Some people have more sensitive teeth than others. why is that?

Depends: On what kind of sensitivity you are talking about. Cold sensitivity is frequently related to tooth grinding-bruxism. Hot is more common with abscessed teeth. Sweet sensitivity is because of cavities and gum recession.

Individuality: Everyone is different. Different thresholds of pain, different restorations in teeth, different gum recession, etc, etc. Many factors go into what hurts one person and not the next.

Some more than other: Yes some people will have more sensitive than others. Diet is the major cause. Most foods are acidic Do a web search to see the biggest offenders. Most tooth pastes TP are very abrasive. Use a gel or a baking soda base TP. This minimizes the abrasion affect. Use as minimal amount of TP to get the job done. About 1/2 the size of an pencil eraser tip.See you DDS for more help.