Supplementary Material for: Meta-analysis of global distribution of root-caries prevalence in middle-aged and elderly

Introduction: Root caries (RC) remains a global health problem leading to negative impacts on an elderly person’s well-being causing oral health–related quality of life issues, as inadequate nutrition and detrimental oral functionality. The present systematic review with meta-analysis is designed to synthesize existing research findings on the prevalence and experience of root caries globally over the past 30 years. It aims to describe its distribution by country and explore its links with various socioeconomic indicators. Methods: Selection criteria: Three electronic databases (PubMed, Embase and Scopus) were screened for observational epidemiological studies (cross-sectional and cohort studies) reporting the prevalence of RC and/or mean RC experience between 1990 and 2023. No language were applied. Study selection, data extraction and quality assessment were done in duplicate. . risk of bias was graded with customized quality assessment tools (Study Quality Assessment Tools NHLBI, NIH). Data collection and analysis: studies reporting on (1) root caries experience (mean and SD) and (2) on root caries prevalence (%), were used synthesize the results. It was assessed as decayed, missing, and filled teeth (RDMFT) Results: A total of 91 publications were included in the descriptive analysis; the estimated overall pooled mean RC was 2.87 teeth and the global estimated random-effects pooled RC prevalence was 41%. Low gross national income (GNI) countries reported a low mean number of RC (1.35 GNI<$5000), while high GNI countries reported a higher mean number of RC (3.45 GNI $10000- $19999). Countries of higher inequalities (Gini index) reported lower means medium RC (1.98 teeth) than countries with no inequalities (4.90 teeth). Conclusion: This study highlights the high caries burden among adult population globally by estimating overall trends and comparing against factors including area, GNI and Gini-index. The large magnitude of these inequities indicates that oral health equity can only be achieved taking into account socioeconomic factors on a global scale. The lack of uniform data collecting among studies as well as knowledge gap regarding the incidence and experience of RC in different countries.

引言：根面龋（root caries, RC）仍是全球性健康问题，会对老年人的健康福祉造成负面影响，引发与口腔健康相关的生活质量问题，同时伴随营养摄入不足及口腔功能受损。本项附带荟萃分析的系统综述旨在整合过去30年间全球范围内有关根面龋患病率与患病数的现有研究成果，描述其国家间分布特征，并探讨其与各类社会经济指标的关联。

方法
纳入标准：检索PubMed、Embase及Scopus三大电子数据库，筛选1990年至2023年间报告根面龋患病率和/或平均根面龋患病数的观察性流行病学研究（包括横断面研究与队列研究），未对研究语言设置限制。研究筛选、数据提取与质量评估均由两名研究者独立重复完成。偏倚风险采用定制化质量评估工具（美国国立心肺血液研究所（NHLBI）、美国国立卫生研究院（NIH）研究质量评估工具）进行分级。
数据收集与分析：纳入同时报告以下两项内容的研究：(1) 根面龋患病情况（均值与标准差）；(2) 根面龋患病率（百分比），以综合分析研究结果。根面龋患病情况以根面龋失补牙数（root decayed, missing, filled teeth, RDMFT）进行评估。

结果：总计纳入91篇文献用于描述性分析；估算得到的整体合并平均根面龋患病数为2.87颗牙，全球随机效应模型合并根面龋患病率估算值为41%。低国民总收入（Gross National Income, GNI）国家（GNI＜5000美元）报告的平均根面龋患病数较低（1.35颗），而国民总收入处于10000~19999美元区间的高国民总收入国家报告的平均根面龋患病数更高（3.45颗）。收入不平等程度较高的国家（基尼系数（Gini index）更高）报告的平均根面龋患病数（1.98颗）低于收入不平等程度较低的国家（4.90颗）。

结论：本研究通过估算整体流行趋势，并对比地域、国民总收入与基尼系数等相关因素，凸显了全球成人人群中沉重的根面龋疾病负担。此类健康不平等现象的严重程度表明，只有在全球层面考量社会经济因素，才能实现口腔健康公平。现有研究缺乏统一的数据收集标准，且不同国家在根面龋发病率与患病情况方面仍存在研究空白。