Teledentistry triage by rural Kenyan dental hygienists and untreated caries: a target-trial emulation of referral delay under bandwidth constraints

Delayed referral of untreated caries from rural teledentistry triage is a structural feature of bandwidth-constrained store-and-forward systems, yet the size of the delay effect that such systems can reliably detect has not been characterised. No observational data were used: the analysis characterised the operating characteristics of the design under a declared variance structure with between-cluster standard deviation 6.0, residual standard deviation 4.5 and intraclass correlation 0.64. Power was estimated 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. Fifty-four clusters were required to detect a 5-percentage-point reduction in untreated caries at 80% power. The results quantify the trade-off between cluster count and minimum detectable effect, show that the estimator is approximately unbiased at the design values examined, and identify the cluster count below which plausible referral-delay effects cannot be separated from sampling variation. The contribution is a design benchmark for teledentistry triage evaluations in low-bandwidth settings, not a claim about the effectiveness of any deployed programme.