Effects of non-painful and painful mechanical stimulations of tooth and gingiva on the gingival blood flow were studied by using a laser Doppler flowmeter in ten healthy subjects.
The findings obtained were as follows:
1. Repetitive mechanical stimulation of tooth and gingiva produced an increase in the gingival blood flow. Painful stimulation elicited a marked flow increase. Sub-painful stimulation also induced a less marked but constant increase in the blood flow. The response was abolished after local anaesthesia at the stimulated site.
2. The threshold of stimulation for the upper central incisor was 0.3-1.8 kg. The corresponding values for the labial gingiva and palatal mucosa were 100-370 g/cm² and 220-410g/cm², respectively.
3. The increase in the gingival blood flow elicited by the ipsilateral stimulation was greater than that elicited by the contralateral stimulation. Contrary to painful stimulation, non-painful stimulation of tooth and gingiva induced no increase in the cutaneous blood flow of the cheek and hand.
4. Gingival blood flow increased following voluntary rhythmic biting of an acrylic resin block and chewing of a dried cuttlefish.
These results suggest that a mechanical stimulation of tooth and gingiva during oral functions such as mastication may induce an increase in the gingival blood flow.