Neural Regen Res, Official publication of Publishing House of Neural Regeneration Research China Association of Rehabilitation Medicine,China

The dental pulp stem cells (DPSCs) of six donors (three young donors aged < 19 years and three adult donors aged > 25 and < 30 years) were characterized for their stem cell marker expression and differentiation potential to study the effect of donor age on DPSCs in vitro. DPSCs were cultured in αMEM supplemented with 20% fetal calf serum (conventional conditions) or on fibronectin-coated flasks with neurobasal medium supplemented with B27, bFGF and EGF (alternative conditions). DPSCs were characterized by immunofluorescence staining to detect the neural crest/mesenchymal stem cells markers P75 and CD146, respectively. The differentiation potential was tested by the induction of DPSCs into osteogenic, adipogenic and glial lineages and then by detecting the corresponding markers osteocalcin, lipidtox and S100ß, respectively. The DPSCs of the young donors expressed CD146 only under the conventional conditions and expressed P75 regardless of the culture conditions. However, the DPSCs of adult donors expressed CD146 only under the alternative conditions and expressed P75 only under conventional conditions. Only the DPSCs of the young donors differentiated into the glial linage. The DPSCs of the adult donors differentiated more efficiently into the adipogenic linage. Osteogenic differentiation was comparable. Donor age affects the expression of stem cell markers and differentiation potential of DPSCs. Moreover, the effect of culture conditions on DPSCs is age dependent.

Estimation of age-at-death is an integral part of the identification process of individuals in many forensic odontology cases where their identity cannot be determined by visualization or other ways. Dental age estimation in the adult is more challenging as most of the dentition is completely developed by 18 years of age. This study employs a mesio-distal (MD) pulp-to-tooth ratio taken at the neck of lower third molars (LM3) to provide an estimation of age at the time of radiographic imaging based on the well-known fact that pulp volume tends to decrease with advancing age due to continued apposition of secondary dentine throughout adulthood. A total of 155 Conebeam computed tomography (CBCT) radiographs of LM3s for a random sample of 155 Jordanian Arabs (80 females, 75 males; age range= 18-58 years, mean age= 28.2 years, SD =10.0 years) were used. Both pulp and tooth MD diameters were measured at the neck. MD pulp-totooth ratios for LM3s were linearly regressed against age. Statistically significant negative association was found between an individual's age at the time of imaging and the MD pulp-to-tooth ratio taken at the neck. Specifically, the strength of the association is r=-0.361, which means only 13.0 % of the variation in age can be explained by the MD pulp-to-tooth ratio taken at the neck. Therefore, it was concluded that MD pulp-to-tooth ratio taken at the neck of LM3s is not a reliable predictor of chronological age in adults, possibly due to the large variation in the timing of LM3 development.