INTRODUCTION

Panoramic radiographs (orthopantomograms [OPG]) are the most routinely and widely used diagnostic tool used by the dental clinicians to get valuable information about teeth, mandible and other related structures of the jaw [13]. It gives us valuable knowledge about the anatomical variation of maxilla and mandible and also osseous changes or flattening happening with time [9]. Routine panoramic view has also been recommended by the American Academy of Oral and Maxillofacial Radiology for assessing the structural components of the temporomandibular joint (TMJ) because of the cost and risk of the relatively low radiation exposure associated with computed tomography [7].

Mandibular condyle is an important anatomical landmark for facial growth, expressed in an upward and backward direction [17]. The presentation of mandibular condyle differs widely among different age groups and individuals. Morphological variations depend upon developmental variation along with condylar remodelling to accommodate malocclusion, trauma and other pathological and developmental abnormalities [2]. Variability in the shapes and sizes of condyles helps to diagnose the TMJ disorders associated with malocclusions such as crossbite, deep bite, and open bite [3].

The mandibular condyle varies considerably both in size and shape. The typical condylar head has a convex arrangement throughout, and symmetry should exist between contralateral sides within the same individual [12, 17]. Several studies have endeavoured to assess the morphology of human condyle. Past researchers evaluated a variety within the mandibular condyle shapes [12, 14]. Yale et al. [19] first classifies the shapes of the mandibular condyle as convex, flat and concave when having a superior view by examining the skulls of Terry collection. However, later Yale simplified classification into four categories flattened, convex, angled, rounded [19].

Upon surgical exposure, four different types of condyles shapes were noted, which include excavated form, oblique form, and the small round shape and flattened [11]. On the other hand, flat, convex, concave, round and angled types of condylar morphology were noted when computed tomography images were observed [8].

In Pakistan, limited data is available regarding the morphological appearance of the condyle. The thorough understanding of the morphological variations in the shape of the mandibular condyle is essential so that a standard variant can be distinguished from the abnormal condition. Therefore, this study aims to record different types of normal morphological variations of the condyle through an OPG. The objective of this study is to assess the frequency of different condylar morphological variations in both genders and age groups.

MATERIALS AND METHODS

Study design and patients

The retrospective cross-sectional study was conducted from November 2018 to March 2019 at Dow International Dental College Karachi; it included radiographic evaluation of 500 mandibular condyles. All retrievable OPGs were obtained, and necessary data was extracted regarding age, gender and condylar morphology. Ethical approval for this study was obtained from the Institutional Review Board, Dow University of Health Sciences.

Digital orthopantomograms (OPG) taken on Villa Rotograph EVO 3D, (exposure parameters being: 10 mA, 82 Kv) free of any projection errors, that showed a complete view of condyle on either side with optimum density and contrast were selected. The radiographs of the individuals with a history of TMJ dysfunction, occlusal discrepancy, pathological and developmental abnormalities were excluded.

Sum of 250 OPGs was visualized for a routine investigation. The OPGs were evaluated by two maxillofacial surgeons to determine the morphology of condyle. The statistical analysis was conducted using SPSS version 17. The participants were divided into three groups according to the age: (i) young adults (18–35 years), (ii) middle age (36–55 years), (iii) older adults (56 or above). Descriptive statistics were conducted to estimate the frequency of normal morphological variations of condyles. Chi-square test was conducted to assess the difference in frequency of normal condylar morphological variations about age and gender.

Ethical approval

All procedures performed in studies followed the ethical standards of the institutional research committee and the 1964 Helsinki declaration and its later amendments.

RESULTS

Total of 500 condyles from 250 OPGs was examined. Out of 250 radiographs, half of them belong to females, and half belong to males, as shown in Table 1. In terms of age, the majority of radiographs were of participants belonging to middle age groups, as shown in Table 1.

The shapes of the condyles that have been identified in this study are: bird beak, oval, diamond, and crooked finger, as shown in Figures 1, 2, 3, and 4. The commonest form of condylar morphology was oval (50%), followed by the bird beak (40%), diamond (4.8%) and crooked finger (4.8%). The frequency of oval condylar morphology was 57.6% among males and 42.4% among female participant, as shown in Table 2. In all age groups, the most dominant form of condylar morphology was oval, followed by the bird beak diamond and crooked finger. The frequency of oval condylar morphology was 36% in age group 1, 44% in age group 2 and 20% in age group 3, as shown in Table 2.

Figure 1. Type I — bird beak

Figure 2. Type II — oval.

Figure 3. Type III — diamond.

Figure 4. Type IV — crooked finger.

When the frequency of condylar morphological types was compared with the gender, it was observed that among male study participants, the oval condylar morphology was significantly higher (p = 0.016). On the other hand, among females study participants, the diamond condylar morphology was significantly higher (p = 0.018), as shown in Table 3.

The frequency of condylar morphological types was compared with the age groups in Table 3. Among participants of age group 1, the frequency of diamond condyles was significantly lower as compared to other age groups. In the case of age group 2, the frequency of crooked finger condyles was significantly higher (p = 0.002) as compared to other age groups. Among participants of age group 3 the frequency of bird beak condyles were significantly lower (p = 0.001) as compared to other age groups and diamond condylar morphology was significantly higher (p = 0.0001) as compared to other age groups.

DISCUSSION

The morphological appearances of mandibular condyle have great variation among different age groups and subjects [15, 18]. Normally, we recognize five basic shapes, i.e. oval, bird beak, crooked finger, diamond and mixed. In Pakistan, limited data is available regarding the morphological appearance of the condyle. Therefore the present study highlights the prevalent radiographic shapes of the condylar head-on OPG. Out of 250 pair of condylar heads that were evaluated, 50% were oval, 40% bird beak, 4.8% crooked finger and diamond 4.8%. In our study, the oval condylar morphology was most common and significantly higher among male individuals (Table 3). The studies reported by Choudhary et al. [6] and Ribeiro et al. [14] pertaining to the Brazilian and East Indian population respectively showed round/oval shape to be common in both sexes which goes in accordance with our study.

The morphological knowledge of the TMJ is an important tool for evaluation of normal growth and development. This may also be helpful in the near future for the development of forensic odontology [6, 8, 17]. The growth of mandibular condyle is indicated in an upward and backward direction. It is considered as major areas of facial growth. The appearance and the shape of mandibular condyle vary enormously among individuals and different age groups, which is in accordance with the present study [11–13].

The present study on the radiological examination using OPG revealed flat, pointed, angled and round condylar morphology. Similarly, several other studies also showed the bird beak, oval, diamond, and crooked finger type condylar morphology [1, 10, 18]. In our study the second most common condylar morphology observed was bird beak. The frequency of bird beak condylar morphology was higher among females as compared to males. However, no statistically significant difference was observed when both genders were compared (Table 3). Similarly, Sonal et al. (2016) [16] also reported the bird beak as a second most common condylar morphology among females. On the other hand, the diamond and crooked finger morphology were a rarity [4, 18].

We compared the participant age with the condylar morphology. However, to our knowledge, no such data is reported in previous studies; thus, a comparison is not possible. The diamond shape condyles were significantly higher among participants of age group 3 as compared to other age groups (Table 4). The frequency of crooked finger condyles was significantly higher among participants of age group 2 (Table 4). The frequency of bird beak condyles was significantly higher among group 1 and 2 as compared to group 3 (Table 4).

In comparison of our results, several other studies investigated that it is very important to evaluate condyle morphology with changes in condyle surface shapes, radiological dimensional measurements with malocclusion. A study reported that there was a significant relation between open bite and erosion of the head of the condyle. Ari-Demirkaya et al. [5] found that there was no difference between open, deep or normal bite groups in subjects with different condylar morphology.

Currently, various advanced radiographic modalities are available, such as computed tomography scan, cone beam volumetric imaging, which can give detailed information of the condyle. However, oral health practitioners usually prefer OPG to screen TMJ. The possible explanation due to which oral health practitioners still prefers OPG include favourable cost-benefit relationship, low doses of radiation exposure, ease of prescription and lack of image superimposition [4, 14, 15]. The use of OPG has its limitations such as a two-dimensional view. In addition to that, the limitations of this study include small sample size and lack of examiner reliability.

CONCLUSIONS

In conclusion, all four morphological types of mandibular condyles were observed and the oval shape condyles were most prevalent among both genders and all age groups. In future studies, the inclusion of other parameters and large sample size may provide unique information.

Acknowledgements and funding

The authors extend their appreciation to the Deanship of Scientific Research at King Khalid University, KSA for funding this work through research groups programme under Grant No. RGP.1/343/42.

Conflict of interest: None declared