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329 records · Page 19Linked to original sources
PubMed1981

Vascular response to modified Widman flap surgery in monkeys.

Revascularization of the periodontal tissues was studied after flap surgery. Modified Widman flap procedures were performed in four young Rhesus monkeys. All premolars and molars were involved. Experimental periods covered from 1 day to 90 days. The animals were sacrificed by exsanguination and perfused through the carotid arteries with a combined solution of equal parts of India ink and 10% buffered formalin solution. After fixation and decalcification, part of the blocks were processed to obtain cleared specimens following the Spalteholtz method. The remaining blocks were processed for routine histologic examination. The findings, mainly from the cleared specimens, showed that 1 day after surgery the supraperiosteal vessels in the flap demonstrated an overt hyperemic response. Patency of the vessels in the periodontal membrane and cancellous bone was evident; however, vessels were not depicted in the exposed cortical bone, nor in the clot. Vascular continuity apical to the surgical detachment was observed. In 3 to 4 days vascular proliferation within the organizing clot was observed and anastomosis between the gingiva and cancellous bone or periodontal membrane started to develop. At 7 days anastomoses were evident and vasodilation was present throughout the tissues. At 15 days and thereafter, vascular organization started to decrease, and the only hyperemic foci remaining were associated with areas of delayed bone remodeling, cementum remodeling or persistent marginal inflammation.

Animals↗
PubMed1997

Identification of calprotectin, a calcium binding leukocyte protein, in human dental calculus matrix.

Calprotectin is a calcium binding protein produced by leukocytes, macrophages and epithelial cells, and its levels in several tissues increase during infections and in many inflamed areas, suggesting that it may be an indicator of inflammatory activity. Osteopontin is a prominent phosphorylated glycoprotein in bone matrix, having calcium binding capacity. Recently, it has been reported that calprotectin and osteopontin are present in urinary stones (pathological mineralized masses in the body), and that these proteins may be involved in their formation. Dental calculus formed by mineralization of dental plaque is an inflammatory factor which may contribute to periodontal disease. It contains many organic components involved in mineralization. We recently found osteopontin molecules in human dental calculus and suggested that the components of its matrix may be similar to those of urinary stones. In this study, we investigated the presence of calprotectin in human dental calculus by immunohistochemical and immunoblotting analyses using a specific antibody for calprotectin. After fixation and demineralization of dental calculi adhered to tooth roots, sections embedded in paraffin were immunoreacted with the antibody for calprotectin and positive immunostaining for calprotectin was observed. Dental calculus proteins were then extracted with EDTA and separated by electrophoresis on 15% polyacrylamide gels. By immunoblotting analysis, 3 or 4 bands were observed at 11, 14.5, 22-25, 28 or 36.5 kDa and these patterns corresponded to those of calprotectin subunits. When non-immune rabbit serum was used instead of calprotectin-specific antibody as a negative control, no immunoreactivity was observed. These findings indicate that calprotectin is associated not only with antibacterial action but also with calcium binding capacity during dental calculus formation.

Calcium-Binding Proteins↗
PubMed1996

Extensive calcification of the mitral valve anulus: pathology and surgical management.

Extensive calcification of the mitral valve anulus is a pathologic entity frequently associated with degenerative valvular disease. The calcification process remains localized to the anulus in 77% of the cases. It may extend, however, to the underlying myocardium. Whenever an operation is necessary for an associated valve insufficiency, the question arises whether it is preferable to repair or to replace the valve and how to manage the calcification. In the first part of this paper the pathology of this disease is studied, and in the discussion a mechanism is proposed to explain the development of the process of calcification. In the second part, a new operation is described, which comprises the temporary detachment of the leaflets, en bloc resection of the calcium deposit, annular reconstruction, and valve repair. For patients in whom the calcification extends to the myocardium a "sliding atrioplasty" of the left atrium is described, which allows the area of exposed muscular fibers to be covered. Between 1986 and 1994, among 68 patients with extensive calcification of the anulus and severe mitral valve insufficiency, 67 benefited from these repair techniques. Ages ranged from 18 to 82 years (mean 62 years). Thirty-two patients had a billowing mitral valve (Barlow), 27 a fibroelastic deficiency, and two Marfan's disease. The calcification involved more than one third of the anulus in 88% of the patients, the posterior anulus in 10.5%, and the whole anulus in 1.5%. The calcification process extended to the myocardial wall in 12% of the patients and to the papillary muscles in 4.5%. In the group of 67 valve repairs, there were two hospital deaths (2.9%), no instances of anulus dehiscence, and no early reoperations. The follow-up period extended from 4 months to 8 years (mean 3 years 8 months). There were two late deaths, 2 and 17 months after the operations, for an actuarial survival of 93% at 7 years. Late reoperation (6 to 62 months) was necessary in four patients (6.4%) for residual mitral valve incompetence (n=2), hemolysis (n=1), or endocarditis (n=1). In one of these patients a new repair was possible, whereas the three other patients required a valve replacement. All patients but one survived the reoperation. Actuarial freedom from reoperation was 87% at 7 years. All 60 patients with valve repair were reviewed for this study by clinical examination and echocardiography. All but one were in functional class I or II. There was no incompetence or trivial residual mitral valve incompetence in 55 patients and moderate incompetence in five. Two thromboembolic events have been recorded for a linearized rate of 1%/pt-yr. This study shows that complete anulus decalcification and valve repair can be done safely in patients with mitral valve insufficiency and extensive calcification of the anulus, even when the calcification process deeply involves the myocardium. It also demonstrates that an initially good result remained stable up to 7 years.

Adolescent↗
PubMed2003

Effect of 830-nm laser light on the repair of bone defects grafted with inorganic bovine bone and decalcified cortical osseous membrane.

OBJECTIVE: The aim of this study was to assess histologically the effect of LLLT (lambda830 nm) on the repair of standardized bone defects on the femur of Wistar albinus rats grafted with inorganic bovine bone and associated or not to decalcified bovine cortical bone membrane. BACKGROUND DATA: Bone loss may be a result of several pathologies, trauma or a consequence of surgical procedures. This led to extensive studies on the process of bone repair and development of techniques for the correction of bone defects, including the use of several types of grafts, membranes and the association of both techniques. There is evidence in the literature of the positive effect of LLLT on the healing of soft tissue wounds. However, its effect on bone is not completely understood. MATERIALS AND METHODS: Five randomized groups were studied: Group I (Control); Group IIA (Gen-ox); Group IIB (Gen-ox + LLLT); Group IIIA (Gen-ox + Gen-derm) and Group IIIB (Gen-ox + Gen-derm + LLLT). Bone defects were created at the femur of the animals and were treated according to the group. The animals of the irradiated groups were irradiated every 48 h during 15 days; the first irradiation was performed immediately after the surgical procedure. The animals were irradiated transcutaneously in four points around the defect. At each point a dose of 4 J/cm2 was given (phi approximately 0.6 mm, 40 mW) and the total dose per session was 16 J/cm2. The animals were humanely killed 15, 21, and 30 days after surgery. The specimens were routinely processed to wax, serially cut, and stained with H&E and Picrosirius stains and analyzed under light microscopy. RESULTS: The results showed evidence of a more advanced repair on the irradiated groups when compared to non-irradiated ones. The repair of irradiated groups was characterized by both increased bone formation and amount of collagen fibers around the graft within the cavity since the 15th day after surgery, through analysis of the osteoconductive capacity of the Gen-ox and the increment of the cortical repair in specimens with Gen-derm membrane. CONCLUSION: It is concluded that LLLT had a positive effect on the repair of bone defect submitted the implantation of graft.

Animals↗
PubMed1997

A quantitative assessment of osteoinductivity of human demineralized bone matrix.

Demineralized bone matrix (DBM) is widely used in the repair of pathologies associated with skeletal defects and periodontal diseases. The present study was directed at establishing in vivo and in vitro models for a quantitative assessment of the osteoinductivity of DBM before clinical use. Athymic mice were used in an in vivo assay to overcome the species limitations (for human DBM) found in xenogeneic animal models. Calcium contents of explants, as an indicator of new bone formation, were assayed and expressed as a change in the weight percent calcium in the explant as compared to the weight percent of calcium in the implanted material. A total of 82 mice (2 implants per mouse) were used in this study. Significant amounts of new bone were induced in this animal model in response to implantation of DBM. Muscular implantation was found to be more osteoinductive (increases of 10.0 +/- 0.4 calcium weight percent of explant) than subcutaneous implantation (increases of 1.62 +/- 0.27 calcium weight percent of explant) and new bone formation in muscular implantation sites of athymic mice mimics endochondral bone formation. Between weeks 1 to 4, the weight of explanted materials did not significantly differ from the weight of the implanted material; however, by week 5 the explant weight began to increase. Calcium deposition over the 5 weeks of implantation increased in a nearly linear fashion. Consequently week 4 was chosen as the optimum time for explantation in the in vivo assay in that sufficient calcium levels had been achieved without a significant increase in explant dry weight. Aliquots of 10, 20, 30, and 40 mg per implantation site were used in dose response studies in the in vivo bioassay. Dose response curves with DBM exhibited maximal activity at the 20 mg DBM implant dose in the in vivo bioassay. An in vitro bioassay was also developed where human periosteal (HPO) cells were chosen because osteoprogenitor cells found in bone repair typically come from periosteal tissue. Alkaline phosphatase (ALP) activity in confluent cell cultures of HPO cells exposed to DBM, as an indicator of osteoblast induction, reached its highest level on day 5 of DBM treatment. Aliquots of 2, 5, 10, 20, 30, and 40 mg DBM per flask were chosen in dose response studies using the in vitro bioassay. These dose response studies with DBM revealed that quantities approximating 5 to 10 mg DBM in the in vitro model provided for maximal levels of ALP in cell extracts. A linear correlation (R2 = 0.7397) was demonstrated between the in vivo calcium remineralization assay and the in vitro ALP assay of osteoinductivity of DBM, suggesting that the in vitro assay can be used to quantitatively assess the osteoinductive potential of DBM where production and distribution of clinically usable DBM dictates rapid analysis.

Adult↗