Mineral trioxide aggregate (MTA) was developed in early 1990s and has been successfully used for root perforation repair, root end filling, and one-visit apexification. MTA is composed mainly of tricalcium silicate and dicalcium silicate. When MTA is hydrated, calcium silicate hydrate (CSH) and calcium hydroxide is formed. Formed calcium hydroxide interacts with the phosphate ion in body fluid and form amorphous calcium phosphate (ACP) which finally transforms into calcium deficient hydroxyapatite (CDHA). These mineral precipitate were reported to form the MTA-dentin interfacial layer which enhances the sealing ability of MTA. Clinically, the use of zinc oxide euginol (ZOE) based materials may retard the setting of MTA. Also, the use of acids or contact with excessive blood should be avoided before complete set of MTA, because these conditions could adversely affect the hydration reaction of MTA. Further studies on the chemical nature of MTA hydration reaction are needed.
Aluminum Compounds ; Apexification ; Body Fluids ; Calcium ; Calcium Compounds ; Calcium Hydroxide ; Calcium Phosphates ; Drug Combinations ; Durapatite ; Glutamates ; Guanine ; Hydroxides ; Oxides ; Silicates ; Silicic Acid ; Zinc Oxide ; Pemetrexed

PURPOSE: We evaluated the influence of urinary stone components on the outcomes of ureteroscopic removal of stones (URS) by electrohydraulic lithotripsy (EHL) in patients with distal ureteral stones. MATERIALS AND METHODS: Patients with a single distal ureteral stone with a stone size of 0.5 to 2.0 cm that was completely removed by use of EHL were included in the study. Operating time was defined as the time interval between ureteroscope insertion and complete removal of ureteral stones. Ureteral stones were classified into 5 categories on the basis of their main component (that accounting for 50% or more of the stone content) as follows: calcium oxalate monohydrate (COM), calcium oxalate dihydrate, carbonate apatite (CAP), uric acid (UA), and struvite (ST). RESULTS: A total of 193 patients (131 males and 62 females) underwent EHL. The mean operating time was 25.1+/-8.2 minutes and the mean stone size was 1.15+/-0.44 cm. Calcium oxalate stones accounted for 64.8% of all ureteral stones, followed by UA (19.7%), CAP (8.3%), and ST (7.2%) stones. The mean operating time was significantly longer in the UA group (28.6+/-8.3 minutes) than in the COM group (24.0+/-7.8 minutes, p=0.04). In multivariate analyses, the stone size was negatively associated with the odds ratio (OR) for successful fragmentation. UA as a main component (OR, 0.42; 95% confidence interval, 0.20 to 0.89; p=0.023) was also found to be significantly important as a negative predictive factor of successful fragmentation after adjustment for stone size. CONCLUSIONS: The results of the present study suggest that successful fragmentation by URS with EHL could be associated with the proportion of the UA component.
Accounting ; Apatites ; Calcium Oxalate ; Carbon ; Humans ; Lithotripsy ; Magnesium Compounds ; Male ; Multivariate Analysis ; Odds Ratio ; Phosphates ; Ureter ; Ureteroscopes ; Ureteroscopy ; Uric Acid ; Urinary Calculi

PURPOSE: The signal of intracranial calcification on magnetic resonance (MR) imaging has been known to bevariable. The purpose of this study was to evaluate the MR signal of calcifications according to calciumconcentration and compound. MATERIALS AND METHODS: T1-weighted, proton density and T2-weighted images were obtained in phantoms with various conposition of calcium carbonate and calcium phosphate. The signal intensities and T1/T2 relaxation times were measured and analyzed according to calcium concentration and compound. The configurations of calcium particles were evaluated by scanning electron microscopy. RESULTS: The signal intensity of calcium carbonate on T1-weighted images gradually decreased as the concentration increased, while that ofcalcium phosphate showed a biphasic curve with a peak intensity at 0.2 g/ml. The signal intensity of both calcium compounds on T2-weighted images decreased as the concentration increased. The T1 relaxation time of calcium carbonate remained constant with increasing calcium concentration, however, that of calcium phosphate decreased upto 0.2g/ml and then remained constant. The T2 relaxation time of both calcium compounds decreased in a similar fashion with increasing concentration. Calcium phosphate showed larger surface area on scanning electron microscope. CONCLUSION: Calcifications show variable MR signal due to difference of T1 and T2 relaxation times according to calcium concentration and compound. Large surface area of calcium particle might cause shortening of T1 relaxation time leading to high signal on T1-weighted image. Understanding of these findings will help interpretation of MR images more precisely.
Calcium Carbonate ; Calcium Compounds ; Calcium* ; Microscopy, Electron, Scanning ; Protons ; Relaxation

OBJECTIVES: This in vitro study investigated whether short-term application of calcium hydroxide in the root canal system for 1 and 4 wk affects the fracture strength of human permanent teeth. MATERIALS AND METHODS: Thirty two mature human single rooted mandibular premolars in similar size and dentin thickness without decay or restorations were hand and rotary instrumented and 16 teeth vertically packed with calcium hydroxide paste and sealed coronally with caviton to imitate the endodontic procedure and the other 16 teeth was left empty as a control group. The apicies of all the samples were sealed with resin, submerged in normal saline and put in a storage box at 37degrees C to mimic the oral environment. After 1 and 4 wk, 8 samples out of 16 samples from each group were removed from the storage box and fracture strength test was performed. The maximum load required to fracture the samples was recorded and data were analysed statistically by the two way ANOVA test at 5% significance level. RESULTS: The mean fracture strengths of two groups after 1 wk and 4 wk were similar. The intracanal placement of calcium hydroxide weakened the fracture strength of teeth by 8.2% after 4 wk: an average of 39.23 MPa for no treatment group and 36.01 MPa for CH group. However there was no statistically significant difference between experimental groups and between time intervals. CONCLUSIONS: These results suggest that short term calcium hydroxide application is available during endodontic treatment.
Bicuspid ; Calcium ; Calcium Hydroxide ; Calcium Sulfate ; Dental Cements ; Dental Pulp Cavity ; Dentin ; Hand ; Humans ; Hydrazines ; Hydroxides ; Root Canal Filling Materials ; Tooth ; Vinyl Compounds ; Zinc Oxide

ABSTRACT PURPOSE: Synthetic bone products such as biphasic calcium phosphate (BCP) are mixtures of hydroxyapatite (HA) and a- tricalcium phosphate (a- TCP). In periodontal therapies and implant treatments, BCP provides to be a good bone reconstructive material since it has a similar chemical composition to biological bone apatites. The purpose of this study was to compare bone regeneration capacity of two commercially available BCP. METHODS: Calvarial defects were prepared in sixteen 9-20 months old New Zealand White male rabbits. BCP with HA and a- TCP (70:30) and BCP with Silicon-substituted hydroxyapatite (Si-HA) and a-TCP (60:40) particles were filled in each defect. Control defects were filled with only blood clots. Animals were sacrificed at 4 and 8 week postoperatively. Histomorphometric analysis was performed. RESULTS: BCP with HAand a- TCP 8 weeks group and BCP with Si-HA and a- TCP 4 and 8 weeks groups showed statistically significant in crease (P<0.05) in augmented area than control group. Newly formed bone area after 4 and 8 weeks was similar among all the groups. Residual materials were slightly more evident in BCP with HA and a- TCP 8 weeks group. CONCLUSIONS: Based on histological results, BCP with HA and a- TCP and BCP with Si-HA and a- TCP appears to demonstrate acceptable space maintaining capacity and elicit significant new bone formation when compared to natural bone healing in 4 and 8 week periods.
Animals ; Apatites ; Bone Regeneration ; Bone Substitutes ; Calcium ; Calcium Phosphates ; Durapatite ; Humans ; Hydroxyapatites ; Male ; New Zealand ; Osteogenesis ; Rabbits

PURPOSE: The objective of this study was to investigate the effects of calcium phosphate coated titanium implant surface on bone response and implant stability at early stage of healing period of 3 weeks and later healing period of 6 weeks. MATERIAL AND METHODS: A total of 24 machined, screw-shaped implants (Dentium Co., Ltd., Seoul, Korea) which dimensions were 3.3 mm in diameter and 5.0 mm in length, were used in this research. All implants (n = 24), made of commercially pure (grade IV) titanium, were divided into 2 groups. Twelve implants (n = 12) were machined without any surface modification (control). The test implants (n = 12) were anodized and coated with thin film (150 nm) of calcium phosphate by electron-beam deposition. The implants were placed on the proximal surface of the rabbit tibiae. The bone to implant contact (BIC) ratios was evaluated after 3 and 6 weeks of implant insertion. RESULTS: The BIC percentage of calcium phosphate coated implants (70.8 +/- 18.9%) was significantly higher than that of machined implants (44.1 +/- 16.5%) 3 weeks after implant insertion (P = 0.0264). However, there was no significant difference between the groups after 6 weeks of healing (P > .05). CONCLUSION: The histomorphometric evaluation of implant surface revealed that: 1. After 3 weeks early healing period, bone to implant contact (BIC) percentage of calcium phosphate coated implants (70.8%) was much greater than that of surface untreated machined implants (44.1%) with P = 0.0264. 2. After 6 weeks healing period, however, BIC percentage of calcium phosphate coated implants group (79.0%) was similar to the machined only implant group (78.6%). There was no statistical difference between two groups (P = 0.8074). 3. We found the significant deference between the control group and experimental group during the early healing period of 3 weeks. But no statistical difference was found between two groups during the later of 6 weeks.
Calcium ; Calcium Phosphates ; Nitrogen Mustard Compounds ; Tibia ; Titanium

The porous scaffolds for bone tissue engineering were prepared by foam impregnation. The magnesium and aluminum acid phosphates were used as bonder and the hydroxyapatite ((Ca10 (PO4)6(OH)2, HA) powder as raw materials. Scanning electron microscopy (SEM) examination indicated that the 3D interconnected porous structure of the organic foam was replicated well by the scaffolds calcined at high temperature and the structural requirement of tissue engineering was satisfied. XRD analysis showed that the scaffold was composed of HA and Ca7Mg2P6O24 while calcined at 1150 degrees C for shorter time and of (Ca, Mg)3(PO4)2 when the time prolonged to 2 h. There was no peak of CaO found in the scaffolds by XRD. According to the culture in vitro, the scaffold possesses good biocompatibility and certain degree of degradability.
Aluminum Compounds ; chemistry ; Biocompatible Materials ; Bone Substitutes ; chemistry ; Calcium Phosphates ; chemistry ; Durapatite ; chemistry ; Phosphates ; chemistry ; Porosity ; Tissue Engineering

The purpose of this study was to compare mineral trioxide aggregate (MTA; Dentsply, Tulsa Dental, Tulsa, OK, USA), which is widely used as root-end filling material, with DiaRoot BioAggregate (DB; Innovative BioCaramix Inc, Vancouver, BC, Canada), newly developed product, by using MG63 osteoblast-like cells. MTA, DB, and Intermediate Restorative Material (IRM; Dentsply Caulk, Milford, DE, USA) were used for root-end filling material while tissue culture plastic was used for control group. Each material was mixed and, the mixtures were left to set for 24 hours. MG63 cells were seeded to each group and then they were cultured for attachment for 4 hours. Following the attachment of cells to the root-end filling material, early cellular response was observed. After another 12 hours'culture, the level of attachment between cells and material was observed and in order to identify the effect of each material to bone formation, transforming growth factor beta1 (TGFbeta1) and osteocalin (OC) were estimated by using enzyme-linked immunosorbent assay (ELISA), and the amount of alkaline phosphatase (ALP) was also measured. The data were analyzed using one-way ANOVA. As a result, only at OC and the number of cells which were attached to materials, there was no statistical difference between MTA and DB. At other items, there was statistically significant difference in all groups. Although DB has not shown exactly the same cellular response like that of MTA, the number of attached cells shows that biocompatibility of the material and OC indicates bone formation rate. Therefore, if DB is used for root end filling material, it is expected to lead to similar results to MTA.
Alkaline Phosphatase ; Aluminum Compounds ; Calcium Compounds ; Calcium Hydroxide ; Drug Combinations ; Enzyme-Linked Immunosorbent Assay ; Glutamates ; Guanine ; Hydroxyapatites ; Osteogenesis ; Oxides ; Plastics ; Polymethyl Methacrylate ; Seeds ; Silicates ; Transforming Growth Factor beta1 ; Pemetrexed

Studies on bioactive glass and glass-ceramic are important research high-lights in the field of biomedical materials. Due to their bioactivity, these materials can form a tight chemical bond with the living bone, when implanted. As a preeminent kind of these materials, A-W(Apatite/Wollastonite) bioactive glass ceramic has not only the excellent bioactivity and biocompatibility, but also the eminent mechanical properties, so it has been largely applied and developed in clinical practice. The development, preparation, properties, applications and the mechanism of its bond with bone are introduced in this paper. We will also put forward the prospect of the research and development of A-W bioactive glass ceramic.
Apatites ; chemistry ; Bone Substitutes ; chemistry ; Calcium Compounds ; chemistry ; Ceramics ; chemistry ; Mechanics ; Research ; Silicates ; chemistry ; Surface Properties

In this paper, alpha-tricalcium phosphate (alpha-TCP) and tetracalcium phosphate (TTCP) respectively were chosen as basic compositions of phosphate bone cements. Other auxiliary materials such as hydroxyapatite (HAP), dicalcium phosphate dihydrate (DCPD), calcium carbonate (CaCO3), calcium oxide (CaO) and amorphous calcium silicate (CaSiO3) were added in the cements. Six kinds of composite bone cements were decided with 1.50 as their Ca/P ratio. Then the primary properties of them were studied. Ringer's simulated body fluid (SBF) tests were carried out for the samples. The changes of pH value in SBF and the compressive strength of the samples with the immersion time were studied. The results showed: the mixing liquid 0.25 M K2HPO4/KH2PO4 and amorphous CaSiO3 were effective for accelerating the setting of the cements; the initial setting time (It) was about 4-5.5 min and the final setting time (Ft) was about 18-19. 5 min. Amorphous calcium silicate can increase the compressive strength of the bone cements remarkably; the compressive strength of the alpha-TCP bone cement with the addition of suitable amount amorphous CaSiO3 reached 45.3 MPa after immersion in SBF for 14 days.
Bone Cements ; chemical synthesis ; chemistry ; Calcium Compounds ; chemistry ; Calcium Phosphates ; chemistry ; Compressive Strength ; Humans ; Silicates ; chemistry