Stimulated whole saliva samples were collected from 30 healthy individuals and analysed with a cone and plate viscometer. On the basis of these dynamic viscosity measurements saliva from patients, who represented the mean value and two standard deviations above and below the mean value, were selected for frictional force testing. Four archwire/bracket couples (SS/SS, SS/PCA, ~-Ti/SS, and I3-Ti/PCA) were each tested in these three salivas as well as in the dry state a total of five times, each at five different normal loads. With two exceptions no significant differences were found between any of the three wet states for any couple studied. When the dry state was compared to any of the wet states, the SS archwire couples showed a singificant increase in frictional forces, while the 13-Ti archwire couples showed a slight decrease in frictional forces, which was not statistically significant.

Complications during or shortly after mandibular midline distraction surgery are relatively rare and mostly mild or transient. Only 3% of the patients presented irreversible damage. Thus, mandibular midline distraction appears to be a relatively safe method of expanding the mandible.

The dynamic viscosity (t~) of stimulated whole saliVa in a typical pre-orthodontic sample population was characterized as a function of temperature (T). Samples were collected from 30 adolescents or young adults, after screening for factors that are known to have an effect on salivary viscosity. Using a cone and plate viscometer, 1.5 ml of stimulated whole saliva was evaluated at a constant shear rate of 450s -1 from T=20°C to T= 40°C. Data from the I~-T plots showed a negative dependence of the form, p = a-bT, over a range of I~ from 1.08 to 2.45 centipoise (cps) at 34 °C. Most of the samples fell into a narrow envelope, where the mean I~ of the saliva samples ranged from 2.42+0.61 cps at 20°C to 1.57_+0.32 cps at 37°C. With regard to sample stability, viscosity-time plots indicated that a small but predictable decrease in t~ occurred during the 3 h period. The i~-Tplots generated from fresh and frozen saliva samples demonstrated an appreciable change in p as a result of refrigeration. With regard to sample reproducibility, viscometric data obtained from a typical pre-orthodontic patient over a 1-week period fluctuated within a fairly broad envelope of values.