Background: This aim of this study is to compare regenerative therapy of infrabony defects with and without administration of post-surgical systemic doxycycline (DOXY) 12 and 24 months after therapy.
Methods: In each of 57 patients, one infrabony defect (depth ≥ 4 mm) was treated regeneratively using enamel matrix derivative at two centers (Frankfurt am Main and Heidelberg). By random assignment, patients received either 200 mg DOXY per day or placebo (PLAC) for 7 days after surgery. Twelve and 24 months after surgery, clinical parameters (probing depths [PDs] and vertical clinical attachment level [CAL-V]) and standardized radiographs were obtained. Missing data were managed according to the last observation carried forward.
Results: Data of 57 patients (DOXY: 28; PLAC: 29) were analyzed (26 males and 31 females; mean age: 52 ± 10.2 years; 13 smokers). In both groups, significant (P <0.01) PD reduction (DOXY: 3.7 ± 2.2 mm; PLAC: 3.4 ± 1.7 mm), CAL-V gain (DOXY: 2.7 ± 1.9 mm; PLAC: 3.0 ± 1.9 mm), and bone fill (DOXY: 1.6 ± 2.7 mm; PLAC: 1.8 ± 3.0 mm) were observed 24 months after surgery. However, the differences between both groups failed to be statistically significant (PD: P = 0.574; CAL-V: P = 0.696; bone fill: P = 0.318).
Conclusions: Systemic DOXY, 200 mg/day for 7 days, after regenerative therapy of infrabony defects did not result in better PD reduction, CAL-V gain, or radiographic bone fill compared with PLAC 12 and 24 months after surgery, which may be attributable to low power and, thus, random chance.