It has been claimed that different ion solutions containing sulfate induce crystal growth and might be a better alternative than conventional acid etching for enamel pretreatment in bracket bonding. It should thus combine optimal bond strength with easy and quick debonding. Two clinical experiments were performed to test this hypothesis. The first experiment dealt with the debonding procedure. Following conditioning with dilute sulfuric acid which contained sodium sulfate (to be termed solution A) on one side of the mouth and etching with 37% phosphoric acid on the other, brackets were bonded on the maxillary and mandibular incisors of twenty dental nurse students. Debracketing and a subsequent cleanup procedure were performed after 2 days. The mode of loosening was mainly between the enamel surface and adhesive on the crystal-growth-conditioned teeth and between the bracket mesh and adhesive on the teeth etched with phosphoric acid. This difference in mode of loosening was statistically significant (P less than 0.001). In the second experiment, which dealt with the clinical bond strength, 250 brackets were bonded in forty patients. One side served as a control and was conventionally acid etched. On the experimental side conditioning was done with solution A in thirty patients. In ten patients, 10% phosphoric acid was added to the dilute sulfuric acid used (to be termed solution B). Failure rates and modes of failure were recorded for a 6-month period.(ABSTRACT TRUNCATED AT 250 WORDS)