Abstract
The acid etching effect of a new viscous 35% phosphoric acid dissolved in glycerol and known 35% gel phosphoric acid agent were investigated in vitro on 40 sound extracted premolars using concise orthodontic adhesive in bonding stainless orthodontic brackets. The results showed no significant difference in bond strength between the two etching agents at 0.05 significant level. But samples etched with Viscous phosphoric acid have higher numerical value. This finding was supported by the clinical investigation on 10 orthodontic patients in which the number of failure brackets was 8 for viscous phosphoric acid etching agent and 12 for gel phosphoric | acid agent after 11 months of treatment.
