- Email: [email protected]
An articulator recording tridimensional condyle movements using impression materials
An articulator recording tridimensional movements using impression materials
condyle
F. Sweijd, L.T.H. * Vrije Universiteit
Brussels, Brussels, Belgium
1
he practical purpose of an articulator is to mimic in the technician’s laboratory all movements of the mandible and the condyles.‘-’ To describe the complexity of condyle movements, some defined positions of the jaws have been considered as starting points5 ’ Thus the Gothic arch of Gysi and the hinge axis are recorded to define the centric relation.‘-” Individual lateral movements and the protrusive jaw relation were further recorded on wax records to determine respectively the Bennett shift and the condylar track inclinations.” ‘I The sum of these different dam was transferred to an articulator to obtain a tridimensional expression of reciprocal jaw movements at defined vertical dimensions.” The reliability of articulators is the subject of frequent discussions because they are restricted to the extreme positions, disregard all intermediary positions. and because of uncertainty about the accuracy of measurements of extreme positions.‘“-?’ We have built a face-bow with arbitrarily located condyles which form a pseudocondyle cavity in impression material placed laterally from the auditory canals. The shape of the pseudocondyles are oblong so that they can carry out only the movements which have formed the cavity, that is, all extreme and intermediary movements of the mandible.
DESCRIPTION INSTRUMENT
OF THE RECORDING
The recording instrument consists of two parts: 1. A face-bow built with such solidity that deformations by pressure during recording are excluded. Its extremities, rather than consisting of a needle point, have an ovoid shape (Fig. 1). 2. A helmet (headpiece) that can be affixed to the *Departmrnt
156
of Dental
AUGUST
1980
Prosthesis
VOLUME
44
NUMBER
2
head. Laterally, at the level of the auditory canals, two receptacles contain the impression materials, and polymethylmethacrylate plaster of paris (Fig. 2).
TECHNIQUE
AND RESULTS
The helmet is first attached to the patient’s head so that it is immobile. A splint made previously on a plaster cast of the maxillary teeth (not covering the occlusal surfaces of these teeth) is joined to the helmet. The splint constitutes the link between the latter pseudocondyle cavities and the maxillae, and it also contributes to the immobility of the headpiece. Another splint, again not covering the occlusal surfaces fixed to the mandible. The face-bow is affixed to this splint, and the pseudocondyles are adjusted to a position corresponding to the level of the hinge axes. One lateral receptacle is filled with impression plaster. The metal pseudocondyle is covered with petroleum jelly and pushed into the unset plaster. The patient then carries out a series of jaw movements in the vicinity of the centric relation, protrusive, lateral, and wide opening movements (Figs. 3 to 8). .4fter the plaster has set, the recording for the other side is performed. To remove “premature contacts” between the plaster and the pseudocondyles, corrections are made with a knife. In a second phase the polymethylmethacrylate is introduced into the pseudocondyle cavities. The patient then repeats all of the movements. The instrument is removed from the head and the splints are fit to maxillary and mandibular plaster casts. The classical positions of the centric relation, the protrusive jaiv relation, and the individual lateral movements, as well as a few arbitrary positions are
OOZ-3913/80/080156
+ 05$00.50/08
1980 The C. V. Mosby Co.
ARTICULATOR
RECORDING
TRIDIMENSIONAL
CONDYLE
MOVEMENTS
Fig. 1. Headpiece with lateral receptacles for impression material, to which a maxillary (lower right) can be affixed.
Fig. 2. Face-bow pseudocondyles.
fixed by the splint
to the mandible.
then recorded on the instrument [now the articulator) with wax records. Two pseudocondyle cavities are now formed by the tridimensional movements of the pseudocondyles in the impression material. The walls of these cavities represent the extreme movements of the pseudocondyles. The recorded wax records are then checked in the mouth. This ascertains that the mouth and articulator records are interchangeable.
THE JOURNAL
OF PROSTHETIC
DENTISTRY
Note the ovoid
splint
shape of the
DISCUSSION The proposed tridimensional recording device has the advantage of recording all condylar movements carried out by the mandible. The recording comprises not only the classical measurements such as the centric relation, lateral movements, and protrusive jaw relations, but also all intermediary movements. It increases the likelihood that no unique movement will be omitted.
157
SWEIJD
Fig. 3. Patient in occlusion near centric relation.
Fig. 4. Pseudocondyle in maximally
backward and uppermost position.
Fig. 5. Small opening of the mandible.
158
AUGUST 1980
VOLUME 44
NUMBER 2
ARTICULATOR
RECORDING
TRIDIMENSIONAL
Fig.
CONDYLE
6.
MOVEMENTS
Pseudocondyle in intermediary
Fig. 7. Maximal
position.
opening of the jaws.
Fig. 8. Extreme opening registration.
THE JOURNAL
OF PROSTHETIC
DENTISTRY
159
SWEIJD
SUMMARY
12
A recording
instrument was constructed which also functions as an articulator. It consists of a face-bow with pseudocondyles which forms pseudocondyle cavities in impression material placed laterally from the auditory canals. Occlusal registrations were interchangeable on the articulator and in the mouth. REFERENCES I 2. 3 4 5. 6.
7. 8
9 10.
11.
160
Shanahan. T E. J , and Leff. A : Mandtbular and articulator movements. J PROSTHET DENT 6:941. 1959. Kurth, L. E. Physics of mandibular movement related to full denture construction. J PROSTHET DENT 4:61 I. 1954 Giffen. i*: .4. Registration of mandtbular movements wth plastic material. J Am Dent .4ssoc 14:1480, 1927. Bra\\ n, A H. Movements of the mandible not provided for in present dav articulators. J Am Dent izssoc 17:982. 1930 Needles,J W Mandibular movements and occlusion J Am Dent .4ssmx 14:786, 1927. DiPietro, G. J., and Moergeli, J. R.: Significance of the Frankfort-mandibular plane angle to prosthodontics. J PROSTHET DEYT 36:624, 1976 Borgh. 0. and Posselt, U: Hinge axis registration on articulator J PROWHET DENT 8:35, 1958. Cohen. R.. The hinge axis and its practical application in the determination of crntric relation. J PROSTHET DENT 10:248. 1960. Hughes. G. .4, and Regli, C. P : What is centric relation? J PROSTHI:T DENT 11316, 1961. Boucher. C 0 : Method of recording functIona movements of full-denture bases in three dimensions. J Dent Res 14:39. 1934. Gysi. A.: .4n analysis of the development of the articulator J Am Dent .4ssoc 17:1401, 1930
13. 14. 15.
16.
17.
18.
19. 20.
21.
M’einberg, L. .4.: The occlusal plane and cuspal inclination in relation to incisal condylar guidance for protrusive excursions. J PROSWET DENT 9:6Oi. 1959 Benson, C. W : Condylar guidance. J Am Dent Assoc 19:1591. 1932 Hanau, R L Arttculation defined. analyzed. and formulated. J Am Dent .4ssoc 13:1694, 1926 IYeinberg. L. A : An evaluanon of basic artrculators and thew concepts. Part I Baw concepts. J PROSTHET DENT 13:622. 1963 IVeinberg, L. .4 : An evaluation of basic articulators and their concepts. Part I\’ Fullv adjustable articulators. J PROSTHET DENT 13:1038. 1963. Beck. D. B.. and Knap. F. J.: Reliabilitv of fully adjustable articulators using a computewed analysts J PROSTHET DENT 35:630, 19i6 Finger. I hf.. Foreman. D., and Tanaka, H : Optical method for articulator comparison and Ftudy of occlusal determinants J Dent Res 55:1042, 19i6 Atkinson, H F. Occlusion A mbth or a must. Aust Dent J 21:334. 1967. Hughes, G. A: Discussion of “Factors Influencing centric relation records in edentulous mouths ” J PROSTHET DENT 14:1066, 1964 Yurkstas, A A., and Kapur, K. K: Factors influencing centric relation records in edentulous mouths J PROSTHET DENT 14:1054. 1964
Rejmnt requeststo. DR. F. SWEIJD \‘RIJE UNIVERSITEIT BRUSSEL FNWLTEIT GENEESKUNDE LAARBEEKLAAN 101 1090 BRUSSELS BELGILW
AUGUST
1980
VOLUME
44
NUMBER
2
condyle
F. Sweijd, L.T.H. * Vrije Universiteit
Brussels, Brussels, Belgium
1
he practical purpose of an articulator is to mimic in the technician’s laboratory all movements of the mandible and the condyles.‘-’ To describe the complexity of condyle movements, some defined positions of the jaws have been considered as starting points5 ’ Thus the Gothic arch of Gysi and the hinge axis are recorded to define the centric relation.‘-” Individual lateral movements and the protrusive jaw relation were further recorded on wax records to determine respectively the Bennett shift and the condylar track inclinations.” ‘I The sum of these different dam was transferred to an articulator to obtain a tridimensional expression of reciprocal jaw movements at defined vertical dimensions.” The reliability of articulators is the subject of frequent discussions because they are restricted to the extreme positions, disregard all intermediary positions. and because of uncertainty about the accuracy of measurements of extreme positions.‘“-?’ We have built a face-bow with arbitrarily located condyles which form a pseudocondyle cavity in impression material placed laterally from the auditory canals. The shape of the pseudocondyles are oblong so that they can carry out only the movements which have formed the cavity, that is, all extreme and intermediary movements of the mandible.
DESCRIPTION INSTRUMENT
OF THE RECORDING
The recording instrument consists of two parts: 1. A face-bow built with such solidity that deformations by pressure during recording are excluded. Its extremities, rather than consisting of a needle point, have an ovoid shape (Fig. 1). 2. A helmet (headpiece) that can be affixed to the *Departmrnt
156
of Dental
AUGUST
1980
Prosthesis
VOLUME
44
NUMBER
2
head. Laterally, at the level of the auditory canals, two receptacles contain the impression materials, and polymethylmethacrylate plaster of paris (Fig. 2).
TECHNIQUE
AND RESULTS
The helmet is first attached to the patient’s head so that it is immobile. A splint made previously on a plaster cast of the maxillary teeth (not covering the occlusal surfaces of these teeth) is joined to the helmet. The splint constitutes the link between the latter pseudocondyle cavities and the maxillae, and it also contributes to the immobility of the headpiece. Another splint, again not covering the occlusal surfaces fixed to the mandible. The face-bow is affixed to this splint, and the pseudocondyles are adjusted to a position corresponding to the level of the hinge axes. One lateral receptacle is filled with impression plaster. The metal pseudocondyle is covered with petroleum jelly and pushed into the unset plaster. The patient then carries out a series of jaw movements in the vicinity of the centric relation, protrusive, lateral, and wide opening movements (Figs. 3 to 8). .4fter the plaster has set, the recording for the other side is performed. To remove “premature contacts” between the plaster and the pseudocondyles, corrections are made with a knife. In a second phase the polymethylmethacrylate is introduced into the pseudocondyle cavities. The patient then repeats all of the movements. The instrument is removed from the head and the splints are fit to maxillary and mandibular plaster casts. The classical positions of the centric relation, the protrusive jaiv relation, and the individual lateral movements, as well as a few arbitrary positions are
OOZ-3913/80/080156
+ 05$00.50/08
1980 The C. V. Mosby Co.
ARTICULATOR
RECORDING
TRIDIMENSIONAL
CONDYLE
MOVEMENTS
Fig. 1. Headpiece with lateral receptacles for impression material, to which a maxillary (lower right) can be affixed.
Fig. 2. Face-bow pseudocondyles.
fixed by the splint
to the mandible.
then recorded on the instrument [now the articulator) with wax records. Two pseudocondyle cavities are now formed by the tridimensional movements of the pseudocondyles in the impression material. The walls of these cavities represent the extreme movements of the pseudocondyles. The recorded wax records are then checked in the mouth. This ascertains that the mouth and articulator records are interchangeable.
THE JOURNAL
OF PROSTHETIC
DENTISTRY
Note the ovoid
splint
shape of the
DISCUSSION The proposed tridimensional recording device has the advantage of recording all condylar movements carried out by the mandible. The recording comprises not only the classical measurements such as the centric relation, lateral movements, and protrusive jaw relations, but also all intermediary movements. It increases the likelihood that no unique movement will be omitted.
157
SWEIJD
Fig. 3. Patient in occlusion near centric relation.
Fig. 4. Pseudocondyle in maximally
backward and uppermost position.
Fig. 5. Small opening of the mandible.
158
AUGUST 1980
VOLUME 44
NUMBER 2
ARTICULATOR
RECORDING
TRIDIMENSIONAL
Fig.
CONDYLE
6.
MOVEMENTS
Pseudocondyle in intermediary
Fig. 7. Maximal
position.
opening of the jaws.
Fig. 8. Extreme opening registration.
THE JOURNAL
OF PROSTHETIC
DENTISTRY
159
SWEIJD
SUMMARY
12
A recording
instrument was constructed which also functions as an articulator. It consists of a face-bow with pseudocondyles which forms pseudocondyle cavities in impression material placed laterally from the auditory canals. Occlusal registrations were interchangeable on the articulator and in the mouth. REFERENCES I 2. 3 4 5. 6.
7. 8
9 10.
11.
160
Shanahan. T E. J , and Leff. A : Mandtbular and articulator movements. J PROSTHET DENT 6:941. 1959. Kurth, L. E. Physics of mandibular movement related to full denture construction. J PROSTHET DENT 4:61 I. 1954 Giffen. i*: .4. Registration of mandtbular movements wth plastic material. J Am Dent .4ssoc 14:1480, 1927. Bra\\ n, A H. Movements of the mandible not provided for in present dav articulators. J Am Dent izssoc 17:982. 1930 Needles,J W Mandibular movements and occlusion J Am Dent .4ssmx 14:786, 1927. DiPietro, G. J., and Moergeli, J. R.: Significance of the Frankfort-mandibular plane angle to prosthodontics. J PROSTHET DEYT 36:624, 1976 Borgh. 0. and Posselt, U: Hinge axis registration on articulator J PROWHET DENT 8:35, 1958. Cohen. R.. The hinge axis and its practical application in the determination of crntric relation. J PROSTHET DENT 10:248. 1960. Hughes. G. .4, and Regli, C. P : What is centric relation? J PROSTHI:T DENT 11316, 1961. Boucher. C 0 : Method of recording functIona movements of full-denture bases in three dimensions. J Dent Res 14:39. 1934. Gysi. A.: .4n analysis of the development of the articulator J Am Dent .4ssoc 17:1401, 1930
13. 14. 15.
16.
17.
18.
19. 20.
21.
M’einberg, L. .4.: The occlusal plane and cuspal inclination in relation to incisal condylar guidance for protrusive excursions. J PROSWET DENT 9:6Oi. 1959 Benson, C. W : Condylar guidance. J Am Dent Assoc 19:1591. 1932 Hanau, R L Arttculation defined. analyzed. and formulated. J Am Dent .4ssoc 13:1694, 1926 IYeinberg. L. A : An evaluanon of basic artrculators and thew concepts. Part I Baw concepts. J PROSTHET DENT 13:622. 1963 IVeinberg, L. .4 : An evaluation of basic articulators and their concepts. Part I\’ Fullv adjustable articulators. J PROSTHET DENT 13:1038. 1963. Beck. D. B.. and Knap. F. J.: Reliabilitv of fully adjustable articulators using a computewed analysts J PROSTHET DENT 35:630, 19i6 Finger. I hf.. Foreman. D., and Tanaka, H : Optical method for articulator comparison and Ftudy of occlusal determinants J Dent Res 55:1042, 19i6 Atkinson, H F. Occlusion A mbth or a must. Aust Dent J 21:334. 1967. Hughes, G. A: Discussion of “Factors Influencing centric relation records in edentulous mouths ” J PROSTHET DENT 14:1066, 1964 Yurkstas, A A., and Kapur, K. K: Factors influencing centric relation records in edentulous mouths J PROSTHET DENT 14:1054. 1964
Rejmnt requeststo. DR. F. SWEIJD \‘RIJE UNIVERSITEIT BRUSSEL FNWLTEIT GENEESKUNDE LAARBEEKLAAN 101 1090 BRUSSELS BELGILW
AUGUST
1980
VOLUME
44
NUMBER
2