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| ORIGINAL RESEARCH |
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| Year : 2022 | Volume
: 14
| Issue : 3 | Page : 306-315 |
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Assessment of proximity of the maxillary premolars roots to the maxillary sinus floor in a sample of Egyptian population using CBCT: An observational cross-sectional study
Esraa K Morsy, Sahar H El Dessouky, Enas A Abdel Ghafar
Oral and Maxillofacial Radiology, Faculty of Dentistry, Cairo University, Cairo, Egypt
| Date of Submission | 26-Dec-2021 |
| Date of Decision | 14-Mar-2022 |
| Date of Acceptance | 14-Mar-2022 |
| Date of Web Publication | 28-Jun-2022 |
Correspondence Address:
Dr. Esraa K Morsy
11 Saraya Street, El Manial, Cairo
Egypt
 Source of Support: None, Conflict of Interest: None  | Check |
DOI: 10.4103/jioh.jioh_355_21
Aim: This research was conducted to assess the relationship between permanent maxillary premolar root apices and the maxillary sinus floor (MSF) in a sample of Egyptian population using cone beam computed tomography (CBCT). Materials and Methods: In this observational cross-sectional study, 128 CBCT scans were coded and recruited using simple random sampling method. A total of 216 upper first premolars and 232 upper second premolars were examined, according to the eligibility criteria. The scans were displayed using Planmeca Romexis® Viewer software, where image analysis was performed on corrected axial, coronal, and sagittal images. Gender of the patient was registered for each scan. The proximity between the maxillary premolars roots and the maxillary sinus floor (MSF) was determined according to Kilic et al.’s 2010 classification. The difference between the prevalence of different sinus relations in males and females was recorded, and correlation between right and left sides was determined. Categorical data were presented as frequency and percentage values and were analyzed using Fisher’s exact test and χ2 followed by multiple pairwise comparisons utilizing multiple z-tests with Bonferroni correction. The significance level was set at P < 0.05 within all tests. Results: The maxillary first premolars showed higher percentages for “No relation,” followed by type 3 than type 2. In contrast, type 2 was the most prevalent sinus relation in maxillary second premolars, followed by type 3. Conclusion: In a sample of the Egyptian population, most of the maxillary first premolars had no relation to the MSF. On the contrary, most of the maxillary second premolars were positioned much closer to the MSF where they recorded the highest percentage for type 2 sinus relation (roots contact sinus). In most cases, the palatal roots were closely related to the MSF than buccal ones in all maxillary premolars. Keywords: CBCT, Maxillary Premolars, Maxillary Sinus Floor, Relation
How to cite this article:
Morsy EK, El Dessouky SH, Abdel Ghafar EA. Assessment of proximity of the maxillary premolars roots to the maxillary sinus floor in a sample of Egyptian population using CBCT: An observational cross-sectional study. J Int Oral Health 2022;14:306-15 |
How to cite this URL:
Morsy EK, El Dessouky SH, Abdel Ghafar EA. Assessment of proximity of the maxillary premolars roots to the maxillary sinus floor in a sample of Egyptian population using CBCT: An observational cross-sectional study. J Int Oral Health [serial online] 2022 [cited 2023 Oct 5];14:306-15. Available from: https://www.jioh.org/text.asp?2022/14/3/306/348421 |
| Introduction | |  |
The close anatomical relationship between the maxillary premolar roots and the maxillary sinus floor (MSF) renders this anatomical region susceptible to morbid situations resulting from various dental interventions. The closer the roots to the sinus floor, the higher the probability of spread of odontogenic infection to the maxillary sinus causing inflammatory changes of its mucosal lining and bringing about maxillary sinusitis.[1],[2] It has been documented in literature that the maxillary premolars, especially the first ones, are frequently extracted during orthodontic treatment in cases with teeth crowding and protrusions.[3] However, these teeth, especially the endodontically treated ones, have the highest incidence of root fracture during extraction.[4] Hence, care should be taken to avoid perforation of the MSF during surgical extraction procedures which may lead to oroantral communication.
Two-dimensional imaging represented in periapical and panoramic imaging was the commonly used modality to evaluate this relation.[5] However, panoramic radiography suffers a lot of limitations such as loss of sharpness, superimpositions, and the unequal magnification, which reduce its reliability for such assessment.[6] Three-dimensional imaging represented mainly in cone beam computed tomography (CBCT) was introduced; these drawbacks have been overridden.
CBCT has revolutionized the diagnosis in the oral and maxillofacial region bringing about many merits to any study, such as high-resolution isotropic images, lack of superimposition, three-dimensional capabilities, and low radiation dose in comparison to CT.[7],[8] CBCT also was proved to be an accurate and reliable technique in the assessment of the relationship of maxillary posterior teeth to the MSF.[9],[10]
There were limited studies conducted to assess the proximity of the maxillary premolars roots to the MSF in Egyptian population, in which most of the published researches were directed to the maxillary molars only.[2],[11] This triggered the urge to conduct our study to reduce the complications and potential risks resulting from violation of the MSF with sinus involvement during various dental interventions in the maxillary premolars.
| Materials and Methods | | |
Study design and population
This is a retrospective cross-sectional study that was approved by the Research Ethics Committee, Faculty of Dentistry, Cairo University. A total of 216 upper first premolars and 232 upper second premolars were examined from 128 CBCT scans of 68 male and 60 female Egyptian patients with the mean age of 37 years. The number of maxillary first premolars roots was 383, whereas the maxillary second premolars roots was 292. CBCT scans were collected from the database available at the Oral and Maxillofacial Radiology Department, Faculty of Dentistry, Cairo University, Egypt. They were taken as a part of the patients’ dental examination, diagnosis, or treatment planning during the period from 2018 to 2020. The age, gender, and the nationality of the patients were documented in the available database, so we were sure that all the assessed scans were for Egyptian patients.
Sample size calculation
Sample size calculation was performed using Epi Info 7.2.2.2. Based on the results of a previous study by Fry et al.,[12] with alpha (α) level of 5%, acceptable margin of error of 2%, and the power 80%, the minimum estimated sample size was 128 subjects. The sample size calculation was approved by the Medical Biostatics Unit, Faculty of Dentistry, Cairo University, Cairo, Egypt on July 6, 2019.
Sampling and addressing potential sources of bias
The sample was collected and assessed from September 2019 till May 2021. Using the simple random sampling method, 128 CBCT scans were coded and recruited in the study. The key of coding was done by one of the authors and concealed from the two observers who assessed the targeted relation. Also, the age, name, and gender of all scans were concealed by the same author prior to scans interpretation by the observers.
Sampling criteria
Inclusion criteria were patients’ age should be above 18 years and premolars with intact and completely formed roots. Exclusion criteria were CBCT images of poor quality or artifacts interfering with assessment of the proximity of the maxillary premolars roots to the MSF. Criteria were presence of cystic or neoplastic lesions in the posterior area of the maxilla and/or maxillary sinus and presence of signs of previous surgery in the maxillary sinus. Furthermore, maxillary premolars with developmental anomalies, external or internal root resorption, evidence of apicectomy or periapical surgery were excluded as these may hinder the accurate assessment of the targeted relation.
Image acquisition and analysis
The selected CBCT scans were all performed using the Planmeca ProMax® 3D Mid (Planmeca OY, Helsinki, Finland) CBCT machine. All CBCT images were acquired using 90 kVp, 6–8 mA, 12–13.6 s, 200 μm voxel size, and a field of view 4 × 5 or 16 × 10 cm. The CBCT images were then imported to Planmeca Romexis® Viewer (Romexis version 4.5.0.R; Planmeca OY) for image viewing and analysis.
CBCT-corrected sagittal and coronal images were created by adjusting both sagittal and coronal reference lines to be passing parallel to the long axis of the root under investigation and through its center; then these images were used for assessment of the relation of premolars root tips to the MSF. Further confirmation of the assessed relationship was gained from the corrected CBCT axial cut after adjusting the axial reference line to pass through the most apical part of the root on both coronal and sagittal images [Figure 1]. | Figure 1: (a) Adjustment of the sagittal line with the long axis of the root on coronal cut, (b) adjustment of the coronal line with the long axis of the root on sagittal cut, (c) corrected axial cut confirming type 1 sinus relation
Click here to view |
Images were analyzed to observe the following variables:
Assessment of the relationship between the maxillary premolars roots and the MSF was based on a classification proposed by Kilic et al.,[13] who suggested three types for the targeted relationship [Figure 2].
Type 1: representing root penetrating MSF [Figure 3]. | Figure 3: CBCT scan of double-rooted upper right 5 showing (a) coronal, (b) sagittal, and (c) corrected axial cuts displaying upper right 5 with both buccal (red arrow) and palatal (blue arrow) roots penetrating the sinus floor (type 1 sinus relation)
Click here to view |
Type 2: representing root contacting MSF [Figure 4]. | Figure 4: (a) adjustment of the sagittal line to pass through the long axis of the palatal root. (b) Adjustment of the coronal line on sagittal cut to pass through the long axis of the palatal root. (c) Corrected axial cut confirming type 2 sinus relation
Click here to view |
Type 3: representing root extending below MSF [Figure 5]. | Figure 5: CBCT scan of upper right 5 showing (a) coronal and (b) sagittal cuts displaying type 3 sinus relation (red arrow)
Click here to view |
When the MSF did not appear above the root apex (the apex is not related to the MSF but it is related to the floor of the nasal cavity), the case was described as “No relation” [Figure 6]. | Figure 6: CBCT (a) coronal and (b) sagittal cuts displaying upper right 4 with both buccal (red arrows) and palatal (blue arrow) roots having no relation to the sinus floor
Click here to view |
- A The effect of gender as a confounder on different sinus relations was assessed.
- B Correlation between right and left sides was determined.
Blinding and inter- and intra-observer agreement
Images were assessed twice by an investigator EKM having 6 years of experience in CBCT interpretation with 1-month interval between the two reading sessions to assess the intra-observer reliability. While for the inter-observer reliability, 50% of the images were analyzed once more by a second investigator having 13 years of experience in the same field. Blinding was assured by scans coding and concealing the patients’ demographic data from both observers.
Statistical analysis
Statistical analysis was performed with IBM SPSS Statistics for Windows, Version 23.0 (IBM Corp., Armonk, NY, USA). Quantitative data were presented as frequencies and percentages. χ2, Fisher’s exact, Wilcoxon signed-rank, and McNemar’s tests were used for comparisons and associations related to qualitative data. Kappa statistic was used to assess intra- and inter-observer agreement. Kappa statistic values were interpreted as follows: 0–0.2: weak agreement, >0.2–0.4: fair agreement, >0.4–0.6: moderate agreement, >0.6–0.8: good agreement, >0.8–0.99: very good agreement, while a value of 1 indicates perfect agreement. The significance level was set at P ≤ 0.05.
| Results | | |
The present study was conducted on 128 subjects: 68 males (53.1%) and 60 females (46.9%). The mean (SD) value for age was 37 (13.9) years, with a minimum of 18 and a maximum of 68 years. The study included 107 upper right first premolars, 109 upper left first premolars, 116 upper right second premolars, and 116 upper left second premolars.
There was very good inter- and intra-rater agreement between different observations with kappa values ranging from 0.811 to 0.889.
Regarding the statistical analysis of the relation of the premolar root apices to the MSF
•In the maxillary first premolars
The highest prevalence among maxillary first premolars (single-, double-, and triple-rooted) was attributed to “No relation,” whereas type 3 sinus relation recorded the second position followed by type 2 and finally type 1 that was observed in only one single-rooted upper first premolar. Palatal roots showed higher prevalence for types 2 and 3 than buccal ones [Table 1]. | Table 1: Descriptive statistics for the relation between upper first premolars roots apices and the MSF
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•In the maxillary second premolars
Type 2 sinus relation showed the highest prevalence among the single- and double-rooted teeth followed by type 3. “No relation” recorded the third position in single-rooted maxillary second premolars and buccal roots of double-rooted ones followed by type 1, whereas for palatal roots type 1 showed higher prevalence than “No relation” [Table 2]. | Table 2: Descriptive statistics for the relation between upper second premolars roots apices and the MSF
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The association between maxillary sinus relation and number of roots presented in [Table 3] showed that for the first upper premolar, the association was statistically significant (χ2=13.08, P = 0.037) with the percentage of double-rooted teeth [214 (70.9%)] with no maxillary sinus relation being significantly higher than that of single-rooted teeth [30 (52.6%)] (P < 0.05). For upper second premolars, the association was not statistically significant (χ2=7.65, P = 0.201). | Table 3: Association between maxillary sinus relation and number of roots of maxillary premolars
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Regarding the effect of gender as a confounder on different types of sinus relation
We used χ2 and Fisher’s exact tests for the association between gender and upper premolars roots relation with the sinus floor and we found that in upper first premolars, there was no statistically significant association between them [Table 4].
While for upper second premolars, there was a statistically significant association between gender and roots relation with the sinus in single-rooted teeth (P-value = 0.019, effect size = 0.240). Males showed higher prevalence of type 1, type 2, and “No relation” than females who showed higher prevalence of type 3. There was no statistically significant association between gender and roots relation with the MSF regarding double-rooted teeth [Table 5]. | Table 4: Descriptive statistics and results of χ2 and Fisher’s exact tests for the association between gender and upper first premolar roots relation with the sinus
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 | Table 5: Descriptive statistics and results of χ2 and Fisher’s exact tests for the association between gender and upper second premolar roots relation with the sinus
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Regarding the effect of the side on the sinus–root relation
Results of the association between maxillary sinus relation and tested side presented in [Table 6] showed that for the first upper and second premolars, the association was not statistically significant (P > 0.05). There was a high degree of concordance between the right and left sides in both premolars for different types of sinus relation.
| Discussion | | |
The maxillary sinus is directly implicated in several dental practices.[14] Not surprisingly, surgical and endodontical procedures increase the risk of sinus complications which might be traumatic, time-consuming, and costly for the patient. So prior knowledge of the appropriate relation between the maxillary posteriors and the MSF is necessary. For this reason, the current study was conducted aiming to assess the proximity of the premolars roots to the MSF using CBCT images in a sample of Egyptian population.
CBCT was the modality selected in this study, as it was proven by many previous studies to be the gold standard of assessing sinus–root relation.[15],[16],[17]
Retrospective concept in our study was meant to get CBCT scans that were already done earlier for different purposes to avoid exposing the patients to unneeded radiation dose for the research purpose. CBCT scans of patients above 18 years were included to ensure complete skeletal development of the maxillary sinus.[18] This study involved only fully erupted maxillary premolars with intact roots to ensure accurate evaluation of the targeted relationship; moreover, we excluded premolars with developmental anomalies, root resorption, apicectomy, and presence of an apical or sinus pathosis as these may hinder the accurate assessment of the roots proximity to the MSF as recommended by Ok et al.,[19] Gu et al.,[20] and Shaul Hameed et al.[21] Assessment of the proximity of both buccal and palatal root apices of the maxillary premolars to the MSF was performed based on a classification postulated by Kilic et al.[13] This classification was also used by several investigators such as Ok et al.[19] on Turkish population, Gu et al.[20] on Chinese population, and Fuentes et al.[22] and Kaushik et al.[23] on Indian population. CBCT images were analyzed in the corrected axial, coronal, and sagittal planes as recommended by von Arx et al.[14] and Anter et al.[2]
Our results showed that most of the maxillary first premolars (single-, double-, and triple-rooted) exhibited “No relation” to the MSF, whereas type 3 sinus relation (roots below the MSF) recorded the second position followed by type 2 (roots contacting the MSF) and finally type 1 (roots penetrating MSF) that was observed in only one single-rooted upper first premolar. This could be attributed to the fact that most of the first premolars are positioned close to the radiographic inverted Y-shape of Ennis where the MSF curves upward to intersect with the lateral wall of the nasal cavity. Additionally, the cortical thickness of the MSF is greatest at the maxillary first premolars region. Estrela et al.[24] conducted their study on Brazilian population and Nino-Barrera et al.[25] on Colombian population.
While for the maxillary second premolars, type 2 sinus relation (roots contacting MSF) showed the highest prevalence among the single- and double-rooted second premolars followed by type 3 (roots below the MSF). “No relation” recorded the third rank in single-rooted maxillary second premolars and buccal roots of double-rooted ones followed by type 1 (roots penetrating MSF), whereas for their palatal roots, type 1 (roots penetrating MSF) showed higher prevalence than “No relation.”
In accordance with our results, von Arx et al.[14] who conducted their study on Swish population reported that first premolars were further from the MSF than the second ones and that palatal roots of premolars were closer to the sinus floor than the buccal ones, a finding that was further supported by Kilic et al.[13] Similarly, they concluded that the frequency of premolars root protrusion into the maxillary sinus (type 1) was very low in first premolars but higher in second premolars.
Partial agreement was found between our results and those of Fuentes et al.,[22] where, similar to our results, they reported that type 1 (roots penetrating MSF) recorded the least frequency in the first premolars, whereas “No relation” was the least prevalent relation in the second premolars. But disagreeing with our results, they reported that type 3 (roots below MSF) was the most prevalent sinus relation in both first and second premolars with 55.5% followed by type 2 (19%), then “No relation,” and only 10% of cases exhibited type 1 sinus relation (roots penetrating MSF). This difference between their results and ours may be due to the difference in the number of patients included in their studies, their gender distribution, their age ranges, and the ethnicity characteristics.
Similar to our results, Ok et al.[19] who conducted their study on Turkish population reported that most maxillary first premolars had no relationship with the MSF and only 1.2% exhibited type 1 sinus relation. However, some disagreements were found between their results and ours in the prevalence of different types of sinus relations in maxillary second premolars as they concluded that type 3 sinus relation (roots below MSF) was most frequently observed (72%) in these teeth, followed by type 2 (roots contacting MSF) 20% and type 1 (roots penetrating MSF) 8%, which was contradicting our results as type 2 showed the highest incidence among the second premolars in our study.
Several studies were found in the literature evaluating the relation of maxillary posterior teeth to the MSF, such as Shokri et al.[26] (Iranian population), Bulut et al.[27] (Turkish population), Amato et al.[28] (Italian population), Gu et al.[20] (Chinese population), Razumova et al.,[29] Chan et al.,[30] and Kaushik et al.[23] All of these investigators concluded that type 3 (roots below MSF) was the most dominant position for both premolars followed by type 2 (roots contacting MSF) and then type 1 (roots penetrating MSF) which was much higher in the second premolars than the first ones. It is worth mentioning that there was inconsistency in their methodology as they reported type 3, whether the apex was below or had “No relation” to the MSF and this explains the reason behind their conclusions that type 3 was the most dominant sinus relation. Furthermore, some of them did not assess the relation between buccal and palatal roots tips separately to the MSF (Shokri et al.,[26] Amato et al.,[28] Gu et al.,[20] and Chan et al.[30]).
Odd results were reported by Nino-Barrera et al.[25] who concluded that the buccal roots of both bicuspids showed higher incidence of penetrating the MSF than the palatal one. However, revising their methodology we found that they classified the targeted relation into two types only (type 1 representing roots below the sinus and type 2 for roots penetrating the sinus) and they did not consider any other relation of the roots apices to the MSF.
Our results showed that there was association between gender and sinus relation only in the second premolars, where males showed a higher prevalence for type 1 and 2 sinus relations than females. This may be due to the fact that most of the first premolars had no relation with the MSF and that the average root length is greater in males than in females as reported by Kim et al.[31] and Abozeid et al.[32] so higher probabilities of close sinus relations were found in males. Similarly, Shokri et al.[26] reported that protrusion of the roots inside the sinus (type1) was more common in males than in females. Contradicting ours and Shokri et al.’s[26] results, Kilic et al.,[13] Von Arx et al.,[14] and Gu et al.[20] found no significant difference between males and females in both premolars, whereas Ok et al.[19] reported that only in the maxillary first premolars males showed a higher prevalence for type 1 (roots penetrating MSF) and type 2 (roots contacting MSF) sinus relations.
Our results showed that there was a high degree of concordance between the right and left sides in both premolars for different types of sinus relation. This was confirmed by Kilic et al.,[13] Ok et al.,[19] Shokri et al.,[26] Von Arx et al.,[14] and Kumar et al.,[33] who reported that no significant differences were found between the left and right sides in cases of both first and second premolars.
Limitations
The limitations were that the root apices of upper first premolars in some cases were positioned at the location of the inverted Y-shape of Ennis which rendered the assessment of the sinus relation type controversial. The curvature of the examined roots required the adjustment of the reference lines to pass with long axis of the root in several planes several times for accurate assessment of MSF relation. All the sample was taken from a single study center.
| Conclusion | | |
- 1. In a sample of the Egyptian population, maxillary first premolars rarely exhibit close relation to the MSF, in contrast to the maxillary second premolars. In both premolars, palatal roots are closer to the sinus floor than buccal roots.
- 2. Association between gender and roots proximity to the MSF was found in maxillary second bicuspids only, where males showed a higher incidence of contacting and penetrating the MSF than females.
- 3. High degree of symmetry was found between right and left premolars in different types of sinus relations.
Recommendations
- 1. Dental practitioners should assess the proximity of the maxillary premolars to the MSF prior to any dental procedures to avoid intra- or post-operative complications that would lead to oroantral communication and possible spread of infection to the maxillary sinus.
- 2. Further studies with larger sample size of Egyptian population from different study centers should be conducted considering all the maxillary posterior teeth (premolars and molars) for comparison and more comprehensive results.
- 3. Further studies should be conducted to assess the influence of age on different types of sinus relations.
Acknowledgements
The authors would like to thank Dr Bassam Ahmed Abulnoor for his statistical guidance.
Financial support and sponsorship
This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.
Conflicts of interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Authors’ contribution
EKM: Conceived and designed the study, sample collection, data entry, interpretation of data, drafting the manuscript, approval of the final manuscript. EAA: Contributed to study design, data interpretation, revising the drafted manuscript, approval of the final manuscript. SHE: Coding the data, contributed to data analysis, revising the drafted manuscript, approval of the final manuscript.
Ethical policy and Institutional Review Board statement
The current study was approved by the Ethics Committee of the Faculty of Dentistry, Cairo University, Egypt (approval number 19-7-78) (approval date July 28, 2019) and complies with the Declaration of Helsinki (2013). The trial is registered on clinicaltrials.gov under identifier: NCT04018352 (https://clinicaltrials.gov/ct2/show/NCT04018352).
Patient declaration of consent
Not applicable.
Data availability statement
The data that support the findings of this study are available from the corresponding author, EKM, upon reasonable request.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6]
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