Early Cellular Reactions in Mechanically Stimulated Gingival Connective Tissue

Abstract

The results question the role of macrophages at the early stages of gingival remodeling incident to mechanical stimulation.

Effects of mechanical stimulation on cell cycle duration in rat gingival fibroblast progenitor cells

“…Calculation of 3 H‐TdR‐labelling indices under experimental conditions identical to those of the present investigation (11) reveals that recruitment of new cells from gingival progenitor cell populations is one of the earliest cellular events of tissue remodelling, occurring far more rapidly than cell division in wounded gingiva (9). It is manifest as conspicuous proliferative bursts both in the tissue area immediately coronal to the interdental bone crest between 1–24 h, 72 h and 168 h after the onset of mechanical stimulation and in the central zone of the papillary body within 12–24 h and after 72 h of stimulation.…”

“…Subjective examination revealed that in the material of the present study the bands remained in situ for 5 d followed by loss of the bands and cessation of tooth movement thereafter. As well as having the virtue of simplicity, this experimental model ensures sufficiently prolonged mechanical stimulation of the interdental gingival papilla to induce cellular reactions which may manifest themselves over the entire experimental period (11).…”

“…The gingival tissue compartments coronal to the interdental bone crest and in the central zone of the papillary body which were chosen for 3 H‐TdR‐labelled cell sampling, include areas known to be rich in fibroblast progenitor cells (4). These cells show the rapid and conspicuous increase of proliferative activity in response to mechanical stimulation (11) which is an attribute of progenitor cells (18). Classification of 3 H‐TdR‐labelled cells was accomplished on the basis of the results of earlier studies, which have shown that early gingival fibroblast progenitor cells are resident in paravascular sites, and their progeny migrate into extravascular tissue domains (6, 7).…”

“…Recent investigations of the reaction of these cells to the mechanical stimulation of experimental tooth movement showed that these progenitors residing in the immediate vicinity of junctional epithelium can sustain homeostatic levels of proliferative activity, indicating stability of local cell populations during orthodontic tooth movement (10). In contrast, fibroblast progenitors located immediately coronal to the interdental bone crest and in the central zone of the papillary body under the same conditions showed a rapidly occurring conspicuous increase in cell proliferation manifesting itself as early as 1 h after the onset of mechanical stimulation (11).…”

“…Possible explanation of such an early temporal proliferative response to mechanical stimulation is that early cell recruitment into the proliferative pool depends on switching cells in G 0 or possibly G 1 arrest back into cycle (11). However, no precise information is currently available regarding cell cycle times of gingival connective tissue cells.…”