Utility of biphasic calcium phosphate cement as a seal for root-end filling.

The recently developed biphasic calcium phosphate cement (BCPC) consists of α-tricalcium phosphate-tetracalcium phosphate as the solid phase and calcium phosphate solution as the liquid phase. BCPC powder is composed of a single solid solution with a monomodal size distribution. Here, we used a bacterial leakage model to examine the utility of BCPC as a seal for root-end filling. We prepared large (median particle size=9.96 µm; BCPC-L) and small (median particle size=4.84 µm; BCPC-S) BCPC powders. In total, 45 single-rooted teeth were instrumented, resected at the root-end, and retrofilled with experimental materials. Mineral trioxide aggregate (MTA) was used as the control. After visual confirmation of BCPC powder size and retrofilling quality by microscopy, bacterial leakage tests were conducted using Enterococcus faecalis. The bacterial leakage tests did not reveal any significant differences between BCPC-S and MTA. Our findings suggest that BCPC-S is useful for root-end filling.

Observation and Stereochemistry of Betaine Intermediates in the Reaction of Phosphonium Ylide Containing a Phosphaboratatriptycene Skeleton with Benzaldehyde.

Betaine intermediates, rather than the corresponding 1,2-oxaphosphetanes, were observed in the reaction of the phosphonium ylide containing a phosphaboratatriptycene skeleton with PhCHO in THF. Their chemical shifts were -4.56, -4.92, -7.32, and -11.1 ppm at -10 °C in variable temperature (VT) 31P{1H} NMR experiments. These signals were observed by the deprotonations of ß-hydroxyalkylphosphonium salts with lithium hexamethyldisilazide (LiHMDS) and sodium hexamethyldisilazide (NaHMDS). Their signals were assigned to betaine lithium complexes and salt-free betaines, respectively. The betaine lithium complexes were thermodynamically stable even at 25 °C and were converted to ß-hydroxyalkylphosphonium salts by protonation, whereas the salt-free betaines were unstable, providing the corresponding ethylphosphonium salt and PhCHO at 0 °C, instead of olefins and phosphine oxide. The potential structures of the betaine lithium complexes and salt-free betaines were investigated by optimizing the expected stereoisomers and estimating the phosphorus chemical shifts by density functional theory (DFT) calculations. The results indicated that the erythro-syn- and threo-syn-betaines were more stable than their anti-forms. Erythro-syn-betaines were the most thermodynamically stable among the expected stereoisomers in both lithium complexes and salt-free betaines. The estimated phosphorus-31 signals were in good agreement with those experimental values.

Involvement of the calcium-sensing receptor in mineral trioxide aggregate-induced osteogenic gene expression in murine MC3T3-E1 cells.

Mineral trioxide aggregate (MTA) has excellent biocompatibility as well as bioactivity, including an ability to induce osteoblast differentiation. We examined the effects of the calcium-sensing receptor (CaSR) on osteogenic gene expression induced by MTA. MC3T3-E1 cells were cultured with or without (control) MTA. The expression levels of Runx2, type I collagen, and CaSR genes were analyzed by real-time polymerase chain reaction and their products were measured using enzyme-linked immunosorbent assays. The levels were increased significantly in cells exposed to MTA compared with control. Next, MC3T3-E1 cells were cultured with MTA and EGTA (a calcium chelator), because calcium ions were released continuously from MTA into the culture. Expression levels were decreased to control levels by MTA plus EGTA. NPS2143 (a CaSR antagonist) also reduced MTA-induced gene expression. These results suggest that MTA induced osteogenic gene expressions of Runx2 and type I collagen via CaSR in MC3T3-E1 cells.

Evaluation of Qualitative Changes in Simulated Periodontal Ligament and Alveolar Bone Using a Noncontact Electromagnetic Vibration Device with a Laser Displacement Sensor.

Evaluating periodontal tissue condition is an important diagnostic parameter in periodontal disease. Noncontact electromagnetic vibration device (NEVD) was previously developed to monitor this condition using mechanical parameters. However, this system requires accelerometer on the target tooth. This study assessed application of laser displacement sensor (LDS) to NEVD without accelerometer using experimental tooth models. Tooth models consisted of cylindrical rod, a tissue conditioner, and polyurethane or polyurethane foam to simulate tooth, periodontal ligament, and alveolar bone, respectively. Tissue conditioner was prepared by mixing various volumes of liquid with powder. Mechanical parameters (resonant frequency, elastic modulus, and coefficient of viscosity) were assessed using NEVD with the following methods: Group A, measurement with accelerometer; Group B, measurement with LDS in the presence of accelerometer; and Group C, measurement with LDS in the absence of accelerometer. Mechanical parameters significantly decreased with increasing liquid volume. Significant differences were also observed between the polyurethane and polyurethane foam models. Meanwhile, no statistically significant differences were observed between Groups A and B; however, most mechanical parameters in Group C were significantly larger and more distinguishable than those of Groups A and B. LDS could measure mechanical parameters more accurately and clearly distinguished the different periodontal ligament and alveolar bone conditions.

Effect of a novel fluorapatite-forming calcium phosphate cement with calcium silicate on osteoblasts in comparison with mineral trioxide aggregate.

We compared the effects of treatment with fluorapatite-forming calcium phosphate cement (FA-forming CPC) containing tricalcium silicate (TCS) and those of mineral trioxide aggregate (MTA), the gold standard endodontic cement, on cultured osteoblast-like cells (ROS 17/2.8 cells; ROS cells). The FA-forming CPC powder consisted of 61.29% CaHPO4, 32.26% CaCO3, and 6.45% NaF. One part TCS was combined with nine parts FA-forming CPC powder to make FA-forming CPC with TCS. A 1.5-M phosphate solution was mixed as a cement liquid with a powder/liquid ratio of 2.22. Cell culture was carried out using cell culture inserts, whereby each test material was put on a porous membrane insert in the cell culture plate. Proliferation, morphologic changes, and alkaline phosphatase activity in ROS cells were measured in the presence of FA-forming CPC with TCS and MTA and compared. The logarithmic growth phase and cellular morphologic changes in ROS cells were identical in all experimental groups. Additionally, no significant difference in alkaline phosphatase activity was noted in ROS cells exposed to FA-forming CPC with TCS and those exposed to MTA. In conclusion, FA-forming CPC with TCS has characteristics identical to those of MTA under the present experimental conditions and may thus be useful for endodontic applications.

Development of a novel fluorapatite-forming calcium phosphate cement with calcium silicate: in vitro and in vivo characteristics.

Aim of this study was to develop a novel fluorapatite-forming calcium phosphate cement (FA-CPC) with tricalcium silicate (TCS) for endodontic applications and to examine its in vitro and in vivo characteristics. The FA-CPC powder consisted of 62.8% CaHPO4, 30.8% CaCO3, and 6.4% NaF. One part of TCS was combined with 9 parts of FA-CPC powder (FA-CPC with TCS). A 1.5 M phosphate solution was used as cement liquid. Setting time (ST), diametral tensile strength (DTS), phase composition by X-ray diffraction (XRD), and cement alkalinity were analyzed. Cement biocompatibility was assessed using rat subcutaneous model. Cement ST was 10.3±0.6 min and DTS was 3.89±0.76 MPa. XRD patterns showed that highly crystalline apatitic material was the only significant phase present and pH value was approximate 11.0. FA-CPC with TCS demonstrated similar biocompatibility as that of mineral trioxide aggregate control. These results suggest that FA-CPC with TCS may be useful for endodontic applications.