Teeth presenting external and internal resorption are uncommon, and affected teeth are often only discovered by chance. In most cases, these teeth are symptom-free. In rare cases, the differential diagnosis between external and internal resorption is very difficult, especially for teeth pretreated elsewhere with inadequate documentation of the clinical situation, as in the case presented. Resorption lacunae can also present a challenge for treatment. Invasive cervical resorption affecting the endodontium requires different therapeutic techniques in terms of position and timing. Presented is treatment of a case of pretreated, invasive cervical resorption with irreversible pulpitis. Root canal treatment was performed by filling the initial perforating resorption using MTA, and treatment of the cervical defect occurred later. Compared with incidents such as extrusion of H2O2 or NaOCl into the periradicular tissues during root canal irrigation, air inclusion in the tissue is comparatively less dramatic. However, this should be taken seriously. The present case report describes the treatment of a symptomatic invasive cervical resorption, with the occurrence of massive subcutaneous emphysema during the final cervical composite restoration. Keywords: emphysema, external resorption, invasive cervical resorption, mineral trioxide aggregate (MTA)