|Year : 2021 | Volume
| Issue : 2 | Page : 129-134
Cone-Beam computed tomographic evaluation of pneumatized articular eminence and roof of glenoid fossa in north- east Indian population
Saumya Verma, Sri Krishna Koppula, Anand Choudhary, Devarshi Nandi, Ashutosh Kumar, Babita Rawat
Department of Oral Medicine and Radiology, Hazaribag College of Dental Sciences and Hospital, Jharkhand, India
|Date of Submission||05-Dec-2020|
|Date of Decision||19-May-2021|
|Date of Acceptance||24-May-2021|
|Date of Web Publication||23-Jun-2021|
Dr. Saumya Verma
Department of Oral Medicine and Radiology, Hazaribag College of ental Sciences and Hospital, Hazaribagh 825 301, Jharkhand
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Background: Pneumatized articular eminence (PAT) and roof of the glenoid fossa (PRGF) are recognized when accessory air cells are found within the zygomatic process of the temporal bone. Pneumatization in this region facilitates the spread of tumors and fractures. During Zygomatic implant placement and TMJ surgical procedures, namely eminectomy and miniplate insertions, various complications might arise due to pneumatized PAT and PRGF. Cone-beam computed tomography (CBCT) provides reliable and accurate information to determine the characteristics, the extent of pneumatization, and its relationship to the adjacent structures. So, recognizing the variations of PAT and PRGF in different populations is of clinical importance. Objective: The purpose of this study was to assess the prevalence of pneumatization of articular tubercle (PAT) and pneumatization of PRGF in the North- East Indian population by using CBCT. Materials and Methods: The study was carried out among 500 patients. The prevalence and significance of differences among the variables were carried out by analysis of variance (ANOVA) and Chi-square test. Data were analyzed by using Statistical Package for the Social Sciences (SPSS) software program, version 21 (IBM). Results: The mean age with pneumatization was 45.27 ± 18.00 years. The prevalence of PAT and PRGF was found to be 24.6% and 24.4%, respectively. Bilateral PAT was detected in (6%) patients. The occurrence of unilateral PAT cases was found to be more than bilateral PAT cases (<0.042). Conclusion: There is a greater prevalence of PAT and PRGF in the North- East Indian population when compared to other similar studies in the literature.
Keywords: Cone-beam computed tomography, external root resorption, impaction, pneumatization
|How to cite this article:|
Verma S, Koppula SK, Choudhary A, Nandi D, Kumar A, Rawat B. Cone-Beam computed tomographic evaluation of pneumatized articular eminence and roof of glenoid fossa in north- east Indian population. J Indian Acad Oral Med Radiol 2021;33:129-34
|How to cite this URL:|
Verma S, Koppula SK, Choudhary A, Nandi D, Kumar A, Rawat B. Cone-Beam computed tomographic evaluation of pneumatized articular eminence and roof of glenoid fossa in north- east Indian population. J Indian Acad Oral Med Radiol [serial online] 2021 [cited 2021 Jul 29];33:129-34. Available from: https://www.jiaomr.in/text.asp?2021/33/2/129/319072
| Introduction|| |
The mainstay of three-dimensional (3D) maxillofacial radiology is the diagnosis of conditions not readily visualized on conventional radiographs. Many bony landmarks are seen on a normal skull cone-beam computed tomography (CBCT) and the need to recognize and document these cannot be overemphasized. One such landmark is the zygomatic process of the temporal bone. Pneumatized articular eminence (PAT) and roof of the glenoid fossa (PRGF) are recognized when accessory air cells are found within the zygomatic process of the temporal bone [Figure 1].
|Figure 1: Accessory air cells are found within the zygomatic process of temporal bone|
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Historically, Wittmaach carried out extensive research on pneumatization of temporal bone using skull radiographs in the early twentieth century. Tyndall and Matteson first documented the air cells of the zygomatic arch in 1985 using panoramic radiographs. CBCT has been used to avoid the superimposition of bony structures over the neighboring areas and has the advantage of low radiation exposure when compared to CT.
Surgical manipulation is required to place zygomatic implants. PAT and PRGF can cause fractures in the zygomatic bone by lowering its volume and resistance. In addition, tumor spread is also facilitated by pneumatization finally resulting in temporomandibular joint (TMJ) ankylosis. So, recognizing the variations in the distribution of PAT and PRGF in different populations is imperative. Consequently, this study aimed to assess the prevalence of (PAT) and (PRGF) in the North- East Indian population by using CBCT.
| Materials and Methods|| |
This was a retrospective study carried out using the CBCT images of 500 patients who visited our institute; during 2018–2019. The sample size was calculated using OPEN Epi software.
Results from OpenEpi, Version 3, open-source calculator
Written informed consent was taken from every patient for the usage of scan data for research study purposes before the scans were taken. The study was carried out in accordance with the ethical principles of the Declaration of Helsinki. The study was approved by the Institutional Ethics Committee (HCDSH/IEC/2018/017 dated February 5, 2018). The samples comprised 500 subjects of either sex with age range 18–86 years and were selected based on simple random sampling. The CBCT scans of these patients were taken and 3D images of the area of interest (articular tubercle and the PRGF of temporal bone) on either side were recorded.
All the 3D images were taken using a large field of view (FOV). The dimension of large FOV is 61 mm × 78 mm (height × width). The inclusion criteria of the study were images obtained for implant planning, orthodontics, TMJ disorders, and maxillofacial pathologies (cysts or tumors). The exclusion criteria of the study were patients in which the zygomatic arch was not adequately seen for technical or anatomical reasons and cases with a history of maxillofacial trauma.
A Cranex 3D CBCT Machine (Soredex, version 5.2, PaloDEx Group Oy, Finland) was used to obtain the digital images with an image intensifier detector and the following parameters: 120 kvp, 8 mA, voxel size 0.25 mm3, and scan time 20s. 3D reconstructions were reformatted on the server Workstation (Dell Precision, Model T5810XL). On Demand 3D TM Dental software, version 5.2 (Cyber Med, Finland) was used.
All the images were displayed on Dell Monitor 21 inches under dim-light conditions. The CBCT scans were obtained and examined in all orthogonal planes with special emphasis on sagittal sections. All the images were evaluated for the pneumatization of articular eminence and PRGF.
PAT was recorded bilaterally when:
- There is a radiolucent defect in the articular tubercle.
- Extension of the defect through the articular tubercle beyond the zygomaticomaxillary suture.
- There is no cortical enlargement or destruction of zygoma seen.
PRGF was recorded bilaterally when the above-mentioned three characteristics were found on the PRGF above the condyle. Pneumatization for both PAT and PRGF was classified by locularity, that is, unilocular, multilocular, and laterality, that is, unilateral and bilateral.
Locularity is a radiolucent oval defect with well-defined bony borders noted on radiographic evaluation of the area of interest. A single radiolucent defect was considered as unilocular and multiple radiolucent defects were considered as multilocular [Figure 2], [Figure 3], [Figure 4], [Figure 5]. A total of 1000 zygomatic bones were analyzed. The prevalence of pneumatization by age, sex, laterality, and locularity was determined.
Data were analyzed by using Statistical Package for the Social Sciences (SPSS) software program, version 21 (IBM). Differences between variables were evaluated by the Chi-square test and analysis of variance. A value of P < 0.05 was considered statistically significant. The readings were recorded multiple times and were tested for reliability (0.957: test–retest reliability by Spearman's rank coefficient) and validity (Cronbach α = 0.78).
| Results|| |
A total of 500 scans were analyzed during this study. The mean age among subjects with pneumatization of articular eminence and the PRGF was determined to be 45.27 ± 18.00 years [Table 1].
The total study population comprised 258 (51.6%) men and 242 (48.4%) women. The prevalence of PAT was detected in (123) 24.6% of patients and PRGF was detected in (122) 24.4% of the patients.
According to laterality, the overall prevalence of unilateral cases of PAT was found to be 18.6%, whereas in bilateral cases the prevalence was found to be 6%.
The prevalence of unilateral cases of PRGF was 24.4%, whereas no bilateral cases were recorded as shown in [Table 2].
|Table 2: Prevalence of pneumatization cases by laterality and type on CBCT images|
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According to locularity, the prevalence of unilocular cases of PAT was 15.2%, whereas 15.4% of multilocular cases were found. Unilocular PRGF was observed in 20% of cases and multilocular in 4.4% of patients as shown in [Table 3]. In PAT, no significant difference was found between the unilocular and multilocular type, whereas in PRGF there was a significant difference (i.e. P < 0.002).
The gender-wise distribution of studied subjects according to the laterality of both types of pneumatizations is shown in [Table 4]. For men, the occurrence of PAT was recorded as 10% unilateral and 6% bilateral, respectively. In women, only 8% unilateral cases were found. There were no bilateral cases of PAT in women. In PRGF, a total of 16.2% unilateral cases were observed in men, whereas in women only 8.2% unilateral cases were observed. A significant difference was found in PAT and PRGF according to laterality when compared gender-wise (P < 0.05).
The distribution of PAT and PRGF according to locularity when compared gender wise is shown in [Table 5]. In men, the occurrence of unilocular PAT was recorded in 10.8% and 11.2% were multilocular cases. In women, unilocular PAT was recorded in 5.4% and 5.2% were multilocular cases. In men, the occurrence of unilocular PRGF was recorded in 12.6% and 4.8% multilocular cases. In women, unilocular PRGF was recorded in 6.2% and no multilocular case was recorded. No significant difference was observed between unilocular and multilocular PAT but the unilocular appearance was observed significantly more often than the multilocular type of PRGF. Significant differences were seen in PAT and PRGF according to laterally and locularity when compared gender-wise (P < 0.05) [Table 5].
| Discussion|| |
Diagnosis and treatment of edentulism have come a long way. Nowadays, dentists are using implants to restore the form and function of dentition. If multiple teeth are to be replaced and the amount of available bone is not adequate in the maxillary region, then the implants are placed in the zygomatic bone. Keeping this treatment modality in mind, it becomes imperative for the maxillofacial radiologist to recognize and report the various anatomical variations occurring in this region.
Pneumatization of articular eminence and PRGF is considered to be a normal anatomical variation occurring in the temporal bone cavity related to the periosteal activity. Numerous studies have focused on the pneumatization of the temporal bone in different populations.,,, The development of complete adult pneumatization can be divided into three stages: the infantile from birth to 2 years of age; the transitional from 2 to 5 years; and thereafter the adult. In the infantile stage, the mastoid undergoes gradual enlargement, with the migration of air cells toward the periphery. The air cells that vary in size and shape become more distinct with time because of the progressive calcification of their walls. Pneumatization ceases during the adult stage.
The prevalence of PAT as reported in several CT and CBCT studies is between 8% and 51%.,,,,, In our study, it was 24.6%. The current review of the literature reveals an average female-to-male ratio of 1.1:1. In this study, it was 1:1.8 for PAT and 1:1.9 for PRGF. The difference between women and men was statistically significant in this study, which was not consistent with the literature.,, This variation might be attributed to the geographical distribution and race of the study population. In our study, the mean age of occurrence was 45.2 years, which was similar to that of Buyuk et al. who recorded a mean age of 47.4 years (2018). Other studies reported similar results with few variations, that is, Hoffmann et al. recorded 43.2 years (2001), Carters et al. observed 49.6 years (1999), Orhan et al. recorded 36.6 years (2005), Khojastepour et al. recorded 30.31 years, and Lacin et al. recorded 40.38 years (2019).
The age range of patients was 18–86 years, which is similar to Orhan et al. study (11–90) years and Tyndall and Matteson's study (15–74) years. In our study, the youngest patient reported with PAT was 35 years and PRGF was 18 years. Current literature revealed that the unilateral-to-bilateral ratios for PAT cases were 1:1.3, 3:1, and 1.2:1.,, In this study, the ratio was 3.1:1 for PAT cases. In our study, the unilateral-to-bilateral ratio for PRGF was 24.4 as no bilateral cases of PRGF were found.
The prevalence of PAT unilateral cases was found to be more during this study, that is, 18.6%. The prevalence of PRGF unilateral and unilocular cases recorded was also more in this study that is, 24.4%. The prevalence of left side pneumatization was significantly higher than that of the right side, which could be due to demographic variations, which is similar to a study of Ladeira et al. These differences and propensity toward the left side may be related to the etiologic factors for the occurrence of the pneumatizations. Resonance, minimization of the skull mass, air reservoir action, acoustic dissipation, and protection from external violence are some of the functional implications for temporal pneumatization. Allam suggested certain factors that may control the growth pattern such as mucous membrane condition, hereditary, growth center development in the bone, Eustachian tube function, and intercurrent infections, but the exact etiology remains unclear.
The prevalence of PRGF in Ladeira et al.'s study was found to be 0.02% of unilocular cases and 23% of multilocular cases, Buyuk et al.'s study found 2.9% unilocular cases and 26.7% of multilocular cases, and Salli et al.'s study found 14.7% unilocular cases and 47.1% multilocular cases. In this study, we found 20% of unilocular cases and 4.4% of multilocular cases, which is not consistent with the literature due to hereditary factors or the genetic pool from which this study sample was taken.
The prevalence of PAT in the study by Tyndall and Mattenson found 15 multilocular and 17 unilocular PAT cases, Orhan et al. reported 16 multilocular and 10 unilocular cases, and Yavuz et al. detected 66 multilocular and 44 unilocular PAT cases in their studies. In our study, we found 77 cases of multilocular PAT and 76 cases of unilocular PAT, which was more than several other studies.
PAT and PRGF do not require treatment. However, it is necessary to differentiate them from other radiolucent bony lesions during radiographic examinations. The differential diagnosis of PAT and PRGF includes aneurysmal bone cyst, osseous hemangioma, chondroblastoma, fibrous dysplasia, giant cell tumor, eosinophilic granuloma, and metastatic tumor. It should be kept in mind that PAT and PRGF have nonexpansile and nondestructive characteristics.,, TMJ has been associated with an acute temporal bone fracture. Zygomatic implants are contraindicated in cases of PAT. Hence, we can conclude that whenever a zygomatic implant is planned in the present population, the presence of pneumatization should always be kept in mind while planning surgical treatment.
Limitations and future prospects
This study is limited by its small sample size. Another fact that may have led to the increased finding of PAT and PRGF is the inclusion of the patients who had some TMD complaints and had been advised of the scans. Further studies with larger sample size and including healthy TMJ are advised.
| Conclusion|| |
In our study, the prevalence of PAT was 24.6% and PRGF was 24.4%. CBCT images are very useful for the detection of PAT and PRGF. A maxillofacial radiologist should be aware of zygomatic air cells or pneumatization in the related region during routine radiological investigations and during the planning of zygomatic implant placement. The preoperative temporal bone CBCT is a crucial component of the evaluation of PAT in a patient candidate for surgical intervention of TMJ.
Declaration of patient consent
The authors certify that necessary written informed consent was taken from the patients for the usage of scan data for research purposes and subsequent publishing of their scans/images with the journal. Every effort has been made by the authors to keep the images and scan data anonymized.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]