Root canal instrumentation using purely hand instruments often represents a quite laborious and “boring” task, fraught with unavoidable problems.
As early as 1899, William H. Rollins developed the first hand-piece for engine-driven instrumentation of root canals. The first commercially available handpieces allowed only limited motion in terms of speed and direction. In subsequent years, several improved systems were introduced to the marketplace. As well as combining rotary and up-and-down motion of the file, a special feature of these motors was their ability to respond to an increase in resistance caused by the instrument becoming wedged within the root canal. A clutch mechanism would change the motion of the instrument as soon as friction within the root canal increased, intended to reduce the danger of instrument fracture. However, owing to the use of stainless-steel instruments with these hand-pieces, the consequences very often included ledge formation, perforation, or even instrument fracture.
With regard to engine-driven root canal instrumentation, the “classic” systems have virtually no role today. This is because of the numerous mechanical nickel-titanium (NiTi) instruments that are now available and demonstrate high cleaning efficiency and intracanal effectiveness.
The Racer system, introduced in the 1950s, was the first endodontic handpiece for engine-driven root canal instrumentation that gained a significant market advantage. It allowed a purely vertical motion. However, there were frequent reports of instruments becoming wedged in the root canal, and even instrument fracture.
The development of the rotatory motor led to improved canal instrumentation. The Giromatic system, introduced in 1964, was widely accepted and used. Its reciprocal 90° rotatory motion made possible rapid and simple root canal instrumentation. This instrument motion within the canal was also adopted by other systems. The Endolift M4 motion had a smaller rotational component of 30°. The vertical motion of the handpiece could be controlled by clinicians themselves.
With the introduction of the Endolift (Kerr), a system became available on the commercial market that combined vertical with a reciprocal 90° rotary motion. Later Kerr sought to improve the rigid vertical motion by incorporating a more flexible-type motion. The Excalibur system combined for the first time aleatoric oscillations with a variable-amplitude vertical motion.