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A cinefluorographic analysis of the temporomandibular joint
A cinefluorographic analysis of the temporomandibular joint
James H. McLeran, DDS, MS John C. Montgomery, DDS, MS Merle L. Hale, DDS, MS, Iowa City Cinefluorography provides a method to investigate the functioning temporomandibular joint. A study was made to determine or classify patterns of move ment of the normally functioning jo int to distin guish pathologically functioning joints. Modifica tions and improvements will make this technic more valuable in future studies.
The temporomandibular joint has been the subject of considerable interest and investigation for al most a century. One of the most complex of the fa cial structures, it produces many problems that are difficult to diagnose and treat.1 Even though this joint is a dynamic, functional entity, most studies concern its static anatomy.2 Usually anatomic dissections, static radiographic examinations, histologic technics, and electromy ography are used to investigate the temporoman dibular joint’s structure. The transformation of the results obtained from the analysis of these static studies into dynamically sound, functional con cepts has limitations. The primary limitation of static, standard radi1394
ographs is that they disclose only changes in the osseous structures.3 Since much of the function of the joint depends on its soft tissue components, radiographs do not show incipient or subtle changes in the temporomandibular joint or its function.3 It was thought that a more definitive basis for study and diagnosis might be the condylar excursions or patterns of movement that are most ly a result of the soft tissue components. Serial recording of the movements of the tem poromandibular joint may be accomplished by di rect radiography by use of roll film and various cassette changing devices or, indirectly, by pho tographing a fluorescent screen on which the mov ing object is reproduced by roentgen radiation. This method is termed direct cinefluorography.4*5 Proper exposure of the motion picture film re quires a fluorescent screen brightness of a certain magnitude, which results in high levels of radiation to the patient. This feature is hazardous to the pa tient, and the short strips of film obtained have limited usefulness.4’6 The development of an image-intensification apparatus that replaces an ordinary fluorescent screen has made possible more extensive investi gation of the functioning joint by use of cinefluor ography. By use of screen intensification, the image brightness required for recording move ments on film is obtained by electronic amplifica tion of the image produced by low levels of radi ation. This method is indirect cinefluorography.7 Several investigators4*6-9 have described general
observations o f the functioning tem porom andibu lar jo in t recorded by cinefluorographic technics. T he purpose o f this study, however, was to classi fy o r categorize the patterns of m ovem ent in the norm ally functioning tem porom andibular jo in t to distinguish pathologically functioning joints. To describe a jo in t as having norm al m ovem ent pat terns,6 it m ust first be shown th at clinically nor m al6 joints have distinguishable patterns o f m ove m ent th at are significantly distinctive from clin ically m alfunctioning joints.
Objectives T he objectives o f this study were as follows: ■ T o develop a methodology that would adapt available cinefluorographic equipm ent for a valid investigation o f the physiologic action o f the tem p orom andibular joint. This m ethodology would include standardization o f patient position and cinefluorographic technics; selection o f sensitive, reproducible film; developm ent of a m ethod for obtaining reproducible m easurem ents o f the struc tural positions from the individual cinefluorograph ic fram es, and developm ent o f a reliable analyzing procedure. All these m ethods would be within the safe range o f radiation for the subjects. ■ T o apply the m ethod of indirect cinefluoro graphic technic in filming a sam ple o f subjects with clinically norm al tem porom andibular joints. ■ T o collect and graph data to classify o r catego rize the patterns of the opening and closing m ove m ents o f the clinically norm al tem porom andibular joint.
Methods T he cinefluorographic equipm ent used (Fig. 1) was designed by the N orth A m erican Phillips Com pany. M ajor com ponents o f this equipm ent include a R otalix 125 kilovolt peak X -ray tube w ith a rotating anode and a line focus o f 0.3 mm. and a Phillips 5 -inch im age-intensifier tube with an intensification factor o f 800 to 1,000.4 This intensifier tube is fixed to direct the beam o f the X ray to the center o f the screen. A fluoroscopic view er and an A uricon 16-mm. movie cam era are also com ponent parts. T he pow er was supplied to the X -ray tube by a McLeran—1\
Fig. 1 ■ Equipment and subject positioning. Components of apparatus include: X-ray head, 1; image intensifier unit, 2; fluoroscopic screen, 3; fluoroscopic viewer, 4; motion pic ture camera, 5, and head positioner, 6.
M onoray 100 kilovolt peak generator th at sup plies constant radiation when activated. A m odi fied Higley head positioner10 and a standard head rest were used to im m obilize the subject’s head. T he head positioner was suspended from the ceil ing and consisted o f bilateral earposts covered with a soft gum rubber and hard rubber frontpiece. A reference wire cross was attached to the earpost. This w ire cross was placed with the vertical posi tion perpendicular to the floor and the horizontal position parallel to the floor. T he im age of this w ire cross was used as a standard reference for graphic m easurem ents when the film was ana lyzed. Subjects were seated in the Phillips dental chair, and their heads w ere fixed by use o f earposts and nosepieces, with the m idsagittal plane 8.5 inches from the screen o f the image intensifier to allow an object-film distance o f about 5 inches. This pro cedure, in providing for an upright position of the head, fulfills a vital criterion in establishing the uninhibited and m ost natural movem ents o f the m andible. The final position accepted is sim ilar to the U pdegrave3 technic that is reported by Z ech11 to be superior to the other commonly used radiographic technics in the determ ination of the mobility of the condyle, its relationship with the fossa, and its relationship to the em inentia during the m andibular excursions. F inal positioning o f ry—Hale: CINEFLUOROGRAPHIC ANALYSIS OF TMJ ■ 1395
the patient was by direct viewing o f the fluoro scopic im age before the filming o f the sequence o f m andibular movements. G enerator settings o f 95 kilovolts and about 17 m illiam ps w ere the m ost satisfactory for the single-fram e image observation requirem ents. M il livolt readings were used to indicate image inten sity. O ptim al results w ere obtained with a m illi volt reading of 1.5 to 1.8. A 2-mm. alum inum filter produced the best image quality with a m inim um of radiation to the subject. M axim al radiation exposure possible to the sub jec t was determ ined for the equipm ent used o p er ating w ithin the settings previously discussed. It was calculated at 8.86 roentgens per m inute, giv ing a m ean m axim um dosage o f 11.5 roentgens while film ing 32 subjects. K odak im proved Linograph Shellburst film was selected after com parative tests w ith three oth er types o f film stock. G rain and contrast q ual ities were the critical factors in selection o f film stock.
Selection o f subjects Subjects w ere selected to form a norm al sample. T he criteria w ere that they have clinically asym p tom atic joints; have A ngle’s Class I type occlusion, and have at least 28 teeth in occlusion. T he sub jects were placed through a sequence o f m ove m ents w hile the jo in t action was recorded on film. T his sequence consisted of four series of m ove
ments that were synchronized and audibly recorded on the sound track while the jo in t action was filmed. In these series, there w ere 12 specific po sitions for m axim um extrem es o f a particular move m ent th at were m arked on the sound track for future identification to facilitate analysis o f these positions. This m arking was accom plished w ith a m etal clicker as the signal when the subject had reached the m axim um of a particular m otion or position. This sequence was carried out on both joints o f each subject and film ed a t 24 fram es per second. T he am ount o f footage film ed per subject varied from less than 50 feet to m ore than 75 feet.
A nalysis o f film In this study, 66 subjects (35 norm al, 13 edentu lous, and 18 abnorm al or pathologic) were filmed. The film was edited and prepared for m easure m ent. T here w ere 4,762 tracings o f 132 joints available for analysis. Twenty joints classified as norm al were selected at random for a fram e-byfram e analysis for this study o f the opening and closing m ovements only. The positive print of the films was so edited that the films o f one subject w ere on one roll. Splicing and editing procedures w ere accom plished on a hand-operated film editor with viewer and sound reproductions synchronized. This editor al lowed the operator to view the film at any speed from one fram e at a tim e to a speed in excess of the actual filming speed. W ax crayon was used to m ark the indicated fram es, the beginning and end o f the opening and closing movements. A n allow ance was m ade when m arking the individual fram es to com pensate for the inherent delay be tween the sound and the photographic image, which was a particular constant for any one roll of film but varied slightly for each roll.
Tracing and measuring
Fig. 2 ■ Projection analysis apparatus. 1396 ■ JADA, Vol. 75, Dec. 1967
T he apparatus used for tracing and m easuring con sisted o f Bell & Howell tim e and m otion study pro jecto r and a 0.25-inch Plexiglas tracing surface m ounted on a steel fram e (Fig. 2). T he distance between the Plexiglas screen and the projector could be adjusted by sliding the projector along the common steel fram e. T his adjustm ent was cal culated by m easuring the image o f the 2-cm. stain less steel pin th at was placed over the skin in the region of the jo in t at the time o f filming the se-
Fig. 3 ■ Two frames taken from film strip of left. Note im ages of wire cross reference lines and 2-cm. stainless steel pin. Image of glenoid fossa and condyle have been traced.
quence. T he film was projected at varying speeds from single fram e to full speed viewing for this 24-fram e per second film speed. The image was projected through the Plexiglas screen onto the tracing paper that was clam ped onto the tracing surface side opposite the projec tor. By projecting the image through the Plexiglas onto the side opposite the projector, the investi gator had free, unham pered w orking area for trac ing or direct m easuring w ithout interfering with the image projection. M easurem ents were then m ade directly on the image that was projected on a clear p rin t tracing paper covering the Plexiglas screen. Figure 3 is a reproduction o f two fram es o f the cinefluorographic films of one subject. It shows the images o f the 2-cm. stainless steel pin and the w ire cross reference superim posed on the image o f the joint. M easurem ents m ade in this procedure are shown diagram m atically in Figure 4. All m easurem ents
w ere made from the perpendicular to the horizon tal and vertical reference lines. T hese reference lines represent the images m ade on the film by the reference w ire cross attached to the earpost of the head positioner during the filming procedure. These perpendicular reference lines are for orien tation only. It is not suggested that they rem ained constant from one subject to another nor th at abso lute m easurem ents may be obtained from subject to subject. They w ere used in this study to estab lish planes from which to m easure different posi tions and thereby obtain relative data that may be com pared from subject to subject. T his com par ison is possible since the position o f these lines should rem ain constant during the film ing se quence o f any one joint. Before the fram e-by-fram e statistical analysis of each opening and closing m ovem ent sequence, P oint B (the point o f greatest convexity on the image of the articular eminence) and P oint C (the point o f greatest concavity on the image o f the depth o f the fossa) were established (Fig. 4) by re cording m easurem ents 3, 4, 5, and 6. These points w ere m ade constant for each jo in t and were used later as reference points in graphing the pattern of movement. M easurem ents 1 and 2 w ere m ade to establish P oint A (the point o f greatest convexity on the image of the height of the condyle). T he charting of this point on graph p ap er later in the study will outline the pattern o f m ovem ent o f the condyle. The establishm ent o f this point was m ade in each fram e throughout the opening and closing se quence. A lthough establishm ent o f this point was not difficult near the two extrem es o f m ovem ent (occlusion and m axim um open or maximum closed), it was often m ore difficult to establish this point in the m iddle of a sequence when move m ent was m ost rapid because o f loss o f definition. R epeated random m easurem ents were m ade to confirm the reliability o f m easuring these points. These m easurem ents were close to initial m easure ments and varied not m ore than 0.5 mm. M easure m ents obtained from the film s were recorded by subject num ber on data sheets. To transfer the data obtained from the cine fluorographic film into a form for analysis, a graph ing procedure was carried out on a scale o f 1 to 5. T his enlargem ent o f the pattern facilitated com parisons. M easurem ents from each fram e o f a par ticular jo in t were plotted on a graph and joined in succeeding order by a solid straight line to give a pattern of m ovem ent described by the image of the most anterior-superior point on the articular surface o f the condyle. T he points representing
McLeran—Montgomery—Hale: CINEFLUOROGRAPHIC ANALYSIS OF TMJ ■ 1397
II5
6
R
3
H O R IZ O N T A L
i» » J
H O R IZ O N T A L
(ntml
Fig. 5 ■ Representative samples of plotted graphs of con dylar movement. Patterns show some zigzag characteristics and movement beyond eminentia.
the image of the depth of the fossa (c) and the image of the height of the convexity of the emi nence were plotted and joined by a curved broken line representative of these two structures. This sketch of the superior articulating fossa and emi nence was not intended to be an accurate repro duction of these structures but rather to be used for orientation purposes. Figure 5 shows representative samples of these graphs. Each plotted point on the pattern of move ment is, in most instances, representative of one frame. In some instances, however, when there was no movement from one frame to the next, they represent two or more frames, especially in the extremes of movement. Statistical analysis of the reliability of the mea suring error gave a Pearson correlation coefficient of 0.95 to 0.98 for each of the eight measurements made. This process was done by repeated measure ment of random frames at three individual settings. Graph analysis To describe these graphs of the patterns of move ment taken by the condyle in this group of normal subjects, certain measurements were made. It was hoped that these measurements could be used as 1398 ■ JADA, Vol. 75, Dec. 1967
Fig. 6 ■ Measurements for analysis.
standards for this technic by which the studies of the pathologic temporomandibular joint could be compared. Attempts were also made to categorize these patterns by some common characteristic. Measurements were analyzed to determine the ranges, means, and standard deviations. In Figure 6, the measurements made are diagrammatically su perimposed on the graph of one of the joints from the study. Measurements made were as follows: ■ Total condylar movement was made in a down ward and forward direction. For this study, total condylar movement was calculated on a straight line from the most posterior-superior point to the most anterior-inferior point of the pattern of move ment. This measurement had a mean of 14.3 mm. with ranges from 10 to 20 mm. ■ Horizontal movement was the total movement of the condyle in a forward direction. This move ment was determined by measuring the distance between two parallel vertical lines drawn through the most posterior point and the most anterior point on the pattern. The range for horizontal movement was from 7 to 20.5 mm. with a mean of 12.4 mm. ■ Vertical movement was the total movement of
the condyle in a downward direction. This move ment was measured between parallel lines drawn horizontally through the most superior point and the most inferior point on the pattern. Vertical movement ranged from 5 to 9.5 mm. with a mean of 7.1 mm. ■ Condyle-eminence distance was the distance be tween the nearest point on the pattern to the point representing the eminence. The range for this dis tance was 1.0 to 5.0 mm. with a mean of 2.8 mm. ■ Condyle-fossa distance was the distance between the nearest point on the pattern to the point repre senting the depth of the fossa. The range for this distance was 1.0 to 8.0 mm. with a mean of 3.7 mm. H O R IZO N TAL
■ Fossa-eminence distance was the depth of the fossa or the height of the eminence, the distance between two parallel lines drawn horizontally through the points representing these two struc tures. The range of this depth was 3.0 to 10.0 mm. with a mean of 6.3 mm. ■ Angle of pattern of movement downward and forward was determined by drawing a straight line through the most posterior-superior point on the pattern to the most anterior-inferior point on the pattern nearest the point representing the image of the articular eminence. The angle this line made as it intersected a horizontal line through the point representing the image of the depth of the fossa was determined as the angle of pattern of move ment. Although this criterion for selecting the an terior point of the pattern necessitated omitting part of the anterior pattern in many instances, it seemed that this angle would be most representa tive of the predominant downward and forward movement. This angle ranged from 15 degrees to 48 degrees and had a mean of 31.5 degrees for this group of 20 joints. ■ Angle of eminence to fossa was made by a line drawn between the point representing the articu lar eminence and the depth of fossa as it inter sected the same horizontal line mentioned in the previous angle determination. This angle had a range of 14 degrees to 39 degrees and a mean an gle of 28.6 degrees. ■ Relation of condylar movement to eminence was the relationship between the extent of ante rior condylar movement and articular eminence
( rnm)
H O R IZ O N T A L
(m m )
Fig. 7 ■ Representative samples of plotted graphs show up ward turn beyond eminentia.
and was calculated by noting the position of the most anterior point on the pattern and a line drawn perpendicular to the point representing the image of the height of the eminence. In this relationship, the joints were placed in one of two classes: Class A joints were those that showed a pattern of move ment that moved anterior to the height of the emi nence; Class B joints were those whose patterns stopped posterior or reached the image of the point representing the height of the eminence. Seventy percent of the joints were classified in Class A, and the remaining 30 percent were des ignated as Class B. The incisal-to-incisal maximum opening mea sured before filming the subject was also recorded. This measurement of maximum incisal opening had a range of 33 to 54 mm. with a mean of 42.1 mm. Standard deviation was 7.8. This measure ment was recorded primarily for the determina tion of the condylar movement to incisal opening ratio. Since the ratio of condylar movement to in cisal opening has been recorded in other studies,12 it was thought that the determination of this ratio in the present study would be interesting. This ra tio Was determined by dividing the maximum in cisal opening by the total condylar movement. The range in this ratio was from 1.9:1.0 to 4.8:1.0 with a mean ratio of 3.0:1.0. The frames measured as involved in the open ing and closing movements were recorded. The frame consumption ranged from 10 to 28 with a
McLeran—Montgom ery—Hale: CINEFLUOROGRAPHIC ANALYSIS OF TMJ ■ 1399
Table ■ Sum m ary o f data obtained fro m graphs. Measurement
Range
Mean
Total condylar movement 10.0-20.0 mm. 14.3 mm. Horizontal movement 7.0-20.5 mm. 12.4 mm. Vertical movement 5.0* 9.5 mm. 7.1 mm. Condyle eminence 1.0- 5.0 mm. 2.8 mm. Condyle fossa 1.0- 8.0 mm. 3.7 mm. 3.0-10.0 mm Fossa eminence 6.3 mm. Angle of movement 15°-48° 31.5® Angle o f eminence to fossa 14°-39° 28.6° Maximum incisal opening 33.0-54.0 mm. 42.1 mm. Totol movement to incisal 1.9-1 to 4.8-1 3-1 opening ration Frames in movement 10-28 17.1 Rotation o f condylar movement fo eminence Class A (beyond eminence)...........14 Class B (stops at or posterior to eminence)...........6
SD* 3.2 3.7 1.3 1.1 1.7 1.7 (not determined) (not determined) 7.8 (not determined! (not determined!
*SD = Stondard deviation.
mean frame consumption of 17. Data from this measurement yielded the most bilateral symmetry from subject to subject. A summary of the pertinent data calculated from the main graph measurements is presented in the Table. These measurements are valid for this particular method only. They are not intended as absolute measurements. They will be useful for other investigators in comparison studies that use film obtained from these same angulations and technics.
Discussion
It appears from the results of the study that the pattern of movement of each joint during the open ing and closing movements may vary enough to make it difficult to classify or categorize the nor mally functioning temporomandibular joints. There was a wide variance in individual patterns as shown on the graphs, which would have been difficult to surmise by only observing the projected films as several authors7’ 12*13 have done in their reports. The pattern of movement of the joints was down ward and forward and generally described a curved line with the concavity in a superior direction toward the eminentia. If the path continued be yond the eminentia, it generally took an upward turn as it proceeded forward. This upward turn was seen in joints 166 right, 107 right, 107 left, 125 right, and 125 left, whose patterns are shown in Figure 7. Although others7 have noted a slight horizontal plateau between the end of the hinge axis and the start of the downward and forward glide of the condyle, this feature was not consis tently noted in this study. Consistent with other studies,7 however, an uneven and an irregular path of movement was noted. 1400 ■ JADA, Vol. 75, Dec. 1967
When the points of each successive frame were plotted and connected, the result was a zigzag line in most of the graphs. This zigzag pattern may be partially a result of the inherent error in reading and plotting. There may also be other factors that are important. There is vital importance in the in teraction of the muscles making up the muscular complex that is responsible for the opening and closing movements. Therefore, the zigzag motion might be a result of the interaction of several mus cles as their contraction starts, stops, increases, or diminishes. It is possible that these movements are exaggerated in abnormal joint analysis. The degree of this zigzag characteristic varied for each joint in one subject as well as for the same joint in all subjects. The pronounced degree of irregularity in the pattern of 115 left and the almost smooth pattern in 115 right, which are right and left pat terns of the same subject, are shown in Figure 5 . Many of the patterns of the joints in this study do not support Craddock’s conclusion that “Condy lar movements within the functional range are normally congruent with the fossa outline and maintain a constant separation of about 2 mm. on the articular surface of the glenoid fossa.”13 If indi vidual frames were taken at occlusion, rest, and maximum opening, however, in some static radi ographic studies, 2»7*13-18 this false conclusion could be made. It would appear that any conclu sion that a “Lack of congruency of movement es tablishes prima facie evidence of atypical func tion”13 cannot be supported. Many investigators question whether in the nor mally functioning temporomandibularjoint,thecondylar head moves anterior to the crest of the articu lar eminence in the opening movement.3»6»13*14»17 Some define this as a hypermobile joint. Other investigators think that the normal opening range of the condyle allows it to move anterior to the eminence.2»12*18*19 Results of this study tend to sup port the conclusion that the condyle may normally move anterior to the crest of the eminence since it occurred in 70 percent of the joints that were graphed (Fig. 5, 8). Some investigators12 have concluded that in cisal openings of as much as or less than 35 mm. were never accompanied by excursion of the con dyle beyond the crest of the eminence. In this study, however, in the subjects with 35 mm. or less of incisal opening, 30 percent of these patterns did exceed the point representing the height of the eminence. The ratio of total condylar movement to incisal opening in this study was found to have a mean of 3:1, which compares with other studies with
th e ranges o f as m uch as 6:1. T hese m easurem ents have lim ited value, an d these statistical sum m a ries should not be accepted o r used as absolute m easurem ents. They a re valid only for use in com parison studies th a t use the sam e angulations and technics prim arily because o f a distortion o f anat om y and m ovem ent caused by the angulation and the tw o-dim ensional ch aracter o f the picture.
ifications and im provem ents will m ake it m ore valuable in future studies.
The authors thank Donald S. Dana and Ronald H. Wilkison for their participation in the original research. Doctors McLeran, Montgomery, and Hale are at the Uni versity of Iowa, Iowa City, where Doctors McLeran and Mont gomery are assistant professors and Doctor Hale is a profes sor and head of the department of oral surgery.
Conclusions T he devised m ethod fo r th e use of indirect cinefluorography fo r the investigation o f the tem poro m andibular jo in t appears to offer a m ethod for th e analysis o f the functioning m ovem ents o f the joint. A ttem pts to describe the patterns o f m ovem ent in specific categories o r classes were not successful in this study prim arily because o f the extensive variations in the individual patterns. T his v aria tion existed from subject to subject and from jo in t to joint. A zigzag m ovem ent o f the image o f the condyle was consistently observed. T h e theory th at this pattern m ay be a result o f the individual actions o f the different m uscles controlling the excursion o f the jo in t was suggested. T he p attern o f the condyle did m ove in a dow n w ard and forw ard direction w ith the concavity upw ard during th e opening m ovem ent. W hether this variable m ovem ent p attern w ith the concavity upw ard is enough variation in pathologic joints to m ake them distinctive from norm al jo in ts is not known. In this study, th e condyle did not appear to necessarily assum e a p a th congruent w ith the fossa outline in the articular surface o f the glenoid fossa. If the group from w hich the sam ple for this study was taken can be accepted as norm al, it would appear th a t the norm al physiologic range o f the tem porom andibular jo in t does allow for the m ovem ent o f th e condylar h ead anterior to the eminence. Excursion o f th e condyle beyond the crest o f the em inence was observed in 30 percent o f the subjects w ith as m uch as o r less than 35 mm. o f incisal-to-incisal opening. It w ould ap p ear th at indirect cinefluorography is an excellent and heretofore unequaled technic for th e study o f the tem porom andibular joint. M od
1. Henny, F. A. The temporomandibular joint. In Kruger, G. 0. (ed.). Textbook of oral surgery. St. Louis, C. V. Mosby Co., 1959, p. 356-372. 2. Ricketts, R. M. Laminagraphy in the diagnosis of temporomandibular jo in t disorders. JADA 46:620 June, 1953 3. Updegrave, W. J. Evaluation of temporomandibular jo in t roentgenography. JADA 46:408 April, 1953. 4. Berry, H. M., Jr., and Hofmann, F. A. Preliminary work on cinefluorography with image intensification, in the study of the temporomandibular joint. Oral Surg 10:63 Jan., 1957. 5. Lindblom, Gosta. Anatomy and function of the tem poromandibular joint. Acta Odont Scand (suppl. 28) 17:7, 1960. 6. Lindblom, Gosta. A cineradiographic study of the tem poromandibular joint. Acta Odont Scand 15:141 May, 1957. 7. Berry, H. M., and Hofmann, F. A. Cineradiographic observations of temporomandibular jo in t function. J Prosth Dent 9:21 Jan.-Feb., 1959. 8. Berry, H. M., and Hofmann, F. A. Cinefluorography with image intensification for observing temporomandibular jo in t movements. JADA 53:517 Nov., 1956. 9. Quartararo, I. N., and Zambito, R. F. A preliminary report on the investigation of the possible use of cinefluoro graphic techniques for the study of the temporomandibular joint. New York J Dent 10:215 April, 1952. 10. Higley, L. B. A head positioner for scientific radiographic and photographic purposes. Orthodont Oral Surg Int J 22:699, 1936. 11. Zech, J. M. Comparison and analysis of three tech niques of taking roentgenograms of the temporomandibular joint. JADA 59:725 Oct., 1959. 12. Markowitz, H. A., and Gerry, R. G. Temporomandib ular jo int disease. Oral Surg 2:1309 Oct., 1949. 13. Craddock, F. W. Radiography of the temporomandib ular joint. J Dent Res 32:302 June, 1953. 14. Blackman, Sydney. Serial arthro-radiography for the examination of the temporomandibular joints. Dent Pract (Bristol) 8:227 April, 1957. 15. Donovan, R. W. Method of temporomandibular joint roentgenography for serial and m ultiple records. JADA 49: 401 Oct., 1954. 16. Lawther, W. L. Roentgenograph ic study of the tem poromandibular joint, using a special head positioner. Angle Orthodont 26:22 Jan., 1956. 17. Shore, N. A. Interpretation of the temporomandibu lar jo in t roentgenograms. Oral Surg 13:341 March, 1960. 18. White, T. C.; Campbell, J., and Anderson, H. Layer radiography in temporomandibular jo in t examination. Dent Record 92:49 March, 1957. 19. Bell, W. E. Temporomandibular jo in t disease; a teach ing manual for students and practitioners of dentistry. Dallas, Texas, Egan Co., 1960.
M cLeran—M ontgom ery—Hale: CINEFLUOROGRAPHIC ANALYSIS OF TMJ ■ 1401
James H. McLeran, DDS, MS John C. Montgomery, DDS, MS Merle L. Hale, DDS, MS, Iowa City Cinefluorography provides a method to investigate the functioning temporomandibular joint. A study was made to determine or classify patterns of move ment of the normally functioning jo int to distin guish pathologically functioning joints. Modifica tions and improvements will make this technic more valuable in future studies.
The temporomandibular joint has been the subject of considerable interest and investigation for al most a century. One of the most complex of the fa cial structures, it produces many problems that are difficult to diagnose and treat.1 Even though this joint is a dynamic, functional entity, most studies concern its static anatomy.2 Usually anatomic dissections, static radiographic examinations, histologic technics, and electromy ography are used to investigate the temporoman dibular joint’s structure. The transformation of the results obtained from the analysis of these static studies into dynamically sound, functional con cepts has limitations. The primary limitation of static, standard radi1394
ographs is that they disclose only changes in the osseous structures.3 Since much of the function of the joint depends on its soft tissue components, radiographs do not show incipient or subtle changes in the temporomandibular joint or its function.3 It was thought that a more definitive basis for study and diagnosis might be the condylar excursions or patterns of movement that are most ly a result of the soft tissue components. Serial recording of the movements of the tem poromandibular joint may be accomplished by di rect radiography by use of roll film and various cassette changing devices or, indirectly, by pho tographing a fluorescent screen on which the mov ing object is reproduced by roentgen radiation. This method is termed direct cinefluorography.4*5 Proper exposure of the motion picture film re quires a fluorescent screen brightness of a certain magnitude, which results in high levels of radiation to the patient. This feature is hazardous to the pa tient, and the short strips of film obtained have limited usefulness.4’6 The development of an image-intensification apparatus that replaces an ordinary fluorescent screen has made possible more extensive investi gation of the functioning joint by use of cinefluor ography. By use of screen intensification, the image brightness required for recording move ments on film is obtained by electronic amplifica tion of the image produced by low levels of radi ation. This method is indirect cinefluorography.7 Several investigators4*6-9 have described general
observations o f the functioning tem porom andibu lar jo in t recorded by cinefluorographic technics. T he purpose o f this study, however, was to classi fy o r categorize the patterns of m ovem ent in the norm ally functioning tem porom andibular jo in t to distinguish pathologically functioning joints. To describe a jo in t as having norm al m ovem ent pat terns,6 it m ust first be shown th at clinically nor m al6 joints have distinguishable patterns o f m ove m ent th at are significantly distinctive from clin ically m alfunctioning joints.
Objectives T he objectives o f this study were as follows: ■ T o develop a methodology that would adapt available cinefluorographic equipm ent for a valid investigation o f the physiologic action o f the tem p orom andibular joint. This m ethodology would include standardization o f patient position and cinefluorographic technics; selection o f sensitive, reproducible film; developm ent of a m ethod for obtaining reproducible m easurem ents o f the struc tural positions from the individual cinefluorograph ic fram es, and developm ent o f a reliable analyzing procedure. All these m ethods would be within the safe range o f radiation for the subjects. ■ T o apply the m ethod of indirect cinefluoro graphic technic in filming a sam ple o f subjects with clinically norm al tem porom andibular joints. ■ T o collect and graph data to classify o r catego rize the patterns of the opening and closing m ove m ents o f the clinically norm al tem porom andibular joint.
Methods T he cinefluorographic equipm ent used (Fig. 1) was designed by the N orth A m erican Phillips Com pany. M ajor com ponents o f this equipm ent include a R otalix 125 kilovolt peak X -ray tube w ith a rotating anode and a line focus o f 0.3 mm. and a Phillips 5 -inch im age-intensifier tube with an intensification factor o f 800 to 1,000.4 This intensifier tube is fixed to direct the beam o f the X ray to the center o f the screen. A fluoroscopic view er and an A uricon 16-mm. movie cam era are also com ponent parts. T he pow er was supplied to the X -ray tube by a McLeran—1\
Fig. 1 ■ Equipment and subject positioning. Components of apparatus include: X-ray head, 1; image intensifier unit, 2; fluoroscopic screen, 3; fluoroscopic viewer, 4; motion pic ture camera, 5, and head positioner, 6.
M onoray 100 kilovolt peak generator th at sup plies constant radiation when activated. A m odi fied Higley head positioner10 and a standard head rest were used to im m obilize the subject’s head. T he head positioner was suspended from the ceil ing and consisted o f bilateral earposts covered with a soft gum rubber and hard rubber frontpiece. A reference wire cross was attached to the earpost. This w ire cross was placed with the vertical posi tion perpendicular to the floor and the horizontal position parallel to the floor. T he im age of this w ire cross was used as a standard reference for graphic m easurem ents when the film was ana lyzed. Subjects were seated in the Phillips dental chair, and their heads w ere fixed by use o f earposts and nosepieces, with the m idsagittal plane 8.5 inches from the screen o f the image intensifier to allow an object-film distance o f about 5 inches. This pro cedure, in providing for an upright position of the head, fulfills a vital criterion in establishing the uninhibited and m ost natural movem ents o f the m andible. The final position accepted is sim ilar to the U pdegrave3 technic that is reported by Z ech11 to be superior to the other commonly used radiographic technics in the determ ination of the mobility of the condyle, its relationship with the fossa, and its relationship to the em inentia during the m andibular excursions. F inal positioning o f ry—Hale: CINEFLUOROGRAPHIC ANALYSIS OF TMJ ■ 1395
the patient was by direct viewing o f the fluoro scopic im age before the filming o f the sequence o f m andibular movements. G enerator settings o f 95 kilovolts and about 17 m illiam ps w ere the m ost satisfactory for the single-fram e image observation requirem ents. M il livolt readings were used to indicate image inten sity. O ptim al results w ere obtained with a m illi volt reading of 1.5 to 1.8. A 2-mm. alum inum filter produced the best image quality with a m inim um of radiation to the subject. M axim al radiation exposure possible to the sub jec t was determ ined for the equipm ent used o p er ating w ithin the settings previously discussed. It was calculated at 8.86 roentgens per m inute, giv ing a m ean m axim um dosage o f 11.5 roentgens while film ing 32 subjects. K odak im proved Linograph Shellburst film was selected after com parative tests w ith three oth er types o f film stock. G rain and contrast q ual ities were the critical factors in selection o f film stock.
Selection o f subjects Subjects w ere selected to form a norm al sample. T he criteria w ere that they have clinically asym p tom atic joints; have A ngle’s Class I type occlusion, and have at least 28 teeth in occlusion. T he sub jects were placed through a sequence o f m ove m ents w hile the jo in t action was recorded on film. T his sequence consisted of four series of m ove
ments that were synchronized and audibly recorded on the sound track while the jo in t action was filmed. In these series, there w ere 12 specific po sitions for m axim um extrem es o f a particular move m ent th at were m arked on the sound track for future identification to facilitate analysis o f these positions. This m arking was accom plished w ith a m etal clicker as the signal when the subject had reached the m axim um of a particular m otion or position. This sequence was carried out on both joints o f each subject and film ed a t 24 fram es per second. T he am ount o f footage film ed per subject varied from less than 50 feet to m ore than 75 feet.
A nalysis o f film In this study, 66 subjects (35 norm al, 13 edentu lous, and 18 abnorm al or pathologic) were filmed. The film was edited and prepared for m easure m ent. T here w ere 4,762 tracings o f 132 joints available for analysis. Twenty joints classified as norm al were selected at random for a fram e-byfram e analysis for this study o f the opening and closing m ovements only. The positive print of the films was so edited that the films o f one subject w ere on one roll. Splicing and editing procedures w ere accom plished on a hand-operated film editor with viewer and sound reproductions synchronized. This editor al lowed the operator to view the film at any speed from one fram e at a tim e to a speed in excess of the actual filming speed. W ax crayon was used to m ark the indicated fram es, the beginning and end o f the opening and closing movements. A n allow ance was m ade when m arking the individual fram es to com pensate for the inherent delay be tween the sound and the photographic image, which was a particular constant for any one roll of film but varied slightly for each roll.
Tracing and measuring
Fig. 2 ■ Projection analysis apparatus. 1396 ■ JADA, Vol. 75, Dec. 1967
T he apparatus used for tracing and m easuring con sisted o f Bell & Howell tim e and m otion study pro jecto r and a 0.25-inch Plexiglas tracing surface m ounted on a steel fram e (Fig. 2). T he distance between the Plexiglas screen and the projector could be adjusted by sliding the projector along the common steel fram e. T his adjustm ent was cal culated by m easuring the image o f the 2-cm. stain less steel pin th at was placed over the skin in the region of the jo in t at the time o f filming the se-
Fig. 3 ■ Two frames taken from film strip of left. Note im ages of wire cross reference lines and 2-cm. stainless steel pin. Image of glenoid fossa and condyle have been traced.
quence. T he film was projected at varying speeds from single fram e to full speed viewing for this 24-fram e per second film speed. The image was projected through the Plexiglas screen onto the tracing paper that was clam ped onto the tracing surface side opposite the projec tor. By projecting the image through the Plexiglas onto the side opposite the projector, the investi gator had free, unham pered w orking area for trac ing or direct m easuring w ithout interfering with the image projection. M easurem ents were then m ade directly on the image that was projected on a clear p rin t tracing paper covering the Plexiglas screen. Figure 3 is a reproduction o f two fram es o f the cinefluorographic films of one subject. It shows the images o f the 2-cm. stainless steel pin and the w ire cross reference superim posed on the image o f the joint. M easurem ents m ade in this procedure are shown diagram m atically in Figure 4. All m easurem ents
w ere made from the perpendicular to the horizon tal and vertical reference lines. T hese reference lines represent the images m ade on the film by the reference w ire cross attached to the earpost of the head positioner during the filming procedure. These perpendicular reference lines are for orien tation only. It is not suggested that they rem ained constant from one subject to another nor th at abso lute m easurem ents may be obtained from subject to subject. They w ere used in this study to estab lish planes from which to m easure different posi tions and thereby obtain relative data that may be com pared from subject to subject. T his com par ison is possible since the position o f these lines should rem ain constant during the film ing se quence o f any one joint. Before the fram e-by-fram e statistical analysis of each opening and closing m ovem ent sequence, P oint B (the point o f greatest convexity on the image of the articular eminence) and P oint C (the point o f greatest concavity on the image o f the depth o f the fossa) were established (Fig. 4) by re cording m easurem ents 3, 4, 5, and 6. These points w ere m ade constant for each jo in t and were used later as reference points in graphing the pattern of movement. M easurem ents 1 and 2 w ere m ade to establish P oint A (the point o f greatest convexity on the image of the height of the condyle). T he charting of this point on graph p ap er later in the study will outline the pattern o f m ovem ent o f the condyle. The establishm ent o f this point was m ade in each fram e throughout the opening and closing se quence. A lthough establishm ent o f this point was not difficult near the two extrem es o f m ovem ent (occlusion and m axim um open or maximum closed), it was often m ore difficult to establish this point in the m iddle of a sequence when move m ent was m ost rapid because o f loss o f definition. R epeated random m easurem ents were m ade to confirm the reliability o f m easuring these points. These m easurem ents were close to initial m easure ments and varied not m ore than 0.5 mm. M easure m ents obtained from the film s were recorded by subject num ber on data sheets. To transfer the data obtained from the cine fluorographic film into a form for analysis, a graph ing procedure was carried out on a scale o f 1 to 5. T his enlargem ent o f the pattern facilitated com parisons. M easurem ents from each fram e o f a par ticular jo in t were plotted on a graph and joined in succeeding order by a solid straight line to give a pattern of m ovem ent described by the image of the most anterior-superior point on the articular surface o f the condyle. T he points representing
McLeran—Montgomery—Hale: CINEFLUOROGRAPHIC ANALYSIS OF TMJ ■ 1397
II5
6
R
3
H O R IZ O N T A L
i» » J
H O R IZ O N T A L
(ntml
Fig. 5 ■ Representative samples of plotted graphs of con dylar movement. Patterns show some zigzag characteristics and movement beyond eminentia.
the image of the depth of the fossa (c) and the image of the height of the convexity of the emi nence were plotted and joined by a curved broken line representative of these two structures. This sketch of the superior articulating fossa and emi nence was not intended to be an accurate repro duction of these structures but rather to be used for orientation purposes. Figure 5 shows representative samples of these graphs. Each plotted point on the pattern of move ment is, in most instances, representative of one frame. In some instances, however, when there was no movement from one frame to the next, they represent two or more frames, especially in the extremes of movement. Statistical analysis of the reliability of the mea suring error gave a Pearson correlation coefficient of 0.95 to 0.98 for each of the eight measurements made. This process was done by repeated measure ment of random frames at three individual settings. Graph analysis To describe these graphs of the patterns of move ment taken by the condyle in this group of normal subjects, certain measurements were made. It was hoped that these measurements could be used as 1398 ■ JADA, Vol. 75, Dec. 1967
Fig. 6 ■ Measurements for analysis.
standards for this technic by which the studies of the pathologic temporomandibular joint could be compared. Attempts were also made to categorize these patterns by some common characteristic. Measurements were analyzed to determine the ranges, means, and standard deviations. In Figure 6, the measurements made are diagrammatically su perimposed on the graph of one of the joints from the study. Measurements made were as follows: ■ Total condylar movement was made in a down ward and forward direction. For this study, total condylar movement was calculated on a straight line from the most posterior-superior point to the most anterior-inferior point of the pattern of move ment. This measurement had a mean of 14.3 mm. with ranges from 10 to 20 mm. ■ Horizontal movement was the total movement of the condyle in a forward direction. This move ment was determined by measuring the distance between two parallel vertical lines drawn through the most posterior point and the most anterior point on the pattern. The range for horizontal movement was from 7 to 20.5 mm. with a mean of 12.4 mm. ■ Vertical movement was the total movement of
the condyle in a downward direction. This move ment was measured between parallel lines drawn horizontally through the most superior point and the most inferior point on the pattern. Vertical movement ranged from 5 to 9.5 mm. with a mean of 7.1 mm. ■ Condyle-eminence distance was the distance be tween the nearest point on the pattern to the point representing the eminence. The range for this dis tance was 1.0 to 5.0 mm. with a mean of 2.8 mm. ■ Condyle-fossa distance was the distance between the nearest point on the pattern to the point repre senting the depth of the fossa. The range for this distance was 1.0 to 8.0 mm. with a mean of 3.7 mm. H O R IZO N TAL
■ Fossa-eminence distance was the depth of the fossa or the height of the eminence, the distance between two parallel lines drawn horizontally through the points representing these two struc tures. The range of this depth was 3.0 to 10.0 mm. with a mean of 6.3 mm. ■ Angle of pattern of movement downward and forward was determined by drawing a straight line through the most posterior-superior point on the pattern to the most anterior-inferior point on the pattern nearest the point representing the image of the articular eminence. The angle this line made as it intersected a horizontal line through the point representing the image of the depth of the fossa was determined as the angle of pattern of move ment. Although this criterion for selecting the an terior point of the pattern necessitated omitting part of the anterior pattern in many instances, it seemed that this angle would be most representa tive of the predominant downward and forward movement. This angle ranged from 15 degrees to 48 degrees and had a mean of 31.5 degrees for this group of 20 joints. ■ Angle of eminence to fossa was made by a line drawn between the point representing the articu lar eminence and the depth of fossa as it inter sected the same horizontal line mentioned in the previous angle determination. This angle had a range of 14 degrees to 39 degrees and a mean an gle of 28.6 degrees. ■ Relation of condylar movement to eminence was the relationship between the extent of ante rior condylar movement and articular eminence
( rnm)
H O R IZ O N T A L
(m m )
Fig. 7 ■ Representative samples of plotted graphs show up ward turn beyond eminentia.
and was calculated by noting the position of the most anterior point on the pattern and a line drawn perpendicular to the point representing the image of the height of the eminence. In this relationship, the joints were placed in one of two classes: Class A joints were those that showed a pattern of move ment that moved anterior to the height of the emi nence; Class B joints were those whose patterns stopped posterior or reached the image of the point representing the height of the eminence. Seventy percent of the joints were classified in Class A, and the remaining 30 percent were des ignated as Class B. The incisal-to-incisal maximum opening mea sured before filming the subject was also recorded. This measurement of maximum incisal opening had a range of 33 to 54 mm. with a mean of 42.1 mm. Standard deviation was 7.8. This measure ment was recorded primarily for the determina tion of the condylar movement to incisal opening ratio. Since the ratio of condylar movement to in cisal opening has been recorded in other studies,12 it was thought that the determination of this ratio in the present study would be interesting. This ra tio Was determined by dividing the maximum in cisal opening by the total condylar movement. The range in this ratio was from 1.9:1.0 to 4.8:1.0 with a mean ratio of 3.0:1.0. The frames measured as involved in the open ing and closing movements were recorded. The frame consumption ranged from 10 to 28 with a
McLeran—Montgom ery—Hale: CINEFLUOROGRAPHIC ANALYSIS OF TMJ ■ 1399
Table ■ Sum m ary o f data obtained fro m graphs. Measurement
Range
Mean
Total condylar movement 10.0-20.0 mm. 14.3 mm. Horizontal movement 7.0-20.5 mm. 12.4 mm. Vertical movement 5.0* 9.5 mm. 7.1 mm. Condyle eminence 1.0- 5.0 mm. 2.8 mm. Condyle fossa 1.0- 8.0 mm. 3.7 mm. 3.0-10.0 mm Fossa eminence 6.3 mm. Angle of movement 15°-48° 31.5® Angle o f eminence to fossa 14°-39° 28.6° Maximum incisal opening 33.0-54.0 mm. 42.1 mm. Totol movement to incisal 1.9-1 to 4.8-1 3-1 opening ration Frames in movement 10-28 17.1 Rotation o f condylar movement fo eminence Class A (beyond eminence)...........14 Class B (stops at or posterior to eminence)...........6
SD* 3.2 3.7 1.3 1.1 1.7 1.7 (not determined) (not determined) 7.8 (not determined! (not determined!
*SD = Stondard deviation.
mean frame consumption of 17. Data from this measurement yielded the most bilateral symmetry from subject to subject. A summary of the pertinent data calculated from the main graph measurements is presented in the Table. These measurements are valid for this particular method only. They are not intended as absolute measurements. They will be useful for other investigators in comparison studies that use film obtained from these same angulations and technics.
Discussion
It appears from the results of the study that the pattern of movement of each joint during the open ing and closing movements may vary enough to make it difficult to classify or categorize the nor mally functioning temporomandibular joints. There was a wide variance in individual patterns as shown on the graphs, which would have been difficult to surmise by only observing the projected films as several authors7’ 12*13 have done in their reports. The pattern of movement of the joints was down ward and forward and generally described a curved line with the concavity in a superior direction toward the eminentia. If the path continued be yond the eminentia, it generally took an upward turn as it proceeded forward. This upward turn was seen in joints 166 right, 107 right, 107 left, 125 right, and 125 left, whose patterns are shown in Figure 7. Although others7 have noted a slight horizontal plateau between the end of the hinge axis and the start of the downward and forward glide of the condyle, this feature was not consis tently noted in this study. Consistent with other studies,7 however, an uneven and an irregular path of movement was noted. 1400 ■ JADA, Vol. 75, Dec. 1967
When the points of each successive frame were plotted and connected, the result was a zigzag line in most of the graphs. This zigzag pattern may be partially a result of the inherent error in reading and plotting. There may also be other factors that are important. There is vital importance in the in teraction of the muscles making up the muscular complex that is responsible for the opening and closing movements. Therefore, the zigzag motion might be a result of the interaction of several mus cles as their contraction starts, stops, increases, or diminishes. It is possible that these movements are exaggerated in abnormal joint analysis. The degree of this zigzag characteristic varied for each joint in one subject as well as for the same joint in all subjects. The pronounced degree of irregularity in the pattern of 115 left and the almost smooth pattern in 115 right, which are right and left pat terns of the same subject, are shown in Figure 5 . Many of the patterns of the joints in this study do not support Craddock’s conclusion that “Condy lar movements within the functional range are normally congruent with the fossa outline and maintain a constant separation of about 2 mm. on the articular surface of the glenoid fossa.”13 If indi vidual frames were taken at occlusion, rest, and maximum opening, however, in some static radi ographic studies, 2»7*13-18 this false conclusion could be made. It would appear that any conclu sion that a “Lack of congruency of movement es tablishes prima facie evidence of atypical func tion”13 cannot be supported. Many investigators question whether in the nor mally functioning temporomandibularjoint,thecondylar head moves anterior to the crest of the articu lar eminence in the opening movement.3»6»13*14»17 Some define this as a hypermobile joint. Other investigators think that the normal opening range of the condyle allows it to move anterior to the eminence.2»12*18*19 Results of this study tend to sup port the conclusion that the condyle may normally move anterior to the crest of the eminence since it occurred in 70 percent of the joints that were graphed (Fig. 5, 8). Some investigators12 have concluded that in cisal openings of as much as or less than 35 mm. were never accompanied by excursion of the con dyle beyond the crest of the eminence. In this study, however, in the subjects with 35 mm. or less of incisal opening, 30 percent of these patterns did exceed the point representing the height of the eminence. The ratio of total condylar movement to incisal opening in this study was found to have a mean of 3:1, which compares with other studies with
th e ranges o f as m uch as 6:1. T hese m easurem ents have lim ited value, an d these statistical sum m a ries should not be accepted o r used as absolute m easurem ents. They a re valid only for use in com parison studies th a t use the sam e angulations and technics prim arily because o f a distortion o f anat om y and m ovem ent caused by the angulation and the tw o-dim ensional ch aracter o f the picture.
ifications and im provem ents will m ake it m ore valuable in future studies.
The authors thank Donald S. Dana and Ronald H. Wilkison for their participation in the original research. Doctors McLeran, Montgomery, and Hale are at the Uni versity of Iowa, Iowa City, where Doctors McLeran and Mont gomery are assistant professors and Doctor Hale is a profes sor and head of the department of oral surgery.
Conclusions T he devised m ethod fo r th e use of indirect cinefluorography fo r the investigation o f the tem poro m andibular jo in t appears to offer a m ethod for th e analysis o f the functioning m ovem ents o f the joint. A ttem pts to describe the patterns o f m ovem ent in specific categories o r classes were not successful in this study prim arily because o f the extensive variations in the individual patterns. T his v aria tion existed from subject to subject and from jo in t to joint. A zigzag m ovem ent o f the image o f the condyle was consistently observed. T h e theory th at this pattern m ay be a result o f the individual actions o f the different m uscles controlling the excursion o f the jo in t was suggested. T he p attern o f the condyle did m ove in a dow n w ard and forw ard direction w ith the concavity upw ard during th e opening m ovem ent. W hether this variable m ovem ent p attern w ith the concavity upw ard is enough variation in pathologic joints to m ake them distinctive from norm al jo in ts is not known. In this study, th e condyle did not appear to necessarily assum e a p a th congruent w ith the fossa outline in the articular surface o f the glenoid fossa. If the group from w hich the sam ple for this study was taken can be accepted as norm al, it would appear th a t the norm al physiologic range o f the tem porom andibular jo in t does allow for the m ovem ent o f th e condylar h ead anterior to the eminence. Excursion o f th e condyle beyond the crest o f the em inence was observed in 30 percent o f the subjects w ith as m uch as o r less than 35 mm. o f incisal-to-incisal opening. It w ould ap p ear th at indirect cinefluorography is an excellent and heretofore unequaled technic for th e study o f the tem porom andibular joint. M od
1. Henny, F. A. The temporomandibular joint. In Kruger, G. 0. (ed.). Textbook of oral surgery. St. Louis, C. V. Mosby Co., 1959, p. 356-372. 2. Ricketts, R. M. Laminagraphy in the diagnosis of temporomandibular jo in t disorders. JADA 46:620 June, 1953 3. Updegrave, W. J. Evaluation of temporomandibular jo in t roentgenography. JADA 46:408 April, 1953. 4. Berry, H. M., Jr., and Hofmann, F. A. Preliminary work on cinefluorography with image intensification, in the study of the temporomandibular joint. Oral Surg 10:63 Jan., 1957. 5. Lindblom, Gosta. Anatomy and function of the tem poromandibular joint. Acta Odont Scand (suppl. 28) 17:7, 1960. 6. Lindblom, Gosta. A cineradiographic study of the tem poromandibular joint. Acta Odont Scand 15:141 May, 1957. 7. Berry, H. M., and Hofmann, F. A. Cineradiographic observations of temporomandibular jo in t function. J Prosth Dent 9:21 Jan.-Feb., 1959. 8. Berry, H. M., and Hofmann, F. A. Cinefluorography with image intensification for observing temporomandibular jo in t movements. JADA 53:517 Nov., 1956. 9. Quartararo, I. N., and Zambito, R. F. A preliminary report on the investigation of the possible use of cinefluoro graphic techniques for the study of the temporomandibular joint. New York J Dent 10:215 April, 1952. 10. Higley, L. B. A head positioner for scientific radiographic and photographic purposes. Orthodont Oral Surg Int J 22:699, 1936. 11. Zech, J. M. Comparison and analysis of three tech niques of taking roentgenograms of the temporomandibular joint. JADA 59:725 Oct., 1959. 12. Markowitz, H. A., and Gerry, R. G. Temporomandib ular jo int disease. Oral Surg 2:1309 Oct., 1949. 13. Craddock, F. W. Radiography of the temporomandib ular joint. J Dent Res 32:302 June, 1953. 14. Blackman, Sydney. Serial arthro-radiography for the examination of the temporomandibular joints. Dent Pract (Bristol) 8:227 April, 1957. 15. Donovan, R. W. Method of temporomandibular joint roentgenography for serial and m ultiple records. JADA 49: 401 Oct., 1954. 16. Lawther, W. L. Roentgenograph ic study of the tem poromandibular joint, using a special head positioner. Angle Orthodont 26:22 Jan., 1956. 17. Shore, N. A. Interpretation of the temporomandibu lar jo in t roentgenograms. Oral Surg 13:341 March, 1960. 18. White, T. C.; Campbell, J., and Anderson, H. Layer radiography in temporomandibular jo in t examination. Dent Record 92:49 March, 1957. 19. Bell, W. E. Temporomandibular jo in t disease; a teach ing manual for students and practitioners of dentistry. Dallas, Texas, Egan Co., 1960.
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