Ridge Preservation With Acellular Dermal Matrix and Anorganic Bone Matrix Cell-Binding Peptide P-15 After Tooth Extraction in Humans

Background: Preventing ridge collapse with the extraction of maxillary anterior teeth is vital to an esthetic restorative result. Several regenerative techniques are available and are used for socket preservation. The aim of this study is to analyze by clinical parameters the use of acellular dermal matrix (ADM) and anorganic bovine bone matrix (ABM) with synthetic cell-binding peptide P-15 to preserve alveolar bone after tooth extraction. Methods: Eighteen patients in need of extraction of maxillary anterior teeth were selected and randomly assigned to the test group (ADM plus ABM/P-15) or the control group (ADM only). Clinical measurements were recorded initially and at 6 months after ridge-preservation procedures. Results: In the clinical measurements (external vertical palatal measurement [EVPM], external vertical buccal measurement [EVBM], and alveolar horizontal measurement [AHM]) the statistical analysis showed no difference between test and control groups initially and at 6 months. The intragroup analysis, after 6 months, showed a statistically significant reduction in the measurements for both groups. In the comparison between the two groups, the differences in the test group were as follows: EVPM = 0.83 +/- 1.53 mm; EVBM = 1.20 +/- 2.02 mm; and AHM = 2.53 +/- 1.81 mm. The differences in the control group were as follows: EVPM = 0.87 +/- 1.13 mm; EVBM = 1.50 +/- 1.15 mm; and AHM = 3.40 +/- 1.39 mm. The differences in EVPM and EVBM were not statistically significant; however, in horizontal measurement (AHM), there was a statistically significant difference (P<0.05). Conclusion: The results of this study show that ADM used as membrane associated with ABM/P-15 can be used to reduce buccal-palatal dimensions compared to ADM alone for preservation of the alveolar ridge after extraction of anterior maxillary teeth. J Periodontol 2011;82:72-79.

Behavior of magnesium in Hank's solution aimed to trabecular pattern of natural bone

An ideal artificial bone is expected to grow together with other natural bones with aid of osteoblast cells and to fade out into other natural bones at the same rate of restructuring natural bone. Magnesium is thought to be one of candidate materials, since it has a potential to enhance natural bone growth and to homogenize the implanted artificial bodies with natural bone. In the present study, we are concerned with the formation of trabecular pattern in the natural bone to consider how to reconstruct this pattan in the artificial bone made from magnesium. For that purpose, a series of experiments were perfonned to observe the chemical behavior of dipped magnesium plate and cellular magnesium in Hank's solution. A magnesium specimen is annealed at 773 - 803 K for various periods in an atmosphere to homogenize its microstructure. Mass change of magnesium is estimated by immersing it in Hank's solution. It is well known that magnesium is easily corroded by chlorine ion. Both x-ray diffraction and energy dispersed x-ray analyses were carried out in order to identify a reaction product and its chemical composition. Mass of a magnesium specimen, which was annealed at 803 K for 32.4 ks or 14.4 ks, increases after immersing it into Hank's solution for 4.5 18 Ms (1255 h). Furthermore, the cellular magnesium, which was annealed at 803 K for 1.8 ks, fanned a reacted layer with around 80 μ in thickness and it contained Mg, Ca, P, and a little bit of CI.

Breeder age and bone development in broiler chicken embryos

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Membrane-bound alkaline phosphatase from ectopic mineralization and rat bone marrow cell culture

Cells from rat bone marrow exhibit the proliferation-differentiation sequence of osteoblasts, form mineralized extracellular matrix in vitro and release alkaline phosphatase into the medium. Membrane-bound alkaline phosphatase was obtained by method that is easy to reproduce, simpler and fast when compared with the method used to obtain the enzyme from rat osseous plate. The membrane-bound alkaline phosphatase from cultures of rat bone marrow cells has a MWr of about 120 kDa and specific PNPP activity of 1200 U/tng. The ecto-enzyme is anchored to the plasma membrane by the GPI anchor and can be released by PIPLC (selective treatment) or polidocanol (0.2 mg/mL protein and 1% (w/v) detergent). The apparent optimum pH for PNPP hydrolysis by the enzyme was pH 10. This fraction hydrolyzes ATP (240 U/mg), ADP (350 U/ mg), glucose 1-phosphate (1100 U/mg), glucose 6-phosphate (340 Wing), fructose 6-phosphate (460 U/mg), pyrophosphate (330 U/mg) and (3glycerophosphate (600 U/mg). Cooperative effects were observed for the hydrolysis of PPi and beta-glycerophosphate. PNPPase activity was inhibited by 0.1 mM vanadate (46%), 0.1 mM ZnCl2 (68%), 1 mM levamisole (66%), 1 mM arsenate (44%), 10 mM phosphate (21%) and 1 mM theophylline (72%). We report the biochemical characterization of membrane-bound alkaline phosphatase obtained from rat bone marrow cells cultures, using a method that is simple, rapid and easy to reproduce. Its properties are compared with those of rat osseous plate enzyme and revealed that the alkaline phosphatase obtained has some kinetics and structural behaviors with higher levels of enzymatic activity, facilitating the comprehension of the mineralization process and its function. (c) 2006 Elsevier B.V. All rights reserved.

Contribution of matrix vesicles and alkaline phosphatase to ectopic bone formation

Endochondral calcification involves the participation of matrix vesicles (MVs), but it remains unclear whether calcification ectopically induced by implants of demineralized bone matrix also proceeds via MVs. Ectopic bone formation was induced by implanting rat demineralized diaphyseal bone matrix into the dorsal subcutaneous tissue of Wistar rats and was examined histologically and biochemically. Budding of MVs from chondrocytes was observed to serve as nucleation sites for mineralization during induced ectopic osteogenesis, presenting a diameter with Gaussian distribution with a median of 306 ± 103 nm. While the role of tissue-nonspecific alkaline phosphatase (TNAP) during mineralization involves hydrolysis of inorganic pyrophosphate (PPi), it is unclear how the microenvironment of MV may affect the ability of TNAP to hydrolyze the variety of substrates present at sites of mineralization. We show that the implants contain high levels of TNAP capable of hydrolyzing p-nitrophenylphosphate (pNPP), ATP and PPi. The catalytic properties of glycosyl phosphatidylinositol-anchored, polidocanol-solubilized and phosphatidylinositol-specific phospholipase C-released TNAP were compared using pNPP, ATP and PPi as substrates. While the enzymatic efficiency (k cat/Km) remained comparable between polidocanol-solubilized and membrane-bound TNAP for all three substrates, the k cat/Km for the phosphatidylinositol-specific phospholipase C-solubilized enzyme increased approximately 108-, 56-, and 556-fold for pNPP, ATP and PPi, respectively, compared to the membrane-bound enzyme. Our data are consistent with the involvement of MVs during ectopic calcification and also suggest that the location of TNAP on the membrane of MVs may play a role in determining substrate selectivity in this micro-compartment.

Evaluation of castor oil-based polyurethane membranes in rat bone-marrow cell culture

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Tibial dyschondroplasia and bone mineral density

This study was carried out at Faculdade de Medicina Veterinária e Zootecnia, UNESP, Botucatu-SP, Brazil. The aim was to establish the normal values of bone mineral density (BMD) expressed in millimeters of aluminum in the tibia of broiler chickens using optical densitometry of radiographs. Four hundred Cobb male chicks were reared from 1 to 40 days of age, when 40 of them were selected and the right femur-tibia articulation was radiographed. Radiographs were taken with the X-ray equipment calibrated for 45 kvp and 3.2 mAs and a focus-to-film distance of 90 cm. An aluminum phantom ASTM-6063 consisting of 20 ladder steps with graduate density was placed parallel to the area to be radiographed and used as a densitometry reference standard. Radiograph images were analyzed using the software ATHENA - SIA. The proximal growth plate of the right tibia epiphysis was used as the standard reading region. The inclination axis of the reading window was 0 and the window was 10 mm high and 40-45 mm wide, depending on the bone size. Optical densitometry values of the radiographs ranged from 1.46 to 1.77 mmAl, and the coefficient of variation was 9.93%. It was concluded that densitometry values beyond the range established in the present study might indicate the presence of bone alteration in the tibia of broilers.

Cortical Bone Stress Distribution in Mandibles with Different Configurations Restored with Prefabricated Bar-Prosthesis Protocol: A Three-Dimensional Finite-Element Analysis

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Evaluation of Bone Insertion Level of Support Teeth in Class I Mandibular Removable Partial Denture Associated With an Osseointegrated Implant: A Study Using Finite Element Analysis

Purpose: This study evaluated the influence of distal extension removable partial denture associated with implant in cases of different bone level of abutment tooth, using 2D finite element analysis.Materials and Methods: Eight hemiarch models were simulated: model A-presenting tooth 33 and distal extension removable partial denture replacing others teeth, using distal rest connection and no bone lost; model B-similar to model A but presenting distal guide plate connection; model C-similar to model A but presenting osseointegrated implant with ERA retention system associated under prosthetic base; model D-similar to model B but presenting osseointegrated implant as described in model C; models E, F, G, and H were similar to models A, B, C, and D but presenting reduced periodontal support around tooth 33. Using ANSYS 9.0 software, the models were loaded vertically with 50 N on each cusp tip. For results, von Mises Stress Maps were plotted.Results: Maximum stress value was encountered in model G (201.023 MPa). Stress distribution was concentrated on implant and retention system. The implant/removable partial denture association decreases stress levels on alveolar mucosa for all models.Conclusions: Use of implant and ERA system decreased stress concentrations on supporting structures in all models. Use of distal guide plate decreased stress levels on abutment tooth and cortical and trabecular bone. Tooth apex of models with reduced periodontal support presented increased stress when using distal rest. (Implant Dent 2011;20:192-201)

Frontal sinus obliteration with heterogeneous corticocancellous bone versus spontaneous osteoneogenesis in monkeys (Cebus apella): Histologic analysis

Purpose: In this study, we evaluated the results of spontaneous osteoneogenesis of the frontal sinus with autogenous bone plug versus obliteration with heterogeneous (human) bone in monkeys (Cebus apella).Materials and Methods: Eight young adult male C apella monkeys underwent an ostectomy of the anterior wall of the frontal sinus, removal of the sinus mucosa, and inner decortication of the bony walls and then were divided into 2 groups of 4 each, as follows. Group I monkeys underwent obliteration of the nasofrontal ducts with a free segment of frontallis muscle and corticocancellous heterogeneous bone, followed by full obliteration of the sinus with corticocancellous heterogeneous bone (Dayton Regional Tissue Bank, Dayton, OH). Group II monkeys underwent obliteration of the nasofrontal ducts with a frontal muscle segment and tibial autogenous bone plug, without full obliteration of the frontal sinus. In all animals, the sinus anterior wall was repositioned and fixed with 1.0 plate and screws. The monkeys were killed after 180 days, and routine laboratory procedures were followed for hematoxylin-eosin staining and histologic evaluation of the specimens.Results: the 2 studied techniques were both effective in obliterating the frontal sinus with newly formed bone. The nasofrontal ducts were obliterated by new bone formation or fibrous tissue (1 animal only).Conclusions: Both methods used for frontal sinus obliteration were effective; the heterogeneous bone (human bone) was well tolerated and presented low antigenicity. The nasofrontal duct obliteration with autogenous muscle associated with autogenous tibial bone (group II) or with heterogeneous bone (group I) was effective, isolating the frontal sinus from the nasal cavity. The spontaneous obliteration resulted, in the period analyzed, in earlier bone maturation compared with the obliteration by heterogeneous bone. (C) 2003 American Association of Oral and Maxillofacial Surgeons.

Low-level laser on femoral growth plate in rats

OBJETIVO: Determinar a influência do Laser Terapêutico de Baixa Potência sobre a placa de crescimento de ratos. MÉTODOS: Trinta ratos Wistar machos com 40 dias de idade foram divididos em dois grupos, G1 e G2. O grupo G1 foi submetido à irradiação com laser GaAlAs 830 nm, potência de saída de 40 mW, e densidade de energia de 10 J/cm2. A irradiação foi aplicada diariamente por um período máximo de 21 dias. O mesmo procedimento foi realizado no grupo G2, com a probe desativada. Cinco animais em cada grupo foram sacrificados nos dias 7, 14 e 21 e submetidas à análise histomorfométrica. RESULTADOS: em ambos os grupos, o disco fisário esteve radiograficamente visível em todos os momentos nas incidências craniocaudal e médio-lateral. No 21º dia a porcentagem de comprimento longitudinal do fêmur foi maior em G1 que em G2 em relação ao valor basal, e o número de condrócitos da zona hipertrófica foi maior em G1 que em G2. A zona de cartilagem calcificada estava maior em G1 em relação a G2 em todos os momentos de avaliação. A angiogênese foi maior em G1 que em G2 nos 14º e 21º dias. CONCLUSÃO: A terapia com laser terapêutico de baixa potência influenciou negativamente o disco fisário distal do fêmur de ratos.

Influence of different durations of estrogen deficiency on alveolar bone loss in rats

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Evaluation of two morphometric methods of bone loss percentages caused by periodontitis in rats in different locations

Objective: The present study evaluated morphometrically bone loss percentages in experimental periodontitis in rats, comparing different locations (lingual mandible, palatal maxilla and buccal maxilla) and two evaluation methods (distance and area methods). Material and Methods: Ligatures were placed around the maxillary right second molar and around the mandibular right first molar in 14 female Wistar rats. The contralateral molars served as intragroup control. After 4 weeks, the rats were sacrificed and their mandible and maxilla were removed. The specimens were dissected and stained with methylene blue dye. Bone loss was evaluated by two different methods on the surfaces of the defleshed jaw. In the first method, the distance from the cementoenamel junction (CEJ) to the alveolar bone crest was measured in the roots of teeth associated with ligature. In the second method, the area of bone loss was determined using the alveolar tissue bone, CEJ and the proximal region of roots associated with the ligature as reference. The data were converted to bone loss percentages caused by ligature: (ligated - unligated) x 100/ligated. Results: When comparing the distance and area methods, no statistically significant difference was observed (p>0.05). Both methodologies indicated that the maxilla presented greater bone loss than the mandible and it was more accentuated on the buccal side than on the palatal side (p<0.05). Conclusions: The findings of this study show that both the area and the distance methods can be used to evaluate bone loss caused by ligature placement in rats, and suggest applying the morphometric methodology to the maxilla on the buccal side.

Ultrastructural and histochemical examination of alveolar bone at the pressure areas of rat molars submitted to continuous orthodontic force

It is usually believed that repair in alveolar bone during orthodontic movement occurs after decreasing of force. However, we have recently observed signs of repair in previously resorbed cementum from human teeth exposed to continuous forces. In order to test the hypothesis that bone resorption and deposition occur concomitantly at the pressure areas, a continuous 15 cN force was applied in a buccal direction to upper first molars from eight 2.5-month-old male Wistar rats for 3 d (n=4) and 7 d (n=4). As a control, two additional rats did not have their molars moved. Maxillae were fixed in 2% glutaraldehyde + 2.5% formaldehyde, under microwave irradiation, decalcified in ethylenediaminetetraacetic acid, and processed for transmission electron microscopy. Specimens from one rat from each group were processed for tartrate-resistant acid phosphatase (TRAP) histochemistry. At both the times studied, the alveolar bone surface at the pressure areas showed numerous TRAP-positive osteoclasts, which were apposed to resorption lacunae. In addition, osteoblasts with numerous synthesis organelles were present in the neighboring areas overlying an organic matrix. Thus, this study provides evidence that the application of continuous forces produces concomitant bone resorption and formation at the pressure areas in rat molars.

KINETIC-PROPERTIES OF OSSEOUS PLATE ALKALINE-PHOSPHATASE FROM DIABETIC RATS

1. Increased levels of bone alkaline phosphatase activity were observed in diabetic rats. These animals exhibited impaired bone development without concomitant alterations of the sequence of cellular transformations.2. Alkaline phosphatase activity was delayed in diabetic rats but the kinetic parameters for the hydrolysis of p-Nitrophenylphosphate (PNPP) were virtually the same observed for controls (N = 1.2 and K0.5 = 43 muM).3. Alkaline phosphatase from diabetic rats had a better affinity (K0.5 = 38 muM) for magnesium ions than controls (K0.5 = 9 1 muM).4. Zinc ions affected alkaline phosphatase activity from control and diabetic rats in the same way (K0.5 = 10 muM).