目的: 评估中国农村重度牙周炎患者4年自然进展不同失牙数人群的基线特征，分析影响失牙数量的相关因素。方法: 纳入15~44岁的217名重度牙周炎患者，通过问卷调查、临床检查和影像学检查，分析其4年自然进展失牙情况，计算磨牙缺失数、有牙周膜增宽(widened periodontal ligament space, WPDL)的牙数、有根尖病变的牙数等牙周疾病和龋病相关的基线指标，比较不同失牙数人群的基线特征，并进一步分析影响不同失牙数的相关因素。结果: 在4年自然进展后，失牙共103颗，年人均失牙(0.12±0.38)颗。其中，无失牙组有174人，失牙1~2颗组有34人，失牙≥3颗组有9人。磨牙缺失最多，尖牙缺失最少。与新发失牙数显著呈正相关的基线指标包括骨吸收＞50%的牙数、骨吸收＞65%的牙数、探诊深度(probing depth, PD)≥5 mm的牙数百分数、PD≥7 mm的牙数百分数、临床附着丧失≥5 mm的牙数百分数、有骨下袋的牙数、有WPDL的牙数和有根尖周病变的牙数。多元有序Logistic回归分析结果显示，骨吸收＞50%的牙数(OR=1.550)、基线磨牙缺失数(OR=1.774)、有WPDL的牙数(1~2颗：OR=1.415；≥3颗：OR=13.105)、有根尖周病变的牙数(1~2颗：OR=4.393；≥3颗：OR=9.526)和龋/残根的牙数(OR=3.028)显著增加了新发失牙和多颗新发失牙的风险。结论: 在4年自然进展后，中国农村中青年的重度牙周炎患者失牙和多颗失牙风险与骨吸收＞50%的牙数、基线磨牙缺失数、有WPDL的牙数、有根尖周病变的牙数和龋/残根的牙数显著相关。

Objective: To evaluate the characteristics of severe periodontitis with various number of tooth loss during 4-year natural progression, and to analyze the factors related to higher rate of tooth loss. Methods: A total of 217 patients aged 15 to 44 years with severe periodontitis were included, who participated in a 4-year natural progression research. Data obtained from questionnaire survey, clinical examination and radiographic measurement. Tooth loss during 4-year natural progression was evaluated. The baseline periodontal disease related and caries related factors were calculated, including number of teeth with bone loss > 50%, number of missing molars, number of teeth with widened periodontal ligament space (WPDL), number of teeth with periapical lesions and etc. Characteristics of populations with various number of tooth loss and the related factors that affected higher rate of tooth loss were analyzed. Results: In 4 years of natural progression, 103 teeth were lost, and annual tooth loss per person was 0.12±0.38. Nine patients lost 3 or more teeth. Thirty-four patients lost 1 or 2 teeth, and 174 patients were absent of tooth loss. Molars were mostly frequent to lose, and canines presented a minimum loss. The number of teeth with WPDL, with periapical lesions, with intrabony defects, with probing depth (PD)≥7 mm, with PD≥5 mm, with clinical attachment loss≥5 mm, with bone loss > 50% and with bone loss > 65% were positively correlated to number of tooth loss. Results from orderly multivariate Logistic regression showd that the number of teeth with bone loss > 50% OR=1.550), baseline number of molars lost (OR=1.774), number of teeth with WPDL (1 to 2: OR=1.415; ≥3: OR=13.105), number of teeth with periapical lesions (1 to 2: OR=4.393; ≥3: OR=9.526) and number of teeth with caries/residual roots (OR=3.028) were significant risk factors related to higher likelihood of tooth loss and multiple tooth loss. Conclusion: In 4 years of natural progression, the number of teeth with bone loss > 50%, baseline number of missing molars, number of teeth with WPDL, baseline number of teeth with periapical lesions and number of teeth with caries/residual roots were significantly related to higher risk of tooth loss and multiple tooth loss among Chinese young and middle-aged patients with severe periodontitis in rural areas.