Paper detail

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

Clinical interpretation often assumes that observable performance provides sufficient information about the organization of an adaptive system. However, similar observable performance may correspond to distinct latent organizations. This study extends a previous multi-level framework by introducing a fourth analytical level centered on longitudinal viability. Using an exploratory single-case design in a Parkinsonian patient, gait data were recorded with instrumented insoles under three occlusal conditions: neutral natural occlusion (ONL), a 2.5-degree increase in vertical dimension of occlusion (OC2.5), and a 3-degree increase in vertical dimension of occlusion (OC3). Two measurement sessions were conducted eleven weeks apart, during which the participant underwent a structured sensorimotor intervention. The vertical dimension of occlusion was considered as an experimentally varied constraint applied to an adaptive neuromechanical system. Although observable performance remained globally comparable across conditions, PCA-based latent-space analysis revealed differentiated longitudinal centroid displacements. OC3 exhibited the smallest displacement, ONL an intermediate displacement, and OC2.5 the largest displacement. This hierarchy supports the relevance of a Level 4 framework centered on viability, understood here as an exploratory proxy for a configuration's capacity to maintain lower longitudinal reorganization over time. These findings remain within-subject, exploratory, and non-causal. They do not establish a validated clinical threshold, causal occlusal effect, or therapeutic optimum. More generally, the work suggests that clinical relevance cannot be inferred solely from instantaneous performance or static latent structure, but may also depend on the capacity of a configuration to sustain a coherent trajectory over time.