My once straight bottom teeth are now starting to move from overcrowding. i'm worried the 3 or 4 times i clenched my teeth when angry caused that. ?

Movement: Teeth want to erupt and to move toward the midline to compensate for the effects of our stone-aged ancestors gritty diet. If teeth are not properly aligned, they will move a little today, more tomorrow, and a lot as time goes on. Please see an Orthodontic Specialist to evaluate your malocclusion (initial exam usually free) and discuss options with you. Go sooner rather than later.

Shifting: Your teeth have shifted with age, not from the four times you clenched. Please see a local dentist regarding a retainer to prevent further movement.