Presentation of gaps around endodontic access cavity restoration by phase contrast-enhanced micro-CT

  • Igor KrižnarEmail author
  • Franco Zanini
  • Aleš Fidler
Original Article



To evaluate the feasibility of synchrotron-based phase-contrast (PC) μCT for visualization of the gaps and differentiation between the gaps, restorative, and endodontic materials at the tooth-restoration interface.

Materials and methods

Standardized access cavities were prepared in human maxillary molars and subjected to materials, simulating endodontic treatment: (1) saline irrigation; (2) NaOCl and 17% EDTA irrigation; (3) same as group 2, followed by application of Ca(OH)2; and (4) same as group 2, followed by application of root canal sealer. The access cavities were cleaned and restored using an etch-and-rinse adhesive and a composite material in multilayering technique. The samples were thermocycled (1000 cycles, 5–55 °C). Synchrotron-based μCT imaging was performed obtaining absorption and PC μCT images before and after the immersion of the samples into 50% AgNO3. PC μCT images were compared to absorption μCT and conventional optical microscopy images.


PC μCT of unstained samples enabled the best visualization of gaps and differentiation of restorative and endodontic materials, contaminating the cavity surface. PC μCT revealed that AgNO3 staining leads to an overestimation of gap size due to anterograde and retrograde AgNO3 infiltration into dentinal tubules and underestimation of large gaps due to lack of AgNO3 penetration.


Synchrotron PC μCT imaging enables better visualization of gap and differentiation of materials at the tooth-restoration interface. μCT imaging with AgNO3 staining has shown certain over- and underestimations. Future research should be aimed at incorporating PC μCT imaging of unstained samples for the validation of results obtained with other methods.

Clinical significance

Contamination of cavity walls with an endodontic sealer or Ca(OH)2 leads to increased gap formation at the tooth-restoration interface.


Composite resins Dentin-bonding agents Dental leakage Microscopy Root canal filling materials Dental disinfectants 



The work was supported by the Ministry of Higher Education, Science and Technology, Republic of Slovenia, under grant P3-029.

Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest.

Ethical approval

This article does not contain any studies with human participants or animals performed by any of the authors. All procedures performed in this study were in accordance with ethical standards of the institutional research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. The use of extracted human teeth was approved by the National Medical Ethics Committee, Slovenia (no. 91/03/11).

Informed consent

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


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Copyright information

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

Authors and Affiliations

  1. 1.Faculty of Medicine, Department of Endodontics and Operative DentistryUniversity of LjubljanaLjubljanaSlovenia
  2. 2.Elettra - Sincrotrone Trieste S.C.p.ATriesteItaly
  3. 3.Department of Endodontics and Restorative DentistryUniversity Clinical CentreLjubljanaSlovenia

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