Title Motor Driven Instrumentation Causes Dentinal Cracking
Clinical Question In teeth being endodntically treated, do motor driven instrumentation systems, compared to nickel titanium hand files, cause more dentinal cracks?
Clinical Bottom Line Nickel titanium rotary instruments, whether reciprocating or continuous rotation, cause more dentinal defects (complete and incomplete cracks) than k-flex files.
Best Evidence  
PubMed ID Author / Year Patient Group Study type
(level of evidence)
23228272 Liu/2013240 extracted mandibular incisorsLaboratory study
Key resultsTwo hundred and forty single canaled mandibular incisors were embedded in resin with a layer of VPS to act as a PDL space. The teeth were instrumented with Flex K files, ProTaper, and K3 according to manufacturers directions. The K3 (P=0.021) and ProTaper (P=0.015) files caused significantly more cracks than hand files.
23522545Burklein/2013100 freshly extracted mandibular central incisorsLaboratory study
Key resultsOne hundred single canaled mandibular incisors were divided into 5 groups: Mtwo, ProTaper, Reciproc, WaveOne, and control. In the apical section, Reciproc and WaveOne caused more cracks compared with Mtwo and Protaper (P=0.001).
23880276Liu/2013100 extracted mandibular incisorsLaboratory study
Key resultsOne hundred mandibular incisors with straight roots were divided into 5 groups: Reciproc, SAF, OneShape, ProTaper, and Control. Reciproc and SAF caused fewer cracks than the ProTaper and OneShape (P<0.001).
Evidence Search "Apical Cracks"[MeSH], "Endodontics"[MeSH], "Dentinal Defects"[Mesh}
Comments on
The Evidence
Several studies have now established that instrumentation with rotary instruments, whether continuous rotation or reciprocating motion, results in dentinal cracks in the apical portions of the roots. In the current studies, Liu, et.al., created a simulated PDL space to more accurately mimic actual treatment conditions, where Burklein held the teeth while instrumenting. This may have effected Burklein's results. While it accepted that apical cracks are occurring, it is unclear whether there is a clinical significance to these cracks. It is speculated that bacteria could colonize the cracks causing residual infection. It is also speculated that the apical cracks could propagate into vertical root fractures resulting in tooth loss. Now that it is well established that these dentinal defects are being caused by instrumentation with motor driven systems, more research needs to be done to determine the clinical significance.
Applicability Endodontic treatment relies on effective chemo-mechanical instrumentation of the root canal system. Endodontists and general dentists performing root canal therapy need to be aware of the potential harm from some file systems.
Specialty (Endodontics) (General Dentistry)
Keywords Apical Cracks, Root Crack, Single –File System, Rotary Instrument
ID# 2712
Date of submission 04/06/2014
E-mail ethelyn_thomasonlarsen@ucdenver.edu
Author Ethelyn Thomason, DMD
Co-author(s) e-mail
Faculty mentor
Faculty mentor e-mail
Basic Science Rationale
(Mechanisms that may account for and/or explain the clinical question, i.e. is the answer to the clinical question consistent with basic biological, physical and/or behavioral science principles, laws and research?)
None available
Comments and Evidence-Based Updates on the CAT
None available