To investigate the expression patterns of E-cadherin and P-cadherin in murine-tooth germs at early developmental stages. Mandible samples of CD1 mice from embryonic day 12.5 to postnatal day 3.5 were collected. The expressions of E-cadherin and P-cadherin in murine mandibular first molar germs were detected by immunofluorescence and observed under confocal fluorescence microscope. HE staining was performed for tissue morphology. Both E-cadherin and P-cadherin were widely expressed in the epithelial tissues through early developmental stages. The E-cadherin expression was increased in polarizing pre-ameloblasts, whereas the P-cadherin expression declined. The expression of the P-cadherin could be detected in epithelial tissues before bud stage, and expressed in mature ameloblasts at secretory stage. The E-cadherin and P-cadherin expressed in different spatiotemporal expression patterns, indicating their individual functions during tooth development. P-cadherin might function in the secretion and mineralization of enamel.