Evaluation of enamel prisms surrounding enamel lamellae - histomorphometric studies

Studies conducted till now suggest that enamel lamellae may exert a protective role for enamel prisms and, following lamellae degradation, they may provide potential pathway for progression of demineralization processes. Objectives: Present study aimed at determination of manifestation frequency, localization and metric dimensions of lamellae and the enamel surrounding them in erupted permanent human teeth. Methods: The material included 51 premolars and 53 molars, extracted for orthodontic purposes in 18-30-year-old generally healthy patients. The teeth were cut along their long axes. The total of 764 sections were obtained, which were stained using H+E and Mallory's techniques. Computer-assisted histomorphometric analysis was performed employing Nikon Eclipse E600 light microscope and the MicroImage 4.0 software. The data were subjected to statistic analysis. Results: In both groups the highest average numerical force of enamel lamellae, calculated per tooth crown cross-section was noted in the region below approximal surface while in the remaining regions it was more than twofold lower. Enamel lamellae widths manifested high variability while values of their lengths were definitely lower (by 122.52% and 85.94%, respectively). Values of Spearman's rank correlation index for correlation of enamel lamellae length with enamel lamellae width amounted to r_s=0.47 for premolar teeth and to r_s=0.18 for molar teeth. Using U Mann-Whitney's test significant differences were noted between length of enamel lamellae in the two groups of teeth. Moderate positive correlations were demonstrated between length of enamel lamellae and area of full demineralization in premolar teeth (r_s=0.57) and in molar teeth (r_s=0.54). Nevertheless, values of Spearman's rank correlation index prevailed in 68.75% of studied relationships, pointing to absence of correlation between the studied histomorphometric traits and lamellae parameters. Conclusion: The histomorphometric results demonstrated that enamel lamellae are related to regions of enamel demineralization and, thus, enamel lamellae represent one of variables that promote spreading of caries.