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.
1 A six-panel pine door costs about $500-$600, while decorative exterior wood doors or a custom exterior door, made from mahogany or cherry with options like glass, transoms and sidelights, could cost as much as $2,000 to $5,000 or more. Wood is the most popular choice for an exterior front door. 2  An exterior wood door made of wood veneer and engineered wood costs around $200 to $500. 3  Solid wood doors are more expensive.