Topical effect of a medically prescribed pediatric antibiotic on dental biofilm: a cross-over, in situ study.

objectiveThis study aimed to investigate the possible topical effect of a broad-spectrum antibiotic on dental biofilm formed in situ in the absence or presence of sucrose.

methodsA crossover study was conducted in three phases of 14 days each, during which 11 volunteers wore palatal devices containing 6 enamel blocks covered with meshes to allow biofilm formation. Dental blocks were extraorally submitted to a 20% sucrose solution at three different frequencies of exposure (0, 3 and 8 times/day), and to a suspension of amoxicillin/clavulanate potassium (A/CP) or a placebo (P) suspension at an 8-hour time interval application regimen. On the 14(th) day of each phase, biofilms were collected for microbiological (conventional culture) and molecular (Denaturing Gradient Gel Electrophoresis--DGGE) analyses.

resultsIn the absence of sucrose exposure (SE) and at the 3-time daily frequency, dental biofilms treated with A/CP showed lower total biofilm weight and lower counts of total microbiota than the ones treated with P (p>0.05). A/CP presented higher counts of Candida spp. when compared with P in the presence of SE, especially at the 8-time daily frequency (p<0.05). Considering the DGGE analysis, the mean number of bands was higher for P (p>0.05), regardless of SE. However, DGGE profiles demonstrated large interindividual variability.

conclusionBoth conventional culture and DGGE have demonstrated some differences on total microbiota of dental biofilms when exposed to the A/CP or P suspensions, mainly in the absence of sucrose, which suggests a possible topical effect of the sugar-free A/CP suspension on dental biofilm.