Enamel, which covers the anatomical crown of the tooth, is the hardest tissue in human body. Supported by a soft but tough dentin structure, the tooth is an advanced nanocomposite that can endure mastication stresses throughout a lifetime. A detail understanding the structure of the tooth, and sepecifically detin-enamel junction (DEJ), not only provides a sound basis for a model for synthetic dental restoration, but also provides lessons from nature on biomimetic regeneration with mechanical integrity. Enamel is a non-growing mineralized tissue and is subjected to most mechanical abuse. Dentin-enamel junction plays a critical role of distributing load between two very dissimilar materials - enamel and dentin. Bulk scale mechanical tests have shown that induced cracks on enamel tend to be arrested DEJ. Furthermore, nanoindentation measurements have also shown that there is a gradual decrease in hardness from enamel to dentin in the DEJ zone suggests a strong mechanical coupling in both deciduous and adult incisors. The objective of this investigation, through microscopical study, is to understand how these two dental hard tissues structurally couple through their junction zone.