|Year : 2015 | Volume
| Issue : 2 | Page : 194-197
Comparison of panoramic radiograph with cone-beam computed tomography in assessment of maxillary sinus floor and nasal floor
Vijay Kumar Bokkasam1, Pavani Muddepalli1, Raviraj Jayam1, Sathish Babu Devaki1, Aruna Pakerla2, Sridevi Koduri3
1 Department of Oral Medicine and Radiology, CKS Theja Institute of Dental Sciences and Research, Tirupathi, Andhra Pradesh, India
2 Department of Dental Surgery, ACSR Government Medical College, Nellore, Andhra Pradesh, India
3 Faculty of Dental Sciences, SGT University, Gurgaon, Haryana, India
|Date of Submission||23-Dec-2014|
|Date of Acceptance||12-Oct-2015|
|Date of Web Publication||21-Nov-2015|
Department of Oral Medicine and Radiology, CKS Theja Institute of Dental sciences and Research, Chadalawada Nagar, Renigunta Road, Tirupati - 517 506, Andhra Pradesh
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Introduction: Panoramic radiograph is frequently prescribed by dentists for implant planning and, hence, accurate assessment of anatomical structures in panoramic radiograph is of utmost importance. Aims: The aim of the present study is to know the accuracy of panoramic radiograph in assessment of relationship between maxillary sinus floor and posterior teeth roots, and the distance from alveolar crest to nasal floor by comparing it with that of cone-beam computed tomographic (CBCT) image. Materials and Methods: Panoramic and CBCT images of 30 patients were analyzed. The topographic relationship of each root of posterior teeth to the maxillary sinus floor was evaluated and classified into three classes. The distance from the peak point on maxillary alveolar crest to nasal floor was measured in panoramic radiograph as well as in CBCT image. All the measurements were made by built-in measurement tools. Results: Class 1 roots in panoramic radiograph showed high agreement (86%) with CBCT image, followed by class 0 (76%). There was a significant difference in the measurements of alveolar bone height (ABH) in the nasal floor region with a P value of 0.018. Conclusion: Panoramic radiograph is reliable in assessment of nasal floor and maxillary sinus, provided position of the patient, distortion, and the inherent magnification factor are taken into consideration.
Keywords: Alveolar bone height, CBCT, nasal floor, panoramic radiograph, sinus floor
|How to cite this article:|
Bokkasam VK, Muddepalli P, Jayam R, Devaki SB, Pakerla A, Koduri S. Comparison of panoramic radiograph with cone-beam computed tomography in assessment of maxillary sinus floor and nasal floor. J Indian Acad Oral Med Radiol 2015;27:194-7
|How to cite this URL:|
Bokkasam VK, Muddepalli P, Jayam R, Devaki SB, Pakerla A, Koduri S. Comparison of panoramic radiograph with cone-beam computed tomography in assessment of maxillary sinus floor and nasal floor. J Indian Acad Oral Med Radiol [serial online] 2015 [cited 2018 Nov 14];27:194-7. Available from: http://www.jiaomr.in/text.asp?2015/27/2/194/170136
| Introduction|| |
Panoramic radiography is often used in dental practices because it is readily available and provides a view of many structures of jaws at low cost and less radiation.  However, a panoramic radiograph is a two-dimensional image and accurate measurements are difficult to obtain because panoramic views produce a variable inherent magnification distortion, typically 20-30%. Assessment of alveolar bone, identification and location of mental foramen, nasal floor, and maxillary sinus are critical, particularly in presurgical implant planning. Furthermore, the adult sinus floor extends between adjacent teeth or between individual roots, creating elevations in the antral surface (hillocks) or protrusions of root apices into the sinus, in which case the thickness of the sinus floor is markedly reduced.  Hence, the aim of the study is to know the accuracy of panoramic radiograph in the assessment of relation between maxillary sinus floor and posterior teeth roots; and nasal floor.
| Materials and Methods|| |
The study material consisted of panoramic and cone-beam computed tomographic (CBCT) images of 30 patients obtained using Kodak 9000 3D system (Carestream Health, Inc., Rochester, NY, USA). The topographic relationship of each root of 15, 16, 17, 25, 26, and 27 to the maxillary sinus floor was evaluated and classified in panoramic radiograph and compared with that of CBCT images as follows [Figure 1]: Class 0 - there is no contact between maxillary posterior teeth roots and sinus floor; class 1 - sinus floor is in contact with maxillary posterior teeth roots; and class 2 - roots of maxillary posterior teeth project into the sinus. In case of class 0 and 2, the distance between the deepest point on the sinus floor and the tip of root apices was measured. In class 2, this distance was taken as the length of projection. The classification followed in the present study is a condensed classification proposed by Sharan and Madjar.  The distance from the peak point on maxillary alveolar crest to the nasal floor was measured in the panoramic radiograph and compared with that of the CBCT image [Figure 2]. When double image was seen in the panoramic radiograph, the lower image was considered as the nasal floor. 
|Figure 1: Classification of relation between the floor of maxillary sinus and posterior teeth roots|
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|Figure 2: Distance between the nasal floor and the alveolar crest on cropped panoramic radiograph|
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| Results|| |
Three hundred and eighty-eight roots of maxillary second premolar, first and second molars in 30 subjects were classified and measured. The number of teeth roots classified in the study is listed in [Table 1]. It was observed that 61.6% of all roots showed class 1 in panoramic radiograph, while 71.1% showed class 1 in the CBCT image. The change in the classification of roots in CBCT image from one class to the other in the panoramic radiograph is listed in [Table 2]. There was a significant change in the classification with chi-square value of 192.637 and P value of 0.000. There was a significant deviation of panoramic radiograph from the CBCT image in assessment of distance of alveolar crest to nasal floor with a P value of 0.018 as shown in [Table 3].
|Table 1: Total number of roots measured by classifi cation on CBCT images and panoramic radiograph|
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|Table 3: Mean distance from the crest of alveolar bone to the nasal floor|
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| Discussion|| |
The present study has been conducted to know the reliability of panoramic radiograph in clinical practice by comparing it with that of CBCT which is considered as standard. Most of the studies found only the relationship of floor of sinus to maxillary posterior teeth roots, ,,,, but did not specify the change in classification from one class to the other on different radiographs. Only one study showed change in the classification in panoramic radiograph and CBCT images.  The present study correlated the relationship of floor of sinus to maxillary posterior teeth roots, as well as change in classification, percentage of change and its significance in panoramic radiograph and also in the CBCT image.
In the present study, 72% of the cases showed the same classification in both the CBCT image and panoramic radiograph. 62.1% of class 0, 85.8% of class 1, and 21.1% of class 2 showed the same classification in both CBCT and panoramic radiographic images. Class 0 was most frequently observed in second premolar, class 1 in distobuccal and palatal roots of second molar, and class 2 in palatal root of first molar in panoramic radiographs and CBCT images. Also, 28% showed change in classification in panoramic radiograph; 37.89% of class 0, 25.72% of class 1, and 11.76% of class 2 in CBCT images showed change in classification from one class to the other on panoramic radiographs.
[Table 2] shows that there are 71 panoramic roots in class 2, of which only 15 were confirmed as class 2 in the CBCT images. It shows that 78.8% of roots have changed their classification, mostly to class 1 in the CBCT image. Also, 73.2% of class 2 panoramic roots are actually class 1 in CBCT images, showing protrusion of roots into the sinus on panoramic radiograph. Thus, it shows false protrusion of roots in to the sinus in the panoramic radiograph. 21.2% of roots that projected in to the sinus cavity in panoramic radiograph showed protrusion into the sinus in the CBCT images. The present study showed that the distobuccal root of second molar was closest to the floor of maxillary sinus, thus correlating with the results of other studies. ,, Kwak et al., in their study, showed that the apex of the distobuccal root of the second molar was closest to the inferior wall (average 2.74 mm) and the palatal root of the first premolar was farthest from the inferior wall of the maxillary sinus (average 6.27 mm). 
Nimigean et al. reported that the second molar had the most intimate antral relation, i.e., 93.9% of the second molars showed close relationship with the maxillary sinus floor.  The present study also showed that the second molar was closest to the sinus floor, of which 78.5% of distobuccal and palatal roots were closest to the sinus floor, and of all the teeth showing close relationship, the second molar represented 33.5%. Jung and Cho showed that the distance between the sinus floor and the root of the molar was shortest for the mesiobuccal roots of second molar and longest for the palatal roots of second molar.  The present study also showed that the mean distance of palatal root of second molar from the floor of sinus was longest, but it was shortest for distobuccal root rather than mesiobuccal root of the second molar.
In the present study, the mean distance of nasal floor from the crest of maxillary alveolar bone was 16.1 mm on panoramic radiograph and 17.02 mm on the CBCT image, showing a significant difference between CBCT and panoramic radiograph. The lower values of panoramic radiograph than CBCT may be due to difficulty in localizing the floor of nasal fossa on the panoramic radiograph. This could be probably due to patient positioning resulting in single/double image of various shapes like wide angle W, wide angle V, concave arc, or straight shape on panoramic radiograph, as reported by Damante et al.  According to Damante et al., when Frankfort plane is parallel to the floor, the most common image will be a wide angle W, wide angle V, concave arc, or straight shape. To our knowledge, there is no reference in the literature regarding the distance from crest of alveolar bone to nasal floor. There is only one study on the measurement of vertical length from the root tip of maxillary anterior teeth to the nasal floor, which was the study of Jang et al. 
| Conclusion|| |
The present study showed that there is high correlation between CBCT and panoramic radiograph in subjects with roots classified as class 1 (in contact with the floor of sinus). In these cases, two-dimensional panoramic images are sufficient to provide the clinician with information about the true relation between teeth roots and sinus. Panoramic radiograph is less reliable in assessment of distance between the crest of alveolar bone and the nasal floor, and CBCT is preferred over it.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2]
[Table 1], [Table 2], [Table 3]