MATERIALS AND METHODS: Dental pulp was obtained from twelve DT and twenty-three PT extracted from thirty-five different patients between 2002 and 2003.
All teeth were immediately fixed in 10% formalin. Twenty specimens were successively decalcified in 10% nitric acid for at least 48 hours and embedded in paraffin. To perform immunohistochemistry the remaining twelve DT were differently decalcified in EDTA solution for 12 hours after the removal of enamel with a slow-speed saw under water lubrication.
Histomorphometry was carried out on photomicrographs of the entire section stained from each specimen by means of the olympus BX-60 microscope. The quantification of odontoblastic layer extent was assessed by the odontoblastic index (OI), defined as the ratio of odontoblastic layer length to pulp chamber perimeter x 100.
Dental pulps of six DT and twenty PT were stained for anti-ssDNA, using formalin-fixed tissue sections. The apoptotic index was defined for odontoblastic layer as the ratio of ssDNA-positive odontoblast to all counted odontoblastic cells x 100.
RESULTS: Dental pulps extracted from DT are characterized by absence of odontoblastic layer and occurrence of apoptotic odontoblasts. Odontoblastic index is significantly lower in DT as compared to PT. Pro-apoptotic BAX phenotype expression on odontoblasts correlates with the occurence of numerous activated caspase-3+ odontoblasts in DT.
CONCLUSION: Histomorphometry and immunohistochemistry data confirm the lack of odontoblastic layer in dental pulps of DT in association with higher occurrence of apoptotic odontoblasts as compare to PT. Taken together our results offer a possible explanation for lower success of vital treatments on primary teeth in comparison to PT.