First, Between the fourth and eighth months of life the two lower front middle teeth appear almost simultaneously; then a pause of from three to nine weeks ensues.
Second, Between the eighth and tenth months of life the five upper front teeth appear, following shortly upon each other, the two central preceding the two on each side of them. Another pause of from six to twelve weeks succeeds.
Third, Between the twelfth and sixteenth months of life six teeth appear nearly at once. They are first the two front grinding teeth in the upper jaw, leaving a space between them and the front teeth which before appeared; next the two lower front teeth, situated one on each side of the central ones, which were the first to appear; and, lastly, the two front grinders of the lower jaw. A pause until the eighteenth month now ensues.
Fourth, Between the eighteenth and twenty-fourth months of life the canine teeth cut through (the upper ones are called eye-teeth). Again a pause until the thirtieth month.
Fifth, Between the thirtieth and thirty-sixth months the second four grinders finally make their appearance.
This concludes the first teething. The child has now twenty milk-teeth.
We have mentioned that children are sometimes born with teeth. It is also true that sometimes they never acquire any. Instances are on record of adults who have never cut any teeth. Dentition has been known to take place very late in life. A case is related, on excellent authority, of an old lady aged eighty-five, who cut several teeth after attaining that age.
APPEARANCE OF THE PERMANENT TEETH.
Between the fifth and sixth years of life the second dentition begins. The front grinders are the ones first cut through. Between the sixth and tenth years all the front teeth appear, followed by the canines before the twelfth year. At this time the second grinders show themselves; and finally, between the sixteenth and twenty-fourth year, the wisdom-teeth complete the dental furniture of the mouth.