Caracterização físico-química de medicamentos de uso pediátrico: efeitos na microdureza e morfologia do esmalte dentário

Abstract

The objectives of this study were to establish the physicochemical characteristics of pediatric liquid oral medications and to evaluate in vitro their effects on the microhardness and morphology of permanent dental enamel, after different exposure times. In the first phase, 59 substances from 11 therapeutic classes (analgesics, antiinflammatory drugs, corticosteroids, antihistaminic drugs, antitussive drugs, bronchodilators, antibacterial drugs, anthelminthic drugs, antiemetic drugs, anticonvulsants and antipsychotics) were analyzed with respect to pH, total titratable acidity (TTA), total soluble solids content (TSSC) and total sugar content. In addition, information regarding the presence of sucrose, type of acid and type of sweetener content were collected from the printed directions for use supplied with each medicine. The second phase of the experiment was performed with the medications that presented pH<5.5, sucrose content, TTA>0.16% and TSSC>41.58%. Seventy dental fragments from third molars were obtained and 50 of them were embedded in acrylic resin. The buccal and lingual surfaces were polished and a 4x4 mm area was delimited for Knoop microhardness measurements (50 gf, 15 s, 5 indentations) before and after the immersion cycles in the medications. The specimens were randomly assigned to 5 groups (n=10), being 4 experimental groups (Claritin, Amplictil, Celestone and Vick Mel syrup) and one control group (distilled water). The immersion cycle was performed under agitation and consisted of a single exposure for 5 and 15 min. The other 20 dental fragments were assigned to groups for analysis by scanning electron microscopy (SEM) for a comparative appreciation of the results. Data were presented by descriptive statistics (means, standard deviation, median, minimum and maximum values). ANOVA, paired-t, Kruskal-Walis, Mann-Whitney and Wilcoxon tests were used with a 0.05 significance level and 95% confidence interval. The SPSS v. 18.0 software was used for construction of the databank and statistical analyzes. All the therapeutic classes presented acidic pH, with the antipsychotics presenting the lowest mean value (2.61). Most of the evaluated medications (56.0%) exhibited pH below 5.5, but there was a wide variation in the TTA (0.1 1.2%) and TSSC (10.4 57.1%) values. High total sugar content was measured in the antitussive drugs (53.3%). According to the printed directions for use supplied with the medications, more than half the formulations contained sucrose, 39.0% contained citric acid, and sodium saccharine and sorbitol were present in 36.4% and 34.8% of the formulations, respectively. Microhardness analysis showed no statistically significant differences (p>0.05) among the experimental groups, but statistically significant differences (p<0.05) were found within each group between the different exposure times. SEM micrographs showed different morphological alterations in enamel morphology. It may be concluded that most of the evaluated pediatric liquid oral medications presented chemical properties that indicate a potential demineralization effect on dental structure. Corrosive activity was observed for Claritin®, Amplictil®, Celestone® and Vick Mel syrup®, as there were changes in the Knoop microhardness values and alterations of the characteristics of the permanent tooth enamel surface.