"Retrospective Study of the Risk of Pathology in the Mandibular Second Molar Associated With an Impacted Third Molar: Development and Validation of a Semi-Automated Artificial Intelligence-Based Digitisation Platform". (SMART-M3)
Impacted mandibular third molars (wisdom teeth that cannot fully erupt) may damage the adjacent second molar, causing decay on its back surface, loss of the supporting bone or resorption of its root. These problems are often silent and are detected late. This retrospective observational study aims to identify which radiographic features of the impacted third molar are associated with a higher risk of pathology in the second molar.
The study uses panoramic radiographs (OPG) and cone-beam computed tomography (CBCT) scans that were previously obtained for clinical reasons at the UCAM Dental University Clinic (Murcia, Spain) between 2018 and 2026. No new images or procedures are performed on patients. The position, angulation, depth and contact of the third molar with the second molar are measured, and their relationship with second molar pathology is analysed. The study also compares the information provided by OPG and CBCT and develops and validates a semi-automated, artificial intelligence-based platform to help clinicians make these radiographic measurements faster and more consistently.
Study Overview
Status
Intervention / Treatment
Detailed Description
Design. Single-centre, observational, cross-sectional, retrospective study approved by the Ethics Committee of the Universidad Católica San Antonio de Murcia (code CE102517). It follows the Declaration of Helsinki. Informed consent was waived because only pre-existing images obtained for clinical purposes are used. Data are pseudonymised in accordance with Regulation (EU) 2016/679 (GDPR) and Spanish Organic Law 3/2018.
Setting and sample. Consecutive sampling of all eligible images acquired at the UCAM Dental University Clinic between February 2018 and June 2026 with an ORTHOPHOS SL 3D unit (Dentsply Sirona). The unit of analysis is the mandibular third molar, so each patient may contribute one to four records (one or two third molars, on OPG, CBCT or both). The expected sample is approximately 2,110 third molars from 1,188 patients on OPG and approximately 690 third molars from 384 patients on CBCT, with a paired OPG-CBCT subsample of 667 teeth.
Variables. Third molar variables are:
- Winter classification
- Pell & Gregory depth and ramus relationship
- Retromolar space
- Angle between the long axes of the second and third molars
- Distance from the distal surface of the second molar to the ramus
- Mesiodistal diameter of the third molar
- Presence, type and level of contact between the third and second molars Covariates are age, sex and smoking status. Outcome. The primary outcome is a composite of distal pathology of the mandibular second molar, defined as the presence of at least one of the following: distal caries, distal bone loss or external root resorption. Teeth without any of the three are classified as controls. Each component is also recorded separately, with its extent or severity.
Statistical analysis. The analysis comprises:
- Descriptive statistics, overall and by imaging modality.
- Bivariate analysis using chi-square or Fisher's exact tests and Mann-Whitney U or Student's t tests, with odds ratios, 95% confidence intervals and correction for multiple comparisons.
- Multivariable mixed-effects logistic regression with the patient as a random effect, to account for the clustering of teeth within patients.
- Assessment of the model's discrimination with ROC curves and AUC.
- Agreement between OPG and CBCT in the paired subsample, using intraclass correlation coefficients, simple and weighted kappa and Bland-Altman analysis, with 95% confidence intervals obtained by patient-clustered bootstrap.
- Intra-observer reliability on 123 teeth per modality. AI-based platform. A semi-automated digitisation platform based on artificial intelligence (automatic landmark detection) is developed to perform the radiographic measurements. It is validated against expert manual assessment in an independent subsample of 191 third molars (103 OPG and 88 CBCT).
Study Type
Enrollment (Actual)
Contacts and Locations
Study Locations
-
-
Murcia
-
Murcia, Murcia, Spain, 30008
- Clínica Universitaria UCAM Dental
-
-
Participation Criteria
Eligibility Criteria
Ages Eligible for Study
Accepts Healthy Volunteers
Genders Eligible for Study
Sampling Method
Study Population
Adult patients (18 years or older) who attended the UCAM Dental University Clinic (Murcia, Spain) between February 2018 and June 2026 and had at least one mandibular third molar visible on a panoramic radiograph (OPG) and/or cone-beam computed tomography (CBCT) scan obtained previously for clinical purposes. Patients were identified consecutively through the clinic's records management software (GESDEN).
Description
Inclusion Criteria:
- Age 18 years or older.
- Age and sex recorded.
- At least one mandibular third molar present.
- OPG and/or CBCT available.
Exclusion Criteria:
- Absence of the adjacent second mandibular molar.
- Insufficient diagnositc image quality.
- Previous surgery altering the anatomy.
- Cysts or tumours in the third molar region.
Study Plan
How is the study designed?
Design Details
- Observational Models: COHORT
- Time Perspectives: RETROSPECTIVE
Cohorts and Interventions
Group / Cohort |
Intervention / Treatment |
|---|---|
|
OPG cohort
Patients with an impacted mandibular third molar assessed on panoramic radiography. |
The radiographic assessment was performed on images that were already available. No additional exposure was required. |
|
CBCT cohort
Subset of patients also assessed on CBCT. |
The radiographic assessment was performed on images that were already available. No additional exposure was required. |
What is the study measuring?
Primary Outcome Measures
Outcome Measure |
Measure Description |
Time Frame |
|---|---|---|
|
Primary
Time Frame: At the time of the radiographic examination (single cross-sectional assessment).
|
Composite distal pathology of the mandibular second molar (distal caries, distal bone loss and/or external root resorption). |
At the time of the radiographic examination (single cross-sectional assessment).
|
Secondary Outcome Measures
Outcome Measure |
Measure Description |
Time Frame |
|---|---|---|
|
Secondary
Time Frame: At the time of the radiographic examination (single cross-sectional assessment).
|
Agreement between OPG and CBCT measurements (ICC, weighted kappa, Bland-Altman). |
At the time of the radiographic examination (single cross-sectional assessment).
|
Collaborators and Investigators
Study record dates
Study Major Dates
Study Start (Actual)
Primary Completion (Actual)
Study Completion (Estimated)
Study Registration Dates
First Submitted
First Submitted That Met QC Criteria
First Posted (Actual)
Study Record Updates
Last Update Posted (Actual)
Last Update Submitted That Met QC Criteria
Last Verified
More Information
Terms related to this study
Additional Relevant MeSH Terms
Other Study ID Numbers
- CE102517
Plan for Individual participant data (IPD)
Plan to Share Individual Participant Data (IPD)?
IPD Plan Description
Pseudonymised clinical images subject to GDPR; data available from the corresponding author upon reasonable request.
Drug and device information, study documents
Studies a U.S. FDA-regulated drug product
Studies a U.S. FDA-regulated device product
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