Effect of zinc supplements on the incidence of caries and on the concentration of salivary A immunoglobulins in short stature school children

Abstract

Young children in Ecuador show high prevalence of chronic zinc deficiency, associated with a decline in cellular and humoral immunity, and increased risk of tooth decay. The research reported in this paper presents the effect of the daily consumption of 10 mg zinc sulfate versus the control group receiving a solution with an inactive substance during 42 weeks, on respectively the children’s weight, height, the immunoglobulin A (IgA) concentration in saliva, the plasma concentrations of zinc, and the indices of Klein and Palmer (DMFT and DMFS). In the survey special attention was given to the detection of early stage tooth decay, also called incipient decay. Parallel, information about the children’s hygiene and living condition was collected using structured questionnaires. Statistical analysis of the collected data revealed that DMFS is less and the final concentration of plasma zinc higher in the experimental group of children receiving daily a zinc supplement (17,30 ± 9,55 vs. 20,03 ± 10,74; p = 0,032; 123 ± 24,29 μg dl-1 vs. 105,57 ± 15,75 μg dl-1; p < 0,001). Multiple linear regression showed that zinc supplements are associated with reduced DMFS (beta = -3,9; p = 0,033) and DMFT (beta = -1,33; p = 0,05), and that the basal state of zinc allies with a lower final concentration of IgA in saliva (beta = - 0,043; p = 0,011). More intensive toothbrush with the use of toothpaste was associated with a reduction of DMFS (beta = -7,14; p = 0,033). Rinsing the mouth with potable water resulted in a decline of DMFT (beta = -1,42; p = 0,035). The study revealed that zinc supplements and oral hygiene positively affect oral health, likely through an improvement of oral mucosal immunity, which when applied will reduce the magnitude of this public health problem.