Volumetry of ovine incisors dental pulp for further regenerative therapy

Abstract

Mesenchymal stem cells (MSCs) are used for regenerative therapy. Dental pulp MSCs make extracted wisdom teeth a useful resource in humans. Preclinical validation of regenerative therapies requires large animal models such as the sheep. Since stem cells can be retrieved from the dental pulp of ovine incisors, the best age to extract a maximal volume of dental pulp needs to be defined. The objective of this ex vivo study was to quantify incisors dental pulp volume, in sheep of various age. Three jaws were dedicated to histology (one per age group); the others were imaged with a computed tomography scanner [3 years-old (n = 9), 4 (n = 3) and 6 (n = 5)]. The incisors dental pulp volume was measured after 3D reconstruction. Multiple linear regression showed that dental pulp volume of ovine incisors decreases with age (beta-estimate = -3.3; p < 0.0001) and teeth position from the more central to the more lateral (beta-estimate = -4.9; p = 0.0009). Weight was not a relevant variable in the regression model. The dental pulp volume ranged from 36.7 to 19.6 mm3 in 3-year-old sheep, from 23.6 to 11.3 in 4-year-old sheep, and from 19.4 to 11.5 in 6-year-old sheep. The pulp volume of the most central teeth (first intermediate) was significantly higher than the most lateral teeth (corner). Haematoxylin-Eosin-Safran of the whole incisors, and of isolated dental pulps demonstrated a similar morphology to that in humans. The first intermediate incisor of 3-year-old sheep should be selected preferentially in preclinical research to retrieve the highest volume of dental pulp.