初步探讨光动力联合龈下喷砂疗法治疗后种植体周围环境炎性因子以及微生物菌群分布的变化，为光动力疗法在种植体周围炎治疗中的应用提供理论依据。

本研究采取单中心、前瞻性、开放标签以及随机对照等研究方法，募集自2018年2月1日至2019年2月1日于首都医科大学附属北京朝阳医院口腔科就诊的伴种植体周围炎修复体共9例患者，16颗种植体，对种植体周围炎患者在接受光动力联合龈下喷砂疗法治疗前及治疗后1周、2周、4周、12周和24周提取龈沟液，并通过对龈沟液菌群分布的改变进行扩增子检测，通过生物信息学分析方法分析龈沟液菌群分布的改变，从致病菌群角度分析光动力疗法治疗种植体周围炎的可能机制（本试验分别在门、纲、目、科、属、种分类等级进行组间显著性差异分析。在Alpha多样性分析中差异分析使用R软件完成，检验方法使用秩和检验。

所有受试者均完成计划随访。接受光动力联合龈下喷砂治疗后的种植体周围炎患者治疗前后龈沟液样本的α多样性分析结果显示，种植体周围炎患者接受光动力联合龈下喷砂疗法治疗后5组Observed species、Chao及Ace指数均高于治疗前，其中Chao指数各组间差异有统计学意义（χ² = 5.688、P = 0.033），表明各组间OTU低丰度物种的改变有差异，操作分类单元分布呈现显著变化，多为低丰度菌群改变。β多样性分析结果显示，基于weighted_unifrac、unweighted_unifrac和bray_curtis距离的主坐标分析均显示各组间群落多样性差异无统计学意义，多元方差分析P均> 0.05。其中基于非加权Unifrac距离的主坐标分析提示治疗后24周与其他组区分更为明显，组间两两比较显示治疗后24周与其他5组β多样性差异均有统计学意义（P：χ² = 7.751、P = 0.005；W1：χ² = 6.471、P = 0.011；W2：χ² = 4.997、P = 0.025；W4：χ² = 3.612、P = 0.0415；W12：χ² = 3.125、P = 0.0486），提示在不考虑丰度信息下，治疗后24周群落的多样性与前组显著不同。

种植体周围炎患者接受光动力联合龈下喷砂疗法治疗前后多组间的龈沟液菌群组成未发生显著变化，治疗后24周的物种多样性显著高于治疗前，主要体现在非优势菌的增加。为进一步研究该疗法对种植体周围炎在调节局部微生态环境、长期维护过程中发挥的作用提供了理论基础。

To preliminatively investigate the changes of inflammatory factors and microbial flora distribution in the environment around implants following photodynamic therapy (PDT) combined with subgingival sandblasting therapy, and to provide theoretical basis for the application of PDT in the treatment of peri-implant inflammation.

A single-center prospective, open-label, randomized controlled study were adopted. Total of 9 patients and 16 implants were recruited from February 1st, 2018 to February 1st, 2019 in the Department of Stomatology of Beijing Chaoyang Hospital, Capital Medical University. Gingival crevicular fluid (GCF) was extracted from patients with peri-implantitis before combined therapy and after different treatment times, the changes of microflora in GCF were detected by amplifiers. Furthermore, changes of microflora distribution in GCF were revealed by bioinformatics analysis, in order to analyze the possible mechanism of PDT in the treatment of peri-implantitis from the point of view of pathogenic bacteria. In Alpha diversity analysis, R software was used for difference analysis, and rank-sum test was used for test.

All patients completed the planned follow-up. The α diversity analysis of GCF samples of patients before and after combined treatment showed that Observed species, Chao and Ace index of 5 groups of patients were all higher than before treatment, and Chao index showed significant difference among groups (χ² = 5.688, P = 0.033). β diversity analysis showed no significant difference in community diversity among groups (all P > 0.05). The principal coordinate analysis based on the unweighted Unifrac distance showed that the difference between the two groups was significant at 24 weeks after treatment. The pairwise comparison between the two groups confirmed that the β diversity was significantly different from that of the other five groups (P: χ² = 7.751, P = 0.005; W1: χ² = 6.471, P = 0.011; W2: χ² = 4.997, P = 0.025; W4: χ² = 3.612, P = 0.0415; W12: χ² = 3.125, P = 0.0486), indicating that colony diversity was significantly different from that of the former group at 24 weeks after treatment without considering abundance information.

There was no significant change in the composition of GCF in patients before and after combined therapy. The species diversity at 24 weeks after treatment was significantly higher than before, mainly reflected in the increase of non-dominant bacteria, which provides a theoretical basis for further study of the role of this therapy in the regulation of local microecological environment and long-term maintenance of peri-implantitis.