Causal Effects of Social Vulnerability and Multimorbidity on Tooth Loss in Chile: A National Survey Analysis

Tooth loss reflects cumulative biological and social processes across the life course. However, population-level causal evidence on the influence of structural social vulnerability and multimorbidity on tooth-loss severity remains limited in middle-income contexts. This study evaluated the causal impacts of social vulnerability and multimorbidity on tooth-loss severity and retention in Chilean adults. We analyzed nationally representative data from the Chilean National Health Survey 2016–2017 (N=5,165 adults aged ≥20 years). Outcomes comprised ordinal severity (y1: functioning dentition, moderate loss, severe loss, edentulism) and continuous tooth count (y2). Exposures included a Social Vulnerability Index (SVI, 0–1) and Multimorbidity Score (MS, 0–1). We estimated confounder-adjusted proportional-odds and survey-weighted linear regression models. Population-averaged causal contrasts were obtained via g-computation comparing 75th and 25th exposure percentiles, with 95% confidence intervals from probability-proportional-to-size bootstrap (1,000 replications). Age-dependent edentulism trajectories were generated using discrete-time Markov projections. In the weighted population, 72.6% retained functional dentition whereas 5.5% were edentulous. Increasing SVI from 0.091 to 0.345 was associated with a 0.093-point severity increase and 1.52 fewer teeth. Increasing MS from 0.00 to 0.20 was associated with a 0.059-point severity increase and 1.23 fewer teeth. SVI showed larger population-averaged effects than multimorbidity. Structural social vulnerability and multimorbidity independently influence tooth-loss severity, with socioeconomic disadvantage showing stronger distributional effects across the life course.