Objective:To explore the effect of 3D printing periodontal bone defect model of anterior teeth combined with case-based learning (CBL) teaching mode in the standardized residency training of loose teeth fixation.Methods:Sixty general practitioner of stomatology students were equally divided into two groups, with one group receiving CBL teaching (CBL group) and the other group receiving 3D printing model combined CBL teaching (3D+CBL group). After the teaching, the teacher evaluated the overall practice effects, tested the residents' theory and practice scores, and designed a questionnaire to evaluate the teaching effect. SPSS 16.0 software was used for statistical analysis, and t test was used for comparison between the two groups. Results:The theoretical score (89.0±3.2) and the practical score (90.0±2.5) in the 3D+CBL group were significantly higher than the theoretical score (83.3±3.6) and the practical score (84.2±3.5) in the CBL group ( P<0.05). The questionnaire showed that the students of the 3D+CBL group performed significantly better than those in CBL group in the following eight aspects, including mastery of basic periodontal knowledge, professional knowledge of loose teeth fixation, ability to diagnose cases and formulate treatment plans, clinical operation ability, interesting teaching content, willingness to communicate with teachers, awareness of actively receiving patients, and satisfaction of standardized residency training ( P<0.05). Conclusion:The 3D printing periodontal bone defect model of anterior teeth combined with the CBL teaching mode has achieved good results in the teaching of loose teeth fixation, and it provides a reference for the application of 3D printing in clinical teaching for periodontology.

【Objective】 To evaluate the efficacy of Nd: YAG laser therapy adjunct to subgingival scaling and root planning (SRP) for treating severe chronic periodontitis. 【Methods】 We selected patients with severe chronic periodontitis whose teeth were distributed in 4 quadrants of the mouth, with probing depth (PD) of 5-8 mm, attachment loss (AL)≥5 mm and bleeding on probing (BOP). These teeth were randomly divided into three groups: SRP group, SRP+L group (Nd: YAG laser after SRP treatment), and L+SRP group (SRP after Nd: YAG laser treatment). We recorded parameters including BOP, PD and AL of the three groups at baseline and 8 weeks after treatment and made statistical analysis. 【Results】 At 8 weeks after treatment, BOP, PD and AL of the three groups were improved than those in the baseline (P<0.05). BOP positive percentage of SRP+L group and L+SRP group significantly reduced compared with SRP group (P<0.05). PD of SRP+L group significantly decreased compared with SRP group and L+SRP group (P<0.05), for sites with PD=7 mm, SRP+L group was significantly decreased compared with SRP and L+SRP groups (P<0.05). AL of SRP group significantly decreased compared with SRP+L group and L+SRP group (P<0.05). 【Conclusion】 Severe periodontal treatment with Nd:YAG laser adjunct to SRP is more effective in reducing BOP and PD, and for deeper pockets PD is significantly decreased in SRP+L group, but there is no advantage in the improvement of AL.