Modern Endodontics is rotary endodontics by use of NiTi (Nickel-Titanium ) instruments.

Nickel-Titanium (NiTi) is :

• A "super-elastic", very flexible alloy,
• With memory: it returns to its original shape after bending or deformation,
• Very resistant to fatigue,
• Biocompatible and no corrosive.

All these qualities make it an ideal alloy for endodontics, because it is unlikely to ledge, transport or perforate even in very curved canals. NiTi allows a better distribution of forces along the whole length of the blade (elasticity); the resistance which exists with stainless steel blades disappears. The blade flows easily into the canal without catching.

At the beginning of rotary endodontics we used NiTi files similar to the manual (K-H) files you know very good, but mounted on a contra-angle and used at about 300-400 Tpm.
This was one of the reasons why many dentists saw no interest to pass to the rotary technic considering that it uses the same files that are already used in the manual technique, but costs more and are more likely to Break .

To gain in effectiveness, several manufacturers developped istruments made specifically For the ROTARY Technique .
during next threads I will talk about some of these techniques
(Principle- Instruments - Advantages - And my personal experience if I already used them) , i'll give you the best hotlinks i find too.

In the rotary technic which uses traditional files (on contra-angle) Canal Enlargement is made gradually with files (from the smaller to the bigger one ) over the FULL WORKING LENGTH like the manual technic.

In rotary technics CROWN DOWN Principels are applied طريقة Step Down لتحضير الأقنية الجذرية !! : this aims for gradually decreasing resistances in the dental canal to reduce the stress over the instruments and thus reducing the risk of fracture of instrument .

Feel free to ask me any question you want and submit any idea that can be interresting for the group

AND ALWAYS REMMEMBER :
(1) Establish a reliable working length (Electronically and/or via radiographic images)
(2) Maintain apical patency through recapitulation with smaller files
(3) Establish good canal taper to allow for better irrigation and obturation of the deeper apical portions of the canals
(4) Maintain a "mental map" of the canal system in your head through the use of sensitive files and constant subtle tactile feedback.
(5) In Endodontics the axiom of "better, easier, cheaper…pick two" is the rule

And the most important for a successful treatement :
Irrigate frequently and abundantly

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Dear Bassam, Thanks a lot for this interesting introduction, we are looking forward to get the information and the rest of your important thread in order to gain benefits and to spot the light on the unclear points concerning such Tec.
But before you get start, I got a small question bore in my mind: is there another kind of alloys (instruments) used in the rotative Mechanical techniques other than NiTi? If so, please mention

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And the most important for a successful treatement :
Irrigate frequently and abundantly

And Thanks that you stressed on this important rule

here isn't anotehr alloy to my knowledge(please correct me if you find anything else

NiTi as written is specially used for its elasticity and you clearly feel this elastisity because a niti instument can take 2 or 3 curves in the root that a normal manual file cannot take ,
One day i used NiTi files in a curved root till diameter 40 but was unable to pass a file N°30 in the same soot and had to rework the canal for some time because Gutta percha wasn't passing to my working lenght.
This was boring but without Niti instruments, canal enlargement would have taken me at least 4 hours ,with them i enlarged the 3 canals (2 of them were multi curved and joint in the apex) in about 2 hours including manual enlargement at the end......