The online version of this article (https://doi.org/10.1007/s00784-018-2654-0) contains supplementary material, which is available to authorized users.
The aim of this study was to see the effect of Er:YAG laser irradiation in dentine and compare this with its effect in enamel. The mechanism of crack propagation in dentine was emphasised and its clinical implications were discussed.
Coronal sections of sound enamel and dentine were machined to 50-μm thickness using a FEI-Helios Plasma (FIB). The specimen was irradiated for 30 s with 2.94-μm Er:YAG laser radiation in a moist environment, using a sapphire dental probe tip, with the tip positioned 2 mm away from the sample surface. One of the sections was analysed as a control and not irradiated. Samples were analysed using the Zeiss Xradia 810 Ultra, which allows high spatial resolution, nanoscale 3D imaging using X-ray computed tomography (CT).
Dentine: In the peritubular dentine, micro-cracks ran parallel to the tubules whereas in the inter-tubular region, the cracks ran orthogonal to the dentinal tubules. These cracks extended to a mean depth of approximately 10 μm below the surface. On the dentine surface, there was preferential ablation of the less mineralised intertubular dentine, and this resulted in an irregular topography associated with tubules.
Enamel: The irradiated enamel surface showed a characteristic ‘rough’ morphology suggesting some preferential ablation along certain microstructure directions. There appears to be very little subsurface damage, with the prismatic structure remaining intact.
A possible mechanism is that laser radiation is transmitted down the dentinal tubules causing micro-cracks to form in the dentinal tubule walls that tend to be limited to this region.
Crack might be a source of fracture as it represents a weak point and subsequently might lead to a failure in restorative dentistry.
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Shahmoradi M, Bertassoni LE, Elfallah HM, Swain M (2014) Fundamental structure and properties of enamel, dentin and cementum, in advances in calcium phosphate biomaterials. In: Ben-Nissan B (ed) Advances in calcium phosphate biomaterials. Springer, Berlin, pp 511–547. https://doi.org/10.1007/978-3-642-53980-0_17 CrossRef
Ţălu Ş, Contreras-Bulnes R, Morozov IA, Rodríguez-Vilchis LE, Montoya-Ayala G (2015) Surface nanomorphology of human dental enamel irradiated with an Er:YAG laser. Laser Phys 26(2):025601. https://doi.org/10.1088/1054-660X/26/2/025601 CrossRef
Earl J, Leary RK, Perrin JS, Brydson R, Harrington JP, Markowitz K, Milne SJ (2010) Characterization of dentine structure in three dimensions using fib-sem. J Microsc 240(1):1–5. https://doi.org/10.1111/j.1365-2818.2010.03396.x CrossRefPubMed
Staninec M, Meshkin N, Manesh SK, Ritchie RO, Fried D (2009) Weakening of dentin from cracks resulting from laser irradiation. Dent Mater 25(4):520–525. https://doi.org/10.1016/j.dental.2008.10.004 CrossRefPubMed
Nokhbatolfoghahaie H, Chiniforush N, Shahabi S, Monzavi A (2012) Scanning electron microscope (SEM) evaluation of tooth surface irradiated by different parameters of erbium: yttrium aluminium garnet (Er: YAG) laser. J Lasers Med Sci 3(2):51–S18. https://doi.org/10.4317/medoral.17643686 CrossRef
Forien JB, Fleck C, Cloetens P, Duda G, Fratzl P, Zolotoyabko E, Zaslansky P (2015) Compressive residual strains in mineral nanoparticles as a possible origin of enhanced crack resistance in human tooth dentin. Nano Lett 15(6):3729–3734. https://doi.org/10.1021/acs.nanolett.5b00143 CrossRefPubMed
Forien JB, Zizak I, Fleck C, Petersen A, Fratz P, Zolotoyabko E, Zaslansky P (2016) Water-mediated collagen and mineral nanoparticle interactions guide functional deformation of human tooth dentin. Chem Mater 28(10):3416–3427. https://doi.org/10.1021/acs.chemmater.6b00811 CrossRef
Lin M, Liu QD, Kim T, Xu F, Bai BF, Lu TJ (2010) A new method for characterization of thermal properties of human enamel and dentine: influence of microstructure. Infrared Phys Technol 53(6):457–463. https://doi.org/10.1016/j.infrared.2010.09.004 CrossRef
Carson JK, Lovatt SJ, Tanner DJ, Cleland AC (2005) Thermal conductivity bounds for isotropic, porous materials. Int J Heat Mass Transf 48(11):2150–2158. https://doi.org/10.1016/j.ijheatmasstransfer.2004.12.032 CrossRef
Brown W, Dewey W, Jacobs H (1970) Thermal properties of teeth. J Dent Res 49(4):752–755. https://doi.org/10.1177/00220345700490040701 CrossRefPubMed
Braden M (1964) Heat conduction in teeth and the effect of lining materials. J Dent Res 43(3):315–322. https://doi.org/10.1177/00220345640430030201 CrossRefPubMed
Craig R, Peyton F (1961) Thermal conductivity of tooth structure, dental cements, and amalgam. J Dent Res 40(3):411–418. https://doi.org/10.1177/00220345610400030501 CrossRef
Bradley RS, Lu X (2015) In situ 3D Imaging of Crack Growth in Dentin. University of Manchester. https://pdfs.semanticscholar.org/65ec/4ed63df3135c8da1fe84a91fdb51cf651ba9.pdf. Accessed 26 June 2017
Wevers M, Kerckhofs G, Pyka G, Herremans E, Van Ende A, Hendrickx R, Verstrynge E, Mariën A, Valcke E, Pareyt B. (2012). X-ray computed tomography for nondestructive testing. in International Conference on Industrial Computed Tomography. http://hdl.handle.net/2268/161701
Motamedi M, Rastegar S, and Anvari B. (1992). Thermal stress distribution in laser-irradiated hard dental tissue: implications for dental applications. Polymers Laminations and Coatings Conference TAPPI Press. https://doi.org/10.1117/12.137474
Staninec M, Meshkin N, Manesh SK, Ritchie RO, Fried D (2005) Weakening of dentin from cracks resulting from laser irradiation. Clin Implant Dent Relat Res 7(1):2S1–2S7. https://doi.org/10.1016/j.dental.2008.10.004 CrossRef
Lafrenz KA (2004) Tracing the source of the elephant and hippopotamus ivory from the 14th century BC Uluburun shipwreck: the archaeological, historical, and isotopic evidence. Dissertation, University of South Fluorida. http://scholarcommons.usf.edu/etd/1122
Lu X (2015) Characterisation of the anisotropic fracture toughness and crack-tip shielding mechanisms in elephant dentin. Dissertation, University of Manchester. https://www.research.manchester.ac.uk/portal/files/54575584/FULL_TEXT.PDF
Attrill DC, Davies RM, King TA, Dickinson MR, Blinkhorn AS (2004) Thermal effects of the Er: YAG laser on a simulated dental pulp: a quantitative evaluation of the effects of a water spray. J Dent 32(1):35–40. https://doi.org/10.1016/S0300-5712(03)00137-4 CrossRefPubMed
- Micron-scale crack propagation in laser-irradiated enamel and dentine studied with nano-CT
Thomas J. A. Slater
- Springer Berlin Heidelberg
Clinical Oral Investigations
Print ISSN: 1432-6981
Elektronische ISSN: 1436-3771
Neu im Fachgebiet Zahnmedizin
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