The aims of the present study were to assess radiographically the effects of scaling/root planing combined with antibiotic therapy using tetracycline fibers (TCF): (I) on alveolar bone density and linear descriptors and (II) on supracrestal soft tissue density. 19 subjects with generalized adult periodontitis (with at least 20 teeth present, at least 4 teeth with pockets >4 mm and bleeding upon controlled force probing) and high cultural counts of Porphyromonas gingivalis were recruited from a pool of 57 patients. The full mouth treatment group (FT) consisted of 10 patients, who underwent a full mouth supra-gingival scaling and prophylaxis treatment and were instructed to rinse 2x daily with a 0.1% chlorhexidine solution. 1 week later, tetracycline-hydrochloride-containing fibers (Actisite periodontal fiber) were applied around all teeth. After 7-12 days, the fibers were removed and all teeth were scaled and root planed under local anaesthesia. The chlorhexidine rinsing continued for another 2 months. In 9 subjects (local treatment group LT), 2 teeth with periodontal lesions with pocket probing pepth (PPD) > or =5 mm were treated by placement of tetracycline fibers, which remained in place for 7 to 12 days. Upon removal of the fibers, scaling and root planing was performed on these 2 teeth, while the rest of the dentition remained untreated, and no chlorhexidine rinse was applied. 2 of the untreated teeth revealing similar periodontal lesions were chosen to represent sites affected by untreated periodontitis (NT). In this group, a limited local treatment was performed (2 teeth) with the inherent potential for recolonization from the untreated pocket sites. Standardized periapical radiographs were obtained from the 4 monitored sites within each patient at baseline (before treatment) and 2 and 6 months thereafter. One radiograph was exposed in a standard way for bone assessment. The second radiograph was underexposed, at about a 1/5 of the original exposure time to allow the evaluation of soft tissue. Mean changes in the linear parameters and changes in density (CADIA) observed at multiple sites within each patient and treatment group were used as the best estimate of treatment outcome. Over the observation period of 6 months, a significant difference in bone height changes was found between the untreated sites (median loss -0.29 mm) and the sites from full-mouth treated patients (median gain 0.24 mm, p=0.008). When comparing the baseline to the 6 months radiographs, a loss in bone density was observed for the untreated group (median=-2.13 CADIA). Both treatment groups revealed a gain in density (median=1.58 and 2.43 CADIA for the locally and the full-mouth treated groups, respectively). Differences in density were significant, both between the nontreated and locally treated sites (p=0.026) and between the nontreated sites and the sites from the full mouth treated patients (p=0.002). The analysis of the soft tissues showed a similar pattern of changes in density to those seen in the bone defect. At 2 months, there was a tendency for loss in density for the nontreated group (median=-0.17 CADIA) that continued over the 6 month period (median=-0.31 CADIA). A significant increase in density was observed for the full-mouth treated sites (median=1.57 and 0.64 CADIA for the 2 and 6 months radiographs, respectively). A significant increase was also observed for the locally treated group when compared to the untreated sites (median=0.13 and 0.10 CADIA for the 2 and 6 months radiographs, respectively). Comparing untreated sites with full-mouth treated sites, a significant difference was observed for CADIA measurements (p<0.001). No significant difference was observed comparing locally treated and untreated sites (p=0.24). It was concluded that scaling and root planing combined with TCF therapy can result in increased bone density and alveolar bone height. Full-mouth treatment seemed to result in more pronounced gains compared to local tre