Abstract: A dental impression tray includes venting in the palatal area of the tray that permits excess impression material to be expelled downward and forward as the impression material and tray are forced upward against the patient's teeth when the impression is taken. At least one vent is located along the apex of the palatal shelf portion of the tray. A pressure plate is also employed which lies substantially in the plane of the base of the tray near the back of the tray. The pressure plate provides a reduced pressure against the impression material and also provides a convenient place in the center of the dental tray for the clinician to apply upward finger pressure to control the positioning and pressure of the tray against the patient's teeth as it is applied.

Abstract: A method for tracking objects is disclosed. First a region containing the objects is scanned to generate a multiplicity of sequential images or data sets of the region. A plurality of points in each of the images or data sets corresponds to a respective plurality of the objects. Next, respective figures of merit are determined for assigning the points to the tracks. Next, a k-dimensional cost function is defined which sums the figures of merit for combinations of assignments from the images or data sets. Next, the complexity of the cost function is reduced by Lagrangian Relaxation by permitting a point to be assigned to more than one track and adding a penalty factor to the cost function when a point is assigned to more than one track. The reducing step is iteratively repeated and the resultant penalized cost function is solved.