Periodontics Division, Department of Dentistry, All India Institute of Medical Sciences, Bathinda, India.
Oral Health Sciences Centre, Post Graduate Institute of Medical Education & Research (PGIMER), Chandigarh, India.
Evid Based Dent. 2023 Sep;24(3):123-124. doi: 10.1038/s41432-023-00915-2. Epub 2023 Jul 11.
To summarize the data on association between periodontal diseases and cognitive impairment in adults this systematic review scrutinized various observational studies till September 2021. This review was carried out in accordance with the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA 2020) guidelines. The authors used PECO framework question,: population-Adults (18 years or older), exposure-adults suffering from periodontitis, comparator-adult group without periodontitis, outcome-adults at high risk for cognitive impairment.
CASE/CONTROL SELECTION: Search for the literature was conducted on PubMed, Web of Science, and Cumulative Index to Nursing and Allied Health Literature (CINAHL). Search was limited to human studies with no limitation to year of publication prior to September 2021. Search terms used were related to gingiva, oral bacteria like Porphyromonas gingivalis, gum inflammation, periodontitis, dementia, neuroinflammation, cognitive impairment, Alzheimer's disease, Parkinson disease. Following research, all the studies providing association between periodontal diseases and neurodegenerative diseases with quantitative measures were included in the study. Non-human studies, studies on patients below 18 year old, studies related to influence of treatment and in subjects already suffering from neurological disease were excluded. After removing duplicates, eligible studies were identified and data extracted by two reviewers to make ensure inter examiner reliability and to prevent data entry errors. Data from the studies were tabulated as study design, sample characteristics, diagnosis, exposure biomarkers/measures, outcomes and results.
Methodological quality of studies was assessed by adapted Newcastle-Ottawa scale. Selection of study groups, comparability and exposure/outcome were used as parameters. Case-control and cohort studies were considered as high-quality studies if six or more stars were awarded out of nine maximum stars and four or more stars for cross-sectional studies out of six stars. Comparability among the groups was studied by taking into account primary factors for Alzheimer's disease such as age and sex and secondary factors like hypertension, osteoarthritis, depression, diabetes mellitus, and cerebrovascular disease. For cohort studies, 10 year follow up and dropout of <10% was considered to be successful.
A total of 3693 studies were identified by two independent reviewers and finally 11 studies were included in the final analysis. Six cohort studies, three cross-sectional and two case-control studies were included after excluding remaining studies. Bias in studies was assessed by adapted Newcastle-Ottawa Scale. All included studies were of high methodological quality. Association between periodontitis and cognitive impairment was determined by using different criteria like International classification of disease, clinical measurement of periodontitis subjects, inflammatory biomarkers, microbes and antibodies. It was suggested that subjects with chronic periodontitis since 8 years or more, are at a higher risk of having dementia. Clinical measures of periodontal disease like probing depth, clinical attachment loss, alveolar bone loss were found to be positively associated with cognitive impairment. Inflammatory biomarkers and pre-existing elevated levels of serum IgG specific to periodontopathogens was reported to be associated with cognitive impairment. Within the limitations of the study, the authors concluded that though the patients with long-standing periodontitis are at greater risk for developing cognitive impairment by neurodegenerative diseases, the mechanism by which periodontitis can lead to cognitive impairment is still vague.
Evidence suggests a strong association between periodontitis and cognitive impairment. Still further studies should be done to explore the mechanism involved.
为了总结成年人牙周病与认知障碍之间关联的研究数据，本系统评价仔细审查了截至 2021 年 9 月的各种观察性研究。本评价按照系统评价和荟萃分析的首选报告项目（PRISMA 2020）指南进行。作者使用了 PECO 框架问题：人群-成年人（18 岁或以上）、暴露-患有牙周炎的成年人、对照组-无牙周炎的成年组、结局-认知障碍风险较高的成年人。
病例/对照选择：在 PubMed、Web of Science 和 Cumulative Index to Nursing and Allied Health Literature（CINAHL）上进行文献搜索。搜索范围仅限于人类研究，不限制 2021 年 9 月之前发表的文献的年份。使用的搜索术语与牙龈、口腔细菌（如牙龈卟啉单胞菌）、牙龈炎症、牙周炎、痴呆、神经炎症、认知障碍、阿尔茨海默病、帕金森病有关。在完成研究后，所有提供牙周病与神经退行性疾病之间定量关联的研究，包括具有定量措施的研究，都被纳入研究。排除非人类研究、18 岁以下患者的研究、与治疗影响相关的研究以及已经患有神经疾病的患者的研究。去除重复项后，确定了合格的研究，并由两名审查员提取数据，以确保内部检查人员的可靠性并防止数据输入错误。研究数据被列成表格，包括研究设计、样本特征、诊断、暴露标志物/测量、结局和结果。
使用改良的纽卡斯尔-渥太华量表评估研究的方法学质量。选择研究组、可比性和暴露/结局作为参数。如果病例对照和队列研究获得 9 个最大星中的 6 个或更多星，或横断面研究获得 6 个星中的 4 个或更多星，则被认为是高质量研究。通过考虑阿尔茨海默病的主要因素（如年龄和性别）和次要因素（如高血压、骨关节炎、抑郁、糖尿病和脑血管疾病）来研究组间的可比性。对于队列研究，10 年随访和失访率<10%被认为是成功的。
通过两位独立审查员共确定了 3693 项研究，最终有 11 项研究纳入了最终分析。在排除其余研究后，纳入了 6 项队列研究、3 项横断面研究和 2 项病例对照研究。使用改良的纽卡斯尔-渥太华量表评估了研究中的偏倚。所有纳入的研究都是高质量的。使用不同的标准，如国际疾病分类、牙周炎患者的临床测量、炎症生物标志物、微生物和抗体，来确定牙周炎与认知障碍之间的关联。研究表明，患有慢性牙周炎 8 年或以上的患者患痴呆的风险更高。牙周病的临床测量，如探诊深度、临床附着丧失、牙槽骨丧失，与认知障碍呈正相关。报告称，炎症生物标志物和牙周病病原体特异性的血清 IgG 水平升高与认知障碍有关。在研究的局限性范围内，作者得出结论，尽管长期患有牙周炎的患者患神经退行性疾病导致的认知障碍的风险更高，但牙周炎导致认知障碍的机制仍不清楚。
有证据表明牙周炎与认知障碍之间存在很强的关联。仍需要进一步的研究来探索所涉及的机制。
