Purpose: The aim of this study was to determine the prevalence of interproximal open contacts between singleimplant prostheses and adjacent teeth, as well as to provide guidelines to prevent interproximal contact loss (ICL). Materials and Methods: This was a retrospective, cross-sectional study. One hundred twenty-eight patients (174 single-implant restorations) from Columbia University College of Dental Medicine and a private faculty clinic with a single-implant restoration in the posterior or anterior region were selected to participate in this study. Patients between the ages of 19 and 91, both male and female, were included in this pilot study. The period of evaluation after implant restoration insertion was between 3 months and 11 years. Participants were seen at random intervals to identify ICL. Interproximal contacts were evaluated with 0.07-mm-thickness dental floss and visual confirmation. Contact was considered open if floss passed without resistance from adjacent teeth. Results: The results of this study revealed a significant percentage of ICL, 52.8%, between single-implant restorations and adjacent teeth; 78.2% were identified on the mesial surfaces and 21.8% on the distal surfaces. ICL was noted in 57.9% of the maxillary implant restorations and 49% of the mandibular implant restorations. Eight implant restorations in women demonstrated mesial and distal openings. Among the patients with ICL, a significant percentage, 40%, were aware of the presence of ICL and food impaction. Conclusion: In this study, 52.8% of implant restorations demonstrated ICL. This result dictates that ICL should be included as a prosthetic implant complication. The high prevalence of ICL is justification for proper informed consent, and associated clinical problems need to be addressed. Possible causative factors were presented, but further research is necessary to identify the causative factors for ICL. The authors suggest the use of an Essix retainer to prevent ICL between single-implant restorations and adjacent teeth. Evaluation of interproximal contact between implant restorations and the adjacent teeth should be periodically monitored. Schlagwörter: implant complications, implant prosthesis, interproximal open contacts