Accuracy of recording horizontal condylar inclination and Bennett angle with the Cadiax compact

This study assessed the accuracy of an electronic hinge axis tracing device (Cadiax compact) in measuring the horizontal condylar inclination (HCI) and the Bennett angle. The hinge axis movements were simulated with an articulator to which the hinge axis tracer was attached. On the articulator the pre-set HCI values were 20 degrees, 40 degrees and 60 degrees, the pre-set Bennett angles were 0 degrees, 5 degrees, 10 degrees, 15 degrees, 20 degrees. The maximum measuring errors ranged from 0 to 3.4 degrees (in average 1.2 degrees ) and yielded statistically significant differences between articulator setting and Cadiax compact measurement (P < 0.05) except the HCI of 40 degrees and the Bennett angle of 0 degrees. Because of the small range of the maximum measuring error the Cadiax compact represented reasonable accuracy for clinical application in anterior guidance restorations.     

The Bennett angle. Clinical comparison of different recording methods

The use of interocclusal records with semi-adjustable articulators has been proposed as an easier alternative to axiograph. The operator measured the Bennett angle of 30 participants using an axiograph Quick-Axis, an arcon Whip-Mix and non-arcon Dentatus articulators. Wax and polyether interocclusal recording materials were used with both types of articulators. Compared to the reference axiograph, the Whip-Mix plus wax combination was the nearest one and the Dentatus plus polyether was the most significantly different combination.     

A clinical study of graphic registration of the condylar path inclination

The angular values of the CSP registered from 390 patients and obtained by tracing a tangent to the graph with the GR were analyzed.The data subjected to statistical analysis gave a median angular value of the CSP equal to 33 degrees and showed a great median value dispersion. A low error index was obtained in tracing the tangent to the CSP tracing with the GR method. The angular values of the CSP were repeatable over time since the variations found were less than 5 degrees. Variations of the CSP greater than 5 degrees were noted after repeated registrations in patients with TMJ disturbances as well as in patients treated with complete dentures.These data show the necessity for an individual measurement of the CSP value, especially in patients who need extensive readjustments of the prosthesis.     

Influence of condylar guide inclination on condylar positioning during clenching

The relationship between the steepness of the articular eminence and the condylar positioning during clenching was investigated in 19 volunteers with natural dentitions. The condylar positioning during maximal voluntary contraction was measured using a mandibular movement analysis system with six degrees of freedom. The sagittal condylar guide inclination was also measured using the same apparatus. A significant negative correlation was observed between the sagittal condylar guide inclination and the distance of ipsilateral condylar positioning. This result suggests that the steepness of the articular eminence is an important factor in condylar positioning during clenching.     

Impact of mounting methods in computerized axiography on assessment of condylar inclination*

Objective: Valid and reliable recording is a key requirement for accurately simulating individual jaw movements.

Methods: Horizontal condylar inclination (HCI) and Bennett’s angle were measured using a digital jaw tracker (Cadiax® Compact 2) in 27 young adults. Three mounting methods (paraocclusal tray adapter, periocclusal tray adapter, and tray adapter with mandibular clamp) were tested.

Results: The mean values of the HCI differed by up to 10° between the mounting methods; however, the values for Bennett’s angle did not differ substantially. While the intersession reliability of the Bennett’s angle assessment did not depend on the mounting method, the reliability of the HCI assessment was only fair to good for the paraocclusal mounting method but poor for both periocclusal mounting methods.

Discussion: For attaching the tracing bow of jaw trackers to the mandible, a paraocclusal tray adapter should be applied, to achieve the most reliable results.     

Measurements of the sagittal condylar inclination: intraindividual variations

Aims: Sagittal condylar inclination is an important parameter during fabrication of prosthetic restorations. Existing data about intraindividual variations of sagittal condylar inclination are scarce. The purpose of this study was to investigate intra- and interindividual variations of the sagittal condylar inclination, depending on the position of the condyle in the temporomandibular joint.

Methodology: The study included 51 subjects with Angle’s Class I occlusion (21–32 years of age, mean 25·1). Measurements were done using an electronic axiograph. After a paraocclusal tray was fixed in the mouth, every subject had to make three protrusive movements, from which the device’s software calculated the mean left and mean right sagittal condylar path. The mean left and right condylar path of each subject was divided into three equal sequences, based on whole condylar path length. Condylar inclination values for the first, second and third movement sequences were calculated.

Results: Results showed significant differences between movement sequences (P<0·05). For the left joint, condylar inclination values in the first condylar movement sequence demonstrated, on the average, 14·4% higher values compared to the second movement sequence, and 39·2% higher values than in the third movement sequence. For the right joint, the first condylar movement sequence demonstrated, on the average, 15·8% higher values compared to the second movement sequence, and 41·5% higher values than the third movement sequence.

Conclusions: Results suggest that condylar movement in the sagittal direction is not uniform. Mean left and mean right condylar inclination values do not necessarily describe the actual condylar path, nor do they give adequate information for articulator setup. Left–right side condylar inclination differences greater than 10° can be considered as normal.     

The Gothic arch (needle point) tracing and condylar inclination

The records of 11 patients referred for treatment of TMJ disorders were used to compare condylar inclination found by drawing a tangent and by using a mathematic technique. Needle point tracing angles were also measured for the same patients and were compared with the condylar inclination. It can be concluded that (1) the mathematic technique outlined records a more accurate condylar angulation, and (2) there is a great variation in condylar inclination values between patients and between left and right sides of the same patient, and (3) there is no direct relationship between condylar inclination and the needle point tracing angle.     

Analysis of sagittal condylar path inclination in consideration of Fischer's angle

This study investigated the sagittal condylar path during protrusive and lateral excursions by analysing the actually measured jaw movement data and re-evaluated the setting of the sagittal condylar path inclination in consideration of Fischer's angle. Protrusive and lateral excursions of 10 healthy subjects were measured using a three-dimensional mandibular movement analysing system. Condylar path inclinations at the hinge-axis point and the corresponding external point laterally extending from the condyle were evaluated in the sagittal plane. Fischer's angle was defined as the difference between the sagittal condylar inclinations during protrusive and lateral excursions on the non-working side, by keeping the corresponding horizontal distance from the intercuspal position (ICP) equivalent at the incisal point. Analysis was performed at three different magnitudes of excursions, where the incisal point was located at 1, 3 and 5 mm away from the ICP. There was no significant difference in the sagittal condylar path inclination or the Fischer's angle between two condylar reference points. However, they were significantly different across the three different magnitudes of excursions for both condylar reference points, i.e. sagittal condylar path inclination (P = 0.003 for protrusive excursion, and P < 0.001 for lateral excursion respectively; two-way repeated-measures anova), and Fischer's angle (P = 0.013, two-way repeated-measures anova) became smaller as the incisal point became distant from the ICP. Moreover, 3- and 5-mm eccentric positions were included in the 95% CI where Fischer's angle equals zero and were considered to be clinically acceptable to adjust the sagittal condylar inclination on the semiadjustable articulators.     

A comparison of 3 methods of face-bow transfer recording: implications for orthognathic surgery.

PURPOSE: The purpose of this study was to compare the occlusal plane inclination of models mounted using 3 different systems for face-bow transfer with the actual occlusal plane inclination as measured on a cephalometric radiograph. PATIENTS AND METHODS: Twenty-two subjects were enrolled in this study. Three alginate impressions of the maxillary dentition were taken, and 3 stone dental models were produced for each subject. Face-bow recordings were obtained on each subject using the SAM Anatomical Face-bow (Great Lakes Orthodontics Products, Ltd, Tonawanda, NY), the Erickson Surgical Face-bow (Great Lakes Orthodontics Products, Ltd) and a new technique developed by one of the authors (J.G.). For each subject, the dental models were mounted on a SAM articulator using each of the 3 face-bow recordings. Finally, a lateral cephalometric radiograph was obtained for each subject. The occlusal plane inclination was measured on the models and on the cephalometric radiographs. Differences among groups were tested using a 1-way analysis of variance. Bonferroni test was used for post hoc comparison between different pairs of groups. RESULTS: The average occlusal plane inclination using the SAM Anatomical Face-bow was 7.8 degrees +/- 4.2 degrees greater than the actual-a difference that was statistically significant. The mean occlusal plane inclination of the models obtained using the Erickson Surgical Face-bow was 4.4 degrees +/- 2.2 degrees greater than the actual-a difference that was also statistically significant. The mean occlusal plane inclination of the models obtained by the new technique was only 0.9 degrees +/- 1.2 degrees greater than the actual; this difference was not statistically significant. CONCLUSIONS: The new mounting technique is more accurate than the conventional SAM Face-bow or the Erickson Face-bow for reproducing the actual occlusal plane inclination.     

Lateral condylar movement: recording and transfer from the physiologic closing path

The lateral condylar movement can be observed through cat scan images. A clinical method based on the muscular disconnection can be done after recording the physiologic arc of closure. The incisal jig and the relined occlusal basis are used to transfer the immediate side shift, the Benett movement the lateral progressive movement and the condylar inclination on a full adjustable DENAR D5A articulator.     

The effect of three different recording materials on the reproducibility of condylar guidance registrations in three semi‐adjustable articulators

Sagittal condylar guide settings of three semi‐adjustable articulators: WhipMix^®, Hanau 158^® and Denar Mark II^® were compared using registrations of base plate wax, copper wax and self‐curing acrylic resin in two subjects. Four‐way ANOVA showed differences between instruments ( P < 0·0001), materials ( P < 0·0001), registrations ( P < 0·0001), and no difference between operators. Mean differences between materials were 3°and 6° within the range of registration and articulator variability. Denar Mark II^® gave the highest values, Hanau 158^® the lowest with pantronic values generally lower than articulator settings. Neither acrylic nor copper wax were superior to base plate wax. This and previous studies show low reproducibility and variability between instruments, occlusal records and registration material.     

The clinical and radiographic characteristics of condylar osteochondroma

Osteochondroma is one of the most common benign bone tumors, but it is rare in the mandibular condyle. The purpose of this study was to increase the clinical and radiographic cognition of osteochondroma in the mandibular condyle. Thirty-four patients with radiographic and pathologic features of unilateral condylar osteochondroma were included in this retrospective study. All cases received clinical and radiographic examinations before tumor resection. Common manifestations included facial asymmetry, hypomobility, malocclusion, joint dysfunctions, and even external auditory canal stenosis. Osteochondroma might arise on the different condylar areas, such as the medial aspects (55.9%), anterior-superior (11.8%), posterior-superior (11.8%), lateral (8.8%), and generally enlarged (11.8%). The tumor formed a pseudojoint under the anterior eminence in 55.9%; the affected mandible presented normal shape in 58.8%; and horizontal mandibular deviation was caused by the tumor or elongated ramus in 70.6%. The condylar osteochondroma may locate in different positions encircling the condyle, which increases recognition and diagnosis of these lesions.     

The condylar asymmetry measurements in different skeletal patterns

In the present study, condylar asymmetry measurements were investigated on the lateral cephalometric head radiographs and the panoramic radiographs of 72 subjects (36 males and 36 females), aged 12-16-years and having different skeletal patterns. The lateral cephalometric head radiographs were divided into three groups according to the ANB angle: ANB angles smaller than 1 degrees, between 1 degrees and 5 degrees, and larger than 5 degrees. In addition, each group was also divided into two subgroups according to sex. The effects on the ANB angle and sex on the condylar asymmetry measurement were investigated on the panoramic radiographs by means of variance analysis. It was observed that while condylar + ramus ratio measurement was affected by the change of ANB angle, the other measurements were not affected by it.     

Development of a new device for recording condylar head movement

Several excellent devices have recently been developed to precisely record mandibular movement. However, these devices are not always suitable for use under certain conditions, such as during sleep, because they incorporate a face bow unit. We report here a newly developed, easy and convenient recording device that does not require the use of an instrument within the mouth. Instead, a subminiature pressure transducer is inserted between the outer surface of a fixation device in the external auditory meatus and the anterior cutaneous surface of the external auditory meatus. The fixation device was made using silicone impression material in the shape of the inner external auditory meatus. Following moulding, the material was cut in half and the parts were reconnected using a coiled spring. This method is based on a routine clinical method for palpating the external auditory meatus to observe condylar head movement. By comparing the results obtained using this device with those obtained using CADIAX, we confirmed that it is useful for recording the movement of the condylar head in routine clinical examinations.     

Anatomic and statistical study to determine the inclination of the condylar long axis

The importance of the inclination of the CLA in laminagraphy and OLTP was considered. An anatomic-statistical study of this inclination was conducted and discussed.The necessity of an individualized measurement of the angle between the CLA and the frontal plane was noted. A new device used for this measurement was described.     

The molecular markers for condylar growth: Experimental and clinical implications

The outpour of new research has led to the identification of several factors that play an important role in condylar growth. The objectives of this review are to present the molecular markers that regulate the growth of different cells in the mandibular condyle and their impact on clinical use of functional appliance. The proliferative layer in the mandibular condyle houses a great number of undifferentiated mesenchymal cells that provide the pool of chondrogenic cells. Therefore, it is important to understand the factors that regulate the cell cycle of these replicating mesenchymal cells as well as the factors that control their differentiation to chondroblasts. These chondroblasts in turn are engaged in cartilage matrix synthesis. Therefore, it is critical to present the factors that regulate matrix formation.The process of maturation of chondrocytes into hypertrophic chondrocytes directly impacts the number of cell replication cycles and indirectly affects growth. Therefore, it is of great importance to review the factors that regulate chondrocytes maturation. Hypertrophic chondrocytes secrete hypertrophic matrix with its type X collagen that marks the onset of endochondral ossification.Angiogenesis is regulated by vascular endothelial growth factor (VEGF), and the new blood vessels are rich depository of mesenchymal cells. Factors that regulate the differentiation of these cells into osteogenic cells are critical to growth of the condyle.Understanding of these markers and their levels of expression provides the basis for application of different treatment modalities in the area of growth modification. Furthermore, the identification of factors critical to condylar growth provides us with candidate genes for future gene therapy.