Caries prevalence on the buccal surfaces of teeth in orthodontic patients was determined with QLF and visual examination immediately after removal of fixed appliances. The number of lesions found by QLF far out-numbered that found by visual examination, but the distribution pattern was similar. 97% of all subjects and on average 30% of the buccal surfaces in a person were affected. On average, in males 40% of surfaces and in females 22% showed white spots (p < 0.01). Caries prevalence was lower (p < 0.01) in incisors and cuspids than in molars and premolars. A positive correlation with caries prevalence was found for the bleeding scores 6 weeks after debonding and lactobacillus counts before debonding. Mutans streptococci counts, age, treatment duration, socioeconomic status and dietary habits showed no correlation with caries prevalence.