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Class I malocclusion, with pronounced anterior open-bite, induced by constant finger-sucking, in a monkey
CLASS I MALOCCLUSION, WITH PRONOUNCED ANTERIOR OPEN-BITE, INDUCED BY CONSTANT FINGERSUCKING, IN A MONKEY HARRY E. KELSEY, D.D.S., F.A.C.D., BALTIMORE, MD. H E rhesus monkey from which these illustrations were secured was one of a large number under observation at the Carnegie Laboratory of Embryology at the Johns Hopkins University. Dr. John Marshall, during his research on tissue changes in monkeys incident to tooth movement for the American Society of Orthodontists, visited the Carnegie Laboratory where his attention was called to this monkey by Dr. Carl Hartman of the staff; and he suggested that Dr. Hartman communicate with me in regard to it, believing an orthodontist would be interested in such a case, providing as it does collateral evidence on the subject of thumb-and finger-sucking habits. I, personally, and also the members of the Society are thus indebted both to Dr. Hartman and to Dr. Marshall for the evidence presented. When I arranged to go to the laboratory to see this monkey I expected that we would have to hide and keep very quiet in order to catch her sucking her finger. My apprehensions were quite groundless. The monkey presented no timidity or embarrassment regarding her habit, as children sometimes do, and the only time I saw her without the finger being in her mouth was when she was running around the cage or the runways. The moment she stopped, she would immediately stick the left forefinger into her mouth, as can be seen in Fig. 3, where she is sucking her finger while hanging on to the wire grill forming one side of the runway. After regaining consciousness from the ether (which had to be administered in order to get impressions) this was also her first voluntary act. We know, of course, that this or any other habit indulged in constantly by a child will have a marked effect upon the form and development of the structures involved. This case is to me gratifying collateral evidence of this fact. The monkey, a female about four and a half years old, had indulged in this habit since or even before weaning. I regret I have no motion picture of this case. I fully intended to get it but was assured by Dr. Henry Klein that he could and would get it, which he did, but apparently forgot to give a copy of it to Dr. Hartman and it has been impossible to get it in time for this presentation. Dr. Klein and Dr. Kyrle W. Preis (my associate at the time) aided me, along with Dr. Hartman and his assistants, in securing the impressions. The first attempt was made without an anesthetic and proved futile. While not apparently a vicious animal, this monkey disliked above all else having observations made upon her teeth and in her mouth, a characteristic of all animals, including the human. The second attempt was made after an administration of avertin,
T
Read before the American Society of Orthodontists, St. Louis, April 20-22, 1936.
1119
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Harry E. Kelsey
and while the monkey was exceedingly sleepy and quite indifferent to general handling, she roused up and vigorously resisted impression making. Ether was thereupon administered, and the impressions were then made without much difficulty. She appeared to suffer no ill effects from the anesthetic, notwithstanding the fact that she had had some food within several hours previous to the ether administration.
Fig. 1.
Fig. 2.
To construct impression trays I used the model of a child's maxillary arch, sawing it apart and then trimming off a good sized segment from the medial margin, putting the two halves together again and trimming up the teeth somewhat. This made a model quite similar to the monkey's maxillary arch upon which trays were adapted of vacuum material, and mandibular trays were then constructed to match them approximately. Impressions were made with an
Class I }Ialocclusion Induced by F inger-Sucking
1121
clastic compound whi ch gives very good copies of under cuts. Of several taken, th e best were preserv ed and several duplicates mad e. When Dr. Kl ein left Baltimore to accept a r esearch position at Yal e, he requested permission of Dr. Hartman to take th e monkey with him, which was granted, and later Dr. Kl ein took her to Detroit wher e Dr. Samuel Lewis seems to have made some observ ations with him upon her. She died soon after this and it is possibl e that further inter esting data, toget her with the movin g picture. may be presented at some fu ture time, if it seems worth while. The photographs were made by eit her Dr. H artman or his assistants at the Carnegie Laboratory of Embryology at the J ohns Hopkins Univ ersity. Fig. 1 is a close up , f ull fac e, and profile of t he mouth, illustrating clearly the bending upward of th e premaxillary alveolar process and teeth, and the
Fig. 3.
bending down of th e mandibular alveolar process an d anterior teeth. In the full face view, th e alm ost circ ular aperture leadin g into the mouth while th e teeth are closed can be noted. Fig. 2 shows views of th e models. The picture shown in F ig. 3 was taken while t he monkey was clin ging to t he side of the cag e with her tw o feet and right hand, and shows the exact t echni c employed by her in sucking her IHt forefinger. In conclusion, this case seems to me to offer additional evid ence that the advi ce sometimes given (even by doctors of all kinds ) th at thumb- and flnger-sucking habits do no harm, is a pernicious evasion of the truth, because while it is true that such habits indulged in over a short p eriod will do little, if any , harm, they are rarely voluntarily discontinued, and except in th e rarest instances when the
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Harry E. Kelsey
habit IS indulged in only at intervals, invariably produce malformations in the dental arches. There is, of course, a marked difference in the response of different individuals both to habit distortions and to orthodontic treatment, but in the end normal bone yields to pressure. 833
PARK AVENUE
DISCUSSION
Dr. Samuel J. Lewis, Detroit.-I am sorry that I did not know about the movie film of the finger-sucking monkey, as I made a copy from the original film and have it on :file at the University of Detroit. I shall be pleased to loan it to Dr. Kelsey any time he wishes to show it, and I can assure you it is a most interesting record. This monkey was brought to my attention by Dr. Klein shortly after Dr. Kelsey made his observations and records, and I suggested that some means be employed either to break the habit or to prevent further indulgence. I thought we might see a self-correction of the malocclusion as we sometimes do in human beings. However, all methods but one failed, and before that could be tried for a long enough period, the monkey contracted miliary tuberculosis and died. Since seeing this monkey, two others which also sucked their fingers were sent to me from the Yale University Laboratories. While the malocclusions were not so pronounced as in Dr. Kelsey's case, there was a decided anterior protrusion and open-bite, such as we all see in our human patients. In one case the right fingers were sucked and the displacement was toward the right. In view of this evidence presented by Dr. Kelsey, and that which I presented in 1929, there is no doubt but that linger-sucking habits do alter the arch form and tooth position if indulged in over a protracted period. I concur most heartily in Dr. Kelsey's conclusions.
T
Read before the American Society of Orthodontists, St. Louis, April 20-22, 1936.
1119
1120
Harry E. Kelsey
and while the monkey was exceedingly sleepy and quite indifferent to general handling, she roused up and vigorously resisted impression making. Ether was thereupon administered, and the impressions were then made without much difficulty. She appeared to suffer no ill effects from the anesthetic, notwithstanding the fact that she had had some food within several hours previous to the ether administration.
Fig. 1.
Fig. 2.
To construct impression trays I used the model of a child's maxillary arch, sawing it apart and then trimming off a good sized segment from the medial margin, putting the two halves together again and trimming up the teeth somewhat. This made a model quite similar to the monkey's maxillary arch upon which trays were adapted of vacuum material, and mandibular trays were then constructed to match them approximately. Impressions were made with an
Class I }Ialocclusion Induced by F inger-Sucking
1121
clastic compound whi ch gives very good copies of under cuts. Of several taken, th e best were preserv ed and several duplicates mad e. When Dr. Kl ein left Baltimore to accept a r esearch position at Yal e, he requested permission of Dr. Hartman to take th e monkey with him, which was granted, and later Dr. Kl ein took her to Detroit wher e Dr. Samuel Lewis seems to have made some observ ations with him upon her. She died soon after this and it is possibl e that further inter esting data, toget her with the movin g picture. may be presented at some fu ture time, if it seems worth while. The photographs were made by eit her Dr. H artman or his assistants at the Carnegie Laboratory of Embryology at the J ohns Hopkins Univ ersity. Fig. 1 is a close up , f ull fac e, and profile of t he mouth, illustrating clearly the bending upward of th e premaxillary alveolar process and teeth, and the
Fig. 3.
bending down of th e mandibular alveolar process an d anterior teeth. In the full face view, th e alm ost circ ular aperture leadin g into the mouth while th e teeth are closed can be noted. Fig. 2 shows views of th e models. The picture shown in F ig. 3 was taken while t he monkey was clin ging to t he side of the cag e with her tw o feet and right hand, and shows the exact t echni c employed by her in sucking her IHt forefinger. In conclusion, this case seems to me to offer additional evid ence that the advi ce sometimes given (even by doctors of all kinds ) th at thumb- and flnger-sucking habits do no harm, is a pernicious evasion of the truth, because while it is true that such habits indulged in over a short p eriod will do little, if any , harm, they are rarely voluntarily discontinued, and except in th e rarest instances when the
1122
Harry E. Kelsey
habit IS indulged in only at intervals, invariably produce malformations in the dental arches. There is, of course, a marked difference in the response of different individuals both to habit distortions and to orthodontic treatment, but in the end normal bone yields to pressure. 833
PARK AVENUE
DISCUSSION
Dr. Samuel J. Lewis, Detroit.-I am sorry that I did not know about the movie film of the finger-sucking monkey, as I made a copy from the original film and have it on :file at the University of Detroit. I shall be pleased to loan it to Dr. Kelsey any time he wishes to show it, and I can assure you it is a most interesting record. This monkey was brought to my attention by Dr. Klein shortly after Dr. Kelsey made his observations and records, and I suggested that some means be employed either to break the habit or to prevent further indulgence. I thought we might see a self-correction of the malocclusion as we sometimes do in human beings. However, all methods but one failed, and before that could be tried for a long enough period, the monkey contracted miliary tuberculosis and died. Since seeing this monkey, two others which also sucked their fingers were sent to me from the Yale University Laboratories. While the malocclusions were not so pronounced as in Dr. Kelsey's case, there was a decided anterior protrusion and open-bite, such as we all see in our human patients. In one case the right fingers were sucked and the displacement was toward the right. In view of this evidence presented by Dr. Kelsey, and that which I presented in 1929, there is no doubt but that linger-sucking habits do alter the arch form and tooth position if indulged in over a protracted period. I concur most heartily in Dr. Kelsey's conclusions.