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Effect of different centric relation registrations on the pantographic representation of centric relation
Effect of different centric relation registrations on the pantographic representation of centric relation Larry Sindledecker, Boca F&ton.
D.D.S.,
M.S. *
Fla.
B
efore attempting to analyze or treat a patient’s occlusion, the dentist must locate a reproducible reference position. Centric relation has often been used as this position. The purpose of this article is to: (1) measure the effect of three popular methods for recording centric relation on the pantographic representation of centric relation and (2) provide a means for collecting data directly on the patient.
LITERATURE
REVIEW
Definitions and methods for recording centric relation have long been controversial. Centric jaw relation is the most retruded physiologic relation of the mandible to the maxillae, to and from which the individual can make lateral movements. It is a condition which can exist at various degrees of jaw separation. It occurs around the terminal hinge axis. It is the most posterior relation of the mandible to the maxillae at the established vertical dimension.* Avant2 and Bouche? define centric relation as a bone-to-bone relation (mandible-to-maxillae), occurring as “the most posterior/superior relation of the mandible to the maxillae at the established vertical dimension.“’ Centric relation is also described as a functional position4 since some swallowing contacts have been shown to occur in centric relation; however, others have found few swallowing contacts in centric relation as monitored with transistors and thus discount centric relation as a functional position.’ Others state that swallowing occurs somewhere anterior to the most retruded position, and they refer to this anterior location as the ideal or centric relation position;+” at this anterior position the muscles, joints, teeth, and supporting structures
Presented at the Academy of Denture Prosthetics, Daytona Beach, Fla. *Clinical Associate Professor, Department of Occlusion and Fixed Prosthodontics, University of Florida, School of Dentistry, Gainesville, Fla.
OO22-3913/81/090271
+ 09$00.90/00
1981 The
C. V. Mosby
Co.
Fig. 1. Acrylic resin labial clutches cemented to teeth.
Fig. 2. Maxillary
modified occlusai clutch.
are in equilibrium. The followers of this concept discount the “retruded” centric relation position as a strained nonfunctional position. Still others have described centric relation as one point, and they reject the idea of multiple centric relations occurring Some have at different vertical dimensions.” expressed the idea that muscles have the limiting effect on the retruded movement to centric relation.‘“-‘” Other investigators state that in a powertransmission in a hinge movement, it is the muscles
THE JOURNAL OF PROSTHETIC DENTISTRY
271
SINDLEDECKER
Fig. 3. Mandibular modified occlusal clutch.
Fig. 5. Recording plate and receptacle.
Fig. 4. Modified pantographic on subject B,
and 1igament.s which control the osseous components of the joint.” In this movement, the pivot point is between the medial poles of the condyles and the facet area (point of bearing). Some authors state that the centric :relation is governed by capsular ligaments.‘“.” The term “centric relation” is meaningless unless the user gives his specific definition. Universal agreement concerning the meaning of centric relation will no doubt be long in coming. In the context of this article, centric relation will be considered as (1) the rearmost, uppermost, midmost position of the condyles in the glenoid fossae and (2) controlled by ligaments and muscles and located only when interferences from a tooth-programmed occlusion are eliminated. Continued interest and analysis will hopefully give the profession an improved method for verifying jaw position records, especially interocclusal centric relation records. Variables of cast accuracy, face-bow transfer, and plaster expansion plague the indirect means of testing jaw records. Length of appointment 272
Fig. 6. Posterior vertical receptacle in relation to Frankfort horizontal plane marked on skin for subject 8.
time, apparatus availability and attachment, patient tolerance, and fatigue all hinder the direct method of testing the accuracy of interocclusal centric relation records. MATERIAL
AND METHODS
This study compares different interocclusal records of centric relation with the use of a pantograph directly on the patient. The three patients selected from those who volunteered as subjects for this study, hereafter referred to as subjects A, B, or C, met the following criteria: 1. They were all free of subjective symptoms or signs of temporomandibular joint (TMJ) dysfunctions and/or traumatic occlusion. 2. They all had a sufficient number of natural teeth (or fixed restorations) to facilitate recordings and clutch attachments. They all had at least second molar occlusion and no removable restorations. SEPTEMBER
1981
VOLUME
46
NUMBER
3
PANTOGRAPHIC
REPRESENTATION
OF CENTRIC
RELATION
t Fig. 7. Centric relation wax interocclusal
Fig. 9. Centric
relation
OF PROSTHETIC
DENTISTRY
interocclusal
lens used to measure styli loca-
paste interoc-
3. None had any medical contraindications to the procedures used in the study. Occlusal splints were made and worn continuously for 2 to 3 months before recordings were attempted.” These splints helped “deprogram” the patients’ neuromuscular guidance to centric occlusion Interocclusal centric relation records were made and compared to the centric relation representation as illustrated on the tables of a pantograph, which was chosen because of the ease of attachment, availability, and accuracy (discreteness to 0.1 mm). Labial clutches were constructed to fit over the labial surfaces of the maxillary and mandibular anterior teeth without interference with the patient’s occlusion (Fig. 1). Modified pantographic clutches were also made (Figs. 2 and 3), and a modified pantograph was used to record measurement (Fig. 4). A THE JOURNAL
msin
record.
Fig. 10. Magnifying tions. Fig. 8. Centric relation zinc oxide-eugenol clusal record.
acrylic
recording plate holder (a receptacle), into which fit interchangeable rectangular recording plates milled to fit the receptacle, was placed on each pantographic table (Figs. 5 and 6). The receptacles can be adjusted on the tables using jewelers’ screws from the underside of the table. For example, the posterior vertical receptacle is positioned on l.he table so that the inferior surface of the receptacle is approximately parallel to the Frankfort horizontal plane of the patient. Variances were established for standardization of the placement of the pantograph on the patients and “zeroing” it into a reproducible position on each. Once the instrument was attached and “zeroed” (indicated by no visible arcing of any stylus), it was assumed that this was a pantographic representation of the patients’ centric relation position. Next, three popular methods for recording centric relation were tested while the pantographic anterior clutch attachments remained in pos:ition during the 273
SINDLEDECKER
Table I. Mean vaIues of coordinates
for methods
y
x
Y
x
Y
x
Y
2.26 7.44 4.18
10.43 4.75 6.41
2.3 7.6 4.18
10.48 4.64 8.06
2.33 7.59 4.16
10.39 4.49 7.93
2.32 7.63 4.2
10.48 4.58 8.42
2.44 6.53 1.73
11.63 5.91 8.93
2.42 6.34 1.69
11.37 5.9 4.17
2.39 6.36 1.63
11.37 5.99 4.19
2.44 6.40 1.72
11.42 6.02 6.02
2.84 7.15 5.46
8.35 3.12 6.52
2.81 7.14 5.73
8.52 3.14 7.82
2.81 7.18 5.73
8.53 3.13 7.81
2.79 7.07 5.72
8.52 3.13 8.19
between relation and materials-hypothesis: material - CR = 0
centric
recording
procedures:
paste,‘” and acrylic
x coordinate
y coordinate
NR NR NR R (0.19 mm) NR NR NR NR NR
NR NR NR R (0.17 mm) NR NR R (2 mm) R (0.36 mm) R (0.49 mm)
NR NR NR R (0.13 mm) NR NR NR NR NR
R (0.21 mm) NR NR NR NR NR R (2.91 mm) R (1.85 mm) R (1.83 mm)
NR NR NR NR NR R (0.12 mm) R (0.26 mm) NR NR
R (0.16 mm) NR NR NR NR NR R (1.68 mm) R (0.37 mm) R (0.38 mm)
wax,’
zinc
oxide-eugenol
resin.?”
With the centric relation record in place, the pantograph was reattached, and the styli were brought into contact with the recording plates. The mark left by each stylus could easily be compared to the one made before the record was taken. Similarly, different records could be compared (Figs. 7 to 9). Following the recording phase, measurements were made on an x and y coordinate system of each dot made on each recording plate. Each plate had been marked while positioned for anterior-posterior position on the patient. A standardized system was used for recording the data. The investigator read aloud each coordinate from a specific order of plate arrangement while another person recorded the measurements. Plates were measured in sets (all seven in order, when possible) to minimize any chance for memorization of previous coordinates from one plate to the next (Fig. 10).
RESULTS
Legen& W-CR = distance from centric relation to wax; PCR = distance from centric relation to paste; A-CR = distance from centric relation to acrylic resin. NR = hypothesis accepted (not rejected); R = hypothesis rejected.
274
Centric relation
Acrylic
x
Table II. Mean differences
Subject A RV W-CR P-CR A-CR LV W-CR P-CR A-CR AV W-CR P-CR A-CR Subject B RV W-CR P-CR A-CR LV W-CR P-CR A-CR AV W-CR. P-CR A-CR Subject C RV W-CR P-CR A-CR LV W-CR P-CR A-CR AV W-CR P-CR A-CR
relation
Paste
Wax
Subject A RV LV AV Subject B RV LV AV Subject C RV LV AV
and for centric
The purpose of this study was to determine the effect of different interocclusal centric relation records on the pantographic representation of centric relation. Since an x andy coordinate system was used to describe dot location, there was no need to determine the size of each dot. The results of this study were used to: (1) compare the means (both x and y components) of each recording material and (2) determine, approximately, changes in condylar directions as a result of recording procedures. The hypothesis that the styli
SEPTEMBER
1981
VOLUME
46
NUMBER
3
PANTOGRAPHIC
REPRESENTATION
Table III. Comparison
Dimensional differences
Comparison with centric relation
Warm baseplate wax
Wax wafer with metallic oxide paste Same Same Same Imprint plastic Swallowing
Zinc oxide-eugenol paste/jig
Chin-point guidance Chin-point guidance with anterior jig Bilateral manipulation Myo-Monitor Most variation
Operator guidance
Operator guidance
Patient closes freely
Operator guidance
Operator guidance Least variation
Least variation
Slightly less than 4 Little variation
Most variation
Most variation
Jig plus patient pulling back Operator guidance Patient closes freely
Equal to and 4 Unequal others Equal to and 4 Equal to and 3
3 to 1 I
Equal to 3 and 4 5 mm from I, 3, and 4 Equal to I and 4 Equal to 1 and 3 Not reported
Not reported Not reported Not reported No. of subjects No. of recordings per method
1 1
OF PROSTHETIC
DENTISTRY
StrohaveP
Wax (with Ash’s metal) Impression plaster Imprint plastic Acrylic resin/jig Operator guidance
Most reproducible More variation than 1 0.4 mm (mean variability) 0.14 mm same 0.07 mm same
0.568
same
0.05 mm same
1.142
same
Not reported Not reported
0.712 same Not reported
Not Not Not Not 1.5 6
Not Not Not Not 1 3 (3
reported reported reported reported
Zinc oxide-eugenol paste/jig Swissdent Wax Acrylic resin/jig
Chin-point
guidance
Myo-Monitor
Slightly more variation than 1 Slightly less variation than 2 Slightly more variation than 3 0.238 mm (mean variability) 1.575 mm same
illustration of wax, zinc oxide-eugenol paste, acrylic resin, and centric relation was the same was rejected for all patients at the) = .05 significance level. Mean (X andy) values for each subject for each material and for centric relation are shown in Table I. Figs. 11 to 13 illustrate the mean positions recorded on subjects A, B, and C on three vertical tables
THE JOURNAL
This study
KantoP
Chin-point guidance Reproducibility
studies
Long’
Same Same Same Method
RELATION
of this study with other similar
Study Material
OF CENTRIC
reported reported repotied reported operators)
Nearly same variation as 1
0.01-0.04 (range of variances) 0.02-0.35 same 0.02-0.05 same
0.~31-0.12 (range of mean difference) 0.13-0.21 same 0.01-0.11 same 0.01-0.11 same 3 27
only: right (RV), left (LV), and anterior (AV). These pantographic tables were most descriptive of condylar position and changes in vertical dimension. Also, directional arrows indicate the anterior direction approximately paralleling the Frankfort horizontal plane. Recall direction was recorded before the plates were removed from the instrument.
275
SINDLEDECKER
8.5
0
8.0 mm 7.5 7.0 6.5
A
6.0 L40
A
wux
0
Paste
n
Acrylic
0
Centric
C
Anlerior
Relation
4.1 4.2 43 4.4 4.5 II A" t",,
-4.9
10.6-
-48
IO.5-
-4.7 0
10.4mm
0
lO.3+
IO.2 I h 2.0 2.1
2 2 2.3 24
l
* 2.5
0,;;”
-4.6
A
mm
-4.5 -4.4
I , 4.3 > I 79 7.8 7.7 7.6 7.5 7.4 73 II ya,
Fig. 11. Mean comparison of three methods and centric relation on three recording plates for subject A. Further investigation compared mean differences in both the x and y components between centric relation and the position recorded with each method. Because these differences were expressed in x and y components, there could be a difference on one axis without a difference on the other. The hypothesis was that the difference (for both coordinates, separately) between centric relation and each material was zero. When rejected, the difference was an estimation of the difference between the two locations for that coordinate. When not rejected, the data indicated that the difference in coordinate locations was zero, and therefore, they were the same point (Table II).
DISCUSSIC)N Human variances should be established in a study of this nature, and variances of materials must be determined. Previous studies have not been in agreement with this attitude.2’-26 Of equal importance is the control of vertical dimension during recordings
276
of centric relation which has not been controlled in the previous studies. Whereas other studies have rounded values to the nearest 0.5 mm, this study has reported values in hundredths of millimeters,‘“. “’ and the quality of the data is directly related to the quantity of the data. This study collected a large amount of data on each patient, even though few patients were used. Occlusal splints were used to deprogram toothguided closures. While other studies have also utilized splint therapy for similar reasons,” the longterm effect of splints on condylar position has not been reported. The findings concerning direction in this study bear some resemblance to those previously reported.“” Unlike previous studies,‘” this experiment tested a new material-acrylic resin in the shape of overlays. As yet, this material has not received universal acceptance, which is all the most reason to compare its possibilities. While the method using wax differed from the
SEPTEMBER
1981
VOLUME
46
NUMBER
3
PANTOGRAPHIC
REPRESENTATION
OF CENTRIC
RELATION
1 A
95
A wox
7.5mm 6.5-
0
0
Paste
n
Acrylic
0
Centric
Relotion
Z Anterior
I.5
1.7 I.8 I.9 .r; v”n,
2.0
2.64
6.2
2.5-
6.1
2.4mm
I.6
0
A
6.0
2.3-
5.9 mm
2.2-
5.8
2.1, I 112 II3
* I 1 II.4 II.5
1 I II.6 II.7
II.8
>
6.7
I
6.6
,
6.5
6.4 6.3
6.2 6.1
Fig. 12. Mean comparison of three methods and centric relation on three recording plate:; for subject B. other methods,’ this should not be construed to mean that the wax method is unacceptable in clinical situations. It was not the purpose of this study to compare the materials from the standpoint of usage in complete mouth reconstruction procedures, and the method used is not suggested as a means for recording centric relation on complete mouth reconstruction patients. Paste and acrylic resin methods are suggested for this purpose. Table III compares this study with three other studies.
SUMMARY A study was designed to determine the effect of three different centric relation recording methods on the pantographic representation of centric relation. A modified pantograph was used as the measuring instrument. Variances for each method were established on one subject, and variance of location of
THE IOIJRNAL
OF PROSTHETIC
DENTISTRY
centric relation was established on two different subjects. Mean differences between recording methods and centric relation were established on three subjects. Wax was found to be the least reliable material tested and the least accurate for recording centric relation. CONCLUSIONS Conclusions based on this study include: 1. Centric relation is recorded within an area, rather than as a precise point. In this study, the range of this area depends on the material used: (1) wax, 0.21 mm; (2) zinc oxide-eugenol paste, 0.12 mm; and (3) acrylic resin, 0.11 mm. 2. Variances for recording methods and for location of centric relation are not transferable from one subject to another; however, values of variances can be compared from one subject to another. 3. At the 95% significance level, the reliability of
277
SINDLEDECKER
9.08.5-
P
8.0-
A
Wax
0
Paste
n
Acrylic
0
Centric
7.5-
mm 7.0-
Relation
4 Anterior
5.3
54
5.5 56
5.7
5.8
5.9
‘12.8 7.4 73
12
ZI
,,“a; I,
2.5
2.6
2.7
2.8
29
3.0
3.1
mm ” Lv ”
70
6.9
6.8
mm “Lv”
Fig. 13. Mean comparison of three methods and centric relation on three recording plates for subject C.
interocclusal wax records for recording a point in space was less than for other methods. 4. At the 95% significance level, wax gave statistically different centric relation registrations from those of zinc oxide-eugenol paste or acrylic resin.
6.
DENT 6:350,
7. 8.
I would like to thank Dr. Joseph Clayton, Dr. Hart Long, Ms. Marsha Steward, and Ms. Phyllis Gimothy for their help in preparation of this article.
9. 10.
REFERENCES 1. Glossary of Prosthodontics Terms: J PROSTWET DENT 20:452,
11.
1968.
2.
Avant, W. E.: Using the term “centric.”
3.
Boucher, C. 0. (editor): Swenson’s Complete Dentures, ed 5. St. Louis, 1964, The C. V. Mosby Co., pp 176-214. Ramfjord, S. P., and Ash, M. M.: Occlusion. Philadelphia, 1971, W. B. Saunders Co., pp 204-209. Glickman, I., Pameijer, J., Roeber, F., and Brain, M.:
25:12,
4. 5.
278
Functional occlusion as revealed by miniaturized radio transmitters. Dent Clin North Am 13:667, 1969. Nagle, R. J.: Temporomandibular function. J PROSTHET
J PROSTHET DENT
1971.
12. 13. 14.
1956.
Shanahan, T. E. J,: Physiologic vertical dimension and centric relation. J PROSTHET DENT 6:741, 1956. Meyers, R. E.: Some physiologic considerations of centric and other jaw relations. J PROSTHET DENT 6:183, 1956. Holic, R.: Centric registration in full denture construction. J Am Dent Assoc 36:296, 1948. Bar, U., and Brill, N.: Modern concepts of reflexes and registrations to obtain centric occlusion and centric relation in prosthetic dentistry. Dent Abstracts 4:7, 1959. Silverman, S. I.: Denture prosthesis and the functional anatomy of the maxillofacial structures. J PROSTHET DENT 6:305, 1956. Kingery, R. H.: Review of some of the problems associated with centric relation. J PROSTHET DENT 2:307, 1952. Boucher, L. J,: Limiting factors in posterior movement of mandibular condyles. J PROSTHET DENT 11:23, 1961. Boucher, L. J.: Anatomy of the temporomandibular joint as
SEPTEMBER
1981
VOLUME
46
NUMBER
3
PANTOGRAPHIC
REPRESENTATION
OF CENTRIC
RELATION
it pertains to centric relation. J PROSTHET DENT 12:464, 1962. 15. Cohen, R.: The hinge axis and its practical application in determination of centric relation. J PROSTHET DENT 10:248. 1960. 16. &anger, E. R.: Centric relation. J PROSTHET DENT 2:160,
23. 24. 25.
1952.
17. Zola, A.: Morphologic limiting factors in the temporomandibular joint. J PROSTHE~DENT 13:732, 1963. 18. Sicher, H.: Oral Anatomy, ed 4. St. Louis, 1965, The C. V. Mosby Co., pp 183-186. 19. Aprile, H., and Saizar, P.: Gothic arch tracing and temporomandibular anatomy. J Am Dent Assoc 35:256, 1947. 20. Arstad, T.: The capsular ligaments of the temporomandibular joint and retrusion facets of the dentition in relationship to mandibular movements. Oslo, 1954, Akademisk Forlag. 21. Posselt, U.: Studies in the mobility of the human mandible. Acta Odontol Stand vol. 10, suppl. 10, 1952. 22. Lucia, V. 0.: A technique for recording centric relation. J PROUHET DENT 14:492, 1964.
THE JOURNAL
OF PROSTHETIC
DENTLSTRY’
26.
27.
Zarb, G.: Prosthodontic Treatment for Partially Edentulous Patients. St. Louis, 1978, The C. V. Mosby Co., p 183. Long, J. H.: Location of the terminal hinge axis by intraoral means. J PROSTHET DENT 23:11, 1970. Strohaver, R. A.: A comparison of articulator mountings made with centric relation and myocentric position records. J PROSTHETDENT 28:379, 1972. Kantor, M. E., Silverman, S. I., and Garfinkel, L.: Centricrelation recording techniques. A comparative investigation. J PROWHET DENT 28:593, 1972. Posselt, U.: An analyzer for mandibular positions. J PROSWET DENT 7:368,
28.
1957.
McMillen, L. B.: Border movements of the human mandible. J PROSTHET DENT 27:524, 1972.
Reprint requeststo: DR. LARRY SENDLEDECKER 333 W. CAMINO GARDENS BLVD. BOCA RATON, FL 33432
279
D.D.S.,
M.S. *
Fla.
B
efore attempting to analyze or treat a patient’s occlusion, the dentist must locate a reproducible reference position. Centric relation has often been used as this position. The purpose of this article is to: (1) measure the effect of three popular methods for recording centric relation on the pantographic representation of centric relation and (2) provide a means for collecting data directly on the patient.
LITERATURE
REVIEW
Definitions and methods for recording centric relation have long been controversial. Centric jaw relation is the most retruded physiologic relation of the mandible to the maxillae, to and from which the individual can make lateral movements. It is a condition which can exist at various degrees of jaw separation. It occurs around the terminal hinge axis. It is the most posterior relation of the mandible to the maxillae at the established vertical dimension.* Avant2 and Bouche? define centric relation as a bone-to-bone relation (mandible-to-maxillae), occurring as “the most posterior/superior relation of the mandible to the maxillae at the established vertical dimension.“’ Centric relation is also described as a functional position4 since some swallowing contacts have been shown to occur in centric relation; however, others have found few swallowing contacts in centric relation as monitored with transistors and thus discount centric relation as a functional position.’ Others state that swallowing occurs somewhere anterior to the most retruded position, and they refer to this anterior location as the ideal or centric relation position;+” at this anterior position the muscles, joints, teeth, and supporting structures
Presented at the Academy of Denture Prosthetics, Daytona Beach, Fla. *Clinical Associate Professor, Department of Occlusion and Fixed Prosthodontics, University of Florida, School of Dentistry, Gainesville, Fla.
OO22-3913/81/090271
+ 09$00.90/00
1981 The
C. V. Mosby
Co.
Fig. 1. Acrylic resin labial clutches cemented to teeth.
Fig. 2. Maxillary
modified occlusai clutch.
are in equilibrium. The followers of this concept discount the “retruded” centric relation position as a strained nonfunctional position. Still others have described centric relation as one point, and they reject the idea of multiple centric relations occurring Some have at different vertical dimensions.” expressed the idea that muscles have the limiting effect on the retruded movement to centric relation.‘“-‘” Other investigators state that in a powertransmission in a hinge movement, it is the muscles
THE JOURNAL OF PROSTHETIC DENTISTRY
271
SINDLEDECKER
Fig. 3. Mandibular modified occlusal clutch.
Fig. 5. Recording plate and receptacle.
Fig. 4. Modified pantographic on subject B,
and 1igament.s which control the osseous components of the joint.” In this movement, the pivot point is between the medial poles of the condyles and the facet area (point of bearing). Some authors state that the centric :relation is governed by capsular ligaments.‘“.” The term “centric relation” is meaningless unless the user gives his specific definition. Universal agreement concerning the meaning of centric relation will no doubt be long in coming. In the context of this article, centric relation will be considered as (1) the rearmost, uppermost, midmost position of the condyles in the glenoid fossae and (2) controlled by ligaments and muscles and located only when interferences from a tooth-programmed occlusion are eliminated. Continued interest and analysis will hopefully give the profession an improved method for verifying jaw position records, especially interocclusal centric relation records. Variables of cast accuracy, face-bow transfer, and plaster expansion plague the indirect means of testing jaw records. Length of appointment 272
Fig. 6. Posterior vertical receptacle in relation to Frankfort horizontal plane marked on skin for subject 8.
time, apparatus availability and attachment, patient tolerance, and fatigue all hinder the direct method of testing the accuracy of interocclusal centric relation records. MATERIAL
AND METHODS
This study compares different interocclusal records of centric relation with the use of a pantograph directly on the patient. The three patients selected from those who volunteered as subjects for this study, hereafter referred to as subjects A, B, or C, met the following criteria: 1. They were all free of subjective symptoms or signs of temporomandibular joint (TMJ) dysfunctions and/or traumatic occlusion. 2. They all had a sufficient number of natural teeth (or fixed restorations) to facilitate recordings and clutch attachments. They all had at least second molar occlusion and no removable restorations. SEPTEMBER
1981
VOLUME
46
NUMBER
3
PANTOGRAPHIC
REPRESENTATION
OF CENTRIC
RELATION
t Fig. 7. Centric relation wax interocclusal
Fig. 9. Centric
relation
OF PROSTHETIC
DENTISTRY
interocclusal
lens used to measure styli loca-
paste interoc-
3. None had any medical contraindications to the procedures used in the study. Occlusal splints were made and worn continuously for 2 to 3 months before recordings were attempted.” These splints helped “deprogram” the patients’ neuromuscular guidance to centric occlusion Interocclusal centric relation records were made and compared to the centric relation representation as illustrated on the tables of a pantograph, which was chosen because of the ease of attachment, availability, and accuracy (discreteness to 0.1 mm). Labial clutches were constructed to fit over the labial surfaces of the maxillary and mandibular anterior teeth without interference with the patient’s occlusion (Fig. 1). Modified pantographic clutches were also made (Figs. 2 and 3), and a modified pantograph was used to record measurement (Fig. 4). A THE JOURNAL
msin
record.
Fig. 10. Magnifying tions. Fig. 8. Centric relation zinc oxide-eugenol clusal record.
acrylic
recording plate holder (a receptacle), into which fit interchangeable rectangular recording plates milled to fit the receptacle, was placed on each pantographic table (Figs. 5 and 6). The receptacles can be adjusted on the tables using jewelers’ screws from the underside of the table. For example, the posterior vertical receptacle is positioned on l.he table so that the inferior surface of the receptacle is approximately parallel to the Frankfort horizontal plane of the patient. Variances were established for standardization of the placement of the pantograph on the patients and “zeroing” it into a reproducible position on each. Once the instrument was attached and “zeroed” (indicated by no visible arcing of any stylus), it was assumed that this was a pantographic representation of the patients’ centric relation position. Next, three popular methods for recording centric relation were tested while the pantographic anterior clutch attachments remained in pos:ition during the 273
SINDLEDECKER
Table I. Mean vaIues of coordinates
for methods
y
x
Y
x
Y
x
Y
2.26 7.44 4.18
10.43 4.75 6.41
2.3 7.6 4.18
10.48 4.64 8.06
2.33 7.59 4.16
10.39 4.49 7.93
2.32 7.63 4.2
10.48 4.58 8.42
2.44 6.53 1.73
11.63 5.91 8.93
2.42 6.34 1.69
11.37 5.9 4.17
2.39 6.36 1.63
11.37 5.99 4.19
2.44 6.40 1.72
11.42 6.02 6.02
2.84 7.15 5.46
8.35 3.12 6.52
2.81 7.14 5.73
8.52 3.14 7.82
2.81 7.18 5.73
8.53 3.13 7.81
2.79 7.07 5.72
8.52 3.13 8.19
between relation and materials-hypothesis: material - CR = 0
centric
recording
procedures:
paste,‘” and acrylic
x coordinate
y coordinate
NR NR NR R (0.19 mm) NR NR NR NR NR
NR NR NR R (0.17 mm) NR NR R (2 mm) R (0.36 mm) R (0.49 mm)
NR NR NR R (0.13 mm) NR NR NR NR NR
R (0.21 mm) NR NR NR NR NR R (2.91 mm) R (1.85 mm) R (1.83 mm)
NR NR NR NR NR R (0.12 mm) R (0.26 mm) NR NR
R (0.16 mm) NR NR NR NR NR R (1.68 mm) R (0.37 mm) R (0.38 mm)
wax,’
zinc
oxide-eugenol
resin.?”
With the centric relation record in place, the pantograph was reattached, and the styli were brought into contact with the recording plates. The mark left by each stylus could easily be compared to the one made before the record was taken. Similarly, different records could be compared (Figs. 7 to 9). Following the recording phase, measurements were made on an x and y coordinate system of each dot made on each recording plate. Each plate had been marked while positioned for anterior-posterior position on the patient. A standardized system was used for recording the data. The investigator read aloud each coordinate from a specific order of plate arrangement while another person recorded the measurements. Plates were measured in sets (all seven in order, when possible) to minimize any chance for memorization of previous coordinates from one plate to the next (Fig. 10).
RESULTS
Legen& W-CR = distance from centric relation to wax; PCR = distance from centric relation to paste; A-CR = distance from centric relation to acrylic resin. NR = hypothesis accepted (not rejected); R = hypothesis rejected.
274
Centric relation
Acrylic
x
Table II. Mean differences
Subject A RV W-CR P-CR A-CR LV W-CR P-CR A-CR AV W-CR P-CR A-CR Subject B RV W-CR P-CR A-CR LV W-CR P-CR A-CR AV W-CR. P-CR A-CR Subject C RV W-CR P-CR A-CR LV W-CR P-CR A-CR AV W-CR P-CR A-CR
relation
Paste
Wax
Subject A RV LV AV Subject B RV LV AV Subject C RV LV AV
and for centric
The purpose of this study was to determine the effect of different interocclusal centric relation records on the pantographic representation of centric relation. Since an x andy coordinate system was used to describe dot location, there was no need to determine the size of each dot. The results of this study were used to: (1) compare the means (both x and y components) of each recording material and (2) determine, approximately, changes in condylar directions as a result of recording procedures. The hypothesis that the styli
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Table III. Comparison
Dimensional differences
Comparison with centric relation
Warm baseplate wax
Wax wafer with metallic oxide paste Same Same Same Imprint plastic Swallowing
Zinc oxide-eugenol paste/jig
Chin-point guidance Chin-point guidance with anterior jig Bilateral manipulation Myo-Monitor Most variation
Operator guidance
Operator guidance
Patient closes freely
Operator guidance
Operator guidance Least variation
Least variation
Slightly less than 4 Little variation
Most variation
Most variation
Jig plus patient pulling back Operator guidance Patient closes freely
Equal to and 4 Unequal others Equal to and 4 Equal to and 3
3 to 1 I
Equal to 3 and 4 5 mm from I, 3, and 4 Equal to I and 4 Equal to 1 and 3 Not reported
Not reported Not reported Not reported No. of subjects No. of recordings per method
1 1
OF PROSTHETIC
DENTISTRY
StrohaveP
Wax (with Ash’s metal) Impression plaster Imprint plastic Acrylic resin/jig Operator guidance
Most reproducible More variation than 1 0.4 mm (mean variability) 0.14 mm same 0.07 mm same
0.568
same
0.05 mm same
1.142
same
Not reported Not reported
0.712 same Not reported
Not Not Not Not 1.5 6
Not Not Not Not 1 3 (3
reported reported reported reported
Zinc oxide-eugenol paste/jig Swissdent Wax Acrylic resin/jig
Chin-point
guidance
Myo-Monitor
Slightly more variation than 1 Slightly less variation than 2 Slightly more variation than 3 0.238 mm (mean variability) 1.575 mm same
illustration of wax, zinc oxide-eugenol paste, acrylic resin, and centric relation was the same was rejected for all patients at the) = .05 significance level. Mean (X andy) values for each subject for each material and for centric relation are shown in Table I. Figs. 11 to 13 illustrate the mean positions recorded on subjects A, B, and C on three vertical tables
THE JOURNAL
This study
KantoP
Chin-point guidance Reproducibility
studies
Long’
Same Same Same Method
RELATION
of this study with other similar
Study Material
OF CENTRIC
reported reported repotied reported operators)
Nearly same variation as 1
0.01-0.04 (range of variances) 0.02-0.35 same 0.02-0.05 same
0.~31-0.12 (range of mean difference) 0.13-0.21 same 0.01-0.11 same 0.01-0.11 same 3 27
only: right (RV), left (LV), and anterior (AV). These pantographic tables were most descriptive of condylar position and changes in vertical dimension. Also, directional arrows indicate the anterior direction approximately paralleling the Frankfort horizontal plane. Recall direction was recorded before the plates were removed from the instrument.
275
SINDLEDECKER
8.5
0
8.0 mm 7.5 7.0 6.5
A
6.0 L40
A
wux
0
Paste
n
Acrylic
0
Centric
C
Anlerior
Relation
4.1 4.2 43 4.4 4.5 II A" t",,
-4.9
10.6-
-48
IO.5-
-4.7 0
10.4mm
0
lO.3+
IO.2 I h 2.0 2.1
2 2 2.3 24
l
* 2.5
0,;;”
-4.6
A
mm
-4.5 -4.4
I , 4.3 > I 79 7.8 7.7 7.6 7.5 7.4 73 II ya,
Fig. 11. Mean comparison of three methods and centric relation on three recording plates for subject A. Further investigation compared mean differences in both the x and y components between centric relation and the position recorded with each method. Because these differences were expressed in x and y components, there could be a difference on one axis without a difference on the other. The hypothesis was that the difference (for both coordinates, separately) between centric relation and each material was zero. When rejected, the difference was an estimation of the difference between the two locations for that coordinate. When not rejected, the data indicated that the difference in coordinate locations was zero, and therefore, they were the same point (Table II).
DISCUSSIC)N Human variances should be established in a study of this nature, and variances of materials must be determined. Previous studies have not been in agreement with this attitude.2’-26 Of equal importance is the control of vertical dimension during recordings
276
of centric relation which has not been controlled in the previous studies. Whereas other studies have rounded values to the nearest 0.5 mm, this study has reported values in hundredths of millimeters,‘“. “’ and the quality of the data is directly related to the quantity of the data. This study collected a large amount of data on each patient, even though few patients were used. Occlusal splints were used to deprogram toothguided closures. While other studies have also utilized splint therapy for similar reasons,” the longterm effect of splints on condylar position has not been reported. The findings concerning direction in this study bear some resemblance to those previously reported.“” Unlike previous studies,‘” this experiment tested a new material-acrylic resin in the shape of overlays. As yet, this material has not received universal acceptance, which is all the most reason to compare its possibilities. While the method using wax differed from the
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1 A
95
A wox
7.5mm 6.5-
0
0
Paste
n
Acrylic
0
Centric
Relotion
Z Anterior
I.5
1.7 I.8 I.9 .r; v”n,
2.0
2.64
6.2
2.5-
6.1
2.4mm
I.6
0
A
6.0
2.3-
5.9 mm
2.2-
5.8
2.1, I 112 II3
* I 1 II.4 II.5
1 I II.6 II.7
II.8
>
6.7
I
6.6
,
6.5
6.4 6.3
6.2 6.1
Fig. 12. Mean comparison of three methods and centric relation on three recording plate:; for subject B. other methods,’ this should not be construed to mean that the wax method is unacceptable in clinical situations. It was not the purpose of this study to compare the materials from the standpoint of usage in complete mouth reconstruction procedures, and the method used is not suggested as a means for recording centric relation on complete mouth reconstruction patients. Paste and acrylic resin methods are suggested for this purpose. Table III compares this study with three other studies.
SUMMARY A study was designed to determine the effect of three different centric relation recording methods on the pantographic representation of centric relation. A modified pantograph was used as the measuring instrument. Variances for each method were established on one subject, and variance of location of
THE IOIJRNAL
OF PROSTHETIC
DENTISTRY
centric relation was established on two different subjects. Mean differences between recording methods and centric relation were established on three subjects. Wax was found to be the least reliable material tested and the least accurate for recording centric relation. CONCLUSIONS Conclusions based on this study include: 1. Centric relation is recorded within an area, rather than as a precise point. In this study, the range of this area depends on the material used: (1) wax, 0.21 mm; (2) zinc oxide-eugenol paste, 0.12 mm; and (3) acrylic resin, 0.11 mm. 2. Variances for recording methods and for location of centric relation are not transferable from one subject to another; however, values of variances can be compared from one subject to another. 3. At the 95% significance level, the reliability of
277
SINDLEDECKER
9.08.5-
P
8.0-
A
Wax
0
Paste
n
Acrylic
0
Centric
7.5-
mm 7.0-
Relation
4 Anterior
5.3
54
5.5 56
5.7
5.8
5.9
‘12.8 7.4 73
12
ZI
,,“a; I,
2.5
2.6
2.7
2.8
29
3.0
3.1
mm ” Lv ”
70
6.9
6.8
mm “Lv”
Fig. 13. Mean comparison of three methods and centric relation on three recording plates for subject C.
interocclusal wax records for recording a point in space was less than for other methods. 4. At the 95% significance level, wax gave statistically different centric relation registrations from those of zinc oxide-eugenol paste or acrylic resin.
6.
DENT 6:350,
7. 8.
I would like to thank Dr. Joseph Clayton, Dr. Hart Long, Ms. Marsha Steward, and Ms. Phyllis Gimothy for their help in preparation of this article.
9. 10.
REFERENCES 1. Glossary of Prosthodontics Terms: J PROSTWET DENT 20:452,
11.
1968.
2.
Avant, W. E.: Using the term “centric.”
3.
Boucher, C. 0. (editor): Swenson’s Complete Dentures, ed 5. St. Louis, 1964, The C. V. Mosby Co., pp 176-214. Ramfjord, S. P., and Ash, M. M.: Occlusion. Philadelphia, 1971, W. B. Saunders Co., pp 204-209. Glickman, I., Pameijer, J., Roeber, F., and Brain, M.:
25:12,
4. 5.
278
Functional occlusion as revealed by miniaturized radio transmitters. Dent Clin North Am 13:667, 1969. Nagle, R. J.: Temporomandibular function. J PROSTHET
J PROSTHET DENT
1971.
12. 13. 14.
1956.
Shanahan, T. E. J,: Physiologic vertical dimension and centric relation. J PROSTHET DENT 6:741, 1956. Meyers, R. E.: Some physiologic considerations of centric and other jaw relations. J PROSTHET DENT 6:183, 1956. Holic, R.: Centric registration in full denture construction. J Am Dent Assoc 36:296, 1948. Bar, U., and Brill, N.: Modern concepts of reflexes and registrations to obtain centric occlusion and centric relation in prosthetic dentistry. Dent Abstracts 4:7, 1959. Silverman, S. I.: Denture prosthesis and the functional anatomy of the maxillofacial structures. J PROSTHET DENT 6:305, 1956. Kingery, R. H.: Review of some of the problems associated with centric relation. J PROSTHET DENT 2:307, 1952. Boucher, L. J,: Limiting factors in posterior movement of mandibular condyles. J PROSTHET DENT 11:23, 1961. Boucher, L. J.: Anatomy of the temporomandibular joint as
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PANTOGRAPHIC
REPRESENTATION
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RELATION
it pertains to centric relation. J PROSTHET DENT 12:464, 1962. 15. Cohen, R.: The hinge axis and its practical application in determination of centric relation. J PROSTHET DENT 10:248. 1960. 16. &anger, E. R.: Centric relation. J PROSTHET DENT 2:160,
23. 24. 25.
1952.
17. Zola, A.: Morphologic limiting factors in the temporomandibular joint. J PROSTHE~DENT 13:732, 1963. 18. Sicher, H.: Oral Anatomy, ed 4. St. Louis, 1965, The C. V. Mosby Co., pp 183-186. 19. Aprile, H., and Saizar, P.: Gothic arch tracing and temporomandibular anatomy. J Am Dent Assoc 35:256, 1947. 20. Arstad, T.: The capsular ligaments of the temporomandibular joint and retrusion facets of the dentition in relationship to mandibular movements. Oslo, 1954, Akademisk Forlag. 21. Posselt, U.: Studies in the mobility of the human mandible. Acta Odontol Stand vol. 10, suppl. 10, 1952. 22. Lucia, V. 0.: A technique for recording centric relation. J PROUHET DENT 14:492, 1964.
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OF PROSTHETIC
DENTLSTRY’
26.
27.
Zarb, G.: Prosthodontic Treatment for Partially Edentulous Patients. St. Louis, 1978, The C. V. Mosby Co., p 183. Long, J. H.: Location of the terminal hinge axis by intraoral means. J PROSTHET DENT 23:11, 1970. Strohaver, R. A.: A comparison of articulator mountings made with centric relation and myocentric position records. J PROSTHETDENT 28:379, 1972. Kantor, M. E., Silverman, S. I., and Garfinkel, L.: Centricrelation recording techniques. A comparative investigation. J PROWHET DENT 28:593, 1972. Posselt, U.: An analyzer for mandibular positions. J PROSWET DENT 7:368,
28.
1957.
McMillen, L. B.: Border movements of the human mandible. J PROSTHET DENT 27:524, 1972.
Reprint requeststo: DR. LARRY SENDLEDECKER 333 W. CAMINO GARDENS BLVD. BOCA RATON, FL 33432
279