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The Effects of the Loss of the First Permanent Molar*
IÉÉ
THE JOURNAL O F THE
American Dental Association V ol . 14
NOVEMBER, 1927
No. 11
Original Communications THE EFFECTS OF THE LOSS OF THE FIRST PERMANENT MOLAR* B y B U R N E O . S IP P Y , B .S ., D .D .S ., M .S ., Chicago, Illinois
a review o f the scientific literature INinarticles medical and dental journals, many are found treating either
directly or indirectly the problems in volving the first permanent molar in the development o f the human denture. At the present time, conflicting theories exist among orthodontists, den tists and physicians with reference to the scientific value o f the first permanent molar in its relation to occlusion and to the management of malocclusion. These theories have had their influence on the dental profession as exemplified in articles and discussions published. A summary o f the review o f the literature may be made by saying that the authors are about equally divided * R e ad b e fo re th e Illin o is S tate Society, P e o ria , 111., M a y 10, 1927.
D e n ta l
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in favor o f and against the extraction of the first permanent molars, with a smaller group who are more conserva tive, taking an intermediate position, namely, extraction irj some instances and not in others. Those in favor o f extraction claim that it relieves the crowded condition o f the teeth in the arches, the second molars moving forward to take the place of the first molars and the third molars taking the place of the second molars, and thus the denture is greatly improved; also that this procedure is much the easiest and quickest way to obtain the desired result. Those in favor o f preserving the first permanent molar whenever possible point out its importance in the develop ment of the face and jaws, and its
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effects in producing and maintaining occlusion. The conservative group are not so ready to extract first permanent molars unless the molars are in a very bad con dition, or unless the shape o f the face seems to indicate that the extraction w ill not show its effect. Some of this group would, in arches having crowded teeth, extract the bicuspids rather than the first molar, to relieve the crowding and improve the denture. The advocates o f extraction either of the first molar or the bicuspid differ as to how far to carry the plan. Some would extract only one tooth; some ad vise the extraction o f the same tooth on both sides o f the arch; while others advise the removal o f all four corre sponding teeth, if any are to be lost, to relieve the crowded arches, on the premise that the least amount o f damage w ill be done to the denture by such a procedure. There is no trend o f interest either for or against the extraction o f the first molar in the literature from 1856 to the present time. Considering the liter ature chronologically, the proportion of arguments for and against is about equal. Most o f the statements in the articles and discussions reviewed have been made on the basis of experience in individual practice extending over a period o f years, without data or sys tematic study o f effects. Such opinions are not always logical or correct, nor are they clearly expressed. At least one exception is an article by Frederick B. Noyes (1 9 2 2 ) which includes photo graphs, orthodontia casts of the jaws and case histories of patients presented in the article. In order to determine which o f the before' mentioned groups are sound in their advice, I determined to make a
study o f the problem upon a scientific basis involving dentures which had had time to show the effects o f first molar loss, and thereby eliminate the “hear say” element. Orthodontia models were made from impressions o f mouths o f a group of about 400 individuals, from 18 to 30 years o f age. This collection was be gun at the orthodontia clinic o f the University o f Illinois, College of D en tistry, in 1918. The mouths represented by this group had received the ordinary dental care but no orthodontic manage ment. There are no case histories accompanying the models and no photo graphs or radiograms. Therefore, the models were studied all the more care fully and the selection and classification of a model was made only when it presented unquestionable conditions. This cut down the number o f models available very materially. One hun dred models which showed a loss of the first permanent molar were selected, and were classified in several ways in order to determine in what manner they could be studied best. The 100 models were finally grouped. The number falling in each group is shown in Table 1. T
able
G ro u p 4 3 2 1 2 1 2
1.— G r o u p in g
of
M
odels
S t u d ie d N o.
first m o la rs m is s in g _____________________ 6 first m o lars m issin g ______________________ 12 u p p e r first m o la rs m issing------------------------ 1 u p p e r first m o la r m issin g -------------------------- 10 lo w e r first m o la rs m issing-_______________ 31 lo w e r first m o la r m issin g ------------------------30 first m o lars m issing in opposite sides an d opposite arches __________________________ 10
The individual models of each group were then studied to determine the re lation of the loss of the first permanent
S iffy — Effects o f Loss o f First Permanent M olar molar to the occlusion. It is quite obvious that the time allowed for this paper w ill not permit of a detailed de scription o f the findings in each model or even in each group o f models. The manuscript and tables covering this part o f the research work covers twenty or more typewritten pages. A summary of the findings in all groups is presented in Table 2. T able N o. o f M o d e ls 80 6 14 29 15 18 38 68 32 64 36 15 85 118 23 43 21
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mesial occlusion and 14 per cent have distal occlusion. No study has been recorded as to the relationship of arch conformation to malocclusion in any series of dentures as far as I know. In this study it is found that 38 per cent have arches ap parently not affected in length and width; 29 per cent have narrow arches; 15 per cent have short arches, and 18
2.— S u m m a r y o f
A l l G roups*
C o n d itio n S how n
N o rm a l m esio d istal re la tio n o f the arches M e sial o cclusion o f the arches D ista l o cclusion o f th e arches N a r ro w arch es S h o rt arches N a r ro w a n d sh o rt arches L e n g th a n d w id th o f archcs a p p a re n tly n o t affected M a lp o sitio n o f teeth L ittle d istu rb an ce in m a stic a tin g efficiency F irs t p e rm a n e n t m o la rs m issing o n ly , e x c e p tin g th ird m o lars F irs t p e rm a n e n t m o la rs an d o th e r teeth m issing T w e n ty -o n e b rid g es N o a rtific ia l re sto ra tio n o f the m issing first p e rm a n e n t m o la rs Spaces p a r tly closed, 44 by tip p in g , 41 by d r if tin g , 33 b y tip p in g an d d r if t in g Spaces p a r tly closed, 6 by tip p in g , 8 by d r if tin g , 9 by tip p in g a n d d r if t in g Spaces m a in ta in e d by b rid g e w o rk o r occlusion Spaces d ev elo p ed betw een o th e r teeth in th e d e n tu re , a re su lt o f th e loss o f first p e rm a n e n t m o lars
*O ne h u n d re d m o d els re p re se n tin g 184 m issing first m o lars.
re c a p itu la tio n
o f fin d in g s
The proportion o f malocclusion belonging to each class o f malocclusion has been given as about 70 per cent having normal mesiodistal relation o f the arches, 4 per cent having mesial occlusion and 26 per cent having distal occlusion. In the study o f the 100 models, it is recorded in the summary of findings that the malocclusion follows about the same proportion: 80 per cent have normal mesiodistal relation o f the arches, 6 per cent have
per cent have short and narrow arches. Therefore, 62 per cent have been affected in length and width. This would seem to be a large percentage, a much larger percentage than would be expected in a group o f 100 models showing malocclusion. This high percentage o f undersized arches is due to the collapse o f the arches or failure o f normal development o f the arches because of the loss of the first permanent molars, It is found that 68 per cent o f the dentures show malposition o f teeth. A
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large percentage o f this group have very serious malpositions o f teeth as none were recorded as such unless o f a serious nature. The percentage o f den tures showing little disturbance in mas ticating efficiency is 32. It is a natural conclusion that the percentage o f malposed teeth has not been reduced by the loss o f the first permanent molars, and the crowding o f teeth, so-called, has not been relieved. As there are no records available as to the proportion being considered, it is difficult to draw comparisons, but it would seem that the percentage o f dentures having serious malpositions is relatively high consider ing all classes o f malocclusion. O f the dentures studied, 64 per cent have lost one or more first permanent molars, excepting the third molars; 36 per cent o f these dentures have other teeth missing in addition to the first molars; 61 per cent have one or both lower first molars missing without the absence o f either upper first molar; 89 per cent have lost one or both lower first molars with the absence o f one or both upper first molars. Only 11 per cent o f the 100 dentures have lost one or both upper first molars without the loss of either lower first molar. The high percentage o f lower first molar extractions is significant. It is evident that the first molar is the one tooth in the denture which has been the prey of the extracting forceps, and particularly the lower first permanent molar. No artificial restorations o f the miss ing first molars by dental bridges was found in 85 per cent o f the dentures. Only 15 per cent o f the dentures have bridgework. This represents twentyone bridges o f a possible 184. This is a surprisingly low percentage o f restora tions, and it accounts for many o f the complications in the malocclusion of
most o f the dentures. In the forty-three first molar spaces maintained, only twenty-one bridges are a factor, the re maining twenty-two spaces being main tained by the normal influences of occlusion or because o f the fact that the extractions have been recent, sufficient time not having elapsed to determine whether or not the influences w ill con tinue to maintain these spaces. O f the 118 spaces partly closed, in forty-four this condition has resulted from the tipping of adjacent teeth, which changes the long axis of these teeth. T he partial closure of thirty-three spaces o f lost first molars has resulted from the tipping and drifting of adja cent teeth; therefore, 77 o f the 118 spaces have partly closed as a resultof the tipping o f adjacent teeth. A tremendous additional and abnormal strain is placed on the peridental membrane attached to these teeth, and as clinical evidence shows that this supporting tissue has its limits o f endurance to punishment, a large number of these teeth w ill be lost at an early age, in addition to the now missing first molars. The partial closure of forty-one spaces by bodily drifting in the bone o f adjacent teeth without changing of their long axis does not influence the peridental membrane par ticularly, but a normal dental bridge cannot be placed. An undersized bridge may be constructed that is neither effi cient nor satisfactory. Considering in the same manner the twenty-three spaces o f the missing first molar that are closed, it is found that six are closed by tipping o f adjacent teeth, eight by drifting and nine by tipping and drifting. Fifteen o f the twenty-three spaces, therefore, have been closed by the changing o f the long axis o f the adjacent teeth, and addi tional and abnormal occlusal strain has
Sifipy— Effects o f Loss o f First Perm anent M olar been placed on their peridental mem brane. As contacts have been established in this group, this strain is not so serious as in the previous group, and these teeth have the support o f their adjacent fel lows by contact. O f the dentures studied, 21 per cent show spaces between teeth an terior to the missing molars. This has occurred by the tipping and drifting distally o f the six anterior teeth and the bicuspids. (Figs. 3-5.)
F ig . 1.— O cclusion j n o r m a l re la tio n o f the in clin ed p lan es w h en th e ja w s a re closed.
Figure 1 shows the normal relation of the inclined planes o f the teeth when the jaws are closed; namely, occlusion. It also shows, by the india ink markings on the buccal cusps o f the upper molars and like markings on the buccal groove o f the lower molars, the normal occlusal relation of the molars and normal rela tion o f the long axis o f the molars in respect to each other, and their relation to the denture as a whole, as well as their relation to the skull. In selecting the illustrations, typical models were taken from the several groups studied to show some of the con ditions described.
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Figure 2, Model 8, taken from the group with one molar missing, shows that the space which should be occupied by the upper left first molar has been reduced to about three quarters of its mesiodistal diameter. This has resulted because o f mesial drifting o f the upper second and third molars and the distal drifting of the teeth anterior, which has produced an end-to-end relation o f the upper lateral incisor with the lower cuspid, o f the upper cus pid with the lower first bicuspid, o f the
F ig . 2.— M o d e l tak en f ro m the g ro u p w ith one m o la r m issing.
upper first bicuspid with the lower second bicuspid and of the upper second bicuspid with the mesial cusp of the lower first molar. The crowded condition o f the an terior teeth has not been relieved by the extraction o f the upper left first molar, as the upper left cuspid as shown in Figure 2 is still in buccal occlusion, and the upper left lateral incisor still has its distal angle rotated to the lingual. Also, the lower anterior teeth remain in their original crowded condition, which, in all probability, will be aggravated by the future eruption o f a lower left third molar.
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Figure 3, Model 3, taken from the group with three molars missing, shows the effects o f the loss o f the lower first permanent molar. The lower second and third molars have tipped mesially as indicated by the india ink markings (compare Figure 1). By this tipping, both inclined planes o f the mesiobuccal cusp o f the lower first molar and the distal inclined plane o f the mesial cusp o f the upper first molar have lost all
Figure 4, Model 23, taken from the group with one lower molar missing, shows that, as a result of the loss o f the lower first molar, the second and third lower molars have drifted mesially, as indicated by the india ink markings, (compare Figure 1) only one full cusp. Also, the lower second bicuspid has drifted distally to contact with the lower second molar, with a serious change o f the long axis of the bicuspid. The lower first bicuspid has tipped
F ig . 3.— M o d e l ta k e n f ro m th e g ro u p w ith th ree m o lars m issin g.
F ig . 4.— M o d e l tak en f ro m th e g ro u p w ith one lo w e r m o la r m issing.
occlusal contact. The mesial inclined plane o f the mesiobuccal cusp of the upper first molar and the distal in clined plane of the buccal cusp o f the upper second bicuspid have lost all occlusal contact because o f the loss of the lower first molar. The correspond ing inclined planes o f the lingual cusps have also lost their occlusal contact. Figure 3 further illustrates the distal drifting of the lower bicuspids, which have drifted together, partially closing the space of the lost molar and opening a space between the lower right cuspid and the first bicuspid.
distally, the lower left cuspid likewise, producing an end-to-end relation with their opposing fellows. In addition to the inclined planes of the lower first molar lost by the extraction, the distal inclined plane o f the upper first bicus pid, the mesial inclined plane o f the mesial cusp of the upper second bicuspid, the distal inclined plane of the lower first bicuspid and the mesial inclined plane o f the lower second bicuspid are lost to occlusion. Figure 5, Model 5, a right view taken from the group with two lower molars missing, illustrates the effects of the extraction o f the lower first permanent
S iffy — Effects o f Loss o f First Perm anent M olar molar on the right side. The lower right second and third molars have tipped mesially, seriously changing the long axis o f these teeth. The two lower bicuspids have tipped distally, opening spaces between the second and the first bicuspid and between the first bicuspid and the lower right cuspid. Spaces are also seen between the lower anterior teeth. The lower second bi cuspid is also rotated one quarter on its axis. In the upper arch, the crown of the right second bicuspid is missing, but
F ig . 5.— M o d e l, r ig h t view , tak en f ro m th e g ro u p w ith tw o lo w e r m o lars m issing.
the root is present and has been prepared for a post crown. The presence of the root and the evidence o f recent dental work shows that this part o f the mutila tion is recent and has had no past in fluence in the malocclusion. The upper right first molar is decidedly in supra clusion, owing to the lack of occlusal resistance caused by the loss o f the lower right molar, the tipping mesially o f the lower second molar and the one quarter rotation o f the lower second bicuspid. The loss o f occlusal contact on the right side of this denture because o f the loss of the lower first molar is all of the lower second molars and the second
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bicuspids, as well as the extracted molar, all o f the upper molar and the mesial inclines o f the mesial cusp of the upper second molar. Figure 6, Model 5, left view, shows the result of the loss o f the lower left first molar. The lower second and third molars have tipped mesially, partly closing the space that should be occupied by the missing lower left first molar. The lower left cuspid and bicuspids have tipped distally, one full cusp producing a distal occlusion for these teeth, and the
F ig . 6.— M o d e l, le f t view , sh o w in g the re su lt o f the loss o f th e lo w e r l e f t first m o la r.
second bicuspid has rotated about one quarter on its axis. The upper left first molar has been mutilated by the poorly constructed gold shell crown, which is lacking in any effort toward restoring anatomic contour or occlusal surface. The loss o f occlusal contact to the left side o f this denture in addition to all of the missing lower first molar is of the distal half and all o f the lingual sur face of the upper left first molars, the mesial and distal inclined planes of the upper left second molar, the mesial in clined plane of the distal cusp, and the distal and mesial inclined planes of the
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mesiobuccal cusp o f the lower second molar. Figure 7, right view o f Model 6, taken from the group with four molars missing, shows the effect o f the loss of the lower right first molar. The lower right second and third molars have tipped mesially, partially closing the lower first molar space. The lower right bicuspids have drifted distally a little, and the lower right second bi cuspid has rotated about one quarter on
F ig . 7.— R ig h t v iew o f m o d el tak en f ro m th e g ro u p w ith f o u r m o la rs m issing.
its axis. Because of this rotation, the influence of the opposing inclined planes has caused the upper right second bi cuspid to rotate about one eighth on its axis. The loss o f occlusal contact to the right half of this denture is of the lower right first molar, which is the one miss ing, practically all o f the four right bicuspids, the mesial and distal inclines of the mesial cusps o f the upper right first and the lower right second molars. Figure 8, left view of Model 6, illus trates the effects o f the loss o f the lower left first molar. T he lower left second
and third molars have tipped and drifted mesially to contact with the lower left second bicuspid. By the change in the long axis o f the lower left second molar by tipping and because o f the deficiency in the normal proportion of the crown o f the upper left second bi cuspid, the loss in occlusal contact to this left side o f the denture besides the missing molar is the distal incline of the buccal cusp o f the lower left second
F ig . 8.— L e f t v ie w o f m o d el illu s tr a tin g the effects o f the loss o f the lo w e r le f t first m o la r.
bicuspid, the mesial incline o f the mesio buccal cusp o f the lower left second molar; also both inclines of the upper left second bicuspid, which is not due to the loss o f the molar, but does com plicate the occlusion in this instance. Figure 9, right view o f Model 12, taken from the group with three molars missing, illustrates the effect of the loss of the upper right first molar. The upper right second and third molars have tipped and drifted mesially. The teeth anterior to the missing molar have all drifted distally, closing the space of
Sifpy— Effects o f Loss o f First Perm anent M olar the missing molar and producing a mesial occlusion of the lower arch, a Class III malocclusion. The principal loss to occlusal relation is in the anterior teeth because o f lack o f normal over bite. Figure 10, left view o f Model 12, illustrates the effect o f the loss o f both left first permanent molars. The space o f the upper left first molar is closed by the tipping and drifting o f the upper left second molar and the distal drifting
F ig . 9.— R ig h t v iew o f m o d e l tak en f ro m th e g ro u p w ith th re e m o la rs m issing.
o f all teeth anterior to it. The space of the lower left first molar is likewise closed by the mesial drifting and tipping o f both the lower left second and third molars and the distal tipping of the lower left bicuspid. The change in long axis o f these teeth is indicated by india ink markings on the cast. The angle o f divergence is greater here than in the upper left teeth. The distal shifting o f the upper six anterior teeth and the four upper bicuspids (compare Figure 9) shows that the effects o f the extractions are bilateral and the result is a Class III malocclusion. It is im portant to note that the extraction o f
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the lower left first molar has not counteracted this influence. Figure 11, right view o f Model 1, taken from the group with two lower molars missing, illustrates the effect of the extraction o f the lower right first permanent molar. The lower right second and third molars have tipped and drifted mesially one full cusp. The lower right bicuspids and the anterior teeth have drifted lingually. This tipping and drifting o f all the remain ing lower teeth subsequent to the ex-
F ig . 10.— L e f t v iew o f m o d e l illu s tr a tin g th e effect o f th e loss o f b o th le f t first p e r m a n e n t m o lars.
traction o f the lower right first molar has closed its space. The extreme angle o f divergence o f the long axis o f the lower bicuspids and molars is again seen, as indicated by the india ink mark ings on the cast. Figure 12, left view o f Model 1, illustrates the effect o f the loss o f the lower left first permanent molar. The same reaction o f the molars, bicuspids and anterior teeth is shown here as is illustrated and described in Figure 11, the opposite side o f the denture. It is important to note that the shortening of the lower denture by the extraction of
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the two lower first molars has caused the upper anterior teeth to become very irregular because o f lack o f normal re sistance from the lower anterior teeth, which are quite regular. The upper left cuspid is entirely in buccal occlusion, the upper left lateral is in lingual occlusion, the distal angle of the upper left central is rotated to the lingual and the distal angle o f the upper right central is rotated to the
stances when some such practice may seem advisable. In a large proportion o f dentures, the loss o f one or more first molars, unless the spaces are promptly main tained by artificial substitutes, causes a shortening or narrowing or both nar rowing and shortening o f the denture, either by collapse o f the arches or a failure in their normal development, if the denture has not reached its complete
F ig . 11.— M o d e l, r ig h t view , taken f ro m th e g ro u p w ith tw o lo w e r m o la rs m issing.
F ig . 12.— L e f t v iew o f m o d el sh o w in g the effect o f th e loss o f the lo w e r le f t first p e r m a n e n t m o la r.
labial. The upper long axis of the upper and lower right cuspids are in the development. The malpositions of teeth same plane, which throws the upper are not corrected by the extraction of first molars, but, considering the den right cuspid in buccal occlusion. ture in its entirety, the malpositions o f teeth are increased. As a result o f this study, it is con The dentures represented in the 100 cluded that the loss of a first permanent models studied are those of persons molar is not an advantage to any den whose ages range from 18 to 30 years. ture. As a general principle, if one first In subjects so mature, it may be said molar is lost, it is not good practice to that the malocclusion had reached the extract the corresponding molar in the final stage o f development as long as same arch or to extract the remaining conditions were unchanged. However, first molars. There may be rare in occlusion or malocclusion at any age is C O N C L U S I O N S
S iffy — Effects o f Loss o f First Perm anent M olar
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susceptible to any abnormal force. The that the loss o f the first permanent loss o f tooth substance, if it is not molar from a denture having occlusion promptly and properly restored to nor induces malocclusion. mal anatomic proportions, injures any denture t o the extent to which the nor H. B . S in g le r, SfringjielcL , I II .: W e h ave mal relation of inclined planes is ju s t h e a rd the m o st scientific p a p e r ever w r it ten on th is su b je ct, in m y o p in io n . T h e re affected. rem ain s little f o r me to discuss. D r . S ippy Most o f the first molar spaces are has g iv en co n sid erab le tim e a n d e ffo rt to partly closed by the tipping, drifting c o llectin g these d a ta , w h ich the av e ra g e m an or tipping and drifting o f adjacent w o u ld be a lif e tim e in a c q u irin g . I m y se lf a m p le o f the m isch ief w hich m ay teeth. In a few cases, the first molar famo lloawn ex th e loss o f the f o u r first p erm an en t space is closed. This is usually ac m o lars, a n d I h av e precisely the tro u b le th a t complished by the tipping o f the second D r. S ippy has in d ic a te d . T h e e x tra c tio n , in w as due to caries, a n d n o t f o r the molar mesially and of the bicuspids and mcoyrrecase, ctio n o f m alo cclu sio n . In m y o pinion, anterior teeth distally. the first m o la rs e x tra c te d f o r the r e lie f o f a The change in the relation o f the cro w d ed c o n d itio n m ake u p a v ery sm a ll p e r b u t m a n y a re lo st as the resu lt long axis of the tipped teeth places an ocentage, f caries, m o stly d u r in g g ra d e school ag e. additional and abnormal strain on the D r. S e ife rt h a d occasion to ex am in e em ployes peridental membrane attached to those o f th e S an g am o M e te r W o rk s a n d o f th irty in ed , b etw een the ages o f 18 a n d 35, teeth. The open contacts in the anterior no inn lye extwam o h ad a ll th e first p e rm a n e n t m o lars. and bicuspid region o f the dental A ll the rest h a d lo st one o r m o re. G ra n tin g arches, caused by the distal movement the f a c t th a t m o st o f these first m o la rs a r e lost of these teeth resulting from the lost th ro u g h caries, th e tro u b le begins n ot neces a f te r th e e x tra c tio n , b u t d u rin g the support of the missing molar, likewise spaerily rio d o f decay, w h en , th r o u g h f e a r o f p ain , places additional strain on the peridental the m a s tic a tin g is done on one side only. membrane. Consequently, this tissue, N o w th e m o v em en ts of- th e teeth f o llo w in g being overtaxed, is more susceptible to th e e x tra c tio n m a y be d iv id ed in to tw o in w h ic h th e first p erm an en t trauma and to infection, and the pack mg roo lau prss: a none d incisors o n ly a re in occlusion, an d ing of food against the gum tissue in th e o th e r in w h ic h the second m o la r o r the spaces produced by shifting teeth bicuspids o r b o th are in occlusion. T h ese offers an increased opportunity for in m a y be su b d iv id e d a g a in , a c c o rd in g to the m b er o f m o la rs lo s t: ( l ) in re g a rd to the fection. The short life of such teeth is nmuovem ents o f th e teeth in r e la tio n to one a matter of clinical history. a n o th e r, w hen th e fo rc e o f occlusion is tak en The masticating efficiency of the up e n tire ly by th e firs t m o la r s ; ( 2 ) in re g a r d denture is decreased not only by the to the ch an g e in th e re la tio n sh ip o f the m a n absence o f the one, two, three or four dible a n d m a x illa , w hen the fo rc e is dis n e n t teeth w hich are molars but also by the tipping, drifting trib u te d o v er a nthed (p3e)rmwa hen the te m p o ro m a n and rotating o f other teeth, so that they ind ibocclusion, u la r jo in t a n d bones o f the fa c e ch an g e. are lost, partially or entirely, to occlusal T h is u su a lly occurs w hen the p a tie n t is y o u n g e r a n d the bones a re m o re susceptible contact. A ll dentures examined indicate that to a b n o rm a l influence, w h ich resu lts in the o f th e lo n g itu d in a l ax is o f the sk u ll the loss o f the first permanent molar adeflection n d the g e n e ra l tw is tin g o f the bones. T h e not only does not correct existing mal a r tic u la r su rfa c e o f th e te m p o ra l o f the n o n occlusion but also aggravates it, and fu n c tio n in g side is h ig h e r th a n on the o th er. D I S C U S S I O N
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T h e Journal o f the Am erican D ental Association
T h e a tro p h ie d c o n d itio n o f the condyles in th e te m p o ro m a n d ib u la r jo in ts is p ro b a b ly due to th e f u n c tio n in g o f m a stic a to ry m uscles in e le v a tin g an d d ep ressing th e m a n d ib le, th ereb y in te r f e r in g w ith th e sy m m etrical d ev elo p m en t o f a ll the tissues o f the fa c e an d sk u ll. D r. S ip p y has g iv e n us a d etailed descrip tio n o f th e resu lts o f th e d r if tin g an d tip p in g o f the a d ja c e n t teeth , a n d I h ave trie d to g iv e you a f e w o f th e o th e r resu lts th a t accom pany th e loss o f th e first p e rm a n e n t m o la r. So f a r th ere h as been v ery little w ritte n on this su b je ct, w h ic h especially concerns the o r th o dontists. E . E . G ra h a m , C h icago, 111.: D r . S ippy has g iv e n us som e so u n d w o rk in g ideas w h ich e v e ry d e n tist in the sta te m ig h t w ell a d o p t. I a m f r a n k to ack n o w le d g e m y su rp rise a t le a r n in g f ro m D r . S ip p y ’s re v ie w o f d en tal lite ra tu r e , i f I h av e p ro p e rly u n d ersto o d his sta te m e n t, th a t th ere are an eq u al n u m b e r f o r a n d a g a in st th e e x tra c tio n o f the first p e rm a n e n t m o la rs to r e g u la te m alo cclu sio n by re lie v in g the cro w d ed conditions o f the teeth in th e arches. I k n ew w e h ad a fe w m en w h o th o u g h t a n d p ro b ab ly still th in k it a d visab le to e x tra c t the r e m a in in g th ree first m o la rs i f one is n ecessarily lo st b u t I h ad no id ea th ey n u m b e re d so m an y . I t is m y firm b e lie f th a t it is p ra c tic a lly n e v e r in d icated . T h e slides w e h av e review ed w o u ld seem c o n v in c in g evidence th a t no case ev er a g a in is n o rm a l a f t e r th e re m o v a l o f an y one o f th e first p e rm a n e n t m o la rs, a n d the a b n o r m a lity o n ly increases in p ro p o rtio n to the n u m b e r rem o v ed . I h av e y e t to see a n o rm a l o cclusion w hen th e second p e rm a n e n t m o la r
h ad been coaxed in to the place o f th e first. T h e in clin ed p lan es o f the o p p o sin g teeth are certain to strik e a b n o rm a lly a n d p ro d u ce a tra u m a tic occlusion. W h en w e realize th ere a re m o re th a n 100 la te r a l su rfaces o f cusps, a p p ro x im a te ly f ifty to be in p ro p e r re la tio n to the f i f t y in the o p p o sin g a rc h , we m u st k n o w th a t n o rm a l occlusion o f th e teeth is a delicate a rra n g e m e n t an d easily d isa r ra n g e d . D r. S ippy has, in his illu stra tio n s, p o in ted o u t th e v ario u s positions the teeth tak e a f t e r the firs t m o la r is lost. H e stated th a t o u t o f 118 spaces p a r tly closed, fo rty -, f o u r h av e re su lte d f ro m the tip p in g o f a d ja c e n t teeth a n d th irty -th re e f ro m the tip p in g an d d r i f ti n g o f a d ja c e n t teeth , w h ich changes th e lo n g axis a n d pro d u ces p e rid e n ta l dis tu rb an ce. T h e loss o f an y one o f the p e r m a n e n t teeth a f t e r a tim e m ay in d ire c tly affect th e f ittin g o f these in clin ed p lan es to each o th e r. A one o n e-th o u san d th inch m ove o r ch an g e o f p o sitio n m ay cause q u ite a con cussion on the delicate in v e stin g m em brane. I t is n o t th e s lig h t im m ed iate h a rm done th a t is o f p a r tic u la r consequence, b u t the ill effects becom e a vicious circle, g o in g f ro m bad to w orse. D r. S ippy stated th a t the m odels stu d ied w ere o f p atien ts betw een the ages o f 18 a n d 30 years. In m ost o f these cases, the re a lly h a r m f u l effects have n o t yet been ex perienced by the p atients. T h e exist in g c o n d itio n f a v o rs an e a rly loss o f a ll the teeth , w h ich m ig h t h ave o th erw ise been saved in a h e a lth y c o n d itio n . As I am th o ro u g h ly in sy m p a th y w ith D r . S ippy’s a ttitu d e on this subject, w h a t I w o u ld ad d w o u ld o n ly be superfluous.
THE JOURNAL O F THE
American Dental Association V ol . 14
NOVEMBER, 1927
No. 11
Original Communications THE EFFECTS OF THE LOSS OF THE FIRST PERMANENT MOLAR* B y B U R N E O . S IP P Y , B .S ., D .D .S ., M .S ., Chicago, Illinois
a review o f the scientific literature INinarticles medical and dental journals, many are found treating either
directly or indirectly the problems in volving the first permanent molar in the development o f the human denture. At the present time, conflicting theories exist among orthodontists, den tists and physicians with reference to the scientific value o f the first permanent molar in its relation to occlusion and to the management of malocclusion. These theories have had their influence on the dental profession as exemplified in articles and discussions published. A summary o f the review o f the literature may be made by saying that the authors are about equally divided * R e ad b e fo re th e Illin o is S tate Society, P e o ria , 111., M a y 10, 1927.
D e n ta l
1953
in favor o f and against the extraction of the first permanent molars, with a smaller group who are more conserva tive, taking an intermediate position, namely, extraction irj some instances and not in others. Those in favor o f extraction claim that it relieves the crowded condition o f the teeth in the arches, the second molars moving forward to take the place of the first molars and the third molars taking the place of the second molars, and thus the denture is greatly improved; also that this procedure is much the easiest and quickest way to obtain the desired result. Those in favor o f preserving the first permanent molar whenever possible point out its importance in the develop ment of the face and jaws, and its
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T h e Journal o f the Am erican D ental Association
effects in producing and maintaining occlusion. The conservative group are not so ready to extract first permanent molars unless the molars are in a very bad con dition, or unless the shape o f the face seems to indicate that the extraction w ill not show its effect. Some of this group would, in arches having crowded teeth, extract the bicuspids rather than the first molar, to relieve the crowding and improve the denture. The advocates o f extraction either of the first molar or the bicuspid differ as to how far to carry the plan. Some would extract only one tooth; some ad vise the extraction o f the same tooth on both sides o f the arch; while others advise the removal o f all four corre sponding teeth, if any are to be lost, to relieve the crowded arches, on the premise that the least amount o f damage w ill be done to the denture by such a procedure. There is no trend o f interest either for or against the extraction o f the first molar in the literature from 1856 to the present time. Considering the liter ature chronologically, the proportion of arguments for and against is about equal. Most o f the statements in the articles and discussions reviewed have been made on the basis of experience in individual practice extending over a period o f years, without data or sys tematic study o f effects. Such opinions are not always logical or correct, nor are they clearly expressed. At least one exception is an article by Frederick B. Noyes (1 9 2 2 ) which includes photo graphs, orthodontia casts of the jaws and case histories of patients presented in the article. In order to determine which o f the before' mentioned groups are sound in their advice, I determined to make a
study o f the problem upon a scientific basis involving dentures which had had time to show the effects o f first molar loss, and thereby eliminate the “hear say” element. Orthodontia models were made from impressions o f mouths o f a group of about 400 individuals, from 18 to 30 years o f age. This collection was be gun at the orthodontia clinic o f the University o f Illinois, College of D en tistry, in 1918. The mouths represented by this group had received the ordinary dental care but no orthodontic manage ment. There are no case histories accompanying the models and no photo graphs or radiograms. Therefore, the models were studied all the more care fully and the selection and classification of a model was made only when it presented unquestionable conditions. This cut down the number o f models available very materially. One hun dred models which showed a loss of the first permanent molar were selected, and were classified in several ways in order to determine in what manner they could be studied best. The 100 models were finally grouped. The number falling in each group is shown in Table 1. T
able
G ro u p 4 3 2 1 2 1 2
1.— G r o u p in g
of
M
odels
S t u d ie d N o.
first m o la rs m is s in g _____________________ 6 first m o lars m issin g ______________________ 12 u p p e r first m o la rs m issing------------------------ 1 u p p e r first m o la r m issin g -------------------------- 10 lo w e r first m o la rs m issing-_______________ 31 lo w e r first m o la r m issin g ------------------------30 first m o lars m issing in opposite sides an d opposite arches __________________________ 10
The individual models of each group were then studied to determine the re lation of the loss of the first permanent
S iffy — Effects o f Loss o f First Permanent M olar molar to the occlusion. It is quite obvious that the time allowed for this paper w ill not permit of a detailed de scription o f the findings in each model or even in each group o f models. The manuscript and tables covering this part o f the research work covers twenty or more typewritten pages. A summary of the findings in all groups is presented in Table 2. T able N o. o f M o d e ls 80 6 14 29 15 18 38 68 32 64 36 15 85 118 23 43 21
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mesial occlusion and 14 per cent have distal occlusion. No study has been recorded as to the relationship of arch conformation to malocclusion in any series of dentures as far as I know. In this study it is found that 38 per cent have arches ap parently not affected in length and width; 29 per cent have narrow arches; 15 per cent have short arches, and 18
2.— S u m m a r y o f
A l l G roups*
C o n d itio n S how n
N o rm a l m esio d istal re la tio n o f the arches M e sial o cclusion o f the arches D ista l o cclusion o f th e arches N a r ro w arch es S h o rt arches N a r ro w a n d sh o rt arches L e n g th a n d w id th o f archcs a p p a re n tly n o t affected M a lp o sitio n o f teeth L ittle d istu rb an ce in m a stic a tin g efficiency F irs t p e rm a n e n t m o la rs m issing o n ly , e x c e p tin g th ird m o lars F irs t p e rm a n e n t m o la rs an d o th e r teeth m issing T w e n ty -o n e b rid g es N o a rtific ia l re sto ra tio n o f the m issing first p e rm a n e n t m o la rs Spaces p a r tly closed, 44 by tip p in g , 41 by d r if tin g , 33 b y tip p in g an d d r if t in g Spaces p a r tly closed, 6 by tip p in g , 8 by d r if tin g , 9 by tip p in g a n d d r if t in g Spaces m a in ta in e d by b rid g e w o rk o r occlusion Spaces d ev elo p ed betw een o th e r teeth in th e d e n tu re , a re su lt o f th e loss o f first p e rm a n e n t m o lars
*O ne h u n d re d m o d els re p re se n tin g 184 m issing first m o lars.
re c a p itu la tio n
o f fin d in g s
The proportion o f malocclusion belonging to each class o f malocclusion has been given as about 70 per cent having normal mesiodistal relation o f the arches, 4 per cent having mesial occlusion and 26 per cent having distal occlusion. In the study o f the 100 models, it is recorded in the summary of findings that the malocclusion follows about the same proportion: 80 per cent have normal mesiodistal relation o f the arches, 6 per cent have
per cent have short and narrow arches. Therefore, 62 per cent have been affected in length and width. This would seem to be a large percentage, a much larger percentage than would be expected in a group o f 100 models showing malocclusion. This high percentage o f undersized arches is due to the collapse o f the arches or failure o f normal development o f the arches because of the loss of the first permanent molars, It is found that 68 per cent o f the dentures show malposition o f teeth. A
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T h e Journal o f the Am erican D ental Association
large percentage o f this group have very serious malpositions o f teeth as none were recorded as such unless o f a serious nature. The percentage o f den tures showing little disturbance in mas ticating efficiency is 32. It is a natural conclusion that the percentage o f malposed teeth has not been reduced by the loss o f the first permanent molars, and the crowding o f teeth, so-called, has not been relieved. As there are no records available as to the proportion being considered, it is difficult to draw comparisons, but it would seem that the percentage o f dentures having serious malpositions is relatively high consider ing all classes o f malocclusion. O f the dentures studied, 64 per cent have lost one or more first permanent molars, excepting the third molars; 36 per cent o f these dentures have other teeth missing in addition to the first molars; 61 per cent have one or both lower first molars missing without the absence o f either upper first molar; 89 per cent have lost one or both lower first molars with the absence o f one or both upper first molars. Only 11 per cent o f the 100 dentures have lost one or both upper first molars without the loss of either lower first molar. The high percentage o f lower first molar extractions is significant. It is evident that the first molar is the one tooth in the denture which has been the prey of the extracting forceps, and particularly the lower first permanent molar. No artificial restorations o f the miss ing first molars by dental bridges was found in 85 per cent o f the dentures. Only 15 per cent o f the dentures have bridgework. This represents twentyone bridges o f a possible 184. This is a surprisingly low percentage o f restora tions, and it accounts for many o f the complications in the malocclusion of
most o f the dentures. In the forty-three first molar spaces maintained, only twenty-one bridges are a factor, the re maining twenty-two spaces being main tained by the normal influences of occlusion or because o f the fact that the extractions have been recent, sufficient time not having elapsed to determine whether or not the influences w ill con tinue to maintain these spaces. O f the 118 spaces partly closed, in forty-four this condition has resulted from the tipping of adjacent teeth, which changes the long axis of these teeth. T he partial closure of thirty-three spaces o f lost first molars has resulted from the tipping and drifting of adja cent teeth; therefore, 77 o f the 118 spaces have partly closed as a resultof the tipping o f adjacent teeth. A tremendous additional and abnormal strain is placed on the peridental membrane attached to these teeth, and as clinical evidence shows that this supporting tissue has its limits o f endurance to punishment, a large number of these teeth w ill be lost at an early age, in addition to the now missing first molars. The partial closure of forty-one spaces by bodily drifting in the bone o f adjacent teeth without changing of their long axis does not influence the peridental membrane par ticularly, but a normal dental bridge cannot be placed. An undersized bridge may be constructed that is neither effi cient nor satisfactory. Considering in the same manner the twenty-three spaces o f the missing first molar that are closed, it is found that six are closed by tipping o f adjacent teeth, eight by drifting and nine by tipping and drifting. Fifteen o f the twenty-three spaces, therefore, have been closed by the changing o f the long axis o f the adjacent teeth, and addi tional and abnormal occlusal strain has
Sifipy— Effects o f Loss o f First Perm anent M olar been placed on their peridental mem brane. As contacts have been established in this group, this strain is not so serious as in the previous group, and these teeth have the support o f their adjacent fel lows by contact. O f the dentures studied, 21 per cent show spaces between teeth an terior to the missing molars. This has occurred by the tipping and drifting distally o f the six anterior teeth and the bicuspids. (Figs. 3-5.)
F ig . 1.— O cclusion j n o r m a l re la tio n o f the in clin ed p lan es w h en th e ja w s a re closed.
Figure 1 shows the normal relation of the inclined planes o f the teeth when the jaws are closed; namely, occlusion. It also shows, by the india ink markings on the buccal cusps o f the upper molars and like markings on the buccal groove o f the lower molars, the normal occlusal relation of the molars and normal rela tion o f the long axis o f the molars in respect to each other, and their relation to the denture as a whole, as well as their relation to the skull. In selecting the illustrations, typical models were taken from the several groups studied to show some of the con ditions described.
1957
Figure 2, Model 8, taken from the group with one molar missing, shows that the space which should be occupied by the upper left first molar has been reduced to about three quarters of its mesiodistal diameter. This has resulted because o f mesial drifting o f the upper second and third molars and the distal drifting of the teeth anterior, which has produced an end-to-end relation o f the upper lateral incisor with the lower cuspid, o f the upper cus pid with the lower first bicuspid, o f the
F ig . 2.— M o d e l tak en f ro m the g ro u p w ith one m o la r m issing.
upper first bicuspid with the lower second bicuspid and of the upper second bicuspid with the mesial cusp of the lower first molar. The crowded condition o f the an terior teeth has not been relieved by the extraction o f the upper left first molar, as the upper left cuspid as shown in Figure 2 is still in buccal occlusion, and the upper left lateral incisor still has its distal angle rotated to the lingual. Also, the lower anterior teeth remain in their original crowded condition, which, in all probability, will be aggravated by the future eruption o f a lower left third molar.
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T h e Journal o f the Am erican D ental Association
Figure 3, Model 3, taken from the group with three molars missing, shows the effects o f the loss o f the lower first permanent molar. The lower second and third molars have tipped mesially as indicated by the india ink markings (compare Figure 1). By this tipping, both inclined planes o f the mesiobuccal cusp o f the lower first molar and the distal inclined plane o f the mesial cusp o f the upper first molar have lost all
Figure 4, Model 23, taken from the group with one lower molar missing, shows that, as a result of the loss o f the lower first molar, the second and third lower molars have drifted mesially, as indicated by the india ink markings, (compare Figure 1) only one full cusp. Also, the lower second bicuspid has drifted distally to contact with the lower second molar, with a serious change o f the long axis of the bicuspid. The lower first bicuspid has tipped
F ig . 3.— M o d e l ta k e n f ro m th e g ro u p w ith th ree m o lars m issin g.
F ig . 4.— M o d e l tak en f ro m th e g ro u p w ith one lo w e r m o la r m issing.
occlusal contact. The mesial inclined plane o f the mesiobuccal cusp of the upper first molar and the distal in clined plane of the buccal cusp o f the upper second bicuspid have lost all occlusal contact because o f the loss of the lower first molar. The correspond ing inclined planes o f the lingual cusps have also lost their occlusal contact. Figure 3 further illustrates the distal drifting of the lower bicuspids, which have drifted together, partially closing the space of the lost molar and opening a space between the lower right cuspid and the first bicuspid.
distally, the lower left cuspid likewise, producing an end-to-end relation with their opposing fellows. In addition to the inclined planes of the lower first molar lost by the extraction, the distal inclined plane o f the upper first bicus pid, the mesial inclined plane o f the mesial cusp of the upper second bicuspid, the distal inclined plane of the lower first bicuspid and the mesial inclined plane o f the lower second bicuspid are lost to occlusion. Figure 5, Model 5, a right view taken from the group with two lower molars missing, illustrates the effects of the extraction o f the lower first permanent
S iffy — Effects o f Loss o f First Perm anent M olar molar on the right side. The lower right second and third molars have tipped mesially, seriously changing the long axis o f these teeth. The two lower bicuspids have tipped distally, opening spaces between the second and the first bicuspid and between the first bicuspid and the lower right cuspid. Spaces are also seen between the lower anterior teeth. The lower second bi cuspid is also rotated one quarter on its axis. In the upper arch, the crown of the right second bicuspid is missing, but
F ig . 5.— M o d e l, r ig h t view , tak en f ro m th e g ro u p w ith tw o lo w e r m o lars m issing.
the root is present and has been prepared for a post crown. The presence of the root and the evidence o f recent dental work shows that this part o f the mutila tion is recent and has had no past in fluence in the malocclusion. The upper right first molar is decidedly in supra clusion, owing to the lack of occlusal resistance caused by the loss o f the lower right molar, the tipping mesially o f the lower second molar and the one quarter rotation o f the lower second bicuspid. The loss o f occlusal contact on the right side of this denture because o f the loss of the lower first molar is all of the lower second molars and the second
1959
bicuspids, as well as the extracted molar, all o f the upper molar and the mesial inclines o f the mesial cusp of the upper second molar. Figure 6, Model 5, left view, shows the result of the loss o f the lower left first molar. The lower second and third molars have tipped mesially, partly closing the space that should be occupied by the missing lower left first molar. The lower left cuspid and bicuspids have tipped distally, one full cusp producing a distal occlusion for these teeth, and the
F ig . 6.— M o d e l, le f t view , sh o w in g the re su lt o f the loss o f th e lo w e r l e f t first m o la r.
second bicuspid has rotated about one quarter on its axis. The upper left first molar has been mutilated by the poorly constructed gold shell crown, which is lacking in any effort toward restoring anatomic contour or occlusal surface. The loss o f occlusal contact to the left side o f this denture in addition to all of the missing lower first molar is of the distal half and all o f the lingual sur face of the upper left first molars, the mesial and distal inclined planes of the upper left second molar, the mesial in clined plane of the distal cusp, and the distal and mesial inclined planes of the
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T h e Journal o f the Am erican D ental Association
mesiobuccal cusp o f the lower second molar. Figure 7, right view o f Model 6, taken from the group with four molars missing, shows the effect o f the loss of the lower right first molar. The lower right second and third molars have tipped mesially, partially closing the lower first molar space. The lower right bicuspids have drifted distally a little, and the lower right second bi cuspid has rotated about one quarter on
F ig . 7.— R ig h t v iew o f m o d el tak en f ro m th e g ro u p w ith f o u r m o la rs m issing.
its axis. Because of this rotation, the influence of the opposing inclined planes has caused the upper right second bi cuspid to rotate about one eighth on its axis. The loss o f occlusal contact to the right half of this denture is of the lower right first molar, which is the one miss ing, practically all o f the four right bicuspids, the mesial and distal inclines of the mesial cusps o f the upper right first and the lower right second molars. Figure 8, left view of Model 6, illus trates the effects o f the loss o f the lower left first molar. T he lower left second
and third molars have tipped and drifted mesially to contact with the lower left second bicuspid. By the change in the long axis o f the lower left second molar by tipping and because o f the deficiency in the normal proportion of the crown o f the upper left second bi cuspid, the loss in occlusal contact to this left side o f the denture besides the missing molar is the distal incline of the buccal cusp o f the lower left second
F ig . 8.— L e f t v ie w o f m o d el illu s tr a tin g the effects o f the loss o f the lo w e r le f t first m o la r.
bicuspid, the mesial incline o f the mesio buccal cusp o f the lower left second molar; also both inclines of the upper left second bicuspid, which is not due to the loss o f the molar, but does com plicate the occlusion in this instance. Figure 9, right view o f Model 12, taken from the group with three molars missing, illustrates the effect of the loss of the upper right first molar. The upper right second and third molars have tipped and drifted mesially. The teeth anterior to the missing molar have all drifted distally, closing the space of
Sifpy— Effects o f Loss o f First Perm anent M olar the missing molar and producing a mesial occlusion of the lower arch, a Class III malocclusion. The principal loss to occlusal relation is in the anterior teeth because o f lack o f normal over bite. Figure 10, left view o f Model 12, illustrates the effect o f the loss o f both left first permanent molars. The space o f the upper left first molar is closed by the tipping and drifting o f the upper left second molar and the distal drifting
F ig . 9.— R ig h t v iew o f m o d e l tak en f ro m th e g ro u p w ith th re e m o la rs m issing.
o f all teeth anterior to it. The space of the lower left first molar is likewise closed by the mesial drifting and tipping o f both the lower left second and third molars and the distal tipping of the lower left bicuspid. The change in long axis o f these teeth is indicated by india ink markings on the cast. The angle o f divergence is greater here than in the upper left teeth. The distal shifting o f the upper six anterior teeth and the four upper bicuspids (compare Figure 9) shows that the effects o f the extractions are bilateral and the result is a Class III malocclusion. It is im portant to note that the extraction o f
1961
the lower left first molar has not counteracted this influence. Figure 11, right view o f Model 1, taken from the group with two lower molars missing, illustrates the effect of the extraction o f the lower right first permanent molar. The lower right second and third molars have tipped and drifted mesially one full cusp. The lower right bicuspids and the anterior teeth have drifted lingually. This tipping and drifting o f all the remain ing lower teeth subsequent to the ex-
F ig . 10.— L e f t v iew o f m o d e l illu s tr a tin g th e effect o f th e loss o f b o th le f t first p e r m a n e n t m o lars.
traction o f the lower right first molar has closed its space. The extreme angle o f divergence o f the long axis o f the lower bicuspids and molars is again seen, as indicated by the india ink mark ings on the cast. Figure 12, left view o f Model 1, illustrates the effect o f the loss o f the lower left first permanent molar. The same reaction o f the molars, bicuspids and anterior teeth is shown here as is illustrated and described in Figure 11, the opposite side o f the denture. It is important to note that the shortening of the lower denture by the extraction of
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T h e Journal o f the Am erican D ental Association
the two lower first molars has caused the upper anterior teeth to become very irregular because o f lack o f normal re sistance from the lower anterior teeth, which are quite regular. The upper left cuspid is entirely in buccal occlusion, the upper left lateral is in lingual occlusion, the distal angle of the upper left central is rotated to the lingual and the distal angle o f the upper right central is rotated to the
stances when some such practice may seem advisable. In a large proportion o f dentures, the loss o f one or more first molars, unless the spaces are promptly main tained by artificial substitutes, causes a shortening or narrowing or both nar rowing and shortening o f the denture, either by collapse o f the arches or a failure in their normal development, if the denture has not reached its complete
F ig . 11.— M o d e l, r ig h t view , taken f ro m th e g ro u p w ith tw o lo w e r m o la rs m issing.
F ig . 12.— L e f t v iew o f m o d el sh o w in g the effect o f th e loss o f the lo w e r le f t first p e r m a n e n t m o la r.
labial. The upper long axis of the upper and lower right cuspids are in the development. The malpositions of teeth same plane, which throws the upper are not corrected by the extraction of first molars, but, considering the den right cuspid in buccal occlusion. ture in its entirety, the malpositions o f teeth are increased. As a result o f this study, it is con The dentures represented in the 100 cluded that the loss of a first permanent models studied are those of persons molar is not an advantage to any den whose ages range from 18 to 30 years. ture. As a general principle, if one first In subjects so mature, it may be said molar is lost, it is not good practice to that the malocclusion had reached the extract the corresponding molar in the final stage o f development as long as same arch or to extract the remaining conditions were unchanged. However, first molars. There may be rare in occlusion or malocclusion at any age is C O N C L U S I O N S
S iffy — Effects o f Loss o f First Perm anent M olar
1963
susceptible to any abnormal force. The that the loss o f the first permanent loss o f tooth substance, if it is not molar from a denture having occlusion promptly and properly restored to nor induces malocclusion. mal anatomic proportions, injures any denture t o the extent to which the nor H. B . S in g le r, SfringjielcL , I II .: W e h ave mal relation of inclined planes is ju s t h e a rd the m o st scientific p a p e r ever w r it ten on th is su b je ct, in m y o p in io n . T h e re affected. rem ain s little f o r me to discuss. D r . S ippy Most o f the first molar spaces are has g iv en co n sid erab le tim e a n d e ffo rt to partly closed by the tipping, drifting c o llectin g these d a ta , w h ich the av e ra g e m an or tipping and drifting o f adjacent w o u ld be a lif e tim e in a c q u irin g . I m y se lf a m p le o f the m isch ief w hich m ay teeth. In a few cases, the first molar famo lloawn ex th e loss o f the f o u r first p erm an en t space is closed. This is usually ac m o lars, a n d I h av e precisely the tro u b le th a t complished by the tipping o f the second D r. S ippy has in d ic a te d . T h e e x tra c tio n , in w as due to caries, a n d n o t f o r the molar mesially and of the bicuspids and mcoyrrecase, ctio n o f m alo cclu sio n . In m y o pinion, anterior teeth distally. the first m o la rs e x tra c te d f o r the r e lie f o f a The change in the relation o f the cro w d ed c o n d itio n m ake u p a v ery sm a ll p e r b u t m a n y a re lo st as the resu lt long axis of the tipped teeth places an ocentage, f caries, m o stly d u r in g g ra d e school ag e. additional and abnormal strain on the D r. S e ife rt h a d occasion to ex am in e em ployes peridental membrane attached to those o f th e S an g am o M e te r W o rk s a n d o f th irty in ed , b etw een the ages o f 18 a n d 35, teeth. The open contacts in the anterior no inn lye extwam o h ad a ll th e first p e rm a n e n t m o lars. and bicuspid region o f the dental A ll the rest h a d lo st one o r m o re. G ra n tin g arches, caused by the distal movement the f a c t th a t m o st o f these first m o la rs a r e lost of these teeth resulting from the lost th ro u g h caries, th e tro u b le begins n ot neces a f te r th e e x tra c tio n , b u t d u rin g the support of the missing molar, likewise spaerily rio d o f decay, w h en , th r o u g h f e a r o f p ain , places additional strain on the peridental the m a s tic a tin g is done on one side only. membrane. Consequently, this tissue, N o w th e m o v em en ts of- th e teeth f o llo w in g being overtaxed, is more susceptible to th e e x tra c tio n m a y be d iv id ed in to tw o in w h ic h th e first p erm an en t trauma and to infection, and the pack mg roo lau prss: a none d incisors o n ly a re in occlusion, an d ing of food against the gum tissue in th e o th e r in w h ic h the second m o la r o r the spaces produced by shifting teeth bicuspids o r b o th are in occlusion. T h ese offers an increased opportunity for in m a y be su b d iv id e d a g a in , a c c o rd in g to the m b er o f m o la rs lo s t: ( l ) in re g a rd to the fection. The short life of such teeth is nmuovem ents o f th e teeth in r e la tio n to one a matter of clinical history. a n o th e r, w hen th e fo rc e o f occlusion is tak en The masticating efficiency of the up e n tire ly by th e firs t m o la r s ; ( 2 ) in re g a r d denture is decreased not only by the to the ch an g e in th e re la tio n sh ip o f the m a n absence o f the one, two, three or four dible a n d m a x illa , w hen the fo rc e is dis n e n t teeth w hich are molars but also by the tipping, drifting trib u te d o v er a nthed (p3e)rmwa hen the te m p o ro m a n and rotating o f other teeth, so that they ind ibocclusion, u la r jo in t a n d bones o f the fa c e ch an g e. are lost, partially or entirely, to occlusal T h is u su a lly occurs w hen the p a tie n t is y o u n g e r a n d the bones a re m o re susceptible contact. A ll dentures examined indicate that to a b n o rm a l influence, w h ich resu lts in the o f th e lo n g itu d in a l ax is o f the sk u ll the loss o f the first permanent molar adeflection n d the g e n e ra l tw is tin g o f the bones. T h e not only does not correct existing mal a r tic u la r su rfa c e o f th e te m p o ra l o f the n o n occlusion but also aggravates it, and fu n c tio n in g side is h ig h e r th a n on the o th er. D I S C U S S I O N
1964
T h e Journal o f the Am erican D ental Association
T h e a tro p h ie d c o n d itio n o f the condyles in th e te m p o ro m a n d ib u la r jo in ts is p ro b a b ly due to th e f u n c tio n in g o f m a stic a to ry m uscles in e le v a tin g an d d ep ressing th e m a n d ib le, th ereb y in te r f e r in g w ith th e sy m m etrical d ev elo p m en t o f a ll the tissues o f the fa c e an d sk u ll. D r. S ip p y has g iv e n us a d etailed descrip tio n o f th e resu lts o f th e d r if tin g an d tip p in g o f the a d ja c e n t teeth , a n d I h ave trie d to g iv e you a f e w o f th e o th e r resu lts th a t accom pany th e loss o f th e first p e rm a n e n t m o la r. So f a r th ere h as been v ery little w ritte n on this su b je ct, w h ic h especially concerns the o r th o dontists. E . E . G ra h a m , C h icago, 111.: D r . S ippy has g iv e n us som e so u n d w o rk in g ideas w h ich e v e ry d e n tist in the sta te m ig h t w ell a d o p t. I a m f r a n k to ack n o w le d g e m y su rp rise a t le a r n in g f ro m D r . S ip p y ’s re v ie w o f d en tal lite ra tu r e , i f I h av e p ro p e rly u n d ersto o d his sta te m e n t, th a t th ere are an eq u al n u m b e r f o r a n d a g a in st th e e x tra c tio n o f the first p e rm a n e n t m o la rs to r e g u la te m alo cclu sio n by re lie v in g the cro w d ed conditions o f the teeth in th e arches. I k n ew w e h ad a fe w m en w h o th o u g h t a n d p ro b ab ly still th in k it a d visab le to e x tra c t the r e m a in in g th ree first m o la rs i f one is n ecessarily lo st b u t I h ad no id ea th ey n u m b e re d so m an y . I t is m y firm b e lie f th a t it is p ra c tic a lly n e v e r in d icated . T h e slides w e h av e review ed w o u ld seem c o n v in c in g evidence th a t no case ev er a g a in is n o rm a l a f t e r th e re m o v a l o f an y one o f th e first p e rm a n e n t m o la rs, a n d the a b n o r m a lity o n ly increases in p ro p o rtio n to the n u m b e r rem o v ed . I h av e y e t to see a n o rm a l o cclusion w hen th e second p e rm a n e n t m o la r
h ad been coaxed in to the place o f th e first. T h e in clin ed p lan es o f the o p p o sin g teeth are certain to strik e a b n o rm a lly a n d p ro d u ce a tra u m a tic occlusion. W h en w e realize th ere a re m o re th a n 100 la te r a l su rfaces o f cusps, a p p ro x im a te ly f ifty to be in p ro p e r re la tio n to the f i f t y in the o p p o sin g a rc h , we m u st k n o w th a t n o rm a l occlusion o f th e teeth is a delicate a rra n g e m e n t an d easily d isa r ra n g e d . D r. S ippy has, in his illu stra tio n s, p o in ted o u t th e v ario u s positions the teeth tak e a f t e r the firs t m o la r is lost. H e stated th a t o u t o f 118 spaces p a r tly closed, fo rty -, f o u r h av e re su lte d f ro m the tip p in g o f a d ja c e n t teeth a n d th irty -th re e f ro m the tip p in g an d d r i f ti n g o f a d ja c e n t teeth , w h ich changes th e lo n g axis a n d pro d u ces p e rid e n ta l dis tu rb an ce. T h e loss o f an y one o f the p e r m a n e n t teeth a f t e r a tim e m ay in d ire c tly affect th e f ittin g o f these in clin ed p lan es to each o th e r. A one o n e-th o u san d th inch m ove o r ch an g e o f p o sitio n m ay cause q u ite a con cussion on the delicate in v e stin g m em brane. I t is n o t th e s lig h t im m ed iate h a rm done th a t is o f p a r tic u la r consequence, b u t the ill effects becom e a vicious circle, g o in g f ro m bad to w orse. D r. S ippy stated th a t the m odels stu d ied w ere o f p atien ts betw een the ages o f 18 a n d 30 years. In m ost o f these cases, the re a lly h a r m f u l effects have n o t yet been ex perienced by the p atients. T h e exist in g c o n d itio n f a v o rs an e a rly loss o f a ll the teeth , w h ich m ig h t h ave o th erw ise been saved in a h e a lth y c o n d itio n . As I am th o ro u g h ly in sy m p a th y w ith D r . S ippy’s a ttitu d e on this subject, w h a t I w o u ld ad d w o u ld o n ly be superfluous.