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Objectives: The current study aims to explore the stress distribution along the roots of palatally positioned maxillary canines during orthodontic movement using a novel computational spring model. Methods: An experimental analysis based on the spring-model was utilized to calculate Orthodontic Tooth Movement (OTM) and the resulting stresses. Two sets of experiments were conducted: the first set compared stresses on a canine resulting from a single force and a force-couple, while the second set simulated canines' traction during instantaneous movement with varying original tooth angulations using different off-the-shelf orthodontic coils. In total, 130 simulations were performed. Results: The model provided estimated stress distribution throughout the OTM with the expected movements, producing consistent outcomes with prior findings. In the first set of experiments, the force couple exhibited an average stress of 43 KPa, while a single force yielded 51 KPa on average. The maximum stress observed was 63 KPa for the force couple and 130 KPa for a single force. Note that the stress distribution attributed to the force couple was alleviated in comparison to the stress distribution caused by a single force. Force couples generated higher average stress. In the second experiment, the application of an occlusally-directed inclined force led to reduced stress levels overall. For instance, when a 200 g distal force was exerted on the canine, it generated an average stress of 20 KPa, whereas applying a force of the same magnitude in an occlusal-distal direction resulted in a lower average stress of 15.5 KPa. Conclusions: Lower average stress levels when using a force couple indicate that larger loads might be safely applied for rotational movements. Given that areas under maximal stress are prone to damage, orthodontic treatment planning should carefully consider stress distribution to minimize potential harm in these high-stress zones. The results also suggest that force couples enable the use of stronger forces than a single force. Additionally, it is advisable to extrude the tooth initially before starting any horizontal movement towards the target position. Clinical significance: Given that orthodontic treatment often relies on virtual planning, incorporating a variety of methods to evaluate stress distribution within the treatment strategy could offer numerous benefits. Such an approach holds the potential to improve both the efficiency and safety of orthodontic treatments, especially in complex cases that require the application of high forces.

Purpose: The stresses and deformations in the periodontal ligament (PDL) under the realistic kinetic loading of the jaw system, i.e., chewing, are difficult to be determined numerically as the mechanical properties of the PDL is variably present in different finite element (FE) models. This study was aimed to conduct a dynamic finite element (FE) simulation to investigate the role of the PDL (PDL) material models in the induced stresses and deformations using a simplified patient-specific FE model of a human jaw system. Methods: To do that, a realistic kinetic loading of chewing was applied to the incisor point, contralateral, and ipsilateral condyles, through the experimentally proven trajectory approach. Three different material models, including the elasto-plastic, hyperelastic, and viscoelastic, were assigned to the PDL, and the resulted stresses of the tooth FE model were computed and compared. Results: The results revealed the highest von Mises stress of 620.14 kPa and the lowest deformation of 0.16 mm in the PDL when using the hyperelastic model. The concentration of the stress in the elastoplastic and viscoelastic models was in the mid-root and apex of the PDL, while for the hyperelastic model, it was concentrated in the cervical margin. The highest deformation in the PDL regardless of the employed material model was located in the caudal direction of the tooth. The viscoelastic PDL absorbed the transmitted energy from the dentine and led to lower stress in the cancellous bone compared to the elastoplastic and hyperelastic material models. Conclusion: These results have implications not only for understanding the stresses and deformations in the PDL under chewing but also for providing comprehensive information for the medical and biomechanical experts in regard of the role of the material models being used to address the mechanical behavior of the PDL in other components of the tooth.

Background: A finite element model was used to investigate the effect of different designs and thicknesses of orthodontic aligner margins on their biomechanical behavior., Methods: A three-dimensional data set of an upper jaw was imported into the 3-matic software. The upper right central incisor tooth (Tooth 11) was separated from the remaining model, and its periodontal ligament and surrounding bone were designed. Aligners were designed with four different trimming lines (scalloped, straight, scalloped extended, straight extended), each with four different thicknesses (0.3, 0.4, 0.5, and 0.6 mm). The models were imported into a finite element package (Marc/Mentat). A linear elastic constitutive material model was applied. A facial 0.2 mm bodily malalignment of tooth 11 was simulated., Results: The maximum resultant force was in the range of 1.0 N to 2.2 N. The straight trimming designs deliver higher resultant forces compared with scalloped trimming designs. Increasing the aligner thickness and/or extending the aligner edge beyond the gingival line leads to an increase in the resultant force. All designs showed an uneven distribution of the normal contact forces over the tooth surface with a predominant concentration toward the cervical third and distal third, particularly with the extended trimming designs. All designs showed uncontrolled tipping of the tooth., Conclusions: Based on the current model outcomes, the use of a straight extended trimming line design for aligners is favored because of its positive impact on force distribution and, consequently, the control of tooth movement., Clinical Relevance: These findings provide aligner companies and orthodontists a valuable biomechanical evidence and guidance to enhance control over tooth movement and therefore optimize treatment outcomes. This can be achieved by trimming the edges of aligners with a straight extended design and selecting the appropriate aligner thickness., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Background and Objective: To compare a single treatment of PDL-PDT with PDT for BCCs in terms of efficacy, aesthetic outcome, and pain in patients with multiple BCCs., Study Design/materials and Methods: A prospective, controlled, intra-individual, investigator-blinded study was conducted on 15 patients with 62 BCCs. The BCCs on an individual patient were divided into two similarly-sized groups, and treated with PDT (630nm LED light source, fluence rate=30mW/cm 2 , total dose of 150J/cm 2 ) and 585 nm-PDL-PDT (spot size=7mm, fluence=10J/cm 2 , pulse duration=10ms, 10% overlap, three passes, and cooling). Primary outcomes were complete BCC regression at months 3 and 12. Secondary outcomes were pain immediately after treatment, and aesthetic outcome evaluated by a blinded investigator., Results: No significant difference was found in the therapeutic effect between the two treatments (P=0.285). Complete regression of BCCs at 3-months follow-up occurred in 79% of the PDT treated area and 74% of the PDL-PDT area. At month 12, complete regression using PDT was 75% (95% confidence interval (CI) 0.55-0.89) compared to 59% (95% CI 0.41-0.75) for the PDL-PDT treated areas. Both treatments had low mean pain scores: 1.7 for PDT and 2.6 for PDL-PDT (P=0.049) and the aesthetic appearance was similar (P=0.763)., Conclusion: A single treatment with three passes of PDL-PDT is effective in clearing BCCs, but the recurrence rate is higher than in case of conventional PDT. PDL-PDT is associated with low treatment related pain, has similar cosmetic advantages as PDT but it requires less treatment time., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Unlike treatments for most rickets, the treatment using 1,25-(OH)2 vitamin D3 has little efficacy on patients with hypophosphatemic rickets, a set of rare genetic diseases. Thus, understanding the local cause for osteomalacia in hypophosphatemic rickets and developing an effective treatment to restore mineralization in this rare disease has been a longstanding goal in medicine. Here, we used Dmp1 knockout (KO) mice (whose mutations led to the same type of autosomal recessive hypophosphatemic rickets in humans) as the model in which the monoclonal antibody of sclerostin (Scl-Ab) was tested in two age groups for 8weeks: the prevention group (starting at age 4weeks) and the treatment group (starting at age 12weeks). Applications of Scl-Ab greatly improved the osteomalacia phenotype (>15%) and the biomechanical properties (3-point bending, ~60%) in the treated long-bone group. Our studies not only showed improvement of the osteomalacia in the alveolar bone, which has the highest bone metabolism rate, as well as the long bone phenotypes in treated mice. All these improvements attributed to the use of Scl-Ab are independent of the change in serum levels of phosphorus and FGF23, since Scl-Ab had little efficacy on those parameters. Finally, we propose a model to explain how Scl-Ab can improve the Dmp1 KO osteomalacia phenotype, in which the sclerostin level is already low., (Copyright © 2016 International Society of Matrix Biology. Published by Elsevier B.V. All rights reserved.)

Background: Vascular-acting photodynamic therapy (PDT) might be an alternative approach for treating port wine stain (PWS) birthmarks, but the usefulness of PDT for pediatric patients has not been fully investigated., Study Design: Medical records of pediatric patients (3-10 years old) with red and purple facial PWS were analyzed. Clinical outcomes after one session of PDL (585 nm, 4.8-6.5 J/cm(2)) and PDT (Hemoporfin - 3.5mg/kg, copper vapour laser - 120 J/cm(2)) were compared., Results: The rate of excellent response in PDT group was significantly higher than that in PDL group (25.0% vs 10.9%). For red lesions there was no significant difference in overall response between PDL and PDT group, but for purple lesions the overall response rate of PDT group was significantly higher than that of PDL group (93.0% vs 75.6%). Lesions located at the forehead, cheek and jaw regions showed better responses to PDT. Incidences of pigmentation and scar formation in PDT group were significantly lower than PDL group (8.3% vs 21.1%)., Conclusion: This study suggests that PDT is safe and effective for treating facial PWS of childhood patients., (Copyright © 2014. Published by Elsevier B.V.)

The purpose of this review is to investigate the use of Pulsed Dye Laser (PDL) as a therapeutic tool for hypertrophic burns scarring. The difference between keloids and hypertrophic scars is first described. The review then outlines the progress and assessment of hypertrophic scars for burns patients and the problem of their clinical management. The assessment using both objective and subjective measurements for complete account of hypertrophic scars is explained. The efficacy of PDL for both prevention and treatment is summarised for all hypertrophic scarring and the various laser treatment protocols in previous research is studied. The differentiation between prevention and treatment is discussed in relation to scar duration and the need for prevention rather than treatment is then proposed for intervention using PDL. The paper concludes with recommendations for future research through a prospective randomised, controlled study using 595 nm PDL in the prevention of scars with less than 6 month duration., (Copyright © 2014 Elsevier Ltd and ISBI. All rights reserved.)

Previous studies have confirmed the therapeutic effects of bone marrow stromal cells (BMSCs) transplantation on cerebral ischemia. However, the proliferative, differentiative, and homing capacity of BMSC from the elderly are significantly reduced, especially after several passages expansion in vitro. In this study, by introducing lentivirus-mediated hTERT and VEGF genes to modify human BMSCs from aged donors, we observed extended lifespan, promoted angiogenic capacity while less enhanced tumorigenicity of the genetically engineering BMSCs. These results therefore suggest that the modification of aged BMSCs by dual expression of hTERT and VEGF may be used for autologous cell replacement for ischemic cerebrovascular disease in elderly patients., (Copyright © 2013 Elsevier Inc. All rights reserved.)

Recent studies have revealed that the sympathetic nervous system is involved in bone metabolism. We previously reported that noradrenaline (NA) suppressed K(+) currents via Gi/o protein-coupled alpha1B-adrenergic receptor (α1B-AR) in human osteoblast SaM-1 cells. Additionally, it has been demonstrated that the intracellular Ca(2+) level ([Ca(2+)]i) was increased by NA via α1B-AR. In this study, we investigated the signal pathway of NA-induced [Ca(2+)]i elevation by using Ca(2+) fluorescence imaging in SaM-1 cells. NA-induced [Ca(2+)]i elevation was suppressed by pretreatment with a PLC inhibitor, U73122. This suggested that the [Ca(2+)]i elevation was mediated by Gq protein-coupled α1B-AR. On the other hand, NA-induced [Ca(2+)]i elevation was completely abolished in Ca(2+)-free solution, which suggested that Ca(2+) influx is the predominant pathway of NA-induced [Ca(2+)]i elevation. Although the inhibition of K(+) channel by NA caused membrane depolarization, the [Ca(2+)]i elevation was not affected by voltage-dependent Ca(2+) channel blockers, nifedipine and mibefradil. Meanwhile, NA-induced [Ca(2+)]i elevation was abolished following activation of store-operated Ca(2+) channel by thapsigargin. Additionally, the [Ca(2+)]i elevation was suppressed by store-operated channel inhibitors, 2-APB, flufenamate, GdCl3 and LaCl3. These results suggest that Ca(2+) influx through store-operated Ca(2+) channels plays a critical role in the signal transduction pathway of Gq protein-coupled α1B-AR in human osteoblasts., (Copyright © 2013 Elsevier Inc. All rights reserved.)