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.
Pre-Hung vs. Slab Doors. Prehung doors include both the door and the frame that supports the door, while slab doors include just the door alone. Tip: If your slab door is more than 25 years old, itâs best to go with a pre-hung door to ensure a sealed frame. Slab Doors. â¢ Good choice if only the door needs to be replaced.