Vascular Responses in the Human Periodontal Ligament and Alveolar Bone Detected by Photoelectric Plethysmography: The Effect of Force Application to the Tooth

Abstract

A modification of the technique of photoelectric plethysmography has been developed to monitor changes in the microcirculation of the human periodontal ligament and adjacent alveolar bone, whereby detection is made of light reflected from or transmitted through a tissue during alterations in blood volume, flow or distribution. Light is conducted to and from the periodontal tissues via miniature fiberoptics placed within the root canals of endodontically treated teeth, or illuminated through the external surface of the gingiva towards the root. Circulatory activity was monitored both with the teeth at rest and under forces up to 480 gm. Horizontal and axial forces were found to produce a decrease in blood volume in the area of the periodontal tissue under compression. In an area under tension, an initial increase in blood volume was followed by a decrease as the magnitude of force rose above the critical 90 to 180 gm level. The pulse volume, however, was increased during both phases. Analysis of the biphasic and pulse volume changes suggests that autoregulation of blood vessel tone occurs in the periodontal tissues as a result of alteration in extravascular tissue pressure when the root is moved relative to the alveolus. It is proposed that this autoregulatory mechanism may play a role in alveolar bone metabolism by producing alteration in local tissue oxygen tension.

Laser Doppler Blood-Flow Signals from Human Teeth during an Alignment and Leveling Movement Using a Superelastic Archwire

“…Above this range, the observed response was an initial increase in blood volume followed (immediately or after few seconds) by a decreased blood volume [17]. In a later study in rat's incisors, using vital microscopy, ischemic areas in both compressed and tensioned zones in the PDL were observed, beginning in capillaries and venules in response to 0.03 N and ending with arterioles (0.1 N).…”

Cell kinetics of the initial response to orthodontically induced osteogenesis in rat molar periodontal ligament

“…Further studies of particularly vascular changes during the initial period following application of force are indicated. Within seconds following application of 90-180 g of force [19], photoelectric plethysmography revealed a decrease in vascular volume in areas of periodontium subjected to tension. Consequently, the drop in labeled cells, at 15 min in the present study, may be secondary to a reflex vasoconstriction associated with the tooth support mechanism.…”

Altered distribution of HMGB1 in the periodontal ligament of periostin-deficient mice subjected to Waldo’s orthodontic tooth movement

“…Less stretch is reasonably associated with less tensile force in PDL of tension side and less increase of HMGB1 expression compared with WT mice. However, the additional promotive effect of periostin deficiency on HMGB1 production makes up for it, leading to a comparable HMGB1 expression level to WT mice Primary, tension of the PDL alters blood vessel morphology and the vascular response in the alveolar socket (Kuitert et al 1988;Noda et al 2009), leading to a reduction in blood volume (Packman et al 1977), which can eventually induce local hypoxia and apoptosis in PDL cells (Rygh 1973). Both hypoxia-caused cell injury and apoptosis of cells are well recognized as stimulators for HMGB1 expression and release (Andersson et al 2002;Bianchi 2007;Wang et al 1999).…”