Clinical Oral Investigations

, Volume 23, Issue 2, pp 697–706 | Cite as

Both operator and heat treatment determine the centring ability of Reciproc® files in vitro

  • N. HofmannEmail author
Original Article



To determine the shaping ability of reciprocating files without/with post-manufacturing heat treatment (Reciproc®/Reciproc blue®, VDW) when used by six operators of similar level of experience.

Materials and methods

Plastic training blocs with curved root canals (5 mm radius, 55° angle) were mounted in a dental manikin. Each operator prepared six specimens with each instrument system using the file sizes R25, R40 and R50 consecutively. Specimens were photographed, and deviations from the centre of the canal were measured at intervals of 0.5 mm and averaged for the apical, middle and coronal part of the canal. Data were tested for significance using the Mann-Whitney U test and two-way ANOVA with instrument systems and operators serving as factors.


Deviations were observed towards the outer curvature in the apical and coronal and to the inner curvature in the middle segment of the canal. They were larger after using larger size instruments and were smaller when using Reciproc blue® compared to Reciproc®. Significant differences among operators were observed in the middle (all sizes) and coronal part of the canals (only sizes R25 und R40). Coronally, interaction between the main factors was significant as well.


Post-manufacturing heat treatment significantly improved shaping ability of the reciprocating file system Reciproc®. The observed differences among operators suggest the possibility of further improvement by providing specific training for prospective users.

Clinical relevance

Maintenance of root canal curvature may be improved by using post-manufacturing heat-treated instruments, but specific training should be recommended as well.


In vitro Nickel-titanium Operator effect Post-manufacturing heat treatment Reciprocating files Root canal preparation 



The author would like to thank all operators for performing the root canal preparations. The training blocs and instruments were kindly provided by the manufacturer.

Compliance with ethical standards

Conflict of interest

The author declares that he has no conflict of interest.

Ethical approval

This article does not contain any studies with human participants or animals performed by any of the authors.

Informed consent

For this type of study, formal consent is not required.

Supplementary material

784_2018_2486_MOESM1_ESM.jpg (788 kb)
Figure S1 a) Resin training blocs (Endo Trainer Block, VDW, Munich, Germany); b) Endo Training Model Castillo (VDW); c) training bloc mounted in dental manikin; facial mask omitted for better visibility d) training bloc with delineation of curvature and angulation. (JPG 787 kb)


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Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2018

Authors and Affiliations

  1. 1.Department of Operative Dentistry and PeriodontologyUniversity Hospital of WürzburgWürzburgGermany

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