Abstract：
The literature is conflicting regarding salivary nitrite (NO2-)/nitrite and nitrate (NO2- and NO3-) levels in children affected by dental caries. For this reason, a systematic review to provide a consensus on the subject was propose, whose objective is to verify whether these molecules could be used as biomarkers in children with caries. A comprehensive search was performed on online database and eleven articles were included in the meta-analysis. The methodological quality of studies was assessed by Newcastle-Ottawa Scale recommended for case-control studies and by AXIS tool for cross-sectional studies. Grading of Recommendations Assessment, Development and Evaluation was used for the assessment of the certainty of the evidence for each outcome. The results showed lower NO2- levels in the group of children affected by dental caries (SMD = -2.18 [-3.24, -1.13], p < 0.01). Age, saliva collection and methods of evaluation can impact the results. When evaluating the severity of the condition, an important variation was detected in relation to the different evaluation methods NO2-/NO2- and NO3-. In conclusion, based on the evidence presented, the results suggest that NO2- levels in saliva are a possible biomarker of dental caries. Results should be evaluated with caution due to the very low evidence from primary studies. Longitudinal studies are necessary to strengthen this hypothesis.
摘要：
关于受龋齿影响的儿童的唾液亚硝酸盐（NO2-）/亚硝酸盐和硝酸盐（NO2-和NO3-）水平，文献相互矛盾。出于这个原因,建议进行系统审查，以就此主题达成共识，其目的是验证这些分子是否可以用作龋齿儿童的生物标志物。对在线数据库进行了全面搜索，并将11篇文章纳入荟萃分析。通过推荐用于病例对照研究的纽卡斯尔-渥太华量表和用于横断面研究的AXIS工具评估研究的方法学质量。建议评估的分级，开发和评估用于评估每个结果的证据的确定性。结果显示，受龋齿影响的儿童组中NO2-水平较低（SMD=-2.18[-3.24，-1.13]，p<0.01)。年龄,唾液收集和评估方法会影响结果。在评估病情的严重程度时，检测到与不同的评估方法NO2-/NO2-和NO3-有关的重要变化。总之,根据所提供的证据,结果提示唾液中NO2-水平可能是龋齿的生物标志物.由于初步研究的证据非常低，因此应谨慎评估结果。纵向研究是必要的，以加强这一假设。
