The purpose of this study was to determine the changes that occur in the gingival microcirculation during the development of experimental gingivitis in humans. There have been no studies published to date combining videomicroscopy and laser Doppler flowmetry to study vascular dynamics in experimental gingivitis. Alterations occurring in the microcirculation of the marginal gingiva in 10 (18-30-year-old), healthy male humans when they suspended oral hygiene procedures in a proscribed area for 12-16 days were monitored. A partial mouth, experimental gingivitis model was employed. Gingival health was evaluated before and after the experimental period by assessing gingival and plaque indices and gingival crevicular fluid volume. Gingival vascular monitoring included measurement of red blood cell velocity in individual gingival microvessels via videomicroscopy and measurement of regional gingival blood flow using laser doppler flowmetry. The number of vessels visible in a given microscopic field in a given subject and the number of vessels exhibiting flow were also determined from the videotapes. Systemic cardiovascular and respiratory parameters were monitored to ensure that gingival vascular changes were not secondary to systemic changes. Gingivitis developed in all subjects; significant increases (Student t-test, p < 0.05) were seen in plaque index, gingival index, bleeding on probing and crevicular fluid volume. No change in superficial capillary blood velocity and a significant decrease in gingival regional blood flow were seen with gingivitis. A significant increase in the number of vessels visible in microscopic fields and a decrease in the % of vessels exhibiting flow were observed. Gingival microcirculation exhibited a dramatic, dynamic change in response to the development and progression of gingivitis.

There have been no published reports characterizing gingival vascular function in humans of different ages. In this study, we compared gingival vascular dynamics in 60 healthy male humans ranging in age from 18-75 years (young, 18-25 years (Y); middle, 35-45 years (M); old, 65-75 years (O), 20 subjects/group). Both videomicroscopy of individual microvessels and laser doppler flowmetry were employed to assess marginal gingival circulation. Systemic cardiopulmonary parameters were monitored as controls. The number of gingival vessels visible in a microscopic field was higher and the number of microvessels exhibiting active flow was lower in M and O compared to Y. There were no differences among age groups in laser doppler flow values (tissue blood flow) or in red blood cell velocity in individual vessels. Although not statistically significant with age there was a trend towards decreasing blood flow velocity in both the laser doppler and videomicroscopic measurements. Blood pressure increased slightly with age. Peripheral oxygen saturation was lower in O compared to Y and M. No differences were seen in heart rate, respiratory rate or end-tidal carbon dioxide concentration. The changes in blood pressure and oxygen saturation were expected. The differences in numbers of visible vessels and the number of vessels with active blood flow may reflect the way the gingival microcirculation adapts with age to changing nutritional needs or to microbial and/or mechanical challenge.

Tobacco was transplanted at the Research and Education Center, Princeton, KY, on 30 May. All tobacco was produced using standard agronomic practices, including topping on 7 Aug, harvest on 19 Sept, housing, firing, stripping, and grading. Plots were 3 rows wide by 25 ft long. Adjacent plots were separated by single untreated guard rows. Foliar application of insecticides was made to the center row using a Co2 powered back pack sprayer fitted with 3, 70° hollow cone nozzles/row with one nozzle directly over the row and with 8 inch drops (aimed 135° from vertical) on either side of the row. Treatments were applied in 29 gal/acre at 42 psi. Aphid ratings were made from 5 consecutive plants in the center of each plot, using the following rating scale. 0°no aphids present, 1°very light, 1 aphid to small colonies, 2°several colonies but not widespread, 3°general, widespread colonies, 4°extremely heavy, on all plant parts. Application of Orthene 75 SP was applied in the transplant water, by foliar application or by a combination. Thiodan 3EC was applied by foliar application. The topping time spray was made on 8 Aug. Schedule sprays were made on 26 Jul, 8 Aug, and 24 Aug. Thus, the schedule sprays included the topping time spray. Treatments were arranged in a randomized complete block design.