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Study Protocol

Comparative evaluation for the accuracy of mandibular third molar impaction status with respect to surrounding dentoalveolar structures using orthopantomogram as against cone beam computed tomography

[version 1; peer review: 2 not approved]
PUBLISHED 01 Dec 2023
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This article is included in the Datta Meghe Institute of Higher Education and Research collection.

Abstract

Mandibular third molar impaction impose a great dental problem especially to young adults. It is the most commonly impacted tooth in the entire dentition of humans. The cause of impaction may vary and may include lack of space, malposition and physical barrier on the path of eruption. This impaction can lead to different pathologies, from infection to development of cysts. Injury to the inferior alveolar nerve during extraction of mandibular third molar is also a possibility during treatment which can lead to numbness, tingling or burning sensation of the affected side. It can also have adverse effects on the adjacent second molar. Several studies have been done to determine the angulation, depth of impaction, space available between the second molar and ramus, proximity to inferior mandibular third, status of adjacent second molar using several criteria and classification using orthopantomography (OPG) and cone beam computed tomography (CBCT). But there is very little research done on the precision of both OPG and CBCT and comparisons of their diagnostic accuracy. In this study, adults above 21 years of age who have impacted mandibular third molar (IMTM) will be taken for OPG where OPG will provide two-dimensional radiography and CBCT will deliver three-dimensional radiography. Different criteria will be used to assess the status of the impaction and see the sensitivity and specificity in both OPG and CBCT. This study is important to help determine which radiographic diagnostic tool is preferable for assessing the status of impacted third molar and its relation to its surrounding structures and estimate the difficulty index for extraction of mandibular third molar impaction. It will also further help in preventing any injury or complication which can arise to the surrounding structures both during and after extraction and which will also help in achieving best possible outcome for patients.

Keywords

OPG, CBCT, impacted, third molar

Introduction

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.710 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

Objectives

  • - To assess accuracy of proximity of root apex of IMTM in OPG and compare it with CBCT

  • - To evaluate the accuracy of status of root resorption of adjacent 2nd molar in OPG against CBCT

Protocol methods

Study design

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.

Inclusion criteria

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.

Exclusion criteria

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.

Experimental methods

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.

Table 1. Proximity of root apex of IMTM to Mandibular canal in OPG.

True positiveTrue negativeFalse positiveFalse negativeSensitivity %Specificity %
Contact or Not contact

Table 2. Nemcovsky criteria of external root resorption.4

Grade ANo evidence of any root resorption
Grade BIrregular defect noted on root surface and exceeding 2 mm depth
Grade CObvious irregularities noted exceeding 2 mm with involvement of the root is maintained
Grade DResorption involving the pulp with loss of root shape
Grade ETotal root resorption

Table 3. Root resorption status of adjacent 2nd molar in OPG (Nemcovsky criteria of external root resorption.4

True positiveTrue negativeFalse positiveFalse negativeSensitivity %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.

Duration of study

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.

Sample size calculation

Minimum sample size required on the basis of sensitivity estimation

n=Z1α/22Sens1Sensd2XPrev
n=1.96^20.985510.9855/0.05^20.5=44.

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

Statistical analysis plan

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.

Study status

Preliminary preparations are in process. Patients have been recruited and will shortly be taken for radiograph using OPG and after 7 days CBCT.

Discussion

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.

Ethical considerations

Approval was obtained from Institutional Ethics committee of Datta Meghe Institute of Medical Science. No. DMIMS (DU)/IEC/2022/764. Written informed consent will be taken from all patients that meet our criteria for recruitment.

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Lalremtluangi R and Khasbage SD. Comparative evaluation for the accuracy of mandibular third molar impaction status with respect to surrounding dentoalveolar structures using orthopantomogram as against cone beam computed tomography [version 1; peer review: 2 not approved]. F1000Research 2023, 12:1545 (https://doi.org/10.12688/f1000research.135179.1)
NOTE: If applicable, it is important to ensure the information in square brackets after the title is included in all citations of this article.
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Key to Reviewer Statuses VIEW
ApprovedThe paper is scientifically sound in its current form and only minor, if any, improvements are suggested
Approved with reservations A number of small changes, sometimes more significant revisions are required to address specific details and improve the papers academic merit.
Not approvedFundamental flaws in the paper seriously undermine the findings and conclusions
Version 1
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Reviewer Report 22 May 2024
Mohamed Jaber, Ajman University, Ajman, United Arab Emirates 
Not Approved
VIEWS 1
1. Title: Comparative Evaluation of Orthopantomography and Cone Beam Computed Tomography in Assessing Mandibular Third Molar Impaction
  • The title adequately conveys the main focus of the study, which is to compare the accuracy of assessing mandibular
... Continue reading
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CITE
HOW TO CITE THIS REPORT
Jaber M. Reviewer Report For: Comparative evaluation for the accuracy of mandibular third molar impaction status with respect to surrounding dentoalveolar structures using orthopantomogram as against cone beam computed tomography [version 1; peer review: 2 not approved]. F1000Research 2023, 12:1545 (https://doi.org/10.5256/f1000research.148282.r259646)
NOTE: it is important to ensure the information in square brackets after the title is included in all citations of this article.
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Reviewer Report 13 Mar 2024
Phumzile Hlongwa, University of Pretoria, Pretoria, South Africa 
Not Approved
VIEWS 7
The Research protocol need further revisions.
It is suggested that the sample size calculation section follows:
  • This will be a diagnostic study. – replace “diagnostic ‘ with “observational”
  • “This prospective study will be
... Continue reading
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CITE
HOW TO CITE THIS REPORT
Hlongwa P. Reviewer Report For: Comparative evaluation for the accuracy of mandibular third molar impaction status with respect to surrounding dentoalveolar structures using orthopantomogram as against cone beam computed tomography [version 1; peer review: 2 not approved]. F1000Research 2023, 12:1545 (https://doi.org/10.5256/f1000research.148282.r251442)
NOTE: it is important to ensure the information in square brackets after the title is included in all citations of this article.

Comments on this article Comments (0)

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VERSION 1 PUBLISHED 01 Dec 2023
Comment
Alongside their report, reviewers assign a status to the article:
Approved - the paper is scientifically sound in its current form and only minor, if any, improvements are suggested
Approved with reservations - A number of small changes, sometimes more significant revisions are required to address specific details and improve the papers academic merit.
Not approved - fundamental flaws in the paper seriously undermine the findings and conclusions
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