Thermally induced crystallization and phase evolution in powders derived from amorphous calcium phosphate precipitates with a Ca/P ratio of 1:1

2016 ◽  
Vol 450 ◽  
pp. 190-196 ◽  
Author(s):  
Zoltan Zyman ◽  
Matthias Epple ◽  
Anton Goncharenko ◽  
Dmytro Rokhmistrov ◽  
Oleg Prymak ◽  
...  
CrystEngComm ◽  
2021 ◽  
Author(s):  
Diana Griesiute ◽  
Lauryna Sinusaite ◽  
Agne Kizalaite ◽  
Andris Antuzevics ◽  
Kestutis Mazeika ◽  
...  

The present study investigates thermally induced crystallization and phase evolution of amorphous calcium phosphate (ACP) partially substituted with Fe3+ ions (M/P = 1.5 : 1). It was demonstrated that the...


2018 ◽  
Vol 20 (46) ◽  
pp. 29221-29235 ◽  
Author(s):  
Vuk Uskoković ◽  
Smilja Marković ◽  
Ljiljana Veselinović ◽  
Srečo Škapin ◽  
Nenad Ignjatović ◽  
...  

Transformations between amorphous and crystalline apatite mechanistically govern some of the most essential processes in bone metabolism, including biomineralization and bone remodeling.


2017 ◽  
Vol 11 (2) ◽  
pp. 147-153 ◽  
Author(s):  
Zoltan Zyman ◽  
Anton Goncharenko ◽  
Dmytro Rokhmistrov

The phase evolution in amorphous calcium phosphate (ACP, with a Ca/P ratio of 1 : 1), derived from the fast nitrate synthesis using different conditions, was studied in temperature range 20-980?C. ACP crystallized within 600-700?C and the phase composition depended on the synthesis duration. It was firstly revealed that for an extremely short synthesis (1min) two metastable phases ??-CPP and ??-TCP of the high-temperature calcium pyrophosphate ?-CPP and tricalcium phosphate ?-TCP were crystallized. For a longer synthesis (5min), ??- CPP and minor ?-CPP crystallized. The metastable phases gradually transformed to stable polymorphs ?-CPP and ?-TCP above 800?C, and a biphasic mixture ?-CPP/?-TCP or ?-CPP formed at 980?C. The crystallization of the metastable phases was attributed to the Ostwald step rule. A mechanism for the formation of TCP (Ca/P = 1.5) from ACP (Ca/P = 1) was proposed. The prepared powders of ?-CPP/?-TCP, ?-CPP or initial ACP were fine-grained and would have enhanced sinterability. Contribution to the densification was demonstrated due to the thermal transformation of the metastable polymorphs into stable phases having higher densities.


2011 ◽  
Vol 306-307 ◽  
pp. 11-15
Author(s):  
Cheng Feng Li ◽  
Xiao Lu Ge ◽  
Jia Hai Bai ◽  
Guo Chang Li

The influence of citric acid on phase evolution of calcium phosphate is studied by the electrical conductivity of reaction solutions. The conductance curves are divided into three distinct regions and assigned to the formation of amorphous calcium phosphate (ACP), hydroxyapatite (HA) and the solubility of HA, respectively. When more citric acid is added, the width of region I decreases because more Ca2+ ions would prefer to foster the nucleation of HA from ACP. Decreasing rate of conductivity in region II becomes smaller with more addition of citric acid because the supersaturation of HA decreases in solutions. And thus, HA powders with larger grain size are synthesized with more citric acid addition.


2017 ◽  
Vol 758 ◽  
pp. 162-165
Author(s):  
Nobuhiro Kato ◽  
Yuki Ido ◽  
Ei Yamamoto ◽  
Shigeki Hontsu

In cosmetic dentistry, bleaching and laminate veneer methods are common treatments to improve the appearance of teeth. However, there are limitations to these treatments, as they damage the enamel which are not capable of recovering naturally. In this study, novel hydroxyapatite (HAp) sheets, which enable both enamel restoration and aesthetic treatments, were developed. Results indicated that the lower range of the sintering temperatures, of the pulsed laser deposition targets, produced lighter shades of amorphous Calcium phosphate (ACP) sheets. Subsequently, the post-annealing process of the sheets induced crystallization processes of the ACP sheets, to form HAp sheets, and improved the shade rank of the sheet. The shade rank of the developed sheet (6.8 ± 0.2) was almost comparable to the average shade rank of the teeth of Japanese people, within a range of 6.5 to 7.0.


2021 ◽  
pp. 1-10
Author(s):  
Ahmed Sleibi ◽  
Anwar R. Tappuni ◽  
Aylin Baysan

Different formulas of topical fluoride have been used to manage root carious lesions. This clinical trial aimed to investigate the efficacy of a dental varnish containing casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) and fluoride compared with fluoride alone in reversing/arresting root caries in xerostomic patients over 1 year. A total of 80 patients (age range 45–92 years) with primary root caries (<i>n</i> = 184 root carious lesions) and unstimulated salivary flow rate of &#x3c;0.2 mL/min were randomly allocated to receive either dental varnish containing CPP-ACP and 5% fluoride (group 1: MI varnish; GC, Japan) (<i>n</i> = 41, 83 lesions), or dental varnish with 5% fluoride alone (group 2: NUPRO White; Dentsply, USA) (<i>n</i> = 39, 101 lesions). Clinical assessments with Severity Index (SI) for root caries, DIAGNOdent measurements, and varnish application were carried out at baseline, 3, 6, and 12 months. Standard oral hygiene instructions with 1,450 ppm fluoride toothpastes were provided for both groups. After 3 months, 63.9% (<i>n</i> = 46) of root caries in group 1 became hard (SI: 0) compared with 39.3% (<i>n</i> = 35) in group 2 (<i>p</i> &#x3c; 0.01). After 6 and 12 months, the differences in SI were insignificant (group 1, <i>n</i> = 60, 83.3%) (group 2, <i>n</i> = 66, 74.2%) (<i>p</i> = 0.36), and (group 1, <i>n</i> = 60, 89.6%) (group 2, <i>n</i> = 67, 81.7%, <i>n</i> = 1 soft, 1.2%) (<i>p</i> = 0.29), respectively. In both groups, noncavitated leathery lesions were more likely to become hard when compared to the cavitated root caries. A significant decrease in plaque index, surface roughness, lesion dimension, and DIAGNOdent readings with a significant increase in lesion distance from the gingival margin was reported in both groups (<i>p</i> &#x3c; 0.05). This study has provided evidence that fluoride dental varnish either with or without calcium and phosphate has the potential to arrest/reverse root caries, especially noncavitated lesions for patients with xerostomia.


Author(s):  
Alexandria J. Hoeher ◽  
Sebastian T. Mergelsberg ◽  
Olaf J. Borkiewicz ◽  
F. Marc Michel

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