What Are The Risk Factors For External Root Resorption of Second Molars Associated With Impacted Third Molars?

Publication date: Available online 4 September 2018

Source: Journal of Oral and Maxillofacial Surgery

Author(s): Melek Tassoker

Purpose

In relation to an impacted third molar, which is the most frequently impacted tooth, external root resorption (ERR) or dental caries can be seen on the distal surface of the adjacent second molar. The purpose of this study was to investigate the risk factors of ERR in second molars associated with impacted third molars using cone-beam computed tomography (CBCT).

Materials and Methods

In this cross-sectional study, the presence of ERR on the adjacent second molar was investigated retrospectively on sagittal and axial CBCT slices of the patients, who underwent CBCT examination for diagnostic reasons (surgical removal of third molars, orthodontic assessments, etc.) between 2013 and 2017, at Necmettin Erbakan University, Faculty of Dentistry, Konya, Turkey. The primary outcome variable was ERR (y/n). Predictor variables included demographic (age and gender) and radiographic (impacted tooth angulation and tooth type) parameters. Given there are multiple observations per subject (1 to 4 impacted teeth), one third molar was selected per subject at random for study inclusion. Statistical analysis was performed using the descriptive statistics, Mann-Whitney U test, and Pearson's chi-squared test. Logistic regression analysis was used to determine the risk factors for ERR in second molars. Cohen's Kappa test was used for testing the intra-observer agreement. The significance level was set at p < 0.05.

Results

Two hundred patients were analyzed and of the 200 impacted third molars evaluated 42 (21%) showed ERR. It was found that the severity of resorption increased with aging (p<0.05). Logistic regression analysis indicated that tooth number and inclination of third molars could predict the occurrence of ERR associated with an impacted third molar (p<0.05).

Conclusion

Mesioangular and horizontal inclinations and impacted mandibular third molars posed a greater risk for ERR lesions in adjacent second molars than other inclinations (distoangular and vertical) and maxillary third molars.

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