d e n t a l m a t e r i a l s 2 9 ( 2 0 1 3 ) 382–388 Available online at www.sciencedirect.com jo ur n al homep age : w ww.intl.elsevierhealth.com/journals/dema Examination of ceramic restorative material interfacial debonding using acoustic emission and optical coherence tomography Chun-Li Lin a,* , Wen-Chuan Kuo b,1 , Jin-Jie Yu a,2 , Shao-Fu Huang a,2 a Department of Biomedical Engineering, National Yang-Ming University, No. 155, Sec. 2, Linong Street, Taipei 112, Taiwan b Institute of Biophotonics, National Yang-Ming University, No. 155, Sec. 2, Linong Street, Taipei 112, Taiwan a r t i c l e i n f o Article history: Received 12 August 2012 Received in revised form 23 October 2012 Accepted 14 December 2012 Keywords: Acoustic emission Optical coherence tomography Fatigue Ceramic Dentin a b s t r a c t Objective. CAD/CAM ceramic restorative material is routinely bonded to tooth substrates using adhesive cement. This study investigates micro-crack growth and damage in the ceramic/dentin adhesive interface under fatigue shear testing monitored using the acoustic emission (AE) technique with optical coherence tomography (OCT). Methods. Ceramic/dentin adhesive samples were prepared to measure the shear bond strength (SBS) under static load. Fatigue shear testing was performed using a modified ISO14801 method. Loads in the fatigue tests were applied at 80%, 70%, and 60% of the SBS to monitor interface debonding. The AE technique was used to detect micro-crack signals in static and fatigue shear bond tests. Results. The results showed that the average SBS value in the static tests was 10.61 ± 2.23 MPa (mean ± standard deviation). The average number of fatigue cycles in which ceramic/dentin interface damage was detected in 80%, 70% and 60% of the SBS were 152, 1962 and 9646, respectively. The acoustic behavior varied according to the applied load level. Events were emitted during 60% and 70% fatigue tests. A good correlation was observed between crack location in OCT images and the number of AE signal hits. Significance. The AE technique and OCT images employed in this study could potentially be used as a pre-clinical assessment tool to determine the integrity of cemented load bearing restored ceramic material. Sustainable cyclic load stresses in ceramic/dentin-bonded spec- imens were substantially lower than the measured SBS. Predicted S–N curve showed that the maximum endured load was 4.18 MPa passing 10 6 fatigue cyclic. © 2012 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved. 1. Introduction With advances in adhesive methods and ceramic mate- rials, adhesive restorations are advantageous because the macro-retentive design is no longer a prerequisite if an ∗ Corresponding author. Tel.: +886 2 28267000x7039; fax: +886 2 28210847. E-mail addresses: cllin2@ym.edu.tw (C.-L. Lin), wckuo@ym.edu.tw (W.-C. Kuo), e198402019@yahoo.com.tw (J.-J. Yu), shaofu.h@gmail.com (S.-F. Huang). 1 Tel.: +886 2 28267950. 2 Tel.: +886 2 28267000x5405; fax: +886 2 28210847. adequate amount of tooth surface is available for bonding. Clinicians are particularly interested in restoring minimal or absent macro-retentive preparations with extensive dentin- or enamel-bonded ceramic coverage [1]. Increased demand in recent years for esthetic and metal-free restorations has 0109-5641/$ – see front matter © 2012 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.dental.2012.12.003