Abstract
Aims:
To determine the average condylar inclination using ultrasonic axiograph; to determine the average condylar inclination using protrusive interocclusal bite records; to compare whether there is any marked difference in the values obtained by these techniques.
Settings and Design:
This clinical study compares the mean horizontal condylar inclination of the ultrasonic axiograph (Axioquick system) and the manual programming using protrusive interocclusal records.
Materials and Methods:
The study was conducted on a group of 30 subjects reporting to Department of Prosthodontics. Axioquick software system of SAM III (School Articulator Munich) fully-adjustable articulator was used, and interocclusal recording of condylar inclination is the manual method used in semi-adjustable articulators using Aluwax. The condylar inclination of the articulator was adjusted and set using protrusive interocclusal record.
Statistical Analysis:
The horizontal condylar inclination values of both methods were collected, and the mean of right and left condylar inclination was compared using paired t-test.
Results:
A statistically significant difference exists between Axioquick system and the manual method of programming articulator with protrusive interocclusal records (P ≤ 0.001).
Conclusions:
Within the limitations of the present study, the following conclusions were drawn: The average condylar inclination by axiograph is 42.125°. The average condylar inclination by interocclusal record is 33.25°. Comparison of both values shows a difference of 8.88° ± 4.03° that showed a significant difference (P < 0.001).
Keywords: Axioquick system, protrusive interocclusal record, horizontal condylar inclination
Introduction
A fully-adjustable articulator is an instrument that can mechanically reproduce mandibular motion. It has an adjustable intercondylar distance, horizontal, and vertical condylar adjustments, either a straight or a curved horizontal condylar guide, Bennett guide adjustments, and provision for Fischer's angle. These articulators can be manipulated using positional records or with pantographic tracings.[1] In 1896, Johan Ulrich conducted a study on the movements of temporomandibular joint, while opening, protrusion, and lateral movements, as well as on some functional movements. He found that because the condyles begin a forward motion immediately upon jaw opening, a series of the instantaneous axis were responsible for the opening movement. He also described the “envelop of motion” of the mandible on the sagittal plane. He identified the “bodily shift” of mandible on lateral movement, but those studies went unnoticed until about 12 years later Norman G. Bennett described it for the third time.[2,3] Recent advancements in the computer technology have made it possible to analyze mandibular movements with a high degree of accuracy and precision. Beck and Morrison used an electromechanical device to reproduce mandibular motion, with the help of transducers, a recorder-controller, and a duplicator. Messerman also added to this study by placing six linear, optical encoders. His data were recorded on magnetic tape and processed by a digital computer.[4] In the present study, a contactless type of mandiblular tracking device, which is known as Axioquick recording system (SAM III [School Articulator Munich]) and interocclusal record methods were used. A very few studies have been found in the literature comparing condylar inclination determined by axiograph with condylar inclinations recorded by means of programming articulators using protrusive interocclusal records. Hence, it is thought desirable to undertake this present study to evaluate the difference in values determined by two different methods.
Materials and Methods
Computerized axiography
The SAM Axioquick system consisting of a conventional double facebow was attached to the subject. The maxillary and mandibular bows were both equally tightened. The mandibular bow is used to transmit the movements of the hinge axis to the maxillary facebow. The mandibular bow can be adjusted and attach to the mandibular anteriors using clutch system using impression compound to Axioquick recorder [Figure 1]. The maxillary flag bow is placed by seating the porion earpieces inwardly, which helps to position the nasion relator, the vertical head band and rubber neck band, the mastoid bone support, and the secondary tilt support. This system consists of four ultrasonic transmitters in the lower flag bow and eight ultrasonic receivers in the upper flag bow, those sensors help to record the mandibular jaw movements. Axioquick Software System for the computer was then used to receive and process the data from the digitizer flags and electronic sensors, and data will be obtained in graphical and numerical values [Figures 2 and 3] for SAM III fully-adjustable articulator. In this study, the right and left condylar inclination values of SAM III articulator were recorded for thirty subjects.
Figure 1.
Axioquick system
Figure 2.
Graphic representation of values
Figure 3.
Numerical representation of values
Intra-oral method to record protrusive interocclusal records
Interocclusal recording of condylar inclination is the manual method used in semi-adjustable articulators. In this method, impression of subjects was made using alginate (Zelgan Plus, Dentsply) and cast was poured out of it with Type III Dental Stone (Denstone, Pankaj Enterprises). After that, a centric record and a 6mm protrusive records were made using Aluwax (Aluwax Dental Products Co., Michigan, USA) [Figure 4]. Then facebow transfer of the subject was done and the maxillary casts were mounted on to a semi-adjustable articulator (ARTEX CP, AMMAN Girrbach Germany) using Type II Dental Plaster (White Gold, Asian Chemicals). The lower cast is then mounted in centric relation using the centric record, and the condylar inclination of the articulator was adjusted and set using protrusive interocclusal record [Figure 5]. In this study, mean horizontal condylar inclination of thirty subjects, evaluated using Axioquick system, and manual programming of articulators using protrusive interocclusal record were compared to find any significant difference between the two.
Figure 4.
Aluwax bite records
Figure 5.
Articulator programming using interocclusal records
Right and left horizontal condylar inclination values of both Axioquick and manual methods of 30 subjects were collected, and the mean of right and left condylar inclination of both groups were compared using paired t-test.
Results
Totally, 30 subjects were divided into two groups. Group I was the mean of horizontal condylar inclination of right and left condyles, of the 30 subjects were calculated using the Axioquick system, which was 42.13° ± 7.07°. Group II was the mean horizontal condylar inclination of right and left condyles, of the 30 subjects were calculated using manual programming of articulator using protrusive interocclusal record, which was 33.25° ± 6.79°. While comparing the two mean values of two groups using paired t-test [Table 1], the mean between both groups was shown as 8.88° ± 4.03°. The result of the paired t-test shows a significance level of P ≤ 0.001, which shows highly significant difference between the two groups.
Table 1.
Comparison of mean condylar inclination for SAM and Artex articulator
Graph 1 shows the mean condylar inclination values obtained with Axioquick system for SAM III articulator and with the manual programming on Artex arcon semi-djustable articulator.
Graph 1.
Mean condylar inclination for School Articulator Munich and Artex articulator
Discussion
For any successful prosthodontic rehabilitation treatment, there should always be certain questionable procedures were present. Mandibular movement is one among such, which is always a complex procedure to record its entire movement patterns. Studies had described this complex pattern of mandibular movements and had explained various methods to record the same.[5] The first attempt on tracking mandibular movements was on 1889 and that method was known as photographic method.[6] After that several authors had studied on these mandibular movements and tried to record them with the most accuracy.
A pilot study was done,[7] on the compatibility of mechanical and computerized axiograph. In that study, the authors had compared the measurements of both mechanical (SAM Axiograph Axo200) and computerized (SAM Axiotron and Axo500) systems in recording the rotation and translation of mandible. Mechanical method uses grid paper, compass, and ruler; on the other hand, computer was used to perform the recordings in the Axiotron system. And their results show no statistical significance between both systems. They also mentioned that mechanical methods always creates hand measuring errors that can be avoided with the help of computerized or electronic system.
The present study had compared the horizontal condylar inclination measurement recorded using the manual method by making protrusive interocclusal records, to a computerized electronic mandibular tracking device (Axioquick system). The programming of the Artex semi-adjustable articulator was done with the protrusive records, and the Axioquick system provides condylar inclination values for the programming of SAM III fully-adjustable articulator.
Another similar study[8] had done in which the author compared protrusive interocclusal records to pantograph tracings. The study was concluded that there is no statistical significance in recording the horizontal condylar inclination using polyvinylsiloxane material and the pantographic technique.
The results of the study showed that a statistically significant difference exists between Axioquick system and the manual method of programming articulator with protrusive interocclusal records [Table 1]. The mean of right and left condylar inclination values for the SAM III articulator using Axioquick system was 42.13° whereas, in the manual method for Artex articulator, it was 33.25°. A statistical analysis was done to compare both the values using paired t-test with a mean value of 8.88° ± 4.03° which showed a statistically significant difference between both the groups [Graph 1]. These results of the present study indicated the use of electronic mandibular tracking devices in any extensive rehabilitation procedures. The significant differences shown between the two compared groups was mainly because of some of the limitations with the manual errors that could happen on programming the articulator using protrusive interocclusal records. Another problem related to the mandibular clutch attachment was its parallelism toward the maxillary bow.
Studies[9] showed comparison of condylar setting using three different methods consist of electronic pantography, mechanical pantography and simplified mandibular motion analyzers, and concluded that for recording protrusive excursions the electronic pantography was considered the best suitable method with least possible errors.
An in vitro evaluation was done[10] on, the reliability and validity of an electronic pantograph by testing with five different articulators. In which the authors used the Cadiax system to evaluate the condylar setting of five articulator (Denar D5A, Denar Mark II, Whip Mix 8500, Hanau Modular and Panadent PCH). They concluded the study by stating that, the standard deviations for assessing reliability and the mean deviations for assessing validity were both relatively small in comparison to the average values of the condylar determinants. Hence, the electronic mandibular tracking devices were reliable and a valid tool in any extensive restorative procedure.
One of the limitations of this study was observed to be the interference caused while attaching the lower clutch to the madibular dentition, and most of the subjects are not comfortable on using cynoacrylate in their dentition. In such cases, some of the patients were asked to stabilize the mandibular clutch using thumb of both hands; this was also predicted as a limitation, because pressure exerted by the thumb in holding the clutch in its position might alter the original mandibular motions. Another limitation on comparing both the groups was the Artex semi-adjustable articulators measurements are fixed with a condylar inclination level of 5° interval readings.
Thus, the results of the present study strongly recommend the use of fully-adjustable articulators in any type of extensive prosthodontic rehabilitation, which in turn can avoid any sort of discrepancies in the final restoration which causes subtle occlusal interferences leading to intra-oral correction of restorations.
Footnotes
Source of Support: Nil.
Conflict of Interest: None declared.
References
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