|Year : 2020 | Volume
| Issue : 4 | Page : 550-554
Evaluation of sagittal condylar guidance angles using computerized pantographic tracings, protrusive interocclusal records, and 3D-CBCT imaging techniques for oral rehabilitation
TA Naqash1, S Chaturvedi1, A Yaqoob1, S Saquib2, MK Addas1, M Alfarsi1
1 Department of Prosthetic Dentistry, College of Dentistry, King Khalid University, Abha, Saudi Arabia
2 Department of Periodontics and Community Dental Sciences, College of Dentistry, King Khalid University, Abha, Saudi Arabia
|Date of Submission||10-Oct-2019|
|Date of Acceptance||07-Dec-2019|
|Date of Web Publication||4-Apr-2020|
Dr. T A Naqash
Department of Prosthetic Dentistry, College of Dentistry, King Khalid University, Guraiger, 62529 Abha
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Objective: The goal of registering the condylar guidance is to recreate the patient's occlusion as exactly as possible on the articulator, and is therefore essential for successful prosthodontic rehabilitation. Clinical, radiographic, and pantographic methods are used to determine sagittal condylar guidance angles (SCGAs). These methods generate different angles in the same patients. The present study is the first disquisition to evaluate and correlate SCGAs determined by the use of pantographic tracing (PT), protrusive records (PR), and radiographic (CBCT) techniques. Materials and Methods: The condylar guidance was measured using PT, PR, and CBCT imaging techniques in 23 nonpatient participants aged between 18 and 30 years irrespective of sex. PT was recorded using Cadiax® Compact system, a computerized recorder of SCGAs. PR was obtained using polyvinyl siloxane bite registration material, transferred to a semiadjustable articulator (Denar Mark II, Whip Mix Corp., USA) using facebow transfer (Denar Mark II, Whip Mix Corp., USA) and CR records, to determine SCGAs. Images of the mid-facial region were obtained using CBCT scan for 3D reconstruction. The angle formed between Frankfort horizontal plane (FHP) and a line extending from the most supero-anterior point on the glenoid fossa to the most convex point on the apex of articular eminence (AE) was measured to obtain SCGAs. Results: The mean left and right SCGAs were as follows: PT (34.42° and 33.93°, respectively), PR (32.14° and 31.82°), and CBCT (38.96° and 38.12°). The Pearson coefficients for the correlations with PT and PR on the left and right sides were 0.899 and 0.907, respectively, while it was 0.911 and 0.934, and 0.842 and 0.874 from PT and CBCT, and PR and CBCT, respectively. Conclusion: Strong correlations were found between SCGAs obtained using PT, PR, and CBCT techniques.
Keywords: CBCT scan, pantographic tracing, protrusive interocclusal records, sagittal condylar guidance angle
|How to cite this article:|
Naqash T A, Chaturvedi S, Yaqoob A, Saquib S, Addas M K, Alfarsi M. Evaluation of sagittal condylar guidance angles using computerized pantographic tracings, protrusive interocclusal records, and 3D-CBCT imaging techniques for oral rehabilitation. Niger J Clin Pract 2020;23:550-4
|How to cite this URL:|
Naqash T A, Chaturvedi S, Yaqoob A, Saquib S, Addas M K, Alfarsi M. Evaluation of sagittal condylar guidance angles using computerized pantographic tracings, protrusive interocclusal records, and 3D-CBCT imaging techniques for oral rehabilitation. Niger J Clin Pract [serial online] 2020 [cited 2020 Nov 24];23:550-4. Available from: https://www.njcponline.com/text.asp?2020/23/4/550/281931
| Introduction|| |
Several reports on the condylar mechanism and efforts to register mandibular movements date back to the late 18th century. The goal of registering the condylar path is to recreate the patient's occlusion as exactly as possible on the articulator, and is therefore essential for successful prosthodontic rehabilitation.
According to Glossary of Prosthodontic Terms (GPT-8), condylar guidance is the mandibular guidance generated by the condyle and articular disc traversing the contour of the glenoid fossa. Failure to record condylar guidance accurately leads to occlusal interferences during mandibular movements, thereby increasing chair-side prosthesis adjustment time that is frustrating for both the patient and the clinician.
Various intraoral and extraoral methods have been used to determine SCGAs; these angles are used to set the condylar elements of the articulator to reproduce inclinations, which are similar or comparable to that of the patient's temporomandibular articulation. Therefore, the accuracy of restored occlusion in a patient is determined by the reliability and precision of these methods used for programming the articulators.
Intraoral methods include interocclusal protrusive records, leaf gauge, Lucia jig, and intraoral tracers. Extraoral methods include the use of radiographs,, (lateral cephalograms, pantomographs, and tomographs) and pantographs.
Since 1905, when Christensen advocated the use of protrusive wax records to determine condylar guidance angle directly on the articulator, there has been disagreement about this technique. Several studies have shown the unreliability of recording and reproducing condylar guidance using intraoral methods; varying inclinations have been registered with consecutive registrations, between recording materials, and between articulators.,,
Pantographic tracing (PT) graphically records the movement of the mandible in three planes and records information on mandibular movements including condylar guidance. PT can be either mechanical or electronic.
The accuracy of electronic pantographs has been evaluated in various studies. Chang et al. demonstrated in anin vitro study that the Cadiax Compact electronic pantograph was both reliable and valid in calculating condylar settings for 5 different articulators. Schierz et al. established that SCGAs can be assessed with satisfactory reliability using computerized PT and are independent of the status of the dentition, which has no statistically significant impact on the measures. Furthermore, Ahangari et al. evaluated the accuracy of Cadiax® Compact II in recording preadjusted condylar inclinations on fully adjustable articulator; results showed that Cadiax Compact® is an accurate and reliable instrument for diagnostic purposes, yielding reproducible measurements.
Radiographic measurements involve stable bony landmarks and can be easily standardized. Several previous studies have investigated the use of radiographic imaging for measuring SCGAs. However, most studies used panaromic imaging and lateral cephalograms for recording SCGAs,,, with very few using CBCT images.,
The use of CBCT has gained popularity in recent times. Digital CBCT scans are safer, more accurate, and comparatively cheaper, resulting in their widespread application in various fields of dentistry.,, More reliable results can be expected using digital CBCT imaging when measuring SCGAs.
The present study aims to correlate the SCGAs obtained from PT, PR, and CBCT techniques.
| Materials and Methods|| |
Twenty three nonpatient participants, aged 18–30 years (mean age 25), of either sex, were selected as per the inclusion and exclusion criteria. Inclusion criteria included patients having a full complement of maxillary and mandibular teeth (except for the third molars), class I molar relation, 2–4 mm of overjet, and available anterior guidance. Exclusion criteria included subjects with signs and symptoms of temporomandibular disorder, lack of suitable neuromuscular control of jaw movements, major restorations, gross attritions, and pregnancy.
Description of the instruments and procedures to be performed was preexplained to the participants, trained to minimize errors imposed by mandibular movement, and consent form was signed.
Pantographic tracing (PT)
Pantographic tracings were recorded for each joint using Cadiax® Compact II (GAMMA Dental, Austria), an electronic 3-D TMJ recorder of condylar inclination, as per the manufacturer's instructions. The Cadiax® Compact II utilizes an arbitrary transverse horizontal axis as the reference axis for recording the mandibular movements. The tracking device of the Cadiax® Compact II consists of a maxillary and mandibular face-bow to which the sensors and styli of the measuring unit are attached, respectively.
The participants, in an upright position, were guided into centric relation (reference position) with unforced chin point guidance. Next, all the movements (open/close, protrusion, and right/left excursion) were performed thrice. Cadiax® was calibrated in advance before each movement [Figure 1].
Protrusive interocclusal record (PR)
Maxillary and mandibular impressions were made using irreversible hydrocolloid (Jeltrate Plus; Dentsply, Del.), poured immediately by dental stone type III (Fuji Rock; GC, Belgium), and mounted with mounting plaster (elite arti, Zhermack) using facebow (Denar Mark II, Whip Mix Corp., USA) and centric relation records.
The participants, in an upright position, were trained to move the mandible forward till the teeth were in an edge-to-edge position. PR was established using polyvinyl siloxane bite registration material (Jet Blue Bite, Coltene, Germany.). Three PR were obtained.
The SCGAs were determined using PR on the Denar Mark II articulator (Whip Mix Corporation, USA.), and the mean of the three measurements was calculated [Figure 2].
|Figure 2: SCGAs has been adjusted on the semi adjustable using protrusive intra oral records|
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Images of the midfacial region of selected subjects were obtained using a CBCT scan (KaVo 3D eXam; Kavo Dental, Germany.) according to the manufacturer's instructions. 3D reconstruction of the images was done using the appropriate software (Syngo fast View VX 57H31, Siemens Erlanger Germany.). FHP was marked by joining orbitale and porion. The mean curvature line was drawn along the posterior slope of AE, extending from most supero-anterior point on the glenoid fossa to the most convex point on the apex of AE.
The angle formed from the intersection of FHP and mean curvature line of AE was measured for both the right and left sides to obtain respective SCGAs [Figure 3].
| Results|| |
IBM SPSS Statistics 25 and Excel 2016 were used for statistical analysis. The data were subjected to t-test [Table 1] and Pearson's correlation test [Table 2] to compare the right and left sides and to correlate the different methods used to measure SCGAs. The reliability of the measurements was confirmed using Cronbach's α values [Table 1].
|Table 1: Comparison of right and left SCGA obtained in degrees from different methods|
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|Table 2: Pearson correlation test for comparison between different techniques|
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Mean left and right SCGAs values obtained in degrees from PT were 34.42° ± 5.13° and 33.93° ± 5.33°, respectively; while it was 32.14° ± 4.32° and 31.82° ± 4.53°, and 38.96° ± 4.19° and 38.12° ± 4.81° from PR and CBCT, respectively [Table 1] and [Graph 1]. The SCGAs were significantly higher for CBCT technique than for the PR (6°–7°) and for the PT technique than for the PR (2°–3°). However, the difference between the left and right measurements obtained from different techniques was statistically insignificant.
The mean values obtained from the PT, PR, and CBCT techniques provided high Pearson's coefficient for the left and right side indicating a strong correlation between all the techniques used [Table 2].
| Discussion|| |
Evaluation and improvement of the accuracy of materials, instruments, and imaging techniques lead to progress in the quality of treatment. This study was conducted to compare SCGAs determined by three different techniques for diagnostic, clinical, and research-based practices.
The null hypothesis was rejected since significant differences were found in the SCGAs obtained between PT, PR, and CBCT imaging techniques (P < 0.05).
SCGA values obtained from CBCT were significantly higher than values obtained from PR. Christensen and Slabbert found that SCGAs obtained radiographically are higher than those determined by intra-oral methods. Shreshta et al. compared condylar guidance obtained by CT and clinical methods; SCGAs obtained by CT were about 10° more than clinical methods. Similar results were testified by Kwon et al. where SCGA values obtained from CBCT measurements being 5°–6° higher than those from protrusive occlusal records.
In this study, SCGA values obtained from PT were found to be closer to the SCGA values obtained from PR than that from CBCT. The results are similar to the preliminary study conducted by Torabi et al.: SCGA values obtained from PT (Cadiax®) being 2° higher than silicone intraoral records and statistically significant for all measurements. According to the literature, an error within 3.4° in the condylar setting seems acceptable for clinical use.
Cronbach's α was high for PT and CBCT, indicating a high internal consistency. Therefore, measuring the SCGA using CBCT images and pantographic tracings might indeed be a useful method. However, the value was low for PR indicating inconsistency. The present study is in agreement with the previous studies showing intraoral methods (PR) of recording SCGAs have lower level of reproducibility and are subject to variation of instrument, operator, and occlusal records.,,
PR technique for measuring SCGAs, regardless of the material used, is inconsistent and lack precision; results from the previous studies, have reported significant differences between instruments and also between consecutive registrations for the same patients. Gross et al. have reported that Hanau consistently gave the lowest SCGA values and Whip Mix the highest, in the same patient.
The problems with the PR technique is that the SCGA values change with the degree of protrusion and represents only one point along the condylar path. Semiadjustable articulators are unable to reconstruct the condylar movements adequately because of their fixed inter-condylar distance and straight condylar pathway.
Strong correlations between SCGAs measured using PT, PR, and CBCT were recorded; the difference among PT, PR, and CBCT was consistent. Therefore, a clinically applicable SCGAs can be obtained by adjusting the value measured using CBCT images and pantographic tracings.
| Conclusion|| |
Strong correlations were detected between the SCGAs obtained using pantographic tracings, CBCT imaging, and protrusive occlusal records. The CBCT values were 6°–7° and pantographic tracing values were 2°–3°, respectively, higher than those obtained using the protrusive occlusal records.
Research Ethics Committee, College of Dentistry, King Khalid University reviewed and approved the study protocol (SRC/ETH/201819/111).
The authors extend their appreciation to Mr. Javid Rasool (Bright X-rays – Complete Dental and Maxillofacial Imaging Centre) for taking 3D CBCT images of the Temporomandibular joints of the participants. The authors also extend their appreciation to the Maxillofacial Centre at College of Dentistry, King Khalid University for providing financial support.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form, the participants have given their consent for their images and other clinical information to be reported in the journal. The participants understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Financial support and sponsorship
The authors extend their appreciation to the Collaborative Centre of Creative Maxillofacial Research and Treatment Modalities at College of Dentistry, King Khalid University for funding this work under grant number MRMC-01-019-007.
Conflict of Interest
The authors declare that there are no conflicts of interest regarding the publication of this article.
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[Figure 1], [Figure 2], [Figure 3]
[Table 1], [Table 2]