A 5-Year Retrospective Assay of Implant Treatments and Complications in Private Practice: The Restorative Complications of Single and Short-Span Implant-Supported Fixed Prostheses.

PURPOSE: This report aims to describe the restorative outcome of 5,491 implant-supported single crowns, fixed partial dentures, and splinted restorations that were prescribed or had implants placed during the study period. Timing of the complications and the relationship between the complications and different factors (practitioner, patient, and restoration) are examined.

MATERIALS AND METHODS: Dental clinicians qualified in or before December 2004, registered in Victoria, and placing and/or restoring implants in private practice were invited to participate in the study. Data extraction was conducted by two trained and calibrated research assistants with specific training in implant terminology and previous research experience extracting data from dental records. Prostheses average time observed/in function was calculated using the difference between the definitive restoration date and the patient record examination date or the date of implant/restoration lost. Both descriptive statistics and generalized linear mixed modeling were used to describe the restorative complications.

RESULTS: Over the study period a total of 499 mechanical complications were recorded. Single-implant crowns had the largest sample size (n = 4,760) and a recorded complication rate of 2.56 per 100 prostheses per year. The majority of screw loosenings recorded in this study were inadequately described. In single-implant crowns, abutment screw loosening occurred at a rate of 0.07 per 100 per year while unspecified screw loosening occurred at a rate of 0.53. Lateral screw loosening was more common in lateral screw-retained implant crowns (1.06) than decementation was in cement-retained implant crowns (0.57). Esthetics (0.25), veneer chipping or fracture (0.41), and food packing/contact point issues (0.53) also represent significant portions of the restorative complications. Each type of complication presented with a slightly different timing profile. Clustering within the first year was common. The ratio of screw loosening between the group who prescribed between 1 and 100 during the study period and those who prescribed more than 501 implant restorations was 1:0.15 (P = .005). Patients with operator-reported attrition had double the rate of veneer fracture (P = .005). Contact point issues were approximately three times more common in the posterior segment (P = .001).

CONCLUSION: During the period of January 2005 to December 2009, screw loosening, lateral screw loosening, decementation, esthetic complication, veneer chipping or fracture, and food packing/contact point issues were recorded at different rates for different types of prostheses in the private practices included in this study. Clusters of several complications within the first year were observed. For single-implant crowns, screw-loosening complications were less frequent in the more experienced group. Operator-reported attrition was related to higher rate of veneering material fracture. More contact point complications were found in the posterior regions of the oral cavity.