Takashi Komabayashi

Properties of a new injectable type of root canal filling resin with adhesiveness to dentin

The properties of a new, injectable type of root canal wall, adhesive filling resin, which we developed, were studied for its physical properties, adhesiveness to dentin and the root canal, and sealing ability. The new resin consisted of a powder composed of a specially selected poly(methyl methacrylate) and barium sulfate radiopacifier and liquid composed of methyl methacrylate monomer and tributylborane catalyst. A mixture of both components had a consistency suitable for injection. The physical properties, including radiopacity, were evaluated according to the ISO standard. The adhesiveness to dentin and the root canal was investigated by bond strength testing or by scanning electron microscopy. The apical sealing ability of the new resin was compared by a dye penetration test with that of gutta-percha/sealer. The findings of this study indicated that the new filling resin had physical properties satisfying all the ISO requirements for dental root canal sealing materials: a tensile bond strength to dentin of 7.3 MPa, a significantly better sealing ability compared with gutta-percha/sealer, the capability of forming resin tags in dentinal tubules, and removability.

Particle Size and Shape Analysis of MTA Finer Fractions Using Portland Cement

The aim of this study was to observe particle length, width, perimeter, and aspect ratio of mineral trioxide aggregate finer fractions using Portland cement. The High Power Field mode of the flow particle image analyzer was used for analysis. Images of particle samples were automatically collected by the analyzer along with analysis parameters. Mean, standard deviation, and the number of particles were calculated in each group. Parameters of length, width, and perimeter did not show a statistical significance when groups were compared. Examining the parameter of aspect ratio, there was evidence of a statistical significance seen (p<0.05). The cumulative percentage of particles that were between 0.5 and 3 microm in size was 88%. Fine particles may penetrate dentin tubules. The average aspect ratio was 0.744 (SD=0.155). It can be speculated that a dentin tubule occlusion pattern is dependent on the aspect ratio.