Occurrence and clustering of complications in implant dentistry

Objectives The aim was to evaluate the overall occurrence and potential clustering of biological and technical complications in implant dentistry. Material and Methods 596 patients provided with implant-supported reconstructions were evaluated for the occurrence of (a) technical complications, (b) peri-implantitis and (c) implant loss during a period of 9 years. Time and type of event were scored, and potential risk factors were explored through parametric modelling of survival and hazards. Clustering of complications was assessed at the patient level, and patient satisfaction was evaluated by questionnaire completed at the 9-year examination. Results 42% of patients were affected by technical and/or biological complications during the 9-year observation period. Extent of therapy (Hazard Ratio 2.5: patients with partial jaw restorations; HR 3.9: patients with full jaw restorations) and a history of periodontitis (HR 1.6) were identified as risk factors. While technical complications occurred mostly as isolated events, 41% of subjects identified with peri-implantitis and 52% of subjects with implant loss also presented with other complications. The hazard for technical complications and implant loss peaked at 0.7 years and 0.2 years, respectively, while the hazard for peri-implantitis was consistent throughout the observation period. The overall proportion of satisfied patients at 9 years was high (95%), and only minor differences between individuals with and without complications were noted. Conclusions Complications following implant-supported restorative therapy were common findings. Extent of therapy and periodontitis were identified as risk factors. While technical complications occurred in an isolated pattern, peri-implantitis and implant loss demonstrated clustering with other types of complications.