The birth of modern Endodontic occurred with the appearance of NiTi rotary instruments on market around 1993. The reciprocal and continuous rotational tools are successive evolutions of the rotary motion techniques, which are closely associated with rapid cleaning and shaping of the root canal system. 1 A multitude of studies has been performed in the last years, substantiating their high efficiencies, studying their specific characteristics, proposing unifying theories, and testing possible countermeasures. 2,3 To date, however, the role of an instrument's motion in long-term researches has not been explicitly tested. Here the literature review was specifically interested in whether an instrument's motion patterns can affect its characteristics. To that end, we used a simple classification where both movements were categorized on the basis of dynamic properties such as cyclic fatigue, And biological properties (apical extrusion of bacteria). 4

One of the most popular current debates covered by dental associations is the comparison of the endodontics retreatment's outcome with that of the implant treatment's, taking into account the patient's best interest. With the advent of new endodontics' technologies and the struggling of implant innovations to achieve and maintain high search results rankings, Data analysts are facing more difficulties when performing meaningful cross-study comparison. Accordingly, this literature review aims to answer one of the principal questions addressed by risk-benefit analysis of two long term treatments, that is "How safe, is safe enough?"