[Study of apical diffusion of three different kinds of calcium hydroxide preparations in vitro]

To investigate the diffusion effect of calcium hydroxide in periapical simulation of the diffusion model.

Pipetman pipette tips, plastic syringes and BHI agar were prepared to be periapical simulation of the diffusion model. 120 simulation models were divided into three groups. Group 1: 100 microl 20% calcium hydroxide suspension were sealed in pipette tips; group 2: 100 microl 90% calcium hydroxide cataplasm were sealed in; group 3: 100 microl calcium hydroxide points were sealed in. By different apical aperture (15#,25#,40#,80#), each group was divided into four subgroups (each subgroup contained 10). Preparation of 12 other simulation models sealed with distilled water were as a control. pH values and Ca(2+) concentration were measured by PH analyzer and calcium analyzer respectively. The data was collected to establish a database, using SPSS13.0 software package, randomized block design ANOVA was performed.

The average pH value (8.26, S=0.86) of group 1 was significantly higher than that in group 2 (7.96, S=0.702) and Group 3 (7.83, S=0.59) (P<0.05), but no significant difference was found between group 2 and group 3. The average calcium concentration of group 1 (29.87 ppm. S=10.76) was significantly higher than that in group 2 (24.62 ppm. S=10.40) and group 3(16.42 ppm, S=5.70). There were significant differences among the three groups (P<0.05). The results also showed that the average pH value and the average calcium concentration were increased with apical aperture. There were significant differences between each group (P<0.05).

The diffusion effect of calcium hydroxide suspension in periapical simulation of the diffusion model is better than calcium hydroxide cataplasm and calcium hydroxide points; the diffusion effect is also proportional to the apical aperture. Supported by Key Research Project of Science and Technology Bureau of Sichuan Province (Grant No.05SG022-007).