A Comparative Evaluation to Measure the Sagittal Condylar Guidance Values Between the Semiadjustable Articulators and Radiographic Images
Fahad H. Banasr - BDS, Ms, DSCD
Associate Professor, Department of Oral & Maxilofacial Prosthodontics, Division of Removable Prosthodontics, King Abdulaziz University
Kingdom of Saudi Arabia
Lana A. Shinawi - BDS, KSU, MSc, MCD, PhD (UCL)
Associate Professor and Consultantof Prosthodontics. Department of Oral & Maxilofacial Prosthodontics, Division of Removable Prosthodontics, King Abdulaziz University | Kingdom of Saudi Arabia
Ingy Said A. Soliman - BDS, MSc
Assistant Lecturer, Department of Removable Prosthodontics, Alexandria University | Egypt
Eman M. Al-Rafah - BDS, MSc, PhD
Professor in Prosthodontics, Department of Oral & Maxillofacial Prosthodontics, Division of Removable Prosthodontics, King Abdulaziz University, Kingdom of Saudi Arabia | firstname.lastname@example.org
Zainab Abdelsalam - BDS, MSc, PhD
Professor, Oral & Maxillofacial Radiology, King Abdulaziz University | Kingdom of Saudi Arabia
The purpose of this study was to compare the sagittal condylar guidance values clinically between arcon and non arcon semiadjustable articulators from Hanau type and panoramic readings. The clinical method of measuring the sagittal condylar guidance value was made using the same protrusive record made with edge to edge degree of protrusion through using a custom-made duralay acrylic resin jig for twenty complete dentate healthy subjects. The interocclusal protrusive records were transferred to the Hanau articulators to programming them. Digital Orthopantomographic (OPG) was taken for all the subjects and the condylar guidance values were recorded for right and left sides and tabulated. The results were subjected to statistical analysis with a significance level of p<0.05.The results showed statistically significant difference between the mean sagittal guidance values obtained from arcon and non arcon methods. Also there was no significant difference between the mean sagittal condylar guidance values obtained from arcon and panoramic tracing methods. A significant positive correlation existed in the sagittal congylar guidance mean values between arcon method and panoramic tracing on the right and left sides. The results of this study indicate that the sagittal condylar guidance values obtained from panoramic radiographic tracings may be of value as an aid in programming the condylar guidance in semiadjustable articulators to obtain clinically acceptable restorations.
Protrusive interocclusal recording materials, Semiadjustable articulators, Protrusive condylar guidance, Panoramic radiograph.
Articulators are mechanical devices which can accurately simulate the mandibular movements, and are used in diagnostic and therapeutic purposes.1,2 In clinical practice, we most frequently use them in fabrication of removable and fixed dentures. Occlusal adjustments of occlusal surfaces, especially at fixed dentures, can be time consuming, difficult and sometimes frustrating.3
Many practitioners rely on average values of condylar guidance, which range from 220 to 650.4,5 If the individual inclination of the articular eminence is very steep or flat, guidance obtained from the average value settings may differ sufficiently to cause problems such as posterior disocclusion or balanced occlusion.6,7
Accurate simulation of mandibular movements enables the fabrication of prosthetic restoration with occlusal surfaces i.e. cusps height and inclination which are compatible with the condylar guidance.8-10 Prosthetic restoration fabricated in such a way will require minimal intraoral adjustment, and will therefore have completely preserved occlusal surfaces.11
When the casts are mounted in a semiadjustable articulator by use of facebow, and an individually adjusted condylar guidance by intraoral records or extraoral method, a close approximation of mandibular movements can be obtained.11-13 The most frequently used method is the articulator individualization by eccentric interocclusal records.14-16 This procedure is simple, quick, and applicable in daily clinical practice. The accuracy of the articulator adjustment depends upon the choice of material used for records, the method of procedure and the skill of the therapist.1,3,17
The different materials used as interocclusal recording medium to obtain centric, protrusive and lateral interocclusal records are Plaster of Paris, wax, modeling compound, acrylic resin, zinc oxide paste and elastomers. The protrusive interocclusal record is required for setting the horizontal condylar inclination in the articulator.18-21
Comparative studies using interocclusal recording materials to record horizontal condylar inclination (HCI) have shown that selection of the material is an important factor to be considered. Most of these interocclusal recording materials were shown having varying degrees of reproducibility of condylar inclinations when used along with different semiadjustable articulators.22-24
Condylar guidance can also be recorded from radiographs which involve stable bony landmarks and can be standardized. Literature indicates the use of lateral cephalograms, pantomographs, tomographs, digital CT scans and electronic axiography for recording condylar guidance.6,25,26
Studies have shown that radiographic methods can record condylar guidance more accurately than other methods even though the expense, inconvenience and radiation exposure which deterrents the widespread usage.27 Panoramic radiography is widely used for diagnosis, also it can be used in setting the condylar guidance inclination in semiadjustable articulator.6
Since both types of semiadjustable articulators (arcon and nonarcon) are widely used in daily practice, this clinical study is to analyze the discrepancy between condylar guidance angles obtained from these two articulators using same protrusive interocclusal records and comparing them with the values made using orthopantomographic (OPG) tracings.
MATERIALS & METHODS
Following ethical approval, that was granted by Ethical Committee at King Abdulaziz University Dental Hospital. Each subject gave her/his written informed consent for participating in this study. Twenty complete dentate healthy subjects were enrolled from Dental prosthodontics clinics, faculty of dentistry, King Abdulaziz University Dental Hospital and faculty of dentistry, Alexandria University in the age group of 21-35 years old. The inclusion criteria were the presence of angle’s class one molar relationship with no spacing or crowding of anterior teeth. The presence or absence of the third molar was not considered. Subjects with signs & symptoms of Temporomandibular joint dysfunction, any kind of prosthesis or history of orthodontic treatment, poor neuromuscular co-ordination were excluded.
Two impressions for each jaw were taken from each subject by commercial trays and irreversible hydrocolloid material (Tropicalgin, chromatic Alginate, Zhermach, Italy) & were poured immediately using dental stone giving two sets of maxillary & mandibular casts for each subject.
The upper jaw casts were mounted into upper parts of both types of the articulators (Hanau wide-vue arcon and Hanau H2 nonarcon type) by using their facebows (fig. 1A). Casts of lower jaw were mounted to the upper ones of both articulators by same centric interocclusal record (fig. 1B) (Virtual CAD bite registration addition-reaction silicone Ivoclar Vivadent, Inc, USA).
The subjects were prepared for making the protrusive interocclusal record by instructing them to practice the movement of the mandible forward and backward. A custom-made duralay acrylic resin anterior contact device (Ostron100TM, Japan) that attached to the labial surface of the maxillary anterior teeth was made to allow the subject to move the mandible exactly the same edge to edge protrusive relationship and eliminates the risk of mandibular deviation while injecting the registration material. The protrusive interocclusal record was made in edge to edge relationship at 6mm protrusion by using Virtual CAD bite registration addition reaction silicone (ivoclar vivadent, Inc, USA).
This protrusive record was used to program both articulators. The adjustment of sagittal condylar guidance values were recorded for each articulator on the right and left side (fig. 1C). In all the cases, articulator was programmed by a single operator.
The radiographic procedures were carried out in Oral Radiology department, faculty of dentistry at king Abdulaziz University. Digital OPG image was made for all subjects with the Frankfurt horizontal plane parallel to the floor of the mouth by the same single operator with the same panoramic radiographic OPG machine (Sordex, Gendex, Finland). The images were acquired with exposure factors of 90-57 KVp and 14s Ma. Tracing of the radiographic image were made for the right and left sides. A horizontal line was marked by joining the “Orbitale” (lower point in the margin of the orbit) and “Porion” (highest point in the margin of the auditory meatus). A second line was marked by joining the most superior point on the articular eminence and the most inferior point on the articular fossa of the temporal bone. The angle formed by the intersection of the two lines was determined to represent the angle of sagittal condylar inclination. (fig. 2)
The data readings consisted of three values of the sagittal condylar guidance obtained from sixteen subjects under investigation throughout programming each joint of the two types articulator used and the sagittal condylar guidance obtained from the OPG tracing were tabulated.
The data was subjected to paired t-test for comparison between the three methods. Pearson’s correlation test was used to correlate the different methods used to measure the sagittal condylar guidance values for both joint.
Table 1 showed the obtained mean values of right and left protrusive condylar inclination for Hanau wide-vue (arcon) and Hanau H2 (nonarcon) articulators and digital OPG tracing. The values were obtained by setting both articulators with the same protrusive record to produce the same amount of protrusive movement in both articulators for each subject.
The mean value and standard deviation of the sagittal condylar guidance values on right and left side respectively for 20 subjects obtained by Hanau wide-vue, Hanau H2 and OPG tracings were 35.38±5.14 degrees, 29.87± 3.83 degrees, 35.25±4.25 degrees on the right side and 35.06±6.08 degrees, 30.50± 4.68 degrees, 34.06± 4.58 degrees on the left side.
Also table1 showed the mean difference in sagittal condylar guidance values on the right side and left side respectively. By comparing the mean difference in sagittal condylar guidance values between Hanau wide-vue and OPG tracing, there was no significant difference found on the right and left sides respectively (P1) 0.858 and 0.112.
The mean difference in sagittal condylar guidance values between Hanau H2 (non arcon) and OPG tracing was found to be statistically significant on the right and left sides respectively (P2) 0.001 and 0.001. Also there was statistical significant difference in the mean sagittal condylar guidance values was found between Hanau wide-vue (arcon) and Hanau H2 (non arcon) on the right and left sides respectively (P3) 0.001 and 0.001.
Table 2 Showed inter comparison of mean sagittal condylar guidance values obtained from the three different methods. There was positive correlation coefficient in the sagittal condylar guidance mean values between Hanau wide-vue and OPG tracing for the right side(r) 0.838 and left side(r) 0.893 which was statistically significant P≤ 0.05.
Table 3 showed the distribution of differences in values of condylar inclination between the three different methods in the right and left side condyle. All readings of sagittal condylar guidance values of the right side showed a difference <4 degree (100%) between Hanau wide-vue (arcon) and OPG tracing, while the same difference was observed in 31.3% for Hanau H2 (nonarcon) and OPG tracing combination, and 37.5% for Hanau wide-vue and Hanau H2 combination.
Also all readings of sagittal condylar guidance values of the left side showed a difference <4 degree (100%) between Hanau wide-vue (arcon) and OPG tracing, while the same difference was observed in 37.5% for Hanau H2 (nonarcon) and OPG tracing combination, and 25.0% for Hanau wide-vue and Hanau H2 combination.
Semiadjustable articulators are commonly used in prosthodontics For their simplicity in handling and programming28 to customize the condylar angulations and settings to simulate the movements of the temporomandibular joint of the patient.13,16,29
The plane of reference during measuring the condylar inclination is a relevant parameter to consider, because condylar inclination values cannot be compared when obtained with different planes of reference.6,10,25
The semiadjustable articulators used in this study were Hanau wide-vue (arcon) and Hanau H2 (nonarcon) with their face bows. Both articulators were designed to use the orbitale as anterior reference point for orientation of the maxillary cast which gives three plane position of maxillary cast on both articulator and eliminate the error induced by facebow registration.
A study was made to evaluate the effect of three different anterior points of reference for two different designs of the Hanau articulators (arcon and nonarcon) on protrusive condylar angulation. The study concluded that the casts were significantly closer to the anatomic position whenever orbitale was used as the third point of reference for mounting the cast to the articulator irrespective of type of articulator.30
Weinberg31 evaluated that the various anterior points of reference used in different facebows and concluded that it may raise or lower the occlusal plane by ±16mm and that has no effect on centric occlusion, however it does have an effect on eccentric condylar readings that may influence cuspal inclines.
Gonzalez and Kingery32 claimed that the axis orbital plane is the least variable and more reliable and considered best for facebow registration as it is easy to locate and reproducible.
Because the horizontal condylar guidance changes with the degree of protrusion, so in the present study it was important to keep the distance of protrusion the same for both the articulators during registration of protrusive interocclusal records through the use of the custom-made anterior jig.
Posselt et al.33 reported that correlation exists between degree of protrusion that can influence the setting of condylar readings.
Craddock34 also believed that it was important to keep the distance of protrusion the same because the sagittal condylar angle changes with the amount of protrusion.
In our study, the intraoral method of recording sagittal condylar guidance was used because it is easy and quick method usually applied in daily clinical practice. The protrusive interocclusal record was made in edge to edge relationship by additional polyvinyle siloxane bite registration material to set sagittal condylar guidance on both articulators. The selection of polyvinyle siloxane material for intra-oral record due to its dimensional stability and high accuracy.35
Some authors reported that, selection of materials for intraoral records proved to be very important factor in the transfer procedure. A number of materials are used for records as wax, plaster, ZOË paste, acrylic resins and elastomeres. Wax is the most common material in daily use proved to be the least precise due to high thermal expansion coefficient and big deformations under compression.19,36,37,38 Additional silicones from elastomers proved to be the most precise due to their dimension stability.1,39,40 Also polyvinyl siloxane was found to be reliable recording material because it exhibited the greatest resistance to compression35,36 and produced lowest vertical discrepancy in mounted casts with greatest by wax.22,41
The result of this study revealed significant difference in the mean sagittal condylar guidance values obtained from arcon and nonarcon articulators and also between nonarcon articulator and OPG images on the right and left sides. This finding may be due to that the condylar inclination in arcon articulators remains constant in relation to the maxillary occlusal plane at any degree of opening of the articulator, while in nonarcon articulators, the condylar inclination changes in relation to maxillary occlusal plane at any degree of opening of the articulator.
Also the OPG image reproduces the actual form and angles of the osseous structure of the temporomandibular joint. The current study traced the articular eminence inclination in the radiographic image from the most superior to the most inferior points of curvature and this may be different from guiding inclination of protrusion by clinical interocclusal record.
The result is in accordance with the studies done by Shillingburg et al.42 and Rosensteil et al.15 who stated that the non arcon design condylar inclination of the mechanical fossae changes in relation to the maxillary occlusion plane as the articulator is opened and can lead to errors when a protrusive record of certain thickness is being used to program the articulator. They reported that with 3-5mm thickness of interocclusal record there would be a difference of 80 between where the articulator settings are adjusted and a closed position where the articulator is used.
While comparing the mean difference of sagittal condylar guidance values obtained from arcon articulator and panoramic readings on the right and left sides, the result of these values were statistically not significant. Also there was positive correlation coefficient in the sagittal condylar guidance mean values between Hanau wide-vue and panoramic images. This result may be due to the constant relation between occlusal plane and mechanical fossa reproduces the movements more accurately so the movements are identical to those of natural joint. This anatomic duplication of the temporomandibular joint on the instrument may be responsible for near accurate replication of mandibular movements.
Our results are in agreement with some authors who found that when comparing the mean difference of sagittal condylar guidance values obtained from arcon articulator and cephalometric readings, there was statistically insignificant.14
Our results also in accordance with Corbett et al.43 who studied the condylar movements and confirmed that in protrusion, the condylar head can follows accurately the anatomical form of the articular eminence and represents a very high correlation coefficient and level of significance.
These results supported by Gilboa et al.6 who reported a high degree of correlation between articular morphology and panoramic image and suggested that the inclination of the articular eminence in a panoramic image may be of value in setting the condylar guidance in semiadjustable articulators.
Finally, the results of this study showed the distribution of difference between all methods used for recording sagittal condylar guidance values. The difference in values was observed in all readings 100% less than 40 between arcon articulator and panoramic image while the same difference was observed in 31.3% for Hanau H2 articulator and panoramic image combination and 37.5% for arcon and nonarcon combination. The distribution of difference of sagittal condylar guidance readings showed a high level of reproducibility (strong degree of correlation) determined by Hanau Wide-vue articulator and panoramic tracings and this could be due to the anatomic representation of the articulator design in close approximation with the human temporomandibular joints. Moreover, the panoramic tracings may be made relative to a suitable horizontal reference plane like the Frankfurt horizontal plane.
The result of this study is in agreement with some authors who reported that the panoramic radiograph is extremely useful for comparison between right and left sides since it shows both the TMJs with relatively same magnification errors (x1.2). It is a reproducible radiograph unlike the other TMJ specific radiographs which are subject to projection errors.44
Also digital panoramic imaging has benefits of high quality image, low radiation dosage, direct analysis and reveals accurate morphology of the anatomic landmarks to draw reference planes may be of value in programming the semiadjustable articulator.17,45
Studies by Prajapati P et al.30 provided that the accurate condylar guidance is dependent on the type of the third point of reference point used to mount the maxillary cast on the articulator and there was no significant difference was observed between the Arcon and Non-Arcon types of articulator. They concluded that the orbitale was the accurate third point of reference used to mount the maxillary cast with Arcon articulator.
The results obtained in this study lead to the following conclusions:
1. The arcon type semiadjustable articulator due to constant relation between occlusal plane and mechanical fossa reproduces the movements more accurately.
2. The mean difference of sagittal condylar guidance values obtained using the interocclusal protrusive record in both Arcon and Non-Arcon semiadjustable articulators were found to be statistically significant indicating low level of reproducibility. On the other hand, comparative evaluation of the mean sagittal condylar guidance values obtained from Hanau wide-vue articulator and panoramic tracing showed no significant difference.
3. The type of panoramic radiographic image used for this study is available for bulk of dentists in their clinics and the tracing may be made relative to a suitable horizontal reference plane like the Frankfurt horizontal plane.
4. The tracing of the panoramic image may be used to provide an indication of the degree of inclination of the articular eminence and fossa and may be of value as an aid insetting the condylar guidance in semiadjustable articulators to obtain clinically acceptable restorations.
5. The correlation between mean sagittal readings of Hanau wide-vue articulator and panoramic reading could be possibly due to the anatomic representation of the articulator design in close approximation with the human temporomandibular joint.
1. Campos AA, Nathanson D. Compressibility of two polyvinyl siloxane interocclusal record materials and its effect on mounted cast relationships. J Prosthet Dent. 1999;82(4):456-61.
2. Zabarovic D, Vojvodic D, Katanec D, Jerolimov V, Carek V, Vusic J. Comparative study of condylar inclination settings in two types of semiadjustable articulators. Coll. Antropol. 2009;33(2):431-5.
3. Pelletier LB, Campbell SD. Comparison of condylar control settings using three methods: A bench study. J Prosthet Dent. 1991;66(2):193-200.
4. Aull AE. Condylar determinants of occlusal patterns. J Prosthet Dent. 1965;15:826-49.
5. Payne JA. Condylar determinants in a patient population: Electronic pantographic assessment. J Oral Rehabil. 1997;24:157-63.
6. Gilboa I, Cardash HS, Kaffe I, Gross MD. Condylar guidance: Correlation between articular morphology and panoramic radiographic images in dry human skulls. J Prosthet Dent. 2008;99:477-82.
7. Posselt U, Nevstedt P. Registration of the condyle path inclination by intra-oral wax records- Its practical value. J Prosthet Dent. 1961;1:43-7.
8. Venkateshwaran R, karthigeyan S, Manoharan PS, Konchada J, Ramaswamy M. A newer technique to program a semiadjustable articulator. J Pharmacy and Bioallied Sciences. 2014;6(1):135-9.
9. Michalakis K X,Pissiotis A, Anastasiadou V, Kapari D. An experimental study on particular physical properties of several interocclusal recording media. Part 1: Consistency prior to setting. J Prosthodont. 2004;13(1):42-6.
10. Zamacona JM, Otaduy E, Aranda E. Study of the sagittal condylar path in edentulous patients. J prosthet Dent. 1992;68:314-7.
11. Celenza FV. An analysis of articulators. Dent Clin North Am. 1979;23(2):305-26.
12. Donegan SJ, Christensen LV. Sagittal condylar guidance as determined by protrusion records and wear facets of teeth. Int J Prosthodont. 1991;4(5):469-72.
13. Sharma LA, Azhagarasan NS, Sharma A. Comparative study of the effect of three different interocclusal recording materials on reproducibility of horizontal condylar registrations in two different semiadjustable articulators: A clinical study. International J Prosthodontics and Restorative Dentistry. 2011;1(3):155-62.
14. Goyal MK, Goyal S. A comparative study to evaluate the discrepancy in condylar guidance values between two commercially available arcon and non-arcon articulators: A clinical study. Indian J dental Research. 2011;22(6):880-6.
15. Rosenstiel SF, Land MF, Fujimoto J. Contemporary fixed prosthodontics. 4th ed. St. Louis: Mosby;2006. P.71.
16. Zarb GA, Bolender CL, Eckert SE, Fenton AH, Jacob RF, Mericske-Stern R. Prosthodontic treatment for edentulous patients: complete dentures and implant-supported prostheses. 12th ed. St. Louis:Mosby; 2004.p.294.
17. Tannamala PK, Pulagam M, Pottem SR, Swapna B. Condylar guidance: Correlation between protrusive interocclusal record and panoramic radiographic image. J of Prosthodontics. 2012;21:181-4.
18. Celar AG, Tamaki K, Nitsche S, Schneider B. Guided versus unguided mandibular movement for duplicating intraoral eccentric tooth contacts in the articulator. J Prosthet Dent. 1999;81(1):14-22.
19. Gross M, Nemcovsky C, Tabibian Y, Gazit E. The effect of three different recording materials on the reproducibility of condylar guidance registrations in three semiadjustable articulators. J Oral Rehabil. 1998;25(3):204-8.
20. Gross M, Nemcovsky C, Friedlander LD. Comparative study of condylar settings of three semiadjustable articulators. Int J Prosthodont. 1990;3:135-41.
21. Dos Santos J Jr, Nelson S, Nowlin T. Comparison of condylar guidance setting obtained from a wax record versus an extraoral tracing: a pilot study. J Prosthet Dent. 2003;89:54-9.
22. Fattore L, Malone WF, Sandrick JL, et al. Clinical evaluation of the accuracy of interocclusal records. J Prosthet Dent. 1984;51:152-7.
23. Michalakis KX, Pissiotis A, Anastasiadou V, Kapari D. An experimental study on particular physical properties of several interocclusal recording media. Part III: Resistance to compression after setting. J Prosthodont. 2004;13(3):233-7.
24. Millstein PL, Clark RE, Kronman JH. Determination of the accuracy of wax interocclusal registrations. J Prosthet Dent. 1973;29:40-5.
25. Dos Santos J Jr, Nelson SJ, Nummikoski P. Geometric analysis of occlusal plane orientation using simulated ear-rod face bow transfer. J Prosthodont. 1996;5:172-81.
26. Christensen LV, Slabbert JC. The concept of the sagittal condylar guidance: biological fact or fallacy? J Oral Rehabil. 1978;5:1-7.
27. Shreshta P, Jain V, Bhalla A, Pruthi G. A comparative study to measure the condylar guidance by the radiographic and clinical methods. J Adv Prosthodont. 2012;4:153-7.
28. Nooji D. The third point of reference and its effect on the protrusive condylar guidance angles obtained in semiadjustable articulator. J Indian Prosthodont Soc. 2008;8(2):71-7.
29. Warren K, Capp N. A review of principles and techniques for making interocclusal records for mounting working casts. Int J Prosthodont. 1990;3:341-8.
30. Prajapati P, Sethuraman R, Naveen YG, Patel J. A clinical study of the variation in horizontal condylar guidance obtained by using three anterior points of reference and two different articulator systems. Contemporary Clinical Dentistry. 2013;4(2):162-9.
31. Weinberg LA. An evaluation of face-bow mounting. J Prosthet Dent.1961;11:32-42.
32. Gonzalez JB, Kingery RH. Evaluation of planes of reference for orienting maxillary casts on articulators. J Am Dent Assoc. 1968;76:329-36.
33. Posselt U, Odont DR, Franzen G. Registration of the condyle path inclination by intraoral wax records: Variations in three instruments. J Prosthet Dent. 1960;10:441-53.
34. Craddock FW. The accuracy and practical value of records of condyle path inclinations. J Am Dent Assoc. 1949;38:697-710.
35. Breeding LC, Dixon DL, Kinderknecht KE. Accuracy of three interocclusal recording materials used to mount a working cast. J Prosthet Dent. 1994;71(3):265-70.
36. Michalakis KX, Pissiotis A, Anastasiadou V, Kapari D. An experimental study on particular physical properties of several interocclusal recording media. Part II: Linear dimensional change and accompanying weight change. J Prosthodont. 2004;13(3):150-9.
37. Millstein PL, Clark RE. Determination of the accuracy of laminated wax interocclusal wafers. J Prosthet Dent. 1983;50:327-31.
38. Hart YB, Sandrik JL, Malone WFP, Mazur B, Hart T. Accuracy and dimensional stability of four interocclusal recording materials. J Prosthet Dent. 1981;45(6):586-91.
39. Steele JG, Nohl FSA, Wassel RW. Crowns and other extra coronal restorations: Occlusal considerations and articulator selection. BDJ. 2002;192(7):377-87.
40. Urstein M, Fitzig S, Moskona D, Cardash HS. A clinical evaluation of materials used in registering interjaw relationships. J Prosthet Dent. 1991;65(3):372-7.
41. Breeding LC, Dixon DL. Compression resistance of four interocclusal recording materials. J Prosthet Dent. 1992;68(6):876-8.
42. Shillingburg T, Herbert T, Hobo S, Whitsett LD, Jacobi R, Brackett SE., et al. Fundamentals of fixed prosthodontics. 3rd ed. Lllinois: Quintessence Publishing Co; 1997. P. 42-81.
43. Corbett NE, DeVincenzo JP, Huffer RA, Shryock EF. The relationship of the condylar path to the articular eminence in mandibular protrusion. J Prosthet Dent. 1971;41:286-92.
44. Gray RJ, Quayle AA, Homer K, Al-Gorashi AJ. The effects of positioning variations in transcranial radiographs of the temporomandibular joint: A laboratory study. Br J Oral Maxillofac Surg. 1991;29:241-9.
45. Prasad K, Shah N, Hegde CH. A clinic-radiographic analysis of sagittal condylar guidance determined by protrusive interocclusal registration and panoramic radiographic images in humans. Contemporary Clinical Dentistry. 2012;3(4):383-7.