Combined with proper home care and regular dental visits, sealants are extremely effective in preventing tooth decay. They will also potentially save you a lot of time in a dental chair later on, if your teeth start to require fillings, crowns, or even root canals.
The average age is 12, but this does not mean that all girls start at the same age. A girl can start her period anytime between the ages of eight and 15. Usually, the first period starts about two years after breasts first start to grow. If a girl has not had her first period by age 15, or if it has been more than two to three years since breast growth started, she should see a doctor.
So, the chart below gives the events and their ranges. The average age for periods in the U.S. is 12.16 for black girls and 12.88 for whites. By age 11, 28% of black girls and 13.5% of whites menstruate. By age 12, 62% of blacks, and 35% of whites. A girl's first menstruation is called menarche.