Associations of pretreatment parameters with changes during orthodontic treatment.

OBJECTIVES: To examine whether pretreatment conditions of a patient can determine alveolar bone changes after orthodontic treatment. SETTING AND SAMPLE POPULATION: Cone beam computed tomography (CBCT) images were obtained from 44 patients (17 male and 27 female, 14.02 ± 1.29 years). MATERIAL AND METHODS: Buccal bone height (BBH), buccal bone thickness (BBT), and molar angulation (MA) of right and left maxillary molars and intermolar distance (ID) were measured using the CBCT images obtained before and after orthodontic treatment using conventional brackets and self-ligating conventional brackets. RESULTS: There was a significant change only in BBH after treatment. All posttreatment parameters had significant positive correlations with the corresponding pretreatment parameters (r2  = 0.376-0.719, P < 0.001). Most of the changes had significant negative correlations with the corresponding pretreatment parameter (r2  = 0.054-0.249, P < 0.03). The results were not significantly influenced by the different bracket types. CONCLUSION: The current findings suggest that the CBCT-based morphological information about dentition and oral bone conditions of patients can provide a better pretreatment plan to estimate the results of orthodontic treatment.

Effect of printing technology, layer height, and orientation on assessment of 3D-printed models.

BACKGROUND: Three-dimensional (3D) printing technologies have become popular in orthodontics. The aim of this study is to determine the effect of printing technology, orientation, and layer height on the accuracy of 3D-printed dental models. METHODS: The maxillary arch of a post-treatment patient was scanned and printed at different orientations (0°, 90°) and layer thicknesses (25 µm, 50 µm, 100 µm, and 175 µm) using two different printing technologies (digital light processing and stereolithography). The 120 models were digitally scanned, and their average deviation from the initial model was analyzed using 3D algorithm. A multivariable linear regression analysis was used to estimate the effect of all variables on the average deviation from the initial model for the common layer thicknesses (50/100 µm). Finally, one-way ANOVA and Tukey posthoc test was used to compare the stereolithography (SLA) 25 µm and digital light processing (DLP) 175 µm groups with the groups that showed the least average deviation in the former analysis. RESULTS: The multivariable linear regression analysis showed that the DLP 50 µm (mean ± SD: -0.022 ± 0.012 mm) and 100 µm (mean ± SD: -0.02 ± 0.009 mm) horizontally printed models showed the least average deviation from the initial model. Finally, the DLP 175 µm horizontally printed models (mean ± SD: 0.015 ± 0.005 mm) and the SLA 25 µm horizontally (mean ± SD: 0.011 ± 0.005 mm) printed models were more accurate. CONCLUSIONS: All the models showed dimensional accuracy within the reported clinically acceptable limits. The highest accuracy was observed with DLP printer, 175 µm layer thickness, and horizontal orientation followed by SLA printer, 25 µm layer thickness, and horizontal orientation.

Double Level Osteotomy Assisted by 3D Printing Technology in a Patient with Blount Disease: A Case Report.

CASE: We describe the case of a 26-year-old patient diagnosed with Blount disease. She underwent a medial oblique supracondylar biplanar closing-wedge osteotomy of the distal femur followed by a medial oblique biplanar opening-wedge osteotomy of the proximal tibia. 3D printed cutting guides were used for the procedures. At 18 months after surgery, the patient is pain-free and walks without aids. CONCLUSIONS: Using 3D printed guides allowed for accurate correction of the deformity and reduced the risk of damaging critical structures. These guides could be an appropriate alternative for the surgical treatment of patients with Blount disease.

Extensor Mechanism Allograft in Osteosarcoma of the Patella: A Case Report.

CASE: A 24-year-old female diagnosed with fibroblastic osteosarcoma of the patella underwent a total patellectomy and surgical reconstruction with a large bone-tendon allograft of the extensor mechanism and adjuvant chemotherapy. At 5 years' postoperative, the patient has adequate disease control and excellent joint function. CONCLUSIONS: Reconstruction with an extensor mechanism allograft is an appropriate alternative for patients with malignant patella tumors without tumor contamination of the joint, allowing for satisfactory knee function and disease control.

Use of spherical coordinates to evaluate three-dimensional facial changes after orthognathic surgery.

PURPOSE: This study aimed to assess the three-dimensional (3D) facial changes after orthognathic surgery by evaluating the spherical coordinates of facial lines using 3D computed tomography (CT). MATERIALS AND METHODS: A 19-year-old girl was diagnosed with class III malocclusion and facial asymmetry. Orthognathic surgery was performed after orthodontic treatment. Facial CT scans were taken before and after orthognathic surgery. The patient had a menton deviation of 12.72 mm before surgery and 0.83 mm after surgery. The spherical coordinates of four bilateral facial lines (ramal height, ramal lateral, ramal posterior and mandibular body) were estimated from CT scans before and after surgery on the deviated and opposite side. RESULTS: The spherical coordinates of all facial lines changed after orthognathic surgery. Moreover, the bilateral differences of all facial lines changed after surgery, and no bilateral differences were zero. CONCLUSION: The spherical coordinate system was useful to compare differences between the presurgical and postsurgical changes to facial lines.

p300- and Myc-mediated regulation of glioblastoma multiforme cell differentiation.

Tumorigenic potential of glioblastoma multiforme (GBM) cells is, in part, attributable to their undifferentiated (neural stem cell-like) phenotype. Astrocytic differentiation of GBM cells is associated with transcriptional induction of Glial Fibrillary Acidic Protein (GFAP) and repression of Nestin, whereas the reciprocal transcription program operates in undifferentiated GBM cells. The molecular mechanisms underlying the regulation of these transcription programs remain elusive. Here, we show that the transcriptional co-activator p300 was expressed in GBM tumors and cell lines and acted as an activator of the GFAP gene and a repressor of the Nestin gene. On the other hand, Myc (formerly known as c-Myc overrode these p300 functions by repressing the GFAP gene and inducing the Nestin gene in GBM cells. Moreover, RNAi-mediated inhibition of p300 expression significantly enhanced the invasion potential of GBM cells in vitro. Taken together, these data suggest that dedifferentiated/undifferentiated GBM cells are more invasive than differentiated GBM cells. Because invasion is a major cause of GBM morbidity, differentiation therapy may improve the clinical outcome.

PTPmu suppresses glioma cell migration and dispersal.

The cell-surface receptor protein tyrosine phosphatase mu (PTPmu) is a homophilic cell adhesion molecule expressed in CNS neurons and glia. Glioblastomas (GBMs) are the highest grade of primary brain tumors with astrocytic similarity and are characterized by marked dispersal of tumor cells. PTPmu expression was examined in human GBM, low-grade astrocytoma, and normal brain tissue. These studies revealed a striking loss of PTPmu protein expression in highly dispersive GBMs compared to less dispersive low-grade astrocytomas and normal brain. We hypothesized that PTPmu contributes to contact inhibition of glial cell migration by transducing signals in response to cell adhesion. Therefore, loss of PTPmu may contribute to the extensive dispersal of GBMs. The migration of brain tumor cells was assessed in vitro using a scratch wound assay. Parental U-87 MG cells express PTPmu and exhibited limited migration. However, short-hairpin RNA (shRNA)-mediated knockdown of PTPmu induced a morphological change and increased migration. Next, a brain slice assay replicating the three-dimensional environment of the brain was used. To assess migration, labeled U-87 MG glioma cells were injected into adult rat brain slices, and their movement was followed over time. Parental U-87 MG cells demonstrated limited dispersal in this assay. However, PTPmu shRNA induced migration and dispersal of U-87 MG cells in the brain slice. Finally, in a mouse xenograft model of intracranially injected U-87 MG cells, PTPmu shRNA induced morphological heterogeneity in these xenografts. Together, these data suggest that loss of PTPmu in human GBMs contributes to tumor cell migration and dispersal, implicating loss of PTPmu in glioma progression.