Odontoblast processes of the mouse incisor are plates oriented in the direction of growth

Abstract

Odontoblast processes are thin cytoplasmic projections that extend from the cell body at the periphery of the pulp toward the dentin-enamel junction. The odontoblast processes function in the secretion, assembly and mineralization of dentin during development, participate in mechanosensation, and aid in dentin repair in mature teeth. Because they are small and densely arranged, their three-dimensional organization is not well documented. To gain further insight into how odontoblast processes contribute to odontogenesis, we used serial section electron microscopy and three-dimensional reconstructions to examine these processes in the predentin region of mouse molars and incisors. In molars, the odontoblast processes are tubular with a diameter of 1.8 μm. The odontoblast processes near the incisor tip are similarly shaped, but those midway between the tip and apex are shaped like plates. The plates are radially aligned and longitudinally oriented with respect to the growth axis of the incisor. The thickness of the plates is approximately the same as the diameter of molar odontoblast processes. The plates have an irregular edge; the average ratio of width (midway in the predentin) to thickness is 2.3 on the labial side and 3.6 on the lingual side. The plate geometry seems likely to be related to the continuous growth of the incisor and may provide a clue as to the mechanisms by which the odontoblast processes are involved in tooth development.

The Development of Dentin Microstructure Is Controlled by the Type of Adjacent Epithelium

“…( 18 , 19 , 37 ) However, only a limited number of research studies focus on the morphology of the dentinal tubules and their functional components—odontoblast processes. ( 14 , 36 , 38 ) Using DSPP Cerulean /DMP1 Cherry mouse strain, we were able to map the three‐dimensional morphology of odontoblast processes in an unprecedented detail. First, we described a significantly different OPs morphology within the crown and roots of mouse molars.…”

Activin receptor-like kinase 3: a critical modulator of development and function of mineralized tissues

“…Odontoblasts are mesenchyme-derived cells, with cell bodies arranged in the dentin wall proximal to the pulp. Their protrusions extend into the dentin tubules to the enamel-dentinal junction (Shuhaibar et al, 2021). In addition to forming dentin, odontoblasts sense nociceptive pain (Wen et al, 2017) and cold stimuli (Tazawa et al, 2017), act as surveillance cells to detect invading pathogens and trigger immune responses (Yumoto et al, 2018).…”