Orthodontic A&h-acts and Reviews 1231

FIRST STAGE OF ERUPTION

(Migration of the Unerupted Tooth in the Jaw)

During these growth changes, a constant transformation of the bone on the inside of the maxilla and mandible takes place. Compact bone is being changed to cancellous bone, and vice versa.

What do the tooth crypts and their germs do during this period? In the maxilla, they start from under the baby orbit, and they finally lie an inch and a half below it, to say nothing of their lateral and forward movements. Evidently their speed in movement is even greater than the growth of the bone, because they start the migration above the alveolar surface (unerupted) and later on pass it (erupted).

Furthermore, if the alveolar process moves laterally through deposition of bone on its buccal and through absorption on its lingual surface, the tooth crypt, holding the unerupted tooth, would ultimately be exposed on its lingual side. As this is not the case, it must be assumed that the unerupted tooth travels in its crypt together with the bone.

SECOND STAGE OF ERUPTION

(Emergence of the Tooth Into the Mouth)

As the tooth crypts are formed at the same early age at which the tooth crown calcifies, it becomes evident that they have to travel a considerable distance before they reach their final place where the crypt ruptures and the tooth emerges. Their movement may be due to interstitial bone changes, but in all probability it is part of that process which is called eruption.

The life cycle of a tooth may, therefore, be divided in two stages: first, its development in the crypt and its journey through the jaw to the place where the crypt ruptures; second, the emergency of the tooth from the rup- tured crypt into the mouth, and its consequent further eruption.

For the eruption of the tooth into the mouth several factors have been made responsible :

(1) Elongation of the tooth root. (2) Multiplication of the pulp cells. (3) Deposition of new cement layers. (4) Gr0wt.h of the alveolar bone.

(Every one interested in the problem of tooth eruption will find in this article a new and instructive analysis of this complex phenomenon.)

E. N.

Changes in the Mouth Cavity During the Period of Menstruation. Abstracted from “die Verlnderung der Mundhohle wiihrend der Menstruation” by Dr. Anny Klein, Zahnlrztliche Rundschau, September, 1934, Berlin.

At the Women’s Clinic at the University of Erlangen, eighty women were examined for the condition of their teeth during and after the period of menstruation. About one-third of them suffered from some changes that were taking place in their mouths.

One group (20) showed signs of inflammation, namely? hyperemia of the mucous membrane, reddening. swelling. pain. stomatitis. chronic a,phthoides, and herpes labialis. In one case, a swelling of the salivary glands was noticed. which recurred periodically every four or eight weeks, during t,he time of menstruation.

Snother group (12) demonstrated changes in the periodont-al struct,ures. These were evidenced by a mobility of the teeth. by menstrual perivdont,itis, by drawing pains in healthy teeth, or bJ- regularly returning pains in teeth which had fillings. In 6 of tlrese cases. t,he pains radiated toward the ear and cranium.

The influence of menst,ruation upon t,he occurrence of caries was studied only on those women who had not yet borne children, in order to eliminate conditions which were possibly due to their previous gravidity. Among them, there were 37 who had menses only every t,wo, three, or four months. 811

examination of their mouths revealed no difference in the frequency of caries as compared to that in women who menstruated regularly every month. (This finding was contrary to the one obtained by Dr. Nessel of Viennai

On account of the above mentioned changes, it may sometimes be necrs- sary that the dentist inforrn his pat,ients of the influence which menstruation has upon the mouth, and that he postpone certain operations until. the menses are over. In t,his connection it may also be mentioned that during menstrua- tion no anesthetic should be used which contains suprarenin because the secretion of this subst,ance is already increased during the period, and a further increase may lead to collapse, spasms, headaches, and postoperative bleeding.

E. N.