RESUMEN
The purpose of this research was to estimate the prevalence and intensity of bacteraemia associated with orthodontic treatment procedures. The four procedures investigated were: an upper alginate impression, separator placement, band placement, and adjustment of an archwire on a fixed appliance. Eighty-one children undergoing general anaesthesia (GA) for dento-alveolar surgery related to their orthodontic treatment were randomly allocated to the impression or separator group. A further 61 children, receiving treatment in the Outpatient Department, were included and randomly allocated to the banding or archwire adjustment groups. A cannula was inserted into either the left or right antecubital fossa using an aseptic technique. A baseline 6 ml sample of blood was taken before treatment and a second 6 ml sample was taken 30 seconds after the procedure. There was no significant difference in the number of positive blood cultures between baseline (nine, 23 per cent), and following an upper alginate impression (twelve, 31 per cent); between baseline (twelve, 27 per cent), and placement of a separator (fifteen, 36 per cent); between baseline (nine, 36 per cent), and fitting or placement of a band (eleven, 44 per cent); or between baseline (twelve, 33 per cent), and archwire adjustment (seven, 19.4 per cent). For the separator group only the mean total number of aerobic and anaerobic bacteria combined, isolated from the blood samples (cfu of bacteria per ml of blood), was significantly greater following the placement of a separator (2.2, SD 9.1), compared with baseline (0.9, SD 0.2; P < 0.02). This investigation demonstrates that the only orthodontic treatment procedure that causes a significant bacteraemia is the placement of a separator.