|Year : 2020 | Volume
| Issue : 4 | Page : 526-530
|Impact of dental operating microscope, selective dentin removal and cone beam computed tomography on detection of second mesiobuccal canal in maxillary molars: A clinical study
Kuzhanchinathan Manigandan1, Periasamy Ravishankar2, Krishnamoorthy Sridevi2, Venkatesan Keerthi2, Prakash Prashanth2, Angambakkam Rajasekaran Pradeep Kumar2
1 Department of Conservative Dentistry and Endodontics, Faculty of Dental Sciences, Sri Ramachandra Institute of Higher Education and Research (Deemed to be University), Chennai, Tamil Nadu, India
2 Department of Conservative Dentistry and Endodontics, Thai Moogambigai Dental College and Hospital, Dr. MGR Educational and Research Institute (Deemed to be University), Chennai, Tamil Nadu, India
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|Date of Submission||11-Apr-2020|
|Date of Decision||29-Apr-2020|
|Date of Acceptance||29-May-2020|
|Date of Web Publication||16-Oct-2020|
| Abstract|| |
Introduction: Maxillary molars may frequently require root canal therapy and can have complex anatomy. It is important to locate and treat the second mesiobuccal canal to significantly improve prognosis. Aim of the Study: The purpose of this study was to evaluate direct vision, dental operating microscope (DOM), selective dentin removal under DOM, and cone beam computed tomography (CBCT) in clinical detection of second mesiobuccal root canal (MB2) in maxillary molars. Materials and Methods: A total of 122 maxillary first and second molars indicated for root canal treatment were included in our study. Following access cavity preparation, the presence of MB2 canal orifice was assessed in four stages. Stage I: with direct vision. Stage II: under DOM, Stage III: after selective dentin removal under DOM and Stage IV: teeth in which MB2 canal was not identified by Stage III were further investigated with CBCT. The number of canals identified during each stage was analyzed statistically. Results: Clinical detection of MB2 canal in our study was 90%, with 93% in maxillary first molar and 86% in maxillary second molar. 64% MB2 canals were located at Stage I (direct vision) which improved to 84% at Stage II (under DOM) and 90% at Stage III (selective dentin removal under DOM). CBCT investigation (Stage IV) further improved the identification of MB2 canal leading to overall prevalence of 93%. Conclusion: The results of our study demonstrated that MB2 canal can be clinically detected in up to 90% of maxillary molars by the use of DOM and selective dentin removal. CBCT investigation is indicated when MB2 canals are not clinically detected.
Keywords: Cone beam computed tomography, dental operating microscope, maxillary first molar, maxillary second molar, second mesiobuccal canal
|How to cite this article:|
Manigandan K, Ravishankar P, Sridevi K, Keerthi V, Prashanth P, Pradeep Kumar AR. Impact of dental operating microscope, selective dentin removal and cone beam computed tomography on detection of second mesiobuccal canal in maxillary molars: A clinical study. Indian J Dent Res 2020;31:526-30
|How to cite this URL:|
Manigandan K, Ravishankar P, Sridevi K, Keerthi V, Prashanth P, Pradeep Kumar AR. Impact of dental operating microscope, selective dentin removal and cone beam computed tomography on detection of second mesiobuccal canal in maxillary molars: A clinical study. Indian J Dent Res [serial online] 2020 [cited 2020 Oct 31];31:526-30. Available from: https://www.ijdr.in/text.asp?2020/31/4/526/298405
| Introduction|| |
Success of endodontic treatment depends upon thorough mechanical and chemical disinfection of the entire root-canal system. One of the major causes for root canal treatment failure is inability to detect and treat all canals of the root canal system.,
A thorough knowledge of root canal anatomy is essential for successful endodontic treatment outcome. Maxillary molars may frequently require endodontic therapy and can have complex root canal anatomy., Complexities in maxillary molar anatomy were first recognized by Walter Hess in 1925. Since then, anatomy of maxillary molars has been extensively studied.,,
The anatomical form of maxillary molar includes three roots namely mesiobuccal (MB), disto-buccal (DB), and palatal (P) having one canal each with a frequent variation being the presence of second mesiobuccal canal (MB2).[1.8,9] The frequency of MB2 canal has been reported to range from 18% to 95%., The prevalence of MB2 varies with the methods used in each study, such as clearing technique, sectioning, and radiography.,, Stropko in his clinical study reported that MB2 canals were located in 93% of maxillary first molars and 60% in maxillary second molars. A literature review of maxillary first molar by Cleghorn et al. stated that the incidence of MB2 canal was 56.8%. A recent systematic review and meta-analysis has demonstrated a 70% prevalence of MB2 root canals in maxillary first molar and 39% in maxillary second molar.
Clinical research has recommended direct vision, dental operating microscope (DOM), and selective dentin removal associated with ultrasonics and the use of cone beam computed tomography (CBCT) to help in the identification of MB2 canals in maxillary first and second molars.,, However, to the best of our knowledge, there are no published studies evaluating the clinical detection of MB2 in maxillary molars by clinical methods and CBCT.
Therefore, the purpose of this study was to evaluate the influence of direct vision (Stage I), DOM (Stage II), selective removal of dentin under DOM (Stage III) and by CBCT (Stage IV) in clinical detection of MB2 root canal in maxillary first and second molars. The null hypothesis tested was that there would be no difference between these four stages on MB2 canal detection.
| Materials and Methods|| |
This study was approved by the Institutional Review Board of Dr. MGR Educational and Research Institute University, Chennai, India (Dr MGRDU/TMDCH/ EC/2016-17/0701018). Study subjects were recruited from the pool of patients referred to the Department of Conservative Dentistry and Endodontics, Thai Moogambigai Dental College and Hospital from February 2016 to March 2018.
Patients with maxillary first and second molars indicated for root canal treatment were included in our study. Using nMaster software, with power of 80% and alpha error 5%, a minimum sample size of 114 was required. To compensate for expected attrition, a total of 122 maxillary first and second molars were included. Then the patients were divided into two groups based on their age, Group I (20–40 years) and Group II (41–70 years). Before commencing treatment, informed consent was obtained from all the included patients.
Initial clinical procedures
The principal investigator (K.M) performed all the clinical procedures under the supervision of P.R and A.R.P. After achieving profound anesthesia (2% Lidocaine with 1:100,000 epinephrine), teeth were isolated with rubber dam. An endodontic access cavity was established with sterile endo access bur (Dentsply Maillefer, Ballaigues, Switzerland). Mesio-buccal 1 (MB1), disto-buccal (DB), and palatal (P) canals were located with DG-16 explorer (Hu-Friedy, Chicago, IL) and negotiated with #10 hand K-files (Mani Inc., Utsunomiya, Japan), followed by coronal enlargement using ProTaper S1 (Dentsply Maillefer Ballaigues, Switzerland). 3% sodium hypochorite (Prime Dental Products Pvt. Ltd., Mumbai, India) was used as irrigant during instrumentation.
Stage I (Direct vision)
Access cavity preparation was refined as needed to rhomboidal shape to enhance the visibility of MB2 canal orifice. Under optimal lighting of dental unit without magnification, clear visualization of pulp chamber was attained. Using an endodontic explorer (DG-16), MB2 canal was located by running the explorer from MB1 canal to palatal canal.
Stage II (DOM)
Teeth in which MB2 canal was not located with direct vision were examined under magnification (×16) using DOM (Sanma Lumin Pro, Sanma Medineers Vision Pvt Ltd., Chennai, India) with an endodontic explorer (DG-16) to locate the MB2 canal [Figure 1]a and [Figure 1]b.
|Figure 1: (a) Second mesiobuccal canal located under DOM at × 10 magnification and (b) at × 16 magnification. (c) Selective dentin removal under DOM resulting in (d) detection of MB2 canal. (MB1- first mesiobuccal canal, MB2-second mesiobuccal canal, DB-disto-buccal canal, P-Palatal canal, P1- first palatal canal, P2-second palatal canal)|
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Stage III (Selective dentin removal under DOM)
If the MB2 canal orifice was not located after Stage II, selective dentin removal was carried out using an ultrasonic instrument (ET18D, ETBD - Satelec Acteon, France) or small round bur (Size ½ - 0.6 mm, Mani Inc., Utsunomiya, Japan) at low speed under DOM with ×10 magnification for the selective dentin removal procedure and ×16 magnification for location of MB2 canal. Dentin removal was done from MB1 canal toward palatal canal to an extent of 3 mm. Depth of the dentin removal was restricted to 2 mm apical to the pulpal floor [Figure 1]c and d].
Teeth in which MB2 canal was not identified by Stage III were further investigated with CBCT with a voxel size of 100–200 μm (PLANMECA Romexis 2.9 Helsinki, Finland-limited field of view 5 × 3 cm) to confirm the presence or absence of MB2 canal. If the MB2 canals were visualized in CBCT images, subsequent clinical negotiation of MB2 canal was done under DOM.
Identification of MB2 canal was determined when it was separately negotiated and having a separate exit from MB1 or when it joins the MB1 within 5 mm of the apex. Once the MB2 canal orifice was located, #8 or #10 hand K-files were used to negotiate up to the working length, following which shaping and cleaning was carried out. Throughout the clinical procedure, copious irrigation was done with 3% sodium hypochlorite and obturation was completed during the subsequent visit using gutta-percha and resin sealer (AH Plus; Dentsply DeTrey, Konstanz, Germany).
Statistical analysis was performed using SPSS software (IBM, Armonk, NY). Chi-square test was done to compare the MB2 canal detection rate between the four stages of evaluation. The P value was set at <0.05 for statistical significance.
| Results|| |
A total of 122 maxillary molars (73 maxillary first molars and 49 maxillary second molars) were evaluated in our study. MB2 canals were clinically (Stages I, II, and III) detected in 90% of maxillary molars: 93% in maxillary first molar and 86% in maxillary second molar.
The clinical detection of MB2 canals in Stage I was 64% (78/122). In Stage II, the number of MB2 canals detected increased by 20% (P < 0.001) from 78 to 103 leading to an MB2 detection rate of 84% (103/122) which was significant. In Stage III, the number of MB2 canals detected further increased by 6% (P < 0.001) from 103 to 110 resulting in an overall MB2 clinical detection rate of 90% (110/122) which was significant. CBCT investigation (Stage IV) revealed the presence of additional 3% MB2 canals, leading to overall prevalence of 93% (114/122) for MB2 canals which was significant (P < 0.001).
In terms of Vertucci's root canal configuration, MB root of maxillary first molars had 69% type II (2-1) and 31% type IV configuration (2-2) and MB root of maxillary second molars had 83% type II and 17% type IV configuration.
Based on age, clinical detection of MB2 canals in Group I (20–40 years) was 93% and in Group II (41–70 years) it was 85% which was not significant (P = 0.156).
Based on gender, MB2 canals were clinically detected in 93% of male patients and 88% in female patients which was not significant (P = 0.757).
| Discussion|| |
Maxillary molars erupt early and have a high caries rate leading to frequent endodontic treatment. In maxillary molars, the MB2 canal can be the most difficult to locate and negotiate clinically. MB2 canals are usually curved and its orifice is often covered by secondary dentin. Hence, it is often difficult to diagnose its presence and achieve a straight line access to the apex.
Wolcott et al. in their clinical investigation revealed that 68% of MB2 canals in maxillary first molars and 44% of MB2 canals in maxillary second molars were missed during the initial endodontic therapy and stated that failure to detect MB2 canals will reduce the long-term prognosis. Recently, Karabucak et al. stated that the incidence of missed MB2 canals in maxillary molars was 41% and concluded that teeth with a missed canal were 4.38 times more likely to undergo failure.
MB2 root canal of maxillary molar has been a subject of extensive research.,,, The methodologies to evaluate MB2 canal vary fromin vivo clinical findings, radiographic findings, and CBCT examinations, to ex vivo methodologies, such as clearing technique and micro-computed tomographic evaluation (MICRO-CT).,,,,, However, our study evaluated clinical techniques and CBCT investigation to detect MB2 canal.
In Stage I, after altering the access cavity preparation to rhomboidal shape, the MB2 canal orifice was located in 64% of the teeth. The advantage of rhomboidal shape access cavity for MB2 canal detection has been previously reported.
Under DOM magnification (Stage II), detection of MB2 canals increased by 20% leading to a clinical detection rate of 84%. After selective dentin removal under DOM (Stage III), location of MB2 canals further increased by 6% resulting in an overall clinical detection rate of 90%.
DOM in endodontics has provided the clinician with significantly enhanced magnification and illumination. Previous research has indicated that it enables the detection and negotiation of very fine canals, especially the MB2 canal.,, In the present study, there was a significant increase in the number of clinically detected MB2 canals while comparing direct vision (Stage I) with DOM (Stage II) (P < 0.001) and Stage II with selective dentin removal under DOM (Stage III) (P < 0.001) which was in agreement with previous research.,,,
In our study, 12 teeth (Group I: 5, Group II: 7) which did not have clinically identifiable MB2 canal at the conclusion of Stage III where further investigated with CBCT (Stage IV) to confirm the presence or absence of MB2 canal. After viewing the CBCT images, 4 of the 12 (Group I: 3, Group II: 1) teeth were found to have MB2 canals which were subsequently negotiated clinically under DOM. CBCT investigation further improved the identification of MB2 canal leading to overall prevalence of 93% which was significant (P < 0.001). Because there was a significant difference in detection of MB2 canals among the four stages evaluated our null hypothesis was rejected.
CBCT imaging has been widely used in endodontics for various applications and it is considered to be the gold standard diagnostic tool forin vivo studies. CBCT investigation allows the clinician to assess root morphology in three dimensions. It can be used to confirm the presence of an MB2 canal in maxillary molars. The prevalence of MB2 canal with CBCT examination ranges from 63% to 85.,
However, subjecting every patient to CBCT investigation may not be appropriate, as outlined in the joint position statement of American Association of Endodontists and the American Academy of Oral and Maxillofacial Radiology (AAE/AAOMR) on the use of CBCT in endodontics. Whenever MB2 canals were not identified clinically, a CBCT scan with limited field of view could increase the potential of locating an MB2 canal.
Fogel et al. and al Shalabi et al. stated that older patients (above 45 years) had only one treatable canal in MB root of maxillary molar. However, Gilles and Reader have stated that MB2 canals and orifices may become smaller with age but complete occlusion of the MB2 canal was unlikely. Similarly, in our study, the clinical detection of MB2 canals does not vary significantly (P = 0.156) between the two age groups. However, CBCT did not reveal MB2 canal in 2 teeth from Group I (20–40 years) and 6 teeth from Group II (41–70 years).
Also, in our study, there was no significant influence (P = 0.757) of gender (Males-93% and Females-88%) on clinical detection of MB2 canal, which was in accordance with previous studies., One of the limitations of the present study was that CBCT scans were not made for all patients to evaluate root canal anatomy. However, this was not done to reduce the radiation exposure and CBCT scans were done only for patients for whom MB2 canals were not clinically detected.
| Conclusion|| |
The results of our study indicate that MB2 canal can be clinically detected in up to 90% of maxillary molars utilizing DOM combined with selective dentin removal. CBCT investigation is indicated when MB2 canals are not clinically detected.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient (s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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Prof. Angambakkam Rajasekaran Pradeep Kumar
Department of Conservative Dentistry and Endodontics, Thai Moogambigai Dental College & Hospital, Dr. MGR Educational and Research Institute (Deemed to be University), Chennai - 600 095, Tamil Nadu
Source of Support: None, Conflict of Interest: None
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