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The “Key Ridge” As a Diagnostic Aid in Orthodontics
THE “KEY RIDGE” AS A DIAGNOSTIC AID IN ORTHODONTICS By M . A lden W
e in g a r t ,
INTRODUCTION
IN G E no one p e rfe ct m ethod o f diagnosis has been or is likely to be d eveloped, it is difficult to discuss the value o f the “ k ey ridge” as a d iag nostic aid w ith ou t incorporating a dis cussion o f diagnosis in general. D u rin g the past fifteen years, ortho dontic concepts and practice have u nder gone such a drastic renaissance as to leave the conscientious p ractitioner b e wildered. M ech a n ica l principles have been ju d iciou sly applied in the treatm ent o f m alocclusion. Satisfactory results have been obtained w ith various technical plans and adjustm ents, from the sim ple labial alinem ent w ire to the lingu al arch w ith au xiliary springs and the m ore in tricate assemblages requ iring the b an d in g o f all the teeth w ith various types of attachments. H ow ever, w e h ave freq u en tly been confronted w ith the realization th at id en tical technics and adjustm ents do not produce com parable results in apparen tly sim ilar types o f cases. T h e result has often been the discarding o f a rational techn ical procedure and adoption o f an other type. I t is obvious, therefore, that the fa u lt has been w ith m ethods o f classification and diagnosis, w h ich h a ve been chaotic and are based upon em piricism and fa l lacious theories. F or years, w e h a v e depended on A n g le’s classification as a basis fo r diag-
S
Read at the Fifth Annual Orthodontic Con ference, under the auspices of the Graduate Division o f the College of Dentistry, Univer sity of Southern California, August 5, 1941. Jour. A .D .A., Vol. 29, September 1, 1942
D .D .S ., N ew Y o rk , N . Y .
nosis. H ow ever, in the light o f present know ledge, this sim ple classification did n ot afford sufficient scope of application upon w h ich to d evelop an ad equ ate d iag nosis o f inherent m alocclusion as related to surrounding structures. Sim on brought our attention to the fa ct th a t a diagnosis based solely upon clin ical observation o f occlusal relation ships is totally inadequate. H e presented a technic w hich, w hile h avin g some
Fig. 1.— Basic concept of gnathostatic den ture reproduction.
weaknesses, a t least m ade us realize that a definite procedure m ust be adopted to orient the jaw s and teeth to the rest o f the head. R esearch b y B roadbent, T o d d and B rodie developed the valu e o f the cephalom etric roentgenogram and fu r ther convinced the m ore th o u gh tfu l stu dent o f orthodontics th a t the diagnostic technic m ust be elevated to a m ore scien tific basis. A n d n ow Atkinson supplies the m issing link in this diagnostic chain w ith the “ k ey rid ge,” a valu ab le landm ark w h ich serves to supplem ent all the other d ata as a fu rth er check for accu racy. I t m ust be borne in m ind, how ever, th at no one m ethod o f diagnosis can be considered infallible or invulnerable, and I 5®3
i584
T h e J o u r n a l o f t h e A m e r ic à n D e n t a l A s s o c ia t io n
th at since hum an ju d gm en t m ust be called upon to interpret our cases, w e must take ad van tage o f every know n aid and em p loy every m eans th a t w ill assist us in these interpretations. A fte r m any
g n a t h o s t a t ic
r e l a t io n
of
d e n t u r e to
CRANIOFACIAL HARMONY
In order to orient the denture in its relation to skull anatom y, a reproduction m ust b e related to three planes o f the
’NORMAL*
MANDIBULAR
RETRACTION
VERTICAL
HORIZONTAL
ATTRACTION
ABSTRACTION
F ig . 2.— D e v ia tio n s fro m “ n o rm a l” c r a n io fa c ia l re la tio n s.
years o f experim entation and experience, I am convinced th at a techn ic em ploying gnathostatic, photostatic and roentgenostatic d ata as herein described represents the best availab le p ractical means tow ard diagnostic accu racy in orthodontics.
head. T h ese three planes, w h ich give us aspects o f height, w id th and length, stand at right angles to each other and a r e : i. T h e F ra n k fo rt horizontal plane, w h ich passes through the eye points (orbitalia) and the ear points (trag ia).
W e i n g a r t — “ K e y R i d g e ” a s D i a g n o s t i c A id
Fig. 3.— G nath ostatic denture reproductions properly scribed for diagnostic interpretation.
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th e eye points and stands perpen dicular to the eye-ear plane. T h e cephalom etric landm arks used are the orbitalia, tragia and left gonion. T h e orbital (eye) point is located on the low er bony m argin o f the orbit d i rectly below the pupil o f the eye. T h e tragion (ear) point is the notch just above the tragus of the ear. T h e gonial point is the point behind and below the angle o f the jaw . A study o f F igu re 1 w ill help to visu al ize these cran iofacial landm arks. In the righ t illustration, it w ill be noted that the fa ce is divided into three equal p a r ts ; th a t the corner o f the m ou th (chelion) and the gnathion lie in the orbital plane, and that the anterior curve o f the chin is usu ally fou n d to lie in fron t o f the orbital plane. A vertical line draw n from the nasion parallel to the orbital plane w ill m ark the point o f the upper lip. T h e illustration on the left indicates the gnathostatic relation o f the denture, and it w ill be noted that, in the “ ideal norm ,” the orbital plane bisects the canine tooth. A n y m arked departure from these rela tionships is an indication that some
F ig. 4.— D en ture reproduction in w h ich gn athostatic m odels reveal m arked asym m etrical developm ent. T h is serious anom aly does not show in the u nrelated models.
2. T h e m ed ian sagittal plane, w hich divides the h ead into tw o equal parts. It passes through the raphe palati and is perpen dicular to the eye-ear plane. 3. T h e orbital plane, w hich intersects
m orphologic deviation exists, the nature of w h ich m ust be determ ined and anal yzed. F igu re 2 gra p h ically illustrates the several deviations that m ay be observed
i586
T h e J o u r n a l o f t h e A m e r ic a n D e n t a l A s s o c ia t io n
(d) In clin ation o f tooth axis. 2. From the orbital p la n e : (a) Sagittal sym m etry. GNATHOSTATIC DENTURE REPRODUCTIONS (b) A n teroposterior relationship. (c) In clin atio n o f tooth axis. In the gnathostatic casts, w e h a ve a 3. F ro m the eye-ear p la n e : reprod uction o f the denture th a t is an a (a) V e rtica l dim ension. tom ic in its en tirety to the three planes (b) F orm and an gle o f occlusal curve. m e n tio n e d : i. T h e upp er base is id en tical w ith (c) In clin atio n o f tooth axis. W ith the old-fashioned conventional the eye-ear plane o f the patien t. T h e m odels, w hich are m erely reproductions low er base is parallel to the upper. in the photostatic and roentgenostatic pictures.
HAWLEY
1
L C
GONIAL ANGLE M
P
SAQITTAl. PALATAL CURVE
TRANSVERSE PALATAL CURVE
TRANSVERSE PALATAL CURVE
SAOITTAL PALATAL CURVE
E - E -P
OCCLUSAL CURVE
OCCLUSAL CURVE
F ig . 5 .— G r a p h c h a rts s h o w in g n o rm p a tte r n s fo r 6, 12 a n d 18 years.
2. T h e anterior angles o f the bases coincide w ith the m edian plane. 3. T h e rig h t and left angles cor respond to the orbital plane. W ith the casts oriented in this m anner, a diagnostic stud y in relation to th e three planes w ill reveal the follow in g aspects : 1. F ro m the m edian plane : (a) T ran sverse sym m etry. (b ) A rch form . (c) P roportion o f w idth.
of teeth w ith ou t a n y relationship to skull structure, not on ly are these aspects obliterated, b u t also, in m an y cases, false representations o f existing conditions are visualized, w h ich doubtless prove m is lead in g in m an y cases. In F igu re 4, it w ill be noted th at the true an om aly o f a m arked asym m etrical developm ent was lost in the conventional m odel. T h e technic o f parallelin g the occlusal plane w ith the base presents a
W e in g a r t — “ K e y R id g e ” a s D i a g n o s t ic A id
condition that is rarely found in N ature. A s a m atter o f fa ct, the degree o f a n g u larity betw een the occlusal curve and the F ran kfo rt horizontal plane is abou t 11 fo r the right side and 13 for the left side and is rarely the same on the tw o sides. T h e diagnostic valu e o f the gnathostatic m odels increases im m easurably w hen th ey are properly scribed w ith the aid of the W aldron sym m etrograph and curve diagram s or graphs are prepared. T h ese curves are superim posed over in dicated norm patterns, w h ich serve as a diagnostic gu ide sim ilar to norm averages of w eight, height, etc. T h ree norm p a t terns are u s e d : 6, 12 and 18 years. T h is procedure is o f great value in
i 5 87
patient and th ey w ere cum bersom e for filing purposes. In the photostat, w hich is a p h oto graph w ith the head positioned in the horizontal plane, w e incorporate a c cu racy o f detail w ith sim plicity o f rep ro duction and obtain a fa cia l record w h ich is o f im m ense diagnostic value. In Figure 6, w e h ave a facial rep ro duction w hich supplem ents and is in h a r m ony w ith, the orientation o f the d en ture reproduction. W hen lines are draw n betw een the various cephalom etric points heretofore m entioned, such a photostat is m ost h elp fu l in analyzing and studying the features as they m ay va ry from the average norm .
Fig. 6.— Photostatic facial reproductions w ith diagnostic planes indicated.
com piling statistical d ata and, w hen sim ilarly recharted upon the com pletion o f treatm ent, offers conclusive evidence o f the actual changes that have been achieved. TH E PH O TO STA TIC RECORD
F rom the earliest days of orthodontics, photographs w ere used to record fa cia l disharm ony. T h a t these unrelated ph oto graphs w ere o f little diagnostic va lu e is evidenced b y the fa ct that they w ere dis carded in favor o f plaster masks. T h e ir construction was too arduous for the
A fixed focal distance, either onefourth or on e-half life-size, must be established and m aintained as a definite factor in the technic. W h en this is done, successive photostats o f patients taken du rin g treatm ent w ill h ave definite com p arative valu e in studying grow th changes resulting from treatm ent, p ar ticu larly o f the low er part o f the face, the so-called “ changeable area.” T H E ROENTGENOGRAPHIC RECORD
W e now have reproductions o f the denture and o f the fa ce w hich are re
i5 88
T h e J o u r n a l o f t h e A m e r ic a n D e n t a l A s s o c ia t io n
lated. A fu rth er record o f d en tofacial relations is obtained through the use o f cephalom etric roentgenogram s of the h ead w h ich show the orientation of the denture to the other fa cia l osseous stru c tures. H ere again, the various anatom ic landm arks are noted. It is now possible to take exact m easurem ents from the various planes d irectly on the bone and thus overcom e the weakness o f taking m easurements through the coverin g of soft tissues of unknow n thicknesses. In this m anner, the roentgenogram not only becomes a most valu able diagnostic aid, but, w hen taken serially, is also o f inesti-
tine procedure, needs no fu rth er com m ent. A w ell-rounded diagnostic study should also include a roentgenogram of the hand o f the developin g child. Th is w ill afford a study of the epiphysis, the ossification centers, the degree o f m in-
Fig. 8.— R oentgenogram of hand ; used for studying skeletal m aturation index.
Fig. 7.— Profile roentgenogram showing cephalom etric landm arks used to orient den ture to facial osseous structures.
m able value in studying and recording d en tofacial developm ental changes and checking the results o f orthodontic treat ment. Since the orthodontist is prim arily concerned w ith grow th and developm ent, d urin g w hich period the eruption o f teeth plays an im portant p art, the necessity fo r an x -ray series o f the ind ivid u al teeth, to gether w ith lateral ja w views, as a rou
Fig. 9.— M ax illa ry roentgenogram orients denture to “ key rid ge.”
w hich
eralization, etc. T hese roentgenogram s are checked w ith the h a n d standards of T o d d for norm al skeletal m aturation. T o com plete the diagnostic study, it
W e i n g a r t — “ K e y R i d g e ” a s D i a g n o s t i c A id
is essential to predeterm ine the exact positioning o f the ind ivid u al teeth in the skull. It rem ained fo r A tkin son to give us this missing link in the diagnostic chain, the “ key rid ge,” th at strong buttress o f bone w hich descends and goes forw ard from the zygom a to the m axillary bone and acts as a support for the m axillary first m olar. In the adult, the ridge lies d irectly over the mesiobuccal root o f the m axillary first m olar. A m a xillary roentgenogram presents an excellen t orientation o f the denture to the “ k ey ridge.” T h is view affords not on ly a detailed study o f the correct posi tioning o f the teeth in the skull, bu t also an excellen t study of arch form as re lated to the surrounding b on y structures. In m an y instances, the posterior palatine suture is also visible, w hich offers an a d ditional check fo r accuracy. d if f e r e n t ia l d ia g n o s is
W ith the foregoing gnathostatic, photostatic and roentgenostatic d ata at hand, a differential diagnosis o f the den ture, accord in g to the three planes as established, is p r e p a r e d : A . R elation o f the lateral halves to the m edian plane. 1. C on traction (T o o near to the m edian p la n e ). 2. D istraction (T o o fa r from the m edian p la n e ). B. R elation to the orbital plane. 1. Protraction (anterior to n orm al). 2. R etraction (posterior to n orm al). C . R elation to the horizontal plane. 1. A ttra ctio n (too close to the eye-ear p la n e). 2. A bstraction (too distant from the eye-ear p la n e ). D eviations are furth er classified as in cisal, lateral and total, in horizontal localization. V e rtica l localization is designated as dental, alveolar, m axillary and m andibular. Since it m ust be conceded that the denture is not an isolated b od y, b u t an anatom ic and physiologic part o f the
I589
head, it is not the intention o f this pres entation to elaborate fu rth er on the rela tive valu e o f a diagnostic procedure based upon cephalom etric investigations. C o n tra ry to m an y opinions, the p re paratory technic is not an arduous one. W ith a little experience, the takin g o f the impressions w ill consum e no m ore tim e than a n y other satisfactory im pres sion technic. T h e laboratory procedure, in fa ct, takes even less tim e than the trim m ing o f conventional m odels to artistic p rop ortion s; w h ile the prep ara tion o f the graphs can be delegated to an efficient assistant. Regardless o f the tim e elem ent in volved, an appreciation o f the valu e o f a gnathostatic technic as the basis o f a routine diagnostic procedure can be had only if one w ill ad opt its principles in practice. W e are indebted to R a lp h W aldron fo r his research and experim entation in this field. O n his original technic, these procedures are based. BIBLIO G R A PH Y
1. S i m o n , P. W .: Fundamental Principles of Systematic Diagnosis of Dental Anomalies. (Translated by B. E. Lischer.) Boston: The Stratford Co., 1926. 2. B r o a d b e n t , B. H .: New X -R ay T ech nique and Its Application to Orthodontia. Angle Orthodontist, 1:45, No. 1, 1931. 3. Idem : Bolton Standards and Technique in Orthodontic Practice. Angle Orthodontist, 7:209, No. 4, 1937. 4.. H i g l e y , L. B .: Head Positioner for Sci entific Radiographic and Photographic Pur poses. Internat. J. Orthodontia, 22:699, July
1936. 5 . L o w y , R ic h a r d : Diagnosis. Am. J. Orthodontics, 24:762, August 1938. 6. T o d d , T . W .: Record of Metabolism Im printed on Skeleton. Am. J. Orthodontics, 2 4 :8 n , September 1938. 7. Idem: Atlas of Skeletal Maturation. Part. 1. Hand. St. Louis: C . V . Mosby Co., 1937 8. M c C o y , J. D .: Applied Orthodontics. Ed. 4. Philadelphia: Lea & Febiger, 1935. 9. A t k i n s o n , S. R .: Strategy of O rtho dontic Treatment. J.A .D .A ., 24:560, April 1937119 West Fifty-Seventh Street.
e in g a r t ,
INTRODUCTION
IN G E no one p e rfe ct m ethod o f diagnosis has been or is likely to be d eveloped, it is difficult to discuss the value o f the “ k ey ridge” as a d iag nostic aid w ith ou t incorporating a dis cussion o f diagnosis in general. D u rin g the past fifteen years, ortho dontic concepts and practice have u nder gone such a drastic renaissance as to leave the conscientious p ractitioner b e wildered. M ech a n ica l principles have been ju d iciou sly applied in the treatm ent o f m alocclusion. Satisfactory results have been obtained w ith various technical plans and adjustm ents, from the sim ple labial alinem ent w ire to the lingu al arch w ith au xiliary springs and the m ore in tricate assemblages requ iring the b an d in g o f all the teeth w ith various types of attachments. H ow ever, w e h ave freq u en tly been confronted w ith the realization th at id en tical technics and adjustm ents do not produce com parable results in apparen tly sim ilar types o f cases. T h e result has often been the discarding o f a rational techn ical procedure and adoption o f an other type. I t is obvious, therefore, that the fa u lt has been w ith m ethods o f classification and diagnosis, w h ich h a ve been chaotic and are based upon em piricism and fa l lacious theories. F or years, w e h a v e depended on A n g le’s classification as a basis fo r diag-
S
Read at the Fifth Annual Orthodontic Con ference, under the auspices of the Graduate Division o f the College of Dentistry, Univer sity of Southern California, August 5, 1941. Jour. A .D .A., Vol. 29, September 1, 1942
D .D .S ., N ew Y o rk , N . Y .
nosis. H ow ever, in the light o f present know ledge, this sim ple classification did n ot afford sufficient scope of application upon w h ich to d evelop an ad equ ate d iag nosis o f inherent m alocclusion as related to surrounding structures. Sim on brought our attention to the fa ct th a t a diagnosis based solely upon clin ical observation o f occlusal relation ships is totally inadequate. H e presented a technic w hich, w hile h avin g some
Fig. 1.— Basic concept of gnathostatic den ture reproduction.
weaknesses, a t least m ade us realize that a definite procedure m ust be adopted to orient the jaw s and teeth to the rest o f the head. R esearch b y B roadbent, T o d d and B rodie developed the valu e o f the cephalom etric roentgenogram and fu r ther convinced the m ore th o u gh tfu l stu dent o f orthodontics th a t the diagnostic technic m ust be elevated to a m ore scien tific basis. A n d n ow Atkinson supplies the m issing link in this diagnostic chain w ith the “ k ey rid ge,” a valu ab le landm ark w h ich serves to supplem ent all the other d ata as a fu rth er check for accu racy. I t m ust be borne in m ind, how ever, th at no one m ethod o f diagnosis can be considered infallible or invulnerable, and I 5®3
i584
T h e J o u r n a l o f t h e A m e r ic à n D e n t a l A s s o c ia t io n
th at since hum an ju d gm en t m ust be called upon to interpret our cases, w e must take ad van tage o f every know n aid and em p loy every m eans th a t w ill assist us in these interpretations. A fte r m any
g n a t h o s t a t ic
r e l a t io n
of
d e n t u r e to
CRANIOFACIAL HARMONY
In order to orient the denture in its relation to skull anatom y, a reproduction m ust b e related to three planes o f the
’NORMAL*
MANDIBULAR
RETRACTION
VERTICAL
HORIZONTAL
ATTRACTION
ABSTRACTION
F ig . 2.— D e v ia tio n s fro m “ n o rm a l” c r a n io fa c ia l re la tio n s.
years o f experim entation and experience, I am convinced th at a techn ic em ploying gnathostatic, photostatic and roentgenostatic d ata as herein described represents the best availab le p ractical means tow ard diagnostic accu racy in orthodontics.
head. T h ese three planes, w h ich give us aspects o f height, w id th and length, stand at right angles to each other and a r e : i. T h e F ra n k fo rt horizontal plane, w h ich passes through the eye points (orbitalia) and the ear points (trag ia).
W e i n g a r t — “ K e y R i d g e ” a s D i a g n o s t i c A id
Fig. 3.— G nath ostatic denture reproductions properly scribed for diagnostic interpretation.
i5 85
th e eye points and stands perpen dicular to the eye-ear plane. T h e cephalom etric landm arks used are the orbitalia, tragia and left gonion. T h e orbital (eye) point is located on the low er bony m argin o f the orbit d i rectly below the pupil o f the eye. T h e tragion (ear) point is the notch just above the tragus of the ear. T h e gonial point is the point behind and below the angle o f the jaw . A study o f F igu re 1 w ill help to visu al ize these cran iofacial landm arks. In the righ t illustration, it w ill be noted that the fa ce is divided into three equal p a r ts ; th a t the corner o f the m ou th (chelion) and the gnathion lie in the orbital plane, and that the anterior curve o f the chin is usu ally fou n d to lie in fron t o f the orbital plane. A vertical line draw n from the nasion parallel to the orbital plane w ill m ark the point o f the upper lip. T h e illustration on the left indicates the gnathostatic relation o f the denture, and it w ill be noted that, in the “ ideal norm ,” the orbital plane bisects the canine tooth. A n y m arked departure from these rela tionships is an indication that some
F ig. 4.— D en ture reproduction in w h ich gn athostatic m odels reveal m arked asym m etrical developm ent. T h is serious anom aly does not show in the u nrelated models.
2. T h e m ed ian sagittal plane, w hich divides the h ead into tw o equal parts. It passes through the raphe palati and is perpen dicular to the eye-ear plane. 3. T h e orbital plane, w hich intersects
m orphologic deviation exists, the nature of w h ich m ust be determ ined and anal yzed. F igu re 2 gra p h ically illustrates the several deviations that m ay be observed
i586
T h e J o u r n a l o f t h e A m e r ic a n D e n t a l A s s o c ia t io n
(d) In clin ation o f tooth axis. 2. From the orbital p la n e : (a) Sagittal sym m etry. GNATHOSTATIC DENTURE REPRODUCTIONS (b) A n teroposterior relationship. (c) In clin atio n o f tooth axis. In the gnathostatic casts, w e h a ve a 3. F ro m the eye-ear p la n e : reprod uction o f the denture th a t is an a (a) V e rtica l dim ension. tom ic in its en tirety to the three planes (b) F orm and an gle o f occlusal curve. m e n tio n e d : i. T h e upp er base is id en tical w ith (c) In clin atio n o f tooth axis. W ith the old-fashioned conventional the eye-ear plane o f the patien t. T h e m odels, w hich are m erely reproductions low er base is parallel to the upper. in the photostatic and roentgenostatic pictures.
HAWLEY
1
L C
GONIAL ANGLE M
P
SAQITTAl. PALATAL CURVE
TRANSVERSE PALATAL CURVE
TRANSVERSE PALATAL CURVE
SAOITTAL PALATAL CURVE
E - E -P
OCCLUSAL CURVE
OCCLUSAL CURVE
F ig . 5 .— G r a p h c h a rts s h o w in g n o rm p a tte r n s fo r 6, 12 a n d 18 years.
2. T h e anterior angles o f the bases coincide w ith the m edian plane. 3. T h e rig h t and left angles cor respond to the orbital plane. W ith the casts oriented in this m anner, a diagnostic stud y in relation to th e three planes w ill reveal the follow in g aspects : 1. F ro m the m edian plane : (a) T ran sverse sym m etry. (b ) A rch form . (c) P roportion o f w idth.
of teeth w ith ou t a n y relationship to skull structure, not on ly are these aspects obliterated, b u t also, in m an y cases, false representations o f existing conditions are visualized, w h ich doubtless prove m is lead in g in m an y cases. In F igu re 4, it w ill be noted th at the true an om aly o f a m arked asym m etrical developm ent was lost in the conventional m odel. T h e technic o f parallelin g the occlusal plane w ith the base presents a
W e in g a r t — “ K e y R id g e ” a s D i a g n o s t ic A id
condition that is rarely found in N ature. A s a m atter o f fa ct, the degree o f a n g u larity betw een the occlusal curve and the F ran kfo rt horizontal plane is abou t 11 fo r the right side and 13 for the left side and is rarely the same on the tw o sides. T h e diagnostic valu e o f the gnathostatic m odels increases im m easurably w hen th ey are properly scribed w ith the aid of the W aldron sym m etrograph and curve diagram s or graphs are prepared. T h ese curves are superim posed over in dicated norm patterns, w h ich serve as a diagnostic gu ide sim ilar to norm averages of w eight, height, etc. T h ree norm p a t terns are u s e d : 6, 12 and 18 years. T h is procedure is o f great value in
i 5 87
patient and th ey w ere cum bersom e for filing purposes. In the photostat, w hich is a p h oto graph w ith the head positioned in the horizontal plane, w e incorporate a c cu racy o f detail w ith sim plicity o f rep ro duction and obtain a fa cia l record w h ich is o f im m ense diagnostic value. In Figure 6, w e h ave a facial rep ro duction w hich supplem ents and is in h a r m ony w ith, the orientation o f the d en ture reproduction. W hen lines are draw n betw een the various cephalom etric points heretofore m entioned, such a photostat is m ost h elp fu l in analyzing and studying the features as they m ay va ry from the average norm .
Fig. 6.— Photostatic facial reproductions w ith diagnostic planes indicated.
com piling statistical d ata and, w hen sim ilarly recharted upon the com pletion o f treatm ent, offers conclusive evidence o f the actual changes that have been achieved. TH E PH O TO STA TIC RECORD
F rom the earliest days of orthodontics, photographs w ere used to record fa cia l disharm ony. T h a t these unrelated ph oto graphs w ere o f little diagnostic va lu e is evidenced b y the fa ct that they w ere dis carded in favor o f plaster masks. T h e ir construction was too arduous for the
A fixed focal distance, either onefourth or on e-half life-size, must be established and m aintained as a definite factor in the technic. W h en this is done, successive photostats o f patients taken du rin g treatm ent w ill h ave definite com p arative valu e in studying grow th changes resulting from treatm ent, p ar ticu larly o f the low er part o f the face, the so-called “ changeable area.” T H E ROENTGENOGRAPHIC RECORD
W e now have reproductions o f the denture and o f the fa ce w hich are re
i5 88
T h e J o u r n a l o f t h e A m e r ic a n D e n t a l A s s o c ia t io n
lated. A fu rth er record o f d en tofacial relations is obtained through the use o f cephalom etric roentgenogram s of the h ead w h ich show the orientation of the denture to the other fa cia l osseous stru c tures. H ere again, the various anatom ic landm arks are noted. It is now possible to take exact m easurem ents from the various planes d irectly on the bone and thus overcom e the weakness o f taking m easurements through the coverin g of soft tissues of unknow n thicknesses. In this m anner, the roentgenogram not only becomes a most valu able diagnostic aid, but, w hen taken serially, is also o f inesti-
tine procedure, needs no fu rth er com m ent. A w ell-rounded diagnostic study should also include a roentgenogram of the hand o f the developin g child. Th is w ill afford a study of the epiphysis, the ossification centers, the degree o f m in-
Fig. 8.— R oentgenogram of hand ; used for studying skeletal m aturation index.
Fig. 7.— Profile roentgenogram showing cephalom etric landm arks used to orient den ture to facial osseous structures.
m able value in studying and recording d en tofacial developm ental changes and checking the results o f orthodontic treat ment. Since the orthodontist is prim arily concerned w ith grow th and developm ent, d urin g w hich period the eruption o f teeth plays an im portant p art, the necessity fo r an x -ray series o f the ind ivid u al teeth, to gether w ith lateral ja w views, as a rou
Fig. 9.— M ax illa ry roentgenogram orients denture to “ key rid ge.”
w hich
eralization, etc. T hese roentgenogram s are checked w ith the h a n d standards of T o d d for norm al skeletal m aturation. T o com plete the diagnostic study, it
W e i n g a r t — “ K e y R i d g e ” a s D i a g n o s t i c A id
is essential to predeterm ine the exact positioning o f the ind ivid u al teeth in the skull. It rem ained fo r A tkin son to give us this missing link in the diagnostic chain, the “ key rid ge,” th at strong buttress o f bone w hich descends and goes forw ard from the zygom a to the m axillary bone and acts as a support for the m axillary first m olar. In the adult, the ridge lies d irectly over the mesiobuccal root o f the m axillary first m olar. A m a xillary roentgenogram presents an excellen t orientation o f the denture to the “ k ey ridge.” T h is view affords not on ly a detailed study o f the correct posi tioning o f the teeth in the skull, bu t also an excellen t study of arch form as re lated to the surrounding b on y structures. In m an y instances, the posterior palatine suture is also visible, w hich offers an a d ditional check fo r accuracy. d if f e r e n t ia l d ia g n o s is
W ith the foregoing gnathostatic, photostatic and roentgenostatic d ata at hand, a differential diagnosis o f the den ture, accord in g to the three planes as established, is p r e p a r e d : A . R elation o f the lateral halves to the m edian plane. 1. C on traction (T o o near to the m edian p la n e ). 2. D istraction (T o o fa r from the m edian p la n e ). B. R elation to the orbital plane. 1. Protraction (anterior to n orm al). 2. R etraction (posterior to n orm al). C . R elation to the horizontal plane. 1. A ttra ctio n (too close to the eye-ear p la n e). 2. A bstraction (too distant from the eye-ear p la n e ). D eviations are furth er classified as in cisal, lateral and total, in horizontal localization. V e rtica l localization is designated as dental, alveolar, m axillary and m andibular. Since it m ust be conceded that the denture is not an isolated b od y, b u t an anatom ic and physiologic part o f the
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head, it is not the intention o f this pres entation to elaborate fu rth er on the rela tive valu e o f a diagnostic procedure based upon cephalom etric investigations. C o n tra ry to m an y opinions, the p re paratory technic is not an arduous one. W ith a little experience, the takin g o f the impressions w ill consum e no m ore tim e than a n y other satisfactory im pres sion technic. T h e laboratory procedure, in fa ct, takes even less tim e than the trim m ing o f conventional m odels to artistic p rop ortion s; w h ile the prep ara tion o f the graphs can be delegated to an efficient assistant. Regardless o f the tim e elem ent in volved, an appreciation o f the valu e o f a gnathostatic technic as the basis o f a routine diagnostic procedure can be had only if one w ill ad opt its principles in practice. W e are indebted to R a lp h W aldron fo r his research and experim entation in this field. O n his original technic, these procedures are based. BIBLIO G R A PH Y
1. S i m o n , P. W .: Fundamental Principles of Systematic Diagnosis of Dental Anomalies. (Translated by B. E. Lischer.) Boston: The Stratford Co., 1926. 2. B r o a d b e n t , B. H .: New X -R ay T ech nique and Its Application to Orthodontia. Angle Orthodontist, 1:45, No. 1, 1931. 3. Idem : Bolton Standards and Technique in Orthodontic Practice. Angle Orthodontist, 7:209, No. 4, 1937. 4.. H i g l e y , L. B .: Head Positioner for Sci entific Radiographic and Photographic Pur poses. Internat. J. Orthodontia, 22:699, July
1936. 5 . L o w y , R ic h a r d : Diagnosis. Am. J. Orthodontics, 24:762, August 1938. 6. T o d d , T . W .: Record of Metabolism Im printed on Skeleton. Am. J. Orthodontics, 2 4 :8 n , September 1938. 7. Idem: Atlas of Skeletal Maturation. Part. 1. Hand. St. Louis: C . V . Mosby Co., 1937 8. M c C o y , J. D .: Applied Orthodontics. Ed. 4. Philadelphia: Lea & Febiger, 1935. 9. A t k i n s o n , S. R .: Strategy of O rtho dontic Treatment. J.A .D .A ., 24:560, April 1937119 West Fifty-Seventh Street.