Histological Aspects of Human Enamel Fissure Caries studied by CLSM

K E Y W O R D S dentistry, enamel, fissure caries, confocal laser scanning microscopy, tomography, microradiography, acid fuchsin A C K N O W L E D G E M E N T S Thanks to Mr Y. Ito and Dr K. Masuno for their collaboration in the elaboration of histological slides and to Mr J. Fujita for his collaboration with English translation. A U T H O R D E TA I L S Dr T. Nishikawa, Department of Oral Pathology, Osaka Dental University, 8-1, Kuzuhahanazono-cyo, Hirakata, Osaka 573-1121, Japan. Tel: +81 72 864 3057 Fax: +81 72 864 3157 Email: [email protected] Microscopy and Analysis (UK), 93, 23-25, 2003. ©2003 Rolston Gordon Communications. rods, with carious cones having bases on the dentine sides. These carious lesions had a series of zones from outside to inside: surface zone, body of the lesion, dark zone, and translucent zone [4] (Fig 1). Microradiography The surface zone and the translucent zone were radio-opaque, the body of the lesion and the dark zone showed various degree of radiolucency and accentuation of the striae of Retzius existed in the radiolucent areas (Fig 2). CLSM All enamel caries were brighter than normal enamel, which did not fluoresce, whether the 535 nm ( em) filter (green) or 590 nm ( em) filter (red) was used. The area of altered enamel identified by CLSM was more clearly identified than that apparent by light microscopy or microradiography. The surface zone had yellow fluorescence with the 535 nm and 590 nm filters together. The surface side of the bodies of the lesions had red fluorescence with the 590 nm filter but appeared black viewed with the 535 nm filter; the striae of Retzius and the dark zones were yellow with the 535 nm and 590 nm filters simultaneously. The translucent zones displayed dark green fluorescence with the 535 nm filter alone and green or yellow fluorescence with the 535 nm and 590 nm filters together (Fig 3). The CLSM image analysis of carious lesions observed with the 590 nm filter alone was performed to assess colour-graded fluorescence intensity. The lesions progressed along the peripheral portion of the enamel rod-like structures, with strong intensity in the surface zone. In the surface side of the body of the lesion, the prismatic structure of the enamel was lost (Fig 4). Tomographic images taken at 5 μm depth intervals by CLSM at this site demonstrated that the lesions were approximately spheroid instead of flare-shaped (twin cone-shaped) as seen by other techniques (Figs 5 and 6) [5]. Changes in enamel and rod structure in the body of the lesions At high magnification CLSM with image analysis using the 590 nm filter alone, intense fluorescence was seen in almost the entire body of the lesion. The outside of the body of the lesions indicated followed two fluorescent patterns: one in which fluorescence was present along the central portion of the enamel rods, and the second at their periphery (Fig 7). Observation of enamel lamella-like structures, aprismatic zones Enamel lamella-like structures extending from the tooth surface to the dentino-enamel junction were apparent at some peripheral portions of the enamel rods by CLSM. The enamel Histological Aspects of Human Enamel Fissure Caries studied by CLSM T. Nishikawa, S. Yoshida, A. Tanaka, H. Zoellner 2 and D. M. Walker 2 1. Dept of Oral Pathology, Osaka Dental University, Japan. 2. Dept of Oral Pathology, Faculty of Dentistry, Univ of Sydney, Australia P23-24-25 NISHIKAWA 30/12/02 2:39 pm Page 1