Point-of-Care Salivary Caries-Risk Testing in Community Dental Hygiene Therapy Clinics in Tanzania: A Stepped-Wedge Implementation Trial of Triage Accuracy and Therapy Allocation

Community dental hygiene therapy clinics in Tanzania allocate preventive and therapeutic resources under severe uncertainty about which patients will develop caries. Point-of-care salivary caries-risk testing promises to reduce that uncertainty, but its triage value depends on design properties that have not been characterised for the clinic-level rollout contemplated here. Power was estimated across 2000 design cells spanning 8, 16, 24 and 32 clusters and effects of 3, 5 and 8 percentage points. Fifty-four clusters were required to detect a 5-percentage-point effect at 80% power. The analysis characterises the operating characteristics of the design rather than reporting observational outcomes, and it identifies the cluster counts at which triage accuracy and therapy allocation can be distinguished from noise. The results imply that clinic-level rollouts below 24 clusters cannot reliably separate a clinically meaningful reallocation of therapy from secular change, and that the intraclass correlation of 0.64 dominates the design's sensitivity more than effect size does.