Reliability of panoramic radiography in predicting proximity of third molars to the mandibular canal: A comparison using cone-beam computed tomography

Association of indications for mandibular third molar coronectomy and the Pell and Gregory and the Winter classification systems

PURPOSE

The purpose of this study was to determine how the surgeon's decision to perform a mandibular third molar coronectomy or surgical removal is associated with the impaction pattern as classified using Pell and Gregory or Winter's system.

METHODS

This observational, cross-sectional study was conducted on 813 mandibular third molars belonging to 565 patients. All patients were referred for removal of the mandibular third molar and had radiographic signs indicating a close relationship with the inferior alveolar nerve. Panoramic images were classified according to the impaction pattern.

RESULTS

A coronectomy was performed on 492 (60.5%) mandibular third molars. Most impacted mandibular third molars were class IIB with a mesioangular inclination. A significant association was found between the Pell and Gregory classification and the surgeon's choice (p = 0.002). Winter's classification was not significantly associated with surgeon choice (p = 0.425).

CONCLUSION

Mandibular third molar coronectomy is chosen more frequently than surgical removal if molars are class III and position B.

TRIAL REGISTRATION NUMBER

Not applicable.

Investigation of the relationship between the mandibular third molar teeth and the inferior alveolar nerve using posteroanterior radiographs: a pilot study

BACKGROUND

The most severe complication that can occur after mandibular third molar (MM3) surgery is inferior alveolar nerve (IAN) damage. It is crucial to have a comprehensive radiographic evaluation to reduce the possibility of nerve damage. The objective of this study is to assess the diagnostic accuracy of panoramic radiographs (PR) and posteroanterior (PA) radiographs in identifying the association between impacted MM3 roots and IAN.

METHODS

This study included individuals who had PR, PA radiographs, and cone beam computed tomography (CBCT) and who had at least one impacted MM3. A total of 141 impacted MM3s were evaluated on CBCT images, and the findings were considered gold standard. The relationship between impacted MM3 roots and IAN was also evaluated on PR and PA radiographies. The data was analyzed using the McNemar and Chi-squared tests. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and diagnostic accuracy of PR and PA radiographies were determined.

RESULTS

Considering CBCT the gold standard, the relationship between MM3 roots and IAN was found to be statistically significant between PR and CBCT (p = 0.00). However, there was no statistically significant relationship between PA radiography and CBCT (0.227). The study revealed that the most prevalent limitation of the PR in assessing the relationship between MM3 roots and IAN was the identification of false-positive relationship.

CONCLUSIONS

PA radiography may be a good alternative in developing countries to find out if there is a contact between MM3 roots and IAN because it is easier to get to, cheaper, and uses less radiation.

Risk factors for external root resorption of maxillary second molars associated with third molars

Purpose

This study aimed to evaluate the diagnostic performance of panoramic images compared to cone-beam computed tomography (CBCT) imaging for maxillary third molar (M3)-associated external root resorption (ERR), and to identify the risk factors of ERR on panoramic images.

Materials and Methods

The study population was composed of all patients who underwent panoramic imaging at Dankook University Dental Hospital from May to October 2019. In total, 397 cases of maxillary M3s in 247 patients (147 men and 100 women) were included. The diagnostic accuracy of ERR in panoramic images compared to CBCT images was evaluated using the chi-square test. To identify risk factors for ERR, dental records and panoramic findings were evaluated by logistic regression analysis.

Results

The diagnostic accuracy of ERR on panoramic images was 0.79 compared to CBCT images (P<0.05). Superimposition of M3s onto second molars (M2) was associated with an approximately 33 times higher risk of ERR than separated M3s (P<0.05). Impacted M3s showed a 5 times higher risk of ERR than erupted M3s (P<0.05).

Conclusion

ERR related to M3s is a common clinical condition, and superimposition of M3 onto M2 on panoramic images was the most important risk factor for ERR. It seemed that CBCT examinations for maxillary M3s might be indicated for ERR diagnosis especially if panoramic radiographs show superimposition of M3 onto M2. Impaction itself was also a risk factor, and it should be carefully examined.