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woven bone [keywords]
- [Osteoconductive Behaviour of beta-Tricalcium Phosphate Ceramics in Osteoporotic, Metaphyseal Bone Defects of the Distal Radius]. [English Abstract, Journal Article]
- Handchir Mikrochir Plast Chir 2014 Feb; 46(1):12-7.
Surgical treatment of osteoporotic distal radius fractures with locking plates does not completely prevent loss of reduction. Additional bone deficit stabilisation with the use of bone substitute materials is receiving increased attention. Most knowledge on the in vivo behavior of bone substitutes originates from a small number of animal models after its implantation in young, good vascularized bone.This paper investigates the osteoconductivity, resorption and biocompatibility of beta-tricalcium phosphate as a temporary bone replacement in osteoporotic type distal radius fractures. 15 bone samples taken from the augmented area of the distal radius of elderly people during metal removal were examined. The material was found to be osteoconductive, good degradable, and biocompati-ble. Degrading process and remodelling to woven bone seem to require more time than in available comparative bioassays.The material is suitable for temporary replacement of lost, distal radius bone from the histological point of view.
- Negotiating the severely resorbed extraction site: A clinical case report with histologic sample. [Journal Article]
- Quintessence Int 2014; 45(3):203-8.
The treatment of an infected socket with a severe facial dehiscence/ fenestration defect presents a therapeutic dilemma to the dental team. Both implant-supported restoration and fixed partial denture are viable options to restore function and occlusion, each with its benefits and disadvantages. In the present case report, a multi-stage regenerative approach was selected to enable implant-supported single crown. The first phase of the treatment after extraction of the maxillary central incisor was the stabilization of the blood clot with a collagen plug. Six weeks later, the surgical site was re-entered and the socket was grafted with biphasic calcium sulfate (BCS). Six months later, a dental implant was placed and a core biopsy taken. However, the central portion of the facial defect demonstrated only partial regeneration resulting in exposure of six implant threads. Freeze-dried bone allograft (FDBA) and a collagen membrane were utilized to augment the ridge and cover the exposed threads. The histology of the bone core showed a complete resorption of the grafted material with the presence of new woven bone throughout the specimen. Clinically, complete defect regeneration and augmentation of the alveolar ridge were attained after 4 months. Thus, the clinician should consider the pros and cons of this regenerative approach along with other more conservative treatment alternatives when dealing with similar cases.
- Continuous and intermittent exposure of neonatal rat calvarial cells to PTHrP (1-36) inhibits bone nodule mineralization in vitro by downregulating bone sialoprotein expression via the cAMP signaling pathway. [Journal Article]
- F1000Res 2013.:77.
The development and growth of the skeleton in the absence of parathyroid-hormone-related protein (PTHrP) is abnormal. The shortening of appendicular bones in PTHrP gene null mice is explained by an effect of PTHrP on endochondral bone growth. Whether or not PTHrP influences intramembranous ossification is less clear. The purpose of this study was to determine the effect of exogenous PTHrP on intramembranous ossification in vitro. Neonatal rat calvarial cells maintained in primary cell culture conditions that permit spontaneous formation of woven bone nodules by intramembranous ossification were studied. The expression of PTHrP, parathyroid hormone 1 receptor (PTH1R), and alkaline phosphatase (AP) by osteogenic cells in developing nodules and the effects of PTHrP (1-36) on nodule development was determined over 3-18 days. PTHrP and PTH1R were detected colonies of osteogenic cells on culture day three, and AP was detected on day six. PTHrP and its receptor were localized in pre-osteoblasts, osteoblasts, and osteocytes, and AP activity was detected in pre-osteoblasts and osteoblasts but not osteocytes. Continuous and intermittent exposure to PTHrP (1-36) decreased the number of mineralized bone nodules and bone sialoprotein (BSP) mRNA and protein, but had no effect on the number of AP-positive osteogenic cell colonies, cell proliferation, apoptosis, or osteopontin (OPN) mRNA. These results demonstrate that osteogenic cells that participate in the formation of woven bone nodules in vitro exhibit PTHrP and PTH1R before they demonstrate AP activity. Exogenous PTHrP (1-36) inhibits the mineralization of woven bone deposited during bone nodule formation in vitro, possibly by reducing the expression of BSP.
- Segmental odontomaxillary dysplasia. [Journal Article]
- J Indian Soc Pedod Prev Dent 2014 Jan-Mar; 32(1):83-6.
Segmental odontomaxillary dysplasia is a type of hemi-maxillofacial dysplasia. It is a sporadic, mesoectodermal dysplasia that presents early in life, possibly as early as in utero and exhibits male gender predominance (1.7:1.0). Its features include enlargement of the soft tissue and/or bone of one hemimaxilla that may produce mild facial asymmetry, sclerotic radiographic bone changes and dental developmental abnormalities. The dense bone, which often exhibits a radiographic vertical orientation of the trabecular bone pattern, is generally associated with delayed eruption of the teeth. Congenitally missing premolar teeth (eithe or both) is a common feature of this condition that is of significant diagnostic value. Ipsilateral cutaneous findings have been reported in 23% of cases. Immature woven bone forming irregular patterns are seen histologically. Herein, we present a case report on segmental odontomaxillary dysplasia in a 13-year-old boy.
- Mandibular reconstruction with a bioactive-coated cementless Ti6Al4V modular endoprosthesis in Macaca fascicularis. [JOURNAL ARTICLE]
- Int J Oral Maxillofac Surg 2014 Feb 4.
The titanium mandibular modular endoprosthesis fixed with polymethylmethacrylate cement in the medullary space of the mandible has been introduced in previous studies. However, the internal parts of these devices have been found to be prone to loosening and wound dehiscence. The current study introduces a newly designed bioactive-coated cementless modular mandibular endoprosthesis, which was used for reconstruction in Macaca fascicularis. The devices were coated with hydroxyapatite (HA) and hydroxyapatite/bioglass (HA/BG) and implanted in unilateral mandibular segmental defects in nine monkeys for 6 months. Biomechanical testing found the reconstructed mandible to have a mean stiffness value of 110.43N/mm. Histologically, there were both fibrous capsule and woven bone around the device body, and histomorphology analysis showed 64.17% bone contact to device stem surface. The percentage bone volume calculated from micro-computed tomography analysis around the stem surface was found to be superior to that reported in previous studies of cemented mandibular endoprostheses. Intermodular connection screw loosening has also been resolved with the dovetail interconnection. In conclusion, the current bioactive-coated cementless mandibular endoprosthesis is feasible for use in mandibular segmental reconstruction. However, insufficient load-bearing capability and a high rate of intraoral wound dehiscence were found in the majority of the study animals. Further device modifications and improvements in the surgical technique need to be addressed in future studies.
- Clinical, radiographic, and histological analyses of calcium phosphate cement as filling material in maxillary sinus lift surgery. [JOURNAL ARTICLE]
- Clin Oral Implants Res 2014 Feb 6.
The installation of dental implants in the posterior maxilla is often faced with resorbed alveolar processes, resulting from a combination of pneumatization of the maxillary sinus, the effects of periodontal disease, and physiological bone resorption. The sinus lift surgery has been practiced since 1980 with the aim to increase bone height in this region for an implant supported prosthetic rehabilitation, and various filling materials have been used for such.This study aimed to clinically, radiographically, and histologically evaluate a preparation of calcium phosphate cement (Bone Source(®) , BS) used as filling material in maxillary sinus elevation surgery.Ten patients were operated requiring maxillary sinus graft for future placement of osseointegrated implants. After a period ranging from 9 to 16 months, a clinical evaluation and biopsy of the grafted area in the region adjacent to the axis of the implant to be inserted were performed.Clinically and radiographically, no evidence of resorption/substitution of BS was noticed. Although no patients have had postoperative complications and the material presented fully biocompatible characteristics with woven bone in intimate contact with BS, it was not possible to place any implants due to minimal bone formation and friability of the material.It was concluded that despite the osteoconductive capacity of BS, this conventional calcium phosphate preparation does not support sufficient amount of new bone formation that could allow its use as filling material for maxillary sinus floor lift and subsequent dental implant placement.
- Special pattern of endochondral ossification in human laryngeal cartilages: X-ray and light-microscopic studies on thyroid cartilage. [JOURNAL ARTICLE]
- Clin Anat 2014 Feb 4.
Endochondral ossification is a process that also occurs in the skeleton of the larynx. Differences in the ossification mechanism in comparison to growth plates are not understood until now. To get deeper insights into this process, human thyroid cartilage was investigated by the use of X-rays and a series of light-microscopic stainings. A statistical analysis of mineralization was done by scanning areas of mineralized cartilage and of ossification. We detected a special mode of endochondral ossification which differs from the processes in growth plates. Thyroid cartilage ossifies very slowly and in a gender-specific manner. Compared with age-matched women, bone formation in thyroid cartilage of men is significantly higher in the age group 41-60 years. Endochondral ossification is prepared by internal changes of extracellular matrix leading to areas of asbestoid fibers with ingrowing cartilage canals. In contrast to growth plates, bone is deposited on large areas of mineralized cartilage, which appear at the rims of cartilage canals. Furthermore, primary parallel fibered bone was observed which was deposited on woven bone. The predominant bone type is cancellous bone with trabeculae, whereas compact bone with Haversian systems was seldom found. Trabeculae contain a great number of reversal and arresting lines meaning that the former were often reconstructed and that bone formation was arrested and resumed again with advancing age. It is hypothesized that throughout life trabeculae of ossified thyroid cartilage undergo adaptation to different loads due to the use of voice. Clin. Anat., 2014. © 2014 Wiley Periodicals, Inc.
- Effects of calcium phosphate (CaP)/chitosan composite on bone healing in rats: Calcium phosphate induces osteon formation. [JOURNAL ARTICLE]
- Tissue Eng Part A 2014 Jan 27.
Vascularisation of an artificial graft represents one of the most significant challenges facing the field of bone tissue engineering. Over the past decade, strategies to vascularise artificial scaffolds have been intensively evaluated using osteoinductive calcium phosphate (CaP) biomaterials in animal models. In this work, we observed that CaP-based biomaterials implanted into surgical rat calvarial defects showed remarkably accelerated formation and mineralization of new woven bone in defects in the initial stages, at a rate of 60 m/day (0.8 mg/day), which was considerably higher than normal bone growth rates (several m/day, 0.1 mg/day) in implant free controls of the same age. Surprisingly, we also observed histological evidence of primary osteon formation, indicated by ectopic blood vessels in early-region fibrous tissue, which was encapsulated by lamellar osteocyte structures. These were later fully replaced by compact bone, indicating complete regeneration of calvarial bone. Thus, the CaP biomaterial used here is not only osteoinductive, but vasculogenic, and may have contributed to the bone regeneration, despite an absence of osteons in normal rat calvaria. Further investigation will involve how this strategy can regulate formation of vascularised cortical bone such as by control of degradation rate, and use of models of long, dense bones, to more closely approximate repair of human cortical bone.
- Osteitis is a misnomer: a histopathology study in primary chronic rhinosinusitis. [JOURNAL ARTICLE]
- Int Forum Allergy Rhinol 2014 Jan 21.
The histological features of osteitis in chronic rhinosinusitis (CRS) in animal studies induced by bacterial inoculation into maxillary sinuses revealed inflammatory involvement of the underlying bone matrix and/or the Haversian system; however, human studies do not mention these findings. The objective of this study was to investigate the inflammatory characterization of osteitis in CRS.A prospective study of primary CRS patients undergoing sinus surgery was conducted (August 2012 to April 2013). Bone-mucosa samples were taken from a predetermined site that correlated to a computed tomography location. Radiological bone thickness was measured. A blinded histopathological assessment included inflammatory infiltrate of bone, periosteal reaction, presence of osteoblasts or osteoclasts, fibrosis, and the percentage of new woven bone to total bone thickness, together with an overall opinion of whether neo-osteogenesis was present.Twenty-two primary CRS patients (age 45.8 ± 15.6 years; 59.1% female) were recruited. CRS with polyps accounted for 59.1% of patients. The bony thickness measured radiologically was a median 1.72 (interquartile range [IQR], 2.38; range, 0.3-12.14) mm. No samples (0%) had evidence of inflammatory infiltrate of bone; 90.9% had both osteoblasts present and new woven bone formation. Woven bone was greater with periosteal reaction (80.83% ± 9.25% vs. 47.50% ± 29.37%; p = 0.006), greater with osteoclasts present (80.00% ± 12.58% vs 59.00% ± 28.52%; p = 0.03), and greater when fibrosis was present (69.75% ± 24.14% vs 25.00% ± 7.07%; p = 0.003).Most primary CRS patients demonstrated evidence of new woven bone formation. True "osteitis" with inflammatory infiltrate of the bone was not observed. "Osteitis" is likely a process of neo-osteogenesis and bone remodeling, rather than bone inflammation in primary CRS.
- Osteolytic bone metastasis is hampered by impinging on the interplay among autophagy, anoikis and ossification. [Journal Article, Research Support, Non-U.S. Gov't]
- Cell Death Dis 2014.:e1005.
Here we show that the fate of osteolytic bone metastasis depends on the balance among autophagy, anoikis resistance and ossification, and that the hepatocyte growth factor (HGF) signaling pathway seems to have an important role in orchestrating bone colonization. These findings are consistent with the pathophysiology of bone metastasis that is influenced by the cross-talk of supportive and neoplastic cells through molecular signaling networks. We adopted the strategy to target metastasis and stroma with the use of adenovirally expressed NK4 (AdNK4) and Dasatinib to block HGF/Met axis and Src activity. In human bone metastatic 1833 cells, HGF conferred anoikis resistance via Akt and Src activities and HIF-1α induction, leading to Bim isoforms degradation. When Src and Met activities were inhibited with Dasatinib, the Bim isoforms accumulated conferring anoikis sensitivity. The proviability effect of HGF, under low-nutrient stress condition, was related to a faster autophagy deactivation with respect to HGF plus Dasatinib. In the 1833 xenograft model, AdNK4 switched metastasis vasculature to blood lacunae, increasing HIF-1α in metastasis. The combination of AdNK4 plus Dasatinib gave the most relevant results for mice survival, and the following molecular and cellular changes were found to be responsible. In bone metastasis, we observed a hypoxic condition - marked by HIF-1α - and an autophagy failure - marked by p62 without Beclin-1. Then, osteolytic bone metastases were largely prevented, because of autophagy failure in metastasis and ossification in bone marrow, with osteocalcin deposition. The abnormal repair process was triggered by the dysfunctional autophagy/anoikis interplay. In conclusion, the concomitant blockade of HGF/Met axis and Src activity seemed to induce HIF-1α in metastasis, whereas the bone marrow hypoxic response was reduced. As a consequence, anoikis resistance might be hampered favoring, instead, autophagy failure and neoformation of woven bone trabeculae. Mice survival was, therefore, prolonged by overcoming an escape strategy adopted by metastatic cells by disruption of tumor-stroma coevolution, showing the importance of autophagy inhibition for the therapy of bone metastasis.