Localization of matrix metalloproteinases (MMPs-2, 8, 9 and 20) in normal and carious dentine

Background: Dentine matrix metalloproteinases (MMPs) may participate in the destruction of dentine following demineralization by bacterial acids. This study investigated the localization of MMPs in carious dentine. Methods: Frozen sections of dentine caries were prepared without demineralization and immersed in monoclonal antibody against MMP-2, -8, -9 and -20. The sections were labelled by IgG conjugated with gold colloidal particles, and observed under FE-SEM. Labelling indexes (number of gold particles /μm 2) of outer and inner carious dentine, respectively, with and without bacterial infection, were compared with that of normal dentine. Results: MMP-2 was distributed in both carious and normal dentine; the level of MMP-2 showed no significant difference among the outer caries, inner caries, and normal dentine. The labelling indexes of MMP-8 and MMP-9 both significantly decreased at the inner carious dentine compared with the level of normal dentine, but intensified again at the outer caries region. The labelling index of MMP-20 was the highest at normal dentine. Conclusions: The localization of MMPs was visibly detected using immunogold labelling. The localization of MMP-2 showed no significant difference among the three regions, while MMP-8 and MMP-9 showed significant reduction at the inner caries layer, and MMP-20 reduced toward the outer caries. © 2009 Australian Dental Association.link_to_subscribed_fulltex

Validation of swept-source optical coherence tomography (SS-OCT) for the diagnosis of occlusal caries

Objectives: In this laboratory study, we examined the use of a swept-source optical coherence tomography (SS-OCT) as a diagnostic tool for occlusal caries. Methods: One-hundred and eleven investigation sites of occlusal fissures were selected from 62 extracted teeth and examined visually using conventional dental equipment without any magnification. SS-OCT observations were carried out on the same locations as where the conventional examination had been performed. The teeth were then sectioned using a diamond saw and directly viewed under a confocal laser scanning microscope (CLSM). Presence and extent of caries was scored in each observation and the obtained results from SS-OCT and conventional visual inspection were compared with the CLSM. The reproducibility and indices of sensitivity and specificity of SS-OCT were calculated and compared with those of the visual inspection. The results were statistically analyzed using receiver operating characteristic (ROC) curve and Spearman rank correlation test. Results: SS-OCT could clearly detect the presence of enamel demineralization lesion in a tomography image synthesized based on the backscatter signal (sensitivity = 0.98). Although the sensitivity for dentine caries of SS-OCT was over that of the visual inspection, the detection level was decreased to 0.60. When the methods were compared to the CLSM, the diagnostic accuracy of SS-OCT was better than that of the conventional visual inspection (Az values of visual inspection and SS-OCT, 0.74 versus 0.86 for enamel demineralization, 0.68 versus 0.80 for dentine caries; Spearman's correlation coefficients to CLSM; visual inspection: 0.665, SS-OCT: 0.824). Conclusions: The carious demineralization, especially in enamel, can be clearly discriminated as a highlighted area due to scattering of light matches the location of demineralized area at the base of the fissure and the results correlated well with the CLSM. © 2010 Elsevier Ltd. All rights reserved.link_to_subscribed_fulltex