Is the panoramic radiography sufficient for detecting the relationship of the posterior maxillary teeth with maxillary sinus floor? A retrospective study comparative with cone-beam computed tomography

Fatma Busra Dogan; Bilgün Çetin; Faruk Akgünlü

doi:10.4103/ijhas.IJHAS_281_20

ORIGINAL ARTICLE

Year : 2021 | Volume : 10 | Issue : 2 | Page : 123-128

Is the panoramic radiography sufficient for detecting the relationship of the posterior maxillary teeth with maxillary sinus floor? A retrospective study comparative with cone-beam computed tomography

Fatma Busra Dogan¹, Bilgün Çetin², Faruk Akgünlü³
¹ Department of Oral and Maxillofacial Radiology, Konya Oral and Dental Health Hospital, Konya, Turkey
² Department of Oral and Maxillofacial Radiology, Faculty of Dentistry, Burdur Mehmet Akif Ersoy University, Burdur, Turkey
³ Department of Oral and Maxillofacial Radiology, Faculty of Dentistry, Selçuk Universty, Konya, Turkey

Date of Submission	28-Dec-2020
Date of Decision	10-Feb-2021
Date of Acceptance	21-Mar-2021
Date of Web Publication	18-May-2021

Correspondence Address:
Dr. Fatma Busra Dogan
Department of Oral and Maxillofacial Radiology, Konya Oral and Dental Health Hospital
Turkey

Source of Support: None, Conflict of Interest: None

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DOI: 10.4103/ijhas.IJHAS_281_20

Abstract

BACKGROUND: The topographical description of the relationship between the upper posterior roots and the maxillary sinus is essential for decreasing the risk of complications during surgical or nonsurgical procedures and to detect possible sinus pathologies. For the evaluation, the most commonly used imaging method is panoramic radiography. This study aims to investigate the reliability of panoramic radiography according to cone-beam computed tomography (CBCT), which is extremely successful in the three-dimensional evaluation, by examining the relationship between the maxillary teeth and the sinus floor.
MATERIALS AND METHODS: A total of 350 teeth were analyzed according to their topographic relationship to the maxillary sinus using panoramic and CBCT images. Two parameters were used to evaluate the safety of the panoramic radiograph on the posterior maxillary region. First, the topographic relationship was classified according to the criteria organized by Shahbazian et al. and compared both the imaging methods by the McNemar–Bowker test. Then, the diagnostic reliability test was performed for panoramic radiography according to the topographic classification. Second, 248 linear vertical measurements were made between the apexes of the roots and the sinus floor in the maxillary posterior region and then compared between the panoramic and the CBCT images.
RESULTS: The McNemar–Bowker test showed that there was a significant relationship between the two imaging methods in both the dental groups (premolar teeth P = 0.030 and molar teeth P = 0.014). Furthermore, a total of 124 measurements were analyzed using the Mann–Whitney U-test and no statistically significant difference was found between the two imaging methods (P = 0.576).
CONCLUSION: Although reliable results were obtained in panoramic radiographs when compared to CBCT images, panoramic radiography may not be sufficient before the surgical procedure. Nevertheless, when the posterior maxillary teeth are not too close to the sinus floor, panoramic radiographs can be used safely for the initial diagnostic evaluation.

Keywords: Cone-beam computed tomography, maxillary sinus, oral surgery, panoramic radiography

How to cite this article:
Dogan FB, Çetin B, Akgünlü F. Is the panoramic radiography sufficient for detecting the relationship of the posterior maxillary teeth with maxillary sinus floor? A retrospective study comparative with cone-beam computed tomography. Int J Health Allied Sci 2021;10:123-8

How to cite this URL:
Dogan FB, Çetin B, Akgünlü F. Is the panoramic radiography sufficient for detecting the relationship of the posterior maxillary teeth with maxillary sinus floor? A retrospective study comparative with cone-beam computed tomography. Int J Health Allied Sci [serial online] 2021 [cited 2023 Sep 27];10:123-8. Available from: https://www.ijhas.in/text.asp?2021/10/2/123/316293

Introduction

The maxillary sinus is an important anatomical structure that develops first in all paranasal sinuses and stops growing with the eruption of the third molars at approximately 20 years of age.^[1] The topographic relation of the inferior wall of the maxillary sinus with the maxillary root apexes varies according to an individual's age and size, the degree of pneumatization of the maxillary sinus, and the state of dental retention.^[2] The adult sinus is variable in its extension. Often, the floor of the maxillary sinus moves inferiorly and becomes close to the maxillary teeth,^[3] thereby creating a “hillock” (elevation of the sinus floor) or protrusions of root apexes into the sinus. In these cases, the bone thickness of the sinus floor is significantly reduced. Although the roots are protruded into the sinus radiographically, the actual perforation rate in histological sections is 14%–28%.^[4]

The topographical description of the inferior wall of the maxillary sinus and the relationship between the upper posterior roots and the maxillary sinus is essential for decreasing the risk of complications during surgical or nonsurgical procedures, endodontic treatment, and orthodontic movement of teeth.^[5] Especially in dental implant applications which have recently increased, it is important to evaluate the bone structure and anatomical structures in this region when planning the treatment before surgery. Besides, there are cases of maxillary sinusitis as a result of infections of these teeth or after dental procedures. It is reported that dental maxillary sinusitis is between 10%–12%.^[6] At this point, besides the clinical examination findings, radiographic evaluations come to the forefront to determine the relationship between the posterior teeth and maxillary sinus.^[7]

The maxillary posterior region can be evaluated by various radiographic techniques, including two-dimensional techniques, such as panoramic and intraoral radiography, and three-dimensional techniques such as cone-beam computed tomography (CBCT). Intraoral radiographs have some limitations in the posterior maxillary region to evaluate due to superimposition and limited imaging field.^[8] The most commonly used imaging method is panoramic radiography, which allows the visualization of many anatomical features with relatively low radiation dose and wide availability. American Academy of Oral and Maxillofacial Radiology recommends panoramic radiography in preimplant surgery, especially for the first diagnostic evaluation. However, horizontal and vertical magnification, the superposition of anatomical structures, and a lack of cross-sectional information are the disadvantages of this imaging modality.^[1],[7] CBCT imaging provides an accurate evaluation of the bone quality and quantity in the posterior maxillary region without the magnification and superimposition caused by teeth and the surrounding structures. In addition, cross-sectional images that provide buccolingual evaluation are useful in many diagnostic dental applications, especially implant planning.^[8],[9]

It is important to get the initial signals of the relationship between the tooth root and the sinus floor on radiological images. Although CBCT is such an advantageous imaging method as mentioned above, it is generally used on selected patients. Panoramic radiographs are easier to reach and cheaper.^[2] Therefore, the aim of this study is to evaluate the reliability of panoramic radiography compared with that of CBCT, which is accepted as the gold standard for three-dimensional imaging in the maxillofacial region, by assessing the relationship between the roots of posterior maxillary teeth and the sinus floor.

Material and Methods

The Ethics Committee of the Selcuk University, Faculty of Dentistry approved this study by protocol number: 2019/01.The study material comprised 55 individuals' CBCT images and panoramic radiographs obtained from the archives of the Department of Oral and Maxillofacial Radiology, Dentistry Faculty, S University. The CBCT images were acquired due to required additional detailed radiographic information, such as dental implant planning, determination of the impacted tooth position, and evaluation of pathological lesions. The inclusion criteria covered patients who were older than 20 years, had visible imaging of the posterior maxillary teeth and the maxillary sinus floor, patients needed to have fully erupted maxillary premolars/molars, and had both panoramic and CBCT imaging with a maximum interval of 2 months. Cases with maxillary bony pathology and teeth with periapical lesions were excluded from the study.

The panoramic exposures were made using a Carestream Kodak 8000 (Panoramic System Health Inc., Rochester, NY, USA) that was operated at 60 kV and 4 mA. Vertical measurements on panoramic radiographs were performed with the software ImageJ. The images were calibrated with the help of a known object's size before evaluation to prevent measurement inaccuracies due to magnification. The CBCT images were obtained using an Instrumentarium Dental (Palo DEx Group Oy, Nahkelantie, Tuusula, Finland). The acquisition parameters for the CBCT images were 89 kV and 4–12 mA, and the slice thickness was 0.5 mm. Multiplanar reconstruction was performed according to these parameters. Axial, sagittal, coronal, cross-sectional, and paraxial CBCT slices and panoramic views were examined by two oral and maxillofacial radiology specialists individually and independently.

A total of 350 teeth were analyzed according to their topographic relationship to the maxillary sinus using panoramic radiographs and CBCT images. Two parameters were used to evaluate the safety of the panoramic radiograph on the posterior maxillary region. First, the topographic relationship between the posterior maxillary teeth and the sinus floor was classified according to the following criteria, which were organized by Shahbazian et al.:

There is a distinct distance between the root apexes and the sinus floor (>0.5 mm distance)
The roots are in close contact with the floor of the maxillary sinus (<0.5 mm distance)
The roots are projected onto the sinus but are in fact lateral or medial to it
The roots are protruded into the maxillary sinus cavity.^[8]

For assessing the topographic relationship, a single score was obtained for each tooth and the two imaging modalities. In multi-rooted teeth, scoring was performed for the root that was most closely associated with the maxillary sinus [Figure 1].

Figure 1: Images with scores of 0, 1, 2, and 3 show the relationship between the maxillary posterior teeth and the maxillary sinus floor in panoramic images (a) and cone-beam computed tomography cross-sectional images (b). (0-a and 0-b show first molar, 1-a and 1-b show first premolar, 2-a and 2-b show first molar, 3-a and 3-b show first molar)

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Second, linear vertical measurements were made between the apexes of the roots and the sinus floor in the maxillary posterior region and then compared between the panoramic radiographs and CBCT images. A total of 248 vertical measurements were first performed on the panoramic radiographs where the relationship between the apexes and sinus floor was seen clearly, and these measurements were compared with those in the CBCT images. With the aid of the multiplanar evaluation of the CBCT images, the closest distance between the apexes and the sinus floor was determined and the measurements were performed on cross-sectional sections [Figure 2].

Figure 2: The image on the left shows the vertical distance between the maxillary sinus floor and the palatal root of the first molar on panoramic radiography and the image on the right shows the same root on cone-beam computed tomography cross-sectional image

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Statistical analysis

Statistical analyses were performed using the program Statistical Package for the Social Sciences SPSS version 22 (IBM Corp., New York, NY; formerly SPSS Inc., Chicago, IL, USA). All data were analyzed primarily descriptively. The topographic relationship of the maxillary sinus floor and the posterior maxillary teeth was evaluated by two oral and maxillofacial radiology specialists. The agreement between the two observers was evaluated by Cohen's kappa coefficient (panoramic radiographs = 0.756 and CBCT images = 0.921). According to McHugh ML's article, the kappa result can be interpreted as follows: values of ≤0: indicate a mismatch and between 0.01 and 0.20: none to mild, 0.21–0.40: fair, 0.41–0.60: medium, 0.61–0.80: significant, and 0.81–1.00: almost perfect agreement.^[10] Since significant and almost perfect agreements were observed, statistical analysis of the data was performed after consensus was made on different data. Vertical measurements were evaluated by the same observer twice at 3-week interval and a high correlation between measurements was found in the interclass correlation coefficient (ICC) (panoramic radiography ICC = 0.988 and CBCT ICC = 0.987). Comparison of the topographic relationship between the two imaging methods was analyzed by the McNemar–Bowker test, and comparison of vertical measurements was analyzed by the Mann–Whitney U-test. P ˂ 0.05 significance level was used for the analysis. Furthermore, CBCT was considered as a gold standard and “positive predictive value,” “negative predictive value,” and “diagnostic value (DV)” were calculated for the panoramic radiography.

Results

A total of 178 molar teeth and 172 premolar teeth were evaluated in terms of classification in 55 patients. The number of teeth classified according to topographic classification in this study is shown in [Figure 3] and [Figure 4]. The comparison of the classification between panoramic radiography and CBCT according to the McNemar–Bowker test result is shown in [Table 1] and [Table 2]. Premolar and molar teeth were compared separately within their dental groups, and the McNemar–Bowker analysis showed that there was a significant relationship between the two imaging methods in both the dental groups (premolar teeth P = 0.014 and molar teeth P = 0.030).

Figure 3: Bar chart showing the number of premolar teeth in the two imaging methods according to topographic classification (OPG: Panoramic radiography, cone-beam computed tomography)

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Figure 4: Bar chart showing the number of molar teeth in the two imaging methods according to topographic classification (OPG: Panoramic radiography, cone-beam computed tomography)

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Table 1: Agreements of maxillary premolar teeth roots in panoramic radiography and CBCT images according to the topographic categories

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Table 2: Agreements of maxillary molar teeth roots in panoramic radiography and CBCT images according to the topographic categories

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In comparison for premolar teeth, 95.5% of panoramic radiographs for class 0 showed the same classification as CBCT images. While this value was 54.2% for class 1, it was 73.3% for class 2. Furthermore, premolar teeth protruding into the sinus were not detected on both panoramic radiographs and CBCT images. When the classification of the molar teeth was compared for the two imaging methods, panoramic radiographs were found to be 75%, 76.2%, 73.1%, and 69% compatible with CBCT images for the classes 0, 1, 2, and 3, respectively.

In the topographic classification, the positive predictivity (PP), the negative predictivity, and the DV of the panoramic radiography were calculated [Table 3]. Accordingly, detecting the presence of the distant relationship between the sinus floor and the teeth (class 0) was a very high rate (PP = 0.92); however, it was quite sufficient for other classes as well (minimum PP = 0.64). On the other hand, the minimum calculated negative predictive value was 0.58 when there is no class 2 between the root tip and the sinus floor, the panoramic radiography has a relatively low probability to predict there is no class 2. In addition, the accuracy of the panoramic radiography was found to be quite sufficient as the DV calculated for all categories was between 0.83 and 0.93.

Table 3: According to CBCT gold standard diagnostic reliability test results for panoramic radiography

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The shortest vertical distances between the roots of the posterior maxillary teeth and the sinus floor were measured and descriptive analyzes of these measurements are shown in [Table 4]. In the comparison of vertical measurements, since the high correlation was observed in the ICC, the two measurements' mean values were used. While the minimum, maximum, and average values measured on panoramic radiographs were 0.7, 12.27, and 3.62 mm, respectively, these values were 0.6, 10.79, and 3.34 mm in CBCT images. A total of 124 vertical measurements were analyzed using the Mann–Whitney U-test and no statistically significant difference was found between the two imaging methods (P = 0.576).

Table 4: Descriptive values of vertical measurements (N: number, Min: minimum, Max: maximum Std : standard)

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Discussion

In this study, the relationship between the sinus floor and the maxillary posterior teeth was evaluated and CBCT images and panoramic radiographs were compared. First, the topographic relationship between the sinus floor and the teeth was examined using Shahbazian classification scores. This scoring method has the advantages of allowing a detailed evaluation of both premolar teeth and molar teeth and can be used in both the imaging methods.^[8] Second, linear measurements in the maxillary posterior region were compared with CBCT images. In their study, Zarch et al. stated that when the patient's head position is adjusted correctly, it is possible to obtain approximate exact measurements from panoramic radiographs for the posterior regions of the jaws.^[11]

Analysis of the topographic relationship with premolar teeth and sinus floor showed that a high correlation was found between the two imaging methods for class 0 (95.5%). For class 2, this value is 73.3%, while for class 1 it is 54.2%. Sharan and Madjar compared the two imaging methods according to their scoring methods and found that class 0, which is a significant distance between the sinus and teeth, was highly compatible (86%–96%).^[1] Panoramic radiography provides enough information for the presurgical evaluation of roots that are distant from the maxillary sinus, like what Sharan and Madjar expressed in their study.^[1] In the present study, it is seen that while class 2 is compatible with the two imaging methods, the percentage of compliance for class 1 decreases although there is no statistical difference. Class 1 indicates that the maxillary sinus is in contact with the posterior teeth and it was thought that this value decreased in panoramic radiography due to superposition connected to the lateral wall of the maxillary sinus.

When the topographic relationship of maxillary molar teeth with the sinus floor was compared, the classifications numbered 0, 1, 2 and 3 were 75%, 76%, 73% and 69%, respectively. which means that there is a certain distance between the sinus and teeth, similar to the premolar teeth groups in molar teeth, which is seen to be compatible with both the imaging methods. Lopes et al., in their study using the scoring method that was used in this study, reported that agreement was high in the classification of the first and second molar teeth whose roots were protruded into the sinus (84%, 63%, respectively) in both the imaging modalities.^[2] Freisfeld et al. reported that out of 129 roots, 64 determined to penetrate the maxillary sinus on the panoramic radiographs, but 37 roots showed penetration computed tomography (CT).^[12] The fact that panoramic radiography does not give information in the buccolingual direction explains that there are studies with different results in the literature. Moreover, the complex root morphology of molar teeth is a factor that makes evaluation difficult.^[13] In their study, Shahbazian et al. concluded that there was more agreement between the two imaging methods in molar teeth than in premolar teeth.^[8] Although there was not much difference in this study, better results were obtained in the region of molar teeth than premolar teeth. The reason for this is thought to be the superposition of the lateral wall of the maxillary sinus with the second premolar tooth, as already mentioned. Nevertheless, the studies in the literature and this study showed that the topographic evaluation of maxillary molar teeth with the sinus floor in panoramic radiography is relatively successful.^{[1[,[2],[12],[13]}

The present study also investigated that vertical distances between maxillary teeth and sinus floor were evaluated on panoramic radiographs and CBCT images. In this study, although the measurements on panoramic radiographs were longer than the CBCT images, there was no statistically significant difference between them. In a study investigating the reliability of vertical measurements on CBCT, it was stated that it is possible to perform the vertical measurements on the radiograph taken in the ideal position, with a confidence interval of 1 mm, and in the study, they concluded that vertical measurements on the CBCT showed clinically acceptable success.^[14] In their study, Sharan and Madjar measured the vertical distance that protruded the maxillary molar teeth into the sinus on panoramic radiographs and reported it was 2.1 times longer than CBCT.^[1] Considering the fact that panoramic radiography is not always possible in the ideal position, and superposition and magnification factors are considered, evaluation with a panoramic radiograph may not be sufficient in surgical procedures planned in the region near the sinus floor.^[2],[15]

Even tough there are various disadvantages of panoramic views, it is widely used today due to its advantages such as easy accessibility, evaluation of maxilla and mandible on a single image, low cost and low radiation dose. Although panoramic radiography images give good results in terms of vertical measurements, they cannot provide any information about buccolingual width. The most effective method for buccolingual evaluation is CBCT images and it contains a very low radiation dose compared to CT.^[16],[17]

Conclusion

In the current study, although reliable results were obtained in panoramic radiography when compared to CBCT images, it may not be sufficient for procedures that require detailed knowledge of the region's anatomy, especially before the surgical procedure. Nevertheless, when the posterior maxillary teeth are not too close to the sinus floor, panoramic radiography can be used safely to evaluate this region, especially for the initial diagnostic evaluation and it can be useful to measure linear vertical distances in the maxillary posterior region as long as it is taken by correct head positioning.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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