Mastoid Obliteration After Canal Wall Down Mastoidectomy Using Tissue Engineering Approaches with Polymers, Mesenchymal Stem Cells, and Bioactive Molecules: A Systematic Review

<b>Background</b>: Mastoid obliteration following canal wall down mastoidectomy reduces cavity-related morbidity. Conventional obliteration materials act primarily as passive fillers, whereas tissue engineering (TE) strategies aim to achieve biologically active bone regeneration. <b>Methods</b>: This systematic review was conducted in accordance with PRISMA 2020 guidelines. PubMed/MEDLINE, Embase, Scopus, and the Cochrane Library were searched from January 2010 to December 2025. Studies evaluating tissue engineering-assisted mastoid obliteration involving growth factors, mesenchymal stem cells, polymer scaffolds, or 3D-printed constructs were included. <b>Results</b>: Fifteen studies met inclusion criteria (12 preclinical and three clinical). Polymer-supported MSC constructs demonstrated the most consistent osteogenic enhancement in animal models. Clinical evidence remains limited to small PRP-based case series. <b>Conclusions</b>: Preliminary evidence suggests that tissue engineering-assisted mastoid obliteration has regenerative potential, although the evidence is limited by predominantly preclinical data and a moderate-to-high risk of bias. Standardized outcome measures and well-designed prospective clinical studies are required to confirm long-term safety and efficacy.