Among radiological methods, magnetic resonance imaging (MRI) excels in its ability to image soft tissue at great contrast and without the need of harmful radiation. This study tested whether in vivo MRI based on standard MRI sequences run on a standard clinical MRI system can be used to quantify dental pulp response to caries progression using the T<sub>2</sub> mapping method. In the study, 74 teeth were scanned on a 3-T MRI system, and caries was assessed according to the International Caries Detection and Assessment System (ICDAS). The T<sub>2</sub> maps were processed to obtain T<sub>2</sub> profiles along selected root canals (from crown to apex), and the profiles were sorted according to both tooth type (single-rooted vs. molar) and ICDAS score. In all the examined dental pulps, it was found that T<sub>2</sub> values decrease with an increase in the ICDAS score. In the coronal part of dental pulps, average T<sub>2</sub> values of 166, 153, and 115 ms were found in ICDAS groups 0, 1–3, and 4–6, respectively. In single-rooted teeth, T<sub>2</sub> values were found approximately constant as a function of dental pulp depth, while in multi-rooted teeth, they were found increasing in the coronal part and decreasing towards the root apex. The study confirmed that T<sub>2</sub> mapping of dental pulp can be used to reliably quantify its response to caries progression and that it has a potential to become a complementary diagnostic tool to standard radiographic methods in the assessment of dental pulp response to caries.