Abstract: A dental chair assembly comprises a base, a support, a first pivot mount and a second pivot mount. The support is configured to support a chair seat defined to extend in a forward direction and a chair back positioned rearward of the chair seat. The support has a forward side, an opposite rearward side and a longitudinal axis extending through the forward and rearward sides. The first pivot mount is positioned along the longitudinal axis forward of the rear side of the support and configured to support at least one movable arm. The first pivot mount defines a first upright pivot axis. The second pivot mount is positioned along the longitudinal axis and spaced forwardly from the first pivot mount. The second pivot mount is configured to support at least one movable arm and defines a second upright pivot axis parallel to the first upright pivot axis.

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 dental chair assembly comprises a base, a support, a first pivot mount and a second pivot mount. The support is configured to support a chair seat defined to extend in a forward direction and a chair back positioned rearward of the chair seat. The support has a forward side, an opposite rearward side and a longitudinal axis extending through the forward and rearward sides. The first pivot mount is positioned along the longitudinal axis forward of the rear side of the support and configured to support at least one movable arm. The first pivot mount defines a first upright pivot axis. The second pivot mount is positioned along the longitudinal axis and spaced forwardly from the first pivot mount. The second pivot mount is configured to support at least one movable arm and defines a second upright pivot axis parallel to the first upright pivot axis.

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.