Ju-Min Lee

Comparison of treatment outcome and stability between distraction osteogenesis and LeFort I osteotomy in cleft patients with maxillary hypoplasia.

The purpose of this study was to compare treatment outcome and relapse between maxillary advancement surgery with LeFort I osteotomy and maxillary distraction osteogenesis in patients with cleft lip and palate with maxillary hypoplasia. The sample consisted of a maxillary advancement surgery with LeFort I osteotomy group (group 1, N= 14, mean age, 21.7 years) and a maxillary distraction osteogenesis group (group 2, N = 11, mean age, 16.3 years). Lateral cephalograms were taken and traced at presurgery (T0), postsurgery (T1), and postretention (T2). Nine hard and four soft tissue cephalometric variables were measured. Differences in measurements at each stage, treatment outcome (T1-T0), and relapse (T2-T1) were compared between groups with independent t test. Because the amount of surgical movement could affect the amount of relapse, a difference in relapse between two groups was compared by analysis of covariance with the amount of surgical movement as a covariant. Although the amounts of forward movements of A point (P < 0.01), upper incisor (P < 0.001), and upper lip (P < 0.001) during T1-T0 were greater in group 2, there were no significant differences in the amounts of relapse (T2-T1) between the two groups. During T1-T0, counterclockwise rotation of the palatal plane was observed in group 2 as a result of downward movement of posterior nasal spine (PNS) at T1, whereas group 1 had clockwise rotation of palatal plane at T1 because of downward movement of anterior nasal spine (ANS). The amounts of relapse (T2-T1) in vertical movements of PNS and upper incisor were significantly different between the two groups (P < 0.05). The amount of required maxillary advancement, vector control of palatal plane, and vertical position of upper incisor would be important factors when planning a surgical treatment in patients with cleft lip and palate with midface hypoplasia.

Osteoblastic response to the hydroxyapatite/gelatin nanocomposite and bio-calcium phosphate cement

The main purpose of the developingnew CPCs by modulating their components or ratios are to develop more proper biomaterials which can adapt to the body. In the present study, the properties of newly developed HAp/Gel Nanocomposites were tested using in-vitro experiments (The toxicity test, chromosomal aberration test, cytokinesis-block micronucleus assay, RT-PCR analysis). The data from the WST-1 experiments using HAp/Gel and human osteoblastic cells showed that this material does not induces cellular death. And this material did not induced any significant changes in the structures of chromosomes. The expression pattern of integrins after treatment with CPC or HAp/Gel powder represents that the cells in CPC forms focal adhesion as the cells on adhesive culture dish, but the cells in HAp/Gel do not. By performing several set of experiments, HAp/Gel is not toxic to hFOB-1.19 human osteoblast cell and does not cause any genetic problems. In contrast to CPC, HAp/Gel promotes the final differentiation of osteoblast into osteocyte. These results represent the improved bio-mimetic properties of HAp/Gel.

Transient ipsilateral mydriasis during correction of left blowout fracture.

Mydriasis, either bilateral or unilateral, seldom occurs during reconstruction of periorbital fracture. Anisocoria, a unilateral mydriasis, requires more urgent assessment than bilateral mydriasis does. Pharmacologic agents, local anesthetic infiltration, as well as direct or indirect oculomotor nerve damage are possible causes of unilateral mydriasis. Few cases have been reported about intraoperative temporary ipsilateral mydriasis during correction of blowout fracture. We have experienced an unusual case of anisocoria and report the case with literature reviews.

The effect of biomechanical stimulation on osteoblast differentiation of human jaw periosteum-derived stem cells

BackgroundThis study was to investigate the effect of biomechanical stimulation on osteoblast differentiation of human periosteal-derived stem cell using the newly developed bioreactor.MethodsHuman periosteal-derived stem cells were harvested from the mandible during the extraction of an impacted third molar. Using the new bioreactor, 4% cyclic equibiaxial tension force (0.5xa0Hz) was applied for 2 and 8xa0h on the stem cells and cultured for 3, 7, and 14xa0days on the osteogenic medium. Biochemical changes of the osteoblasts after the biomechanical stimulation were investigated. No treatment group was referred to as control group.ResultsAlkaline phosphatase (ALP) activity and ALP messenger RNA (mRNA) expression level were higher in the strain group than those in the control group. The osteocalcin and osteonectin mRNA expressions were higher in the strain group compared to those in the control group on days 7 and 14. The vascular endothelial growth factor (VEGF) mRNA expression was higher in the strain group in comparison to that in the control group. Concentration of alizarin red S corresponding to calcium content was higher in the strain group than in the control group.ConclusionsThe study suggests that cyclic tension force could influence the osteoblast differentiation of periosteal-derived stem cells under optimal stimulation condition and the force could be applicable for tissue engineering.

A Study on Prediction of Fatigue Crack Propagation Life Using MFC Sensors

One of the most important tasks in offshore and ship structures is to avoid structural failure due to defects induced by cyclic loading and structural deterioration. While the detection technology for such flaws is essential in order to ensure the integrity of structures, it is difficult to identify and measure such defects in real time with sufficient reliability. In this regard, various structural health monitoring (SHM) techniques have been developed for detecting defects and damage from many research communities. One of the key parameters in structural integrity assessment (SIA) is a precise estimation of the stress intensity factor (SIF). The SIF is used for estimating the fatigue crack propagation life based on linear elastic fracture mechanics (LEFM). In this study, the SIF of a simple test specimen is measured in real time using a macro-fiber composite (MFC) sensor. MFC sensor is a high-performance smart material used both for actuator and sensor offering good flexibility and reliability. This study examines the feasibility of MFC sensors for an SHM application with particular attention to fatigue crack monitoring. Finally, the fatigue crack propagation life calculated by an MFC sensor is compared with experimental results.