| Abstract|| |
Introduction: The purpose of the study is to assess the vertical and horizontal relationship between the roots of maxillary posterior teeth and neighboring structures like the floor of the maxillary sinus and cortical plates using cone-beam computed tomography (CBCT). Method and Materials: 100 CBCT scans of the patients from the Indian population were analyzed. Vertical and horizontal relationship between the roots of maxillary posterior teeth and the floor of the maxillary sinus was divided into 4 types and 3 types, respectively. Distances between the root apices and the floor of the maxillary sinus and cortical plate was measured for each root and results were formulated. Results: In total 365 teeth were assessed, 185 first molar and 180 second molar. It was found that the roots of first molar and second molar usually had type 2 (root apices in close contact with the floor of maxillary sinus) and type 3 (roots projecting laterally into the sinus, but its apices are outside the sinus border) vertical relationship respectively with the floor of maxillary sinus. The deepest portion of the floor of the maxillary sinus was most commonly seen projecting between buccal and palatal roots. The mean distance between the cortical plate and root was highest for the distobuccal root of second molar i.e., 1.20 mm SD = 0.97. Conclusion: The distobuccal root of the first molar and mesiobuccal root of the second molar are closest to the sinus floor, hence clinician should be extra cautious while working on these roots during endodontic or surgical procedures in the Indian population.
Keywords: Cone Beam Computed Tomography, Maxillary sinus, Molars
|How to cite this article:|
Goyal SN, Karjodkar FR, Sansare K, Saalim M, Sharma S. Proximity of the roots of maxillary posterior teeth to the floor of maxillary sinus and cortical plate: A cone-beam computed tomography assessment. Indian J Dent Res 2020;31:911-5
|How to cite this URL:|
Goyal SN, Karjodkar FR, Sansare K, Saalim M, Sharma S. Proximity of the roots of maxillary posterior teeth to the floor of maxillary sinus and cortical plate: A cone-beam computed tomography assessment. Indian J Dent Res [serial online] 2020 [cited 2021 Apr 15];31:911-5. Available from: https://www.ijdr.in/text.asp?2020/31/6/911/311666
| Introduction|| |
The close relationship between root apices of the maxillary posterior teeth and the floor of the maxillary sinus, makes maxillary sinus an anatomic structure of primary concern during dental practice in the maxillary posterior region. Close approximation between the root apices and the floor of the maxillary sinus can lead to untoward complications during extractions, endodontic procedures and implant placement in the region. Well-studied complications like formation of oro-antral fistula, displacement of the root apex into the sinus cavity during extractions,,, root filling materials getting pushed into the sinus during root canal treatment are likely. It is also observed that the longer the roots of molar extending into the sinus cavity as seen on the orthopantomograph pre-extraction; the more is the pneumatization and expansion of the sinus cavity following extraction in the region, thus causing a reduction in the available bone height and width for implant placement after extraction. The estimated width of the alveolar bone covering the roots in the coronal third and the middle third regions of the roots greatly influences the extraction procedure and post-operative implant placement. The relationship between the root apices of maxillary molars and adjacent anatomical structures has been studied in different populations and found to be varying between different races and populations of the world.
Cone-beam computed tomographic (CBCT) imaging is a modern boon, which is contrary to conventional imaging, provides with precise 3D images in reasonable radiation dose and cost-effective way, eliminating distortion and superimposition of anatomic structures over the region of interest.
The purpose of this study was to investigate the vertical and horizontal relationship between the roots of the maxillary molars and the adjacent anatomical structures like maxillary sinus and cortical plate using cone-beam computed tomography (CBCT) in the Indian population. In the present study, the distance between the roots of the maxillary molars and sinus floor and also the thickness of the bone between the root and the alveolar cortical plate is measured in the coronal section. The effort is made with the thought to create a strong knowledge base for the clinicians to refer when deciding surgical technique and prognosis while working on maxillary molars in the Indian population in areas where there is no easy accessibility to the CBCT due to location or cost.
| Materials and Methods|| |
This study was approved by the local institutional ethical committee. Out of total 500 CBCT scans obtained from computer database, 100 CBCT scans consisting of 365 teeth were included in the study based on the inclusion and exclusion criteria. These CBCT images were taken for the study of any pathology or anatomical structures like the position of impacted third molars, to study root canal anatomy and temporomandibular joint disorders. The retrospective analysis of the CBCT scan ensured no additional radiation exposure to the patient for this study. The inclusion criteria consisted of (i) completely erupted all maxillary posterior teeth inside of the arch or both the arches i.e first premolar, second premolar, first molar, second molar and third molar. Patients with missing posterior teeth or with pathology such as tumors, cysts and carcinoma in the maxillary posterior region were excluded from the study.
CBCT examination was performed using a KODAK 9000C 3D unit (Carestream Health Inc., 150 Veronal Street, Rochester, NY 14608, USA). Operating parameters of the unit were: 10 ma, 74 kvp, 5 × 3.7 cm field of view (FOV) was 200 micrometers resolution. Image acquisition time 32.4 sec, 3 stitched volumes were used for the study. The equivalent dose from the study was around 38 micro sv per quadrant. The acquired data was reconstructed with a 0.2 mm section interval and thickness. All the images were acquired in the Digital Image Communication in Medicine (DICOM) format and evaluated using the Kodak Dental Imaging Software (KDIS).
Two oral radiologists were appointed as observers for this study. Both the observers had a minimum of 3 years' experience in evaluating and reporting CBCT scans. For the study, the scans were reviewed by both the observers independently on a HP Compaq LE 1911 24-inch nonglossy monitor 1,920 × 1,200 resolution, with a DICOM Workstation using KDIS. Also each scan was viewed in curved, oblique and orthogonal slicing view as an additional view in the KDIS. Each scan was viewed in axial, coronal and sagittal sections. Measurements were done in the coronal section oblique slicing. If there was a disagreement on the diagnosis, a consensus was reached after a discussion between the two observers. The observers were not aware of the aim of the study.
Observers were allowed to use magnification, modify screen brightness and contrast and the other tools for evaluating the CBCT scans. The observers could scroll and view all sections in sagittal, coronal and axial planes.
- Vertical Relationship between the floor of the maxillary sinus and root tips of maxillary posterior teeth were assessed as follows:
- The distance of each root of the maxillary first molar and second molar from the floor of the maxillary sinus was measured on a CBCT cross-sectional image.
- Measurements were made by depositing one reference dot at the radiographic root apex and the other at the floor of the maxillary sinus at a point along the long axis of the root of the teeth. The vertical distance was measured for each root of the first molar and second molar. Values were displayed to the nearest 0.1 mm. For the purpose of the data analysis, apices extending above the floor were assigned negative value and those below were assigned positive values.
- The vertical relationship of each tooth with the maxillary sinus was classified into four types of CBCT cross-sectional images [Figure 1].
|Figure 1: Vertical relationship between the maxillary posterior teeth root tips and floor of maxillary sinus and (a) Type 0, (b) Type 1, (c) Type 2, (d) Type 3|
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- Type 0- The root not in contact with the cortical border of maxillary sinus.
- Type 1-The root in contact with the cortical borders of the sinus.
- Type 2-The root projecting laterally into the sinus, but its apex was outside the sinus borders.
- Type 3- The root apex projecting into the sinus cavity.
The horizontal relationship between the floor of the maxillary sinus and root tips of maxillary posterior were assessed as follows [Figure 2].
|Figure 2: Horizontal relationship between the maxillary posterior teeth root tips and floor of maxillary sinus (a) Type B, (b) Type BP, (c) Type P|
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- The horizontal relationship between the roots of the teeth and the sinus floor was classified into 3 types
- Type B- The lowest point on the sinus floor located onto the buccal side i.e., buccal to the buccal root
- Type BP- the lowest point of maxillary sinus located between the buccal and palatal roots.
- Type P- The lowest point of the sinus located on the palatal side of the palatal root.
Width of alveolar bone between the roots of maxillary posterior teeth and the alveolar cortical plate was measured as follows [Figure 3].
|Figure 3: Distance between the roots of maxillary posterior teeth and respective cortical plate. (a) distance between buccal root and buccal cortical plate (b) distance between palatal root and palatal cortical plate|
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- The distance between the buccal roots and the buccal cortical plate and palatal root from the palatal cortical plate was measured at the level below bifurcation in the CBCT cross- sectional images coronal section.
Descriptive and inferential statistical analyses were carried out in the present study. Results on continuous measurements were presented on mean ± SD and results on categorical measurements were presented in Number (%). The level of significance was fixed at P = 0.05 and any value less than or equal to 0.05 was considered to be statistically significant.
Student t-tests (two tailed, unpaired) was used to find the significance of study parameters on a continuous scale between two groups. Analysis of variance (ANOVA) was used to find the significance of study parameters among three or more groups.
The Statistical software IBM SPSS statistics 20.0 (IBM Corporation, Armonk, NY, USA) was used for the analyses of the data and Microsoft word and Excel were used to generate graphs, tables etc.
| Results|| |
A total of 100 CBCT scans were included in the study. The mean age of participants was 41 years ± 17 years. Out of 100 scans, 44 scans were of female and 56 were of male. The vertical and horizontal distance between the root apices of molar and adjacent structures was found to be statistically insignificant among genders.
Total 185 first molar (93 right first molar +92 left first molar) and 180 second molar (91 left first molar +89 left second molar) were studied. No statistically significant difference between the vertical and horizontal distance between root apices of molar and adjacent structures were observed between the right and left sides of the arch.
The vertical relationship between root apices of maxillary molars and the floor of maxillary sinus is expressed in [Table 1].
|Table 1: Vertical relationship between the roots of maxillary posterior teeth root tips and floor of maxillary sinus|
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The difference in the vertical relationship among mesiobuccal, distobuccal and palatal roots of first molar was statistically highly significant, whereas for second molar the difference was not significant.
The horizontal relationship between the roots of maxillary molars and the floor of maxillary sinus is expressed in [Table 2].
|Table 2: Horizontal relationship between maxillary posterior teeth root tips and floor of maxillary sinus|
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The mean distance of the roots of maxillary molars with the adjacent cortical plate is expressed in [Table 3]; and was found to be statistically highly significant between first and second molar for all three roots (mesiobuccal, distobuccal and palatal).
|Table 3: Mean distance (in mm) between roots of maxillary posterior teeth and respective cortical plates|
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| Discussion|| |
This study provides in-detail information regarding the relationship of roots of maxillary posterior teeth with adjacent structures in the Indian population. Studying the literature we observed vast differences in the findings among different races of the world. This could be attributed to the maxillofacial anatomical differences in different parts of the world. The minimum age of the patient included in the study was 22 years, as the down growth of mandible continues till around the second decade of life. The thickness of the alveolar bone between the root apex and the respective cortical plate holds importance as it influences the spread of odontogenic space infections. Determining the width of the alveolar bone greatly influences the implant placement procedures in the given region. This study provides with a complete understanding of the vertical and horizontal relationship of the roots of maxillary molars with the anatomical structures i.e floor of the maxillary sinus and cortical plates, which hold prime importance and can influence surgical and endodontic procedures in the maxillary posterior region.
In the Indian population, statistically we observed no significant difference (P > 0.05) between the relationship of root apices of molars and adjacent structures among genders in the Indian population. However, on reviewing the literature we identified that the findings on other races were contrary to our findings. In the Turkish, Iranian and Korean population it was found that males were more susceptible to the undesirable results while working on maxillary molars owing to the close proximity of the roots of the maxillary molars to the floor of the maxillary sinus.
In the Indian population, among molars of the maxillary right and left arch, no statistically significant difference (P > 0.05) was observed in the distance between the roots of the maxillary molars and adjacent structures. This was in accordance with the findings in the Korean, Turkish and Iranian population.
Considering the vertical relationship for the roots of first molar it was observed that distobuccal and palatal root were frequently seen to have type 2 relationship with the floor of maxillary sinus i.e projecting laterally along the sinus cavity; whereas mesiobuccal root was found to have type 1 relationship more frequently i.e in contact with the floor of the maxillary sinus. It was calculated that 47.9% of the maxillary first molar has more than one root having type 2 vertical relationship with the floor of the maxillary sinus in the Indian population. For the second molar, all three roots i.e., mesiobuccal, distobuccal and palatal were frequently seen to be in close contact (type 1) with the floor of the maxillary sinus. In the Indian population it was observed, 48.8% of the maxillary second molar has more than one root having type 1 vertical relationship with the floor of the maxillary sinus. The findings of our study differed from the study conducted in other populations of the world in which it was observed that the roots of the molars mostly protrude into the maxillary sinus., However, results of our study were consistent with the findings in the Turkish population. Comparing the mean distance in mm for the roots with type O relationship with floor of maxillary sinus it was observed that the distobuccal root of maxillary first molar and mesiobuccal root of the second molar were closest to the floor of the maxillary sinus. This finding in the Indian population, is in accordance with a study previously performed on other populations of the different race, in which the authors measured the distance from the root apex to the maxillary sinus floor (MSF), providing evidence that the second molar mesiobuccal root was the closest one to the sinus floor by its mean value.,,,,,
In the present study, it was observed that the deepest part of maxillary sinus most commonly lies between buccal and palatal roots for both the first and second molar with P value more than 0.05 [Table 2]. This was the common finding in all populations on which the studies were conducted in this regard and literature was available.
We also observed that in Indian population, the thickness of the alveolar bone between the roots of the posterior teeth and the their respective cortical plate at below furcation level intended to increase as we moved posteriorly into the arch [Table 3], with the figures being statistically highly significant (P < 0.001). The mean distance was least for the mesiobuccal root of first molar (0.29 mm) and highest for the distobuccal root (1.20 mm) of second molar [Table 3]. For individual molar, the covering of alveolar bone was found to be more around buccal roots as compared to the palatal roots. This could be explained based on the hypothesis that as the palatal cortical plate is thicker than the buccal cortical plate, the alveolar bone is less around palatal root compared to buccal roots. This finding in the Indian population was in accordance with the study conducted on the Korean population with similar specifications with the present study.
| Conclusions|| |
The conclusions we withdraw from the study were:
- In the Indian population, the distobuccal root of the first molar and mesiobuccal root of the second molar are frequently at a minimum distance from floor of the maxillary sinus, hence clinician should be extra careful while working on these two roots during the endodontic and surgical procedure.
- In the Indian population, the thickness of the alveolar bone between the roots and cortical plate increases posteriorly into the arch; being thicker for buccal roots compared to the palatal root.
- Indian males and females are equally susceptible to untoward complications during surgical and endodontic procedures in the maxillary posterior region owing to similar relationships of the roots of maxillary molar with the adjacent structures.
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Conflicts of interest
There are no conflicts of interest.
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Dr. Shikha N Goyal
Department of Oral Medicine and Radiology, Nair Hospital Dental College, Mumbai - 400 008, Maharashtra
Source of Support: None, Conflict of Interest: None
[Figure 1], [Figure 2], [Figure 3]
[Table 1], [Table 2], [Table 3]