CRANIO® The Journal of Craniomandibular & Sleep Practice
ISSN: 0886-9634 (Print) 2151-0903 (Online) Journal homepage: http://www.tandfonline.com/loi/ycra20
Computerized Axiography: Principles and Methods Eva Piehslinger, Aleš G. Čelar, Robert M. Čelar & Rudolph Slavicek To cite this article: Eva Piehslinger, Aleš G. Čelar, Robert M. Čelar & Rudolph Slavicek (1991) Computerized Axiography: Principles and Methods, CRANIO®, 9:4, 344-355, DOI: 10.1080/08869634.1991.11678382 To link to this article: http://dx.doi.org/10.1080/08869634.1991.11678382
Published online: 18 Feb 2016.
Submit your article to this journal
Article views: 1
View related articles
Citing articles: 29 View citing articles
Full Terms & Conditions of access and use can be found at http://www.tandfonline.com/action/journalInformation?journalCode=ycra20 Download by: [Australian Catholic University]
Date: 02 August 2017, At: 08:05
Computerized Axiography: Principles and Methods Eva Piehslinger, M.D., D.D.S., Ales G. Celar, M.D., Robert M. Celar, M.D., Rudolph Slavicek, M.D., D.D.S. Abstract
Downloaded by [Australian Catholic University] at 08:05 02 August 2017
This paper reviews earlier methods for the analysis of mandibular movement and gives a detailed account of state-ofthe-art procedures. Special emphasis is given to computerized axiography and the application of this method to the diagnostics of the temporomandibular joint (TMJ). The article discusses the advantages of computerized axiography over the mechanical device and points out the limitations of the axiographic method. One major advantage of the computerized system is having the enlarged diagram of tracings on the computer screen. This means that small changes such as initial disk displacements can be diagnosed more readily than with the mechanical device.
Dr. Eva Piehslinger received her M.D. degree from the University of Vienna in 1986. During her medical studies she worked for seven years as an assistant at the Anatomical Institute of the University of Vienna. After medical school she received her D.D.S. degree from the Dental School, University of Vienna. Since 1989 she has been in practice at the Dental Clinic in the Department of Removable and Fixed Prosthodontics at the University of Vienna.
Dr. Ales G. Celar studied medicine at the University of Vienna from 1983 to 1989 and received his M.D. degree in 1989. He has been conducting scientific studies at the Dental Clinic of the University of Vienna, Department for Prosthodontics since October 1989. In October 1990 he began in the postgraduate dental education program at the Dental Clinic of the University of Vienna.
344 THE JOURNAL
OF
CRANIOMANDIBULAR
PRACTICE
OCTOBER
1991,
VOL.
9,
NO.
4
0886-9634/91/0904-0344$03.00/0 THE JOURNAL OF CRANIOMANDIBULAR PRACTICE Copyright© 1991 by Williams & Wilkins
Gnathology
Downloaded by [Australian Catholic University] at 08:05 02 August 2017
Historical Review In 1744 Ferrain 1 first described the principles of rotation and translation of the mandibular condyles. His research established that the condyles rotated within the glenoid fossae of the temporal bone with rotational and translational capabilities. He described these movements in all three degrees of freedom as protrusion-retrusion, mediotrusion-medioretrusion, and opening -closing. Langer2 applied moveable needles to the condyles of corpses in 1860. He relocated these needles until they exercised a purely rotational movement on opening and closing. He found that the axis of rotation passed bilaterally through the heads of both condyles. Langer hypothesized that the lower jaw rotates around a momentary axis traveling in space. In 1889 Luce3 tracked mandibular movement photographically by taking still pictures of the travel of extraoral reference points placed on a mandibular bow. Condylar movement was first recorded in 1896 by Ulrich and Walker, 4 who generated graphic curves from a marking stylus fixed to a mandibular face-bow onto plates attached to a cranial bow. Campion5 ( 1902) determined the position of the condyles by palpation and marked its path with dots indicating various condylar positions on the patient's skin. The tracing was transferred to paper and related to an imaginary line from the external auditory meatus to the lower end of the nose. Bennett6 stated in 1908 that whenever the mandible moves during opening, the hinge axis common to both condyles moves as a collinear axis, establishing a true hinge axis. Eitner, in 19097 , 1911, 8 and 1912, 9 discussed the notion of a "hinge axis" from which a pure rotational movement occurred in the lower joint compartment. Eitner assumed that this movement can be carried out by any individual, but that it was different from a normal mouth opening movement. He concluded that raising the bite was a matter of pure hinge movement in the lower part of the joint with the axis passing through both condyles. From 1910 onward Gysi 10 elaborated on the rotational and translatory capabilities of the condyles. He defined the lower compartment of the temporomandibular joint as being the rotational unit and the upper compartment as the translatory component. Gysi used the method employed by Ulrich and Walker4 to program an articulator. In 1912 Andresen 11 used the same method as Eitner
OCTOBER
1991,
VOL.
9,
NO.
4
to locate the hinge axis. He employed an adjustable facebow attached to the mandible with a writing stylus. When the writing stylus did not move during small opening and closing movements, he concluded that he was on the axis. Lehne 12 (1920) followed up the work of Andresen with a modified impression tray designed not to interfere with occlusion while locating the hinge axis. He determined that he was on the hinge axis when no arc was observed during opening and all tracings were on a dot. Andresen and Lehne are credited with the introduction of the kinematic technique for locating the hinge axis. In 1928 the anatomist Sicher 13 demonstrated that pure-hinge movement was possible for the living subject by holding back the lower jaw. He further stated that while a full pure-hinge opening of the mouth was possible in postmortem subjects, living subjects could only achieve two thirds as much opening. In 1934 McCollum 14 introduced the gnathograph as a means of using hinge axis tracings to program an articulator. It is interesting that McCollum, apparently unaware of the European literature, came to the same conclusions as Eitner in his investigation of the existence of a hinge axis of the condyles. From 1935 to 1939 Fischer 15 •16 studied the movement of a point at the midincisal edge of the mandibular centrals and determined that mandibular movement occurred in three dimensions. He further stated that this movement was restricted in space to particular patterns. McCollum 14 stated that the hinge axis of the condyles was stable in space for at least six years in 1938. He showed the influence of Bennett movement on the cusps by mesiodistal movement of the rotating condyle. McCollum used a reference plane (hinge axis to orbital point) to record the sagittal hinge axis tracings on wax-covered glass plates as angles from the reference plane. Posselt 17 showed in 1957 that the mandible is capable of complex movements composed of translation and rotation but that pure rotation around a transverse axis is also possible. He referred to this rotation at the posterior border position as ''terminal hinge movement.'' Page contended that two independent axes occurred in his transographics approach to functional closure of the mandible. This hypothesis was dismissed by the Hinge Axis Committee of the Greater New York Academy of Prosthodontists in 1959. They showed that four hinge axis points, two next to each condyle and two located 12 inches away from each
THE JOURNAL OF CRANIOMANDIBULAR
PRACTICE
345
Downloaded by [Australian Catholic University] at 08:05 02 August 2017
PIEHSLINGER
ET
AL.
COMPUTERIZED AXIOGRAPHY
condyle, were all aligned to the same axis, thus ruling out the existence of two axes. Hielscher imaged condylar movement using x-ray kinematography in 1961. This technique provides information about dynamic aspects and their changing positional relation. Hickey (1963) 18 placed pins in the condyles of two subjects and then photographed the movement exercised by these pins in three dimensions. Puff and Krause 19 ( 1965) quantified the spatial phenomena of functional loading of the joints using sequentially related radiographs of the mandible. Messerman ( 1967) developed the first electronic measuring instrument consisting of six transducers mounted between two external face-bows. It measured six degrees of freedom of jaw motion. Their outputs were fed into a multichannel tape recorder. The playback or duplicating device was named Case Gnathic Replicator, a jaw motion reproducer mechanism. Electrognathography was introduced in 1967 by Bewersdorff2° as a method for recording jaw movements in three dimensions by using three sensors for magnetic induction, each attached to both mandibular and cranial bows. This system offers the advantage of being able to record intraoral functions. Lee first published his studies in 1969. 21 •22 He used dental air turbines located on the hinge axis to engrave condylar movements in plastic blocks. In 1970 Knap et al. created a measuring system using six potentiometers as sensors providing electrical signals from the mandibular incision for computer analysis. This apparatus was located in front of the face. Korber (1971) recorded mandibular kinetics by applying a face-bow system with measuring plates and sensors. Data were recorded by means of an oscilloscope and plotter. Gibbs and Messerman (1971) used a double face-bow system and the Case Gnathic Replicator. It recorded kinetic information of the mandible for playback and computer analysis. In 1975 Jankelson et al. described the mandibular kinesiograph, a far-off joint technique. A permanent magnet was mounted on the mandibular incisors, sensing elements responded to the strength of the magnetic field. Data were stored on tape for later replay or computer analysis. Guichet23 elaborated extensively on pantographing, the programming of an articulator, and waxing techniques in the 1971, Occlusion Manual of the Denar Corporation. In 1972 Preiskel, 24 doing hinge axis tracings, described the "Fischer angle" as the angle between the
346 THE
JOURNAL
OF CRANIOMANDIBULAR
PRACTICE
path traveled by the nonworking side condyle during a lateral border movement and the path along which it travels when a symmetrical protrusion is made. Slavicek25 •26 attributes this angle to the fact that in pantographing the recording flag is attached to the mandible many millimeters from the condyle, thereby introducing an uncontrollable artifact. Rosner27 describes this geometric problem as skew and tilt values arising from not being at the proper intercondylar distance. Lundeen and Wirth, 28 testing the reproducibility of Lee's method in 1973, found that variations in unguided recordings occurred on the same patient with different operators. When the operators guided the patient through border movements, they were reproducible. Heners 29 used an amplifying oscilloscope in 1973 to view sagittal border movements, but not lateral motion, in real time. Lauritzen30 illustrated and explained his extensive usage of the hinge axis position in the mountings of casts and fabrication of prostheses in his Atlas of Occlusal Analysis (1974). In 1976 McCoy et al. 31 used the plastic block engraving technique of Lee and their own research to track mandibular movements and then photographed these engravings for transferring these data to a computer. They concluded that the collection and evaluation of such data could clarify questions concerning occlusion, tooth stability, effect on peridontal health and permit correlations with the success of orthodontic measures. Lundeen et al. 32 evaluated mandibular border movements in 1978, assessing the effect of border and Bennett movements on tooth cusp form. They reasoned that the determination of a patient's Bennett movement and the inclination of the nonworking condylar pathway would provide useful diagnostic and treatment information. In England, Winstanley (1977) 33 reported on the use of pantographic hinge axis tracings to program an articulator. He concluded that reasonable accuracy and reproducibility were obtainable by experienced clinicians. Shields et at.34 concluded in 1978 that hinge axis tracings can be an aid in the detection of temporomandibular dysfunction and muscular incoordination as well as in the assessment of severity. In 1979 Stuart35 obtained optimal occlusion with his articulator frictionless condylar recording so that full mandibular movements could be copied. Simonet36 used the Pantographic Reproducibility In-
OCTOBER
1991,
VOL.
9,
NO.
4
COMPUTERIZED
Downloaded by [Australian Catholic University] at 08:05 02 August 2017
PIEHSLINGER ET AL.
dex in 1981 to categorize a baseline of dysfunction within subjects for studying Bennett movement. In 1982 Klett37 used a light beam emitter with photosensor to measure and record three-dimensional mandibular movements where artifacts could be eliminated. Burckhardt described an optoelectronic infrared system to determine hinge axis and centric relation in 1985 (C.R.J .M.-Stereognathograph). It included computerized evaluation and permitted articulator programming. Seebald used this system for simultaneous and undistorted recordings of condylar movements in space in 1986. Recordings made by three simplified condylar movement recorders were assessed by Mauderli and Lundeen 38 to record internal derangements at the hinge axis. Their 1986 report concludes by stating that this diagnostic information could be preserved as a permanent record in the patient's chart. Alsawaf and Missert39 •40 used the computerized axiograph to study the three-dimensional real-time range of motion of the geometrically calculated hinge axis in condylar resected patients. In another study, using healthy subjects with a located hinge axis, they reported the effect of incisal guidance on hinge axis movement. Missert41 .42 showed how computerized axiographic data can be incorporated into the construction of phase one, two, and three treatment devices in conjunction with computerized occlusal schemes, all referenced to the same diagnostic and therapeutic plane. He also reported on the verification of desired hinge axis repositioning accomplished by these devices. Curtise43 •44 in 1989 compared interocclusal records to pantographic tracings. The Vienna Research Group is reporting on using both methods of axiography to standardize the clinical methodology. Asymptomatic supernormals are studied to investigate the various methods used during the instrumental phase of the dental physical and differential diagnosis.
Method A conventional double face-bow system is attached to the patient. The mandibular bow is used for transmitting hinge axis movements of the mandible to the upper face-bow. The mandibular bow can be adjusted in two dimensions so as to localize the hinge axis in the usual manner. The upper face-bow carries sagittally mounted flags that are used in the electronic registration of hinge axis movement. This permits the
OCTOBER
1991,
VOL.
9,
NO.
4
AXIOGRAPHY
recording hinge axis translation within all mandibular kinetics in two dimensions. In the case of asymmetrical movement, there is telescoping deviation of the recording styli. This corresponds to a combination of the geometrical effect of the sagittal flags and the individual lateral shift of the mandible, the so-called Bennett movement. The use of this axiographic method permits the correlation of Bennett movement and translation.
Procedure Instructing the Patient The patient should be informed about the various steps of the procedure and asked to relax. The patient cannot do anything wrong, though individual steps may have to be repeated. The commands have to be practiced before mounting the face-bows.
Preparing the Instrument The face-bows are prepared, and flags and styli must be connected to the interface.
Making a Paraocclusal Clutch The use of a paraocclusal clutch enlarges the diagnostic spectrum (Slavicek 1981). Temporomandibular joint (TMJ) diagnostics is enhanced by the functional and parafunctional dynamics of the masticatory organ. The paraocclusal clutch permits the evaluation of free or guided border movements without the influence of occlusion and the observation hinge axis movement during function (mastication) and parafunction (bruxism). Furthermore, MPI can be done on the patient, avoiding all inaccuracies of making and mounting casts. The yoke of a brass clutch is hand-bent to within 1 to 2 mm of the buccal and labial surfaces of the mandibular teeth in ICP, free from the maxillary antagonists. An autopolymerizing acrylic is placed on the yoke, and an impression is made of these surfaces. Since the material releases considerable heat, it should be taken out of the mouth repeatedly until the initial set is reached. A horizontal wax wafer can be placed intraorally to keep the acrylic off the maxillary teeth. The patient is instructed to bite to ICP with the wax wafer in place. The clutch, loaded with acrylic, is then inserted repeatedly (Figure 1).
THE JOURNAL
OF CRANIOMANDIBULAR
PRACTICE
347
PIEHSLINGER
ET
AL.
COMPUTERIZED
AXIOGRAPHY
Measuring Flag Distance The distance between the lateral edges of the facebow branches is measured in millimeters.
Mounting the Flags Flags are mounted and fixed with screws.
Mounting the Registering Face-Bow
Downloaded by [Australian Catholic University] at 08:05 02 August 2017
Figure I The paraocclusal clutch fixed to the labial and buccal surfaces of the mandibular teeth.
Mounting the Face-Bow The operator stands behind the patient, holding the face-bow with loose clamps in both hands. Silicone putty is placed on the glabella adapter for patient comfort, conformed to this area while keeping the anterior bow perpendicular to the sagittal plane, and set aside awaiting final set (Figure 2). The cranial bow is attached to the patient by placing the side branches tightly to the head in a parallel sagittal position. The screws are fastened. The red ribbon is placed over the parietal area, the branches of the facebow rest 2 em above the patient's ears. Then a rubber band is attached to the face-bow and fixed to the occiput with enough tension to tighten it.
On the lower bow the branches are loose. Zero is established by approaching the zero marks on the facebow. Cyanoacrylate gel is used to glue the functional occlusion clutch to the teeth, and the mandibular bow is clamped to the rod of the clutch. The lateral bows are aligned parallel to the cranial bow. The holes for the styli are placed in a position approximate to each condyle. The branches of the two face-bows have to be parallelized. For this purpose, the branches of the lower face-bow are held tightly against the branches of the upper bow while rotating the bar of the lower bow. The bolt for the clutch clamp is tightened, securing the anterior bar of the mandibular bow (Figure 3).
Introducing the Styli The recording styli are placed in their respective holes, and moved to an area on the recording plate arbitrarily corresponding to the position of the condyles. The clamping portions of the lateral bows are secured (Figure 4).
Figure 2 The frontal aspect of the patient during computerized axiography. The putty material is placed on the glabella and the paraocclusal clutch is fixed buccally on the teeth of the lower jaw.
348
THE
JOURNAL
OF
CRANIOMANDIBULAR
PRACTICE
Figure 3 Branches of the two bows are parallelized by holding the branches of the lower bow against those of the upper one.
OCTOBER
1991.
VOL.
9,
NO.
4
PIEHSLINGER
ET
COMPUTERIZED
AL.
AXIOGRAPHY
Adjusting the Orbital Marker The orbital point is located by light fingertip palpation of the area below the left eye. The rounded end of the supplied ruler is placed at this site and kept parallel to the cranial bow. The adjustable orbital marking pin is lowered to the ruler, slid medially until the tip touches the side of the nose, and secured. The point on the skin directly under the marker is dotted with a pen. A lead pellet will later be placed on the dot to transfer the orbital point to the head film(s).
Downloaded by [Australian Catholic University] at 08:05 02 August 2017
Fixing the Hinge Axis Figure 4 Flags and styli from lateral.
Once located, the hinge axis has to be registered in the recording system. The examinator takes the patient to reference position using unforced chin point guidance. The foot pedal for registration is pressed, and a double beep indicates that the position has been stored.
Real-Time Display The real-time option from the main menu is used to check the range of motion of the patient on the recording area of the plates in X and Z directions. The Y coordinate can be displayed linearly to check the range of lateral movements.
Locating the Hinge Axis A rotational opening movement of at least 10 mm is necessary to locate the hinge axis. The stylus, when not on the hinge axis position, makes an arc that the computer uses to calculate the center of a circle. This center is the hinge axis. When pathological conditions (diskopathies, bony alterations) preclude such movement, i.e., when only translational movement is possible, the computer calculates a geometric hinge axis position. It also determines the direction and distance to the calculated position. On the screen the hinge axis appears as a circle, the stylus position as a cross. By turning the screws of the lower face-bow, the cross can be moved precisely to the hinge axis position. The distance is indicated to an accuracy of one hundredth of a millimeter. When both styli are close to the hinge axis, the screen changes to a close-up view (zooming option). In living systems it is not possible to set the hinge axis to an accuracy of 0.01 mm; it should lie within 0.2 mm. Having found the hinge axis, one should perform another check to ensure reproducibility. This may be done by slight opening/closing in rotation and watching the axis point, which should not move during pure hinging movement.
OCTOBER
1991,
VOL.
9,
NO.
4
Recording the Tracings The classical movements for the orthopedic and standard functional analyses are available from a menu with numbered options. Entering the number automatically transfers the corresponding text from the list to the record of the next recording to be made. 1. 2. 3. 4. 5. 6. 7.
Open/Close Protrusion/Retrusion Mediotrusion, Right-unguided Mediotrusion, Left-unguided Mediotrusion, Right-guided Mediotrusion, Left-guided Electronic mandibular position indicator (EMPI)
The recordings listed above are standard options that are always available. They can be augmented with subsequent unlimited recordings typed into the record. Usually speech, mastication, swallowing, and bruxing recordings are made with a duration of either four and one-half or nine seconds. These recordings may demonstrate functional patterns. The rotational or translatory character of movement in speaking, as well as asymmetries and avoidance patterns, can be observed. The patient initiates the movement after the operator presses the foot switch. The beginning of the recording is signalled by a beep; the end is indicated by a second beep. The recording is immediately displayed on the screen for assessment and can be either saved or deleted. HCI from the protrusive-retrusive movement
THE JOURNAL
OF CRANlOMANDIBULAR
PRACTICE
349
Downloaded by [Australian Catholic University] at 08:05 02 August 2017
PIEHSLINGER
ET
AL.
COMPUTERIZED
and the Bennett angle of mediotrusion can be used for articulator programming. The electronic device allows the superimposition of several curves in different colors. This display is much more detailed and accurate than in mechanical axiography because the lines are much thinner and tracings are magnified on the screen. Superimposing different curves permits the exact verification of the reproducibility of joint movements. The superimposition of border movements and functional movements like mastication or speech can be of great value in the differential diagnosis of avoidance mechanisms (Figure 5). One major advantage of computerized axiography is that it permits the plotting of Bennett movement. The dial gauge of the mechanical device is not easy to work with, especially when the TMJ is unstable (Figure 6). The graph of the axis movement consists of lines recorded in 0.5-second steps during incursive and excursive movement. The tips of both styli are at the end of these lines, and the distance between the lines represents left to right movement coordination. The curve at the top represents the view from above onto the hinge axis in excursion; second curve from the top, shows incursion. The two lower graphs represent the anterior view of the excursive and incursive movement (Figure 7). Joints with early stages of discopathies usually move more slowly than healthy joints or they may be stopped by obstacles. Muscular imbalance can be detected when there are no reproducible superimposed tracings and when speed changes show an undulating pattern. The protrusion/retrusion +Y
I
I
I
I )o
X
~E I
1....-+--+1 ;:
:
:
:
:
:
t~
·~~
AXIOGRAPHY
computerized system can thus be used to document the progress of physical therapy. Color-coded time curves offer additional help. The uppermost line indicates the distance in millimeters covered by the X, Y, and Z coordinates during four and one-half seconds. The distance "s," the linear pathway from reference position, is also projected. The middle diagram shows the Bennett angle and HCI as functions of time. The lowest row represents the velocities of the X, Y, and Z coordinates and the distance "s" in millimeters per second. These curves show the true distance traveled in space and the accelerations in the X, Y, Z, and "s" directions. A vertical line can be moved in intervals of one-tenth seconds, and the coordinates of each point on the curve can be determined. Bringing the curves in relation with the fourth dimension, time, offers important diagnostic information and is more in accordance with a living system (Figure 8). A cursor can be moved on the axiographic tracings displayed on the screen. By using the arrow keys on the keyboard, the cursor can be moved continuously or in one-tenth to nine-tenths second intervals. Hinge axis movement in time and in space can thus be observed, which makes it possible to recognize asymmetries and evaluate the continuity of movement. In combination with the time curves, this provides valuable diagnostic clues. The advantages of the computerized system will be demonstrated on one special case. The analysis of the axiographic tracings on the screen permitted the detection of pathologies that had never been observed in mechanical axiography. Figure 9 shows an opening-closing movement of average quantity and characteristics. There is a clicking phenomenon that has never been observed using the mechanical device because of the thickness of the lead of the recording pencil. The protrusive movement does not reveal the clicking phenomenon, but it appears again in the chopping movement of mastication. A phenomenon that appears in the rotational, but not in the translatory, movement (protrusion) indicates changes in the lower joint space (in this case on the head of the condyle). The magnetic resonance imaging of the temporomandibular joints showed cystic changes on the right condyle.
Electronic Mandibular Position Indicator (EMPI) Figure 5 The superimposition of two protrusive movements shows the good reproducibility in this case.
350 THE
JOURNAL
OF
CRANIOMANDIBULAR
PRACTICE
The EMPI offers the same data as the mechanical position indicator. The EMPI mode contains a numbered listing of standard recordings.
OCTOBER
1991,
VOL.
9,
NO.
4
PIEHSLINGER
ET
COMPUTERIZED
AL.
MEOIDTRUSION RIGHT GUIDED
AXIOGRAPHY
AXIS MOVH1ENT
+Y
-Y
2
-1
10
I
>
~
X
!I
I
7
6
5
4
3
2
1
Downloaded by [Australian Catholic University] at 08:05 02 August 2017
5 6
7 I
R
!I
L
1.0
+Z
INKURSION
recht• HOI BEN
&
1 2 3 4 5 6 7 8 9 10
.86 72.15
62.52 70.35 71.1!1 71.25 72.84
9.47 6.31 5.38 4.13 3.83 70~U 3.31 68.86 2.98 69.83 3.47 67.42 3.99 66.30 4.09
linka
TiOi BEN 19.94 53.30 -49.73 10.20
60.11
26.31
75.33 5.75 75.86 5.50 71.90 5.02 72.73 5.66 70.77 5.15 68.90 5.14 68.-49 4.87 67.14 4.82
Figure 6 Mediotrusion right of a healthy joint with a continuous increase of the Bennett-angle values.
I. 2. 3. 4. 5. 6.
RCP-ICP Resilience Estimated therapeutic position Power bite Ideal vertical position ICP-ICP after opening
An unlimited number of additional recordings can be made. These recordings can also be done at four and one-half or nine-second intervals. The EMPI measures the difference between any two hinge axis coordinate positions. Data are collected only at the initial and final positions of the recording. The values are indicated as delta x (the deviation in the frontal plane), delta y (the deviation in the transverse plane), and delta z (the deviation in the vertical plane). Each value is given for the right and left side: delta H (computer-calculated height of incisal pin po-
OCTOBER
1991,
VOL.
9,
NO.
4
sition on the incisal table), delta L (anterior-posterior distance of incisal pin position on the incisal table), delta W (left-right distance of incisal pin position on the incisal table), GAMMA (rotational angle of hinge axis). The delta data are immediately displayed after the EMPI record is made and can be saved or deleted (Figure 10). RCP-ICP data can be transferred directly from CADIAX to CADIAS. HCI and Bennett movement are transferred. All tracings including EMPI evaluation can be seen on the screen or can be plotted. Furthermore, data for articulator programming and the waxing technique may be printed on a laboratory sheet. The computer calculates HCI from protrusion-retrusion and the Bennett angle from mediotrusion. When the cusp coordinates are fed into the system, the inclination angles of the cusps can be printed on the laboratory sheet.
THE JOURNAL OF CRANIOMANDIBULAR
PRACTICE
351
PIEHSLINGER
ET AL.
COMPUTERIZED
l-~F'EN/CLOSE
AXIOGRAPHY
AXIS MOVEMENT
+Y
-.40
~
-.40
-a
.co
20
-Y
+Y
-Y
J
_:f
4
I
I
2
I>
4
3
5
7
&
B I
9 I
10 I
>
f:.
El
X
+Y
10
X
-Y
time in
~1 fl
BEH
t
I 2
I 4
I J
•••>
time
I
J
4
Downloaded by [Australian Catholic University] at 08:05 02 August 2017
I I
7
+Y
....
I
R
I
L
10
+Z
+Z
'"
I
~
-10
ID
k1i~~ I>
--·-·----- -·---::=·:.:.::-===: - ·------
-
·-- "*§d
Figure 9 Clicking phenomenon during the opening and closing movement.
The computerized axiograph should be considered an integral part of the differential diagnostic and treatment system. The medical approach to computerized axiography is that of an orthopedic examination of the temporomandibular joints.
Conclusion Computerized axiography permits the recording of mandibular movement and offers analytical systems for evaluation. Data of both temporomandibular joints can be compared simultaneously in relation to changes in space and time. A major advantage of the computerized system lies in the enlarged diagram of the tracings on the computer
OCTOBER
1991,
VOL.
9,
NO.
4
screen. Small changes like initial disk displacements cannot be diagnosed with the mechanical device because of the thickness of the recording pencil. By means of different analytical options, various parameters, such as axis movement in space, acceleration, deceleration, HCI, Bennett angle, and rotation of the hinge axis, can be displayed for simultaneous assessment. This can be instrumental in the differential diagnosis of muscular or ligament problems. Reproducibility can be checked by means of standardized examination or superimposition options. This system permits the measurement and qualification of tracings of the hinge axis and helps determine the characteristics of paths. The records can be used directly for articulator programming. The system facilitates orthopedic quantifying diagnostics at a high level of
THE JOURNAL OF CRANIOMANDIBULAR
PRACTICE
353
PIEHSLINGER
hU·
ET
AL.
lU'
dXR• o.o8 dZR- o. i6 dXL• o. i6 dZL• 0.22
dY•
0.03
dH- -LA7 dlf• -o. i& dL• i.i9
SaMa• -o.65 RCP -
Downloaded by [Australian Catholic University] at 08:05 02 August 2017
dXRdZAdXLa
dZL• dY• dHdlfa
ICP
0.00
O.i9 O.OA
O.iB -O.Oi
2.82 -0.02 -2.06
dl• sa•·
t.2A RCP - ICP
dXR- 0.20 dZR- 0.32 dXL• o.!A dZL• o.26 dY= o.oo
dH= -3.27 dill• -0.07
dl•
2.62 sa•· -i.AA
COMPUTERIZED
ni.::SIUENCE
+X+ .,z +w+z
dXR-= 0.26 dZR-= o. i2
dXLa dY..
+·+ I
O.i3
dZL-= o.5A
-0.06
dH= -i.67
+z
dW.. -o. i6
tt•ill1m
dla i.Ai Ga11ma-= -o •73
it•2mm
RESILIENCE
dXR.. dZR• dXLa dZLc dY• dH• dWa dl•
+~+ +z + +z If
tt-t 111m tt•3mm
+~+ +z ++•z
-o. i2 o. i3 o.i6 0.22 -o.o5
LOO -O.Ai -0.7i
Ga11111a•
o•.w
-> pcwerbite dXR= o.os dZRa o.o8
ICP
dXL= -o. i7 dZL• -0.06 dY• o.oo
tt•tmm
dH= -3.25 dlf• 0.47
tt•3mm
dL•
2.29
tt•2m~,
+z
X
x 1
+z
tt•tmm
it•tmm
+z
+z
- - If
t
tt-1111111 tt-3111111
I
ICP -
dXRa dZR• dXL• dZL• dY•
tt-tln:tl
1+ -r-· +·+ J I
~---X
l
M P
+z
---1--- If
Gaua• -L A3
E
AXIOGRAPHY
ICP aTter- opening
-o.Ao -o. i3 o.o6 o.oo
-0.06
dH-= 0.83
dlf• -0.62
dL• -o.7a
Gallmaa o. 36
+·+ +z
x
I
+z
tt·••
)"
Figure 10 Plotting of the electronic mandibular position indicator (EMPI).
accuracy and is helpful in treatment planning and in the evaluation of therapy. The double stylus system ensures the accurate determination of the hinge axis position and also allows an exact evaluation of rotational capacities. Not only border movements but also functional movements can be of diagnostic value. The recordings of mastication
354 THE
JOURNAL
OF CRANIOMANDIBULAR
PRACTICE
and speech, for instance, can reveal avoidance mechanisms and functional asymmetries. Reprint requests to: Eva Piehslinger, M.D., D.D.S. University of Vienna-School of Medicine Universitiitsldinikfor Zahn-Mund und Kieferheilkunde Wien I 090 Wien, Wlihringerstrasse 25a Vienna, Austria
OCTOBER
1991,
VOL.
9,
NO.
4
PIEHSLINGER
ET
COMPUTERIZED
AL.
Downloaded by [Australian Catholic University] at 08:05 02 August 2017
References I. Ferrain M: Sur les movements de Ia machoire inferieure. Hist Lacad Sci 1744; 578-607 2. Langer K: Das Kiefergelenk des Menschen. Sitzungsber Finn Akad Wiss 1860; 30:457-471 3. Luce CE: The movements of the lower jaw. Boston Med Surg J 1889; 121:8-11 4. Ulrich J: The human temporomandibular joint: Kinematics and actions of the masticatory muscles. J Prosthet Dent 1959; 9:399-406; transl. repr. Walker. from Undersodelser over kjaebeleddet hos mennesket. Kjobenhavn, 1896 5. Campion CG: A method of recording graphically the movements of the mandibular condyles in living subjects. Br Dent J 1902; 23:713716 6. Bennett NG: A contribution to the study of the movements of the mandible. Proc R Soc Med 1908; 1:79-95 7. Eitner E: Kiefergelenk und neuer artikulator. Verh V lnt Zahnarztl Kongr BD 1909; 1:162-164 8. Eitner E: Mechanik des Unterkiefers und der zahniirtzlichen prothese. Dtsch Zahnheilk Vortragen 1911; 20:1-44 9. Eitner E: Der anatomische Artikulator Eitner in der Praxis. Schweiz Vischr Zahnheilk 1912; 22:7-30 10. Gysi A: Beitrag zum Articulations Problem. Berlin. Verlag von August Hirschwald, 1980; 13 II. Andresen V: Die Artikulation der kiefergelenke und der zahnreihen. Dtsch Mschr Zahnheilk 1912; 30:895-922 12. Lehne R: Kritischer Beitrag zur Frage des Rotationspunktes der orthalen und propinalen Unterkieferbewegung. Dissertation, 6, Hamburg, 1920 13. Sicher H: Zur mechanik des kiefergelenks. Z Stomal 1928; 27:27-33 14. McCollum BB: Considering the mouth as a functional unit as a basis of a dental diagnosis. JS Calif Dent Assoc 1938; 5:268-276 15. Fischer R: Die Oeffnungsbewegungen des unterkiefers und ihre wiedergabe am Artikulator. Schweiz Mschr Zahnheilk 1935; 45:867898 16. Fischer R: Die zentrale Oeffnungsbewegung. Dtsch Zahniirztl Wschr 1939; 42:154-160 17. Posselt U: Terminal hinge movement of the mandible. J Prosther Dent 1957; 7:787-797 18. Hickey JC, Allison ML. Woelfel JB. et al.: Mandibular movements in three dimensions. J Prosthet Dent 1963; 13:72-92 19. Puff A. Krause G: Rontgenkinematographische untersuchungen am kiefergelenk unter funktioneller belastung. Dtsch Zahniirztl Z 1965; 20:189-196 20. Bewersdorff HJ: Elektrognathographie--elektronische dreidimensionale messung und registrierung von kieferbewegungen. Dtsch Zahn· Mund· Kieferheilkd 1967; 48:44-119 21. Lee RL: Jaw movements engraved in solid plastic for articulator controls. Part I. Recording Apparatus. J Prosthet Dent 1969; 22:209224 22. Lee RL: Jaw movements engraved in solid plastic for articulator controls. Part 11. Transfer apparatus. J Prosthet Dent 1969; 22:513527 23. Guichet N: Procedures for Occlusal Treatment. A Teaching Atlas. Anaheim: Denar Corp. 1969; 61-77 24. Preiskel HW: Lateral translatory movement of the mandible: Critical review of investigations. J Prosthet Dent 1972; 28:46-57 25. Slavicek R: Clinical and instrumental functional analysis for diagnosis and treatment planning. Part 5. Axiography. J Clin Orthod 1988; 22:(10):656-667 26. Slavicek R: Clinical and instrumental functional analysis for diagnosis and treatment planning. Part 7. Computer-aided axiography. J Clin Orthod 1988; 22(12):776-787 27. Rosner D, Goldberg GF: Condylar retruded contact position and intercuspal position correlation in dentulous patients. Appendix. J Prosthet Dent 1986; 56:238-239 28. Lundeen HC. Wirth CG: Condylar movement patterns engraved in plastic blocks. J Prosthet Dent 1973; 30:866-875
OCTOBER
1991,
VOL.
9,
NO.
4
AXIOGRAPHY
29. Heners M: Elektronisches Verfahren zur registrierung von sagittalen grenzbewegungen des unterkiefers. Dtsch Zahniirztl Z 1973; 28, 4, 532-540 30. Lauritzen AG: Atlas of Occlusal Analysis. Colorado Springs: HAH Publications, 1974 31. McCoy RB, Shryock EF, Lundeen HC: A method of transferring mandibular-movement data to computer storage. J Prosthet Dent 1976; 36:510-516 32. Lundeen HC, Shryock EF, Gibbs CH: An evaluation of mandibular border movements: Their character and significance. J Prosthet Dent 1978; 40:442-452 33. Winstanley RB: Observations on the use of the Denar pantograph and articulator. J Prosthet Dent 1977; 38: 660-672 34. Shields JM, Clayton JA. Sindledecker LD: Using pantographic tracings to detect TMJ and muscle dysfunctions. J Prosthet Dent 1978; 39:80-87 35. Stuart CE: Use of the Stuart articulator in obtaining optimal occlusion. Dent Clin North Am 1979; 23(2):259-270 36. Simonet PF, Clayton JA: Influence of TMJ dysfunction of Bennett movement as recorded by a modified pantograph. Part III: Progress report of the clinical study. J Prosthet Dent 1981; 46:652-661 37. Klett R: Elektronisches Registrierverfahren fiir die Kiefergelenksdiagnostik. Dtsch Zahniirztl Z 1982; 37:991-998 38. Mauderli AR. Lundeen HC: Simplified condylar movement recorders for analyzing TMJ derangements. J Craniomandib Prac 1986; 4:207212 39. Alsawaf M, Missert W: Thesis. University of Pittsburgh, Department of Maxillofacial Surgery, Ear and Eye Hospital-Submitted for publication. 1989, J Prosthet Dent 40. Alsawaf M, Missert W: The relationship between condylar guidance and temporomandibular joint clicking. J Prosthet Dent 1989; 61 :349354 41. Missert W: Diagnostic splint therapy. J Clin Ortho 1989; XXIII:I82192 42. Missert W: Overlay splint therapy. J Clin Ortho 1989; XXIII:253-260 43. Curtise DA: A comparison of protrusive interocclusal records to pantographic tracings. J Prosthet Dent 1989; 62:23-27 44. Curtise DA: A comparison of protrusive interocclusal records to pantographic tracings. J Prosthet Dent 1989; 62:154-156
Robert M. Celar, M.D. Dr. Celar received his M.D. degree from the University of Vienna in 1989. In the fall of the same year he started working as a scientific collaborator at the Dental Clinic of the University of Vienna. In October 1990 he started the postgraduate dental education program at the Dental Clinic of the University of Vienna.
Rudolph Slavicek, M.D., D.D.S. Dr. Slavicek received special training in cardiology and pathology at the University of Vienna, Austria, and received his M.D. degree in 1954. He received his D.D.S. degree in 1957 with special studies in restoration and prosthetics. He is currently in private practice in Vienna and is head of the Dental Clinic Department of Removable and Fixed Prosthodontics at the University of Vienna. He is founding president of the European Academy of Craniomandibular Disorders.
THE JOURNAL OF CRANIOMANDIBULAR
PRACTICE
355
ISSN: 0886-9634 (Print) 2151-0903 (Online) Journal homepage: http://www.tandfonline.com/loi/ycra20
Computerized Axiography: Principles and Methods Eva Piehslinger, Aleš G. Čelar, Robert M. Čelar & Rudolph Slavicek To cite this article: Eva Piehslinger, Aleš G. Čelar, Robert M. Čelar & Rudolph Slavicek (1991) Computerized Axiography: Principles and Methods, CRANIO®, 9:4, 344-355, DOI: 10.1080/08869634.1991.11678382 To link to this article: http://dx.doi.org/10.1080/08869634.1991.11678382
Published online: 18 Feb 2016.
Submit your article to this journal
Article views: 1
View related articles
Citing articles: 29 View citing articles
Full Terms & Conditions of access and use can be found at http://www.tandfonline.com/action/journalInformation?journalCode=ycra20 Download by: [Australian Catholic University]
Date: 02 August 2017, At: 08:05
Computerized Axiography: Principles and Methods Eva Piehslinger, M.D., D.D.S., Ales G. Celar, M.D., Robert M. Celar, M.D., Rudolph Slavicek, M.D., D.D.S. Abstract
Downloaded by [Australian Catholic University] at 08:05 02 August 2017
This paper reviews earlier methods for the analysis of mandibular movement and gives a detailed account of state-ofthe-art procedures. Special emphasis is given to computerized axiography and the application of this method to the diagnostics of the temporomandibular joint (TMJ). The article discusses the advantages of computerized axiography over the mechanical device and points out the limitations of the axiographic method. One major advantage of the computerized system is having the enlarged diagram of tracings on the computer screen. This means that small changes such as initial disk displacements can be diagnosed more readily than with the mechanical device.
Dr. Eva Piehslinger received her M.D. degree from the University of Vienna in 1986. During her medical studies she worked for seven years as an assistant at the Anatomical Institute of the University of Vienna. After medical school she received her D.D.S. degree from the Dental School, University of Vienna. Since 1989 she has been in practice at the Dental Clinic in the Department of Removable and Fixed Prosthodontics at the University of Vienna.
Dr. Ales G. Celar studied medicine at the University of Vienna from 1983 to 1989 and received his M.D. degree in 1989. He has been conducting scientific studies at the Dental Clinic of the University of Vienna, Department for Prosthodontics since October 1989. In October 1990 he began in the postgraduate dental education program at the Dental Clinic of the University of Vienna.
344 THE JOURNAL
OF
CRANIOMANDIBULAR
PRACTICE
OCTOBER
1991,
VOL.
9,
NO.
4
0886-9634/91/0904-0344$03.00/0 THE JOURNAL OF CRANIOMANDIBULAR PRACTICE Copyright© 1991 by Williams & Wilkins
Gnathology
Downloaded by [Australian Catholic University] at 08:05 02 August 2017
Historical Review In 1744 Ferrain 1 first described the principles of rotation and translation of the mandibular condyles. His research established that the condyles rotated within the glenoid fossae of the temporal bone with rotational and translational capabilities. He described these movements in all three degrees of freedom as protrusion-retrusion, mediotrusion-medioretrusion, and opening -closing. Langer2 applied moveable needles to the condyles of corpses in 1860. He relocated these needles until they exercised a purely rotational movement on opening and closing. He found that the axis of rotation passed bilaterally through the heads of both condyles. Langer hypothesized that the lower jaw rotates around a momentary axis traveling in space. In 1889 Luce3 tracked mandibular movement photographically by taking still pictures of the travel of extraoral reference points placed on a mandibular bow. Condylar movement was first recorded in 1896 by Ulrich and Walker, 4 who generated graphic curves from a marking stylus fixed to a mandibular face-bow onto plates attached to a cranial bow. Campion5 ( 1902) determined the position of the condyles by palpation and marked its path with dots indicating various condylar positions on the patient's skin. The tracing was transferred to paper and related to an imaginary line from the external auditory meatus to the lower end of the nose. Bennett6 stated in 1908 that whenever the mandible moves during opening, the hinge axis common to both condyles moves as a collinear axis, establishing a true hinge axis. Eitner, in 19097 , 1911, 8 and 1912, 9 discussed the notion of a "hinge axis" from which a pure rotational movement occurred in the lower joint compartment. Eitner assumed that this movement can be carried out by any individual, but that it was different from a normal mouth opening movement. He concluded that raising the bite was a matter of pure hinge movement in the lower part of the joint with the axis passing through both condyles. From 1910 onward Gysi 10 elaborated on the rotational and translatory capabilities of the condyles. He defined the lower compartment of the temporomandibular joint as being the rotational unit and the upper compartment as the translatory component. Gysi used the method employed by Ulrich and Walker4 to program an articulator. In 1912 Andresen 11 used the same method as Eitner
OCTOBER
1991,
VOL.
9,
NO.
4
to locate the hinge axis. He employed an adjustable facebow attached to the mandible with a writing stylus. When the writing stylus did not move during small opening and closing movements, he concluded that he was on the axis. Lehne 12 (1920) followed up the work of Andresen with a modified impression tray designed not to interfere with occlusion while locating the hinge axis. He determined that he was on the hinge axis when no arc was observed during opening and all tracings were on a dot. Andresen and Lehne are credited with the introduction of the kinematic technique for locating the hinge axis. In 1928 the anatomist Sicher 13 demonstrated that pure-hinge movement was possible for the living subject by holding back the lower jaw. He further stated that while a full pure-hinge opening of the mouth was possible in postmortem subjects, living subjects could only achieve two thirds as much opening. In 1934 McCollum 14 introduced the gnathograph as a means of using hinge axis tracings to program an articulator. It is interesting that McCollum, apparently unaware of the European literature, came to the same conclusions as Eitner in his investigation of the existence of a hinge axis of the condyles. From 1935 to 1939 Fischer 15 •16 studied the movement of a point at the midincisal edge of the mandibular centrals and determined that mandibular movement occurred in three dimensions. He further stated that this movement was restricted in space to particular patterns. McCollum 14 stated that the hinge axis of the condyles was stable in space for at least six years in 1938. He showed the influence of Bennett movement on the cusps by mesiodistal movement of the rotating condyle. McCollum used a reference plane (hinge axis to orbital point) to record the sagittal hinge axis tracings on wax-covered glass plates as angles from the reference plane. Posselt 17 showed in 1957 that the mandible is capable of complex movements composed of translation and rotation but that pure rotation around a transverse axis is also possible. He referred to this rotation at the posterior border position as ''terminal hinge movement.'' Page contended that two independent axes occurred in his transographics approach to functional closure of the mandible. This hypothesis was dismissed by the Hinge Axis Committee of the Greater New York Academy of Prosthodontists in 1959. They showed that four hinge axis points, two next to each condyle and two located 12 inches away from each
THE JOURNAL OF CRANIOMANDIBULAR
PRACTICE
345
Downloaded by [Australian Catholic University] at 08:05 02 August 2017
PIEHSLINGER
ET
AL.
COMPUTERIZED AXIOGRAPHY
condyle, were all aligned to the same axis, thus ruling out the existence of two axes. Hielscher imaged condylar movement using x-ray kinematography in 1961. This technique provides information about dynamic aspects and their changing positional relation. Hickey (1963) 18 placed pins in the condyles of two subjects and then photographed the movement exercised by these pins in three dimensions. Puff and Krause 19 ( 1965) quantified the spatial phenomena of functional loading of the joints using sequentially related radiographs of the mandible. Messerman ( 1967) developed the first electronic measuring instrument consisting of six transducers mounted between two external face-bows. It measured six degrees of freedom of jaw motion. Their outputs were fed into a multichannel tape recorder. The playback or duplicating device was named Case Gnathic Replicator, a jaw motion reproducer mechanism. Electrognathography was introduced in 1967 by Bewersdorff2° as a method for recording jaw movements in three dimensions by using three sensors for magnetic induction, each attached to both mandibular and cranial bows. This system offers the advantage of being able to record intraoral functions. Lee first published his studies in 1969. 21 •22 He used dental air turbines located on the hinge axis to engrave condylar movements in plastic blocks. In 1970 Knap et al. created a measuring system using six potentiometers as sensors providing electrical signals from the mandibular incision for computer analysis. This apparatus was located in front of the face. Korber (1971) recorded mandibular kinetics by applying a face-bow system with measuring plates and sensors. Data were recorded by means of an oscilloscope and plotter. Gibbs and Messerman (1971) used a double face-bow system and the Case Gnathic Replicator. It recorded kinetic information of the mandible for playback and computer analysis. In 1975 Jankelson et al. described the mandibular kinesiograph, a far-off joint technique. A permanent magnet was mounted on the mandibular incisors, sensing elements responded to the strength of the magnetic field. Data were stored on tape for later replay or computer analysis. Guichet23 elaborated extensively on pantographing, the programming of an articulator, and waxing techniques in the 1971, Occlusion Manual of the Denar Corporation. In 1972 Preiskel, 24 doing hinge axis tracings, described the "Fischer angle" as the angle between the
346 THE
JOURNAL
OF CRANIOMANDIBULAR
PRACTICE
path traveled by the nonworking side condyle during a lateral border movement and the path along which it travels when a symmetrical protrusion is made. Slavicek25 •26 attributes this angle to the fact that in pantographing the recording flag is attached to the mandible many millimeters from the condyle, thereby introducing an uncontrollable artifact. Rosner27 describes this geometric problem as skew and tilt values arising from not being at the proper intercondylar distance. Lundeen and Wirth, 28 testing the reproducibility of Lee's method in 1973, found that variations in unguided recordings occurred on the same patient with different operators. When the operators guided the patient through border movements, they were reproducible. Heners 29 used an amplifying oscilloscope in 1973 to view sagittal border movements, but not lateral motion, in real time. Lauritzen30 illustrated and explained his extensive usage of the hinge axis position in the mountings of casts and fabrication of prostheses in his Atlas of Occlusal Analysis (1974). In 1976 McCoy et al. 31 used the plastic block engraving technique of Lee and their own research to track mandibular movements and then photographed these engravings for transferring these data to a computer. They concluded that the collection and evaluation of such data could clarify questions concerning occlusion, tooth stability, effect on peridontal health and permit correlations with the success of orthodontic measures. Lundeen et al. 32 evaluated mandibular border movements in 1978, assessing the effect of border and Bennett movements on tooth cusp form. They reasoned that the determination of a patient's Bennett movement and the inclination of the nonworking condylar pathway would provide useful diagnostic and treatment information. In England, Winstanley (1977) 33 reported on the use of pantographic hinge axis tracings to program an articulator. He concluded that reasonable accuracy and reproducibility were obtainable by experienced clinicians. Shields et at.34 concluded in 1978 that hinge axis tracings can be an aid in the detection of temporomandibular dysfunction and muscular incoordination as well as in the assessment of severity. In 1979 Stuart35 obtained optimal occlusion with his articulator frictionless condylar recording so that full mandibular movements could be copied. Simonet36 used the Pantographic Reproducibility In-
OCTOBER
1991,
VOL.
9,
NO.
4
COMPUTERIZED
Downloaded by [Australian Catholic University] at 08:05 02 August 2017
PIEHSLINGER ET AL.
dex in 1981 to categorize a baseline of dysfunction within subjects for studying Bennett movement. In 1982 Klett37 used a light beam emitter with photosensor to measure and record three-dimensional mandibular movements where artifacts could be eliminated. Burckhardt described an optoelectronic infrared system to determine hinge axis and centric relation in 1985 (C.R.J .M.-Stereognathograph). It included computerized evaluation and permitted articulator programming. Seebald used this system for simultaneous and undistorted recordings of condylar movements in space in 1986. Recordings made by three simplified condylar movement recorders were assessed by Mauderli and Lundeen 38 to record internal derangements at the hinge axis. Their 1986 report concludes by stating that this diagnostic information could be preserved as a permanent record in the patient's chart. Alsawaf and Missert39 •40 used the computerized axiograph to study the three-dimensional real-time range of motion of the geometrically calculated hinge axis in condylar resected patients. In another study, using healthy subjects with a located hinge axis, they reported the effect of incisal guidance on hinge axis movement. Missert41 .42 showed how computerized axiographic data can be incorporated into the construction of phase one, two, and three treatment devices in conjunction with computerized occlusal schemes, all referenced to the same diagnostic and therapeutic plane. He also reported on the verification of desired hinge axis repositioning accomplished by these devices. Curtise43 •44 in 1989 compared interocclusal records to pantographic tracings. The Vienna Research Group is reporting on using both methods of axiography to standardize the clinical methodology. Asymptomatic supernormals are studied to investigate the various methods used during the instrumental phase of the dental physical and differential diagnosis.
Method A conventional double face-bow system is attached to the patient. The mandibular bow is used for transmitting hinge axis movements of the mandible to the upper face-bow. The mandibular bow can be adjusted in two dimensions so as to localize the hinge axis in the usual manner. The upper face-bow carries sagittally mounted flags that are used in the electronic registration of hinge axis movement. This permits the
OCTOBER
1991,
VOL.
9,
NO.
4
AXIOGRAPHY
recording hinge axis translation within all mandibular kinetics in two dimensions. In the case of asymmetrical movement, there is telescoping deviation of the recording styli. This corresponds to a combination of the geometrical effect of the sagittal flags and the individual lateral shift of the mandible, the so-called Bennett movement. The use of this axiographic method permits the correlation of Bennett movement and translation.
Procedure Instructing the Patient The patient should be informed about the various steps of the procedure and asked to relax. The patient cannot do anything wrong, though individual steps may have to be repeated. The commands have to be practiced before mounting the face-bows.
Preparing the Instrument The face-bows are prepared, and flags and styli must be connected to the interface.
Making a Paraocclusal Clutch The use of a paraocclusal clutch enlarges the diagnostic spectrum (Slavicek 1981). Temporomandibular joint (TMJ) diagnostics is enhanced by the functional and parafunctional dynamics of the masticatory organ. The paraocclusal clutch permits the evaluation of free or guided border movements without the influence of occlusion and the observation hinge axis movement during function (mastication) and parafunction (bruxism). Furthermore, MPI can be done on the patient, avoiding all inaccuracies of making and mounting casts. The yoke of a brass clutch is hand-bent to within 1 to 2 mm of the buccal and labial surfaces of the mandibular teeth in ICP, free from the maxillary antagonists. An autopolymerizing acrylic is placed on the yoke, and an impression is made of these surfaces. Since the material releases considerable heat, it should be taken out of the mouth repeatedly until the initial set is reached. A horizontal wax wafer can be placed intraorally to keep the acrylic off the maxillary teeth. The patient is instructed to bite to ICP with the wax wafer in place. The clutch, loaded with acrylic, is then inserted repeatedly (Figure 1).
THE JOURNAL
OF CRANIOMANDIBULAR
PRACTICE
347
PIEHSLINGER
ET
AL.
COMPUTERIZED
AXIOGRAPHY
Measuring Flag Distance The distance between the lateral edges of the facebow branches is measured in millimeters.
Mounting the Flags Flags are mounted and fixed with screws.
Mounting the Registering Face-Bow
Downloaded by [Australian Catholic University] at 08:05 02 August 2017
Figure I The paraocclusal clutch fixed to the labial and buccal surfaces of the mandibular teeth.
Mounting the Face-Bow The operator stands behind the patient, holding the face-bow with loose clamps in both hands. Silicone putty is placed on the glabella adapter for patient comfort, conformed to this area while keeping the anterior bow perpendicular to the sagittal plane, and set aside awaiting final set (Figure 2). The cranial bow is attached to the patient by placing the side branches tightly to the head in a parallel sagittal position. The screws are fastened. The red ribbon is placed over the parietal area, the branches of the facebow rest 2 em above the patient's ears. Then a rubber band is attached to the face-bow and fixed to the occiput with enough tension to tighten it.
On the lower bow the branches are loose. Zero is established by approaching the zero marks on the facebow. Cyanoacrylate gel is used to glue the functional occlusion clutch to the teeth, and the mandibular bow is clamped to the rod of the clutch. The lateral bows are aligned parallel to the cranial bow. The holes for the styli are placed in a position approximate to each condyle. The branches of the two face-bows have to be parallelized. For this purpose, the branches of the lower face-bow are held tightly against the branches of the upper bow while rotating the bar of the lower bow. The bolt for the clutch clamp is tightened, securing the anterior bar of the mandibular bow (Figure 3).
Introducing the Styli The recording styli are placed in their respective holes, and moved to an area on the recording plate arbitrarily corresponding to the position of the condyles. The clamping portions of the lateral bows are secured (Figure 4).
Figure 2 The frontal aspect of the patient during computerized axiography. The putty material is placed on the glabella and the paraocclusal clutch is fixed buccally on the teeth of the lower jaw.
348
THE
JOURNAL
OF
CRANIOMANDIBULAR
PRACTICE
Figure 3 Branches of the two bows are parallelized by holding the branches of the lower bow against those of the upper one.
OCTOBER
1991.
VOL.
9,
NO.
4
PIEHSLINGER
ET
COMPUTERIZED
AL.
AXIOGRAPHY
Adjusting the Orbital Marker The orbital point is located by light fingertip palpation of the area below the left eye. The rounded end of the supplied ruler is placed at this site and kept parallel to the cranial bow. The adjustable orbital marking pin is lowered to the ruler, slid medially until the tip touches the side of the nose, and secured. The point on the skin directly under the marker is dotted with a pen. A lead pellet will later be placed on the dot to transfer the orbital point to the head film(s).
Downloaded by [Australian Catholic University] at 08:05 02 August 2017
Fixing the Hinge Axis Figure 4 Flags and styli from lateral.
Once located, the hinge axis has to be registered in the recording system. The examinator takes the patient to reference position using unforced chin point guidance. The foot pedal for registration is pressed, and a double beep indicates that the position has been stored.
Real-Time Display The real-time option from the main menu is used to check the range of motion of the patient on the recording area of the plates in X and Z directions. The Y coordinate can be displayed linearly to check the range of lateral movements.
Locating the Hinge Axis A rotational opening movement of at least 10 mm is necessary to locate the hinge axis. The stylus, when not on the hinge axis position, makes an arc that the computer uses to calculate the center of a circle. This center is the hinge axis. When pathological conditions (diskopathies, bony alterations) preclude such movement, i.e., when only translational movement is possible, the computer calculates a geometric hinge axis position. It also determines the direction and distance to the calculated position. On the screen the hinge axis appears as a circle, the stylus position as a cross. By turning the screws of the lower face-bow, the cross can be moved precisely to the hinge axis position. The distance is indicated to an accuracy of one hundredth of a millimeter. When both styli are close to the hinge axis, the screen changes to a close-up view (zooming option). In living systems it is not possible to set the hinge axis to an accuracy of 0.01 mm; it should lie within 0.2 mm. Having found the hinge axis, one should perform another check to ensure reproducibility. This may be done by slight opening/closing in rotation and watching the axis point, which should not move during pure hinging movement.
OCTOBER
1991,
VOL.
9,
NO.
4
Recording the Tracings The classical movements for the orthopedic and standard functional analyses are available from a menu with numbered options. Entering the number automatically transfers the corresponding text from the list to the record of the next recording to be made. 1. 2. 3. 4. 5. 6. 7.
Open/Close Protrusion/Retrusion Mediotrusion, Right-unguided Mediotrusion, Left-unguided Mediotrusion, Right-guided Mediotrusion, Left-guided Electronic mandibular position indicator (EMPI)
The recordings listed above are standard options that are always available. They can be augmented with subsequent unlimited recordings typed into the record. Usually speech, mastication, swallowing, and bruxing recordings are made with a duration of either four and one-half or nine seconds. These recordings may demonstrate functional patterns. The rotational or translatory character of movement in speaking, as well as asymmetries and avoidance patterns, can be observed. The patient initiates the movement after the operator presses the foot switch. The beginning of the recording is signalled by a beep; the end is indicated by a second beep. The recording is immediately displayed on the screen for assessment and can be either saved or deleted. HCI from the protrusive-retrusive movement
THE JOURNAL
OF CRANlOMANDIBULAR
PRACTICE
349
Downloaded by [Australian Catholic University] at 08:05 02 August 2017
PIEHSLINGER
ET
AL.
COMPUTERIZED
and the Bennett angle of mediotrusion can be used for articulator programming. The electronic device allows the superimposition of several curves in different colors. This display is much more detailed and accurate than in mechanical axiography because the lines are much thinner and tracings are magnified on the screen. Superimposing different curves permits the exact verification of the reproducibility of joint movements. The superimposition of border movements and functional movements like mastication or speech can be of great value in the differential diagnosis of avoidance mechanisms (Figure 5). One major advantage of computerized axiography is that it permits the plotting of Bennett movement. The dial gauge of the mechanical device is not easy to work with, especially when the TMJ is unstable (Figure 6). The graph of the axis movement consists of lines recorded in 0.5-second steps during incursive and excursive movement. The tips of both styli are at the end of these lines, and the distance between the lines represents left to right movement coordination. The curve at the top represents the view from above onto the hinge axis in excursion; second curve from the top, shows incursion. The two lower graphs represent the anterior view of the excursive and incursive movement (Figure 7). Joints with early stages of discopathies usually move more slowly than healthy joints or they may be stopped by obstacles. Muscular imbalance can be detected when there are no reproducible superimposed tracings and when speed changes show an undulating pattern. The protrusion/retrusion +Y
I
I
I
I )o
X
~E I
1....-+--+1 ;:
:
:
:
:
:
t~
·~~
AXIOGRAPHY
computerized system can thus be used to document the progress of physical therapy. Color-coded time curves offer additional help. The uppermost line indicates the distance in millimeters covered by the X, Y, and Z coordinates during four and one-half seconds. The distance "s," the linear pathway from reference position, is also projected. The middle diagram shows the Bennett angle and HCI as functions of time. The lowest row represents the velocities of the X, Y, and Z coordinates and the distance "s" in millimeters per second. These curves show the true distance traveled in space and the accelerations in the X, Y, Z, and "s" directions. A vertical line can be moved in intervals of one-tenth seconds, and the coordinates of each point on the curve can be determined. Bringing the curves in relation with the fourth dimension, time, offers important diagnostic information and is more in accordance with a living system (Figure 8). A cursor can be moved on the axiographic tracings displayed on the screen. By using the arrow keys on the keyboard, the cursor can be moved continuously or in one-tenth to nine-tenths second intervals. Hinge axis movement in time and in space can thus be observed, which makes it possible to recognize asymmetries and evaluate the continuity of movement. In combination with the time curves, this provides valuable diagnostic clues. The advantages of the computerized system will be demonstrated on one special case. The analysis of the axiographic tracings on the screen permitted the detection of pathologies that had never been observed in mechanical axiography. Figure 9 shows an opening-closing movement of average quantity and characteristics. There is a clicking phenomenon that has never been observed using the mechanical device because of the thickness of the lead of the recording pencil. The protrusive movement does not reveal the clicking phenomenon, but it appears again in the chopping movement of mastication. A phenomenon that appears in the rotational, but not in the translatory, movement (protrusion) indicates changes in the lower joint space (in this case on the head of the condyle). The magnetic resonance imaging of the temporomandibular joints showed cystic changes on the right condyle.
Electronic Mandibular Position Indicator (EMPI) Figure 5 The superimposition of two protrusive movements shows the good reproducibility in this case.
350 THE
JOURNAL
OF
CRANIOMANDIBULAR
PRACTICE
The EMPI offers the same data as the mechanical position indicator. The EMPI mode contains a numbered listing of standard recordings.
OCTOBER
1991,
VOL.
9,
NO.
4
PIEHSLINGER
ET
COMPUTERIZED
AL.
MEOIDTRUSION RIGHT GUIDED
AXIOGRAPHY
AXIS MOVH1ENT
+Y
-Y
2
-1
10
I
>
~
X
!I
I
7
6
5
4
3
2
1
Downloaded by [Australian Catholic University] at 08:05 02 August 2017
5 6
7 I
R
!I
L
1.0
+Z
INKURSION
recht• HOI BEN
&
1 2 3 4 5 6 7 8 9 10
.86 72.15
62.52 70.35 71.1!1 71.25 72.84
9.47 6.31 5.38 4.13 3.83 70~U 3.31 68.86 2.98 69.83 3.47 67.42 3.99 66.30 4.09
linka
TiOi BEN 19.94 53.30 -49.73 10.20
60.11
26.31
75.33 5.75 75.86 5.50 71.90 5.02 72.73 5.66 70.77 5.15 68.90 5.14 68.-49 4.87 67.14 4.82
Figure 6 Mediotrusion right of a healthy joint with a continuous increase of the Bennett-angle values.
I. 2. 3. 4. 5. 6.
RCP-ICP Resilience Estimated therapeutic position Power bite Ideal vertical position ICP-ICP after opening
An unlimited number of additional recordings can be made. These recordings can also be done at four and one-half or nine-second intervals. The EMPI measures the difference between any two hinge axis coordinate positions. Data are collected only at the initial and final positions of the recording. The values are indicated as delta x (the deviation in the frontal plane), delta y (the deviation in the transverse plane), and delta z (the deviation in the vertical plane). Each value is given for the right and left side: delta H (computer-calculated height of incisal pin po-
OCTOBER
1991,
VOL.
9,
NO.
4
sition on the incisal table), delta L (anterior-posterior distance of incisal pin position on the incisal table), delta W (left-right distance of incisal pin position on the incisal table), GAMMA (rotational angle of hinge axis). The delta data are immediately displayed after the EMPI record is made and can be saved or deleted (Figure 10). RCP-ICP data can be transferred directly from CADIAX to CADIAS. HCI and Bennett movement are transferred. All tracings including EMPI evaluation can be seen on the screen or can be plotted. Furthermore, data for articulator programming and the waxing technique may be printed on a laboratory sheet. The computer calculates HCI from protrusion-retrusion and the Bennett angle from mediotrusion. When the cusp coordinates are fed into the system, the inclination angles of the cusps can be printed on the laboratory sheet.
THE JOURNAL OF CRANIOMANDIBULAR
PRACTICE
351
PIEHSLINGER
ET AL.
COMPUTERIZED
l-~F'EN/CLOSE
AXIOGRAPHY
AXIS MOVEMENT
+Y
-.40
~
-.40
-a
.co
20
-Y
+Y
-Y
J
_:f
4
I
I
2
I>
4
3
5
7
&
B I
9 I
10 I
>
f:.
El
X
+Y
10
X
-Y
time in
~1 fl
BEH
t
I 2
I 4
I J
•••>
time
I
J
4
Downloaded by [Australian Catholic University] at 08:05 02 August 2017
I I
7
+Y
....
I
R
I
L
10
+Z
+Z
'"
I
~
-10
ID
k1i~~ I>
--·-·----- -·---::=·:.:.::-===: - ·------
-
·-- "*§d
Figure 9 Clicking phenomenon during the opening and closing movement.
The computerized axiograph should be considered an integral part of the differential diagnostic and treatment system. The medical approach to computerized axiography is that of an orthopedic examination of the temporomandibular joints.
Conclusion Computerized axiography permits the recording of mandibular movement and offers analytical systems for evaluation. Data of both temporomandibular joints can be compared simultaneously in relation to changes in space and time. A major advantage of the computerized system lies in the enlarged diagram of the tracings on the computer
OCTOBER
1991,
VOL.
9,
NO.
4
screen. Small changes like initial disk displacements cannot be diagnosed with the mechanical device because of the thickness of the recording pencil. By means of different analytical options, various parameters, such as axis movement in space, acceleration, deceleration, HCI, Bennett angle, and rotation of the hinge axis, can be displayed for simultaneous assessment. This can be instrumental in the differential diagnosis of muscular or ligament problems. Reproducibility can be checked by means of standardized examination or superimposition options. This system permits the measurement and qualification of tracings of the hinge axis and helps determine the characteristics of paths. The records can be used directly for articulator programming. The system facilitates orthopedic quantifying diagnostics at a high level of
THE JOURNAL OF CRANIOMANDIBULAR
PRACTICE
353
PIEHSLINGER
hU·
ET
AL.
lU'
dXR• o.o8 dZR- o. i6 dXL• o. i6 dZL• 0.22
dY•
0.03
dH- -LA7 dlf• -o. i& dL• i.i9
SaMa• -o.65 RCP -
Downloaded by [Australian Catholic University] at 08:05 02 August 2017
dXRdZAdXLa
dZL• dY• dHdlfa
ICP
0.00
O.i9 O.OA
O.iB -O.Oi
2.82 -0.02 -2.06
dl• sa•·
t.2A RCP - ICP
dXR- 0.20 dZR- 0.32 dXL• o.!A dZL• o.26 dY= o.oo
dH= -3.27 dill• -0.07
dl•
2.62 sa•· -i.AA
COMPUTERIZED
ni.::SIUENCE
+X+ .,z +w+z
dXR-= 0.26 dZR-= o. i2
dXLa dY..
+·+ I
O.i3
dZL-= o.5A
-0.06
dH= -i.67
+z
dW.. -o. i6
tt•ill1m
dla i.Ai Ga11ma-= -o •73
it•2mm
RESILIENCE
dXR.. dZR• dXLa dZLc dY• dH• dWa dl•
+~+ +z + +z If
tt-t 111m tt•3mm
+~+ +z ++•z
-o. i2 o. i3 o.i6 0.22 -o.o5
LOO -O.Ai -0.7i
Ga11111a•
o•.w
-> pcwerbite dXR= o.os dZRa o.o8
ICP
dXL= -o. i7 dZL• -0.06 dY• o.oo
tt•tmm
dH= -3.25 dlf• 0.47
tt•3mm
dL•
2.29
tt•2m~,
+z
X
x 1
+z
tt•tmm
it•tmm
+z
+z
- - If
t
tt-1111111 tt-3111111
I
ICP -
dXRa dZR• dXL• dZL• dY•
tt-tln:tl
1+ -r-· +·+ J I
~---X
l
M P
+z
---1--- If
Gaua• -L A3
E
AXIOGRAPHY
ICP aTter- opening
-o.Ao -o. i3 o.o6 o.oo
-0.06
dH-= 0.83
dlf• -0.62
dL• -o.7a
Gallmaa o. 36
+·+ +z
x
I
+z
tt·••
)"
Figure 10 Plotting of the electronic mandibular position indicator (EMPI).
accuracy and is helpful in treatment planning and in the evaluation of therapy. The double stylus system ensures the accurate determination of the hinge axis position and also allows an exact evaluation of rotational capacities. Not only border movements but also functional movements can be of diagnostic value. The recordings of mastication
354 THE
JOURNAL
OF CRANIOMANDIBULAR
PRACTICE
and speech, for instance, can reveal avoidance mechanisms and functional asymmetries. Reprint requests to: Eva Piehslinger, M.D., D.D.S. University of Vienna-School of Medicine Universitiitsldinikfor Zahn-Mund und Kieferheilkunde Wien I 090 Wien, Wlihringerstrasse 25a Vienna, Austria
OCTOBER
1991,
VOL.
9,
NO.
4
PIEHSLINGER
ET
COMPUTERIZED
AL.
Downloaded by [Australian Catholic University] at 08:05 02 August 2017
References I. Ferrain M: Sur les movements de Ia machoire inferieure. Hist Lacad Sci 1744; 578-607 2. Langer K: Das Kiefergelenk des Menschen. Sitzungsber Finn Akad Wiss 1860; 30:457-471 3. Luce CE: The movements of the lower jaw. Boston Med Surg J 1889; 121:8-11 4. Ulrich J: The human temporomandibular joint: Kinematics and actions of the masticatory muscles. J Prosthet Dent 1959; 9:399-406; transl. repr. Walker. from Undersodelser over kjaebeleddet hos mennesket. Kjobenhavn, 1896 5. Campion CG: A method of recording graphically the movements of the mandibular condyles in living subjects. Br Dent J 1902; 23:713716 6. Bennett NG: A contribution to the study of the movements of the mandible. Proc R Soc Med 1908; 1:79-95 7. Eitner E: Kiefergelenk und neuer artikulator. Verh V lnt Zahnarztl Kongr BD 1909; 1:162-164 8. Eitner E: Mechanik des Unterkiefers und der zahniirtzlichen prothese. Dtsch Zahnheilk Vortragen 1911; 20:1-44 9. Eitner E: Der anatomische Artikulator Eitner in der Praxis. Schweiz Vischr Zahnheilk 1912; 22:7-30 10. Gysi A: Beitrag zum Articulations Problem. Berlin. Verlag von August Hirschwald, 1980; 13 II. Andresen V: Die Artikulation der kiefergelenke und der zahnreihen. Dtsch Mschr Zahnheilk 1912; 30:895-922 12. Lehne R: Kritischer Beitrag zur Frage des Rotationspunktes der orthalen und propinalen Unterkieferbewegung. Dissertation, 6, Hamburg, 1920 13. Sicher H: Zur mechanik des kiefergelenks. Z Stomal 1928; 27:27-33 14. McCollum BB: Considering the mouth as a functional unit as a basis of a dental diagnosis. JS Calif Dent Assoc 1938; 5:268-276 15. Fischer R: Die Oeffnungsbewegungen des unterkiefers und ihre wiedergabe am Artikulator. Schweiz Mschr Zahnheilk 1935; 45:867898 16. Fischer R: Die zentrale Oeffnungsbewegung. Dtsch Zahniirztl Wschr 1939; 42:154-160 17. Posselt U: Terminal hinge movement of the mandible. J Prosther Dent 1957; 7:787-797 18. Hickey JC, Allison ML. Woelfel JB. et al.: Mandibular movements in three dimensions. J Prosthet Dent 1963; 13:72-92 19. Puff A. Krause G: Rontgenkinematographische untersuchungen am kiefergelenk unter funktioneller belastung. Dtsch Zahniirztl Z 1965; 20:189-196 20. Bewersdorff HJ: Elektrognathographie--elektronische dreidimensionale messung und registrierung von kieferbewegungen. Dtsch Zahn· Mund· Kieferheilkd 1967; 48:44-119 21. Lee RL: Jaw movements engraved in solid plastic for articulator controls. Part I. Recording Apparatus. J Prosthet Dent 1969; 22:209224 22. Lee RL: Jaw movements engraved in solid plastic for articulator controls. Part 11. Transfer apparatus. J Prosthet Dent 1969; 22:513527 23. Guichet N: Procedures for Occlusal Treatment. A Teaching Atlas. Anaheim: Denar Corp. 1969; 61-77 24. Preiskel HW: Lateral translatory movement of the mandible: Critical review of investigations. J Prosthet Dent 1972; 28:46-57 25. Slavicek R: Clinical and instrumental functional analysis for diagnosis and treatment planning. Part 5. Axiography. J Clin Orthod 1988; 22:(10):656-667 26. Slavicek R: Clinical and instrumental functional analysis for diagnosis and treatment planning. Part 7. Computer-aided axiography. J Clin Orthod 1988; 22(12):776-787 27. Rosner D, Goldberg GF: Condylar retruded contact position and intercuspal position correlation in dentulous patients. Appendix. J Prosthet Dent 1986; 56:238-239 28. Lundeen HC. Wirth CG: Condylar movement patterns engraved in plastic blocks. J Prosthet Dent 1973; 30:866-875
OCTOBER
1991,
VOL.
9,
NO.
4
AXIOGRAPHY
29. Heners M: Elektronisches Verfahren zur registrierung von sagittalen grenzbewegungen des unterkiefers. Dtsch Zahniirztl Z 1973; 28, 4, 532-540 30. Lauritzen AG: Atlas of Occlusal Analysis. Colorado Springs: HAH Publications, 1974 31. McCoy RB, Shryock EF, Lundeen HC: A method of transferring mandibular-movement data to computer storage. J Prosthet Dent 1976; 36:510-516 32. Lundeen HC, Shryock EF, Gibbs CH: An evaluation of mandibular border movements: Their character and significance. J Prosthet Dent 1978; 40:442-452 33. Winstanley RB: Observations on the use of the Denar pantograph and articulator. J Prosthet Dent 1977; 38: 660-672 34. Shields JM, Clayton JA. Sindledecker LD: Using pantographic tracings to detect TMJ and muscle dysfunctions. J Prosthet Dent 1978; 39:80-87 35. Stuart CE: Use of the Stuart articulator in obtaining optimal occlusion. Dent Clin North Am 1979; 23(2):259-270 36. Simonet PF, Clayton JA: Influence of TMJ dysfunction of Bennett movement as recorded by a modified pantograph. Part III: Progress report of the clinical study. J Prosthet Dent 1981; 46:652-661 37. Klett R: Elektronisches Registrierverfahren fiir die Kiefergelenksdiagnostik. Dtsch Zahniirztl Z 1982; 37:991-998 38. Mauderli AR. Lundeen HC: Simplified condylar movement recorders for analyzing TMJ derangements. J Craniomandib Prac 1986; 4:207212 39. Alsawaf M, Missert W: Thesis. University of Pittsburgh, Department of Maxillofacial Surgery, Ear and Eye Hospital-Submitted for publication. 1989, J Prosthet Dent 40. Alsawaf M, Missert W: The relationship between condylar guidance and temporomandibular joint clicking. J Prosthet Dent 1989; 61 :349354 41. Missert W: Diagnostic splint therapy. J Clin Ortho 1989; XXIII:I82192 42. Missert W: Overlay splint therapy. J Clin Ortho 1989; XXIII:253-260 43. Curtise DA: A comparison of protrusive interocclusal records to pantographic tracings. J Prosthet Dent 1989; 62:23-27 44. Curtise DA: A comparison of protrusive interocclusal records to pantographic tracings. J Prosthet Dent 1989; 62:154-156
Robert M. Celar, M.D. Dr. Celar received his M.D. degree from the University of Vienna in 1989. In the fall of the same year he started working as a scientific collaborator at the Dental Clinic of the University of Vienna. In October 1990 he started the postgraduate dental education program at the Dental Clinic of the University of Vienna.
Rudolph Slavicek, M.D., D.D.S. Dr. Slavicek received special training in cardiology and pathology at the University of Vienna, Austria, and received his M.D. degree in 1954. He received his D.D.S. degree in 1957 with special studies in restoration and prosthetics. He is currently in private practice in Vienna and is head of the Dental Clinic Department of Removable and Fixed Prosthodontics at the University of Vienna. He is founding president of the European Academy of Craniomandibular Disorders.
THE JOURNAL OF CRANIOMANDIBULAR
PRACTICE
355
