• Pravej Serichetaphongse D.D.S., M.Sc.
• Watcharaporn Tasachan D.D.S., M.Sc.
• Supparaporn Kantasuwan B.Sc.
• Pasutha Thunyakitpisal D.D.S., Ph.D.

Objective To investigate the antimicrobial activity of aluminium chloride against Streptococcus mutans
and Aggregatibacter actinomycetemcomitans, in vitro.

Materials and methods An inhibitory activity was determined by using broth dilution technique and
time kill method. S. mutans and A. actinomycetemcomitans were grown in tryptic soy broth and brain
heart infusion, respectively. Both organisms were treated with different concentrations of aluminium
chloride [0.05, 0.1, 0.2, 0.3, 0.4 and 0.5% (w/v)] at 37 ÌC, 5% CO2 for 0.5, 3, 6, 9, 18 and 24 hours.
Their survivals were evaluated in comparison to the control using drop plate method.

Results The minimum inhibitory concentration (MIC) of S. mutans and A. actinomycetemcomitans
were 0.2 and 0.05% (w/v), respectively. While the minimum bactericidal concentration (MBC) of
S. mutans and A. actinomycetemcomitans were 0.5 and 0.2% (w/v), respectively. At the concentration
of 0.5% (w/v) aluminium chloride, S. mutans survival was declined to zero at 3-hour incubation.
A. actinomycetemcomitans survival was declined to zero in 9-hour incubation with 0.2% (w/v)
aluminium chloride.

Conclusion Aluminium chloride, at 0.5 and 0.2% (w/v), revealed the bactericidal activities against
S. mutans and A. actinomycetemcomitans, respectively. Aluminium chloride, at 0.2 and 0.05% (w/v),
had inhibitory activity against S. mutans and A. actinomycetemcomitans, respectively.

(CU Dent J. 2008;31:399-406)