Clinical Diagnosis and Treatment of Gingival Metal Tattoo Using Optical Coherence Tomography and Er:YAG Laser-Assisted Microsurgery: A Case Series with an Ex Vivo Proof-of-Concept Study

Background: Gingival metal tattoos caused by prosthodontic treatment present esthetic problems. To date, their removal has been unpredictable because of invasive surgical methods and the lack of reliable diagnostic tools. Objective: This study investigated the potential utility of optical coherence tomography (OCT) for the non-invasive assessment of metal tattoos and evaluated the minimally invasive removal using Er:YAG laser microsurgery. Methods: This study comprised an exploratory ex vivo proof-of-concept experiment using three gingival metal tattoo models and a clinical case series of three patients with gingival metal tattoos. Ex vivo models were created using porcine gingiva with artificially embedded metal fragments, which were analyzed through OCT and histological examination. In the clinical cases, three women with anterior gingival metal tattoos underwent OCT followed by Er:YAG laser microsurgery under microscopic guidance between 2012 and 2013. Results: Ex vivo experiments showed highly reflective OCT signals corresponding to the histological locations of metal fragments within the connective tissue. Clinically, OCT enabled visualization and localization of findings consistent with metal fragments and provided guidance for Er:YAG laser removal. All three patients showed uneventful healing without postoperative pain. Follow-up was available for 1.5 months in Case 1 and for up to 13 years in Cases 2 and 3, with favorable long-term clinical and esthetic outcomes observed in the latter two cases. Conclusions: OCT may facilitate non-invasive assessment and localization of gingival metal tattoos. When combined with Er:YAG laser microsurgery, it may provide a feasible and minimally invasive approach with favorable esthetic outcomes.