What is observed 1mm below the DEJ in cavity preparation?

At a depth of 1mm below the dentin-enamel junction (DEJ) in cavity preparation, the correct observation is that there are some dentinal tubules present, along with more intertubular dentin and less peritubular dentin.

This is due to the structural composition of dentin as it progresses from the DEJ towards the pulp chamber. Near the DEJ, the density of dentinal tubules is relatively high, but as you move deeper, particularly at the 1mm mark, there is a shift in the ratio of intertubular to peritubular dentin. Intertubular dentin, which makes up the bulk of dentin and is less mineralized than peritubular dentin, appears more abundantly at this depth.

Peritubular dentin, found around the tubules, tends to be more concentrated closer to the DEJ. As you go deeper, there’s a decrease in peritubular dentin, which supports the statement about the relative proportions of dentin types. This arrangement is crucial for understanding the biomechanics of dentin and its properties during cavity preparation, influencing how dental materials bond to and interact with the tooth structure.