Apical debris extrusion and potential risk of endodontic flare-up: correlation with rotating and reciprocating instruments used in daily clinical practice

Aim: During the mechanical and chemical preparation of root canals with reciprocating and rotating instruments, an accidental extrusion of debris beyond the dental apex can be generated. The Nickel-Titanium instruments have drastically improved the clinical procedures and the quality of endodontic treatment. The term flare-up is commonly used to indicate a clinical condition in which pain and swelling of the oral mucosa and soft facial tissues are observed following root canal therapy of a dental element. Materials and methods: After raising the PICO question, the research was carried out following PRISMA guidelines. The search engines used were: Pubmed (Medline), EBSCO and Cochrane Library. Randomized controlled trials (RCT) and in vitro studies were included. The research focus was on articles related to the debris extrusion during root shaping with rotary and reciprocating endodontic instruments. Results: Through the application of inclusion and exclusion criteria, 17 articles were selected. The Jadad Scale was used to evaluate the quality of the papers. In the modern literature, conflicting data have emerged regarding the apical extrusion of debris using the two instrumentation techniques taken into consideration. There are no studies that analyze the possible relationship between the apical extrusion and the design of the tip shape of the endodontic instrument; the connection between shaping techniques and the appearance of flare ups should also be investigated. Conclusions: The apical extrusion of debris occurs both with the reciprocating technique and with continuous rotation instruments. Specifically, regarding the ProTaper, Mtwo, Reciproc, WaveOne and Hyflex, there are discordant results in the literature. The ProTaper Universal cause a greater extrusion, compared to the reciprocating ones, while the ProTaper Next are related with a smaller extrusion. In this condition, there is no difference between WaveOne and Reciproc. The association between flare-up and debris extrusion during the shaping phase must be demonstrated with in vivo clinical research. Further studies are needed in the future.