Semi-adjustable articulator with mounted casts. An articulator is a mechanical device used in dentistry to which casts of the maxillary (upper) and mandibular (lower) teeth are fixed, reproducing recorded positions of the mandible in relation to the maxilla.
The Greek scholar Heron of Alexandria created the earliest known automatic door in the 1st century AD during the era of Roman Egypt. The first foot-sensor-activated automatic door was made in China during the reign of Emperor Yang of Sui (r. 604â618), who had one installed for his royal library.
Manufacturers offer doors in a variety of wood species. In addition to traditional stile-and-rail construction, a variety of other methods are used to manufacture wood doors. The most common type of interior door is constructed with molded (or flush) high-density fiberboard skins. These are offered in a variety of designs (re-creating the look of stile-and-rail construction).