Is it normal for a baby to start teething at three months old, and what is the scope of pediatric surgery?

At 1 year and 7 months, a child has only grown 6 teeth. Could this be related to their diet?

A 14-month-old baby grew 6 teeth at 8 months, but no new teeth have emerged since. Parents inquire if this indicates a calcium deficiency.

Parents inquire about the possible reasons and treatment methods for an 8-year-old child who has not started replacing teeth yet.