The blocking effect and abrasion resistance of hydroxyapatite with different particle sizes and morphologies for dentinal tubules

To study the blocking effect and abrasion resistance of hydroxyapatite (HA) with differentparticle sizes and morphologyies on dentinal tubules from the qualitative and quantitative aspects.

Dentindiscs were etched and divided into 4 groups randomly: 20 nm HA group; 30 nm HA group; 12 μm HA group; controlgroup (without any experimental treatment). Each group was brushed with correspondent materials for 7 days. Then, thedentin disk was divided into two parts, the one was detected by the scanning electron microscopy (SEM); the other wasobserved by SEM after toothbrush abrasion test. The Image-Pro Plus 6.0 image analysis software was used to calculatethe plugging rate of dentinal tubules.

SEM showed that the blockage is granular, the plugging rate of the den-tinal tubules were about 82% to 96%. 30 nm HA group (short rod) range the first in the average plugging rate, followedby the 20 nm HA group (needles) and 12 μm HA group (spherical). After mechanical brushing for 7 days, SEM imagesshowed that deposited layer in each group was smooth and compact, and more than 63% of the tubules still had beenblocked.

HA with different particle sizes and morphologies had good plugging effect and abrasion resis-tance on dentine tubules. The blocking effect of HA was affected not only by particle size but also by the morphology.