Role of Genetic Polymorphisms in Salivary Amylase and Their Impact on Carbohydrate Metabolism and Dental Caries Risks: A Systematic Review and Meta-Analysis

Background: Salivary amylase demonstrates an important role in carbohydrate metabolism and oral health and is influenced by the amylase alpha-1 gene (AMY1) gene polymorphisms. Amylase activity changes impact starch digestion, microbial interactions, and susceptibility to dental caries. This study aimed to investigate the impact of AMY1 copy number variations (CNV) on carbohydrate metabolism and susceptibility to dental caries. Methods: This systematic review and meta-analysis were conducted using the PRISMA 2020 guidelines. Up to May 2025, literature was retrieved in PubMed, Scopus, Web of Science, and Google Scholar. The eligible studies tested the relationship between AMY1 CNV or the salivary alpha-amylase and outcome in carbohydrate metabolism or dental caries. Information was independently obtained and then sifted. NOS and JBI were used in measuring the risk of bias. Meta-analyses were done based on odds ratios pooled according to a random-effects model; the outcomes of each single study are described narratively. I2 was taken as the measure of heterogeneity. Results: A total of nine studies were eligible, five of them being observational studies and four, cross-sectional, with the number of participants totaling 23,938. Two studies on meta-analysis exhibited a strong effect between AMY1 variation and elevated metabolic risk (OR = 1.20; 95% CI: 1.14, 1.26; I2 = 0%). Regarding dental results, there was no significant association between it and high heterogeneity (OR = 3.00, 95% CI: 0, 23 39.97 I2 = 87%). The risk of bias was low to moderate, and the GRADE certainty was moderate to low. Discussion: The relationship between AMY1 CNV and sAA activity shows promise for their development as individualized healthcare biomarkers between metabolic and oral health factors. However, the limited number of high-quality studies and variability in study designs may affect the generalizability of these findings. Additional research needs to be conducted to improve genetic screening procedures and clinical usage.