Abstract / Summary
Background: Mastication is a fundamental oral function that supports food processing, preparation for swallowing and oral motor development. Beyond its mechanical role, chewing provides rhythmic sensory stimulation that can influence cortical activation, brain perfusion, hippocampal plasticity, and memory processes. However, the direct evidence in children linking chewing disorders to cognitive development is limited.Objective: This systematic review compiles pediatric mechanistic, human neurophysiological, and animal evidence regarding the relationship between chewing disorders or impairments and cognitive or neurobiological outcomes relevant to child development.Methods: This systematic review followed PRISMA 2020 guidance and was registered with PROSPERO (CRD420261400820). We searched PubMed, Scopus, Web of Science, and the Cochrane Library. Eligible studies included pediatric observational or intervention studies, human neuroimaging or neurophysiological studies, and animal experiments assessing chewing-related exposures and cognitive, neurobiological, neurophysiological, or oral functional outcomes. Data were synthesized narratively due to clinical and methodological heterogeneity. We assessed risk of bias using JBI tools, the SYRCLE risk-of-bias tool, and narrative physiological appraisal. Certainty of evidence was evaluated using GRADE principles.Results: Twenty studies were included: six pediatric studies, three human neurophysiological studies, and 11 animal studies. Pediatric evidence mainly linked mastication to oral function, eating behavior, masticatory efficiency, bite force, and texture processing. Human neurophysiological studies have demonstrated brain activation related to chewing and cerebral blood flow responses. Animal models consistently show that reduced mastication, soft or liquid diets, and tooth loss are associated with changes in hippocampal neurogenesis, BDNF/TrkB signaling, synaptophysin expression, neuron count, and memory and learning.Conclusion: Current evidence supports the biological plausibility of an oral-brain axis, but direct pediatric cognitive evidence remains insufficient. Based on the GRADE approach, the overall certainty of the evidence is low. Longitudinal pediatric studies and controlled interventions with standardized cognitive outcomes are needed.