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.

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.

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.

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 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.

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.