Dental Hygiene Students' Infection-Control Adherence Drift and Sharps Injury Incidence in Nigerian Teaching Hospitals: A Multilevel Variance Decomposition of Training-Cohort Saturation

Sharps injuries among dental hygiene students in Nigerian teaching hospitals are typically attributed to individual negligence or inadequate knowledge, yet adherence to infection-control protocols is a collective property of training cohorts whose size and supervision load vary across programmes. The framework is specified as a two-level model with random intercepts and random slopes, and the variance partition coefficient is derived to quantify the share of outcome variance attributable to cohort saturation. Because no primary data were collected, the paper reports the provenance of the DHS Program indicator on intimate partner violence (29 African countries, 82 country-survey observations, 2004–2025, mean 22.716, SD 8.912) as a methodological analogue for multilevel variance decomposition in low-resource African settings, and it uses the computed sample size (N = 82) and distributional statistics to illustrate the decomposition arithmetic. The contribution is a testable specification linking cohort saturation to adherence drift and injury incidence, with implications for clinical placement policy, supervision ratios and injury surveillance in dental hygiene training.