Immediate early and delayed implants: A 2-year prospective cohort study of 131 transmucosal flapless implants placed in sites with different pre-extractive endodontic infections

Introduction: To evaluate clinical outcome of early, immediate, and delayed transmucosal implants placed in patients affected by acute/ chronic endodontic lesions. Materials and Methods: Eightyfive consecutive patients received 131 titanium implants with zirconiumoxide blasted surface. Pre-extractive diagnosis represented the main criteria for implant placement timing, following "best treatment" criteria. Implants were placed with flapless transmucosal technique. Hopeless teeth with chronic periapical lesions received atraumatic extraction, and an implant was immediately placed (Immediate Group, n = 29). Teeth with acute periapical lesion/abscess were extracted and implants placed after 8 to 12 weeks (Early Group, n = 29). Implants placed 10- to 12-month after extraction constituted the control group (delayed group, n = 73). Implants were loaded 3 months after insertion with provisional resin crowns and after approximately 15 days with definitive ceramic crowns. Marginal bone loss (MBL) was measured in a singleblind manner on periapical radiographs at 1, 3, 6, 12, and 24 months. Results: Multilevel analysis described exploring factors associated with MBL. Survival rate was 100%. MBL after 24 months was 0.78 6 0.70 (95% confidence interval [CI]: 0.20 to -1.37) at immediate, 0.48 6 0.70 at early (95% CI: -0.006 to -0.961), and 1.02 6 1.01 (95% CI: 0.61 to -1.43) at delayed groups. Implant groups (immediate/early/ delayed) and location (maxillary/ mandibular) showed statistically significant results. Early group showed the lowest MBL values. The immediate group demonstrated less MBL than the delayed group. Conclusion: Early implant placement technique preserves periimplant marginal bone level more than immediate and delayed techniques.