Longitudinal changes in gingival condition in crowded and noncrowded dentitions subjected to fixed orthodontic treatment.

A previous study showed that initial crowding in the dentition was negatively correlated with gingival bleeding at the end of orthodontic treatment, whereas visible plaque on the labial surfaces had apparently no significant association with gingival health. The present study further examined the relationship between initial crowding and gingival health during fixed orthodontic treatment. A total of 220 patients were followed longitudinally during treatment. In this population, 2 groups, 1 consisting of 45 patients with severe crowding and 1 consisting of 52 patients with no crowding, were examined more closely. The gingival bleeding index (GBI) was recorded at bonding, at 12, 24, and 48 weeks after bonding, and at debonding. At bonding, the GBI was the same in the 2 groups. However, the GBI improved significantly from 12 weeks after bonding to debonding in the patients with crowded dentitions, whereas the patients with noncrowded dentitions showed no changes. Possible reasons for this difference were identified: to have the same GBI at bonding, despite the severe crowding, the patients in this group probably had better oral hygiene. Those with crowded dentitions had received more oral hygiene instruction within 2 years before bonding than those with noncrowded dentitions, according to the general practitioners' records. When the crowding was eliminated after approximately 3 months, the conditions for cleaning the teeth were improved, and, accordingly, the patients' improved oral hygiene resulted in lowered GBI scores. One could also speculate that correcting the crowding during the first few months of treatment had a positive psychological effect, motivating the patients to use the skills in oral hygiene that they had adopted before treatment.