From Organization to Viability: A Multi-Level Analysis of Gait Dynamics Under Occlusal Constraint

Clinical interpretation often assumes that observable performance sufficiently reflects the organization of an adaptive system. The preceding Level 3 study showed that neither an aggregated scalar score nor a static exploratory UMAP embedding uniquely resolved the occlusal observational probes. This study introduces Level 4, centered on observed longitudinal viability. Using an exploratory single-case design in a participant with Parkinson's disease, gait was recorded with instrumented insoles under three probes: neutral natural occlusion (ONL), a nominal 2.5-degree increase in vertical dimension of occlusion (OC2.5), and a nominal 3-degree increase (OC3). Two sessions were conducted eleven weeks apart. A common PCA representation was used to compare M1-M2 centroid displacement. In the selected PC1-PC2 plane, OC3 showed the smallest Euclidean displacement, ONL an intermediate displacement, and OC2.5 the largest. This ordering was preserved in most bootstrap iterations but was not preserved after Mahalanobis covariance normalization, showing that within-condition dispersion contributes to the result. Level 4 therefore provides a retrospective, representation-dependent proxy for longitudinal reorganization when static representations remain non-identifying. The findings are exploratory and non-causal. They do not establish distinct physiological states, a causal occlusal effect, a validated viability threshold, a therapeutic optimum, or a covariance-independent ranking.