关键词: 先天缺牙, 牙齿发育异常, 非综合征型, 基因突变

Abstract: Tooth agenesis is a hereditary developmental disorder of the dentition characterized by partial or complete absence of teeth，often accompanied by abnormalities in tooth morphology. Its pathogenesis is governed by complex interactions between multiple genetic determinants and environmental factors. Accumulating evidence has demonstrated that key genes，including muscle segment homeobox 1（MSX1），paired box gene 9（PAX9），axis inhibition protein 2（AXIN2），and ectodysplasin A（EDA），as well as major signaling pathways such as Wnt/β-catenin and TGF-β/BMP，play essential roles in tooth germ formation and in mediating epithelial-mesenchymal interactions during odontogenesis. Environmental factors，such as maternal malnutrition，drug exposure，and radiation，may act synergistically to induce developmental arrest of the tooth germ. Additionally，mutations in AXIN2 and related genes have also been linked to an increased susceptibility to colorectal cancer，suggesting that tooth agenesis may serve as a potential indicator for early tumor screening. This article systematically summarizes research advances in genetic and environmental pathogenic factors，providing a reference framework for individualized diagnosis and management of tooth agenesis.

Key words: tooth agenesis, dental developmental anomalies, non-syndromic, gene mutations