Id. Owadally et al., BIOLOGICAL PROPERTIES OF IRM(R) WITH THE ADDITION OF HYDROXYAPATITE AS A RETROGRADE ROOT FILLING MATERIAL, Endodontics & dental traumatology, 10(5), 1994, pp. 228-232
The effect of adding 10% & 20% hydroxyapatite (HAP) on the antibacteri
al activity and cytotoxicity of IRM (Intermediate Restorative Material
) when used as a retrograde root filling was compared with amalgam, a
commonly used material. The antibacterial activity was assessed using
the agar diffusion inhibitory test. Forty standardized pellets of each
material were produced. Fresh materials, and materials aged for 1 wee
k in sterile distilled water, were placed on blood agar plates inocula
ted with Streptococcus anginosus (milleri) or Enterococcus faecalis. T
he presence and diameter of zones of inhibition were recorded at inter
vals of 3, 7 and 10 days. There was no statistically significant overa
ll difference in the response of the two bacteria tested. However, the
re were statistically significant overall differences in diameters of
the zones of inhibition related to different materials, period of expo
sure and ageing of materials (P < 0.001). The diameter of the zones of
inhibition increased with time for all materials, fresh and aged. IRM
and both the HAP-modified forms produced large zones of inhibition wh
ether aged or fresh, regardless of period of exposure and was differen
t from the other materials (P < 0.001). The cytotoxicity was assessed
using the Millipore filter method. Ten standardized pellets of each ma
terial were produced and aged by storage in sterile distilled water fo
r 72 h. Ten filters were included as controls. Amalgam produced a cons
istent cytotoxic score of 1, and the difference between amalgam and th
e other materials was statistically significant (P < 0.001). Therefore
, the antibacterial activity and cytotoxicity of the materials could b
e ranked in the following order: (IRM = IRM + 10% HAP = IRM + 20% HAP)
> amalgam.