Thermodontic stimulator--a new technology for assessment of thermal dentinal hypersensitivity.

A clinical investigation of the reproducibility of threshold and pain temperature scores obtained from use of the Thermodontic Stimulator (TDS) is reported. The TDS is designed for accurate clinical testing of thermal dentinal hypersensitivity. This instrument employs a variable stimulus/fixed response approach to clinical testing of thermal dentinal hypersensitivity. The TDS consists of a probe in a handpiece, a patient signaling device (joystick), a computer, and interface electronics. The TDS provides a precise means of assessing and recording the temperature which elicits a response to thermal stimulation from the subject being evaluated. Two temperatures are recorded. The threshold temperature is recorded when the patient is first able to sense that a cold stimulus has been applied to the tooth. The second score, pain temperature, is recorded when the subject first notices discomfort. Twenty-two subjects participated in this study. Results obtained from the 21 subjects who completed this study (one subject dropped out for non-compliance) demonstrated a reproducibility standard deviation of 1.1 degrees C for the threshold temperature, and 2.8 degrees C for the pain temperature for the duration of the study. There was a good degree of correlation between the measurements of any two test days (Pearson's correlation coefficient). There was no significant difference between the mean pain temperature scores of any two testing days.

Accuracy testing of three-dimensional digitizing systems.

An accuracy test designed as a standard for digital occlusal wear measurement devices was applied to such a device designed by the authors. The test was used for quantitative determination of measurement error for a given angle of tangential contact with the inclined planes of the surface being measured. Using known dimensions of the digitizer contact tip and of a precision steel sphere, we determined trigonometrically the error in the Z-axis measurement due to the slope of any point on the surface of the sphere. These values were used for a point-by-point correction of data obtained from actual digitization of the sphere. The corrected values would equal zero if no mechanical source of error existed. These values, then, quantitatively indicated the accuracy (in microns) of the device as a function of the slope of the measurement point. The results indicated a linear relationship between surface slope angle and measurement error for the device tested.