Expression of proliferating cell nuclear antigen in pulp cells of extracted immature teeth preserved in two different storage media.

A specially composed medium for storing avulsed teeth has been developed. In experimental and clinical studies it could be shown that PDL cells could be kept viable during storage in the medium for up to 53 h. In the present study the medium was tested on pulp cells. A total of 40 immature unerupted third molars with open apices were removed surgically and the teeth were stored in a special cell culture medium (SCCM) or in Hank's balanced salt solution (HBSS) at room temperature for 6, 12, 18 or 24 h. Five teeth were assigned to each group. A total of seven consecutive pulp cross-sections per tooth were examined, resulting in a total of 280 specimens. Viable cells were marked using proliferating cell nuclear antigen (PCNA). The pulp was divided in three regions: apical region (0-0.5 mm), middle region (>0.5-1.5 mm) and coronal region (>1.5 mm). The labelling index (LI) was calculated for the whole cut (regions 1, 2 and 3) and for each region separately. The statistical evaluation was made using the One-way anova and Mann-Whitney Test. Pulp cells of all teeth expressed PCNA. About 110 of 140 specimens in the SCCM and 101 of 140 specimens in the HBSS group showed PCNA-positive cells. The highest LI was observed within the apical region and decreased with increased distance from the medium. No marked cells were observed at a distance of more than 1.5 mm. The LI for both media showed a significant increase with storage intervals (P < 0.05). The pulp cells of teeth stored in SCCM showed a LI nearly twice as high compared to pulp cells of teeth stored in HBSS for the apical and middle region (time interval 6, 18 and 24 h: P < 0.05). The LI for the apical region was found to be 8.43% for the SCCM and 4.50% for the HBSS after 24 h. For the middle region the LI was found to be 2.02% for the SCCM and 0.81% for the HBSS after 24 h. Within the parameters of this study, it appears that the SCCM is able to maintain pulp cell viability better than HBSS. The use of special cell culture media in case of tooth avulsion may be beneficial.