Abstract: A positive positioning device comprises a plurality of stacked plates, a body, a spring-biased piston and a piston release device. The plurality of stacked plates have a central opening defined to receive a pivot shaft. The body houses the plurality of stacked plates and has an internal bore within which a cylinder is defined. The spring-biased piston is shaped to slide within the bore to apply a force to the stacked plates to resist rotation of a pivot shaft inserted through the central opening in the stacked plates. The piston release device is actuatable by a user to release the piston to decrease force applied to the stacked plates and allow free rotation of the pivot shaft.

Abstract: A positive positioning device comprises a plurality of stacked plates, a body, a spring-biased piston and a piston release device. The plurality of stacked plates have a central opening defined to receive a pivot shaft. The body houses the plurality of stacked plates and has an internal bore within which a cylinder is defined. The spring-biased piston is shaped to slide within the bore to apply a force to the stacked plates to resist rotation of a pivot shaft inserted through the central opening in the stacked plates. The piston release device is actuatable by a user to release the piston to decrease force applied to the stacked plates and allow free rotation of the pivot shaft.

Abstract: Described herein are various embodiments of a dental delivery system. For example, in one exemplary embodiment, a rear dental delivery system through which at least one of water, air and vacuum are delivered for use by a care giver in treating a patient occupying a nearby dental chair can include at least one movable arm that is pivotably mounted to a pivot connection and an upright mounted to the at least one movable arm. The pivot connection can be mounted at approximately a floor level and the at least one movable arm can be configured to pivot slightly above the floor level so as to reduce obstruction in a space separating the dental chair from the dental delivery system.

Abstract: An expandable stop ring slides over the end of a top post until it engages a selected one of a number of spaced apart grooves in the end of a top post. The end of the top post is inserted into a bottom tubular post until the stop ring fits inside a keeper that is mounted to the upper end of the bottom post. The keeper prevents expansion of the stop ring, hence the stop ring and keeper combination support the top post and any equipment carried thereon. The top post height adjustment is made by lifting the top post to remove the stop ring from the keeper, thereby permitting sliding movement of the stop ring to another selected groove on the top post.

Abstract: The mask has a cap from which two deformable legs protrude. The legs are deformed to permit the outermost parts of the legs to be snapped into a groove in the socket that carries the lamp of the dental light. The mask is not attached to a reflector shield, thereby simplifying the manufacture of the overall lamp.