- Email: [email protected]
Computerized occlusal analysis: An evaluation of the sensors
PROGRAMMINGARTICULATORS.PARTII
versa1jig were disappointing despite remaining within the limits of acceptability. This could be attributed to the expansion of the setting plaster or to a record that is too precise to fit on the casts. Wax is preferred for recording centric relation with the universal jig. Nonetheless, plaster is still recommended for the programming of semiadjustable articulators because the minimal error of 1 or 2 mm resulted in acceptable measurements. In addition, whatever the method, it cannot interfere with the recording of posterior determiners.l The ease of developing the universal jig with prefabrication capabilities encourages construction for each patient. The same jig can be customized for several patients after sterilization.
CONCLUSION
REFERENCES Dupas PH, Dehaine F, Lefevre C, Graux F, Picart B. Proposition dune nouvelle methode de programmation des articulateurs semi-adaptables. Information Dentaire 1985;43:4691-701. Dupas PH, Graux F, Lefevre C, Picart B, Vincent F. Le jig universel. Les Cahiers de Prothese 1987;57:775-25. Delahaye JC. Le jig universe& etude de sa fiabilite, comparaison avec le jig de Lucia sur 10 cas cliniques [Thesis]. LilIe, France: University of Lille, 1987. Clayton JA, Crispin BJ, Shields MJ, Myers GE. A pantographic reproducibility index (PRI) for detection of T.M.J. dysfunction [Abstract]. J Dent Res 1976;55:161. Rosenblum R, Huffman R. Leaf gauge with consecutively numbered leaves. J PROSTHET DENT 1985;54:652-4. Long J. Locating centric relation with a leaf gauge. J PROSTHET DENT 1973;29:608-10.
Macquet P. L’influence de la cinematique dentodentaire sur l’enregistrement des determinants posterieurs [Thesis]. Lille, France: University Lille, 1987.
Reprintrequeststo:
The consistent performances of the universal jig demonstrated reliability, both for recording centric relation and programming semiadjustable articulators. It is recommended that thse dentist use the universal jig to resolve daily occlusal problems because it is effective and uncomplicated.
Computerized
occlusal
analysis:
DR. PIERRE HUBERT DUPAS 5, RUE DU 19 JUIN 1940 59230 SAINT AMAND LES EAUX FRANCE
Contributing author F. Dehaine, D.C.D., Assistant Professor, Department of Prosthetics, Lille University Dental Center, Lille, France
An evaluation
of the sensors
Wayne L. Harvey, D.D.S., M.A.,* Royce A. Hatch, D.D.S., M.S.,** and John W. Osborne, D.D.S., M.S.*** University of Colorado, School of Dentistry, Denver, Colo. Dentists traditionally depend on their experiences to evaluate occlusion. A computerized system, that enables an objective analysis of dental occlusion has been developed and is currently available. A key component of the system is the disposable sensor. This research tested the sensors’ validity and reliability in detection of known interceptive occlusal contact and discovered that the sensors were valid when used just twice. (J PROSTHET DENT 1991;68:89-92.)
T
he T-Scan computerized system (Teksan Inc., Boston, Mass.) that records the location, sequence, and relative force of occlusal contacts recently has been made available to the practicing dentist. The electronic components are a system unit, software, handle with cable, and a disposable sensor (Figs. 1 through 3). When a patient occludes on the thin Y-shaped circuitboard sensor, the dentist can select various modes of operation. The system can register the sequence of each tooth contact by time and location, generate a 3-D force plot of
Supported in part by BSRG No. 2536965and enrichment grant No. 2117301. *Professor, Restorative
Dentistry;
Acting Clinic Director.
**Associate Professsorand Chairman, Restorative Dentistry. ***Professor, Restorative Dentistry; Director of Clinical Research.
10/l/22262 TAEJOURNALOP
PROSTEETIC DENTISTRY
each tooth contact, display a color-coded view of relative forces at each tooth contact; record occlusion in excursions, and produce a permanent record with the self-contained printer.l This research tested the reliability and validity of the latest sensors and established the mean threshold force required to record a known interceptive occlusal contact. The project was designed to repeatedly measure the validity of identical results.
MATERIAL
AND METHODS
A set of Denar No. 118 Goldberg premounted dentate epoxy casts were attached to a Denar Mark II articulator (Denar Corp., Anaheim, Calif.). The casts were selectively equilibrated to possess one known interceptive occlusal contact, by use of occlusal registration strips (Artus Corp., Englewood, N.J.) and articulating ribbon (Denar Corp.) The articulator was locked in the centric position and 89
HARVEY,
SYSTEM
HATCH,
AND
OSBORNE
UNIT PRINTER PORT
POWER SUPPLY I
SENSOR CIRCUIT
COMPUTER MOTHERBOARD
I
I
CONTROL BUTTONS
Fig.
t
Electrically Conductive Columns
Fig.
To
Sensor
1. Schematic diagram of T-Scan system.
Handle
Electrically Conductive ROWS
2. Schematic diagram of sensor.
clamped to the frame of a No. 2 Greenerd Arbor press (Press and Machine Co., Nashua, N.H.) so that the press would apply load to the articulator in the center of the stud bolt holding the upper mounting ring (Fig. 4). Twenty sensors were randomly selected from a stock of 100 sensors. Each new sensor was locked into the handle
90
3. System unit with buttons to select various modes of operation.
Fig.
and centered in the interocclusal position with the handle slightly elevated according to the manufacturer’s instructions. The arm of the press was slowly directed downward, increasing the load at the rate of 0.625 kg/second until the T-Scan instrument visually recorded the first solid-light occlusal contact.
JANUARY
1991
VOLUME
66
NUMBER
1
COMPUTERIZED
OCCLUSAL
ANALYSIS
The threshold force was defined as the minimum load required to produce an occlusal contact. An occlusal contact was defined as a solid, continuous light on the replica of a tooth or teeth on the video screen. An intermittent light was not counted as an occlusal contact. The sensor was removed and then replaced between the teeth. The same procedure was repeated by applying load with the press until the screen responded with an occlusal contact. Three separate recordings were made with each sensor and the data were recorded.
RESULTS The sensor accurately located the occlusal prematurity twice. A third closure indicated additional contacts and needed a greater load to record the electronic response. A mean load of 2.7 kgs (SD 0.92, SE 0.206) was required to signify the threshold contact on the first closure and the mean load for the second and third closures increased to 3 kgs (SD 0.93, SE 0.0206) and 3.8 kgs (SD 0.27, SE 0.208) respectively (Figs. 5 and 6). The ANOVA demonstrated no significant differences (0.05 level) between the first and second interocclusal data. However, the Fisher PLSD and Scheffe F-test computed that there were significant differences (0.05 level) between the first and third and the second and third recordings.
DISCUSSION Dentists analyze the occlusion of patients in various ways.2-10One colmmon approach has a patient close in centric occlusion, a’r the intercuspal position, on a marking medium or wax to identify the location of occlusal contact(s). The sensitivity and accuracy of the marking medium is critical because the identification of interceptive occlusal contacts is essential for the diagnosis and treatment of occlusal problems. If the identification of the occlusal contacts is inappropriate because of a poor marking system or an interocclusal record requiring an inordinate amount of force, the dentist will be misled. Some indicating media can consistently transfer marks on teeth on the surface of the true contact(s) but do not identify the exact teeth striking prematurely. Therefore, the indicator is not an accurate indicator of occlusion.ll The force a patient generates on an indicator for an effective recording is also crucial. For example, when a marking system requires excessive force to indicate occlusal contacts, an error can be produced by either causing a mechanical deflection of the mandible or by activating the patient’s protective musculature reflex, which diverts the mandible from the deflective contact. Unfortunately, the various devices for locating deflective contacts require subjective interpretation by a dentist. The veracity of the interpretations increases with knowledge, patient manipulative skills, and the reliability of the
THE
JOURNAL
Ol? PROSTHETIC
DENTISTRY
Fig. 4. Denar articulator C-clamped to base of Greenerd press. marking medium. For recording a maxillomandibular occlusal relationship, the challenge has been to determine the timing and specific location of the occlusion. If excessive masticatory forces were suspected, the dentist regulated the force on the teeth by noting abnormal wear facets, tooth mobility, tissue color, and contour. In addition, dentists commonly gain experience by using a variety of occlusal indicator materials to develop confidence in a specific procedure. Future research is indicated to verify the validity and reliability of the T-scan sensor of known occlusal contacts when fully equilibrated dentate casts are analyzed.
SUMMARY This study established the threshold force required to record an electronic occlusal contact using a T-Scan sensor. The validity and reliability were tested by measuring the sensors’ ability to replicate results, The sensors were reliable and valid within a range of threshold forces of 2.7 kg to 3 kg if applied only twice to the individual sensor. A third application of force to the same sensor produced a statistically significant difference in the sensor.
91
HARVEY,
ldu&
atdupr
HATCH,
AND
OSBORNE
3r.m
Fig. 5. Mean bars of threshold values computed with 20 sensors from three separate occlusal registrations.
Fig. 6. Mean bars and one standard deviation error bar generated by three occlusal recordings with 20 sensors.
CONCLUSIONS
4. Berry D, Singh B. Daily variations in occlusal contacts. J PROSTHET
The single interceptive occlusal contact, created for this project, was accurately identified and recorded by the T-Scan after two closures. Therefore, the sensors were valid and reliable when used twice. The data suggested that the dentist should register only two interocclusal records with each sensor because the third recording was not accurate.
5. Berry D, Singh B. Effect of electromyographic biofeedback therapy on occlusal contacts. J PROSTHET DENT 1987;51:397-403. 6. Dawson P, Arcan M. Attaining harmonic occlusion through visualized strain analysis. J PROSTHET DENT 1981;46:615-22. 7. Tryde G, Frydenberg 0, Brill N. An assessment of the tactile sensibility in human teeth: an evaluation of a qualitative method. Acta Odonto1 Stand 1961;20:233-56. 8. Riise C. A clinical study of the number of occlusal tooth contacts in the intercuspal position at light and hard pressure in adults. J Oral Rehabil 1982;9:469. 9. Troest T. Diagnosing minute deflective occlusal contacts. J PROSTHET
We thank Dr. Leon Silverstone, Associate Dean for Research, at the University of Colorado School of Dentistry for his support.
DENT 1964;14:71-3. 10. Weinberg L. Rationale and technique for occlusal equilibration. J PROSTHET DENT 1964;14:74-86. 11. Gazit E, Fitzig S, Lieberman M. Reproducibility of occlusal marking techniques. J PROSTHET DENT 1986;55:505-9.
REFERENCES 1. Maness WL, Benjamin M, Podoloff R, et al. Computerized occlusal analysis: a new technology. Quintessence Int 1987;18:287-92. 2. Millstein PL. An evaluation of occlusal contact marking indicators: a descriptive, qualitative method. Quintessence Int 1983;14:813-36. 3. Ehrlich J, Taicher S. Intercuspal contacts of the natural dentition in centric occlusion. J PROSTHET DENT 1981;45:419-21.
92
DENT 1983;50:366-91.
Reprint requeststo: DR. WAYNE L. HARVEY SCHOOL OF DENTISTRY, C-284 UNIVERSITY OF COLORADO 4200 E. NINTH AVE. DENVER, CO 80262
JANUARY
1991
VOLUME
66
NUMBER
1
versa1jig were disappointing despite remaining within the limits of acceptability. This could be attributed to the expansion of the setting plaster or to a record that is too precise to fit on the casts. Wax is preferred for recording centric relation with the universal jig. Nonetheless, plaster is still recommended for the programming of semiadjustable articulators because the minimal error of 1 or 2 mm resulted in acceptable measurements. In addition, whatever the method, it cannot interfere with the recording of posterior determiners.l The ease of developing the universal jig with prefabrication capabilities encourages construction for each patient. The same jig can be customized for several patients after sterilization.
CONCLUSION
REFERENCES Dupas PH, Dehaine F, Lefevre C, Graux F, Picart B. Proposition dune nouvelle methode de programmation des articulateurs semi-adaptables. Information Dentaire 1985;43:4691-701. Dupas PH, Graux F, Lefevre C, Picart B, Vincent F. Le jig universel. Les Cahiers de Prothese 1987;57:775-25. Delahaye JC. Le jig universe& etude de sa fiabilite, comparaison avec le jig de Lucia sur 10 cas cliniques [Thesis]. LilIe, France: University of Lille, 1987. Clayton JA, Crispin BJ, Shields MJ, Myers GE. A pantographic reproducibility index (PRI) for detection of T.M.J. dysfunction [Abstract]. J Dent Res 1976;55:161. Rosenblum R, Huffman R. Leaf gauge with consecutively numbered leaves. J PROSTHET DENT 1985;54:652-4. Long J. Locating centric relation with a leaf gauge. J PROSTHET DENT 1973;29:608-10.
Macquet P. L’influence de la cinematique dentodentaire sur l’enregistrement des determinants posterieurs [Thesis]. Lille, France: University Lille, 1987.
Reprintrequeststo:
The consistent performances of the universal jig demonstrated reliability, both for recording centric relation and programming semiadjustable articulators. It is recommended that thse dentist use the universal jig to resolve daily occlusal problems because it is effective and uncomplicated.
Computerized
occlusal
analysis:
DR. PIERRE HUBERT DUPAS 5, RUE DU 19 JUIN 1940 59230 SAINT AMAND LES EAUX FRANCE
Contributing author F. Dehaine, D.C.D., Assistant Professor, Department of Prosthetics, Lille University Dental Center, Lille, France
An evaluation
of the sensors
Wayne L. Harvey, D.D.S., M.A.,* Royce A. Hatch, D.D.S., M.S.,** and John W. Osborne, D.D.S., M.S.*** University of Colorado, School of Dentistry, Denver, Colo. Dentists traditionally depend on their experiences to evaluate occlusion. A computerized system, that enables an objective analysis of dental occlusion has been developed and is currently available. A key component of the system is the disposable sensor. This research tested the sensors’ validity and reliability in detection of known interceptive occlusal contact and discovered that the sensors were valid when used just twice. (J PROSTHET DENT 1991;68:89-92.)
T
he T-Scan computerized system (Teksan Inc., Boston, Mass.) that records the location, sequence, and relative force of occlusal contacts recently has been made available to the practicing dentist. The electronic components are a system unit, software, handle with cable, and a disposable sensor (Figs. 1 through 3). When a patient occludes on the thin Y-shaped circuitboard sensor, the dentist can select various modes of operation. The system can register the sequence of each tooth contact by time and location, generate a 3-D force plot of
Supported in part by BSRG No. 2536965and enrichment grant No. 2117301. *Professor, Restorative
Dentistry;
Acting Clinic Director.
**Associate Professsorand Chairman, Restorative Dentistry. ***Professor, Restorative Dentistry; Director of Clinical Research.
10/l/22262 TAEJOURNALOP
PROSTEETIC DENTISTRY
each tooth contact, display a color-coded view of relative forces at each tooth contact; record occlusion in excursions, and produce a permanent record with the self-contained printer.l This research tested the reliability and validity of the latest sensors and established the mean threshold force required to record a known interceptive occlusal contact. The project was designed to repeatedly measure the validity of identical results.
MATERIAL
AND METHODS
A set of Denar No. 118 Goldberg premounted dentate epoxy casts were attached to a Denar Mark II articulator (Denar Corp., Anaheim, Calif.). The casts were selectively equilibrated to possess one known interceptive occlusal contact, by use of occlusal registration strips (Artus Corp., Englewood, N.J.) and articulating ribbon (Denar Corp.) The articulator was locked in the centric position and 89
HARVEY,
SYSTEM
HATCH,
AND
OSBORNE
UNIT PRINTER PORT
POWER SUPPLY I
SENSOR CIRCUIT
COMPUTER MOTHERBOARD
I
I
CONTROL BUTTONS
Fig.
t
Electrically Conductive Columns
Fig.
To
Sensor
1. Schematic diagram of T-Scan system.
Handle
Electrically Conductive ROWS
2. Schematic diagram of sensor.
clamped to the frame of a No. 2 Greenerd Arbor press (Press and Machine Co., Nashua, N.H.) so that the press would apply load to the articulator in the center of the stud bolt holding the upper mounting ring (Fig. 4). Twenty sensors were randomly selected from a stock of 100 sensors. Each new sensor was locked into the handle
90
3. System unit with buttons to select various modes of operation.
Fig.
and centered in the interocclusal position with the handle slightly elevated according to the manufacturer’s instructions. The arm of the press was slowly directed downward, increasing the load at the rate of 0.625 kg/second until the T-Scan instrument visually recorded the first solid-light occlusal contact.
JANUARY
1991
VOLUME
66
NUMBER
1
COMPUTERIZED
OCCLUSAL
ANALYSIS
The threshold force was defined as the minimum load required to produce an occlusal contact. An occlusal contact was defined as a solid, continuous light on the replica of a tooth or teeth on the video screen. An intermittent light was not counted as an occlusal contact. The sensor was removed and then replaced between the teeth. The same procedure was repeated by applying load with the press until the screen responded with an occlusal contact. Three separate recordings were made with each sensor and the data were recorded.
RESULTS The sensor accurately located the occlusal prematurity twice. A third closure indicated additional contacts and needed a greater load to record the electronic response. A mean load of 2.7 kgs (SD 0.92, SE 0.206) was required to signify the threshold contact on the first closure and the mean load for the second and third closures increased to 3 kgs (SD 0.93, SE 0.0206) and 3.8 kgs (SD 0.27, SE 0.208) respectively (Figs. 5 and 6). The ANOVA demonstrated no significant differences (0.05 level) between the first and second interocclusal data. However, the Fisher PLSD and Scheffe F-test computed that there were significant differences (0.05 level) between the first and third and the second and third recordings.
DISCUSSION Dentists analyze the occlusion of patients in various ways.2-10One colmmon approach has a patient close in centric occlusion, a’r the intercuspal position, on a marking medium or wax to identify the location of occlusal contact(s). The sensitivity and accuracy of the marking medium is critical because the identification of interceptive occlusal contacts is essential for the diagnosis and treatment of occlusal problems. If the identification of the occlusal contacts is inappropriate because of a poor marking system or an interocclusal record requiring an inordinate amount of force, the dentist will be misled. Some indicating media can consistently transfer marks on teeth on the surface of the true contact(s) but do not identify the exact teeth striking prematurely. Therefore, the indicator is not an accurate indicator of occlusion.ll The force a patient generates on an indicator for an effective recording is also crucial. For example, when a marking system requires excessive force to indicate occlusal contacts, an error can be produced by either causing a mechanical deflection of the mandible or by activating the patient’s protective musculature reflex, which diverts the mandible from the deflective contact. Unfortunately, the various devices for locating deflective contacts require subjective interpretation by a dentist. The veracity of the interpretations increases with knowledge, patient manipulative skills, and the reliability of the
THE
JOURNAL
Ol? PROSTHETIC
DENTISTRY
Fig. 4. Denar articulator C-clamped to base of Greenerd press. marking medium. For recording a maxillomandibular occlusal relationship, the challenge has been to determine the timing and specific location of the occlusion. If excessive masticatory forces were suspected, the dentist regulated the force on the teeth by noting abnormal wear facets, tooth mobility, tissue color, and contour. In addition, dentists commonly gain experience by using a variety of occlusal indicator materials to develop confidence in a specific procedure. Future research is indicated to verify the validity and reliability of the T-scan sensor of known occlusal contacts when fully equilibrated dentate casts are analyzed.
SUMMARY This study established the threshold force required to record an electronic occlusal contact using a T-Scan sensor. The validity and reliability were tested by measuring the sensors’ ability to replicate results, The sensors were reliable and valid within a range of threshold forces of 2.7 kg to 3 kg if applied only twice to the individual sensor. A third application of force to the same sensor produced a statistically significant difference in the sensor.
91
HARVEY,
ldu&
atdupr
HATCH,
AND
OSBORNE
3r.m
Fig. 5. Mean bars of threshold values computed with 20 sensors from three separate occlusal registrations.
Fig. 6. Mean bars and one standard deviation error bar generated by three occlusal recordings with 20 sensors.
CONCLUSIONS
4. Berry D, Singh B. Daily variations in occlusal contacts. J PROSTHET
The single interceptive occlusal contact, created for this project, was accurately identified and recorded by the T-Scan after two closures. Therefore, the sensors were valid and reliable when used twice. The data suggested that the dentist should register only two interocclusal records with each sensor because the third recording was not accurate.
5. Berry D, Singh B. Effect of electromyographic biofeedback therapy on occlusal contacts. J PROSTHET DENT 1987;51:397-403. 6. Dawson P, Arcan M. Attaining harmonic occlusion through visualized strain analysis. J PROSTHET DENT 1981;46:615-22. 7. Tryde G, Frydenberg 0, Brill N. An assessment of the tactile sensibility in human teeth: an evaluation of a qualitative method. Acta Odonto1 Stand 1961;20:233-56. 8. Riise C. A clinical study of the number of occlusal tooth contacts in the intercuspal position at light and hard pressure in adults. J Oral Rehabil 1982;9:469. 9. Troest T. Diagnosing minute deflective occlusal contacts. J PROSTHET
We thank Dr. Leon Silverstone, Associate Dean for Research, at the University of Colorado School of Dentistry for his support.
DENT 1964;14:71-3. 10. Weinberg L. Rationale and technique for occlusal equilibration. J PROSTHET DENT 1964;14:74-86. 11. Gazit E, Fitzig S, Lieberman M. Reproducibility of occlusal marking techniques. J PROSTHET DENT 1986;55:505-9.
REFERENCES 1. Maness WL, Benjamin M, Podoloff R, et al. Computerized occlusal analysis: a new technology. Quintessence Int 1987;18:287-92. 2. Millstein PL. An evaluation of occlusal contact marking indicators: a descriptive, qualitative method. Quintessence Int 1983;14:813-36. 3. Ehrlich J, Taicher S. Intercuspal contacts of the natural dentition in centric occlusion. J PROSTHET DENT 1981;45:419-21.
92
DENT 1983;50:366-91.
Reprint requeststo: DR. WAYNE L. HARVEY SCHOOL OF DENTISTRY, C-284 UNIVERSITY OF COLORADO 4200 E. NINTH AVE. DENVER, CO 80262
JANUARY
1991
VOLUME
66
NUMBER
1