Bone phenotype of lysyl oxidase isoform knockout mice & in vitro expression of lysyl oxidase proenzyme

Thesis (D.Sc.D.)--Boston University, Goldman School of Dental Medicine, 2008 (Dept. of Periodontology and Oral Biology).Includes bibliographical references: leaves 140-148.Lysyl oxidases constitute a family of enzymes responsible for the formation of cross links in collagen and elastin. These enzymes have also been linked to pathological fibrosis. The importance of collagen in the structural and mechanical properties of bone led us to investigate the hypothesis that the absence of one or more of these enzymes could lead to a significant bone phenotype. This phenotype could resemble osteoporosis or diabetic bone disease. In addition, we tried to overexpress lysyl oxidase proenzyme in vitro. The ability to produce enough amounts of lysyl oxidase proenzyme and the ability to process it and activate it could facilitate the development of drugs that control its activity in pathological fibrosis. Bones from 12-week old mice (8 males and 8 females) with the compound genotype LOX+/-, LOXLl -/- were analyzed. 5 males of the genotype LOX+/+, LOXLl-/were also analyzed. 16 wild type mice (8 males and 8 females) were used as controls. μCT was used to analyze the trabecular and cortical bone morphology of both left femur and L5 vertebrae (n=5). The femora were subsequently subjected to mechanical testing using the twist failure in torsion. Right femurs (n=5) were used for histology and histromorphometric analysis. Tibia and fibula (n=5) were used for cross-link analysis. Two way factor ANOV A with post-hoc Tukey HSD test was used for statistical analysis. A P value of less than 0.05 was used to declare significance. μCT analysis of the trabecular bone in femur distal ... [TRUNCATED

Bone phenotype of lysyl oxidase isoform knockout mice & in vitro expression of lysyl oxidase proenzyme (II)

Dissertation (MSD) --Boston University, Goldman School of Dental Medicine, 2012 (Department of Oral Biology).Includes bibliographic references: leaves 71-77.Lysyl oxidases constitute a family of enzymes responsible for the formation of crosslinks in collagen and elastin. These enzymes have also been linked to pathological fibrosis. The importance of collagen in the structural and mechanical properties of bone led us to investigate the hypothesis that the absence of one or more of these enzymes could lead to a significant bone phenotype. This phenotype could resemble osteoporosis or diabetic bone disease. In addition, we tried to overexpress lysyl oxidase proenzyme in vitro. The ability to produce enough amounts of lysyl oxidase proenzyme and the ability to process it and activate it could facilitate the development of drugs that control its activity in pathological fibrosis. [TRUNCATED

Long-Term Impact of New Calcium-Silicate-Based Sealer on Mineral Contents and Crystallinity of Radicular Dentin: An Ex Vivo Study

Introduction. This study aimed to evaluate the long-term impact of new calcium silicate-based sealer (HiFlow Bioceramic) compared to calcium hydroxide-based sealer (Sealapex) on mineral constituents and crystallinity of radicular dentin. Methods. Roots of multirooted maxillary molars were denuded their dentin from all covered cementum then longitudinally split. The dentin segments were divided into three groups covered with either HiFlow root canal sealer or Sealapex root canal sealer or kept untreated (control group). After complete setting of sealers, the radicular dentin of each group was stored in phosphate buffer solution or deionized water for 60 days and then examined with Fourier Infrared Spectroscopy, scanning electron microscope/energy dispersed X-ray and X-ray diffraction (XRD). Results. When the dentin was stored in phosphate buffer solution, compared with untreated dentin, Fourier transform infrared spectra showed insignificant increase in the amide I and phosphate, significant increase in carbonate area, and carbonate/phosphate ratio, while there was insignificant change in phosphate/amide I ratio of HiFlow-treated dentin, whereas Sealapex induced significant decrease in amide I area, phosphate area, and phosphate/amide ratio. Both sealers induced significant increase in crystallinity index and significant decrease in crystallinity percent. Energy dispersed X-ray showed decrease in calcium content by both sealers. The phosphate content was increased by HiFlow and decreased by Sealapex. Conclusions. The mineral composition and crystallinity of dentin were insignificantly changed by the long-term HiFlow treatment, whereas, markedly changes by Sealapex

Efficacy of the Rotary Instrument XP-Endo Finisher in the Removal of Calcium Hydroxide Intracanal Medicament in Combination with Different Irrigation Techniques: A Microtomographic Study

Objectives: This study aims to evaluate the efficacy of the rotary instrument XP-endo Finisher for the removal of Ca(OH)2 aided by different irrigation regimens. Methods: Sixteen double-rooted upper premolar human teeth were selected for the study. Thirty-two canals were prepared using a ProTaper Next rotary system up to X3. Then, the canals were filled with Ca(OH)2. The volume of Ca(OH)2 inside the canals was measured by microcomputed tomography (micro-CT). After that, the teeth were randomly allocated into two experimental groups, i.e., A and B (n = 16 canals). In group A, Ca(OH)2 was removed using the master apical file (X3). In group B, Ca(OH)2 was removed using a XP-endo finisher. In half of both groups (n = 8), syringe irrigation (SI) was used, while passive ultrasonic irrigation (PUI) was used for the other half. After removal, the remaining volume of Ca(OH)2 was measured. All data were statistically analyzed using two-way ANOVA with Tukey’s post hoc test. Results: The percentages of remaining Ca(OH)2 in the apical thirds of all canals were significantly higher as compared with the middle and coronal thirds in all groups (p < 0.05). There was no significant difference between different files and techniques (p > 0.05). Clinical Significance: This study presents a new method for the removal of Ca(OH)2 from root canals

The Effect of Calcium Hydroxide, Triple Antibiotic Paste and Chlorhexidine on Pain in Teeth with Symptomatic Apical Periodontitis: A Randomised Controlled Trial

Background: One of the main reasons for post endodontic pain is the polymicrobial intracanal flora that may survive the initial disinfection. A single antimicrobial agent might not provide adequate disinfection, and an antimicrobial combination such as triple antibiotic paste was tested to achieve this goal. Aim: The study aimed to assess the efficacy of three intra-canal medicaments on post root canal preparation pain. Materials and Methods: Eighty patients with single-rooted necrotic teeth and symptomatic apical periodontitis were randomly assigned to four treatment groups (n = 20). Their preoperative pain was recorded on Wong-Baker’s FACES pain rating scale. After chemo-mechanical canal preparation, intracanal medications were applied to the groups (Group 1 (20% calcium hydroxide), Group 2 (2% chlorhexidine), Group 3 (tri-antibiotic paste), Group 4 (no medication (Control group)). Patients were instructed to record pain on the Wong-Baker FACES pain rating scale at 4, 48, 72 and 96 hrs, postoperatively. Pain scores were analyzed using a one-way ANOVA test and Tukey’s post hoc test and, if significant, Dunn’s test was used for pair-wise comparisons. The significance level was set at a p-value ≤ 0.05. Results: Tukey’s post hoc test revealed significantly lower pain scores in Group 3 compared with other groups at all follow up intervals. Dunnett’s test showed significantly lower pain in Group 3 compared with the Control group at 48, 72 and 96 hrs, postoperatively. Conclusions: Triple-antibiotic paste showed effective pain control as an intracanal medication on necrotic teeth with symptomatic apical periodontitis