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Item The Effects of a Pyk2 Kinase Inhibitor on the Proliferation and Differentiation of Human Dental Pulp Stem Cells(2021) McIntyre, Patrick; Bruzzaniti, Angela; Ehrlich, Ygal; Bringas, Josef; Spolnik, KennethIntroduction: Regenerative endodontic procedures are an effective treatment option for immature teeth with infected necrotic pulps to allow for healing and potential continued root development, yet challenges to ideal treatment outcomes remain. Consistent development of root length and width of dentin remains a challenge, as does development of the pulp-dentin complex. Previous in vitro studies have assessed the role of different growth factors and bioactive molecules in combination with scaffolds to potentially facilitate continued development of the pulp-dentin complex using dental pulp stem cells (DPSCs). The proline-rich tyrosine kinase 2 (Pyk2) is linked with osteoblast activity and the regulation of bone mass. Further, the Pyk2 inhibitor PF-4618433 (PF-46) has been shown in previous studies to enhance osteoblast activity and mineral deposition in vitro. However, whether Pyk2 targeting promotes the osteogenic differentiation of DPSCs remains unknown. Objective: The purpose of this study was to investigate the effect of a Pyk2 inhibitor, PF-46, on the proliferation, differentiation, and mineralization of human DPSCs. Materials and Methods: Human DPSCs were cultured in 24-well plates with α-MEM with 10% FBS, and containing 0 μM (vehicle control) or 0.1 μM, 0.3 μM, or 0.6 μM PF-46. Fresh media and treatments were replaced every 2-3 days. After 1 day incubation, cytotoxic effects were evaluated by using an MTS proliferation assay. After 4 days of treatment, direct cell counting was performed. To induce osteogenic differentiation, ascorbic acid and β-glycerol phosphate were added to the culture media and the DPSCs were cultured with PF-46 for 14 days. Then, an alkaline phosphatase (ALP) assay and mineral deposition assay were performed. Differences between treatment groups were analyzed by a one-way ANOVA followed by pair-wise tests conducted using Tukey’s multiple comparisons procedure with a 5% significance level. Results: The 0.6 μM PF-46 group had a significantly higher cell count, ALP activity and mineral deposition when compared to 0 μM PF-46. The 0.1 and 0.3 μM PF-46 groups also had significantly higher ALP activity compared to the 0 μM PF-46 group after 14 days of incubation. There was a general trend of increased differentiation and mineral deposition as the concentration of PF-46 increased from 0.1 μM to 0.6 μM. Conclusion: There was a general concentration-dependent increase in cell count, differentiation, and mineral deposition by human DPSCs as the concentration of PF-46 increased from 0 μM up to 0.6 μM, with the highest activity observed with 0.6 μM PF-46. Although further research is needed, these results suggest that strategies that target Pyk2 may potentially be used to improve the osteogenic differentiation of DPSCs to aid endodontic regeneration.Item Hounsfield unit change in root and alveolar bone during canine retraction(Elsevier, 2015-04) Jiang, Feifei; Liu, Sean S.-Y.; Xia, Zeyang; Li, Shuning; Chen, Jie; Kula, Katherine S.; Eckert, George; Department of Orthodontics and Oral Facial Genetics, IU School of DentistryINTRODUCTION: The objective of this study was to determine the Hounsfield unit (HU) changes in the alveolar bone and root surfaces during controlled canine retractions. METHODS: Eighteen maxillary canine retraction patients were selected for this split-mouth design clinical trial. The canines in each patient were randomly assigned to receive either translation or controlled tipping treatment. Pretreatment and posttreatment cone-beam computed tomography scans of each patient were used to determine tooth movement direction and HU changes. The alveolar bone and root surface were divided into 108 divisions, respectively. The HUs in each division were measured. Mixed-model analysis of variance was applied to test the HU change distribution at the P <0.05 significance level. RESULTS: The HU changes varied with the directions relative to the canine movement. The HU reductions occurred at the root surfaces. Larger reductions occurred in the divisions that were perpendicular to the moving direction. However, HUs decreased in the alveolar bone in the moving direction. The highest HU reduction was at the coronal level. CONCLUSIONS: HU reduction occurs on the root surface in the direction perpendicular to tooth movement and in the alveolar bone in the direction of tooth movement when a canine is retracted.Item Mechanical environment change in root, periodontal ligament, and alveolar bone in response to two canine retraction treatment strategies(Wiley Blackwell (Blackwell Publishing), 2015-04) Jiang, F.; Xia, Z.; Li, S.; Eckert, G.; Chen, J.; Department of Engineering Technology, School of Engineering and TechnologyOBJECTIVE: To investigate the initial mechanical environment (ME) changes in root surface, periodontal ligament (PDL), and alveolar bone due to two treatment strategies, low or high moment-to-force ratio (M/F). SETTING AND SAMPLE POPULATION: Indiana University-Purdue University Indianapolis. Eighteen patients who underwent maxillary bilateral canine retraction. MATERIAL AND METHOD: Finite element models of the maxillary canines from the patients were built based on their cone beam computed tomography scans. For each patient, the canine on one side had a specially designed T-loop spring with the M/F higher than the other side. Four stress invariants (1st principal/dilatational/3rd principal/von Mises stress) in the tissues were calculated. The stresses were compared with the bone mineral density (BMD) changes reported previously for linking the ME change to bone modeling/remodeling activities. The correlation was tested by the mixed-model anova. RESULTS: The alveolar bone in the direction of tooth movement is primarily in tension, while the PDL is in compression; the stresses in the opposite direction have a reversed pattern. The M/F primarily affects the stress in root. Three stress invariants (1st principal/3rd principal/dilatational stress) in the tooth movement direction have moderate correlations with BMD loss. CONCLUSIONS: The stress invariants may be used to characterize what the osteocytes sense when ME changes. Their distributions in the tissues are significantly different, meaning the cells experience different stimuli. The higher bone activities along the direction of tooth movement may be related to the initial volumetric increase and decrease in the alveolar bone.Item Translation of Premolars in the Dog by Controlling the Moment to Force Ration on the Crown(1968) Fortin, Jean Marc; Norman, R.; Cunningham, D.; Shafer, W.The main purpose of this investigation was to produce bodily tooth movement. A force system based on the moment to force ratio (m/p ratio) was developed and applied to the teeth by means of springs similar to those used in segmented arch technique. An histologic investigation followed the experimentation. The sample consisted of five adult dogs and a relatively young one, all males. On these dogs, light forces of 165 and 147 gms were used for a period of 17, 30 and 35 days. and heavy forces of 490, 450 and 455 gms were used for a period of 120, 107 and 106 days. An intraperitoneal injection of a vital dye, procion red H8BS, was made before placing the appliance in the mouth and used as a marker between old and new bone. Bodily tooth movement was assessed by measuring new bone apposition on the tension side. Most of the teeth did show pure bodily movement, however, slight tipping was noticed in some instances. Direct bone resorption was recorded in all the teeth moved with light and heavy forces with the exception of very few small areas of hyalinization. The only difference between light and heavy forces was in the severity of root resorption. It was found that the heavier the force, the greater was the anchorage loss. The rate of tooth movement was continuous but not constant.