The Influence of 2-Methacryloyloxyethyl Phosphorylcholine Polymer Materials on Orthodontic Friction and Attachment of Oral Bacteria.

There is no clinical evidence of the usage of 2-methacryloyloxyethyl phosphorylcholine (MPC) polymers in dental practice. We performed in vitro studies to determine whether the application of an MPC coating to stainless steel orthodontic wires confers low-friction and antimicrobial properties to these wires. The friction test on MPC-coated wires was performed using a precision universal/tensile tester. MPC polymer was coated on a 50 × 50 mm stainless steel plate, and samples were assessed using an antimicrobial activity test. To verify the effect of MPC polymer-treated wires on experimental tooth movement models in vitro, examinations were performed on typodonts to determine the improvement in tooth movement efficiency. The polymer treatment wire groups demonstrated significantly enhanced tooth movement compared with the untreated wire groups, at both 50 g and 100 g traction forces. The results indicated that MPC coating inhibited the attachment of oral bacteria, such as Streptococcus mutans, on a stainless steel plate. Additionally, the coating seemed to improve the efficiency of tooth movement by reducing the occurrence of friction. The application of an MPC coating onto stainless steel wires, which are used as orthodontic materials, may reduce static friction and bacterial adherence to the oral cavity and improve tooth movement.

Degradation of phospholipid polymer hydrogel by hydrogen peroxide aiming at insulin release device.

The purpose of this study is to ascertain the applicable possibility of H(2)O(2) degradable hydrogel for fabrication of insulin release system synchronized with the change in the glucose concentration in the medium. The hydrogel was prepared by using 2-methacryloyloxyethyl phosphorylcholine (MPC) and crosslinker. The favorable characteristic of the hydrogel was H(2)O(2) concentration responsive degradation. The H(2)O(2) was utilized and produced by enzymatic reaction between glucose oxidase and glucose. Poly(MPC) (PMPC) was easily degraded in H(2)O(2) aqueous solution, and the PMPC hydrogel was also degraded in H(2)O(2) aqueous solution. The degradation mechanism was considered to be main chain scission of PMPC. The degradation profile was evaluated by using weight swelling ratio and volume swelling ratio. The weight swelling ratio of PMPC hydrogel firstly increased due to the reduction of crosslink density, then the ratio decreased to zero (complete degradation). The degradation profile was proportional to the H(2)O(2) concentration. Furthermore, volume swelling ratio also increased, and complex elastic modulus decreased with degradation in H(2)O(2) aqueous solution. These results indicated that the hydrogel was degraded by hydroxy and/or hydroperoxy radicals which was produced by H(2)O(2), the crosslink density and mechanical property decreased. The release profile from the hydrogel was estimated by using lipid microsphere (LM) as an insulin model. The LM was released with the degradation of PMPC hydrogel. Taking these results into account, the PMPC hydrogel was available for H(2)O(2) degradable hydrogel for synchronization with glucose concentration by using enzymatic reaction.

Preparation of cross-linked biocompatible poly(2-methacryloyloxyethyl phosphorylcholine) gel and its strange swelling behavior in water/ethanol mixture.

Functional cross-linked poly(2-methacryloyloxyethyl phosphorylcholine(MPC)) gels were prepared with various cross-linkers by conventional radical polymerization in aqueous media. The poly(MPC) gels swelled in water and have a large degree of swelling compared with that of poly(2-hydroxyethyl methacrylate). The swelling degree of the poly(MPC) gel equilibrated in water depended on the chemical structure and composition of the cross-linkers, but did not change in an aqueous medium with pH and ionic concentrations. On the other hand, the volume of poly(MPC) gel changed sharply with a change in the composition of water/ethanol mixtures. Although in mixtures containing 70-90 vol% of ethanol the gel volume was nearly 10% of that in water, in pure ethanol it was almost the same as in water. The change in the volume of the poly(MPC) gel observed in a water/ethanol mixture was completely reversible. We conclude that this so-called re-entrant phenomenon was derived from the co-nonsolvency of poly(MPC) in the water/ethanol mixture triggered by an imbalance in the delicate interaction force between the molecules of water, ethanol, and poly(MPC).