title: Implant location and radiotherapy are the only factors linked to 2-year implant failure.
abstract: METHODS
  The subjects in this retrospective case series were derived from a review of 700 patient files within the implant practice of the Department of Periodontology, University Hospital, Catholic University of Leuven. Inclusion criteria were met by 412 patients (240 females, 172 males) receiving a total of 1514 Nobel Biocare dental implants. These patients were included based on data availability for the time period 2 years after abutment surgery (considered to represent late implant failure).
  
  
  METHODS
  Given the concern of the authors to assess the probability of late implant failure among clinic patients with certain local and systemic factors, the potential factors were multiple. The local factors included the following: implant length and diameter, bone quality and quantity, insertion site, type of edentulism, antibiotic use perioperatively, dehiscence and/or perforation of the site during surgery, and stability at insertion (measured by Periotest values). The related health and behavioral factors included the following: medications, smoking (<10 cigarettes/day, 10-20 cigarettes/day, >20 cigarettes/day), hypertension, ischemic cardiac problems, coagulation anomalies, gastric ulcers, thyroid disorders, hypercholesterolemia, rheumatoid arthritis, asthma, diabetes (types 1 and 2), Crohn's disease, and chemotherapy.
  
  
  METHODS
  The primary outcome was described as "late implant failure." The current study, which follows a similar study on early implant failure,(1) aims to identify negative influences on maintenance of integration. The authors used the clinical experience related to the 412 patients with 1514 implants to identify whether the observed failure rates were influenced by local and systemic factors. Failure was defined as "late" when occurring between abutment connection surgery and 2 years after this date. Patients/implants that were not available for this interval of time were not included. However, even when records were available, not all patient records provided all data sought.
  
  
  RESULTS
  Regarding local factors, the authors reported that implant diameter and location were relevant to late implant loss, whereas implant length was not (P value = .01, = .34, respectively; univariate generalized estimating equation [GEE] logistic regression). Regarding implant diameter, significantly more loss was noted for 5.00-mm implants when compared with the 4.00-mm or 4.75-mm implants. Failure related to location revealed that the maxilla compared with the mandible, posterior jaws compared with anterior jaws, and the posterior maxilla compared with all other oral locations were associated with more late failures (Table 1). Assessment of systemic factors revealed radiotherapy to be related to more late implant loss (P = .003). Neither systemic disease nor smoking exposure was associated with late failure.
  
  
  CONCLUSIONS
  The authors concluded that late implant failure was influenced by the local factor "implant location" and the systemic factor "radiotherapy." Neither smoking nor systemic health factors were found to adversely influence implant integration from abutment connection through 2 years' performance.
authors.affiliation: Mayo Clinic College of Medicine, Department of Dental Specialties, 200 First St., SW, Rochester, MN 55905, USA. Carr.Alan@mayo.edu
authors.forename: Alan B
authors.initials: AB
authors.lastname: Carr