Hi! It is perfectly fine. Eruption time of primary or baby teeth varies from child to child. A baby's first tooth usually appears sometime between four months and the infant's first birthday. Some children are born with teeth and others do not develop them until they are well over one year old. You should give it a few more months and allow time for his teeth to erupt. If your son is two years old and no teeth have appeared, x-rays may be easier to obtain and will be more accurate.