In vitro mineralization by pulp cells

Objectives: The aim of this study was the identification and quantitative analysis of the in vitro mineralization by pulp cells depending on root formation and chemical stimulation. Methods: Pulp cells of 7 human caries-free freshly extracted third molars with incomplete or complete root formation were separately cultured. Each cell culture was divided into 6 groups on the basis of the presence of the following chemical additives in medium: calcium hydroxide (CH) 1,7mg/ml, ß-glycerophosphate (GP) 3µg/ml, ascorbic acid (AA) 50µg/ml (table). The scanning electron microscope analysis of mineralized areas on inserted culture discs were carried out 25 days after application of chemical additives. X-ray microanalysis was used to investigate the composition of the mineralized nodules. The differences between the quantitative mineralization in groups without and with chemical additives to the medium were statistically analysed with repeated measures variance analysis and Dunett tests (global a=0.05). Results:

Groups	n	Mineralized nodules per mm2 Mean ± SD	Significance
1   Control	7	0.79±0.54
2   CH and GP	7	1.19±0.83	n.s.  (p=0.97)
3   CH	7	2.37±1.99	n.s.  (p=0.11)
4   GP and AA	7	2.66±0.71	s.     (p=0.04)
5   GP	7	1.06±1.29	n.s.  (p=0.99)
6   AA	7	2.47±2.23	n.s.  (p=0.08)
Root formation incomplete Root formation complete	24 18	1.47±1.40 2.14±1.66	n.s.  (p=0.31)

s. - significant difference      n.s. - no significant difference

X-ray microanalysis of the mineralized areas showed that the pulp fibroblasts produced a high amount of calcium and phosphorus. The most mineralized nodules were found in group 4, followed by groups 6 and 3 (table). There was statistically significant difference between group 1 and group 4 only. Conclusions: The mineralizing activity of dental pulp fibroblasts was dependent on chemical stimulation, but independent of root development.