Original article Changes in cell density and morphology of selected cells of the ageing human dental pulp Sulinda Daud 1 , Prabhakaran Nambiar 2 , M. Zakir Hossain 3 , Mas Rizal Ab Rahman 3 and Marina M. Bakri 3 1 Dental Faculty, Segi University College, Petaling Jaya, Malaysia; 2 Department of Diagnostic Dental Practice, Faculty of Dentistry, University of Malaya, Kuala Lumpur, Malaysia; 3 Department of Oral Biology and Biomedical Sciences, Faculty of Dentistry, University of Malaya, Kuala Lumpur, Malaysia Gerodontology 2014; doi:10.1111/ger.12154 Changes in cell density and morphology of selected cells of the ageing human dental pulp Objectives: The aim of this study was to determine the changes in cell density and morphology of selected cells of the ageing human dental pulp. Background: Changes in cell density and morphology of dental pulp cells over time may affect their capability to respond to tooth injury. Materials and methods: One hundred thirty-one extracted teeth were obtained from individuals between the ages of 6 and 80 years. The apical 1/3 of the root region was removed from all teeth prior to routine processing for producing histological slides. The histology slides were used to study the changes in cell density and morphology of selected pulp cells; odontoblasts, subodontoblasts and fibro- blasts in the crown and root regions of the dental pulp. Student’s t-test and one-way ANOVA were used for statistical analyses. Results: In all age groups, the cell density for all types of cells was found to be higher in the crown than in the root (p < 0.05). In general, the pulp cell density was found to decrease with age in both the crown and root regions. However, it was noted that the reduction of coronal odontoblasts occurred later in life (40–49 years) when compared to that of subodontoblasts or fibroblasts (30–39 years). Conclusions: The density of the coronal pulp cells reduces and these cells undergo morphological changes with ageing of individuals and this may affect the pulp’s ability to resist tooth injury. Keywords: histology, pulp, odontoblast, ageing. Accepted 15 August 2014 Introduction The age-related changes of the pulp include among others, a reduction in the pulp area con- tributed by continuous formation of dentine, 1 obliteration of the pulp canal 2 which could result in reduction in the vascular supply to the pulp, structural changes of the blood capillary vessels, 3 presence of fibrous bundles brought about by change in the distribution of collagen fibrils 4 and reduction in the pulp cell population. 5 This study focuses on the cell population of selected dental pulp cells: the odontoblasts, subodontoblasts and fibroblasts. The odontoblasts form part of an elab- orate network with the trigeminal nerve fibres and are capable of sensing physical changes in temperature and mechanical stimuli occurring on the tooth and transmitting this information to the pulp. 6–8 The odontoblast may respond to external stimuli by secreting dentine or, in the case of bac- terial invasion, it may stimulate inflammatory responses. 9,10 The ability of the odontoblast cell to carry out these various functional activities throughout life has been extensively reviewed. 11 Depending on the degree of tooth injury, odonto- blast cells may die and other undifferentiated pulp cells may be recruited to take part during the tooth repair processes. 12,13 The pulp fibroblast is responsible for the formation and turnover of the pulp extracellular matrix and plays an important role during tooth injury as it is involved during the wound healing process of the pulp tissue. 14 © 2014 John Wiley & Sons A/S and The Gerodontology Association. Published by John Wiley & Sons Ltd 1