Objectives: The aim of this study was to assess the pulpal and periapical responses in dogs' teeth after direct pulp capping with a self-etching dentin adhesive. Methods: Standardized pulp exposures were performed in Class V cavities on the buccal surface of 40 premolars of 4 dogs, assigned to 3 groups: Group I (n=20) - Adper™ Prompt™; Group II (n=10) – zinc oxide-eugenol (positive control); Group III (n=10) – calcium hydroxide (negative control). The teeth were restored with resin composite (Filtek™ Supreme), and standardized periapical radiographs were taken (Ektaspeed Plus film) on the day of the treatment and after 7 and 70 days. The radiographs were processed in a dark room using the time/temperature method. After digitalization of the radiographic images, 3 calibrated examiners measured (in mm2), the radiolucent area suggestive of periapical lesion, where present, using the Image J 1.28 u software. Results: Data were submitted to statistical analysis and the following results were obtained (mean± standard error of the mean): Group I: 10.31(±1.45); Group II: 2.15(±0.43) and Group III: 0.00(±0.00). There was statistically significant difference between groups I and II (p<0.001) and groups I and III (p<0.001). Although no alteration suggestive of periapical lesion could be detected in Group III, there was no statistical difference between Groups II and III (p>0.05). Conclusion: According to the results obtained, the application of Adper™ Prompt™ self-etching dentin adhesive to the exposed pulp tissue yielded the development of radiographically detectable periapical lesions (Support: CAPES)