Which type of conditioner is designed to penetrate the cortex and temporarily reconstruct the hair shaft from within?

The type of conditioner designed to penetrate the cortex and temporarily reconstruct the hair shaft from within is a protein conditioner. Protein conditioners are specifically formulated to provide the hair with the necessary building blocks—such as amino acids and proteins—that are vital for maintaining and strengthening the hair's internal structure. When applied, they can help to fill in gaps and weaknesses in the hair's cortex, which is essential for improving the overall strength and resilience of the hair.

This type of conditioner is particularly beneficial for hair that has been damaged due to chemical treatments, heat styling, or environmental factors. By fortifying the hair from within, protein conditioners can lead to healthier-looking hair and can reduce breakage, making them an important part of a hair care regimen, especially for individuals with compromised hair integrity.