Objective To evaluate the accuracy and reliability of cone-beam computed tomography (CBCT) in the diagnosis of periodontal bone defects in the elderly.Methods The 38 teeth of 27 cases were collected and scanned both with CBCT technology and periapical radiography (PA).Periodontal bony defects were identified and linear measurements were made for all defects.All cases were treated with periodontal flap surgery with the bony defects and their linear measurements detected during operation as the gold standard.Results All periodontal bony defects were identified with CBCT with its accuracy rate of 100.0％ (72/72),but the buccal and lingual defects could not be measured by PA with its accuracy rate of 62.5％ (45/72).Linear measurements for all defects revealed no statistical differences between CBCT and direct measurement [(5.516 ± 0.393) mm vs.(5.385± 0.415) mm,t=1.948,P＞0.05],but there was a significant difference in linear measurement between PA and direct measurement [(6.311±0.439) mm vs.(5.411±0.418) mm,t=9.956,P＜0.05].Conclusions CBCT can offer the diagnostic information for periodontal bone defect from three dimensional direction in the elderly,provide objective and accurate assessment of alveolar bone resorption,and has higher accuracy and reliability.

Objective: To introduce a new surgical procedure for the treatment of neck benign tumors by endoscopic techniques. Methods: Seventeen patients with neck benign tumor underwent surgery by endoscope through a concealed incision in Department of Oral and Maxillofacial Surgery, Qilu Hospital of Shandong University from January 2018 to August 2019 were analyzed, which included 3 cases of tumor in the submental area, 2 cases in submandibular region, 9 cases in lower pole region of parotid gland, 1 case in superior region of sternocleidomastoid muscle, 1 case in central region of sternocleidomastoid muscle, 1 case in inferior region of sternocleidomastoid muscle. All patients underwent routine preoperative examination and CT examination to evaluate tumor size, boundary, morphology and nature. According to the area where the tumor located, concealed incisions in different sites were designed. Lumps in the submental area and submandibular area were treated with oral vestibular sulcus incision. Benign tumors located in the lower pole region of parotid gland and the sternocleidomastoid muscle region were treated with approach of the short hidden postauricular incision. During the operation, the self-developed "maxillofacial suspension device" was used to provide the operating space. The tumors were completely removed with endoscope and all patients were followed up every 3 months. Results: All surgical procedures were performed as expected. Visual analogue scale (VAS) was 9.3 on average at 3 months after operation, all the patients were satisfied with the incision design and the cosmetic effect. No recurrences were found in patients with a follow-up period ranged from 1-15 months. Conclusions These studies have shown that endoscope-assisted neck benign tumor resection is a surgical procedure with covert incision and good cosmetic results.