Int Poster J Dent Oral Med 2003, Vol 5 No 04, Poster 199
The Effect of Fluoride Release from a Bonding Material on Nanoleakage
Priv.-Doz. Dr. Thomas Pioch, Dr. Marcus Wurst, Prof. Dr. Dr. Hans Jörg Staehle, Priv.-Doz. Dr. Christof Dörfer
Poliklinik für Zahnerhaltungskunde der Mund-, Zahn- und Kieferklinik des Universitätsklinikums Heidelberg
Prof. Dr. Heinz Duschner
Institut für Angewandte Struktur- und Mikroanalytik der Universität Mainz
25th - 28th September 2002
European Festival of Oral Science, PEF
Cardiff, Wales, UK
The so called "nanoleakage" is located within the hybrid layer at the dentin composite interface. The term has been introduced by Sano et al. in 1995 to characterize penetration pathways within hybrid layers of dentin-composite interfaces in the absence of gap formations. This phenomenon is reported in the literature to hamper dentin bonding. Remineralization of etched dentin due to fluoride release from bonding agents might affect the nanoleakage pattern.
To evaluate the effect on nanoleakage formation by a fluoride releasing dentin bonding material over time.
Material and Methods
Standardized class-V cavities were prepared in 60 extracted human molars. 30 cavities were filled with composite (Spectrum) using the Prime&Bond NT bonding system (containing cetylamine hydrofluoride). 30 teeth were filled with the same composite and an experimental Prime&Bond NT without fluoride additives. Prior to the microscopic studies 15 teeth per group were stored for 24 h in water and the remaining 15 teeth per group were stored for 6 months in water. After storage the teeth were soaked in a 1% rhodamine B dye solution (24 h, 20 °C), rinsed in water for 60 s and sectioned parallel to the tooth axis, dividing the restorations into two parts. Confocal laser scanning microscopy (CLSM) was used to visualize a layer 10 µm below the prepared surface. The morphology of the dentin composite interfaces were visualized at high magnification in fluorescent mode. The lengths of the penetrated pathways were measured at low magnification using an overlay of images recorded either in reflection or overmodulated fluorescent mode.
|Fig. 1: Scheme of the penetration pathways between dentin and composite.
||Fig. 2: Low magnification CLSM image of dye penetration with over modulated fluorescence signal.
E = embedding material.
High resolution CLSM images demonstrate penetration pathways located at the interface between hybrid layer and dentin. No differences between fluoride releasing material and the material without fluoride can be detected (see Figs. 3A and 3B). Storage for 24 h resulted in penetration lengths of 53 ± 59 µm. After 6 months the penetration lengths are 74 ± 40 µm for the fluoride releasing bonding agent and 75 ± 52 µm for the experimental bond without fluoride content. After storage for 6 months dye penetration slightly increases, but the difference is not statistically significant (p=0.09 fluoride releasing material and p=0.11 material without fluoride; Mann-Withney U-test).
|Fig. 3A: High magnification CLSM image of dye penetration after long term storage (fluoride releasing material).
||Fig. 3B: High magnification CLSM image of dye penetration after long term storage (no fluoride releasing material).
||Measured nanoleakage short term storage
||Measured nanoleakage long term storage
|Prime & Bond NT
||53 ± 59
||74 ± 40
|Prime & Bond NT nf
||53 ± 59
||75 ± 52
|Tab. 1 Measured extension of dye penetration: nf=non fluorid.
It is concluded that the penetrations observed are a result of nanoleakage. Fluoride release or a 6 months storage has no statistically significant effect on nanoleakage.
This Poster was submitted by Priv.-Doz. Dr. Thomas Pioch.
Priv.-Doz. Dr. Thomas Pioch
Poliklinik für Zahnerhaltungskunde
der Mund-, Zahn- und Kieferklinik
des Universitätsklinikums Heidelberg
Im Neuenheimer Feld 400