amygdala is involved in the modulation of salt intake in sodium-depleted rats.

The central nucleus of the amygdala (CeA) is a critical region in regulating sodium intake, and interestingly, purinergic receptors reportedly related to fluid balance, are also expressed in CeA. In this study, we investigated whether the purinergic mechanisms of CeA were involved in regulating sodium intake. Male Sprague-Dawley rats had cannulas implanted bilaterally into the CeA and were sodium depleted with furosemide (FURO 20 mg/kg) plus 24 h-sodium deficient food fed. Bilateral injections of the P2X purinergic agonist, α,ß-methyleneadenosine 5'-triphosphate (α,ß-methylene ATP 1.0, 2.0, 4.0 nmol, respectively) into the CeA region induced dose-related reductions in sodium intake without affecting water intake. Injection of P2X purinergic antagonist, pyridoxalphosphate-6-azophenyl-2',4'-disulfonic acid (PPADS 4.0 nmol/0.5 µl) into the CeA region did not alter sodium and water intake, however, prior injection of PPADS into the CeA area abolished the inhibitory effects on sodium intake by α,ß-methylene ATP. Interestingly, prior injection of γ-aminobutyric acid type A (GABAA) receptor antagonist, bicuculline (4.0 nmol/0.5 µl) into the CeA region partially reversed the deficit of sodium intake induced by α,ß-methylene ATP. These results suggest that purinergic receptors in the CeA are involved in the control of sodium intake in the sodium-depleted rats and this negative modulation may be, at least partly, mediated by the GABAA receptor.

Investigation of a Novel PLGA/CaP Scaffold in the Healing of Tooth Extraction Sockets to Alveolar Bone Preservation in Humans.

BACKGROUND: It is expected that 40% to 60% of initial alveolar bone volume will be lost up to 6 months after tooth extraction. OsteoScaf(TM) (TRT, Toronto, ON, Canada) (poly (DL-lactide-co-glycololide/calcium phosphate [PLGA/CaP] scaffold) is a novel bone substitute material and represents a promising alternative for maintaining alveolar bone integrity in this clinical scenario. PURPOSE: Here it was hypothesized that OsteoScaf would reduce alveolar bone lost after tooth extraction in patient, acting as a clot-retention device. MATERIAL AND METHODS: A total of 10 patients (32 sockets) were included in the study, of which 16 sockets were grafted with OsteoScaf and 16 were used as control (coagulum alone). Cone beam computed tomography (CBCT) was performed both immediately following extraction and also at 120 days postoperatively, at which time biopsy samples were also harvested for histological analyses. RESULTS: Quantitative analysis of CBCT showed less bone resorption in the OsteoScaf groups, being 10.5% to 14.4% less bone lost in the center of the socket, 15.4% in the buccal region, and 12.6% in the palatal. Qualitative histological analysis showed new bone tissue in direct apposition to the scaffold - demonstrating its osteoconductive nature. CONCLUSION: OsteoScaf diminished the expected bone lost during the postextraction remodeling of the alveolar bone ridge at 120 days postextraction.

Bone regeneration by nanohydroxyapatite/chitosan/poly(lactide-co-glycolide) scaffolds seeded with human umbilical cord mesenchymal stem cells in the calvarial defects of the nude mice.

In the preliminary study, we have found an excellent osteogenic property of nanohydroxyapatite/chitosan/poly(lactide-co-glycolide) (nHA/CS/PLGA) scaffolds seeded with human umbilical cord mesenchymal stem cells (hUCMSCs) in vitro and subcutaneously in the nude mice. The aim of this study was to further evaluate the osteogenic capacity of nHA/CS/PLGA scaffolds seeded with hUCMSCs in the calvarial defects of the nude mice. Totally 108 nude mice were included and divided into 6 groups: PLGA scaffolds + hUCMSCs; nHA/PLGA scaffolds + hUCMSCs; CS/PLGA scaffolds + hUCMSCs; nHA/CS/PLGA scaffolds + hUCMSCs; nHA/CS/PLGA scaffolds without seeding; the control group (no scaffolds) (n = 18). The scaffolds were implanted into the calvarial defects of nude mice. The amount of new bones was evaluated by fluorescence labeling, H&E staining, and Van Gieson staining at 4 and 8 weeks, respectively. The results demonstrated that the amount of new bones was significantly increased in the group of nHA/CS/PLGA scaffolds seeded with hUCMSCs (p < 0.01). On the basis of previous studies in vitro and in subcutaneous implantation of the nude mice, the results revealed that the nHA and CS also enhanced the bone regeneration by nHA/CS/PLGA scaffolds seeded with hUCMSCs in the calvarial defects of the nude mice at early stage.

Preparation and characterization of a highly macroporous biodegradable composite tissue engineering scaffold.

A unique composite scaffold for bone-tissue engineering applications has been prepared by combining biodegradable poly(lactide-co-glycolide) (PLGA) with bioresorbable calcium phosphate (CaP) cement particles through the process of particle fusion and phase separation/particle leaching. The scaffold is characterized by a highly interconnected macroporosity, with macropores of 0.8-1.8 mm and porosities ranging from 81% to 91%, and improved mechanical properties with respect to the polymer alone, producing excellent dimensional stability. The scaffold properties were controlled by adjusting the processing parameters, including PLGA molar mass and concentration, CaP/PLGA ratio, and porogen size. The differences in mechanical properties between dry, wet/room temperature, and wet/37 degrees C testing conditions, of which the latter are more relevant for materials to be employed in a biological milieu, were investigated. Thus, a scaffold made from PLGA IV 1.13, PLGA concentration 12.5%, and CaP/PLGA ratio 2:1 exhibited significantly different compressive strengths of 0.16 MPa and 0.04 MPa when tested under dry and wet/37 degrees C conditions, respectively. .

Periodontal regeneration using a bilayered PLGA/calcium phosphate construct.

The regeneration of tissues affected by periodontal disease is a complex process; it encompasses the formation of bone, cementum and periodontal ligament. We developed a semi-rigid PLGA (polylactide-co-glycolide acid)/CaP (calcium phosphate) bilayered biomaterial construct to promote periodontal regeneration, which has a continuous outer barrier membrane and an inner topographically complex component. Our experimental model compared periodontal prophylaxis alone with prophylaxis and biomaterial implantation in the treatment of class II furcation defects in dogs. Clinical evaluation, micro-computed tomography, histology and backscattered electron imaging were used for data analysis. Healing occurred uneventfully and bone volumetric values, trabecular number and trabecular thickness were all significantly greater in the treated group; while trabecular separation was significantly greater in the control group. New cementum, bone, and periodontal ligament with Sharpey fibre insertions were only seen in the treated group. Although periodontal regeneration has been reported elsewhere, the advantages of employing our bilayered PLGA + CaP construct are twofold: 1)it did not collapse into the defect; and, 2) its inner side was able to retain the blood clot throughout the buccal defect. The result was greater periodontal regeneration than has previously been reported with traditional flexible membranes.