Autogenous tooth transplantation of canines: a prospective clinical study on the influence of extraoral storage time-guided adjunctive antibiotic therapy and patient-related risk factors affecting success, survival, and prognosis after two years of follow-up.

BACKGROUND: The aim of this study was to evaluate the influence of adjunctive antibiotic therapy and patient-related factors on the success, survival, and prognosis of autogenous canine transplants over a two-year period. METHODS: Sixty-seven patients (aged 11–37 years) underwent canine autotransplantation. According to extraoral storage time (EST: 0–3, 4–6, or 7–15 min), patients received either (1) no antibiotics, (2) a single intraoperative intravenous dose of doxycycline, or (3) the same dose followed by a five-day oral regimen. Because allocation of systemic adjunctive antibiotic therapy was EST-based, their effects could not be assessed independently. Clinical and radiographic evaluations were performed. Primary outcomes were survival and success. The secondary outcome was a composite prognostic estimate (percentage of criteria fulfilled). Associations were analysed using linear regression. RESULTS: After two years, the success rate was 90% (95% CI: 82–97%), survival was 100%, and the mean prognostic estimate was 86% (95% CI: 82–89%). The adjunctive antibiotic therapy regimen had no significant effect. Success decreased with smoking (β = -8.03; p = 0.025). The prognostic estimate declined with increasing age (β = -1.30 per year), closed apex (β = -11.84), ankylosis (β = -13.80), orthodontic extrusion (β = -12.04) and its duration (β = -0.49 per month), and smoking (β = -14.15) (all p < 0.05). CONCLUSIONS: Routine adjunctive antibiotic therapy did not improve outcomes when allocated according to EST, supporting antibiotic stewardship. Prognosis was mainly influenced by patient-specific factors, highlighting the importance of individualised risk assessment in canine autotransplantation. TRIAL REGISTRATION: DRKS00034011 (German Clinical Trials Register and WHO International Clinical Trials Registry Platform); registered retrospectively on 4 April 2024. https://trialsearch.who.int/Trial2.aspx?TrialID=DRKS00034011 .