The forgotten fat: A systematic review of mandibular adipose content

Bone marrow adipose tissue (BMAT) is increasingly recognized for its role in bone physiology and pathology, yet its characteristics in the mandible remain poorly understood compared to long bones and vertebrae. This systematic review aimed to summarize current knowledge on mandibular BMAT in healthy conditions. A systematic review was conducted in PubMed, PMC-PubMed, and the Cochrane Library up to March 2025, supplemented by manual searches. Studies were included if they assessed the distribution, quantity, or composition of BMAT in physiological mandibular bone from mammals. Data were synthesized narratively according to PRISMA 2020 guidelines. Out of 4356 records, 29 papers involving 3565 mandibles from 9 species were included. The weighted mean dried bone marrow fat fraction in healthy mandibles was 63 %, consistently lower than the 80 % weighted mean for healthy long bones in the included studies. Adipose volume per bone or marrow volume also suggested reduced fat content in the mandible. Fatty acid profiles indicated possible mandibular differences, with lower proportions of palmitic acid (16:0, 22-27 %) and higher stearic acid (18:0, 16 %) compared to long bones. A small study on caribou showed similar patterns, although interspecies variability was also evident. Mandibular BMAT is quantitatively lower and compositionally distinct from that of long bones, which may contribute to site-specific responses in bone metabolism. However, heterogeneity in methodologies and lack of data on mineralized tissue lipids underscore the need for standardized protocols and further investigation.