Radiographic features of anatomic relationship between impacted third molar and inferior alveolar canal on coronal CBCT images: risk factors for nerve injury after tooth extraction.

INTRODUCTION: The present study was aimed to identify the radiographic signs between impacted third molar root and inferior alveolar canal (IAC) on cone-beam CT (CBCT) images as risk factors and prognostic predictors associated with inferior alveolar nerve (IAN) damage following tooth removal. MATERIAL AND METHODS: A retrospective clinical study was performed involving 136 patients with 257 impacted lower third molars from January 2013 to December 2014. The neurosensory function of the lower lip and chin was subjectively evaluated and assessed by neurosensory tests before and after surgery. The preoperative CBCT data were retrieved and analyzed to identify the radiographic signs associated with postoperative IAN injury. RESULTS: The overall incidence of IAN injury in our patient cohort was 13.2%. Multiple radiographic features on coronal CBCT images including contact between IAC and root, IAC position relative to root, IAC shape and cortication status were found to be significantly associated with IAN damage (p < 0.05, χ2 test). Furthermore, buccolingual position, teardrop/dumbbell shape and cortication status of IAC were identified as independent prognostic predictors for IAN damage. CONCLUSIONS: Our findings indicate that radiographic signs including direct contact between IAC and root, buccal/lingual IAC position relative to root, teardrop/dumbbell shape and cortication absence of the IAC on presurgical CBCT images are associated with high risk of IAN injury and postoperative neurosensory disturbance.

Overexpression of suppressor of zest 12 is associated with cervical node metastasis and unfavorable prognosis in tongue squamous cell carcinoma.

OBJECTIVE: Increased expression of suppressor of zest 12 (SUZ12), a core component of the polycomb repressive complex 2, contributes to human tumorigenesis and associates with patient prognosis. In the present study, we sought to investigate the expression of SUZ12 and its clinicopathological significance in primary tongue squamous cell carcinoma (TSCC). METHODS: The expression of SUZ12 protein was determined by immunohistochemistry in clinical samples from a retrospective cohort of 72 patients with primary TSCC who were treated at our institution from Jan. 2007 to Dec. 2013. The potential associations between SUZ12 abundance and multiple clinicopathological parameters were assessed by Chi square test. Moreover, the effect of SUZ12 expression on patients' survival was further estimated by Kaplan-Meier and Cox regression analyses. RESULTS: Our immunohistochemical staining data revealed aberrant overexpression of SUZ12 in a large subset of TSCC as compared to normal tongue mucosa. Elevated SUZ12 was found to be significantly associated with cervical nodes metastasis (P = 0.0325) and reduced overall as well as disease-free survival (Log-rank test, P = 0.0225, 0.0179, respectively). Both univariate and multivariate Cox regression analysis identified the expression status of SUZ12 (low/high) as an important independent prognostic factor for patients' survival. CONCLUSIONS: Our data reveal that aberrant SUZ12 overexpression is associated with cervical nodes metastasis and reduced survival in TSCC. These findings suggest that SUZ12 might play critical roles during tongue tumorigenesis and serve as a novel biomarker with diagnostic and prognostic significance.