Dentinal Tubule Occluding Efficacy Of Er: YAG Laser And Universal Adhesive Loaded With Nano-Carbonated Apatite

Abstract ER:YAG laser and experimental resin-based dental adhesive loaded with functionalized carbonated apatite filler were used in this study to evaluate the dentin interaction in terms of penetration and occlusion of the dentinal tubules aiding in the control of dentin hypersensitivity (DH). Spheroidal Carbonated apatite nanoparticles (N-CAP), with an average size of 20±5 nm diameter, were synthesized, characterized, and incorporated in a universal adhesive "All Bond Universal, Bisco, USA", in (2% weight) concentration. Er:YAG laser "Lightwalker, FOTONA, EU" was adjusted to an energy output of 40mJ/ pulse and pulse repetition of 10 Hz for 10 seconds. Dentin specimens were prepared from the buccal surface of 75 extracted sound human molars. The specimens were randomly divided into five groups (n=15) according to the surface treatment: Group (L): Laser only; Group (LB): Laser in combination with adhesive; Group (LBN): Laser in combination with adhesive loaded with N-CAP; Group (B): adhesive only; and Group (BN): adhesive loaded with N-CAP. Depth of penetration and occlusion of the dentinal tubules were assessed using Environmental Scanning Electron Microscope Examination (ESEM). One-way ANOVA was used to compare groups, followed by a pairwise test for multiple comparisons (α=0.05). Groups (LB), and (LBN) showed the highest mean of dentinal tubules' penetration, with a non-significant difference between them. In contrast, the specimens treated with laser only (L) showed the most minor penetration. The employment of ER-YAG laser irradiation with the adhesive loaded with N-CAP was evaluated to be effective in penetrating and occluding the opened dentinal tubules.

Resumo O laser ER-YAG e o adesivo dentário experimental à base de resina carregado com carga de apatita carbonatada funcionalizada foram usados neste estudo para avaliar a interação com a dentina em termos de penetração e oclusão dos túbulos dentinários, auxiliando no controle da hipersensibilidade dentinária (HD). Nanopartículas de apatita carbonatada esferoidal (N-CAP), com tamanho médio de 20±5 nm de diâmetro, foram sintetizadas, caracterizadas e incorporadas em um adesivo universal "All Bond Universal, Bisco, EUA", na concentração de 2% em peso. O laser Er:YAG "Lightwalker, FOTONA, EU" foi ajustado para uma saída de energia de 40mJ/pulso e repetição de pulso de 10 Hz por 10 segundos. Os espécimes de dentina foram preparados a partir da superfície vestibular de 75 molares humanos sadios extraídos. Os espécimes foram divididos aleatoriamente em cinco grupos (n=15) de acordo com o tratamento da superfície: Grupo (L): Somente laser; Grupo (LB): Laser em combinação com adesivo; Grupo (LBN): Laser em combinação com adesivo carregado com N-CAP; Grupo (B): somente adesivo; e Grupo (BN): adesivo carregado com N-CAP. A profundidade de penetração e a oclusão dos túbulos dentinários foram avaliadas por meio do Exame de Microscópio Eletrônico de Varredura Ambiental (ESEM). ANOVA de um fator foi usada para comparar os grupos, seguida pelo teste de pares para comparações múltiplas (α=0,05). Os grupos (LB) e (LBN) apresentaram a maior média de penetração dos túbulos dentinários, com uma diferença não significativa entre eles. Em contraste, os espécimes tratados apenas com laser (L) apresentaram menor penetração. O emprego da irradiação do laser ER-YAG com o adesivo carregado com N-CAP foi avaliado como eficaz na penetração e oclusão dos túbulos dentinários abertos.

Ex Vivo Analysis of MTA FLOW® Biomineralization and Push-Out Strength: A Pilot Study / Análisis ex vivo del proceso de biomineralización y resistencia al desplazamiento del MTA FLOW®: Estudio piloto

Abstract: This study evaluated the biomineralization processes and push-out strength of MTA Flow® with radicular dentine in three different consistencies. The push-out test was performed on an ex vivo model, using 2mm thick dentin discs from the middle third of the root with standardized cavities of 1.5 mm. Samples were filled with MTA-Angelus (Angelus Dental, Brazil), Biodentine (Septodont, France), MTA Flow® Putty (Ultradent, USA), MTA Flow® Thick or MTA Flow® Thin. The samples were divided into 3 groups: subgroup 1 (n=5), analysis of the biomineralization process; 2 (n=20), evaluation of the bonding strength and push-out resistance; and 3 (n=5), evaluation of the cement/ dentin interface. The samples filled with Biodentine had a higher precipitation of carbonate apatite. However, there was no significant difference between MTA-Angelus, MTA Flow® Putty, or Thick (p=0.0536), but there was a significant difference in the Thin group (P<0.05). The samples with Biodentine displayed the greatest release of calcium ions. The formation of a partially carbonated intermediate apatite layer was observed in all groups. Zones of biomineralization were observed at the interface but were not continuous. After 72 hours, a significant difference was found between the Biodentine and MTA Flow® Thin groups (p=0.0090) in the push-out test. The samples submerged in phosphate-buffered saline (PBS) for 15 days showed a significant difference between all groups and MTA Flow® Thin (p=0.0147). Putty or Thick consistencies presented a similar bonding strength to MTA-Angelus and Biodentine. MTA Flow® Putty and Thick consistencies show a good adaptation to dentin, similar to MTA-Angelus. However, the thickness of the interface was lower compared to that of Biodentine. MTA Flow® Thin, despite their tubular infiltration, results in gaps and a defective peripheral seal.Therefore, MTA Flow®, in Putty or Thick consistencies, presents a biomineralization process and push-out strength similar to MTA Angelus and Biodentine, however, both characteristics decreases considerably in Thin consistency.

Resumen: El objetivo de este estudio fue evaluar, en un modelo ex vivo, el proceso de biomineralización y fuerza de adhesión del MTA Flow® en sus tres diferentes consistencias por medio de la prueba de resistencia al desplazamiento (Push-out). Se utilizaron discos de dentina de 2mm de espesor del tercio medio radicular con cavidades estandarizadas de 1.5mm de diámetro, las cuales se obturaron con diferentes materiales entre ellos: MTA Angelus (Angelus Dental, Brasil), Biodentine (Septodont, Francia), MTA Flow® Consistencia Putty (Ultradent, E.E.U.U), MTA Flow® Consistencia Thick (Ultradent, E.E.U.U) y MTA Flow® Consistencia Thin (Ultradent, E.E.U.U). Las muestras se sometieron al proceso de biomineralización y a pruebas de Push-out. Las muestras obturadas con Biodentine promovieron una mayor precipitación de apatita carbonatada, sin embargo, no se presentó diferencia estadística significativa con respecto al MTA Angelus, MTA Flow® Putty ni Thick (p=0.0536). No obstante, si presentó una diferencia significativa con respecto al grupo de MTA Flow® consistencia Thin (P<0.05). Las muestras con Biodentine presentaron la mayor liberación de iones calcio. De acuerdo a las pruebas de resistencia al desplazamiento, a las 72 horas post-obturación, solamente se encontró diferencia significativa entre las muestras obturadas con Biodentine y las correspondientes al MTA Flow consistencia Thin (p=0.0090), sin embargo las muestras sumergidas 15 días en PBS presentaron diferencia significativa entre todos los grupos con respecto al MTA Flow Thin (p=0.0147). En general se observaron zonas de biomineralización en la interface, sin embargo, no fueron continuas. Se concluye que el MTA Flow en consistencia Putty o Thick presenta un proceso de biomineralización y una resistencia al desplazamiento similar al MTA Angelus y al Biodentine, sin embargo, esta última disminuye considerablemente en presentación Thin.

Estudio comparativo de la bioactividad de dos materiales biocerámicos / Comparative Study of the Bioactivity of Two Bioceramic Materials

RESUMEN Los materiales a base de silicato de calcio han demostrado ser bioactivos debido a su capacidad para producir apatita carbonatada biológicamente compatible. El objetivo de este estudio fue analizar la bioactividad de Biodentine™ y MTA Repair HP® en contacto con discos de dentina humana, que se obturaron y dividieron aleatoriamente para formar cuatro grupos: grupo 1 Biodentine™, grupo 2 MTA Repair HP®, grupo control positivo MTA Angelus® y grupo control negativo IRM®, los cuales se incubaron en solución PBS durante 10 días, para posterior análisis por medio de MEB-EDS y Espectroscopía Raman. Los tres materiales a base de silicato de calcio analizados en este estudio demostraron ser bioactivos pues al entrar en contacto con una solución a base de fosfato desencadenaron la precipitación inicial de fosfato de calcio amorfo, que actúa como precursor durante la formación de apatita carbonatada.

ABSTRACT Calcium silicate-based materials have been shown to be bioactive due to their ability to produce biologically compatible carbonated apatite. The objective of this study was to analyze the bioactivity of Biodentine ™ and MTA Repair HP® in contact with human dentine discs, which were sealed and divided randomly to form four groups: group 1 Biodentine™, group 2 MTA Repair HP®, positive control group MTA Angelus® and negative control group IRM®, which were incubated in PBS solution for 10 days, for a subsequent analysis by means of MEB-EDS and Raman spectroscopy. The three calcium-based materials analyzed in this study proved to be bioactive because upon contact with a phosphate-based solution they were triggered at the onset of amorphous calcium phosphate, as the precursor during the formation of carbonated apatite.

Enhanced bioactive properties of BiodentineTM modified with bioactive glass nanoparticles

Abstract Objective To prepare nanocomposite cements based on the incorporation of bioactive glass nanoparticles (nBGs) into BiodentineTM (BD, Septodent, Saint-Maur-des-Fosses Cedex, France) and to assess their bioactive properties. Material and Methods nBGs were synthesised by the sol-gel method. BD nanocomposites (nBG/BD) were prepared with 1 and 2% nBGs by weight; unmodified BD and GC Fuji IX (GIC, GC Corporation, Tokyo, Japan) were used as references. The in vitro ability of the materials to induce apatite formation was assessed in SBF by X-ray diffraction (XRD), attenuated total reflectance with Fourier transform infrared spectroscopy (ATR-FTIR), and scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) analysis. BD and nBG/BD were also applied to dentine discs for seven days; the morphology and elemental composition of the dentine-cement interface were analysed using SEM-EDX. Results One and two percent nBG/BD composites accelerated apatite formation on the disc surface after short-term immersion in SBF. Apatite was detected on the nBG/BD nanocomposites after three days, compared with seven days for unmodified BD. No apatite formation was detected on the GIC surface. nBG/BD formed a wider interfacial area with dentine than BD, showing blockage of dentine tubules and Si incorporation, suggesting intratubular precipitation. Conclusions The incorporation of nBGs into BD improves its in vitro bioactivity, accelerating the formation of a crystalline apatite layer on its surface after immersion in SBF. Compared with unmodified BD, nBG/BD showed a wider interfacial area with greater Si incorporation and intratubular precipitation of deposits when immersed in SBF.

Evaluation of inorganic and organic bone components after application of an apatite-coated Al2O3 implants as scaffolds for bone repair

The aim of this work was to study the influence of uncoated and apatite-coated Al2O3 implants on bone regeneration after 30 days of surgery in New Zealand white rabbits. Twelve samples of Al2O3 implants were prepared and half of them (n = 6) were apatite-coated by the modified biomimetic method. Three experimental groups were tested as Group C - control, surgery procedure without cerami c implant, Group Ce - uncoated Al 2O3 implants (n = 6) and Group CeHA - apatite-coated Al2O3 implants (n = 6). The mineralization of the Al2O3 implants was analyzed in bone fragments using FT-Raman spectroscopy. Raman peaks at 959 cm-1 and 2940 cm-1 evaluated the inorganic and organic bone content, respectively. In vivo citotoxicity was analyzed using micronucleus test. Inorganic and organic content were higher in CeHA samples than in Ce and C (CeHA > Ce > C). FT-Raman spectroscopy showed that the higher the deposition of the organic matrix, more mineralization occurred. The micronucleus test showed that the uncoated and apatite-coated Al2O3 implants were non-cytotoxic and safe to in vivo applications.

Fabrication and properties of low-crystallinity carbonate apatite monolith bone graft / 中国组织工程研究

BACKGROUND:As a good candidate for bioresorbable bone graft, carbonate apatite monolith can be prepared by sintering procedure;however, sintering can cause carbonate loss and result in a much lower rate of biodegradation compared to the human bone, thereby influencing the formation of new bone. OBJECTIVE:To fabricate low-crystal inity carbonate apatite monolith as bone graft and test its properties. METHODS:Calcium carbonate monolith prepared by carbonation of Ca(OH) 2 monolith was treated in 1 mol/L RESULTS AND CONCLUSION:The calcium carbonate completely transformed into low-crystal inity B-type carbonate apatite after treated for 14 days. Diametral tensile strength of the final product was (10.27±1.08) MPa, which is adequate as a reconstruction material for bone defect. The carbonate content was (4.80±0.50)%, similar to that of the nature bone. The molar Ca/P was 1.63±0.01, indicating the Ca-deficient carbonate apatite is obtained. The present method al ows an easy fabrication of low-crystal inity B-type carbonate apatite block with adequate strength and without sintering process. ammonium dihydrogen phosphate solution at 60 ℃ up to 14 days. Diametral tensile strength was examined for biomechanical properties;X-ray diffraction analysis, Fourier transform infrared spectroscopy, scanning electron microscope observation and chemical analyses (carbonate, calcium and phosphate content) were also performed for physical and chemical properties.

Osteoporosis y osteosíntesis / Osteoporosis and osteosynthesis

Introducción: las manifestaciones clínicas de las osteoporosis incluyen las fracturas debido a pérdida de masa ósea y cambios estructurales en las trabéculas. En estos casos la osteosíntesis se ve afectada por los factores mecánicos inherentes al proceder y los implantes. Objetivo: mostrar las precauciones que el ortopédico necesita tener en mente al seleccionar el tipo de osteosíntesis (interna o externa) y los implantes que vaya a utilizar. Métodos: se realizó una revisión de las distintas precauciones en cirugía ortopédica sobre fracturas vertebrales y de huesos largos, así como su osteosíntesis de acuerdo a instrumental, implante y proceder operatorio. Resultados: se enfatiza en los avances incorporados, en especial, los sistemas mínimo invasivos de estabilización ósea, el uso de implantes con cerrojos"y el recubrimiento de clavos con hidroxiapatita de calcio y alambres para fijación externa. Conclusión: la osteosíntesis precoz, definitiva y eficaz, es el tratamiento de elección en las fracturas poróticas

Introduction: the clinical manifestations of osteoporosis include fractures due to a loss of bone mass and structural changes in trabeculae. In these cases the osteosynthesis is affected by the mechanical factors inherent to procedure and to implants. Objective: to show the cautions that orthopedist must to take into account at selecting the type of osteosynthesis (internal or external) and the implants to be used. Methods: a review of the different cautions in orthopedic surgery on vertebral fractures and long bones was carried out as well as its osteosynthesis according to the instrumental, the implant and operative procedure. Results: it is emphasize on the incorporated advances, specially the minimally invasive systems of bone stabilization, the use of implants with bolts and nails covering or coating with calcium hydroxyapatite and wires for external fixation. Conclusion: the early, definitive and effective osteosynthesis is the choice treatment in porous fractures

Development of chitosan/nanosized apatite composites for bone cements.

Background: Calcium phosphate cements (CPC) is a promising materials for bone defect repair. Nanosized apatite or calcium orthophosphate has a better bioactivity than coarser crystals. Chitosan is produced commercially from chitin that is the structural element in the exoskeleton of crustaceans such as crabs and shrimp. The mixing of nanosized apatite and chitosan may provide the consistency cement, improving mechanical properties of the set bone cement. Objective: Develop nanosized apatite powder with chitosan for bone composite cement. Materials and method: Nanosized apatite was synthesized by chemical method at low temperature and used as the single-component for bone cement. The nanosized apatite powder was characterized using X-ray diffraction method, Fourier transform infrared spectroscopy, and transmission electron microscopy. CPCs were developed based on chitosan/nanosized apatite and calcium sulfate hemihydrate. The compressive strength of the set cement was measured after one to four weeks. The phase composition and the morphology of the set cements were investigated. Results: Calcium sulfate hemihydrate was effective in increasing the compressive strength after setting in a simulated body fluid for seven days. The compressive strength of chitosan/nanosized apatite composite was about 18 MPa after soaking. Conclusion: The workability and setting time of this composite were suitable to handling for bone cement. These composite cements had a significant clinical advantage for substitution of the regenerated bone.

Enhancement of clover growth by inoculation of P-solubilizing fungi and arbuscular mycorrhizal fungi

This study evaluated the synergism between several P-solubilizing fungi isolates and arbuscular mycorrhizal fungi to improve clover ( Trifolium pratense) growth in the presence of Araxá apatite. Clover was sown directly in plastic pots with 300g of sterilized washed sand, vermiculite and sepiolite 1:1:1 (v:v:v) as substrate, and grown in a controlled environment chamber. The substrate was fertilized with 3 g L-1 of Araxá apatite. A completely randomized design, in 8×2 factorial scheme (eight P-solubilizing fungi treatments with or without arbuscular mycorrhizal fungi)and four replicates were used. The P-solubilizing fungi treatments consisted of five Brazilian P-solubilizing fungi isolates (PSF 7, 9, 20, 21 and 22), two Spanish isolates ( Aspergillus niger and the yeast Yarowia lipolytica) and control (non-inoculated treatment). The greatest clover growth rate was recorded when Aspergillus niger and PSF 21 were co-inoculated with arbuscular mycorrhizal fungi. Aspergillus niger, PSF 7 and PSF 21 were the most effective isolates on increasing clover growth in the presence of arbuscular mycorrhizal fungi. Greater mycorrhizal colonization resulted in greater clover growth rate in most PSF treatments. PSF 7 was the best isolate to improve the establishment of mycorrhizal and rhizobia symbiosis.

Este estudo avaliou o sinergismo entre diversos isolados defungos solubilizadores de fosfato e micorrízicos arbusculares para beneficiar o crescimento de trevo ( Trifolium pratense) na presença de apatita de Araxá. A cultura foi semeada diretamente em potes plásticos com 300 g de substrato esterilizado formado por areia lavada, vermiculita e sepiolita 1:1:1 (v:v:v) e cultivada em câmara climática. O substrato foi fertilizado com 3 g L-1 de apatita de Araxá. O experimento foi instalado em delineamento completamente casualizado, esquema fatorial 8×2 (oito tratamentos de inoculação de fungos solubilizadores de fosfato com ou sem fungos micorrízicos arbusculares) e quatro repetições. Os tratamentos de fungos solubilizadores de fosfato consistiram em cinco isolados brasileiros de fungos solubilizadores de fosfato (FSF 7, 9, 20, 21 e 22), dois isolados procedentes da Espanha ( Aspergillus niger e a levedura Yarowia lipolytica) e o controle (tratamento não inoculado). A maior taxa de crescimento da cultura foi obtida quando Aspergillus niger e FSF 21 foram co-inoculados com fungos micorrízicos arbusculares. Aspergillus niger, FSF 7 e o FSF 21 foram os isolados mais efetivos para incrementar o crescimento de trevo na presença de fungos micorrízicosarbusculares. A maior taxa de colonização micorrízica resultou em alta taxa de crescimento de trevo na maioria dos tratamentos com fungos solubilizadores de fosfato. O isolado FSF 7 foi o melhor para favorecer o estabelecimento das simbioses com fungos micorrízicos e com rizóbio.

Analysis of Biological Apatite Orientation in Rat Mandibles / Oral Science International

Recently, significant progress has been made in medical techniques for regenerating bone. However, bone evaluation techniques generally assess bone quantity as opposed to bone quality. The use of <i>c</i>-axis crystallite orientation of biological apatite (BAp) as a bone quality index has recently generated great interest. BAp demonstrates strong crystallographic anisotropy, and preferential alignment of BAp in each bone varies depending on the shape and stress conditions <i>in vivo</i>. In the mandible, complicated bone shape and stress conditions <i>in vivo</i> might be associated with both bone quantity and quality. In this study, we aimed to elucidate changes in the bone microstructure in the mandible using crystallographic orientation of BAp as a bone quality index. Using Crj: CD (SD) IGS female rats, we observed changes in the dentulous mandible during bone growth. Measuring points on the mandible were determined based on its positional relationship with the teeth. For analysis of bone quantity, the area and bone mineral density of cortical bone were evaluated using peripheral quantitative computed tomography (pQCT), while the orientation of the BAp <i>c</i>-axis, as analyzed by a micro-beam X-ray diffraction system, was used to assess bone quality. The results of both bone quantity and quality assessments indicated that changes during bone growth varied depending on the presence of teeth. We concluded that the microstructure (especially the texture) of BAp crystallite changes in correlation with variations in stress distribution <i>in vivo</i> resulting from changes in chewing conditions designed to optimize the dynamic chewing function.

Calculi in Hydrocele: Incidence and Results of Infrared Spectroscopy Analysis

Trauma, inflammation, or necrosis in the scrotal cavity may lead to depositing of organic material in hydrocele fluid with consecutive calcification if the fluid is oversaturated. During a period of 25 years, 2 scrotal calculi (calculous material in hydrocele fluid) in 2 of 42 patients (4.8%) were found during surgery on symptomatic hydroceles by the first author. In these symptomatic cases, infrared spectroscopy revealed carbonate apatite as the causative mineral. The appearance of scrotal calculi in hydrocele does not change the treatment or prognosis of hydroceles. However, if the calculous material is attached to the visceral or parietal part of the tunica vaginalis and does not change position during sonography with different postures, tumor growth may be a problem. An inguinal approach for operation should be chosen in such situations. Infrared spectroscopy can be used to determine the mineralogy of scrotal calculi. Carbonate apatite, the predominantly found mineral in scrotal calculi, can precipitate in an alkaline milieu.

Evaluación de la biocompatibilidad de apatita carbonatada de síntesis seca por medio del cultivo de células osteoprogenitoras de porcino / Biocompatibility evaluation of carbonated apatite of dry synthesis through porcine osteoprogenitors culture / Avaliação da biocompatibilidade de apatita carbonatada de síntese seca através de cultura de células osteoprogenitoras de suínos

El desarrollo de nuevos materiales para la regeneración ósea es un reto para las ciencias biomédicas, especialmente aquellos materiales sintéticos que simulan de la mejor manera los componentes del hueso natural. En este artículo se muestra los resultados de un trabajo en donde se evaluó la biocompatibilidad de la apatita carbonatada (CAp), preparada por reacción mecano-química de una mezcla de precursores en polvo, comprimida y luego horneada a altas temperaturas (llamada síntesis seca). Esta cerámica fue utilizada como sustrato en un cultivo de células osteoprogenitoras, las cuales se obtuvieron por medio de aspirados de la médula ósea de porcinos adultos, se aislaron por diluciones y se cultivaron en platos o sobre CAp con o sin la adición de factores de diferenciación osteogénica. Los cultivos se analizaron a diferentes tiempos por 45 días, periodo durante el cual se determinó el doblaje poblacional de las células y la capacidad osteoconductiva del biomaterial, a través de pruebas bioquímicas y moleculares. Como resultados de este trabajo se estableció un cultivo primario de osteoprogenitores de la médula ósea de porcino, para la evaluación in vitro de un material cerámico de síntesis por reacción del estado sólido, y se exploró el uso potencial del material como substituto del hueso natural, al analizar su capacidad osteoconductiva, por medio de microscopia óptica y electrónica y de la expresión de marcadores bioquímicos y moleculares, tales como la expresión de fosfatasa alcalina, deposición de calcio y acumulación de xilenol orange concomitante con la detección de Runx2, osteocalcina y osteopontina...

The development of new materials for bone regeneration constitutes a challenge for biomedical sciences, especially when it is desirable to design synthetic materials that simulate the most the composition of natural bone. In this work biocompatibility of carbonated apatite (CAp) was evaluated. CAp was prepared through mechano-chemical mixing, compression and sintered at high temperature (referred as dry synthesis) of powdered precursors. This ceramic was then used as a substrate for the culture of porcine osteogeprogenitors. Cells were obtained from the bone marrow of adult porcine just after sacrifice by series of dilutions. Cells were then cultured onto culture plates or onto CAp, with and without addition of known differentiation osteogenic factors. Cultures were carried out for 45 days during which the doubling time of the culture was determined as well as the osteoconductivty of CAp, by means of determining some biochemical and molecular markers. A primary culture of porcine bone marrow osteoprogenitor was established and was used for the in vitro evaluation of a ceramic material synthetised by solid state reaction. The potential use of the material as a substitute for natural bone implant was explored, by analysing its osteoconductive capacity, through light and electron microscopy and expression of biochemical and molecular markers, such as the expression of alkaline phosphatase, calcium deposition and xylenol orange accumulation, concomitant with detection of Runx2, osteocalcin and osteopontin...

O desenvolvimento de novos materiais para regeneração óssea é um desafio para as ciências biomédicas, especialmente as de materiais sintéticos que simulam da melhor maneira os componentes do osso natural. Neste artigo mostram-se os resultados de um trabalho que avaliou a biocompatibilidade de apatita carbonatada (Cap), preparada por reação mecanoquímica de uma mistura de pó precursor, comprimido e depois cozido em altas temperaturas (chamado de síntese seca). Esta cerâmica foi utilizada como substrato em uma cultura de células osteoprogenitoras, que foram obtidas por aspirado da medula óssea de suínos adultos, foram isoladas por diluição e cultivadas em placas ou no Cap com ou sem a adição de fatores de diferenciação osteogênica. As culturas foram analisadas em diferentes momentos, por 45 dias, período durante o qual se determinou a duplicação da população celular e a capacidade osteocondutora de biomaterial, através de testes bioquímicos e moleculares. Como resultado deste trabalho criou-se uma cultura primária de osteoprogenitoras da medula óssea de suínos, para avaliação in vitro de um material sintético cerâmico por reação de estado sólido, e foi explorado o potencial uso do material como um substituto para o osso natural, ao se analisar a capacidade osteocondutora, pela microscopia de luz e eletrônica e expressão de marcadores bioquímicos e moleculares, tais como a expressão de fosfatase alcalina, deposição de cálcio e acúmulo de laranja de xilenol concomitante com a detecção de Runx2, osteocalcina e osteopontin...

Analysis of Biological Apatite Orientation in Rat Mandibles / Oral Science International

Recently, significant progress has been made in medical techniques for regenerating bone. However, bone evaluation techniques generally assess bone quantity as opposed to bone quality. The use of <i>c</i>-axis crystallite orientation of biological apatite (BAp) as a bone quality index has recently generated great interest. BAp demonstrates strong crystallographic anisotropy, and preferential alignment of BAp in each bone varies depending on the shape and stress conditions <i>in vivo</i>. In the mandible, complicated bone shape and stress conditions <i>in vivo</i> might be associated with both bone quantity and quality. In this study, we aimed to elucidate changes in the bone microstructure in the mandible using crystallographic orientation of BAp as a bone quality index. Using Crj: CD (SD) IGS female rats, we observed changes in the dentulous mandible during bone growth. Measuring points on the mandible were determined based on its positional relationship with the teeth. For analysis of bone quantity, the area and bone mineral density of cortical bone were evaluated using peripheral quantitative computed tomography (pQCT), while the orientation of the BAp <i>c</i>-axis, as analyzed by a micro-beam X-ray diffraction system, was used to assess bone quality. The results of both bone quantity and quality assessments indicated that changes during bone growth varied depending on the presence of teeth. We concluded that the microstructure (especially the texture) of BAp crystallite changes in correlation with variations in stress distribution <i>in vivo</i> resulting from changes in chewing conditions designed to optimize the dynamic chewing function.

Effect of chemical treatment on the bioactivity of titanium / 대한치과보철학회지

STATEMENT OF PROBLEM: Titanium is widely used as an implant material for artificial teeth. Also, studies on surface treatment to form a fine passive film on the surface of commercial titanium or its alloys and improving bioactivity with bone have been carried out. However, there is insufficient data about the biocompatibility of the implant materials in the body. PURPOSE: The purpose of this study was to examine whether the precipitation of apatite on titanium metal is affected by surface modification. MATERIALS AND METHODS: Specimens chemically washed for 2 minute in a 1:1:1.5 (in vol%) mixture of 48% HF, 60% HNO3 and distilled water. Specimens were then chemically treated with a solution containing 97% H2SO4 and 30% H2O2 at 40 degrees C for 1 hour, and subsequently heat-treated at 400 degrees C for 1 hour. All specimens were immersed in the HBSS with pH 7.4 at 36.5 degrees C for 15 days, and the surface were examined with TF-XRD, SEM, EDX and XPS. Also, commercial purity Ti specimens with and without surface treatment were implanted in the abdominal connective tissue of mice for 4 weeks. Conventional aluminium and stainless steel 316L were also implanted for comparison. RESULTS AND CONCLUSIONS: The results obtained were summarized as follows. 1. An amorphous titania gel layer was formed on the titanium surface after the titanium specimen was treated with a H2SO4 and H2O2 solution. The average roughness was 2.175 micrometer after chemical surface treatment. 2. The amorphous titania was subsequently transformed into anatase by heat treatment at 400 degree C for 1 hour. 3. The average thickness of the fibrous capsule surrounding the specimens implanted in the connective tissue was 46.98 micrometer in chemically-treated Ti, and 52.20, 168.65 and 100.95 micrometer, respectively in commercial pure Ti, aluminum and stainless steel 316L without any treatment.

Bioactive functionally gradient material / 医疗卫生装备

This paper discusses the actuality of the artificial bioactive functionally gradient material and its developing trend.

A bone replaceable artificial bone substitute: morphological and physiochemical characterizations

A composite material consisting of carbonate apatite (CAp) and type I atelocollagen (AtCol) (88/12 in wt/wt%) was designed for use as an artificial bone substitute. CAp was synthesized at 58 degrees C by a solution-precipitation method and then heated at either 980 degrees C or 1,200 degrees C. In this study, type I AtCol was purified from bovine tail skins. A CAp-AtCol mixture was prepared by centirfugation and condensed into composite rods or disks. The scanning electron-microscopic (SEM) characterization indicated that the CAp synthesized at 58 degrees C displayed a crystallinity similar to that of natural bone and had a high porosity (mean pore size: about 3-10 microns in diameter). SEM also revealed that the CAp heated at 980 degrees C was more porous than that sintered at 1,200 degrees C, and the 1,200 degrees C-heated particles were more uniformly encapsulated by the AtCol fibers than the 980 degrees C-heated ones. A Fourier transformed-infrared spectroscopic analysis showed that the bands characteristic of carbonate ions were clearly observed in the 58 degrees C-synthesized CAp. To enhance the intramolecular cross-linking between the collagen molecules, CAp-AtCol composites were irradiated by ultraviolet (UV) ray (wave length 254 nm) for 4 hours or vacuum-dried at 150 degrees C for 2 hours. Compared to the non cross-linked composites, the UV-irradiated or dehydrothermally cross-linked composites showed significantly (p < 0.05) low collagen degradation and swelling ratio. Preliminary mechanical data demonstrated that the compressive strengths of the CAp-AtCol composites were higher than the values reported for bone.

A Clinical Study of Apatite- and Wollastonite-containing Glass-ceramics as a bone prosthesis / 대한정형외과학회잡지

PURPOSE: To investigate in vivo reaction of newly developed glass-ceramic, we inserted an iliac crest prosthesis using apatite- and wollastonite-containing glass-ceramic. The efficacy and side effect of this prosthesis, if any, were studied clinically and radiologically. MATERIALS AND METHODS: A full-thickness bone graft of the iliac crest was made in 20 patients who needed revisional surgery for THR loosening. Different sized blocks (ranging from 3 cm to 7 cm in length) of bioactive glass-ceramic prosthesis were made and implanted in a complete and large bony deficiency of the iliac crest. The postoperative follow-up period ranged from 8 to 13 months (average 11 months). Following the operations, clinical and radiological examinations were performed postoperatively at 2 weeks, 3, 6 and 12 months. RESULTS: Clinically, no foreign body reactions, including swelling and irritation, were noted. Radiologically, no displacement and no breakdown of the iliac prostheses were seen 11 months after surgery and the radiolucent line between the prosthesis and the iliac bone gradually disappeared with time in all cases. CONCLUSIONS: The apatite- and wollastonite-containing glass-ceramic supplementation for the iliac bony defect was successful experimentally and this glass-ceramic, which contains sufficient mechanical strength and can strongly bond with host bone, may be a promising prosthesis in the repair of large bone defect.

A Biomechanical Comparison of Carbonate Apatite Collagen Composite and Hydroxyapatite Implanted in Bone Defects of Rabbit Tibiae / 대한정형외과학회잡지

Autograft is frequently used to restore anatomic morphology and functional properties in bone defects. Disadvantages of the autograft are related to donor site morbidity and include the risk of wound infection, increased blood loss and additional postoperative discomfort. Allograft and xenograft, which are currently employed as the most common alternative to autografts, encounter the complications such as fracture, resorption and nonunion secondary to immunologic rejection. These volumetric and immunologic concerns with biologic implants have stimulated interest in the potential for synthetic, bioinert materials as bone graft substitutes. Hydroxyapatite (HA), a calcium phosphate ceramic, is a well known biocompatible artificial bone substitite without induction of systemic toxic and foreign body reactions. Bone conduction usually occurrs by the implanted HA but biodegradation of HA is poor and the bone formation around HA is slow. Carbonate apatite has been known as that the physicochemical properties are similar of the natural bony apatite and demonstrates no toxic reactions with better biodegradation. Carbonate apatite collagen composite was reported to show more bone formation and biodegradation than hydroxyap atite. In this study, the composite (CA-C) consisted of carbonate apatite and type I collagen was implanted in rabbit tibiae to evaluate the possibility as an artificial bone substitute. Forty HA (HA group) and forty CA-C (CA-C group) were applied in 80 dissected rabbit tibiae and fixed by external fixators. For biomechanical study, the rabbits were sacrificed and the specimens were obtained in 2, 4, 6 and 8 weeks after implantation. Tensile load was applied to the prepared tibiae in Instron and biomechanical properties were investigated. The fracture at the callus occurred as transverse or short oblique fracture in the vertical direction to the axis of applied tensile load. In each group, the tensile strength at breaking point increased significantly with time and at 4 weeks more prominent increase in break strength was observed (p<0.05). HA group showed higher mean strength before 6 weeks and at 8 weeks CA-C group higher mean strength but statistical significance could not be found. There was no significant difference in extension length at breaking point between both groups and time intervals. In summary, carbonate apatite collagen composite revealed similar biomechanical properties as hydroxyapatite, suggesting its clinical usefulness as a bone substitute, but it will be necessary to improve biodegradational property, stiffness of carbonate apatite collagen composite.

Sintering character of nanocrystal calcium-deficient apatite / 实用口腔医学杂志

Objective:To study the sintering character of calcium-deficient apatite.Methods:Calcium-deficient apatite synthesised by wet chemical method was sintered at different temperature and then its chemical composition, phase structure and morphology were examined by FT-IR spectroscopy, X-ray diffraction (XRD) and field emission scanning microscopy (FESEM) respectively.Results:When the heating temperature is below 500 ℃, apatite crystal kept a stable size with a diameter of 12-26 nm and a length of 30-66 nm. After sintered at 600 ℃ for 2 h, apatite crystal were with a diameter of 25-40 nm and a length of 75-100 nm. Around 800 ℃ for 2 h, apatite was decomposed into Ca_3(PO_4)_2.The crystal size of the Ca_3(PO_4)_2 surpassed 200 nm in diameter and length. NH_4+ ion could be removed at temperature beyond 300 ℃.Conclusion: Calcium-deficient apatite has it's specific sintering character.

A Radiological and Histological Study of Carbonate Apatite Collagen composite and Hydroxyapatite Implanted in Bone Defects of the Rabbit Tibiae / 대한정형외과학회잡지

Autograft is frequently used to restore anatomic morphology and functional properties in bone defects. Disadvantages of the autograft are related to donor site morbidity and include the risk of wound infection, increased blood loss, and additional postoperative discomfort. Allograft and xenograft, which are currently employed as the most common alternative to autografts, encounter the complications. such as fracture, resorption, and nonunion secondary to immunologic rejection. Hydroxyapatite(HAp), a calcium phosphate ceramic, is a well known biocompatible artificial bone substitute without induction of systemic toxic and foreign body reactions. Bone conduction is usually occurred by the implanted HAp. Biodegradation of HAp is poor and the bone formation around HAp is slow and about more than 70% of the natural apatite in bone is composed of carbonate apatite that has carbonic radical(CO3) instead of hydroxyl radical(OH-) or Phosphate radical(PO4 ) of HAp. Carbonate apatite ahs been known as that the physicochemical properties are similar of the natural bony apatite. In vivo experiment, carbonate apatite demonstrates non-toxic reactions. In this study, the compostite consisted of carbonate apatite and type I collagen, which is the bony structural protein, was implanted in rabbit tibiae to evaluate possibility as an artificial bone substitute. Biodegradation rate of the composite, the rate and qiantity of the regenerative cortical and cancellous bone formation were investigated radiologically and histopathologically. HAp and the carbonate apatite coilagen composite(Ap-C) were applied in the dissected rabbit tibiae(7-8mm), and fixed by external fixators. Postoperative roentgenograms were taken 2, 4, 6, and 8 weeks after implantations. For histological ohservations, the rabbits were sacrificed and the specimens were obtained 2, 4, 6, and 8 weeks after operation. Radiological Lane scores of Ap-C were 1.16±0.92, 2.16±0.98, 3.33± 0.82, and 3.67±0.51 in 2. 4, 6 and weeks after operation, while the Lane score of HAp were 0.53±0.84, 0.83±0.75, 1.67±0.81, and 2.83±0.98 respectively. Ap-C demonstrated the faster degradation and more bone formation then HAp. Though physicochemical properties of carbonate apatite is similar to those of HAp, the carbonate apatite and type I collagen composite(Ap-C) revealed rather faster degradation and bone formation than HAp in both radiological and histological investigations.