Indian Journal of Dental Research

ORIGINAL RESEARCH
Year
: 2015  |  Volume : 26  |  Issue : 3  |  Page : 256--261

Cephalometric evaluation of condyle-fossa position in dentulous and edentulous subjects


M Prabhu Uma1, Shetty Rajesh2, K Shenoy Kamalakanth2,  
1 Department of Prosthodontics, Century International Institute of Dental Sciences and Research Centre, Kasargod, Kerala, India
2 Department of Prosthodontics, Yenepoya Dental College, Mangaluru, Karnataka, India

Correspondence Address:
M Prabhu Uma
Department of Prosthodontics, Century International Institute of Dental Sciences and Research Centre, Kasargod, Kerala
India

Abstract

Context: Whenever there is loss of teeth and occlusion, it triggers a change in the functional and structural relationship of the mandible. Various physiologic factor such as age and changes in occlusion lead to specific remodeling changes in the temporomandibular joint (TMJ). Aims: The aim of this study was to evaluate and compare the influence of dentition on condyle-fossa position by comparing this variable in dentulous and edentulous subjects using lateral cephalogram. Settings and Design: The study was conducted on 25 dentulous and 25 edentulous subjects, comprising of males and females, visiting Yenepoya University, Mangalore. Subjects and Methods: The age ranges of dentulous subjects were 25–30 years and edentulous subjects of 45–65 years with 1–5 years of edentulousness were chosen. Lateral cephalograms were taken, and various reference lines and planes were used to determine the center of condyle and center of the glenoid fossa. Statistical Analysis Used: The results were analyzed by SPSS version 7.0 (SPSS Inc., Chicago) and statistical analysis used was t-test. Results: Condyle was placed upward and forward, and glenoid fossa was situated more anteriorly in edentulous subjects compared to dentulous subjects. Conclusions: This study supports the concept that TMJ is an articular triad with two points of contact provided by TMJ and third contact by the dentition. Alteration in any one of these contact points will produce secondary morphological changes in other two points.



How to cite this article:
Uma M P, Rajesh S, Kamalakanth K S. Cephalometric evaluation of condyle-fossa position in dentulous and edentulous subjects.Indian J Dent Res 2015;26:256-261


How to cite this URL:
Uma M P, Rajesh S, Kamalakanth K S. Cephalometric evaluation of condyle-fossa position in dentulous and edentulous subjects. Indian J Dent Res [serial online] 2015 [cited 2020 Nov 30 ];26:256-261
Available from: https://www.ijdr.in/text.asp?2015/26/3/256/162891


Full Text

The spatial relationship between the temporomandibular joint (TMJ) components is the relative three-dimensional positions of the condyle, glenoid fossa, and articular eminence. Studies have shown that bony surfaces of the skull, face, and jaws retain their ability to undergo remodeling throughout life.[1] The loss of teeth and occlusion triggers a change in the functional and structural relationship of the entire adult mandible. Progressive remodeling is found more often in the anterior aspect of the condyle while regressive remodeling can be seen on the posterior condylar aspect.

The morphology of glenoid fossa varies among individuals and in different dentitions.[2],[3] The temporal part of the TMJ is under the influence of remodeling forces throughout life.[4] The aim of the present study was to evaluate and compare the influence of dentition on mandibular condyle and glenoid fossa position and to compare these variables in dentulous and edentulous subjects using lateral cephalogram.

 Subjects and Methods



A total of 50 subjects (25 dentulous and 25 edentulous), comprising of males and females were selected based on certain criteria which included dentulous subjects in the age group of 25–30 years and edentulous subject of 45–65 years. Dentulous subjects were selected based on a skeletal class I relation. The duration of edentulousness for the selected edentulous subjects was 1–5 years. These subjects were not using complete dentures during their period of edentulousness. The examination was conducted to rule out temporomandibular disorders for the selected subjects.[5] Subject's consent was taken for lateral cephalogram.

To standardize the lateral cephalogram, all of them were taken in the same cephalostat machine by a single operator with the head in a natural posture. Frankfort horizontal plane for the natural head position was standardized by the use of a forehead positioner located at nasion.[6] Once properly positioned, the subject was instructed to close in maximum intercuspation.[7],[8] The subject was then instructed to remain still throughout the exposure.[9] Lateral cephalogram was taken with complete dentures for edentulous subjects, which were fabricated after screening test for TMJ disorder.

The established land marks[10],[11] and planes[10] are used in the study as shown in [Figure 1] and [Figure 2], respectively.{Figure 1}{Figure 2}

In this study, apart from Frankfort horizontal plane and S-N plane[10], nasion perpendicular (N-perpendicular) was used [Figure 2]. A vertical line was drawn perpendicular to the Frankfort horizontal plane and extended inferiorly from the nasion to form N-perpendicular.[12]

For determining the skeletal class I relationship of Maxilla and Mandible Steiner's analysis was used.[13]

To locate the center of condyle following planes are used, which are shown in [Figure 3] and [Figure 4]:{Figure 3}{Figure 4}

Reference line: A line is drawn parallel to the Frankfort horizontal plane and tangent to the most superior aspect of the glenoid fossa.

Line 1: A line is drawn parallel to the reference line and tangent to the highest point of the condyle Line 2: A line is drawn perpendicular to Line 1 and tangent to the most anterior aspect of the condyle Line 3: A line is drawn parallel to Line 2 and tangent to the most posterior aspect of the condyle Line 4: A line is drawn parallel to Line 1, which is at a distance to Line 1 equal to that between Line 2 and Line 3.

The center of the condyle was located as suggested by Brewka, Hatjigiorgis, and Hongchen. Line 1, Line 2, Line 3, and Line 4 were drawn as mentioned above. The four lines were joined together to form a square. The intersection point of the two diagonals of this square represent the center of the condyle [Figure 3] and [Figure 4].[14][15][16]

Constructed planes used for the location of center of glenoid fossa [Figure 3] and [Figure 4]:

Line E-F: A line is drawn parallel to the reference line and tangent to the crest of the articular eminence.

X-axis: A line is drawn midway between and parallel to line E-F and reference line.

Y-axis: A line is drawn perpendicular to the reference line at the point where the reference line intersected the height of fossa.[14][15][16].

The center of the glenoid fossa was located as suggested by Brewka, Hatjigiorgis, and Hongchen. Line E-F, X-axis, and Y-axis are drawn as mentioned above. The point of intersection of the X-axis and Y-axis indicate the center of the glenoid fossa. The distance from the center of the condyle to the center of the glenoid fossa on the X-axis, and the Y-axis was measured and recorded [Figure 3] and [Figure 4].[14][15][16]

Nasion perpendicular was drawn as described by McNamara. A vertical line (N-perpendicular) was drawn perpendicular to the Frankfort horizontal plane and extended inferiorly from nasion [Figure 4].[12]

From the center of condyle and center of glenoid fossa horizontal lines were drawn perpendicular to N-perpendicular to determine the position of condyle and glenoid fossa in dentulous and edentulous subjects, and the values obtained were compared [Figure 4]. [Figure 5] shows tracing done on a lateral cephalogram to locate the centre of condyle and centre of glenoid fossa.{Figure 5}

Tracing was done, and measurements were recorded. The values obtained were tabulated and subjected to statistical evaluation. The mean values were calculated, and t-test was done to assess the level of significance for the condyle-fossa position. P < 0.05 - significant, P < 0.005 - highly significant, P > 0.05 - nonsignificant were used. The results obtained from the statistical evaluation were tabulated in [Table 1]-[Table 4] and graphically represented in [Graph 1] [Graph 2] [Graph 3] [Graph 4]. [Table 5] represents tests of normality and [Table 6] represents comparison of study parametres among dentulous and edentulous subjects. [Graph 5] represents comparison of study parametres among dentulous and edentulous subjects.{Table 1}{Table 2}{Table 3}{Table 4}{Table 5}{Table 6}

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 Results



[Table 1] shows a comparison of mean distance on Y-axis between the center of condyle and center of the glenoid fossa in dentulous and edentulous subjects and their respective standard deviations and probability value. In dentulous subjects, the mean value was found to be 8.020 and standard deviation 0.8718. In edentulous subjects, mean value was found to be 7.380 and standard deviation 1.4950. The results obtained from [Table 1] indicate that the condylar position is slightly upward in edentulous subjects when compared to the dentulous subjects.

P

value was found to be 0.071 which indicates that there is no statistical significance regarding the upward positioning of condyle of edentulous subjects when compared to the dentulous subjects.

[Table 2] shows a comparison of mean distance on X-axis between the center of condyle and center of the glenoid fossa in dentulous and edentulous subjects and their respective standard deviations and probability value.

It was found that dentulous subjects showed a mean distance of 2.220 and standard deviation of 1.2997, whereas in edentulous subjects it was 1.500 and 1.0508, respectively. This result indicates that the condyle is placed forward in edentulous subjects when compared to dentulous subjects. P = 0.036 indicates that there is a statistical significance regarding the forward positioning of the condyle in the edentulous subjects compared to the dentulous subjects.

[Table 3] shows a comparison of the mean distance between N-perpendicular and center of the condyle in dentulous and edentulous subjects and their respective standard deviations and probability value. In dentulous subjects, mean distance between N-perpendicular, and center of condyle were found to be 8.556, and the standard deviation was 0.5980. In edentulous subjects, mean distance between N-perpendicular and center of condyle was found to be 7.944, and the standard deviation was 0.6752. The results obtained from [Table 3] indicate that the condyle is placed forward in edentulous subjects when compared to dentulous subjects.

P value was found to be 0.001. This indicates that there is a statistical significance regarding the forward placement of the condyle in the edentulous subjects when compared to the dentulous subjects.

[Table 4] shows a comparison of the mean distance between N-perpendicular and center of the glenoid fossa in dentulous and edentulous subjects and their respective standard deviations and probability value. The mean distance was found to be 8.320, and the standard deviation was 0.6069 in dentulous subjects. In edentulous subjects, mean distance between N-perpendicular and center of glenoid fossa was found to be 7.776, and standard deviation was 0.6392.

The result shows that the position of the glenoid fossa is placed more anterior in edentulous subjects when compared to dentulous subjects.

P value was found to be 0.003, which indicates that there is a statistical significance in the anterior position of the glenoid fossa in edentulous subjects when compared to the dentulous subjects.

 Discussion



Several authors claim that remodeling is a phenomenon adaptive to functional needs due to forces applied to the bone.[17],[18] The main evidence for remodeling in the TMJ has been from skeletal and autopsy studies. In a skeletal study, it was found that from age 22 years onward, remodeling of some sort was a consistent feature.[19] Remodeling involves both the condylar and temporal component of the joint, although the condylar head frequently showed a greater incidence of change.[20]

After the loss of all teeth in one or both the dental arches, the intercuspal position and the retruded contact position disappear. In these situations, when the maxillary and mandibular residual ridges approximate during the closure of jaws, the position of the condyle in the glenoid fossa may change. This change in condylar position may be pathologic and is referred to as the edentulous position of the TMJ.[15]

In the present study, distance on the Y-axis between the center of the condyle and the center of glenoid fossa was reduced in edentulous subjects when compared to that of dentulous subjects. However, this reduction in the distance was not statistically significant with a P = 0.071. The results obtained in this study indicate that the condyle is placed slightly upward in edentulous subjects when compared with the dentate group. This upward shift of the condyle occurs as a result of loss of natural occlusal stops. This result of the study is in accordance with the study conducted by Hatjigiorgis et al.[14] and Hongchen et al.[15]

Distance on N-perpendicular and center of condyle was reduced in edentulous subjects. The P = 0.001 indicates that the reduced distance between the N-perpendicular and center of the condyle is highly significant which shows that the condyle is placed forward in edentulous subjects when compared to the dentate group.

Myostatic contracture of the lateral pterygoid muscles[21] may contribute to the anterior position of the mandible and this probably could be the reason why condyles may be located anteriorly in edentulous subjects when compared to dentulous subjects.

Distance on X-axis between the center of condyle and center of glenoid fossa decreased significantly in edentulous subjects, with a P = 0.036. The result of this study indicates that the condyle is placed forward in edentulous subjects when compared to the dentulous subjects, in agreement with those of Hatjigiorgiset et al.[14] who stated in their study that the mean condylar position for the edentulous subjects was slightly forward and upward when compared to the dentulous group.

Distance on N-perpendicular and center of the glenoid fossa is reduced in edentulous subjects with a statistical significant P = 0.003. The result of this study indicates that the position of the glenoid fossa is more anteriorly situated in edentulous subjects than in dentulous. This result is consistent with the study conducted by Raustia et al.[22] who concluded that the rate of remodeling, which glenoid fossa undergoes depends upon the rate of edentulousness. This remodeling leads to morphological changes in the structures of the TMJ, leading to its altered position in relation to other anatomical structures associated with it.[22]

 Conclusion



This study suggests that it is important to maintain the proper occlusal stop. Whenever there is loss of natural teeth, they should be replaced immediately with the proper vertical dimension of occlusion and maximum intercuspal position for the function and esthetic as well as for proper positioning of condyle and glenoid fosaa and for a healthy TMJ.

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