Objective: To compare the diagnostic performance between panoramic radiography(PR)and cone beam computed tomography(CBCT)in the assessment of external root resorption(ERR)of mandibular second molars associated with impacted third molars. Methods: A total number of 832 patients with 1 074 mesially and horizontally impacted mandibular third molars treated at our institution from January 2019 to December 2020 were retrospectively analyzed. Presence of ERR on the adjacent second molar was investigated with PR and CBCT. Factors affecting the diagnostic accuracy of PR were determined. Results: The overall incidence of ERR in second molars was 33.15%(356/1 074)as detected by CBCT images. The accuracy of PR was 66.39%. Multivariate Logistic regression analyses further revealed that middle and Class Ⅲ impaction, crown contact or overlap with the root of adjacent tooth were risk factors for inaccurate diagnosis of PR(P<0.05). Conclusion The accuracy of detection on ERR of mandibular second molar associated with impacted third molar using panoramic radiography is lower. CBCT is recommended for this clinical scenario.

ObjectiveTo explore whether fluoroethylnormemantine （FENM）， an NMDA receptor antagonist， could improve compulsive-like behaviors and to investigate its underlying mechanisms in the RU24969-induced obsessive-compulsive disorder （OCD） mouse model. MethodsThirty-two mice were randomly assigned to four groups： Saline （n=8）， RU24969 （n=8）， RU+FENM （n=8）， and FENM （n=8）. Mice received FENM or an equivalent volume of saline for pre-treatment， followed by RU24969 or saline for model induction 30 minutes later. Behavioral tests were performed 1 hour after modeling， and serum samples were collected to measure the level of brain-derived neurotrophic factor （BDNF）. Evans Blue dye was intravenously injected to assess dye content in brain tissue， thereby evaluating potential blood-brain barrier damage. ResultsFENM treatment significantly improved repetitive stereotyped circling behavior （F=39.850， P＜0.001） and alleviated persistent motor activity （F=50.200， P＜0.001） in RU24969 model mice. Additionally， FENM treatment significantly increased serum BDNF level in RU24969-induced OCD mice （F=18.930， P＜0.001）. ConclusionsFENM ， an NMDA receptor antagonist， may alleviate compulsive behaviors in OCD mice by modulating BDNF levels ， thereby exerting anti-compulsive effects. Neither the RU24969 model nor FENM treatment significantly affectes blood-brain barrier integrity.