Keywords
OPG, CBCT, impacted, third molar
This article is included in the Datta Meghe Institute of Higher Education and Research collection.
OPG, CBCT, impacted, third molar
Impaction is the failure of eruption of a tooth in human dentition within an estimated time period (e.g.,: mandibular third molar is expected to erupt in oral cavity by 21 yrs of age) due to insufficient space, malposition of tooth or physical barriers on the eruption path of the tooth.1 The mandibular third molar is commonly the most impacted tooth in the entire permanent dentition of an oral cavity.2 The cause of this impaction can vary. It could be due to a shortage of space for eruption or failure of the tooth to rotate to the mesioangular and vertical position from its horizontal position.1,2 Also, the various changes that occur with the position of the mandibular third molar could be due to alteration in its usage and demands for function such as its reduced function in mastication and change in the total arch length of human dentition.1
The impaction of mandibular third molar can cause a number of pathological conditions such as pericoronitis, bone loss, resorption of an adjacent root, periodontal diseases, odontogenic infections, odontogenic cysts and tumours and even jaw fractures.2,3 It can also have adverse effect on the adjacent second molar causing distal caries and root resorption.4
The mandibular third molar is very much capable of causing pain, irritation and has the capacity to cause pathological conditions in its surrounding areas as mentioned above. Due to its decrease in function with mastication, it is commonly removed by surgical extraction1,5,6
Orthopantomography (OPG) is a two-dimensional radiography technique, mainly used to see the mandibular third molar impaction status and its relation to the surrounding structures and estimate the complications that can arise due to injury of the inferior alveolar nerve.7–10 A study done by Patel PS et al9 on 200 mandibular third molar impacted teeth. In that study they showed that the sensitivity and specificity of OPG in assessing mandibular third molar relation to inferior alveolar canal is 98.55% and 48.39% respectively
Due to its three-dimensional imaging ability, cone beam computed tomography (CBCT) seems to be particularly beneficial, especially for third molars in the mandible that may be closely related to the mandibular alveolar nerve canal since it can provide a spatial resolution of the relationship between these two structures.9,11
This will be a diagnostic study. This is a hospital-based study where the participants will receive consent in written form. They will be recruited from Oral Medicine and Radiology department of Sharad Pawar Dental college and Hospital, Sawangi (Meghe), Wardha. Approval has been received a from “INSTITUTIONAL ETHICS COMMITTEE (IEC)” of Datta Meghe Institute of Medical Science (Deemed to be University), Sawangi (Meghe), Wardha (Approval number DMIMS (DU)/IEC/2022/764 Dated 14/02/2022). This prospective study will be conducted in Oral Medicine and Radiology Department at Sharad Pawar Dental College and Hospital, Sawangi (Meghe), Wardha. Patients with third molar impaction who reported to the department of Oral Medicine and Radiology will be taken for radiography using OPG and after seven days a radiograph will be taken again using CBCT of the same patient. This is to ensure patient’s safety against overexposure to radiation.
All patients above 21 years of age with a unilateral or bilateral mandibular third molar impacted tooth that present to the hospital will be recruited. Consent will be taken from each patient for inclusion in this study.
Patients who presented with congenital or developmental abnormalities of jaw, with bony lesion of jaw (cyst, odontogenic tumor or fibro-osseous lesion), with adjacent impacted or missing 2nd molar or if they have a history of trauma of jaw (confirmed clinically and radiographically) will be excluded.
After identifying patients who are 21 years of age and above who’s mandibular third molar on clinical examination are impacted or has not erupted yet in the oral cavity and from whom consent has been taken, the procedure will begin. Each patient will be taken for OPG (Planmeca proline cc) where radiographic film will be printed and will be kept for evaluation. After 7 days, the same patient will be recalled and this time, they will be taken for CBCT (Planmeca Promax). After exposing the patient to CBCT, an image will be obtained from Romexis viewer software and image will be printed. Comparison of OPG imaging with CBCT will be done under two parameters.
The first parameter which will be included is the proximity of root apex of IMTM to Mandibular canal in OPG and compare the findings with CBCT where CBCT will be used as gold standard (as CBCT is considered to be accurate enough as it provides 3D imaging). If root apex of IMTM appears to contact or not contact Mandibular canal in OPG image, this will be compared with CBCT image to see if it gives the same result or different interpretation. This will provide the sensitivity and specificity of OPG for this particular finding as given in Table 1. The second parameter to be included is status of root resorption of the adjacent 2nd molar (as IMTM can cause root resorption of the adjacent tooth4) using Nemcovsky criteria4 (Table 2). On assessing OPG, if a defect is seen on the root of adjacent 2nd molar that satisfy any of the grading of Nemcovsky criteria, it will be compared in CBCT imaging (gold standard) and will evaluate whether OPG gives positive result or not as given in Table 3.
True positive | True negative | False positive | False negative | Sensitivity % | Specificity % | |
---|---|---|---|---|---|---|
Contact or Not contact |
True positive | True negative | False positive | False negative | Sensitivity % | Specificity % | |
---|---|---|---|---|---|---|
Root resorption present or absent |
All assessment and interpretations will be done by 1 Post graduate student and will be re-evaluated by 2 professors. If different opinion in interpretation occurs amongst them, further evaluation will be done until all evaluators unanimously agreed with one interpretation. All findings will be recorded in excel sheet and will be send for statistical evaluation.
This study will begin recruiting patients in 1st September of 2023 and will begin taking patients for OPG and CBCT and at the same time interpretation for the two parameters mentioned in the methodology will be done. This process will be done till 31st of December 2023. In the month of January 2024 statistical analysis along with result evaluation will be done.
Minimum sample size required on the basis of sensitivity estimation
Where n = sample size, Z = 95% Confidence interval, d = desired error of margin, Sens = Sensitivity, Prev = Prevalence
Estimated Sensitivity of OPG the diagnostic accuracy of panoramic radiograph (while keeping CBCT findings as gold standard) in predicting close relation between the impacted third molar root and inferior alveolar nerve canal = 0.9855. (from the reference article9).
Prevalence of relation between the impacted third molar root and inferior alveolar nerve canal to correctly identify the state of impaction, with mandibular canal considering the estimated probability value of 50% = 0.5.
Estimation Error (d) 5% = 0.05
Z (1-α/2) = 1.96 at 5% Error
n = 44
Total sample size required is 44
SPSS, 207.0 version of software will be used for statistical analysis (PSPP is a proprietary free alternative that can be utilized). Chi square test will be used to find the association with demographic variables. Sensitivity, specificity, positive predictive values (PPV) and negative predictive values (NPV) will be calculated for OPG using CBCT as gold standard and evaluation will be based on confirmation of whether apex of IMTM has contact Mandibular canal and whether root resorption is present on adjacent 2nd molar. The percentage of agreement (positive agreement, negative agreement, overall agreement) will be evaluated based on agreement analysis (on primary and secondary endpoints) in comparison between the two procedures. The Kappa coefficient will be used to find out the value of agreement statistics tested with a significant p-value < 0.05 and at 95% confidence interval.
Dissemination: This study is expected to start from September 2023. Once completed manuscript with details of result and statistical analysis will be published in Indexed journal.
Evaluating the status of mandibular third molar with its surrounding dento-alveolar structures is highly applicable in the approach for its management and to avoid any serious complications that can occur post operatively and prevent any detrimental effect it can have on its adjacent second molar (especially with distal caries). OPG is a very useful and easily accessible radiograph. As it provides a two dimensional imaging, proximity of apex of IMTM to mandibular canal can be assessed and if the accuracy is close to that of CBCT which gives 3 dimensional imaging, OPG alone will be sufficient enough to alert the surgeons whether apex of root of IMTM is contacting Mandibular canal or not and help prevent any major post-surgical complication.
A study was conducted by Zahra Haddad et al2 on the position of impacted mandibular third molar and their relationship with pathological conditions on panoramic radiograph. 1600 samples of mandibular impacted third molar were evaluated out of which 195(12.2%) had caused distal caries of second molar, 252(15.8%) has caused resorption of the second molar root, 119(7.4%) had caused pathological lesion, 872(54.5%) had contact with mandibular canal. They concluded that frequency of complications related with mandibular impacted third molar was low but considerable.
Priya Prabhakar et al1 also conducted a study on the prevalence of pathological conditions with mandibular third molar. A sample size of 200 students were taken between 21 to 25 years. On clinical examination 23% presented pericoronitis, 12% had periodontal pocket, 8% had proximal caries with no tooth or bone resorption. It is concluded that there is significantly lesser impact of third molar to adjacent second molar and further studies are required with larger sample size.
P Vani Priya et al7 also performed a study on assessment of impacted mandibular third molar using OPG and intra oral periapical radiograph. 200 patients suffering from pericoronitis were evaluated and among them 50 patients were selected for further studies as the rest of the patients had problem or are not willing to participate for the study. The types of impactions, the space availability, root curvature, relation to the adjacent second molar, the number of roots of impacted third molar and juxtaposition to the nerve were observed. This study showed that IOPA was more useful in determining relation of the third molar with oblique ridge (IOPA vs OPG = (96%:90%), anterior to posterior relation with the ramus (IOPA vs OPG = 70%:66%), depth of impaction vertically (IOPA vs OPG = 72%:68%), number of roots and root morphology. However, OPG is more precise in determining the type of impaction and its relation to the canal.
Aya Ohshima et al3 conducted a study on the structure of impacted mandibular third molar with its relation to the surrounding structures using CBCT. This study used 87 patients who are uninfected and 12 patients who were infected. Result showed that 48 (35.3%) had disappearance of the lingual cortical plate and 11 (8.1%) had disappearance of buccal cortical plate. It was concluded that CBCT acts as an effective tool to assess the pathway of infections that originates from impacted mandibular third molar.
Zenodo: Comparative evaluation for the accuracy of mandibular third molar impaction status with respect to surrounding dentoalveolar structures using orthopantomogram (OPG) as against cone beam computed tomography (CBCT), https://doi.org/10.5281/zenodo.8167904. 12
This project contains the following extended data:
Data are available under the terms of the Creative Commons Attribution 4.0 International license (CC-BY 4.0).
I want to sincerely thank Dr Manoj Patil sir and Laxmikant Umate Sir for helping me with the framework of this protocol.
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Is the rationale for, and objectives of, the study clearly described?
Yes
Is the study design appropriate for the research question?
No
Are sufficient details of the methods provided to allow replication by others?
Partly
Are the datasets clearly presented in a useable and accessible format?
Not applicable
Competing Interests: No competing interests were disclosed.
Reviewer Expertise: Oral cancer, Oral Precancer, Facial Trauma, Oral Epithelial Dysplasia, Dental Education, Medically compromised patients
Is the rationale for, and objectives of, the study clearly described?
Yes
Is the study design appropriate for the research question?
Yes
Are sufficient details of the methods provided to allow replication by others?
Partly
Are the datasets clearly presented in a useable and accessible format?
No
Competing Interests: No competing interests were disclosed.
Reviewer Expertise: Cephalometry and dental radiography, Cleft lip and palate, malocclusion assessment, orthognathics surgery,
Alongside their report, reviewers assign a status to the article:
Invited Reviewers | ||
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Version 1 01 Dec 23 |
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