Background: Allergy to dental materials in prostheses and implants that leads to dental device dysfunction is a challenging problem. Objective: In this prospective study, we aimed to investigate the diagnostic role and impact of dental patch test (DPT) results on the outcome of proceeding dental procedures with the collaboration of our allergy clinic and dental clinics. Methods: A total of 382 adult patients with oral or systemic signs or symptoms due to the applied dental materials were included. A DPT with 31 items was administered. The clinical findings after dental restoration according to the test results were assessed in the patients. Results: The most common positivity detected in the DPT was due to metals, among which nickel (29.1%) was the leading cause. The frequency of self-reported allergic diseases and metal allergy was significantly higher in patients with at least one positive result in the DPT (p = 0.004 and p < 0.001, respectively). Clinical improvement after the removal of dental restoration was seen in 82% of the patients who had a positive DPT result, whereas this rate was 54% among paatients with negative DPT results (p < 0.001). The only factor that predicted improvement after restoration was the positivity in the DPT result (odds ratio 3.96 [95% confidence interval, 0.21-7.09]; p < 0.001). Conclusion: Our study showed that a self-reported metal allergy was an important finding to predict allergic reactions to dental devices. Therefore, patients should be questioned for the presence of metal allergy-related signs and symptoms before exposure to the dental materials to prevent possible allergic reactions. Furthermore, DPT results are valuable to guide dental procedures in real life.