Teledentistry triage by dental hygiene therapists and in-person periodontal treatment conversion in Botswanan rural clinics: a target-trial emulation of bandwidth constraints

Rural Botswanan clinics that rely on dental hygiene therapists to triage periodontal referrals through low-bandwidth teledentistry links face a design question that cannot be answered from observed conversion rates alone: how many clinics must be enrolled, and how large must the triage-to-treatment conversion effect be, before a before-after-control-impact evaluation can distinguish a real improvement from cluster-level noise? the present analysis reports a design and power analysis of that evaluation problem. No observational data are used or claimed. The analysis characterises the operating characteristics of the before-after-control-impact estimator under a declared variance structure with between-cluster SD = 6.0, residual SD = 4.5 and intraclass correlation = 0.64, across 2000 replications per design cell for cluster counts of 8, 16, 24 and 32 and effect sizes of 3, 5 and 8 percentage points. Power rose steeply with cluster count and effect size, and 54 clusters were required to detect a 5-percentage-point conversion effect at 80% power. The minimum detectable effect at 80% power fell as cluster count increased, and the residual-versus-fitted diagnostic showed no systematic pattern. The results imply that bandwidth-constrained teledentistry triage evaluations in Botswana should be planned around at least 54 clusters if a 5-percentage-point conversion gain is the target, and that smaller pilots cannot credibly separate therapist-mediated triage from clinic-level variation.