Influence of Exposure Time on Erosive Effect of Liquid Medicines

Objective: To evaluate, in vitro, the influence of exposure time on erosive effect of two pediatric liquid medicines. Methods: Fifty-two bovine enamel blocks were mounted in acrylic devices and covered with red nail varnish to expose a window of polished enamel (1 mm in diameter). An antihistamine (Histamin®), an antibiotic (Neo Moxilin®), and negative (distilled water) and positive (0.6% citric acid) controls were tested. After pH and titratable acidity (ml of 0.1 N NaOH) analysis of each medicine and controls, the 52 enamel blocks were randomly divided into four treatment groups: GI (n=13) – Antihistamine (pH=5.1; 1.7 ml ), GII (n=13) – antibiotic (pH=5.3; 1.1 ml ), GIII (n=13) – 0.6% citric acid (pH=2.0; 20 ml ), and GIV (n=13) – distilled water (pH=5.6; 0.1 ml ). Samples were immersed in the solutions for 5, 15, and 30 minutes. Enamel roughness was determined in the baseline and after each treatment period with a Surftest (Mitutoyo SJ-201). A mean roughness value of three different sites was obtained for each sample according to treatment and exposure time. The enamel blocks were also prepared for SEM analysis. Two-way ANOVA for repeated measures was used for statistical analysis at a significance level of 5%. Results: Only GIII showed roughness values statistically different from the other groups (p<0.001), and also only in this group those values increased within time (p>0.05). However, the qualitative analysis of SEM images showed progressive erosion patterns for all groups, except for GIV and for enamel blocks from baseline. On photomicrographies, severity of erosion increased with exposure time and showed the following pattern: GIII > GI > GII. Conclusions: SEM demonstrated the tested pediatric liquid medicines eroded bovine enamel, and the erosion pattern was influenced by exposure time. However, none of them came to significantly influence enamel roughness. Supported by FAPERJ/CNPq.