Caries burden and oral hygiene behaviour among attendees at humanitarian dental clinics in Ukraine: a two-wave repeated cross-sectional study

Background. Recent on-the-ground oral health data from conflict-affected Ukraine are scarce. We characterised the oral health burden and behavioural determinants of caries severity across two humanitarian dental missions (April 2025 and April 2026) at two contrasting sites: geographically exposed Korosten and rear-area Ternopil. Methods. Civilians attending MacKay Memorial Hospital mobile clinics underwent a WHO-standardised examination by a single calibrated dentist and completed a Ukrainian-language behavioural questionnaire. The primary outcome was total DMFT; secondary outcomes included any untreated decay, high caries burden (DMFT ≥ 14), Care Index, and Unmet Need. A negative-binomial generalised linear model with robust standard errors and a four-knot restricted cubic spline for age, and logistic regression with stratified bias-corrected and accelerated (BCa) bootstrap (5,000 replicates) for binary outcomes, were fitted. Holm and Benjamini–Hochberg corrections were applied. Results. Of 112 civilians examined (2025 n = 46; 2026 n = 66; age 5–81 years; 52.7% male), 93.8% had caries experience; mean DMFT was 10.89 ± 7.40 with the missing component dominating (4.88 ± 5.78). The 2026 cohort was younger and reported twice-daily brushing more often (63.6% vs 43.5%). After adjustment, two predictors were stable across all sensitivity analyses: Korosten versus Ternopil (adjusted IRR 1.32, 95% CI 1.07–1.63, p = 0.009) and twice-daily brushing (IRR 0.73, 0.60–0.89, p = 0.002). Brushing held both Holm- (p = 0.014) and Benjamini–Hochberg- (p = 0.008) adjusted significance; Korosten held Benjamini–Hochberg correction (p = 0.028) but was attenuated under Holm (p = 0.065). Mission wave was not independently associated with DMFT or, after BCa bootstrap, with any untreated decay (adjusted OR 0.43, 0.16–1.19; p = 0.105). Adding ever-smoking did not alter the primary effects. Conclusions. Civilians attending humanitarian dental clinics in war-affected Ukraine carry a heavy caries burden dominated by missing teeth. A 32% higher caries burden in geographically exposed Korosten and a 27% reduction with twice-daily brushing both held under sensitivity analysis. Humanitarian dental responses should plan for higher per-patient need at exposed sites and embed brief, standardised oral hygiene support in every encounter.