Overfilling of root canals is a common complication in endodontic therapy, with possible consequences such as infection, irritation, or nerve damage. Causes of overfilling include excessive cement application, inaccurate determination of working length, lack of apical constriction, over-instrumentation, and the use of injection techniques for filling. To minimize the consequences of overfilling, clinicians are advised to use biocompatible or bioactive materials, carefully measure the working length, and apply appropriate techniques for root canal preparation and filling. Complications may include pain, discomfort, damage to the inferior alveolar nerve leading to numbness and pain in the lower jaw, lips, cheeks, or face, and extrusion of material into the maxillary sinus, which can cause infection, tissue swelling, and chronic sinusitis. Outcomes of overfilling can range from complete resorption of the excessive material and healing of periapical tissue to permanent nerve damage or chronic inflammatory conditions. Treatment of overfilling may involve a „wait and see“ approach, endodontic revision, or surgical intervention, depending on the nature of the complications. In asymptomatic cases, patient monitoring may be sufficient, while surgical measures are necessary for more severe complications. Timely diagnosis and appropriate therapy are crucial for minimizing negative outcomes and ensuring the success of endodontic treatment. Clinicians must carefully evaluate each situation, and select the most suitable treatment for the patient.