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Introduction: Carbonated apatite (CO3Ap) has unique properties as an alloplastic bone substitute and has been reported the safety and efficacy for bone regeneration. However, no previous studies reported the clinical application of CO3Ap for periodontal regeneration therapy. The aim of this study was to evaluate the safety and efficacy of periodontal regeneration with CO3Ap in treating intrabony defects, Class II and Class III furcation involvement (FI). Methods: A single-arm and single-center prospective pilot clinical study was performed to verify the safety and efficacy of CO3Ap in patients with periodontitis. A total of four patients with seven teeth, including three deep intrabony defects, two Class II FI, and two Class III FI, were treated with CO3Ap. The clinical parameters, including probing pocket depth (PPD), clinical attachment level (CAL), bleeding on probing (BOP), tooth mobility (Mo), Plaque index (PI), and Gingival index (GI) were evaluated at baseline, 6 months, and 9 months after the surgery. Radiographic analysis was conducted on images of dental X-ray and cone beam computed tomography (CBCT) at baseline and 9 months post-surgery. Results: The postoperative healing in all cases was uneventful, with no abnormal bleeding, pain, or swelling. The mean PPD reduction and CAL gain were 5.0 ± 1.0 mm, 4.5 ± 0.7 mm, 1.5 ± 0.7 mm, and 4.7 ± 1.2 mm, 4.5 ± 0.7 mm, 0.0 mm for intrabony defect, Class II and Class III FI, respectively. According to radiographic analysis, linear bone height in intrabony defects and vertical subclassification of FI in Class II FI were improved. Conclusions: The clinical application of CO3Ap for the treatment of intrabony defects and Class II FI could be effective for periodontal regeneration, although its efficacy in treating Class III FI might be limited. Despite the limitations of this study, the findings in this study suggested that CO3Ap has the potential to be a promising bone graft substitute for periodontal regeneration.

The aim of this study is to investigate the effect of the addition of Mg ion on calcium phosphate during mechanochemical synthesis. Ca(OH)2, dicalcium phosphate dihydrate (DCPD), and Mg(OH)2 were mechanochemically synthesized using ball milling with pure water. The prepared samples were evaluated by powder X-ray diffraction analysis (XRD), FT-infrared (IR) spectral analysis, and a TNF alpha test with murine macrophage-like cell line RAW264.7 cells for assessing the immune activation. The cell culture studies indicated that CaMg apatite can be used as bioceramic. Mg ion-doped Ca apatite, which also contains carbonated ions in the crystal, was identified based on the XRD patterns and FTIR spectra. The unique diffraction peaks of apatite at 211, 112, 300, and 202 decreased in the sample containing Mg(OH)2, suggesting a decrease in the rate of crystallization. In addition, the phosphate infrared bands of the samples were different from those of the carbonated apatite. To investigate the details of the effects of Mg ion, multiple spectra combining XRD patterns and FTIR spectra were prepared. The multiple spectra datasets were used for the estimation by multivariate curve resolution-alternating least squares (MCR-ALS). The effects of Mg ion on apatite as calcium phosphate were investigated by multiple spectra multivariate analysis. The analysis postulated that Mg ion decreased the apatite crystallinities possibly by adsorption at the growth sides and that these added ions strongly inhibited the formation of the thermodynamically most stable hydroxyapatite. [ABSTRACT FROM AUTHOR]

Introduction: There has been an increasing desire for the development of predictive periodontal regenerative therapy for severe periodontitis. In this study, we investigated the effect of the combined use of fibroblast growth factor-2 (FGF-2), a drug for periodontal regeneration approved in Japan, and carbonated apatite (CO3Ap), bioresorbable and osteoconductive scaffold, on periodontal regeneration in beagle dog model of one-wall periodontal defect (severe intraosseous defect) for 24 weeks in comparison with CO3Ap or vehicle alone. Methods: One-wall periodontal defects were created (mesiodistal width × depth: 4 × 4 mm) on the mesial portion of the mandibular first molar (M1) of beagle dogs on both side. Mixture of FGF-2 and CO3Ap, vehicle and CO3Ap, or vehicle alone were administered to the defects and designated as groups FGF-2+CO3Ap, CO3Ap, and control, respectively. To assess the periodontal regeneration, radiographic analysis over time for 24 weeks, and micro computed tomography (μCT) and histological evaluation at 6 and 24 weeks were performed. Results: For the regenerated tissue in the defect site, the mineral content of the FGF-2+CO3Ap group was higher than that of the CO3Ap group in the radiographic analysis at 6–24 weeks. In the context of new bone formation and replacement, the FGF-2+CO3Ap group exhibited significantly greater new bone volume and smaller CO3Ap volume than the CO3Ap group in the μCT analysis at 6 and 24 weeks. Furthermore, the density of the new bone in the FGF-2+CO3Ap group at 24 weeks was similar to those in the control and CO3Ap groups. Histological evaluation revealed that the length of the new periodontal ligament and cementum in the FGF-2+CO3Ap group was greater than that in the CO3Ap group at 6 weeks. We also examined the effect of the combined use of the FGF-2 and CO3Ap on the existing bone adjacent to the defect and demonstrated that the existing bone height and volume in the FGF-2+CO3Ap group remained significantly greater than those in the CO3Ap group. Conclusion: This study demonstrated that the combination of FGF-2 and CO3Ap was effective not only in enhancing new bone formation and replacing scaffold but also in maintaining the existing bone adjacent to the defect site in a beagle dog model of one-wall periodontal defect. Additionally, new periodontal tissues induced by FGF-2 and CO3Ap may follow a maturation process similar to that formed by spontaneous healing. This suggests that the combined use of FGF-2 and CO3Ap would promote periodontal regeneration in severe bony defects of periodontitis patient.

The environment model for the description of the location of carbonate ions in apatites predicts that approximately half of the carbonate occupies the apatite channel. This model relies on the influence of entities surrounding the carbonate on its IR spectrum and can be used to determine how various substituents affect the location and structure of that ion. Careful deconvolution (peak-fitting) of the asymmetric carbonate IR region was used to determine the percentage of A-type (channel) ions, A′-type (channel with either a Ca2+ vacancy or substitution of Na+ for Ca2+) ions, and B-type (substitution for phosphate) ions. In our previous applications of this model, we have looked at the effect of alkali metal ions, such as sodium, lithium, and potassium, the ammonium ion, and the rare earth europium ion. In the present work, we explore the incorporation of the first-row transition metal ions and find that they have little effect on the location of the carbonate ion. Like the un-substituted carbonated apatite, these apatites contain about half of the carbonate in the channel, at least in derivatives that contain up to half a mole of the metal ion per mole of apatite. Attempts to incorporate greater amounts of metal ions by aqueous ion-combination reactions generally lead to lower-resolution XRD patterns and IR spectra that produce greater uncertainties in the peak-fitting modeling. [ABSTRACT FROM AUTHOR]

Introduction: Currently, flap operation (FOP) using REGROTH® (0.3% basic fibroblast growth factor [FGF-2]) is the standard treatment for periodontal regenerative therapy in Japan. However, the periodontal tissue regenerative effect with REGROTH® monotherapy is inadequate for severe alveolar bone defects. Therefore, in this study, we evaluated the safety and effectiveness of periodontal regenerative therapy for patients with severe periodontitis using REGROTH® (test medicine) combined with Cytrans® Granules (test device: carbonated apatite granules), which is a new artificial bone. Methods: The study participants included 10 patients with severe periodontitis (mean age: 47.4 years). All participants provided written informed consents. In each patient, the intrabony defect site (mean bone defect depth: 5.7 mm) was defined as the test site. FOP was performed for the test site after the baseline investigation; moreover, the test medicine and test device were administered simultaneously. Furthermore, the observation of subjects’ general condition and test sites was conducted and the blood, urine, and periodontal tissue tests were performed up to 36 weeks after FOP. The rate of bone increase (%), clinical attachment level (CAL), probing pocket depth (PPD), bleeding on probing (BOP), tooth mobility (Mo), width of keratinized gingiva (KG), gingival recession (REC), gingival index (GI), and plaque index (PlI) were evaluated during the periodontal tissue investigation. Results: As the primary endpoint, no adverse events related to the test medicine and test device occurred during the entire observation period of this study. Regarding the secondary endpoints, there was a significant increase in new alveolar bone (p = 0.003) and CAL acquisition (p = 0.001) as well as decrease in PPD (p = 0.002) and BOP (p = 0.016) at 36 weeks after administration of the test medicine and test device compared with the preoperative values. Furthermore, at 36 weeks after surgery, the Mo, GI, and PlI decreased to preoperative levels at 40%, 60%, and 30% of sites, respectively. However, at 36 weeks after surgery, there was no difference in KG and REC compared with their preoperative values. Conclusions: The safety of periodontal regenerative therapy using the test medicine in combination with the abovementioned test device was confirmed. In addition, it was suggested that this periodontal regenerative therapy is effective for tissue regeneration in severe alveolar bone defects.This clinical trial was conducted after registering and publicizing as a specified clinical trial in the Japan registry of clinical trials (jRCTs051190045).

Composites of synthetic bone mineral substitutes (BMS) and biodegradable polyesters are of particular interest for bone surgery and orthopedics. Manufacturing of composite scaffolds commonly uses mixing of the BMS with polymer melts. Melt processing requires a high homogeneity of the mixing, and is complicated by BMS-promoted thermal degradation of polymers. In our work, poly(L-lactide) (PLLA) and poly(ε-caprolactone) (PCL) composites reinforced by commercial β-tricalcium phosphate (βTCP) or synthesized carbonated hydroxyapatite with hexagonal and plate-like crystallite shapes (hCAp and pCAp, respectively) were fabricated using injection molding. pCAp-based composites showed advanced mechanical and thermal characteristics, and the best set of mechanical characteristics was observed for the PLLA-based composite containing 25 wt% of pCAp. To achieve compatibility of polyesters and pCAp, reactive block copolymers of PLLA or PCL with poly(tert-butyl ethylene phosphate) (C1 and C2, respectively) were introduced to the composite. The formation of a polyester-b-poly(ethylene phosphoric acid) (PEPA) compatibilizer during composite preparation, followed by chemical binding of PEPA with pCAp, have been proved experimentally. The presence of 5 wt% of the compatibilizer provided deeper homogenization of the composite, resulting in a marked increase in strength and moduli as well as a more pronounced nucleation effect during isothermal crystallization. The use of C1 increased the thermal stability of the PLLA-based composite, containing 25 wt% of pCAp. In view of positive impacts of polyester-b-PEPA on composite homogeneity, mechanical characteristics, and thermal stability, polyester-b-PEPA will find application in the further development of composite materials for bone surgery and orthopedics. [ABSTRACT FROM AUTHOR]

Raman spectroscopy is widely used to examine the carbonate content within bone apatite, but Raman spectra are also sensitive to orientation effects between the polarisation of the incoming laser light and the sample orientation. This may lead to discrepancies when using Raman spectroscopy to evaluate the carbonate content as the extent of crystal organisation can change depending on the type of bone, age, and presence of mineralisation disorders in the organism. It is experimentally very challenging to evaluate the effect of orientation using individual bone crystals. Therefore, we have used density functional theory to examine the effect of orientation in apatitic materials. We examined hydroxyapatite and three different types of carbonated apatite: A‐type where the carbonate ion substitutes the two OH groups in the unit cell, B‐type where co‐substitution occurs between carbonate in a phosphate position and Na+ for Ca2+ to maintain charge balance, and AB‐type where carbonate sits in both A‐site and B‐site. Our simulations show that the OH group in hydroxyapatite has a strong orientation dependence, consistent with previous literature. In addition, the phosphate and carbonate bands of the apatitic structures are predicted to be orientation dependent, where the maximum scattering efficiency occurs in configurations in which the laser polarisation is parallel to the crystallographic axes of the material. The intensity changes of the phosphate and carbonate bands are not consistent upon changing orientations and thus may lead to an underestimation of carbonate contents if insufficient sampling points are used during bone analysis. [ABSTRACT FROM AUTHOR]

The present investigation exposes the main results raised from an active collaboration started in 2018 with the San Pio Hospital (Benevento, Southern Italy), aiming at a detailed mineralogical investigation of urinary stones of patients from the Campania region. Forty-nine uroliths (both bladder and kidney stones) have been surgically collected from patients admitted between 2018 and 2020 at the Department of Urology of the San Pio Hospital and characterized for clinical purposes and environmental biomonitoring from a mineralogical point of view. Possible causes and environmental implications were inferred according to the morpho-constitutional classification of the uroliths carried out by means of a conventional analytical approach. The mineralogical frequency distribution of uroliths from the Campanian region can be discussed as a function of dietary, socio-demographic, and environmental risk factors. Whewellite [CaC2O4·H2O] and weddellite [CaC2O4·(2+x)H2O], along with anhydrous calcium oxalate, represent the main mineralogical phases forming the biominerals examined here. Worth to note is that the percentage of oxalates in the Campanian region (ca. 51%) is quite comparable to those of other Mediterranean areas. Frequent uricite [C5H4N4O3] (ca. 33%), mainly observed in bladder stones of older male patients, could be related to an incorrect lifestyle and dietary habits. Occurrence of lower percentages of phosphate (i.e., brushite [CaHPO4·2(H2O)] and carbonated apatite [Ca10(PO4CO3)6(OH)8]) and mixed stones (such as, for example, a mixture of ammonium urate [NH4C5H3N4O3] and calcium oxalates) indicates specific etiopathogenetic mechanisms, suggesting proper therapeutical approaches. [ABSTRACT FROM AUTHOR]

• For the first time, copolymers of l -lactide and l -methylglycolide were synthesized. • l -Methylglycolide (l -MeGL)-based PLGAs are highly randomized. • Higher thermal and hydrolytic stability of l -MeGL-based PLGAs vs. PLGA 85/15. • Composites of l -MeGL-based PLGAs and carbonated apatite were prepared and studied. Poly(lactic- co -glycolic acid)s (PLGAs) hold considerable significance for their biomedical applications. Biodegradation and mechanical properties of PLGAs and PLGA-based composites are strongly influenced by lactate/glycolate (L/G) ratio in copolymers, molecular weight characteristics and microstructure of PLGAs. The common approach to PLGAs is based on ring-opening copolymerization of lactides and glycolide, the products of which contain long (L) n and (G) n segments. An efficient but expensive approach to PLGAs with given l -G sequences is a segmer assembly polymerization that is hardly applicable for the synthesis of high-MW PLGAs. In the present work, for the first time we synthesized lactate-enriched PLGAs using ring-opening copolymerization of l -lactide (l -LA) with l -methylglycolide (l -MeGL) in 85:15 and 70:30 molar ratios, resulting in l -PLMG 85/15 and l -PLMG 70/30 copolymers. l -PLGA 85/15 with the same L/G ratio as in PLMG 70/30 was synthesized by ring-opening copolymerization of l -LA with glycolide as a sample for a comparison. According to 1H and 13C NMR data and [α] D measurements, l -MeGL-based PLGAs had a unique microstructure, e.g. macromolecules of l -PLMG 85/15 consisted of L n sequences with single G insertions. Composites of PLLA and three samples of PLGAs with plate-like carbonated apatite (pCAp) containing 25 and 50 wt.% of the filler were prepared. Rectangular specimens from (co)polymers and (co)polymer composites were obtained by injection molding and studied. Due to the absence of highly reactive (G) n fragments, l -PLMG 85/15 and PLMG 70/30-based materials demonstrated higher thermal and hydrolytic stability, mechanical testing showed that l -MeGL-based copolymers provide better maintaining of the bending strength in comparison with l -PLGA 85/15 matrix. [Display omitted] [ABSTRACT FROM AUTHOR]

Bone-like materials comprise carbonated-hydroxyapatite nanocrystals (c-Ap) embedding a fibrillar collagen matrix. The mineral particles stiffen the nanocomposite by tight attachment to the protein fibrils creating a high strength and toughness material. The nanometer dimensions of c-Ap crystals make it very challenging to measure their mechanical properties. Mineral in bony tissues such as dentine contains 2~6 wt.% carbonate with possibly different elastic properties as compared with crystalline hydroxyapatite. Here we determine strain in biogenic apatite nanocrystals by directly measuring atomic deformation in pig dentine before and after removing carbonate. Transmission electron microscopy revealed the platy 3D morphology while atom probe tomography revealed carbon inside the calcium rich domains. High-energy X-ray diffraction in combination with in situ hydrostatic pressurization quantified reversible c-Ap deformations. Crystal strains differed between annealed and ashed (decarbonated) samples, following 1 or 10 h heating at 250 °C or 550 °C respectively. Measured bulk moduli (K) and a- / c- lattice deformation ratios (η) were used to generate synthetic K syn and η syn identifying the most likely elastic constants C 33 and C 13 for c-Ap. These were then used to calculate the nanoparticle elastic moduli. For ashed samples, we find an average E 11 =107 GPa and E 33 =128 GPa corresponding to ~5% and ~17% stiffening of the a-/c- axes of the nanocrystals as compared with the biogenic nanocrystals in annealed samples. Ashed samples exhibit ~10% lower Poisson's ratios as compared with the 0.25~0.36 range of carbonated apatite. Carbonate in c-Ap may therefore serve for tuning local deformability within bony tissues. Carbonated apatite nanoparticles, typical for bony tissues, stiffen the network of collagen fibrils. However, it is not known if the biogenic apatite mechanical (elastic) properties differ from those of geologic mineral counterparts. Indeed the tiny dimensions and variable carbonate composition may have strong effects on deformation resistance. The present study provides experimental measurements of the elastic constants which we use to estimate Young's moduli and Poisson's ratio values. Comparison between ashed and annealed dentine samples quantifies the properties of both carbonated and decarbonated apatite nanocrystals. The results reveal fundamental attributes of bony mineral and showcase the additive advantages of combining X-ray diffraction with in situ hydrostatic compression, backed by atom probe and transmission electron microscopy tomography. Image, graphical abstract [ABSTRACT FROM AUTHOR]

A new model for the location and distribution of carbonate ions in carbonated apatite was used to assign the IR spectra of A- and AB-carbonated apatites. The percentage of total carbonate as measured by the mass loss in the TGA of these compounds is in good agreement with the percentage obtained by combustion analysis. The decomposition of pure A-type carbonate appears at temperatures of 985–1123 °C, whereas the decomposition of AB-type carbonated apatites occurs in the range of 600–800 °C. This difference is attributed to changes in the environment of channel carbonate brought about by B-type substitution of carbonate for phosphate. In the presence of sodium ions, the channel is changed by substitution of sodium for calcium in order to accommodate the difference between the charge of the carbonate and phosphate ions. A thermodynamic cycle is introduced to rationalize the differences in decomposition temperatures of A- and B-type carbonate. Preferential loss of B-type carbonate upon heating to 600 °C also suggests the migration of B-type carbonate to A-sites. [ABSTRACT FROM AUTHOR]

Clumped isotope data from carbonated apatite from in vivo and in vitro samples are presented to refine the relationship between mineral growth temperature and carbonate clumped isotopic composition (Δ 47). Δ 47 , δ18O and δ13C data were obtained from phosphoric acid digestion (T = 110 °C) of chemically untreated teeth from an African elephant, Greenland sharks, sand tiger sharks and synthetic apatites. These data cover a temperature range between 1 °C and 80 °C and enlarge the calibration dataset presented in Wacker et al. (2016) by a factor of five. Taxon-specific analyses of tooth enamel(oid) and dentine reveal that both tissues show identical Δ 47 values even though the content of organic matter differs by an order of magnitude. The following Δ 47 temperature calibration for (bio)apatite is derived (R2 = 0.9924, p -value < 0.0001, n = 122; 8 samples): Δ 47 C D E S 110 = 0.0325 (± 0.0012) × 10 6 / T 2 + 0.2137 (± 0.0124) (w i t h T i n K a n d Δ 47 i n ‰) This calibration becomes indistinguishable from a reprocessed empirical calibration of calcite made in the same laboratory if a difference of the acid fractionation factors (AFF) of 0.110‰ between 25 °C and 110 °C is considered. The measured AFF for bioapatite matches the one that is extrapolated from experimental data on calcite and aragonite. The oxygen isotope fractionation between structural carbonate in the synthesized carbonated hydroxylapatites (CHAP) and water between 7 °C and 80 °C closely follows the temperature dependence for the calcite-water system. It is described by the following (CHAP-water) equation (R2 = 0.997, p -value < 0.04, n = 17; 3 samples): 1000 l n (α C H A P - w a t e r) = 17.23 ± 0.59 × 10 3 × T - 1 - 27.28 (± 1.73) (w i t h T i n K) Both calibrations are applied to shark teeth from a modern Greenland shark and a fossil megatooth shark (Carcharodon megalodon) specimen to reconstruct the apparent Δ 47 -based habitat temperature of C. megalodon (19 ± 4 °C) and the oxygen isotopic compositions of seawater. [ABSTRACT FROM AUTHOR]

Context: Biomineralization is a process which leads to the formation of an interfacial layer with tag-like structures at the cement-dentin interface. It is due to interaction of mineral trioxide aggregate (MTA) and Portland cement with dentin in phosphate-buffered solution (PBS). This study is aimed to evaluate the effect of influence of biomineralization process on push-out bond strength of ProRoot MTA (Dentsply Tulsa Dental, Tulsa, OK, USA), MTA Branco (Angelus Soluc¸o˜es Odontolo´gicas, Londrina, PR, Brazil) and calcium phosphate cement (BioGraft CPC). Aim: The aim of this study was to evaluate the effect of biomineralization process on the push-out strength of ProRoot MTA, MTA Branco, and CPC after mixing with 0.2% chlorhexidine gluconate solution (0.2% CHX) and 2% lidocaine solution (2% LA) on the bond strength of MTA-dentin. Materials and Methods: Dentin discs with uniform cavities were restored with ProRoot MTA, MTA Branco, and calcium phosphate cement after mixing with 0.2% CHX solution and 2% lidocaine solution. The samples were uniformly distributed into two groups. Experimental group being immersed in PBS solution and control group being immersed in saline for 2 months. Instron testing machine (Model 4444; Instron Corp., Canton, MA, USA) was used to determine the bond strength. Statistical Analysis Used: A two-way analysis of variance and post hoc analysis by Bonferroni test. Results: All samples immersed in experimental group displayed a significantly greater resistance to displacement than that observed for the samples in control group (P < 0.05). MTAs displayed a significantly greater resistance to displacement than calcium phosphate cements. Conclusion: The main conclusion of this study was that the push-out bond strength of the cements, mainly the MTA groups, was positively influenced by the biomineralization process.

Carbonated hydroxyapatites (CAp) are very close to natural bone apatite in chemical composition and are regarded as a prospective bone mineral substitute for bone surgery and orthopedics. However, until now, the studies and applications of CAp were limited because of the amorphous nature of the synthetic CAp. In the present work, microsized highly crystalline carbonated apatites with uniform hexagonal (hCAp) or platelike (pCAp) morphology have been studied for the first time in vitro and in vivo, comparing against commercial hydroxyapatite (HAp) and β-tricalcuim phosphate (βTCP). In vitro experiments on dissolution of those calcium phosphate ceramics (CPCs) in acetate (pH 5.5) and Tris (pH 7.3) buffer solutions showed the following rank order of the dissolution rates: βTCP > hCAp > pCAp > HAp. The higher dissolution rate of hCAp in comparison with pCAp is explained by chemical anisotropy of the crystallite surfaces, which was proven by SEM studies of the changes in the morphology of hCAp and pCAp crystallites during hydrolysis. A 5-week experiment on subcutaneous implantation of CPC species showed the following rank order of bioresorption rates: βTCP > pCAp > hCAp > HAp. pCAp matrixes exhibited the highest biocompatibility, confirmed by histomorphological analysis. Three-month bone regeneration experiments involving a rat tibial defect model were conducted with 250-500 μm granules of pCAp and pCAp-PEPA [pCAp, pretreated with 2 wt % poly(ethylene phosphoric acid)]. Notably, pCAp-PEPA implants were resorbed at higher rates and induced the formation of more mature osseous tissue, a compact bone with Haversian systems.

Various carbonated calcium phosphate powders were synthesized by aqueous precipitation and ceramics consolidation by spark plasma sintering (SPS) at very low temperature was investigated. The objective was to preserve low crystallinity and avoid material decarbonation. SPS at low temperature only leads to little or no sintering when crystallized powders are used. Amorphous powders are required. In this case, consolidation occurs at temperatures below 150 °C. It is accompanied by crystallization of the amorphous phase into calcium-deficient carbonated apatite Ca 10-x-y (PO 4 ) 6-x-y (HPO 4 ) x (CO 3 ) y (OH) 2-x-y-2z (CO 3 ) z . The resulting ceramics are microporous and highly cohesive with good mechanical properties (flexural strength = 18 MPa). The sintering mechanism, called “crystal fusion”, is based on solid state diffusion of chemical species at the grain boundary and crystal growth within the amorphous particles. These bioceramics that mimic the composition of the bone mineral are expected to have a higher bioreactivity than well crystallized carbonated hydroxyapatite ceramics obtained by conventional sintering. [ABSTRACT FROM AUTHOR]

A series of B-type carbonated apatites with varying carbonate levels were synthesized in order to analyze how synthetic materials and natural bone structure change with carbonate contents. FT-IR, Raman spectroscopy, and X-ray diffraction have been employed as combined tools to study the structural change of synthetic carbonated apatite and nature bone mineral. B-type carbonated apatites have been extensively investigated because they resemble most closely of mineral phase of nature bone. In this study, we found that hydroxyl ions in the apatite lattice are reduced as the carbonate contents increase. These results demonstrate that the substitution of tetrahedron phosphate ions by planar carbonate ions causes the structural deficiency of hydroxyl ions. [ABSTRACT FROM AUTHOR]

The mineral component of bone and other biological calcifications is primarily a carbonate substituted calcium apatite. Integration of carbonate into two sites, substitution for phosphate (B-type carbonate) and substitution for hydroxide (A-type carbonate), influences the crystal properties which relate to the functional properties of bone. In the present work, a series of AB-type carbonated apatites (AB-CAp) having varying A-type and B-type carbonate weight fractions were prepared and analyzed by Fourier transform infrared spectroscopy (FTIR), powder X-ray diffraction (XRD), and carbonate analysis. A detailed characterization of A-site and B-site carbonate assignment in the FTIR ν 3 region is proposed. The mass fractions of carbonate in A-site and B-site of AB-CAp correlate differently with crystal axis length and crystallite domain size. In this series of samples reduction in crystal domain size correlates only with A-type carbonate which indicates that carbonate in the A-site is more disruptive to the apatite structure than carbonate in the B-site. High temperature methods were required to produce significant A-type carbonation of apatite, indicating a higher energy barrier for the formation of A-type carbonate than for B-type carbonate. This is consistent with the dominance of B-type carbonate substitution in low temperature synthetic and biological apatites. [ABSTRACT FROM AUTHOR]

Context: Biomineralization is a process which leads to the formation of an interfacial layer with tag-like structures at the cement-dentin interface. It is due to interaction of mineral trioxide aggregate (MTA) and Portland cement with dentin in phosphate-buffered solution (PBS). This study is aimed to evaluate the effect of influence of biomineralization process on push-out bond strength of ProRoot MTA (Dentsply Tulsa Dental, Tulsa, OK, USA), MTA Branco (Angelus Soluc,ões Odontolo 'gicas, Londrina, PR, Brazil) and calcium phosphate cement (BioGraft CPC). Aim: The aim of this study was to evaluate the effect of biomineralization process on the push-out strength of ProRoot MTA, MTA Branco, and CPC after mixing with 0.2% chlorhexidine gluconate solution (0.2% CHX) and 2% lidocaine solution (2% LA) on the bond strength of MTA-dentin. Materials and Methods: Dentin discs with uniform cavities were restored with ProRoot MTA, MTA Branco, and calcium phosphate cement after mixing with 0.2% CHX solution and 2% lidocaine solution. The samples were uniformly distributed into two groups. Experimental group being immersed in PBS solution and control group being immersed in saline for 2 months. Instron testing machine (Model 4444; Instron Corp., Canton, MA, USA) was used to determine the bond strength. Statistical Analysis Used: A two-way analysis of variance and post hoc analysis by Bonferroni test. Results: All samples immersed in experimental group displayed a significantly greater resistance to displacement than that observed for the samples in control group (P < 0.05). MTAs displayed a significantly greater resistance to displacement than calcium phosphate cements. Conclusion: The main conclusion of this study was that the push-out bond strength of the cements, mainly the MTA groups, was positively influenced by the biomineralization process. [ABSTRACT FROM AUTHOR]

Magnesium alloys are promising candidates for load-bearing orthopedic implants due to their biodegradability and mechanical resemblance to natural bone tissue. However, the high degradation rate and the risk of implant-associated infections pose grand challenges for their clinical applications. Herein, we developed a nano-multilayered coating strategy through polydopamine and chitosan assisted layer-by-layer assembly of osteoinductive carbonated apatite and antibacterial sliver nanoparticles on the surface of AZ31 magnesium alloys. The fabricated nano-multilayered coating can not only obviously enhance the corrosion resistance but also significantly increase the antibacterial activity and demonstrate better biocompatility of magnesium alloys. [ABSTRACT FROM AUTHOR]

This paper focuses on the fabrication of three-dimensional porous PLGA-biomimetic carbonated apatite composite scaffolds by freeze-casting and using dimethyl carbonate as a solvent. Several charge/polymer ratios were tested in order to finely understand the influence of the filler rate on the scaffold porosity and mechanical and degradation properties using complementary characterization techniques (SEM, mercury porosimetry and X-ray microtomography). It was demonstrated that the apatite ratio within the composite scaffold has a strong influence in terms of architecture, material cohesion, mechanical properties and in vitro degradation properties. An optimum biomimetic apatite ratio was reached to combine good mechanical properties (higher rigidity) and material cohesion. In vitro degradation studies showed that higher apatite filler rates limited PLGA degradation and enhanced the hydrophilicity of the scaffolds which is expected to improve the biological properties of the scaffolds in addition to the bioactivity related to the presence of the apatite analogous to bone mineral. [ABSTRACT FROM AUTHOR]

The sorption of selenite, SeO 3 2− , by carbonate substituted hydroxylapatite was investigated using batch kinetic and equilibrium experiments. The carbonate substituted hydroxylapatite was prepared by a precipitation method and characterized by SEM, XRD, FT-IR, TGA, BET and solubility measurements. The material is poorly crystalline, contains approximately 9.4% carbonate by weight and has a surface area of 210.2 m 2 /g. Uptake of selenite by the carbonated hydroxylapatite was approximately an order of magnitude higher than the uptake by uncarbonated hydroxylapatite reported in the literature. Distribution coefficients, K d , determined for the carbonated apatite in this work ranged from approximately 4200 to over 14,000 L/kg. A comparison of the results from kinetic experiments performed in this work and literature kinetic data indicates the carbonated apatite synthesized in this study sorbed selenite 23 times faster than uncarbonated hydroxylapatite based on values normalized to the surface area of each material. The results indicate carbonated apatite is a potential candidate for use as a sorbent for pump-and-treat technologies, soil amendments or for use in permeable reactive barriers for the remediation of selenium contaminated sediments and groundwaters. [ABSTRACT FROM AUTHOR]

A combined experimental and computational approach was employed to investigate the feasibility and effectiveness of characterizing carbonated apatite (CAp) by infrared (IR) spectroscopy. First, an experimental comparative study was conducted to identify characteristic IR vibrational bands of carbonate substitution in the apatite lattice. The IR spectra of pure hydroxyapatite (HA), carbonate adsorbed on the HA surface, a physical mixture of HA and sodium carbonate monohydrate, a physical mixture of HA and calcite, synthetic CAps prepared using three methods (precipitation method, hydrothermal route, and solid‐gas reaction at high temperature) and biological apatites (human enamel, human cortical bone, and two animal bones) were compared. Then, the IR vibrational bands of carbonate in CAp were calculated with density functional theory. The experimental study identified characteristic IR bands of carbonate that cannot be generated from surface adsorption or physical mixtures and the results show that the bands at ∼880, 1413, and 1450 cm−1 should not be used as characteristic bands of CAp since they could result from carbonate adsorbed on the apatite crystals surface or present as a separate phase. The combined experimental and computational study reveals that the carbonate v3 bands at ∼1546 and 1465 cm−1 are, respectively, the IR signature bands for type A CAp and type B CAp. [ABSTRACT FROM AUTHOR]

Highlights: [•] One-step synthesis of hydroxyapatite (Ca-HA) from CaCO3 and H3PO4. [•] Reactivity of Ca-HA in lead(II) removal from an aqueous solution. [•] Ca-HA particles in gel form more active compared to dried Ca-HA powder. [•] Fixation of lead on the external surface and in pores of Ca-HA particles. [•] Beneficial effect of carbonate ions inserted in apatitic structure on metal fixation. [ABSTRACT FROM AUTHOR]

Abstract: Solid-state (magic-angle spinning) NMR spectroscopy is a useful tool for obtaining structural information on bone organic and mineral components and synthetic model minerals at the atomic-level. Raman and 31P NMR spectral parameters were investigated in a series of synthetic B-type carbonated apatites (CAps). Inverse 31P NMR linewidth and inverse Raman PO4 3− ν 1 bandwidth were both correlated with powder XRD c-axis crystallinity over the 0.3–10.3wt% CO3 2− range investigated. Comparison with bone powder crystallinities showed agreement with values predicted by NMR and Raman calibration curves. Carbonate content was divided into two domains by the 31P NMR chemical shift frequency and the Raman phosphate ν 1 band position. These parameters remain stable except for an abrupt transition at 6.5wt% carbonate, a composition which corresponds to an average of one carbonate per unit cell. This near-binary distribution of spectroscopic properties was also found in AFM-measured particle sizes and Ca/P molar ratios by elemental analysis. We propose that this transition differentiates between two charge-balancing ion-loss mechanisms as measured by Ca/P ratios. These results define a criterion for spectroscopic characterization of B-type carbonate substitution in apatitic minerals. [Copyright &y& Elsevier]

Abstract: Ab initio quantum mechanical (QM) calculations were employed to study the crystal structure and elastic properties of carbonated apatite (CAp). Two locations for the carbonate ion in the apatite lattice were considered: carbonate substituting for OH− ion (type-A), and for PO4 3− ion (type-B) with possible charge compensation mechanisms. A combined type-AB substitution (two carbonate ions replacing one phosphate group and one hydroxyl group, respectively) was also investigated. The results show that the most energetically stable substitution is type-AB, followed by type-A and then type-B. The most stable configuration of type-A has its carbonate triangular plane almost parallel to c-axis at z=0.46. The lowest energy configuration of type-B is that with a sodium ion substituting for a calcium ion for charge balance and the carbonate lying on the b/c-plane of apatite. Lattice parameter changes after carbonate substitution in hydroxyapatite (HA) agree with reported experimental results qualitatively: for type-A, lattice parameter a increases but c decreases; and for type-B, lattice parameter a decreases but c increases. Using the calculated CAp stable structures, we also calculated the elastic properties of CAp and compared them with those of HA and biological apatites. [Copyright &y& Elsevier]

Abstract: Biomimetic synthesis of carbonated apatites with good biocompatibility is a promising strategy for the broadening application of apatites for bone tissue engineering. Most researchers were interested in collagen or gelatin-based templates for synthesis of apatite minerals. Inspired by recent findings about the important role of polysaccharides in bone biomineralization, here we reported that heparin, a mucopolysaccharide, was used to synthesize carbonated apatites in vitro. The results indicated that the Ca/P ratio, carbon content, crystallinity and morphology of the apatites varied depending on the heparin concentration and the initial pH value. The morphology of apatite changed from flake-shaped to needle-shaped, and the degree of crystallinity decreased with the increasing of heparin concentration. Biocompatibility of the apatites was tested by proliferation and alkaline phosphatase activity of MC3T3-E1 cells. The results suggested that carbonated apatites synthesized in the presence of heparin were more favorable to the proliferation and differentiation of MC3T3-E1 cells compared with traditional method. In summary, the heparin concentration and the initial pH value play a key role in the chemical constitution and morphology, as well as biological properties of apatites. These biocompatible nano-apatite crystals hold great potential to be applied as bioactive materials for bone tissue engineering. [Copyright &y& Elsevier]

Potential use of hydroxyapatite nanoparticles (HANPs) [Ca 10 (PO 4 ) 6 (OH) 2 ] as slow P-release fertilizer (SRF) has recently attracted wider attention. However, commercially available HANP (with Ca/P ratio = 1.667) is the least soluble calcium phosphate and thus limits its full potential as an SRF in agronomic applications. In this research, we sought to enhance the dissolution rate of HANPs by enriching hydrogen phosphate (HPO 4 2- ) species in the phosphate (PO 4 3- ) structural sites. Seven different types of pure crystalline HANPs were synthesized at a range of Ca/P ratio from 1.46 (at pH 6.0) to 2.10 (at pH 12.0). Complementary results from FTIR and solid-state 31 P MAS NMR spectroscopies showed that HPO 4 2- species is most abundant in HANPs crystallized at pH 6.0 and gradually depleted at higher pH products. The rate of depletion of HPO 4 2- species is proportional to the increase in carbonate incorporation into the HANP lattice, which preferentially forms B-type carbonated HANPs. The enhanced dissolution rate of HANPs due to hydrogen phosphate incorporation was tested using a flow-through macro-dialysis system that limits the partial transition of HANPs to other solid phases, which otherwise interfere with dissolution. The results show that the dissolution rate of HANPs increased with decreasing pH of synthesis and was highest in HANPs at pH 6.0. The dissolution rate differed by ten times between HANPs synthesized at pH 7.0 and 10.0. Overall, the atom-efficient synthetic route developed and the ability to tune the dissolution rate of HANPs are significant steps forward in improving the P-release efficiency of a potent SRF and is expected to contribute to efforts toward enhancing agricultural sustainability., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022. Published by Elsevier B.V.)

Abstract: Introduction: Capasio is being developed as a new generation of endodontic material with potential use as a root-end filling material. The aim of this study was to compare the ability of Capasio and mineral trioxide aggregate (MTA) to penetrate human dentinal tubules and examine the interaction of Capasio and MTA with a synthetic tissue fluid (STF) and root canal walls in extracted human teeth. Methods: Root-end preparations were filled with Capasio or MTA, allowed to set for 4 weeks in STF, and then sectioned at 1, 2, and 3 mm from resected surface. Depth of penetration was evaluated by using scanning electron microscopy (SEM). Next, Capasio and MTA samples were prepared both in 1-g pellets and in root-end preparations. Samples were placed in STF, allowed to set, and then characterized by using SEM, energy dispersive x-ray analysis (EDXA), and x-ray diffraction (XRD) techniques. Results: Penetration of Capasio into dentinal tubules was observed at all levels. No penetration of MTA into dentinal tubules was observed at any level. Both Capasio and MTA formed apatite crystals in the supernatant, on their exposed surfaces, and in the interfacial layers that were similar in structure and elemental composition when evaluated by using SEM and EDXA. XRD analysis of these crystals corresponds with those reported for hydroxyapatite. Conclusions: When used as a root-end filling material, Capasio is more likely to penetrate dentinal tubules. Both Capasio and MTA promote apatite deposition when exposed to STF. [Copyright &y& Elsevier]

The purpose of this study was to develop a simple and quick method of evaluating the physicochemical properties of carbonated apatite preparations (CAP) as an index of the bioaffinity of implantable materials based on Fourier-transformed-infrared (IR) spectra by chemometrics. The wet-synthesized CAPs contained various levels of carbonate content (CO3), and were analyzed microstrain parameter (MS), crystallite size parameter (CP), specific surface area (Sw), CO3, and solubility parameter (p KHAP) using by X-ray powder diffraction, nitrogen gas adsorption, IR, and UV absorption. The IR spectral results of CAPs suggested that the peak intensities of CAP reflected the physicochemical properties of the samples. The IR data sets were calculated to obtain calibration models evaluating the physicochemical properties of CAPs by a partial least squares regression analysis (PLS). As validation of the calibration model, physicochemical properties of CAP could be evaluated based on validation IR data sets of independent samples, and those values had sufficient accuracy. The regression vector of each calibration model suggested that the physicochemical properties of CAP, such as CO3, Sw, MS, CP, and p KHAP, were affected by phosphate, hydroxyl, and carbonate groups. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2012. [ABSTRACT FROM AUTHOR]

Abstract: Introduction: Mineral trioxide aggregate (MTA) and Portland cement have been shown to be bioactive because of their ability to produce biologically compatible carbonated apatite. This study analyzed the interaction of MTA and white Portland cement with dentin in vivo. Methods: Seventy-two human dentin tubes were filled with MTA Branco, MTA BIO, and white Portland cement + 20% bismuth oxide (PC1) or PC1 + 10% of calcium chloride (PC2) and implanted subcutaneously in 18 rats at 4 sites from the dorsal area. Empty dentin tubes, implanted in rats of a pilot study, were used as control. After 30, 60, and 90 days, the animals were killed, and the dentin tubes were retrieved for scanning electron microscope analysis. Results: In the periods of 30 and 60 days, the mineral deposition in the material-dentin interface (interfacial layer) and in the interior of dentinal tubules was detected in more tubes filled with MTA Branco and MTA BIO than in tubes filled with PC1 and PC2. After 90 days, the interfacial layer and intratubular mineralization were detected in all tubes except for 3 and 1 of the tubes filled with PC2, respectively. Conclusions: It was concluded that all the cements tested were bioactive. The cements released some of their components in the tissue capable of stimulating mineral deposition in the cement-dentin interface and in the interior of the dentinal tubules. MTA BIO and MTA Branco were more effective in promoting the biomineralization process than Portland cements, mainly after 30 and 60 days. [Copyright &y& Elsevier]

Danesh F, Vahid A, Jahanbani J, Mashhadiabbas F, Arman E. Effect of white mineral trioxide aggregate compared with biomimetic carbonated apatite on dentine bridge formation and inflammatory response in a dental pulp model. International Endodontic Journal, 45, 26-34, 2012. Abstract Aim To evaluate the effects of apatite precipitation on the biocompatibility and hard tissue induction properties of white mineral trioxide aggregate (WMTA) in a dental pulp model. Methodology Pulp exposures were created on the axial walls of 32 sound canine teeth of eight dogs. Four additional sound teeth served as controls. The pulps were capped either with WMTA or apatite derivatives [biomimetic carbonated apatite (BCAp)] in the interaction of WMTA with a synthetic tissue fluid and restored with zinc oxide-eugenol cement. After 7 and 70 days, the animals were killed, and the histological specimens taken from the teeth were stained with haematoxylin and eosin for histomorphological evaluation. The Brown and Brenn technique was employed to stain bacteria. The data were subjected to nonparametric Kruskall-Wallis analysis and Mann-Whitney U_tests. Results Biomimetic carbonated apatite did not induce hard tissue bridge formation. WMTA performed significantly better than BCAp in this respect at both periods ( P < 0.05). BCAp was associated with a significantly greater inflammatory response as compared with WMTA after 7 days ( P < 0.05). Both materials were associated with similar reactions after 70 days ( P > 0.05). Conclusions White mineral trioxide aggregate induced hard tissue formation via a mechanism other than that postulated via apatite formation. [ABSTRACT FROM AUTHOR]

Water is well recognized as an important component in bone, typically regarded as a constituent of collagen, a pore-filling fluid in bone, and an adsorbed species on the surface of bone crystallites. The possible siting and role of water within the structure of the apatite crystallites have not been fully explored. In our experiments, carbonated hydroxyl- and fluorapatites were prepared in DO and characterized by elemental analysis, thermal gravimetric analysis, powder X-ray diffraction, and infrared and Raman spectroscopy. Two hydroxylapatites and two fluorapatites, with widely different amounts of carbonate were analyzed by solid state H NMR spectroscopy using the quadrupole echo pulse sequence, and each spectrum showed one single line as well as a low-intensity powder pattern. The relaxation time of 7.1 ms for 5.9 wt% carbonated hydroxylapatite indicates that the single line is likely due to rapid, high-symmetry jumps in translationally rigid DO molecules, indicative of structural incorporation within the lattice. Discrimination between structurally incorporated and adsorbed water is enhanced by the rapid exchange of surface DO with atmospheric HO. Moreover, a H resonance was observed for samples dried under a variety of conditions, including in vacuo heating to 150°C. In contrast, a sample heated to 500°C produced no deuterium resonance, indicating that structural water had been released by that temperature. We propose that water is located in the c-axis channels. Because structural water is observed even for apatites with very low carbonate content, some of the water molecules must lie between the monovalent ions. [ABSTRACT FROM AUTHOR]

Abstract: In this study, different concentrations of Li2O (0–12wt.%) were substituted for Na2O in 45S5 bioglass® and the effect of these substitutions on both in vitro apatite formation ability and osteoblastic cell responses was studied. For these purposes, the structural and topographical properties of the glasses were studied using, XRD, FTIR, SEM/EDXA and AFM techniques, before and after storing in simulated body fluid for different time intervals. Additionally, the proliferation rate and activity of newborn rat calvaria-derived osteoblastic cells on different samples were examined by using dimethylthiazol diphenyl tetrazolium bromide (MTT) and alkaline phosphatase (ALP) assessment methods. From XRD and FTIR data, it was found that poor crystalline carbonated nanoapatite phase was formed on the surface of glasses with maximum concentration of Li or without Li, while at low substitutions an inhibition of apatite formation was observed. The apatite layer formed on the surfaces of the glasses had similar morphology, flakes which tightly entangled to others. All samples had the same surface roughness before soaking but different values after that. It was found that both proliferation rate and alkaline phosphatase activity of the cells cultured on Li-substituted glasses were higher than those of Li-free sample in a dose-dependent manner. The results suggest that lithia-modified glasses may be successfully used as bone defect filler even with more effectiveness than 45S5 bioglass®. [Copyright &y& Elsevier]

Abstract: Dentin Matrix Protein 1 (DMP1), the essential noncollagenous proteins in dentin and bone, is believed to play an important role in the mineralization of these tissues, although the mechanisms of its action are not fully understood. To gain insight into DMP1 functions in dentin mineralization we have performed immunomapping of DMP1 in fully mineralized rat incisors and in vitro calcium phosphate mineralization experiments in the presence of DMP1. DMP1 immunofluorescene was localized in peritubular dentin (PTD) and along the dentin-enamel boundary. In vitro phosphorylated DMP1 induced the formation of parallel arrays of crystallites with their c-axes co-aligned. Such crystalline arrangement is a hallmark of mineralized collagen fibrils of bone and dentin. Interestingly, in DMP1-rich PTD, which lacks collagen fibrils, the crystals are organized in a similar manner. Based on our findings we hypothesize, that in vivo DMP1 controls the mineral organization outside of the collagen fibrils and plays a major role in the mineralization of PTD. [Copyright &y& Elsevier]

To evaluate the effect of a porous geometry in particulate bone on new bone formation by comparison of anorganic bovine carbonate apatite (ABCA) with synthetic carbonated apatite (SCA), which have similar properties but different micro-structures. Porous structures and anorganic components of ABCA and SCA were evaluated using scanning electron microscope and Fourier transform infrared. They were implanted in maxillary augmentation models with the mouth split design in a total of 15 Beagle dogs. The animals were sacrificed 4, 8 and 16 weeks after surgery, and the histomorphometrical results were statistically analyzed for the material's geometrical relationship and new bone formation in relation to the available space and contact surface for osteoconduction. Both materials showed a typical infrared pattern of CO-substituted hydroxyapatite (HA). Porous structures and a bridging effect of osteoconductive bone material were relatively better observed in SCA. The ratio of the material area to the total area was higher ( P<0.01) for ABCA (28.03±6.09) than for SCA (20.26±4.23). The ratio of the number of particles possessing a pore structure to the total number and the interparticular space was greater ( P<0.001 and 0.01) for SCA (18.12±9.44 and 79.74±4.23) compared with ABCA (1.45±1.74 and 71.63±5.85). The new bone areas and the bone-material contact lengths were greater in SCA than in ABCA ( P<0.05). The present study showed that porous structures may have an influence on new bone formation in osteoconductive bone substitutes. Kim DK, Lee S-J, Cho TH, Hui P, Kwon M-S, Hwang SJ. Comparison of a synthetic bone substitute composed of carbonated apatite with an anorganic bovine xenograft in particulate forms in a canine maxillary augmentation model. Clin. Oral Impl. Res. , 2010; 1334-1344. doi: 10.1111/j.1600-0501.2010.01953.x [ABSTRACT FROM AUTHOR]

Abstract: Introduction: Recently, it was shown that the biomineralization process promoted by the interaction of mineral trioxide aggregate (MTA) with dentin in phosphate-buffered saline (PBS) positively influenced the push-out bond strength of the cement. This study investigated if the use of a PBS intracanal dressing promotes the biomineralization process of MTA apical plugs using an ex vivo apexification model. Methods: White MTA was introduced into single-rooted teeth with standardized artificially created open apices to form 5-mm-thick apical plugs. The specimens were randomly divided into the following three groups of 10 samples each: group 1: the remaining canal space was filled with PBS as an intracanal dressing; group 2: the root segments were introduced in plastic vials containing floral foams with 20 mL of PBS; and group 3: the root segments were placed in the floral foams with 20 mL of PBS and a PBS intracanal dressing was used. After 2 months, the samples were processed for scanning electron microscopic observations. Data were analyzed by using the Kruskall-Wallis test. Results: In group 1, the formation of an interfacial layer (IL) with intratubular mineralization (ITM) was more evident at the cervical third; however, no mineralization was revealed at the apical third. In group 2, there was no IL and/or ITM formation at the cervical third, but samples denoted IL and ITM formation at the apical third. Group 3 displayed the formation of IL and ITM at the different levels. Conclusion: It was concluded that the use of a PBS intracanal dressing promotes the biomineralization process at the inner side of MTA apical plugs. [ABSTRACT FROM AUTHOR]

Abstract: Carbonated apatite ceramics, with a composition similar to that of bone mineral, are potentially interesting synthetic bone graft substitutes. In the present study, two porous carbonated apatite ceramics were developed, characterized and tested for their bone repair capacity and osteoinductive potential in a goat model. Although the two ceramics were prepared from a similar starting powder, their physico-chemical and structural characteristics differed as a consequence of different preparation methods. Both ceramics had an open and interconnected porous structure with a porosity of about 80%. The morphology of the surface of CA-A and CA-B at the submicron level differed significantly: CA-A consisted of irregular grains with a size of 5–20μm, with 1–10μm large micropores among the grains, whereas CA-B surface consisted of much smaller and regular shaped grains (0.05–0.5μm), with most micropores smaller than 1μm. The specific surface area of CA-B was about 10 times larger than that of CA-A due to its significantly smaller grain size. CA-A and CA-B ceramics contained 3 and 5 wt.% of B-type carbonated apatite, respectively. Although neither ceramic succeeded in completely bridging the 17mm iliac wing defect with new bone after 12weeks of implantation, CA-A showed significantly more bone formation in the pores of the implant than CA-B. The total area percentage of new bone in the total defect area was 12.7±1.81 and 5.51±1.37 (mean±SEM) for CA-A and CA-B, respectively. Intramuscular implantation of the ceramics led to ectopic bone formation by CA-A in all three implanted specimens, in contrast to CA-B, where no new bone was observed in any of the 11 animals. CA-A showed a more pronounced degradation than CA-B both in vitro and in vivo at both implantation sites, which was unexpected based on the physico-chemical and structural properties of the two ceramics. Both physico-chemical and structural properties of the ceramics could, dependently or independently, have affected their in vivo behaviour, emphasizing the importance to control individual parameters for successful bone repair. [Copyright &y& Elsevier]

Abstract: The influence of the carbonate content in apatites on the adhesion and the proliferation of MC3T3-E1 osteoblastic cells was investigated. B-type carbonated apatites (DCAps) were prepared by the hydrolysis of monetite (CaHPO4, DCP) in solutions with a carbonate concentration ranging from 0.001 to 0.075moll−1. Stoichiometric hydroxyapatite (DCAp0) was synthesized in carbonate-free solution. MC3T3-E1 cells were seeded on the compacted DCAps and cell adhesion and proliferation were analysed after 24h and 7days, respectively, using a MTS assay and fluorescence microscopy. Cell adhesion tends to increase with increasing carbonate content for carbonate contents between 0 and 6.9wt.% and levels out to an acceptable value (±50% compared to the control) for carbonate contents between 6.9 and 16.1wt.%. Only DCAps with a carbonate content equal to or higher than 11% support high cell proliferation comparable to the control. On the latter DCAps, the cells have a spread morphology and form a near-confluent layer. A decrease in charge density and crystallinity at the apatite surface, as well as the formation of more spheroidal crystals with increasing carbonate content, might attribute to changes in composition and three-dimensional structure of the protein adsorption layer and hence to the observed cell behaviour. Consequently, only DCAps with a high carbonate content, mimicking early in vivo mineralization, are possible candidates for bone regeneration. [Copyright &y& Elsevier]

Introduction: Recently, it was shown that the interaction of each of mineral trioxide aggregate (MTA) and Portland cement with dentin in phosphate-buffered saline (PBS) promotes a biomineralization process that leads to the formation of an interfacial layer with tag-like structures at the cement-dentin interface. This study analyzes the influence of the biomineralization process on the push-out strength of ProRoot MTA (Dentsply Tulsa Dental, Tulsa, OK), MTA Branco (Angelus Soluções Odontológicas, Londrina, PR, Brazil), MTA BIO (Angelus Soluções Odontológicas), or Portland cement with and without calcium chloride. Methods: Dentin discs with standardized cavities were filled with ProRoot MTA, MTA Branco, MTA BIO, white Portland cement + 20% bismuth oxide (PC1), or PC1 + 10% of calcium chloride (PC2). The specimens were randomly divided into two groups: cement in contact with a wet cotton pellet for 72 hours or immersed in PBS for 2 months. The bond strengths were measured with the Instron Testing machine (Model 4444; Instron Corp, Canton, MA), and the fractured surfaces on the root walls were observed by scanning electron microscopy. Results: All samples immersed in PBS displayed a significantly greater resistance to displacement than that observed for the samples in contact with a wet cotton pellet for 72 hours (p < 0.05). MTAs displayed a significantly greater resistance to displacement than Portland cements. Conclusion: It was concluded that the biomineralization process positively influenced the push-out bond strength of the cements, particularly the MTA groups. [Copyright &y& Elsevier]

Culture and characterisation of porcine osteoprogenitors were established in order to study the differentiation of osteoblast in a hybrid material of carbonated apatite (CAp) (patent under process no. PI 20042321) and autologous cells that can be used later as an advanced bone graft material. Cells were obtained from bone marrow and cultured onto CAp of wet synthesis and onto Thermanox, with or without differentiation factors in time course experiments, at the end of which biochemical and molecular markers of osteogenesis were obtained. Results indicated that this model is useful to study the functionality of a hybrid material of synthetic CAp and autologous osteoprogenitor cells derived from porcine bone marrow. [ABSTRACT FROM AUTHOR]