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 Table of Contents  
Year : 2018  |  Volume : 30  |  Issue : 3  |  Page : 260-264

The relationship between the roots and furcation of the maxillary first molar to the maxillary sinus: A cone-beam computed tomography study

1 Department of Oral Medicine and Radiology, Al Badar Dental College and Hospital, Gulbarga, Karnataka, India
2 Department of Orthodontics, Al Badar Dental College and Hospital, Gulbarga, Karnataka, India

Date of Submission25-Jul-2018
Date of Acceptance26-Oct-2018
Date of Web Publication18-Oct-2018

Correspondence Address:
Dr. Syed Shahbaz
Department of Oral Medicine and Radiology, Al Badar Dental College and Hospital, Naganhalli Road, Gulbarga - 585 102, Karnataka
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/jiaomr.jiaomr_130_18

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Introduction: Pneumatization of maxillary sinus leads to posterior root displacement into the sinus cavity associated with potential complications following extraction of these teeth, or planning an implant in case of missing ones. Thus the relation of the maxillary sinus to the maxillary posterior teeth is of utmost importance. Hence the study was taken up to evaluate the relation of maxillary first molar to the maxillary sinus. Objectives: Assessing the relationships between the roots and furcation of the maxillary first molar to the floor of the maxillary sinus. Materials and Methods: A retrospective study where 50 CBCT scans of maxillary first molars of 36 patients were taken and the vertical relationship of the roots and furcation with the floor of the sinus were analyzed and classified. Results: Totally 14 (28%) mesio buccal roots, 8 (16%) disto buccal roots and 5 (10%) palatal roots were in Class 3, which is perforating into the sinus and total of 18 scans had furcations whose distance from the sinus floor was less than 5mm with Mean ± SD as 3.64 ± 1.14 and rest had more than 5mm with Mean ± SD as 6.19 ± 2.63 Conclusion: Our study concluded that though most roots were not in touch with the maxillary sinus, a notable amount were either in touch or penetrating into it. Thus any pathology assessment or treatment plan in the first molar region must be dealt with proper three dimensional images to understand the approximation of the sinus and plan out procedure best suited for the patient.

Keywords: Cone-beam computed tomography, furcation, maxillary first molar, maxillary sinus

How to cite this article:
Katti G, Shahbaz S, Katti C, Rahman MS. The relationship between the roots and furcation of the maxillary first molar to the maxillary sinus: A cone-beam computed tomography study. J Indian Acad Oral Med Radiol 2018;30:260-4

How to cite this URL:
Katti G, Shahbaz S, Katti C, Rahman MS. The relationship between the roots and furcation of the maxillary first molar to the maxillary sinus: A cone-beam computed tomography study. J Indian Acad Oral Med Radiol [serial online] 2018 [cited 2022 Nov 28];30:260-4. Available from: http://www.jiaomr.in/text.asp?2018/30/3/260/243651

   Introduction Top

The maxillary sinus is the first paranasal sinus to develop and ends growth at approximately 20 years of age.[1] Development of the maxillary sinus begins during fetal period and continues after birth. With the completion of the adult dentition eruption sequence, the maxillary sinus reaches its full development. The maxillary sinus is a pyramid-shaped bony cavity lined by the nasal antral wall at the base and its tip lying in the zygomatic bone, with an average volume of 15 cc.[2]

As per studies, a healthy maxillary sinus is aseptic in 80%–100% of the population with no presence of any bacteria or foreign material.[3],[4] The topography of the interior wall of maxillary sinus with maxillary root apices varies as per the individual's age, size, and degree of pneumatization of the maxillary sinus and the state of dental retention.[5]

The apices of the maxillary posterior teeth roots may protrude the sinus, therefore reducing the thickness of the sinus floor markedly. As the maxillary first molar is the first permanent tooth to erupt in the oral cavity and due to higher caries index is more prone to be extracted, the possibility of oro-antral communication after extraction is higher.[6] The projecting roots are usually separated from the sinus by various bony thickness, but in some its by the sinus mucosa alone. Thus, for various dental procedures such as extraction, orthodontic movements, apicectomies, and implant placements, proper relation of the maxillary first molar to the maxillary sinus is important. Various radiographic modalities can be used to see the relations of the maxillary first molar to the maxillary sinus such as Intra Oral Periapical Radiography (IOPAR) and Orthopantomography (OPG), but these being two-dimensional have their limitations. The floor of the maxillary sinus at some places creates elevations known as hillocks in antral surface extending between roots of adjacent teeth and also extending in between roots of same tooth.[7] In such scenarios, the best choice for imaging modality is the cone-beam computed tomography (CBCT) as it provides for crisp three-dimensional images without any anatomic overlaps.[8],[9]

Even though studies have been undertaken for evaluating relations of maxillary posterior teeth to that of the maxillary sinus, not many studies have been done in the Indian population. The objective of this undertaken study was to evaluate the various relations of the maxillary first molar to that of the maxillary sinus.

   Materials and Methods Top

A total sample of 50 CBCT scans of maxillary first molars from 36 patients were collected using NewTom® Giano CBCT machine with NNT software. The ethical clearance to conduct the study was obtained from Institutional Ethical Committee. Of the 36 patients, 18 belonged to female and 18 male patients who had got done the scans as routine investigations for various procedures. The mean age of the patients stand to be 36.54 years. Only samples that were free of any kind of pathology in the area of interest, which is the maxillary first molar, the maxillary sinus, and their vicinity, were taken up for the study. The scans were analyzed and measurements were done using the inbuilt tools in the software.

The roots of the samples were divided into four types, Type 0 to Type 3, where Type 0 meant those maxillary first molar roots that were not in contact with the sinus, Type 1 meant the roots were in contact with the sinus, Type 2 meant the roots encompassed the sinus, and Type 3 meant the roots were into the sinus [Figure 1]. If the types were 0 or 3, the vertical dimensions were measured which were then further classified into six groups based on the measurements. Group I: Type 1, Group II: 0–2 mm, Group III: 2.1–4 mm, Group IV: 4.1–6 mm, Group V: >6 mm, and Group VI: into the sinus. The vertical measurement of the maxillary first molar furcation and the sinus wall was taken and grouped as below 5 mm and beyond 5 mm.
Figure 1: Types of relationship between the roots of maxillary first molar to maxillary sinus on CBCT

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The scans were assessed in a well-lit room by a single observer, twice after a gap of 5 days to do away with any intraobserver ambiguity. It was then analyzed by Chi-square test to find out whether any significant differences are there among the groups. Statistical analysis was done using SPSS version 23.0 (IBM Corp, Armonk, NY, USA) and analysis of variance.

   Results Top

The study was conducted on 36 patients whose mean age was 36.94 ± 16.33 years. The minimum age of patient was 10 years and the maximum age was 72 years (range 10–72 years). There were 18 men and 18 women in the study. The study includes 27 maxillary right first molars and 23 maxillary left first molars. As per the availability of CBCT scans among 36 patients, 22 unilateral and 14 bilateral first molar teeth were studied. Thus, a total of 50 maxillary first molar were included in the study.

The frequency and prevalence of maxillary first molar tooth per class are charted out in [Table 1] and [Graph 1]. It is seen that Class 0 has the maximum number of roots, whereas Class 1 has the minimum. It also shows that mesiobuccal roots were the one which perforated the sinus the most. Group-wise distribution of the maxillary first molar roots per class is given in [Table 2]. The mean distances of each of the roots are given in [Table 3]. There was no statistically significant difference of means among different types of roots (mesiobuccal, distobuccal, and palatal) in Class 0, Class 1, and Class 3 with Class 2 having no vertical relation.
Table 1: Frequency and prevalence of first molar roots per class

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Table 2: Group-wise distribution of first molar roots per class

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Table 3: Vertical measures of-sinus floor mean distance per root class

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The relation of the furcation to the sinus is given in [Table 4], where it depicts the number of furcation relations having vertical relation of less than equal to 5 mm and more than that [Graph 2]. The maximum furcation–sinus distance was 14.2 mm and the minimum was 0.8 mm. The maximum number of maxillary first molar, 32 (64%), had more than 5 mm of furcation–sinus distance with a mean of 7.61 ± 2.11 mm and those remaining 18 (36%) had a mean of 3.64 ± 1.14 mm.
Table 4: Furcation-sinus floor mean distance

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   Discussion Top

The relationship of the maxillary sinus and the maxillary posterior teeth is an important one in terms of treatment planning in that region. The approximation of the maxillary posterior teeth roots to the antrum and pneumatization of the antrum are the major concerns. The maxillary first molar teeth are the first secondary teeth to erupt in the oral cavity; they are more prone to caries and pathologies. Hence, it is even more so important to know its relationship to that of the maxillary sinus.

This study was conducted to assess the anatomical relationship of roots of maxillary first molar to the floor of the maxillary sinus and distance between furcation and the sinus floor. It has been reported that the anatomical relationship between the root and the antrum might influence the oro-antral spread of infections originating in and around the maxillary molars.[10],[11],[12],[13] Hence, the relationship between these must be understood to help clinicians avoid any untoward situations while performing procedures in this area.

Certain cases have been reported of orbital abscess after Root canal treatment (RCT) of a maxillary first molar, caused by a rapid exacerbation of periapical inflammation.[10] When planning endodontic surgery of the first maxillary molar (e.g., apicoectomy), one should also take into consideration the oro-antral communication that may occur. It has been proven that conventional periapical radiographs cannot be used as predictors for perforation of the maxillary sinus during periapical surgery of maxillary premolars and molars.[11] The close proximity between the first molar roots and the floor of the sinus represents an issue not only for endodontic procedures but also for periodontal surgery and dental prosthetic therapy. Huang and Brunsvold[12] reported a case of maxillary sinusitis following the periodontal treatment of maxillary first molar, with deep pockets and major bony defects. There is a case report describing that after a maxillary molar extraction, the impression material was pushed into the antrum through an unseen oroantral fistula.[13]

In our study, we saw Class 0 to be the most prominent of the classes (42.6%) which was similar to as reported by Jung and Cho.[14] in their study. Class 0 was the most frequently observed in the palatal roots with almost half of them in Class 0. Class 2 was the most common in palatal roots as per Jung and Cho, but in our study we found out that it was almost equally distributed among palatal and distobuccal, 18 in each.[14]

Mesiobuccal roots were the one which penetrated the sinus floor most, with 36.8% of them penetrating, whereas only 25% of distobuccal root penetrated the sinus floor and 15.6% of the palatal root did so. Even in the studies compiled by Didilescu et al.[6] and Waite et al.,[2] the buccal roots penetrated the sinus floor the most. The mean distance between the sinus floor and the root apex was the shortest for the palatal roots (3.58 ± 2.05) which was again in accordance with the study by Didilescu et al. The mesiobuccal and distobuccal have means of 3.62 ± 2.01 and 3.62 ± 1.79, respectively.

As per Didilescu et al., a distance of more than 5 mm between furcation and the sinus floor is needed for an immediate implant placement to be done without any chances of perforation into the sinus.[6]

In our study, we found out that 18 teeth had the distance lower than 5 mm with a mean value of 3.64 ± 1.14 and 32 teeth with the distance of more than 5 mm with mean value 7.61 ± 2.11 which corresponds with a mean of 7.64 in the study done by Dididlescu et al.[6]

Thus, in our study it could be seen that though majorly the roots did not touch the sinus there were a substantial amount of them that either touched the sinus or penetrated into them and there were no significant difference among the roots as per their distance from the sinus, which means equal importance should be given to all of them as even a regular procedure such as root canal treatment can turn complicated if instruments get lodged or penetrate the sinus. Also in our study, it could be seen that the furcation to sinus distance is more than 5 mm for a majority of the teeth which makes them easy to be replaced by immediate implant loading in cases of extractions.

   Conclusion Top

Multiple factors affect the distance between the root tips of maxillary molar and the maxillary sinus floor and each patient needs to be evaluated individually. As observed in our study, in most cases it can be expected that the relation is a Class 0, that is, root tip not in contact with sinus; penetration was mostly restricted to the mesiobuccal roots. In Class 0, distribution was almost equal among Groups II, III, and IV. Almost two-thirds of the teeth had a furcation to sinus distance of more than 5 mm with a mean value of over 7 mm making it a good choice for clinicians to plan for immediate implant placements.

It is hoped that this study will help the clinicians in properly planning out treatment in areas near to the sinus floors, like apicoectomy or implant placements as they will get to know the various types of relations present between the molars and sinus floors which is prevalent in the subpopulation. The furcation depth will come in handy in case of immediate implant placements. Proper knowledge of the sinus and root relationships will also help in case of extraction of teeth in the molar region and evaluate the integrity of the sinus floor. In our study, the sample size was petite; extensive studies with larger sample size can throw more light into the varied relations of molars with the sinus floor.

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Conflicts of interest

There are no conflicts of interest.

   References Top

Sharan A, Madjar D. Correlation between maxillary sinus floor topography and related root position of posterior teeth using panoramic and cross-sectional computed tomography imaging. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2006;102:375-81.  Back to cited text no. 1
Waite DE. Maxillary sinus. Dent Clin North Am 1971;15:349-68.  Back to cited text no. 2
Lambrecht J, Böhlck I, Dierck P. The physiologically germ free maxillary sinus.Diseases of the antrum. Berlin, Germany: Springer; 1986. p. 31-7.  Back to cited text no. 3
Watzek G, Bernhart T, Ulm C. Complications of sinus perforations and their management in endodontics. Dent Clin North Am 1997;41:563-83.  Back to cited text no. 4
Laine F. Diagnostic imaging of the maxillary sinus. Oral Maxillofac Surg Clin North Am 1999;11:45-67.  Back to cited text no. 5
Didilescu A, Rusu M, Sandulescu M, Georgescu C, Ciuluvica R. Morphometric analysis of the relationships between the maxillary first molar and maxillary sinus floor. J Stomat 2012;2:352-7.  Back to cited text no. 6
Kilic C, Kamburoglu K, Yuksel SP, Ozen T. An assessment of the relationship between the maxillary sinus floor and the maxillary posterior teeth root tips using dental cone-beam computerized tomography. Eur J Dent 2010;4:462-7.  Back to cited text no. 7
Machado GL. CBCT imaging – A boon to orthodontics. Saudi Dent J 2015;27:12-21.  Back to cited text no. 8
Kamburoğlu K. Use of dentomaxillofacial cone beam computed tomography in dentistry. World J Radiol 2015;7:128-30.  Back to cited text no. 9
Koch F, Breil P, Marroquín BB, Gawehn J, Kunkel M. Abscess of the orbit arising 48 h after root canal treatment of a maxillary first molar. Int Endod J 2006;39:657-64.  Back to cited text no. 10
Oberli K, Bornstein MM, von Arx T. Periapical surgery and the maxillary sinus: Radiographic parameters for clinical outcome. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2007;103:848-53.  Back to cited text no. 11
Huang CH, Brunsvold MA. Maxillary sinusitis and periapical abscess following periodontal therapy: A case report using three-dimensional evaluation. J Periodontol 2006;77:129-34.  Back to cited text no. 12
Dimitrakopoulos I, Papadaki M. Foreign body in the maxillary sinus: Report of an unusual case. Quintessence Int 2008;39:698-701.  Back to cited text no. 13
Jung YH, Cho BH. Assessment of the relationship between the maxillary molars and adjacent structures using cone beam computed tomography. Imaging Sci Dent 2012;42:219-24.  Back to cited text no. 14


  [Figure 1]

  [Table 1], [Table 2], [Table 3], [Table 4]


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