Background: A major drawback of traditional pulp testing procedures is that they depend on neural responses rather than vascular circulation. Hence, this study aimed to develop a custom-modified dental sensor using a finger pulse oximeter (PO) that is applicable to any type of tooth so as to test its ability and accuracy in evaluating the oxygen saturation (SaO₂) values of teeth at different developmental stages as a measure of pulp vitality. Materials and methods: A customized finger PO was employed to determine the systemic and pulp SaO₂ levels in 300 children. A total of 600 teeth (primary and permanent) were divided into group I (100 primary molars), group II (200 permanent molars), group III (200 permanent incisors), and 100 endodontically treated (primary and permanent) teeth were included in group IV. The mean SaO₂ values thus obtained in various groups were compared. Results: Intragroup comparison of mean SaO₂% of the patient's finger (systemic), test teeth, and control teeth showed significant differences (p ≤ 0.001). Intergroup comparisons also revealed significant differences in most of the groups. Conclusions: The modified PO probe can be applied to any type of tooth. It was found to be accurate and sensitive enough to detect changes in SaO₂ levels in various clinical situations irrespective of developmental stage. It proved to be a direct method of evaluation of pulp vitality by objective means.