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.
Doors can be constructed of many different materials, from the common wood door to the newer UPVC and fibreglass models which are currently finding their way into homes across Australia. Getting the choice right for the material, especially on exterior facing doors like the front entryway, is critical for the longevity and appearance of the door.